Download Dynamic Equilibria in Solvent-Mediated Anion, Cation and Ligand

FULL PAPER
DOI: 10.1002/chem.200900796
Dynamic Equilibria in Solvent-Mediated Anion, Cation and Ligand
Exchange in Transition-Metal Coordination Polymers: Solid-State Transfer or
Recrystallisation?
Xianjin Cui,[a] Andrei N. Khlobystov,*[a] Xinyong Chen,[b] Dan H. Marsh,[a]
Alexander J. Blake,[a] William Lewis,[a] Neil R. Champness,[a] Clive J. Roberts,[b] and
Martin Schrçder*[a]
Abstract: The solution properties of a
series of transition-metal–ligand coordination polymers [ML(X)n]1 [M =
AgI, ZnII, HgII and CdII ; L = 4,4’-bipyridine (4,4’-bipy), pyrazine (pyz), 3,4’-bipyridine (3,4’-bipy), 4-(10-(pyridin-4yl)anthracen-9-yl)pyridine (anbp); X =
NO3, CH3COO, CF3SO3, Cl, BF4 ;
n = 1 or 2] in the presence of competing anions, metal cations and ligands
have been investigated systematically.
Providing that the solubility of the
starting complex is sufficiently high, all
the components of the coordination
polymer, namely the anion, the cation
and the ligand, can be exchanged on
contact with a solution phase of a competing component. The solubility of coordination polymers is a key factor in
the analysis of their reactivity and this
solubility depends strongly on the
physical properties of the solvent and
on its ability to bind metal cations constituting the backbone of the coordination polymer. The degree of reversibility of these solvent-induced anion-exchange transformations is determined
by the ratio of the solubility product
constants for the starting and resultant
complexes, which in turn depend upon
the choice of solvent and the temperature. The extent of anion exchange is
Keywords: cadmium · ion exchange · mercury · metal–organic
frameworks · silver · supramolecular chemistry · zinc
[a] X. Cui, Dr. A. N. Khlobystov, Dr. D. H. Marsh, Prof. Dr. A. J. Blake,
Dr. W. Lewis, Prof. Dr. N. R. Champness, Prof. Dr. M. Schrçder
School of Chemistry
University of Nottingham, University Park
Nottingham, NG7 2RD (UK)
Fax: (+ 44) 115 951 3563
E-mail: [email protected]
[email protected]
[b] Prof. Dr. X. Chen, Prof. Dr. C. J. Roberts
School of Pharmacy
University of Nottingham, University Park
Nottingham, NG7 2RD (UK)
Supporting information for this article is available and contains
single-crystal X-ray structural data, views of structures and packing
diagrams for 1–7 and hydrogen-bonding tables. IR spectroscopic and
powder X-ray diffraction data for coordination polymers and their exchange products, mass spectrometric and NMR spectroscopic data is
also available on the WWW under http://dx.doi.org/10.1002/
chem.200900796.
Chem. Eur. J. 2009, 00, 0 – 0
controlled effectively by the ratio of
the concentrations of incoming ions to
outgoing ions in the liquid phase and
the solvation of various constituent
components comprising the coordination polymer. These observations can
be rationalised in terms of a dynamic
equilibrium of ion exchange reactions
coupled with Ostwald ripening of
crystalline products. The single-crystal
X-ray structures of [AgACHTUNGRE(pyz)ClO4]1
(1), {[Ag(4,4’-bipy)ACHTUNGRE(CF3SO3)]·CH3CN}1
(2),
{[Ag(4,4’-bipy)ACHTUNGRE(CH3CN)]ClO4·
0.5 CH3CN}1 (3), metal-free anbp (4),
[AgACHTUNGRE(anbp)NO3ACHTUNGRE(H2O)]1 (5), {[Cd(4,4’bipy)2ACHTUNGRE(H2O)2]ACHTUNGRE(NO3)2·4 H2O}1 (6) and
{[Zn(4,4’-bipy)SO4ACHTUNGRE(H2O)3] ·2 H2O}1 (7)
are reported.
Introduction
Metal–ligand coordination polymers are complex compounds comprising three main components: i) metal cations,
ii) organic ligands linking metal cations and iii) associated
anions that afford charge balance. These materials have attracted a great deal of attention[1–6] not only because of their
ability to form unusual structures[7] , but also due to their potential applications in physical and chemical adsorption,[8–16]
ion exchange,[17–19] heterogeneous catalysis,[20–21] electronic
and optical properties,[22] separation processes,[23–25] sensor
technology,[26] and drug delivery.[27] Ion exchange, one of the
most interesting properties of metal coordination polymers,
has been extensively investigated,[17–19, 28–35] and solvent-mediated ion-exchange reactions have been commonly assigned
as “solid-state processes” even though often no unequivocal
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&1&
These are not the final page numbers! ÞÞ
evidence is given for such a mechanism or assignment. Compared to typical molecular complexes of low to medium molecular weights, many coordination polymers have a perceived low solubility in most conventional solvents and so
are often described as “insoluble”.[17, 18, 29] In addition, it has
been shown that crystals of the coordination polymer may
retain their morphology, shape and size (the “crystal envelope”), but lose their crystallinity on ion exchange.[35, 36]
Moreover, some single-crystal to single-crystal exchange
processes have been reported.[25, 37, 38] Based upon these observations, a general view has formed that ion exchange processes in coordination polymers take place through a solidstate diffusion mechanism.[25, 29–36, 39] Such a solid-state mechanism implies that ion exchange proceeds through the diffusion of free ions within channels of coordination polymer
crystals or microcrystals.[40, 41] Recently, we have demonstrated[42, 43] that ion exchange in AgI polymers with heterocyclic
ligands occurs through a solvent-mediated mechanism[44]
and not through a solid-state process. This solvent-mediated
process involves dissolution of the initial coordination polymer, followed by the formation and crystallization of a new
coordination polymer from the solution phase.
We report herein extended and systematic studies of the
solution properties of a range of coordination polymers,
demonstrating that cation and ligand exchange, as well as
anion exchange, can take place in these materials through a
solvent-mediated process. By studying the exchange processes for different anions, metal cations and ligands in different
solvents and at different temperatures, we have established
some general rules for the reactivity of coordination polymers which are essential for the understanding of their
chemical properties and function. NMR spectroscopy has
been used to quantify the soluble components of the polymers and elemental analytical data, FT-IR spectroscopy,
mass spectrometry, X-ray powder diffraction (PXRD),
atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been employed to monitor a series of
solvent-mediated exchange processes.
Experimental Section
All chemicals were purchased from Sigma–Aldrich. Elemental analyses
were carried out at the University of Nottingham analytical services and
infrared spectra were collected as KBr pellets by using a Bruker Tensor
27 FT-IR spectrometer. NMR spectra were recorded by using a Bruker
DPX 300 spectrometer at 300 MHz and mass spectra recorded by using a
Bruker MicroTOF mass spectrometer. X-ray powder diffraction patterns
were obtained by using a Philips X’pert powder diffractometer using a
CuKa source. AFM observation was completed by using a multimode
AFM (Veeco Instruments Ltd), using NP-S probes of spring constant
0.1 N m1. Measurements of the solubility of coordination polymers were
based on the concentration of ligand (4,4’-bipyridine or pyrazine) in saturated solutions of the corresponding complexes as determined by
1
H NMR spectroscopy. To quantify the concentration of ligand in the saturated solution of coordination polymer, a known amount of 1,3,5-tribromobenzene was added to the saturated solutions as a standard. The
concentration of ligand was then calculated by comparing the integral intensity of the corresponding NMR peaks of the ligand with the integral
&2&
www.chemeurj.org
intensity of the peak of 1,3,5-tribromobenzene ([D4]methanol, 7.76 ppm,
s, 3 H).
Synthesis of ligands 3,4’-bipyridine and 4-(10-(pyridin-4-yl)anthracen-9yl)pyridine: The ligands 3,4’-bipy and anbp were synthesised by Suzuki
coupling of 3-bromopyridine for 3,4’-bipy and 9,10-dibromoanthracene
for anbp, with 2-(4-pyridyl)-4,4,5,5-tetramethy-1,3-dioxabrolane, which
can be prepared from 4-aminopyridine.[45, 46]
3,4’-Bipyridine: brown viscous liquid, 1H NMR (300 MHz, CDCl3, 258C):
d = 8.91 (1 H, s); 8.75 (3 H, m); 7.95 (1 H, d); 7.55 (2 H, d); 7.45 ppm (1 H,
s).
4-(10-(Pyridin-4-yl)anthracen-9-yl)pyridine: yellow solid, 1H NMR
(300 MHz, [D4]methanol, 258C): d = 8.85 (4 H, m); 7.6 (8 H, m); 7.42 ppm
(4 H, m); elemental analysis calcd (%) for C24H16N2 : C 86.72, H 4.85, N
8.43; found C 86.61, H 4.89, N 8.42.
Synthesis of [Ag(L)NO3]1 (L=3,4’-bipy, anbp): The complexes were prepared by analogous routes. A solution of 3,4’-bipyridine (400 mg,
5 mmol) in CH3OH (10 mL) was added dropwise to a solution of AgNO3
(0.85 mg, 5 mmol) in CH3OH (20 mL) without stirring. After standing at
room temperature for up to 1 week, the mixture was filtered and the
brown powder collected. The product was washed three times with
EtOH (100 mL) and water (20 mL), dried in vacuo and characterised by
PXRD, IR and elemental analysis. Elemental analysis calcd (%) for
[Ag(3,4’-bipy)NO3·H2O]1, C10H10N3AgO4 : C 34.91, H 2.93, N 12.21;
found: C 34.96, H 2.60, N 11.96; elemental analysis calcd (%) for [AgACHTUNGRE(anbp)NO3·2.5 H2O]1, C24H21N3AgO5.5 : C 52.65, H 3.87, N 7.68; found: C
52.60, H 3.43, N 7.08.
