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Supramolecular Assemblies Built from Lanthanide Ammoniocarboxylates and Cucurbit[6]uril Pierre Thuéry CEA, IRAMIS, UMR 3299 CEA/CNRS, SIS2M, LCCEf, Bât. 125, 91191 Gif-sur-Yvette, France ABSTRACT: The reaction of lanthanide nitrates with different aminocarboxylic acids in the presence of cucurbit[6]uril (CB6) in water at room temperature yielded five novel complexes which were crystallographically characterized. The cerium complex involving the zwitterionic form of β-alanine (β-al), [Ce(β- al)(CB6)(NO3)(H2O)3]·2NO3·5H2O (1), is a molecular species in which the metal cation is bound to three carbonyl groups of CB6 and one monodentate carboxylate; the ammonium-bearing chain is encapsulated in the CB6 cavity, with the ammonium group hydrogen bonded to the uncomplexed portal. With a longer alkyl chain, 6-aminohexanoic acid (6-ah) leads to a different, dimeric structure in [Ce(6-ah)(CB6)(H2O)3]2·6NO3·17H2O (2), in which two metal ions connect two CB6 molecules and are further bridged by two carboxylate groups. The alkyl chains are included in the CB6 cavities and the ammonium groups are hydrogen bonded to the uncomplexed portals. Neighbouring, perpendicular dimers are associated through ammonium-water, water-carbonyl and CH···O(carbonyl) hydrogen bonds. Three complexes were obtained with the enantiopure α-amino acid L-methionine (L-me), all of which are chiral. In [Yb(L-me)(H2O)7]·CB6·3NO3·7H2O (3) and [Dy(L-me)(H2O)7]4[Dy(NO3)2(H2O)5]·4CB6·13NO3·29H2O (4), the metal ions are bound to one monodentate carboxylate and seven water molecules. The ammonium group is involved in hydrogen bonding with two CB6 molecules and the thiother-containing chain is included in the cavity of one CB6, with the sulphur atom shortest contact being with a ureido carbon atom. The supramolecular arrangement is columnar, the neighbouring chains being connected by hydrogen bonds formed by the ammonium groups. The neodymium complex [Nd(L-me)(CB6)(NO3)(H2O)3]2[Nd(L-me)(L-me – H)(H2O)5]2·8NO3·30H2O (5) displays two dinuclear units held by double carboxylate bridges. In one of them, the metal atoms are bound to CB6 and the L-me molecules are excluded from the CB6 cavities while, in the other, the metal atoms are not bound to CB6, but two Lme ligands are hydrogen bonded to CB6 portals and encapsulated. Together with previous results involving other aminocarboxylic acids, these complexes illustrate the different association modes between lanthanide ions, CB6 molecules and ammoniocarboxylates, which depend on the nature and geometry of the latter, and a balance between CB6 complexation to the lanthanide ion and ammoniocarboxylate/CB6 association through weak interactions. 1 INTRODUCTION Among the many remarkable properties of the cucurbit[n]uril macrocycles (CBn, Scheme 1),1 their ability to form host–guest complexes with ammonium ions2 has been put to particularly extensive use in the design of supramolecular assemblies such as rotaxanes and pseudorotaxanes3 as well as metal-containing polyrotaxanes and molecular necklaces.4 Ion–dipole and hydrogen bonding interactions involving the ammonium cation and the carbonyl groups of the cucurbituril portals are the dominant forces at play, with hydrophobic interactions adding an extra contribution when part of the ammonium-bearing molecule is included in the macrocycle cavity. Chiral guests have also been used5 and the possibility of using the achiral CB6 and CB7 hosts with a chiral inductor to achieve chiral recognition has been demonstrated.5a Chirality can also arise spontaneously from achiral ligands, as observed in some helical polyrotaxanes, which are however isolated as racemic mixtures.4c,g,h,j α-Amino acids are suitable guests and their interaction with CBs has been investigated;6 further, in their zwitterionic form, they possess a carboxylate group which can be used as a metal complexing site. This heterofunctionality has been used to build chiral one-dimensional assemblies in which lanthanide ions are bound to both L-cysteine and CB6,7 the latter being known to be a good complexant of 4f ions.8 Other ammoniocarboxylates have been used with lanthanide ions and CB6, such as iminodiacetate, which gives a complex displaying encapsulation of one uncoordinated carboxylic group.9 Recently, it was shown that the uranyl complexes formed with various ammoniobenzoates could