Synthesis of [Ag(4,4’-bipy)X]1 (X=NO3, CF3SO3, BF4 or ClO4) and
[M(4,4’-bipy)ACHTUNGRE(NO3)2]1 [M=ZnII, CdII, HgII]: Typically a solution of metal
salt (5 mmol) in CH3CN (10 mL) was added dropwise to a solution of
4,4’-bipyridine (780 mg, 5 mmol) in CH3CN (20 mL) without stirring at
room temperature. After standing at room temperature for up to 1 week,
the mixture was filtered to obtain white powder. The powder was washed
three times with CH3CN (100 mL), dried in vacuo and characterised by
PXRD, IR spectroscopy and elemental analysis. Elemental analysis calcd
(%) for [Ag(4,4’-bipy)NO3]1, C10H8N3AgO3 : C 36.84, H 2.47, N 12.89;
found: C 36.84, H 2.39, N 12.93; elemental analysis calcd (%) for
[Ag(4,4’-bipy)BF4]1, C10H8N2AgBF4 : C 34.23, H 2.3, N 7.98; found: C
34.15, H 2.19, N 7.76; elemental analysis calcd (%) for [Ag(4,4’-bipy)ClO4]1, C10H8N2AgClO4 : C 33.04, H 2.22, N 7.71; found: C 32.98, H 2.08,
N 7.55; elemental analysis calcd (%) for [Ag(4,4’-bipy)CF3SO3]1,
C11H8N2AgF3SO3 : C 31.98, H 1.95, N 6.78; found: C 30.77, H 1.85, N
6.94; elemental analysis calcd (%) for [Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1,
C10H8N4ZnO6 : C 34.74, H 2.33, N 16.21; found: C 34.62, H 2.24, N 15.90;
elemental analysis calcd (%) for [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1, C10H8N4CdO6 :
C 30.58, H 2.05, N 14.27; found: C 30.54, H 1.98, N 13.89; elemental analysis calcd (%) for [Hg(4,4’-bipy)ACHTUNGRE(NO3)2]1, C10H8N4HgO6 : C 24.97, H
1.68, N 11.65; found: C 23.41, H 1.50, N 11.40.
Synthesis of [Zn(4,4’-bipy)X2]1 (X=Cl, NO3, CH3COO, BF4 or
SO42): Typically, a solution of 4,4’-bipyridine (780 mg, 5 mmol) in
MeOH (10 mL) was added dropwise to a solution of ZnII salt (5 mmol)
in MeOH (20 mL) without stirring. After standing at room temperature
for up to 1 week, the mixture was filtered to obtain white powder. The
powder was washed three times with MeOH (100 mL) and water
(20 mL), dried in vacuo and characterised by PXRD, IR spectroscopy
and elemental analysis. Elemental analysis calcd (%) for [Zn(4,4’bipy)Cl2]1, C10H8N2ZnCl2 : C 41.27, H 2.76, N 9.58; found: C 40.98, H
2.65, N 9.32; elemental analysis calcd (%) for [Zn(4,4’-bipy)ACHTUNGRE(CH3COO)2]1, C14H14N2ZnO4 : C 49.48, H 4.16, N 8.25: found: C 49.23,
H 4.08, N 8.11; elemental analysis calcd (%) for [Zn(4,4’-bipy)1.5ACHTUNGRE(BF4)2ACHTUNGRE(H2O)2]1, C15H16N3ZnB2F8O2 : C 35.33, H 3.16, N 8.24; found: C 35.21, H
3.12, N 7.77; elemental analysis calcd (%) for [Zn(4,4’-bipy)ACHTUNGRE(SO4)·6 H2O]1, C10H20N2ZnSO10 : C 28.20, H 4.74, N 6.58; found: C 28.10,
H 3.19, N 6.21.
Synthesis of [AgACHTUNGRE(pyz)X]1 (X=NO3, CF3SO3, BF4 or ClO4): Typically,
a solution of pyrazine (400 mg, 5 mmol) in EtOH (10 mL) was added
dropwise to a solution of AgI salt (5 mmol) in EtOH (20 mL) without
stirring. After standing at room temperature for up to 1 week, the mixture was filtered to obtain a white powder which was washed three times
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
with EtOH (100 mL) and water (20 mL), dried in vacuo and characterised by PXRD, IR and elemental analysis. Elemental analysis calcd (%)
for [AgACHTUNGRE(pyz)NO3]1, C4H4N3AgO3 : C 19.21, H 1.61, N 16.81, found: C
19.01, H 1.49, N 17.01; elemental analysis calcd (%) for [AgACHTUNGRE(pyz)BF4]1,
C4H4N2AgBF4 : C 17.49, H 1.47, N 10.20; found: C 17.35, H 1.29, N 9.82;
elemental analysis calcd (%) for [AgACHTUNGRE(pyz)ClO4]1, C4H4N2AgClO4 : C
16.72, H 1.40, N 9.75; found: C 16.51, H 1.19, N 9.82; elemental analysis
calcd (%) for [AgACHTUNGRE(pyz)1.5CF3SO3]1, C7H6N3AgF3SO3 : C 22.29, H 1.60, N
11.15; found: C 22.13, H 1.53, N 10.90.
Typical procedure for anion exchange in water: [Ag(4,4’-bipy)NO3]1
(100 mg; 0.36 mmol) was immersed in 0.2 m aqueous solution of NaBF4
(5 mL) at room temperature for 1–3 h. The mixture was filtered and the
powder washed three times with water (30 mL), dried in vacuo and characterised by PXRD, elemental analysis and IR spectroscopy.
Typical procedure for anion exchange in organic solvents: [Ag(4,4’bipy)NO3]1 (100 mg; 0.36 mmol) was immersed in 0.2 m CH3CN solution
of [nBu4N]BF4 (5 mL) at room temperature for 1–10 days. The mixture
was filtered and the powder was washed three times with CH3CN
(30 mL) dried in vacuo and characterised by PXRD, elemental analysis
and IR spectroscopy.
Crystal structure determinations: Single-crystal X-ray diffraction data for
[AgACHTUNGRE(anbp)NO3ACHTUNGRE(H2O)]1 were recorded at 120(2) K by using a Bruker
SMART APEXII CCD area detector diffractometer at Daresbury SRS
Station 9.8 (l = 0.6939 ); other datasets were collected at 150(2) K by
using a Bruker SMART APEX CCD area detector diffractometer using
graphite-monochromated MoKa radiation (l = 0.71073 ). The structures
were solved by direct methods using SHELXS 97[47] and refined by least
squares on F2 in SHELXL 97.[47] All non-hydrogen atoms were refined
anisotropically; the hydrogen atoms of the framework and solvent molecules were added geometrically and refined as part of a riding model.
Diffuse electron density in the pore cavities of {[Ag(4,4’-bipy)ACHTUNGRE(CF3SO3)]·CH3CN}1 was calculated and accounted for using
SQUEEZE[48] at 104 electrons per unit cell, but the chemical species cor-
FULL PAPER
responding to this was not identified. The detailed crystallographic data
and refinement details are given in the Supporting Information.
CCDC 723084 (1), 706796 (2), 707011 (3), 710883 (4), 710882 (5), 720470
(6) and 720469 for (7) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Results and Discussion
Structures of coordination polymers: In this study we have
focused on a family of coordination chain polymers representing the simplest topological type for these materials.
The linear rigid exo-bidentate N-donor ligands pyrazine and
4,4’-bipyridine (Figure 1 a) commonly used for construction
of polymeric complexes can effectively bridge two metal
centres to form an extended chain (Figure 1 b). Regardless
of the nature of the metal centre or the ligand, the metal:ligand ratio for most of the complexes investigated in this
study is 1:1, thus enabling a direct comparison of solution
properties of these compounds and facilitates the understanding of the mechanisms of inter-conversion between
these structures.
Single crystals of [AgACHTUNGRE(pyz)ClO4]1 (1) suitable for X-ray
diffraction studies were obtained by layering a methanolic
solution of pyrazine over an aqueous solution of AgClO4. In
the structure of 1 each AgI is coordinated by two nitrogen
donors from two pyrazine donors (AgN 2.190(7),
2.259(5) , N1-Ag-N4 165.84(11)o), generating a slightly un-
Figure 1. Structures of a) ligands and b) coordination complexes reported in this study. M = AgI, ZnII, CdII or HgII ; X = NO3, CF3SO3, CH3COO, Cl,
BF4 or ClO4.
Chem. Eur. J. 2009, 00, 0 – 0
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&3&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
dulating chain. Each AgI centre is also coordinated by two
O donors from two ClO4 ions (Ag1O3 2.6808(12) ),
which then cross-link pairs of chains into a two-dimensional
coordination polymer.
Slow cooling of a hot saturated solution of [Ag(4,4’-bipy)CF3SO3]1 in CH3CN afforded colourless single crystals
of {[Ag(4,4’-bipy)ACHTUNGRE(CF3SO3)]·CH3CN}1 (2) the structure of
which shows each AgI coordinated by two 4,4’-bipy ligands
(AgN 2.129(13), 2.132(13) , aN-Ag-N 179.2(5)8) to generate a 1 D polymer chain. The AgI centre is further coordinated at long range by an O centre from a CF3SO3 anion
(Ag1O2 B 2.92(2) ) with aO-Ag-N 88.1(5), 92.6(6)8. The
CF3SO3 anions are also involved in hydrogen bonding
through two F and two O centres from one anion to five
CH centres from three 4,4’-bipy ligands to form three C
H···F and two CH···O hydrogen-bond interactions (C···F,
3.36(3), 3.60(3), 3.30(2) ; C···O 3.29(2), 3.24(2) ), which
link four adjacent polymer chains to form a 3 D framework.
Single
crystals
of
{[Ag(4,4’-bipy)ACHTUNGRE(CH3CN)]ClO4·
0.5CH3CN}1 (3) suitable for X-ray analysis were obtained
by slowly cooling down the hot saturated solution of
[Ag(4,4’-bipy)ClO4]1 in CH3CN to room temperature. The
structure of {[Ag(4,4’-bipy)ACHTUNGRE(CH3CN)]ClO4·0.5CH3CN}1
shows each AgI linked to two 4,4’-bipy N donors (AgN
2.164(5), 2.169(5) ; aNAgN 178.47(18)8), to form a 1D
polymer chain with an angle of 23.6(8)8 between the two
pyridyl rings of the 4,4’-bipy ligand. The AgI ion is also
weakly bound by a molecule of CH3CN (Ag1N3 S
2.789(6) ). The ClO4 counteranions do not coordinate directly to the AgI ions, but are located between the polymeric
chains with the three O centres from one ClO4 interacting
through CH···O contacts with three CH moieties from
two 4,4’-bipyridine molecules of adjacent polymeric chains
(C···O 3.431(10), 3.452(9), 3.500(9) ), these hydrogen
bonds linking the 1 D chains into a 2 D neutral layer.
Single crystals of [AgACHTUNGRE(anbp)NO3ACHTUNGRE(H2O)]1 (5) were obtained by layering a solution of anbp in CH3CN over a solution of AgNO3 in water. The structure of 5 shows a square
planar coordination geometry at AgI bound by two N centres from two anbp ligands (AgN 2.152(4), 2.153(3) ) and
two O centres from NO3 (Ag1—O3 3.095(3) ) and H2O
(Ag1—O1W 2.683(3) ) at long range; aN4···Ag1···N24
aN···Ag1···O3
86.34(11),
90.01(11)8
176.28(15)8,
aN···Ag···O1W 91.33(12), 92.33(11)8. The H2O ligand is further hydrogen bonded to two NO3 (O···O 2.824(4),
2.838(5) ) to formally link 1 D polymeric chains through
side groups to form a 3 D framework. There are further interactions in this complex that may warrant examination—
Ag–p interactions to adjacent complexes ( 3.75 to 3.8 ),
as well as p-edge interactions between anthracene rings,
which may provide additional stabilisation to the 3 D structure.
Hydrothermal treatment of [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1 at
120 8C
for
64 h
afforded
{[Cd(4,4’-bipy)2ACHTUNGRE(H2O)2]ACHTUNGRE(NO3)2·4 H2O}1 (6) which shows CdII coordinated to four N
donors from four 4,4’-bipy ligands (CdN 2.3427(17),
2.3598(17), 2.3784(13) ) and by two O donors from two
&4&
www.chemeurj.org
water molecules (CdO 2.3063(13) ) to form an octahedral
complex. The four 4,4’-bipy ligands are bridged by CdII to
form an extended 2 D cationic layer. The different layers
pack in an A-B-A-B manner in the crystal lattice. Each coordinated water molecule is hydrogen bonded to two uncoordinated water molecules (O···O 2.675(2), 2.677(2) ) and
each uncoordinated water is hydrogen bonded to two
oxygen atoms from two NO3 anions (O···O 2.776(2),
2.775(3), 2.802(2), 2.861(2) ). Pairs of layers are linked by
these hydrogen bonds, through coordinated and uncoordinated water and NO3 anion to form a 3 D framework.
Crystals of {[Zn(4,4’-bipy)SO4ACHTUNGRE(H2O)3]·2 H2O}1 (7) were
obtained by hydrothermal treatment of {[Zn(4,4’-bipy)ACHTUNGRE(SO4)]·6 H2O}1 at 120 8C for 64 h. The structure of 7 shows
each ZnII is coordinated to two N donors from two 4,4’-bipy
ligands
(ZnN
2.146(3),
2.152(3) ,
aN···Zn···N
177.89(16)8), generating a slightly undulating chain. The
metal centre is also coordinated by an O donor from the
SO42 (Zn1O1 2.323(3) ) and by three water molecules
(ZnO 2.065(4), 2.094(4), 2.127(3) ) to form a distorted
mer-octahedral complex. The chains pack in a parallel fashion within each layer, but the chains in adjacent layers are
mutually rotated by an angle of 608. The different layers
thus pack in a symmetric A-B-C-A-B-C manner along the
hexagonal c-axis. Pairs of adjacent chains are linked by hydrogen bonding between SO42 anions and coordinated
water molecules (O···O 2.690(5) 2.779(5), 2.721(5), 2.732(5),
2.854(4) ). In addition, one O centre from the SO42 anion
forms a C-H···O contact with a pyridine ring (C9···O2
3.377(6) , aC···H···O 1618). Two uncoordinated water
molecules interact with SO42 through OH···O hydrogen
bonding (O···O 2.766(5), 2.843(5), 3.060(5) ) and with each
other through OH···O hydrogen bonding (O···O
2.817(6) ). These crystals readily lose solvent in air, as indicated by elemental analytical data.
The structures of the complexes [Ag(4,4’-bipy)NO3]1,[7a, 18]
[Ag(4,4’-bipy)BF4]1,[49a]
[AgACHTUNGRE(pyz)BF4]1,[49b]
[Ag[49c,d]
ACHTUNGRE(pyz)NO3]1,
[Zn(4,4’-bipy)Cl2]1,[50a,b,c] and [Zn(4,4’bipy)ACHTUNGRE(CH3COO)2]1[50d,e,f] have been reported previously and
PXRD patterns derived from these single-crystal analyses
have been used to analyze exchange products in this study.
Solubility of coordination polymers: Since coordination
polymers are comprised of repeating metal–ligand units and
have a high molecular weight, they tend to have low solubility in most common solvents.[28] We have found that in certain cases their solubility is low, but finite through breakup
of the polymer and dissolution of the components and small
oligomers, and this solubility can be measured in deuterated
solvents by 1H NMR spectroscopy from which the concentration of dissolved ligand can be estimated by comparing
the integral intensity of NMR peaks of the ligand (4,4’-bipy
or pyrazine) with the intensity of an NMR peak from a
known concentration of the internal standard 1,3,5-tribromobenzene.
As shown in Table 1, the complex [Ag(4,4’-bipy)NO3]1 is
soluble in CH3CN and water with its solubility reaching
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
FULL PAPER
Table 1. Correlation of solubility of [Ag(4,4’-bipy)NO3]1 with physicochemical properties of different solvents at 20 8C.
Solvents
Dielectric
constant[a]
e/e0
acetonitrile 36.2
water
78.5
methanol
33.0
chloroform 4.7
acetone
2.7
benzene
2.28
Dipole
Affinity of Ag +
[a]
for solvents
moment
m [D]
(log K1)[b]
Solubility of complexes [mmol L1]
( 2 %)
3.92
1.87
1.7
1.01
2.88
0
1.43
0.80
0.32
0.19
0
0
0.42
2
–
0.70
0.85
0.38
Table 3. Solubility of coordination polymers [M(4,4’-bipy)ACHTUNGRE(NO3)2]1 and
[Ag(L)NO3]1 (M = Zn2 + , Cd2 + or Hg2 + ; L = pyz, 4,4’-bipy, 3,4’-bipy,
anbp) at 20 8C.
[a] “Handbook of Chemistry and Physics” ed. D. R. Lide, 3rd edtion.
[b] “Critical Stability Constants” A. E. Martell, R. M. Smith.
1.43 mmol L 1 and 0.80 mmol L1, respectively, at saturation.
However, this complex appears to be totally insoluble in
benzene or acetone, as no signal for 4,4’-bipyridine can be
detected by NMR spectroscopy for samples of the complex
immersed in [D6]benzene and [D6]acetone for over 24 h
even after ultrasonic agitation. [Ag(4,4’-bipy)NO3]1 also
shows very low solubility in chloroform (Table 1). These results confirm that coordination polymers dissolve more
readily in solvents of higher dielectric constant and higher
polarity. Because solvation of metal cations can facilitate
the dissociation of polymeric chains in these complexes, the
ability of the solvent to coordinate to metal cations appears
to be an important factor. For example, in contrast to
[Ag(4,4’-bipy)NO3]1, [Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1 and [Cd(4,4’bipy)ACHTUNGRE(NO3)2]1 dissolve more readily in MeOH or water
than in CH3CN (Tables 1 and 2). This can be attributed to
Table 2. Solubility of AgI polymeric complexes with 4,4’-bipy in different
solvents [mmol L]1 at 20 8C.
[Ag(4,4’-bipy)NO3]1
[Ag(4,4’-bipy)BF4]1
[Ag(4,4’-bipy)CF3SO3]1
[Ag(4,4’-bipy)ClO4]1
H2O
CHTUNGRE[A mmol L1]
ACHTUNGRE(2 %)
CH3OH
[mmol L1]
ACHTUNGRE(2 %)
CH3CN
[mmol L1]
ACHTUNGRE(2 %)
0.80
0.66
0.65
0.19
0.30
0.36
1.1
0.19
1.43
12.1
11.74
7.24
the fact that ZnII and CdII, being hard Lewis acids, can be
solvated by O-donor solvents more readily than the softer
Lewis acid AgI. As a result, AgI complexes tend to have a
higher solubility in N-donor solvents such as CH3CN, while
complexes of ZnII and CdII tend to be more soluble in Odonor solvents such as water and alcohols.