serve as assemblers for CB6 molecules.10 The results presented herein are an extension of these previous studies to lanthanide complexes formed in the presence of CB6 with three aminocarboxylic acids: β -alanine (β -al) and 6-aminohexanoic acid (6-ah), which differ by the 2 length of the alkyl chain, and L-methionine (L-me), which is an enantiomerically pure, sulphurcontaining α-amino acid differing from the previously used L-cysteine by the alkyl sulphurbearing chain being longer by one carbon atom, and by the replacement of the thiol by a thioether group. EXPERIMENTAL SECTION Synthesis. Lanthanide nitrates (hexa- or penta-hydrates) were purchased from either Prolabo, Aldrich, Strem or Fisher Scientific, β-alanine and L-methionine from Aldrich, and 6aminohexanoic acid and cucurbit[6]uril pentahydrate from Fluka. Elemental analyses were performed by Analytische Laboratorien GmbH at Lindlar, Germany, or MEDAC Ltd. at Chobham, UK. [Ce(β -al)(CB6)(NO3)(H2O)3]·2NO3·5H2O (1). CB6·5H2O (11 mg, 0.01 mmol), a 10fold excess of Ce(NO3)3·6H2O (43 mg, 0.10 mmol), and a 20-fold excess of β -alanine (18 mg, 0.20 mmol) were dissolved in demineralized water (1.3 mL). The solution was then left to evaporate slowly, giving colourless crystals of compound 1 within two weeks (8 mg, 51% yield on the basis of CB6). Anal. Calcd for C39H59CeN28O31: C, 30.10; H, 3.82; N, 25.20. Found: C, 29.98; H, 3.98; N, 24.93%. [Ce(6-ah)(CB6)(H2O)3]2·6NO3·17H2O (2). CB6·5H2O (11 mg, 0.01 mmol), a 10-fold excess of Ce(NO3)3·6H2O (43 mg, 0.10 mmol), and a 20-fold excess of 6-aminohexanoic acid (26 mg, 0.20 mmol) were dissolved in demineralized water (2 mL). The solution was then left to evaporate slowly, giving colourless crystals of compound 2 in low yield within two weeks. 3 [Yb(L-me)(H2O)7]·CB6·3NO3·7H2O (3), [Dy(L-me)(H2O)7]4[Dy(NO3)2(H2O)5]·4CB6· 13NO3·29H2O (4), and [Nd(L-me)(CB6)(NO3)(H2O)3]2[Nd(L-me)(L-me – H)(H2O)5]2·8NO3· 30H2O (5). CB6·5H2O (11 mg, 0.01 mmol), a 10-fold excess of Ln(NO3)3·xH2O (x = 5 or 6; 45, 44 and 44 mg for Ln = Yb, Dy and Nd, respectively; 0.10 mmol), and a 20-fold excess of Lmethionine (30 mg, 0.20 mmol) were dissolved in demineralized water (1.5 mL). The solution was then left to evaporate slowly, giving colourless crystals of compounds 3–5 within about one month. For 3: 13 mg, 74% yield on the basis of CB6. Anal. Calcd for C41H75N28O37SYb: C, 28.02; H, 4.30; N, 22.32; S, 1.82. Found: C, 27.80; H, 4.27; N, 22.15; S, 1.64%. For 5: 6 mg, 24% yield on the basis of CB6. Anal. Calcd for C102H228N64Nd4O112S6: C, 24.94; H, 4.68; N, 18.25; S, 3.92. Found: C, 25.74; H, 4.40; N, 19.36; S, 4.06%. Crystallography. The data were collected at 150(2) K on a Nonius Kappa-CCD area detector diffractometer11 using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). The crystals were introduced into glass capillaries with a protecting “Paratone-N” oil (Hampton Research) coating. The unit cell parameters were determined from ten frames, then refined on all data. The data (combinations of ϕ- and ω-scans with a minimum redundancy of 4 for 90% of the reflections) were processed with HKL2000.12 Absorption effects were corrected empirically with the program SCALEPACK.12 The structures were solved by direct methods with SHELXS-97, expanded by subsequent Fourier-difference synthesis and refined by full-matrix (blocked matrix for compound 4) least-squares on F2 with SHELXL-97.13 All non-hydrogen atoms were refined with anisotropic displacement parameters, except for some atoms in 4 (see below), with restraints for some atoms in the disordered parts and/or solvent molecules. Some lattice water molecules were given partial occupancy factors in order to retain acceptable displacement parameters and/or to account for too close contacts. Some of the hydrogen atoms bound to oxygen and nitrogen 4 atoms were found on Fourier-difference maps (see below), and the carbon-bound hydrogen atoms were introduced at calculated positions. All hydrogen atoms were treated as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom (1.5 for CH3). Special details are as follows: Compound 1. The cerium atom is disordered over two sites, one at each CB6 portal, with occupancy parameters refined to values of 0.850(3) and 0.150(3), but the β -alanine, nitrate and water ligands bound to the main component Ce1 only were found. The hydrogen atoms bound to N1 could not be found due to the