The interaction between ligands and metal cations from
which the coordination polymer is built hinders the dissociation of the polymeric chains, owing to the requirement to
break coordinative bonds. The stronger the metal–ligand interaction the more difficult it is to break up and thus dissolve the coordination polymer and the lower the resultant
solubility. For example, in both MeOH and CH3CN, the solubility of coordination polymers with different ligands displays
the
trend
[AgACHTUNGRE(pyz)NO3]1 > [Ag(3,4’-bipy)-
Chem. Eur. J. 2009, 00, 0 – 0
NO3·H2O]1 > [Ag(4,4’-bipy)NO3]1 > [AgACHTUNGRE(anbp)NO3·2.5
ACHTUNGRE(H2O)]1 (Table 3) reflecting expected strengths of the Ag
N(heterocycle) bond. As expected, the solubility of coordi-
Coordination polymer
CH3OH
ACHTUNGRE[mmol L1]
ACHTUNGRE(2 %)
CH3CN
[mmol L1]
ACHTUNGRE(2 %)
[Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1
[Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1
[Hg(4,4’-bipy))ACHTUNGRE(NO3)2]1
[AgACHTUNGRE(pyz)NO3]1
[Ag(3,4’-bipy)NO3·H2O]1
[AgACHTUNGRE(anbp)NO3·2.5 H2O]1
28.20
5.44
0
1.63
1.02
0.14
0.09
0.04
0
18.6
4.47
0.23
nation polymers also exhibits a strong temperature depenACHTUNGREdence, increasing significantly with temperature. For example, the solubility of [Ag(4,4’-bipy)NO3]1 increases from
0.37 mmol L1 at 0 8C, to 0.80 mmol L1 at room-temperature
( 23 8C), to 1.4 mmol L1 at 40 8C in H2O. It is, therefore,
necessary to maintain a constant temperature to allow direct
comparisons of solubilities for different coordination polymers and to allow the monitoring of exchange processes.
Anion exchange processes: Anion exchange has been studied in detail for various coordination polymers in water and
in organic solvents. As many anions have strong, well-defined IR absorption bands, IR spectroscopy (Figure 2) has
been used to monitor ion exchange and to characterise complex products and mixtures. The extent of anion exchange
Figure 2. IR spectra of products of conversion of [Ag(4,4’-bipy)BF4]1 to
[Ag(4,4’-bipy)NO3]1 in the presence of 0.2 m [NO3] at room temperature
in different solvents: a) The final product [Ag(4,4’-bipy)NO3]1; exchange
in b) MeCN, c) MeOH, d) water, and e) benzene; f) starting complex
[Ag(4,4’-bipy)BF4]1. Positions of main absorption bands of NO3 (g)
and BF4 (d) anions.
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&5&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
can be estimated by comparing the relative intensity of IR
bands of the incoming and the outgoing anions. Since coordination polymers tend to be highly crystalline, PXRD is
also a useful tool for monitoring the transformation of one
crystalline phase to another (Figure 3). After immersing
Scheme 1. Interconversions of coordination polymers through solventmediated anion exchange in different solvents: a) H2O; b) CH3OH;
c) CH3CN. Double-headed arrows indicate reversible and single-headed
arrows irreversible processes.
Figure 3. PXRD of products of conversion of [Ag(4,4’-bipy)BF4]1 to
[Ag(4,4’-bipy)NO3]1 in the presence of 0.2 m NO3 at 20 8C in different
solvents: a) the final product [Ag(4,4’-bipy)NO3]1; b) in MeCN; c) in
MeOH; d) in water; e) in benzene; f) the initial complex [Ag(4,4’bipy)BF4]1.
by IR spectroscopy (Figure 4). These observations correlate
directly with the relative solubilities of starting and final
complexes in a particular solvent and reveal that a reversible inter-conversion between two complexes is possible only
if they have comparable solubilities in the same solvent. For
[Ag(4,4’-bipy)BF4]1 in different solvents containing 0.2 m
NO3 for more than 10 days, the product obtained from
polar solvents, such as CH3CN, C6H5CN, EtOH , MeOH or
H2O was identified by IR spectroscopic and PXRD analysis
as [Ag(4,4’-bipy)NO3]1. However, the isolated product obtained from less polar solvents such as C6H6 or acetone was
identified as [Ag(4,4’-bipy)BF4]1 by IR spectroscopic and
PXRD analysis. These results confirm that anion exchange
between [Ag(4,4’-bipy)NO3]1 and [Ag(4,4’-bipy)BF4]1 can
occur readily in CH3CN, C6H5CN, EtOH , MeOH and H2O.
However, this exchange does not take place in benzene or
acetone even after 10 days. This indicates that in a given solvent, anion exchange occurs only if the coordination polymer has a measurable solubility in this solvent and that
solid-state anion exchange, which might be expected for an
insoluble system, does not take place under these conditions.
The solubility of the metal–ligand polymer also has a significant effect on the reversibility of anion exchange. We
have compared the reversibility of anion exchange in AgI/
4,4’-bipy complexes in water, CH3CN and MeOH. The
anion exchange does appear to be reversible (Scheme 1) between coordination polymers with comparable solubilities in
a given solvent. However, anion exchange between [Ag(4,4’bipy)NO3]1 and [Ag(4,4’-bipy)ClO4]1,, although reversible
in MeOH, is irreversible in CH3CN or water as confirmed
Figure 4. IR spectra of products of conversion between [Ag(4,4’-bipy)ClO4]1 and [Ag(4,4’-bipy)NO3]1 in CH3CN, CH3OH or H2O at 20 8C at
[X] = 0.2 m (X = NO3 or ClO4): a) [Ag(4,4’-bipy)ClO4]1; b) reaction of
[Ag(4,4’-bipy)NO3]1 with ClO4 in H2O; c) reaction of [Ag(4,4’-bipy)ClO4]1 with NO3 in H2O; d) reaction of [Ag(4,4’-bipy)NO3]1 with
ClO4 in CH3OH; e) reaction of [Ag(4,4’-bipy)ClO4]1 with NO3 in
CH3OH; f) reaction of [Ag(4,4’-bipy)NO3]1 with ClO4 in CH3CN; g) reaction of [Ag(4,4’-bipy)ClO4]1 with NO3 in CH3CN; h) [Ag(4,4’bipy)NO3]1. Positions of main absorption bands of NO3 (g) and
ClO4 (d) anions.
&6&
www.chemeurj.org
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
FULL PAPER
example, the solubilities of [Ag(4,4’-bipy)NO3]1 and
[Ag(4,4’-bipy)ClO4]1 in MeOH are close to each other
(0.30 mmol L1 and 0.19 mmol L1 respectively, Table 2),
which ensures reversibility of inter-conversion between
these two complexes (Figure 5). However, in water,
Figure 6. IR spectra of products of conversion of [Ag(4,4’-bipy)ClO4]1 to
[Ag(4,4’-bipy)NO3]1 in water at room temperature at different concentrations of NO3 : a) [Ag(4,4’-bipy)NO3]1; b) with added 2 m NO3 ;
c) with added 0.2 m NO3 ; d) [Ag(4,4’-bipy)ClO4]1. Positions of main absorption bands of NO3 (g) and ClO4 (d) anions.
Figure 5. XPRD patterns of products of conversion between [Ag(4,4’-bipy)ClO4]1 and [Ag(4,4’-bipy)NO3]1 in MeOH at 20 8C at [X] = 0.2 m
(X = NO3 or ClO4): a) [Ag(4,4’-bipy)NO3]1; b) reaction of [Ag(4,4’-bipy)ClO4]1 with NO3 ; c) reaction of [Ag(4,4’-bipy)NO3]1 with ClO4 ;
d) [Ag(4,4’-bipy)ClO4]1.
[Ag(4,4’-bipy)NO3]1 is much more soluble than [Ag(4,4’-bipy)ClO4]1, which inhibits reversibility (Scheme 1). In fact,
no exchange was detected for the complex [Ag(4,4’-bipy)ClO4]1 with any anion in water. This complex is significantly
less soluble in water than any other complexes and so ClO4
anions within [Ag(4,4’-bipy)ClO4]1 cannot be exchanged for
any other anions (NO3, CF3SO3 or BF4) to form the
more soluble coordination polymers under these conditions.
This also applies to [Ag(4,4’-bipy)NO3]1 in CH3CN
(Scheme 1).
The above data confirm that anion exchange in these materials
occurs
through
a
solvent-mediated
recrystallization process rather than through a solid-state
mechanism with anion exchange driven by the relative solubilities of the complex pairs under investigation and occurring from the more to the less soluble component. However,
a less soluble complex can be converted to a more soluble
component if the ratio of the concentrations of incoming to
outgoing anion is sufficiently high to shift the equilibrium
(Scheme 1). This indicates that the efficiency of anion exchange can be controlled by adjustment of the molar ratios
of the two competing anions. Indeed, only a weak absorption band for NO3 anion appears in the IR spectra after
[Ag(4,4’-bipy)ClO4]1 was immersed in 0.2 m aqueous solution of NaNO3 at room temperature, suggesting that only a
small amount of ClO4 anions within the polymer crystal exchanged with NO3 under these conditions (Figure 6 c). By
Chem. Eur. J. 2009, 00, 0 – 0
increasing the concentration of NO3 to 2 m, the intensity of
the absorption band from NO3 can be increased considerably (Figure 6 b) indicating that more ClO4 anions have
been exchanged with NO3 at a higher concentration of the
latter anion.
We have also investigated the selectivity of anion exchange if several types of anions are present in the solution
phase (see the Supporting Information). When the complex
[Ag(4,4’-bipy)CF3SO3]1 is immersed in an equimolar mixture of NO3, ClO4 and BF4 in MeOH or water for 24 h,
only [Ag(4,4’-bipy)ClO4]1 was isolated as a final product.
However, other products of exchange can be detected by IR
spectroscopy, as intermediate products, before the mixture is
fully equilibrated. Characteristic absorption bands of all
four anions NO3 (n 1380 cm1), CF3SO3 (n = 1020,
1280 cm1), ClO4 (n = 1086 cm1) and BF4 (n = 1065 cm1)
are all observed for the non-equilibrated product,[34, 37, 41] indicating the transient formation and co-existence of three
different coordination polymers at an early stage of the solvent-mediated exchange process. However, the intensities of
bands due to NO3, BF4 and CF3SO3 decrease gradually
until they totally disappear after 1 h and all transition complexes converge and transform into the final product
[Ag(4,4’-bipy)ClO4]1. The selective formation of this complex is confirmed by PXRD revealing a single-crystalline
phase in the final product. If this anion exchange occurred
through a purely solid-state mechanism, the selectivity of
anion exchange might be related to the size of ions.[2, 41, 51, 52]
For example, smaller ions would enter the crystalline lattice
of a coordination polymer more readily than larger ions.