closeness of the minor cerium component, and they were introduced at calculated positions. The hydrogen atoms of two coordinated and two free water molecules only were found. The value of the refined Flack parameter14 is indicative of racemic twinning. Compound 2. The three nitrate counterions are disordered over seven positions located close to one another or to their image by symmetry, which were refined with occupancy parameters of 0.5 or 0.25. The hydrogen atoms of the ammonium group and coordinated water molecules were found on a Fourier-difference map. Compound 3. The hydrogen atoms bound to N1, N2 and four coordinated water molecules were found on a Fourier-difference map, but not those of the other water molecules. Compound 4. Four nitrate ions were given 0.5 occupancy factors in order to retain acceptable displacement parameters and to account for close contacts between them or with their image by symmetry. All non-hydrogen atoms were refined with anisotropic displacement parameters, but for six nitrogen and twelve oxygen atoms in badly resolved nitrate ions, and one water oxygen atom, which were refined with fixed isotropic displacement parameters. The hydrogen atoms bound to N1, N2 and N4 were found on a Fourier-difference map, but not those 5 of N3 and the water molecules. Some voids in the lattice likely indicate the presence of other, unresolved water solvent molecules. Compound 5. The monoclinic system is ruled out on the basis of the Rint value of 0.42. Although PLATON15 suggests a missing symmetry center with 86% fit, the correct space group is P1, due to the presence of the pure L-methionine enantiomorph. Pseudo-merohedral twinning with a binary axis parallel to c as a twin operator was taken into account (BASF = 0.11). The hydrogen atoms bound to N5 and N6 and those of nine coordinated water molecules were found on a Fourier-difference map, but not those bound to the other nitrogen and oxygen atoms. Crystal data and structure refinement parameters are given in Table 1 and selected bond lengths in Table 2. The molecular plots were drawn with ORTEP-316 and the views of the packings with VESTA.17 RESULTS AND DISCUSSION The two cerium complexes 1 and 2 present the common feature of inclusion of the ammoniocarboxylate ligand in the CB6 cavity, with differences which arise from the varying alkyl chain length. Complex 1, represented in Figure 1, involves the zwitterionic form of β alanine which is coordinated through the monodentate carboxylate group. Isomorphous complexes were obtained with La and Nd, but the lower quality of the crystals did not enable a satisfying structure refinement in these cases. The coordination sphere of the cerium ion is completed by three carbonyl groups from CB6, one bidentate nitrate ion and three water molecules to give a nine-coordinate environment of capped square antiprismatic geometry. The three carbonyl groups and one water molecule make one square face (O3, O5, O7, O18), while 6 the other comprises the nitrate ion and two water molecules (O15, O16, O19, O20), and the carboxylate atom O1 is in the capping position; the dihedral angle between the two faces is 2.7(2)°. The Ce–O(carboxylate) bond length of 2.340(7) Å matches the corresponding average value from the Cambridge Structural Database (CSD, Version 5.33),18 2.41(8) Å. There are few examples of lanthanide ions bound to three adjacent carbonyl groups of CB6: the first to have been reported involves the praseodymium ion, in a structure quite analogous to the present one, but for one cation being present at each portal and the replacement of the included β-al ligand by a nitrate ion,8d while the others involve the Ce, Pr, Yb and Lu cations with additional perrhenate ligands.8k The average Ce–O(carbonyl) bond length in the latter cases, 2.57(10) Å, matches the average value of 2.58(8) Å in 1, with in all cases the central bond shorter (by ca. 0.07–0.30 Å) than the lateral ones. The metal atom is displaced by 0.669(3) Å from the average portal plane, toward the outside. The included and disordered β-al molecule is located so that the ammonium group is close to the uncomplexed CB6 portal, with the nitrogen atom at 0.305(10) Å on the inside from the average portal plane. The ammonium protons were introduced at calculated positions (see Experimental Section) and their position is therefore subject to caution; however, they are indicative