However, the above experiment demonstrates that [Ag(4,4’bipy)ClO4]1 is selectively formed in preference to the analogous NO3 or BF4 salts and as it is the least soluble of all
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&7&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
the complexes in water, the whole process is governed by
the solubility difference between complex products. Again,
it should be noted that the nature of the solvent is a very
important factor for anion exchange and a similar experiment carried out in CH3CN yields [Ag(4,4’-bipy)NO3]1, as it
is the least soluble in CH3CN. A further aspect to consider
is the issue of solvation of free anions in solution. The Hofmeister series or bias confirms[53, 54] the low relative hydration of ClO4 compared to other anions in this study and is
consistent therefore with the lack of exchange observed for
[Ag(4,4’-bipy)ClO4]1 in water.
Anion exchange reactions have also been investigated for
complexes of ZnII with 4,4’-bipyridine and for complexes of
AgI with pyrazine. Although these coordination polymers
are much more soluble than the corresponding complexes of
AgI with 4,4’-bipyridine, similar trends were observed, as
shown in Scheme 2 and Table 4. As observed for [Ag(4,4’bipy)X]1, all anion exchange reactions for the series
Scheme 2. Interconversion of coordination polymers through anion exchange in water: a) in silver-pyrazine coordination polymers; b) in zinc4,4’-bipyridine coordination polymers in water. [X] = 0.2 m (X = NO3,
BF4, CF3SO3, ClO4, Cl, OAc). Double-headed arrows indicate reversible and single-headed arrows irreversible processes.
coordination polymers such as [Zn4O(L)3] MOF-5 (H2L =
benzene-1,4-dicarboxylate) is sensitive to polar solvents
such as water and this may well reflect a degree of chemical
reactivity of this labile ZnII material with water.
Single-crystal and powder X-ray diffraction confirm that
the original framework structures are not maintained after
anion exchange. On the contrary, there are significant
changes involving the chemical bonding, the conformation
of ligand and polymer and the symmetry of the whole structure. For example, AgI···AgI interactions, which contribute
to the formation of the 3 D framework in [Ag(4,4’-bipy)NO3]1[7a, 18] , disappear after exchange with NO3 or other
anions (BF4, CF3SO3 or ClO4) in solution. Moreover, the
crystal structure can also change remarkably. For example,
the parallel polymeric chains in [Ag(4,4’-bipy)ClO4]1 or
[Ag(4,4’-bipy)CF3SO3]1 become perpendicular in [Ag(4,4’bipy)NO3]1[7a, 18] or [Ag(4,4’-bipy)BF4]1[49a] on exchanging
their anions with NO3 or BF4 in solution. On anion exchange from [Zn(4,4’-bipy)ACHTUNGRE(CH3CO2)2]1 to [Zn(4,4’-bipy)Cl2]1,[50a,b,c] the conformation of the polymer chains changes
from a 1 D double chain to 1 D zigzag chains and the space
group of the solid-state structure goes from P1̄ to C2/c. It
has to be noted that structural transitions are possible
within the solid state, and reversible dynamic behaviour of
porous coordination polymers has been reported.[56]
Cation and ligand exchange: We have also investigated
metal cation exchange and ligand exchange in these systems.
IR spectroscopy for these processes is not as informative as
for anion exchange, but PXRD confirms that cation and
ligand exchanges readily take place through the same solvent-mediated process (Figure 7 and 8; and the Supporting
Information). Loss of overall crystallinity in products and in-
Table 4. Solubility of AgI and ZnII coordination polymers in water at
20 8C.
Coordination polymer
Solubility in water
ACHTUNGRE[mmol L1] ( 2 %)
[AgACHTUNGRE(pyz)NO3]1
[AgACHTUNGRE(pyz)BF4]1
[AgACHTUNGRE(pyz)1.5CF3SO3]1
[AgACHTUNGRE(pyz)ClO4]1
[Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1
[Zn(4,4’-bipy)(Ac)2]1
[Zn(4,4’-bipy)1.5ACHTUNGRE(BF4)2ACHTUNGRE(H2O)2]1
[Zn(4,4’-bipy)Cl2]1
12.4
115.6
28.67
9.6
77.17
38.61
27.61
12.09
[Zn(4,4’-bipy)X2]1 (X = Cl, CH3COO, BF4 or NO3) and
[AgACHTUNGRE(pyz)X]1 (X = ClO4, CF3SO3, BF4 or NO3) are
driven from the more soluble to the less soluble complex
form and were found to be reversible only for pairs of coordination polymers of similar solubility. This confirms that
solubility-driven anion exchange and dynamic complex
transformations are potentially general features of coordination polymers. Recent work[55] has confirmed that the ZnII
&8&
www.chemeurj.org
Figure 7. PXRD patterns of products of conversion between [Zn(4,4’bipy)ACHTUNGRE(NO3)2]1 and [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1 in MeCN at 20 8C at [M] =
0.2 m [M = ZnII or CdII]: a) [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1; b) formation of
[Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1 from [Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1; c) formation of
[Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1 from [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1; d) [Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1.
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
Figure 8. PXRD patterns of products of conversion between [Ag(4,4’bipy)NO3]1 and [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1 in MeCN at 20 8C at [M] = 0.2 m
[M = AgI or CdII]: a) [Ag(4,4’-bipy)NO3]1; b) formation of [Ag(4,4’bipy)NO3]1 from [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1; c) formation of [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1 from [Ag(4,4’-bipy)NO3]1; d) [Cd(4,4’-bipy)ACHTUNGRE(NO3)2]1.
termediates in these transfer reactions is observed in broadening of PXRD patterns (Figure 7 c). These processes involve metal–ligand bond cleavage and are, therefore, much
less likely to occur through a solid-state mechanism. Indeed,
dissolution of the polymeric complexes is entirely feasible
since both ligands and cations can be readily solvated and
stabilised in solution. As for the anion exchange experiments, cation exchange can be reversible or irreversible
(Scheme 3) and is again related to the difference in solubility of different forms (Table 4). Unexpectedly, however, we
found that exchange of AgI ions in [Ag(4,4’-bipy)NO3]1 can
proceed reversibly with ZnII or CdII ions in CH3CN even
though there is a large difference in solubilities of these
complexes with the AgI species being significantly less soluble. This is probably due to a combination of the salt effect
and the common-ion effect, which can influence the solubility of the final and initial coordination polymers. The salt
Scheme 3. Interconversion of coordination polymers through cation exchange in different solvents: a) CH3OH; b) CH3CN. Double-headed
arrows indicate reversible and single-headed arrows irreversible processes.
Chem. Eur. J. 2009, 00, 0 – 0
FULL PAPER
effect makes coordination polymers more soluble in a solution of higher ionic strength, whereas the common-ion effect
makes them less soluble in a solution in the presence of the
same ions. Thus, the presence of anion/cation salt combinations affects the overall dielectric and polarity of the solvent
mix.
As for cation and anion exchange, ligand exchange has
been systemically investigated within the series of complexes [Ag(L)NO3]1 (L = pyz, 3,4’-bipy, 4,4’-bipy, anbp) in
MeOH and CH3CN. Most studies on exchange processes
within coordination polymers focused on anion exchange,[17–19, 28–38] and few on cation exchange.[57] So far, to
the best of our best knowledge, no report on direct ligand
exchange has been published, although exchange of guest
molecules (gas or solvent molecules) in porous polymers has
been reported.[58]
Most ligand exchange reactions cannot occur reversibly
(Scheme 4), because of the significant differences in solubility between complex pairs (Table 3). However, if the differ-
Scheme 4. Interconversion of coordination polymers through ligand exchange in different solvents: a) CH3OH; b) CH3CN. Double-headed
arrows indicate reversible and single-headed arrows irreversible processes.
ence in solubility is sufficiently low, ligands exchange can
occur reversibly, for example in the ligand exchange between [Ag(4,4’-bipy)NO3]1 and [AgACHTUNGRE(anbp)NO3·2.5 ACHTUNGRE(H2O)]1.
It is interesting to note that all ligand exchange processes
between complexes of 4,4’-bipyridine and pyrazine appeared
to be irreversible, with 4,4’-bipyridine complexes being significantly less soluble compounds than corresponding pyrazine complexes for all types of metal ions and anions. For
example, [Ag(4,4’-bipy)NO3]1 can be obtained from [AgACHTUNGRE(pyz)NO3]1 by ligand exchange in a 0.2 m MeOH or CH3CN
solution of 4,4’-bipyridine, whereas [AgACHTUNGRE(pyz)NO3]1 can not
be obtained from [Ag(4,4’-bipy)NO3]1 using the same concentration of pyrazine in a reverse reaction. This also reflects the expected stronger binding of 4,4’-bipy to AgI compared with pyz.
Interestingly, in all cases studied here, the structures of
coordination polymer obtained through exchange reactions
are the same as the structures of the corresponding materials synthesised directly from the free ligand and metal salt.
For example, the crystal structure of [Ag(4,4’-bipy)NO3]1,
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&9&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
formed from [AgACHTUNGRE(pyz)NO3]1 by ligand exchange, [Ag(4,4’bipy)ClO4]1 by anion exchange or [Zn(4,4’-bipy)ACHTUNGRE(NO3)2]1
by cation exchange is the same as that of [Ag(4,4’bipy)NO3]1 synthesised from AgNO3 and 4,4’-bipyridine in
acetonitrile, as verified by PXRD patterns.[7a, 18]
Microscopy study of exchange processes: Atomic force microscopy (AFM) and scanning electron microscopy (SEM)
have been used to monitor the exchange processes in coordination polymers. SEM images (Figure 9) and AFM images
(Figure 10) show that the surface and shape of crystals of
Figure 9. SEM images of crystals of [Ag(4,4’-bipy)NO3]1 before (a, b)
and after (c, d) anion exchange by immersion in a 0.2 m NaBF4 aqueous
solution for 24 hours.