of the formation of hydrogen bonds with the uncomplexed carboxylate oxygen atom (O2), one carbonyl group (O8) and a water solvent molecule. The β-al ligand is thus just long enough to interact with one CB6 portal through its ammonium group while being coordinated to a metal atom located very close to the other portal. The packing is unexceptional, with columns of parallel molecules running along the b axis, these columns being offset with respect to one another along the a and c axes so as to enable a more compact arrangement. The cerium complex 2, which involves 6-ammoniohexanoate, is a centrosymmetric, dimeric, dinuclear complex in which two CB6 molecules are held together by the two metal 7 cations (Figure 2). The latter are doubly bridged by two carboxylate groups, the corresponding 6ah molecules occupying the cavities of the CB6 molecules. Each cation is further bound to two carbonyl groups from each CB6 and to three water molecules, thus lying in a nine-coordinate environment of tricapped trigonal prismatic geometry. The two trigonal faces are defined by the sets of atoms (O1, O3, O5) and (O2i, O9i, O11i) [dihedral angle 13.95(18)°], and the three water molecules (O15, O16, O17) occupy the capping sites. The cerium atom lies at 2.0235(15) Å from the average portal plane, while the carboxylate atoms O1 and O2 are very close to it, being displaced outside by 0.536(3) and 0.101(3) Å, respectively. Such an assembly of two doubly bidentate CB6 molecules held by two lanthanide ions has previously been described in the case of [Ce(CB6)(H2O)5]2·6Br·26H2O,8a in which however the two CB6 molecules are strongly tilted with respect to one another, while they are parallel in 2; comparable columnar, or merely dimeric arrangements in which CB6 molecules are held together by two lanthanide ions, with however a different denticity of CB6, were also found in cerium,8l neodymium,8e,l samarium and gadolinium8k complexes. The average Ce–O(carbonyl) bond length of 2.61(2) Å matches that in 1 and in the related cerium complex cited above [2.50(5) Å], while the average Ce–O(carboxylate) bond length of 2.37(4) Å is in agreement with the average value of 2.45(6) Å for similarly bridged cerium structures reported in the CSD. The 6-ah molecule extends in the CB6 cavity, which is indicative of hydrophobic interactions, and the ammonium group protrudes slightly out of the cavity at the uncomplexed portal, the nitrogen atom N1 being at 1.119(4) Å from the average portal plane. The ammonium group is involved in two hydrogen bonds with carbonyl oxygen atoms [N1···O4 2.795(5) Å, N1–H···O4 145°; N1···O14 2.936(5) Å, N1–H···O14 162°]; the third proton points outwards from the CB6 portal and it is hydrogen bonded to the water ligand oxygen atom O15 of a neighbouring molecule related to the first by a binary screw axis 8 [N1···O15j 3.171(4) Å, N1–H···O15j 169°; symmetry code: j = 3/2 – x, y – 1/2, 1/2 – z]. These two molecules, perpendicular to one another, are also held together by another hydrogen bond between the carbonyl atom O8 and the water ligand atom O17 [O17j···O8 2.935(4) Å, O17j– H···O8 145°], as well as by five CH···O(carbonyl) hydrogen bonds with H···O distances in the range 2.52–2.79 Å. The latter interactions are very frequent in crystal structures of CBs in which, notwithstanding their weakness, they play a prominent role which was recently examined in detail.1f The particularity of the present case is that each uncomplexed portal is involved in hydrogen bonds with each of the two CB6 molecules of the neighbouring unit. As a result of these interactions, layers parallel to the bc plane are formed, which are built from rows of molecules at right angles to one another (Figure 3). It appears in this case that, in contrast to 1, the longer chain of 6-ah permits the bridging of two lanthanide ions by the carboxylate group at one CB6 portal, while bringing the ammonium moiety slightly outside the other portal, in a position suitable for both intra- and intermolecular hydrogen bonding interactions. The crystal structures of three complexes with L-methionine could be determined, with the Nd, Dy and Yb cations (Eu gives a complex isomorphous to that of Nd, but the low quality of the crystals prevented a satisfactory structure refinement; La and Ce were tried, but did not give any crystalline material). These structures become more complicated as the size of the cation increases, and they will thus be discussed beginning with the smallest cation. All of these complexes crystallize in chiral space groups, the absolute configuration found from the value of the refined Flack parameter14 being in agreement with that of the enantiomorph used. The number of atoms in the asymmetric unit is thus quite large, resulting in 1966, 4077 and 2653 refined parameters for 3, 4 and 5, respectively. The asymmetric unit in the ytterbium complex 3 comprises two Yb ions and two CB6 molecules, which are however nearly identical (Figure 4). 9 Both metal cations are bound to one monodentate carboxylate group and to seven water molecules, the environment being square antiprismatic [dihedral angles of 0.6(3) and 2.7(5)° between the two square faces]. The average Yb–O(carboxylate) bond length of 2.274(1) Å is identical to the average value of 2.28(7) Å from the CSD. An intramolecular hydrogen bond links one water ligand to the uncomplexed carboxylate oxygen atom. While the metal cation is not directly bound to CB6, it is nevertheless held in its close proximity through the interactions between the L-me and aqua ligands with CB6. The ammonium nitrogen atoms are quite far from the CB6 portals, at 1.744(7) and 1.527(6) Å for N1 and N2, respectively, which brings the Yb1 and Yb2 atoms at distances of 4.052(4) and 4.156(4) Å. Only one hydrogen bond is formed by each L-me ligand with a carbonyl oxygen atom of the CB6 molecule in which it is included [N1···O19 2.742(8) Å, N1–H···O19 170°; N2···O31 2.672(8) Å, N2–H···O31 120°], but each is also bound to a carbonyl from the other molecule [N1···O33 3.048(8) Å, N1–H···O33 142°; N2···O29 2.842(8) Å, N2–H···O29 178°], while the third proton in each case is bound to a solvent water molecule. This gives rise to the formation of dimers, in which two parallel macrocycles [dihedral angle of 3.45(6)° between the proximal portals] are connected through weak interactions mediated by the ytterbium complexes. Although the protons of some of the water ligands were not found, the involvement of some of them (corresponding to O3, O7, O15 and O16) in hydrogen bonds with carbonyl groups (O23, O25, O37 and O39) can be inferred from the O···O distances which are in the range 2.651(8)–2.796(8) Å. Four of the water ligands directed away from CB6 in each complex unit, for some of which the protons were found, are hydrogen bonded to the carbonyl groups of neighbouring molecules [O···O distances in the range 2.625(9)–2.933(9) Å], giving rise to the formation of one-dimensional assemblies running along the b axis. The sulphur-containing chain is further included in the CB6 cavity, with the sulphur 10 atom being closer to the portal bound to the ammonium group [2.415(3) and 2.517(3) Å for S1 and S2, respectively] than to the other portal [3.701(3) and 3.596(3) Å], the terminal carbon atom being itself completely embedded [2.337(10) and 2.216(10) Å from the nearer portal]. The shortest contact made by the sulphur atom with the macrocycle involves an ureido carbon atom, at ca. 3.48 Å; analogous shortest contacts, with the same carbon atoms but a shorter distance of ca. 3.02 Å, were observed in the case of included perrhenate ions, when their position is not constrained by metal complexation.8k It is notable that, as in the case of chlorine encapsulation, these contacts involve the most electropositive atoms of the CB6 cavity lining.1f No other example of inclusion of a sulphur-containing chain in CB6 seems to exist. In complex 3, the ytterbium complexes are thus held close to the CB6 portal by ion–dipole interactions, three hydrogen bonds and hydrophobic interactions. Further hydrogen bonding by water ligands results in the formation of columns, which are held to one another by ammonium-carbonyl hydrogen bonds to give sheets parallel to (1 0 ī). This is at variance with the structures obtained with Lcysteine and the cations Nd, Eu, or Tb, in which the shorter thiol-bearing chain is not included in the CB6 cavity, but points sideways and is involved in some cases in a hydrogen bond with a carbonyl group. In the latter compounds, the lanthanide ion is complexed to one CB6 molecule, while the ammonium group is bound to a second molecule, thus generating a columnar onedimensional assembly. The longer thioether-bearing chain in 3 likely favours an arrangement involving hydrophobic interactions. The