[Ag(4,4’-bipy)NO3]1 change remarkably after exposure to a
0.2 m solution of NaBF4 or NaCF3SO3. The initial layered
structure of [Ag(4,4’-bipy)NO3]1 (Figure 9a,b) changes drastically over time when the crystal is immersed in a 0.2 m solution of NaBF4 and disappears completely after a 24 h exposure to the solution (Figure 9c,d). Environmental AFM
enables in situ visualization of the evolution of crystal morphology during exchange processes. AFM topography and
amplitude images (Figure 10) show that the layered morphology of [Ag(4,4’-bipy)NO3]1 crystals disappears gradually during exposure to a 0.2 m solution of NaCF3SO3. AFM
also confirms that a new, qualitatively different crystal phase
is formed on the surface of the original crystals (Figure 10),
which indicates an epitaxial crystallization process during
the transformation from [Ag(4,4’-bipy)NO3]1 to [Ag(4,4’-bipy)CF3SO3]1. According to the PXRD data (see the Supporting Information), the newly formed material is the crystalline complex [Ag(4,4’-bipy)CF3SO3]1. These observations
clearly indicate that the exchange processes in these one-dimensional coordination polymers are accompanied by recrystallization of one complex as another and that the epitaxial crystallization may play a major role in transformations of coordination polymers.
The examples given above imply that all transformations
in one-dimensional coordination polymers suspended in so-
&10&
www.chemeurj.org
Figure 10. AFM topography and amplitude images (taping mode) of the
surface of an [Ag(4,4’-bipy)NO3]1 crystal after exposure to a 0.2 m
NaCF3SO3 aqueous solution for 0 min, a) 3 D topography and b) amplitude at t = 0 min. Amplitude images (c–e) at 60, 63 and 66 min, respectively. f) 3 D Topography view of the surface at 66 min. Selected areas in
images (c–e) shows formation of the new crystalline phase. Scale bars
represent 500 nm.
lution can be viewed as chemical reactions of ion exchange,
where a less stable (i.e. more soluble) compound is converted into a more stable (i.e. less soluble) one when equilibrium is reached. These transformations can be described by
the Equations (1)–(3), for anion, cation and ligand exchange,
respectively, in which M, M1 and M2 are metal ions, L, L1
and L2 are ligands, X, X1 and X2 are anions and S is solvent.
MLX1ðsolidÞ þ X2 þ nS $½MSn þ þ L þ X1 þ X2 $
MLX2ðsolidÞ þ X1 þ nS
M1 LXðsolidÞ þ ½M2 Sn þ þ nS $½M1 Sn þ þ L þ X þ ½M2 Sn þ $
M2 LXðsolidÞ þ ½M1 Sn þ þ nS
ð2Þ
ML1 XðsolidÞ þ L2 þ nS $½MSn þ þ L1 þ X þ L2 $
ML2 XðsolidÞ þ L1 þ nS
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
ð1Þ
ð3Þ
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
FULL PAPER
In the case of anion exchange, the standard thermodynamic equilibrium constant KV describing the exchange process can be expressed as a ratio of the solubility product
constants K V
for starting and resultant complexes
sp
[Eqn. (4)]:
KV ¼
½MLX 2 ½Sn
½MLX2 ½X1 ½Sn
½MSn ½X1 ½L Ksp1
¼
n ¼
Ksp2
½MLX1 ½Sn
½MLX1 ½X2 ½S
½MSn ½X2 ½L
ð4Þ
This expression clearly illustrates that the extent of ion
exchange is related to the relative solubilities of coordination polymers, which is itself affected and controlled by the
strength of binding of the component ligand and anion to
the metal centre. The reaction quotient Q can be expressed
as [Eqn. (5)]:
½MLX2 ½X1 ½Sn ½X1 Q¼
¼
½MLX1 ½X2 ½Sn ½X2 ð5Þ
Therefore, the instantaneous derivative of Gibbs energy
for anion exchange is [Eqn. (6)]:
Dr GðTÞ¼ Dr GV ðTÞ þ RT ln Q
¼ RT ln K V þ RT ln Q
Ksp1
½X ¼ RT ln
þ RT ln 1
Ksp2
½X2 ð6Þ
This shows that in a given solvent the direction of exchange is mostly determined by the relative concentrations
of the two anions involved in the exchange process in the
solution phase. Thus, provided that the starting and final coordination polymers have comparable solubility in this solvent, the direction of ion exchange in coordination polymers
can be controlled by adjusting the concentrations of anions
X1 and X2 in solution, which is confirmed by our experimental measurements. However, this must be regarded as
only an approximate model for real exchange processes
since coordination polymers do not completely dissociate
into single molecules or ions when dissolved in solution.[59]
Mass spectrometric results of AgI-4,4’-bipyridine coordination polymers suggest that the composition of the solution
phase is more complex, as there are species consisting of
one or more cations coordinated with ligands and/or solvent
molecules present in solution. For example, mass spectrometry of [Ag(4,4’-bipy)CF3SO3]1, in CH3CN shows not only
peaks for the single free ligand 4,4’-bipy and free anion
CF3SO3, but also some larger fragments, such as [AgACHTUNGRE(CF3SO3)2] , [Ag2ACHTUNGRE(CF3SO3)5]3, [Ag(4,4’-bipy)]nn + and
[Ag(4,4’-bipy)2] + . Therefore, the solubility product calculated from the concentration of ligand present in solution is
not an accurate value, only an estimate. Nonetheless, Equations (4) and (6) explain the observed dependence of reversibility of ion exchange on the type of solvent, as both solubility product and constant Ksp values are strongly solvent
dependent. These equations also indicate that temperature
Chem. Eur. J. 2009, 00, 0 – 0
T can affect the exchange process since Ksp is temperaturedependent. Indeed, we observed that anion exchange from
[Ag(4,4’-bipy)NO3]1 to [Ag(4,4’-bipy)BF4]1 readily occurs
at room temperature, but it does not occur at 4 8C, as confirmed by IR spectroscopy (see the Supporting Information). Also, the same anion exchange process does not occur
in CHCl3 at room temperature, but does proceed at higher
temperature. Moreover, Equation (6) suggests that a greater
value of Ksp1/Ksp2 should lead to a higher percentage of conversion of coordination polymer 1 to polymer 2, which is illustrated by corresponding analytical data (Tables 5 and 6).
The conversion rate can reach 99 % for systems with a high
value of Ksp1/Ksp2, or it can be nearly zero for Ksp1/Ksp2 <
0.03.
Conclusions
All coordination polymers studied herein exhibit low but
measurable solubilities in many common solvents. Their solubility depends strongly not only on the physicochemical
properties of solvents such as dielectric constant, polarity
and the degree to which they coordinate to the metal cation,
but also on the interaction between components of coordination polymer and solvent molecule. For the first time, we
have demonstrated that all components of coordination
polymers, namely the cation, anion and ligands, can be exchanged through a solution phase mechanism and new crystalline materials can form under these conditions through
recystallisation. This study has revealed that the extent and
the reversibility of an exchange process are determined by
the ratio of solubility product constants Ksp1 and Ksp2 for the
starting and the resultant complexes respectively, which in
turn depends on the type of the solvent and the temperature. We have shown that the extent of anion exchange is effectively controlled by the ratio of the concentrations of incoming ions and outgoing ions. These findings improve our
understanding of the nature of coordination polymers and
the dynamics of their interactions with solvents and reagents, which has important implications for synthesis of
polymers and for further development of practical applications of these as functional materials. Indeed, this work also
highlights that coordination polymers, especially those of
labile metal ions such as AgI, ZnII CdII, HgII and first-row
transition ions, can show significant solubility and solvation
and are not totally insoluble. These results of course do not
preclude an exclusive solid-state mechanism, for example,
for anion exchange in a highly connected 2 D or 3 D framework incorporating non-labile metal–ligand binding. However, over extended periods of many hours or days, even apparently “insoluble” polymers still may, in principle, undergo
solvent-mediated metal cation, anion or ligand exchange
through localised solubilisation at the surface of the crystalline material, which might otherwise appear spectroscopically, analytically and visually to be insoluble. In the absence of
definitive microscopic studies such as AFM or SEM, assign-
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&11&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
Table 5. Extent of anion exchange in water for [Ag(4,4’-bipy)X]1 at 20 8C, calculated on the basis of the elemental analytical data.
Anion exchange
[Ag(4,4’-bipy)X]1
from
from
from
from
from
from
from
from
from
from
from
from
NO3 to BF4
NO3 to CF3SO3
NO3 to ClO4
BF4 to NO3
BF4 to CF3SO3
BF4 to ClO4
CF3SO3 to NO3
CF3SO3 to BF4
CF3SO3 to ClO4
ClO4 to NO3
ClO4 to BF4
ClO4 to CF3SO3
solubility of starting complex
(S1) [mmol L1]
solubility of target complex
(S2) [mmol L1]
Ratio of solubili- Ratio of solubility product
ties S1/S2
constant Ksp1/Ksp2
Conversion
[%]
0.80
0.80
0.80
0.68
0.68
0.68
0.60
0.60
0.60
0.19
0.19
0.19
0.68
0.60
0.19
0.80
0.60
0.19
0.80
0.68
0.19
0.80
0.68
0.60
1.18
1.33
4.2
0.85
1.13
3.58
0.75
0.88
3.15
0.24
0.28
0.32
85.5
78.3
97.3
36.5
87.2
63.3
47.7
54.1
97.0
0
0
0
1.64
2.35
74.08
0.61
1.44
45.88
0.42
0.68
31.26
0.01
0.02
0.03
Table 6. Extent of anion exchange in acetonitrile for [Ag(4,4’-bipy)X]1 at 20 8C calculated on the basis of the elemental analytical data.
Anion exchange
[Ag(4,4’-bipy)X]1
from
from
from
from
from
from
from
from
from
from
from
from
NO3 to BF4
NO3 to CF3SO3
NO3 to ClO4
BF4 to NO3
BF4 to CF3SO3
BF4 to ClO4
CF3SO3 to NO3
CF3SO3 to BF4
CF3SO3 to ClO4
ClO4 to NO3
ClO4 to BF4
ClO4 to CF3SO3
solubility of starting complex
(S1) [mmol L1]
solubility of target complex
(S2) [mmol L1]
Ratio of solubili- Ratio of solubility product
ties S1/S2
constant Ksp1/Ksp2
1.43
1.43
1.43
12.1
12.1
12.1
11.74
11.74
11.74
7.24
7.24
7.24
12.1
11.74
7.24
1.43
11.74
7.24
1.43
12.1
7.24
1.43
12.1
11.74
0.01
0.01
0.20
8.46
1.03
1.67
8.21
0.97
1.62
5.06
0.60
0.60
ments for solid-state exchange processes in these systems
should be made with caution.
Acknowledgements
[4]
We gratefully acknowledge financial support from EPSRC, the University of Nottingham and the CVCP for an Overseas Research Students
(ORS) Scheme (to XC). ANK gratefully acknowledges the European
Science Foundation (ESF) and the Royal Society for support. MS gratefully acknowledges receipt of a Royal Society Wolfson Merit Award and
of an ERC Advanced Grant. We thank the EPSRC-funded synchrotron
crystallography service and its director Prof. W. Clegg for collection of
single-crystal diffraction data at Daresbury SRS Station 9.8.
[5]
[1] a) A. J. Blake, N. R. Champness, P. Hubberstey, W.-S. Li, M. A.
Withersby, M. Schrçder, Coord. Chem. Rev. 1999, 183, 117; b) A. N.
Khlobystov, A. J. Blake, N. R. Champness, D. A. Lemenovskii, A. G.
Majouga, N. V. Zyk, M. Schrçder, Coord. Chem. Rev. 2001, 222, 155.
[2] a) P. J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem. 1999, 111,
2798; Angew. Chem. Int. Ed. 1999, 38, 2638; b) B. Moulton, M. J.
Zaworotko, Chem. Rev. 2001, 101, 1629; c) B. F. Abrahams, P. A.
Jackson, R. Robson, Angew. Chem. 1998, 110, 2801; Angew. Chem.
Int. Ed. 1998, 37, 2656.
[3] a) A. J. Blake, N. R. Brooks, N. R. Champness, L. R. Hanton, P.
Hubberstey, M. Schrçder, Pure Appl. Chem. 1998, 70, 2351; b) N. R.
Champness, M. Schrçder, Curr. Opin. Solid State Mater. Sci. 1998, 3,
419; c) A. J. Blake, N. R. Champness, M. Crew, L. R. Hanton, S. Parsons, M. Schroder, J. Chem. Soc. Dalton Trans. 1998, 1533; d) A. J.
Blake, N. R. Brooks, N. R. Champness, M. Crew, L. R. Hanton, P.
&12&
www.chemeurj.org
[6]
[7]
[8]
[9]
106
106
106
605.50
1.09
4.66
553.39
0.91
4.25
129.55
0.216
0.216
0
0
0
99.8
62.2
72.4
99.4
98
92
98.9
49.6
39.1
Hubberstey, S. M. Parsons, M. Schroder, J. Chem. Soc. Dalton Trans.
1999, 2813; e) M. A. Withersby, A. J. Blake, N. R. Champness, P. A.
Cooke, P. Hubberstey, A. L. Realf, M. Schrçder, J. Chem. Soc.
Dalton Trans. 2000, 3261; f) N. R. Champness, J. Chem. Soc. Dalton
Trans. 2006, 877; g) D.-L. Long, A. J. Blake, N. R. Champness, M.
Schrçder, Chem. Commun. 2000, 2273.
a) M. J. Zaworotko, Chem. Commun. 2001, 1; b) M. J. Zaworotko,
Chem. Soc. Rev. 1994, 23, 283.
M. Kondo, M. Shimamura, S. Noro, S. Minakoshi, A. Asami, K.
Seki, S. Kitagawa, Chem. Mater. 2000, 12, 1288.
G. Tian, G.-S. Zhu, Q.-R. Fang, X.-D. Guo, M. Xue, J.-Y. Sun, S.-L.
Qiu, J. Mol. Struct. 2006, 787, 45.
a) F. Robinson, M. J. Zaworotko, J. Chem. Soc. Chem. Commun.
1995, 2413; b) A. N. Khlobystov, M. T. Brett, A. J. Blake, N. R.
Champness, P. M. W. Gill, D. P. ONeill, S. J. Teat, C. Wilson, M.
Schrçder, J. Am. Chem. Soc. 2003, 125, 6753; c) R. J. Hill, D.-L.
Long, N. R. Champness, P. Hubberstey, M. Schrçder, Acc. Chem.
Res. 2005, 38, 335; d) D.-L. Long, R. J. Hill, A. J. Blake, N. R.
Champness, P. Hubberstey, C. Wilson, M. Schrçder, Chem. Eur. J.
2005, 11, 1384.
a) O. M. Yaghi, G. Li, H. Li, Nature 1995, 378, 703; b) H. Li, M. Eddaoudi, T. L. Groy, O. M. Yaghi, J. Am. Chem. Soc. 1998, 120, 8571;
c) J. C. Rowsell, O. M. Yaghi, J. Am. Chem. Soc. 2006, 128, 1304;
d) D. Britt, D. Tranchemontagne, O. M. Yaghi, Proc. Natl. Acad. Sci.
USA 2008, 105, 11623.
a) X. Lin, A. J. Blake, C. Wilson, X. Z. Sun, N. R. Champness, M. W.
George, P. Hubberstey, R. Mokaya, M. Schrçder, J. Am. Chem. Soc.
2006, 128, 10745; b) X. Lin, J. Jia, X. Zhao, K. M. Thomas, A. J.
Blake, G. S. Walker, N. R. Champness, P. Hubberstey, M. Schrçder,
Angew. Chem. 2006, 118, 7518; Angew. Chem. Int. Ed. 2006, 45,
7358; c) J. Jia, X. Lin, A. J. Blake, N. R. Champness, P. Hubberstey,
L. Shao, G. Walker, C. Wilson, M. Schrçder, Inorg. Chem. 2006, 45,
8838; d) X. Lin, J. Jia, P. Hubberstey, M. Schrçder, N. R. Champ-
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Conversion
[%]
Chem. Eur. J. 0000, 00, 0 – 0
Transition-Metal Coordination Polymers
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
[30]
[31]
[32]
[33]
[34]
ness, CrystEngComm 2007, 9, 438; e) J. Jia, X. Lin, C. Wilson, A. J.
Blake, N. R. Champness, P. Hubberstey, G. Walker, E. J. Cussen, M.
Schrçder, Chem. Commun. 2007, 840; f) W. Yang, X. Lin, J. Jia,
A. J. Blake, C. Wilson, P. Hubberstey, N. R. Champness, M. Schrçder, Chem. Commun. 2008, 359; g) S. Yang, X. Lin, A. J. Blake, K. M.
Thomas, P. Hubberstey, N. R. Champness, M. Schrçder, Chem.
Commun. 2008, 6108; h) X. Lin, I. Telepeni, A. J. Blake, A. Dailly,
C. Brown, J. Simmons, M. Zoppi, G. S. Walker, K. M. Thomas, T. J.
Mays, P. Hubberstey, N. R. Champness, M. Schrçder, J. Am. Chem.
Soc. 2009, 131, 2159.
S. S.-Y. Chui, S. M.-F. Lo, J. P. H. Charmant, A. G. Orpen, I. D. Williams, Science 1999, 283, 1148.
a) S. Noro, S. Kitagawa, M. Kondo, K. Seki, Angew. Chem. 2000, 39,
2081; Angew. Chem. Int. Ed. 2000, 112, 2161; b) J.-P. Zhang, S. Kitagawa, J. Am. Chem. Soc. 2008, 130, 907; c) S. Ma, D. Sun, J. M. Simmons, C. D. Collier, D. Yuan, H.-C. Zhou, J. Am. Chem. Soc. 2008,
130, 1012.
M. Kondo, T. Yoshitomi, K. Seki, H. Matsuzaka, S. Kitagawa,
Angew. Chem. 1997, 109, 1844; Angew. Chem. Int. Ed. Engl. 1997,
36, 1725.
W. Mori, F. Inoue, K. Yoshida, H. Nakayama, S. Takamizawa, M.
Kishita, Chem. Lett. 1997, 1219.
D. Li, K. Kaneko, Chem. Phys. Lett. 2001, 335, 50.
H. J. Choi, T. S. Lee, M. P. Suh, Angew. Chem. 1999, 111, 1490;
Angew. Chem. Int. Ed. 1999, 38, 1405.
H. Li, C. E. Davis, T. L. Groy, D. G. Kelly, O. M. Yaghi, J. Am.
Chem. Soc. 1998, 120, 2186.
K. S. Min, M. P. Suh, J. Am. Chem. Soc. 2000, 122, 6834.
O. M. Yaghi, H. Li, J. Am. Chem. Soc. 1996, 118, 295.
B. F. Hoskins, R. Robson, J. Am. Chem. Soc. 1990, 112, 1405.
a) M. Fujita, Y. J. Kwon, S. Wasizhu, K. Ogura, J. Am. Chem. Soc.
1994, 116, 1151; b) T. Uemura, R. Kitaura, Y. Ohta, M. Nagaoka, S.
Kitagawa, Angew. Chem. 2006, 118, 4218; Angew. Chem. Int. Ed.
2006, 45, 4112; c) D. N. Dybtsev, A. L. Nuzhdin, H. Chun, K. P. Bryliakov, E. P. Talsi, V. P. Fedin, K. Kim, Angew. Chem. 2006, 118, 930;
Angew. Chem. Int. Ed. 2006, 45, 916.
J. S. Seo, D. Wahang, H. Lee, S. I. Jun, J. Oh, Y. J. Jeon, K. Kim,
Nature 2000, 404, 982.
K. S. Min, M. P. Suh, Chem. Eur. J. 2001, 7, 303.
E. Y. Lee, M. P. Suh, Angew. Chem. 2004, 116, 2858; Angew. Chem.
Int. Ed. 2004, 43, 2798.
a) T. M. Swager, Acc. Chem. Res. 1998, 31, 201; b) S. Ma, D. Sun, X.
Wang, H.-C. Zhou, Angew. Chem. 2007, 119, 2510; Angew. Chem.
Int. Ed. 2007, 46, 2458.
L. Mi, H. Hou, Z. Song, H. Han, Y. Fan, Chem. Eur. J. 2008, 14,
1814.
a) M. Albrecht M. Lutz, A. L. Spek, G. Van Koten, Nature 2000,
406, 970; b) J. A. Real, E. Andres, M. C. Munoz, M. Julve, T. Granier, A. Bousseksou, F. Varret, Science 1995, 268, 265.
a) P. Horcajada, C. Serre, G. Maurin, N. A. Ramsahye, F. Balas, M.
Vallet-Reg, M. Sebban, F. Taulelle, G. Frey, J. Am. Chem. Soc.
2008, 130, 6774; b)W. J. Rieter, K. M. Pott, K. M. L. Taylor, W. Lin,
J. Am. Chem. Soc. 2008, 130, 11 584.
L. Pang, B. B. Woodlock, X. T. Wang, C. Zheng, Chem. Commun.
2001, 1762.
S.-I. Noro, R. Kitaura, M. Kondo, S. Kitagawa, T. Ishii, H. Matsuzaka, M. Yamashita, J. Am. Chem. Soc. 2002, 124, 2568.
M. Du, Y.-M. Guo, S.-T. Chen, X.-H. Bu, S. R. Batten, J. Ribas, S.
Kitagawa, Inorg. Chem. 2004, 43, 1287.
G. B. Gardner, Y.-H. Kiang, S. Lee, A. Asgaonkar, D. Venkataraman, J. Am. Chem. Soc. 1996, 118, 6946.
M. Du, X.-J. Zhao, J.-H. Guo, S. R. Batten, Chem. Commun. 2005,
4836.
Z.-Z. Lin, F.-L. Jiang, D.-Q. Yuan, L. Chen, Y.-F. Zhou, M.-C.
Hong, Eur. J. Inorg. Chem. 2005, 1927.
a) J. Fan, L. Gan, H. Kawaguchi, W.-Y. Sun, K.-B. Yu, W.-X. Tang,
Chem. Eur. J. 2003, 9, 3965; b) L. Mi, H. Hou, Z. Song, H. Han, Y.
Fan, Chem. Eur. J. 2008, 14, 1814.
Chem. Eur. J. 2009, 00, 0 – 0
FULL PAPER
[35] O. M. Yaghi, H. Li, C. Davis, D. Richardson, T. L. Groy, Acc. Chem.
Res. 1998, 31, 474.
[36] H. J. Choi, M. P. Suh, J. Am. Chem. Soc. 2004, 126, 15844.
[37] O. Ohmori, M. Kawano, M. Fujita, J. Am. Chem. Soc. 2004, 126,
16292.
[38] J. J. Vittal, X. Yang, Cryst. Growth Des. 2002, 2, 259.
[39] G.-H. Cui, J.-R. Li, J.-L. Tian, X.-H. Bu, S. B. Batten, Cryst. Growth
Des. 2005, 5, 1775.
[40] O.-S. Jun, Y. J. Kim, Y. A. Lee, J. K. Park, H. K. Chae, J. Am. Chem.
Soc. 2000, 122, 9921.
[41] N. Malek, T. Maris, M. Simard, J. D. Wuest, J. Am. Chem. Soc. 2005,
127, 5910.
[42] A. N. Khlobystov, N. R. Champness, C. J. Roberts, S. J. B. Tendler, C.
Thompson, M. Schrçder, CrystEngComm 2002, 4, 426.
[43] C. Thompson, N. R. Champness, A. N. Khlobystov, C. J. Roberts, M.
Schrçder, S. J. B. Tendler, M. J. Wilkinson, J. Microsc. 2004, 214, 261.
[44] P. T. Cardew, R. J. Davey, Proc. R. Soc. London Ser. A 1985, 398,
415.
[45] C. Coudret, Synth. Commun. 1996, 26, 3543.
[46] K. Biradha, M. Fujita, J. Chem. Soc. Dalton Trans. 2000, 3805.
[47] G. M. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112.
[48] A. L. Spek, PLATON, A Multipurpose Crystallographic Tool, University of Utrecht, Utrecht, 1998.
[49] a) L. Carlucci, G. Ciani, D. M. Proserpio, private communication;
b) L. Carlucci, G. Ciani, D. M. Prosperio, A. Sironi, J. Am. Chem.
Soc. 1995, 117, 4562; c) R. G. Vranka, E. L. Amma, Inorg. Chem.
1966, 5, 1020; d) Yu. V. Kokunov, Yu. E. Gorbunova, A. S. Kazarinova, Russ. J. Inorg. Chem. 2005, 50, 1981.
[50] a) C. H. Hu, U. Englert, CrystEngComm 2001, 3, 91; b) Y.-C. Liang,
M.-C. Hong, R. Cao, W.-P. Su, Y.-J. Zhao, J.-B. Weng, Polyhedron
2001, 20, 2477; c) A. H. Fu, J. Y. Lu, X. Y. Huang, J. Li, J. Alloys
Compd. 2001, 319, 89; d) B. Conerney, P. Jensen, P. E. Kruger, B.
Moubaraki, K. S. Murray, CrystEngComm 2003, 5, 454; e) M. G.
Amiri, A. Morsali, Z. Anorg. Allg. Chem. 2006, 632, 2491; f) J. Kim,
U. Lee, B. K. Koo, Bull. Korean Chem. Soc. 2006, 27, 918.
[51] R. Custelcean, B. A. Moyer, Eur. J. Inorg. Chem. 2007, 1321.
[52] B. C. Tzeng, T. H Chiu, B. S. Chen, G. H. Lee, Chem. Eur. J. 2008,
14, 5237.
[53] D. Constantinescu, H. Weingartner, C. Hermann, Angew. Chem.
2007, 119, 9044; Angew. Chem. Int. Ed. 2007, 46, 8887.
[54] P. Westh, H. Kato, K. Nishikawa, Y. Koga, J. Phys. Chem. A 2006,
110, 2072.
[55] a) L. Huang, H. Wang, J. Chen, Z. Wang, J. Sun, D. Zhao, Y. Yan,
Microporous Mesoporous Mater. 2003, 58, 105; b) S. S. Kaye, A.
Dailly, O. M. Yaghi, J. R. Long, J. Am. Chem. Soc. 2007, 129, 14176.
[56] a) C. Serre, S. Bourrelly, A. Vimont, N. A. Ramsahye, G. Maurin,
P. L. Llewellyn, M. Daturi, Y. Filinchuk, O. Leynaud, P. Barnes, G.
Frey, Adv. Mater. 2007, 19, 2246; b) Y. Liu, J.-H. Her, A. Dailly,
A. J. R. Cuesta, D. A. Neumann, C. M. Brown, J. Am. Chem. Soc.
2008, 130, 11813; c) D. Tanaka, K. Nakagawa, M. Higuchi, S.
Horike, Y. Kubota, T. C. Kobayashi, M. Takata, S. Kitagawa, Angew.
Chem. 2008, 120, 3978; Angew. Chem. Int. Ed. 2008, 47, 3914; d) S.
Kitagawa, K. Uemura, Chem. Soc. Rev. 2005, 34, 109; e) J. A. R.
Navarro, E. Barea, A. Rodrguez-Diguez, J. M. Salas, C. O. Ania,
J. B. Parra, N. Masciocchi, S. Galli, A. Sironi, J. Am. Chem. Soc.
2008, 130, 3979.
[57] a) L. Mi, H. Hou, Z. Song, H. Han, Y. Fan, Chem. Eur. J. 2008, 14,
1814; b) S. Das, H. Kim, K. Kim, J. Am. Chem. Soc. 2009, 131, 3814;
c) P. Wang, J. Ma, Y. Dong, R. Huang, J. Am. Chem. Soc. 2007, 129,
10620; d) N. Malek, T. Maris, M. Simard, J. D. Wuest, J. Am. Chem.
Soc. 2005, 127, 5910.
[58] a) S. Hu, K. He, M. Zeng, H. Zou, Y. Jiang, Inorg. Chem. 2008, 47,
5218; b) M.-H. Zeng, X.-L. Feng, X.-M. Chen, Dalton Trans. 2004,
2217.
[59] C. A. Wheaton, M. C. Jennings, R. J. Puddephatt, J. Am. Chem. Soc.
2006, 128, 15370.
Received: March 27, 2009
Published online: && &&, 2009
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&13&
These are not the final page numbers! ÞÞ
M. Schrçder et al.
All the parts to make a whole: All the
components (anion, cation, ligand) in
AgI-N-heterocyclic coordination polymers, can be exchanged on contact
with a solution phase of a competing
component. The degree of reversibility
of these transformations is determined
by the ratio of the solubility product
constants for the starting and resultant
complexes, confirming that a “solidstate exchange mechanism” is not necessarily relevant to these systems.
Coordination Polymers
X. Cui, A. N. Khlobystov,* X. Chen,
D. H. Marsh, A. J. Blake, W. Lewis,
N. R. Champness, C. J. Roberts,
M. Schrçder* . . . . . . . . . . . . . . . . . &&&&—&&&&
Dynamic Equilibria in Solvent-Mediated Anion, Cation and Ligand
Exchange in Transition-Metal Coordination Polymers: Solid-State Transfer
or Recrystallisation?
&14&
www.chemeurj.org
2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!
Chem. Eur. J. 0000, 00, 0 – 0