packing displays a compact arrangement of sheets, with no significant free space being present (Figure 5). The dysprosium complex 4 has many common features with 3, but the larger asymmetric unit comprises two dimeric units analogous to those in 3, and also two halves of dysprosium dinitrate pentahydrate moieties located around binary axes, as well as 13 uncomplexed nitrate 11 counterions and 29 free solvent molecules, which gives 464 non-hydrogen atomic positions. The two independent dimeric units will not be described in detail since their main features are analogous to those in 3, although slight differences exist in the finer details, such as in the orientation of the ammoniocarboxylates with respect to the other moieties (Figure 6). These differences result in the Ln···Ln separation in the dimers being smaller in 4 [12.5443(5) and 12.5253(5) Å] than in 3 [14.3075(4) Å]. As in 3, the shortest contacts between sulphur atoms and CB6 involve ureido carbon atoms, and they are in the range 3.66–3.86 Å. Each unit in the dimers pertains to a hydrogen bonded one-dimensional assembly parallel to the c axis, and sheets parallel to the bc plane are thus formed. In contrast to 3, these sheets are not closely packed, but are separated by the cationic [Dy(NO3)2(H2O)5]+ moieties, other counterions and solvent molecules (Figure 7). The neodymium complex 5 is quite different from 3 and 4, and the arrangement of the different ligands much less simple. This compound crystallizes in the chiral triclinic space group P1, with the two unit cell angles α and β close to 90°. The monoclinic system can be ruled out, but pseudo-merohedral twinning occurs, with a binary axis parallel to c as twin operator; structure refinement proceeds smoothly when the twin law is introduced (see Experimental Section). The asymmetric unit comprises four metal atoms, two CB6 molecules, four zwitterionic and two anionic L-me ligands (not differentiated), ten nitrate counterions and 46 water molecules, coordinated or free, which gives 294 non-hydrogen atomic positions. The four metal atoms are separated into two dinuclear units; in both of them, they are bridged by two L-me ligands through bridging bidentate carboxylates (Figure 8). In the first unit (Nd1, Nd2), each metal atom is additionally bound to a bidentate CB6 molecule, one chelating nitrate group and three water molecules, while, in the second (Nd3, Nd4) two extra L-me ligands, either monodentate or 12 chelating, and five water molecules complete the coordination spheres. Nd1, Nd2 and Nd4 are thus in nine-coordinate capped square antiprismatic environments and Nd3 is in an eightcoordinate square antiprismatic one. The average Nd···O(carboxylate) bond lengths of 2.42(2) and 2.61(10) Å, for monodentate and chelating coordination, respectively, are in agreement with the average values of 2.44(6) and 2.54(6) Å from the CSD. Two parallel CB6 molecules are thus held together by the dinuclear unit comprising Nd1 and Nd2, each being bound to one metal only, with an average Nd···O(carbonyl) bond length of 2.48(2) Å, in agreement with the value of 2.450(6) Å in the neodymium complex with L-cysteine. The two bridging L-me ligands point sideways and are not included in the CB6 cavities; one of the ammonium/amine groups likely forms a hydrogen bond with one carbonyl oxygen atom [N1···O57 2.843(16) Å], but the other bonds formed involve solvent water molecules or nitrate counterions. The other dinuclear unit is surrounded by four L-me ligands, either zwitterionic or anionic. As in the first unit, two L-me ligands are not included in CB6 molecules, and their ammonium/amine groups form hydrogen bonds with lattice water molecules. The two bridging L-me molecules have their thioethercontaining chain included in CB6 cavities and their ammonium groups, for which the protons have been found, are involved in two (N5) or one (N6) hydrogen bonds with carbonyl groups [N5···O38 2.786(13) Å, N5–H···O38 170°; N5···O40 2.752(14) Å, N5–H···O40 134°; N6···O48i 2.883(12) Å, N6–H···O48i 155°, symmetry code: i = x, y – 1, z – 1], while the other hydrogen bonds are with complexed or free water molecules. The nitrogen atoms N5 and N6 are respectively located at 1.625(11) and 1.828(9) Å from the average portal planes, and the sulphur atoms S3 and S4 at 2.414(6) and 2.352(5) Å from the same portals. As in complexes 3 and 4, the shortest sulphur-CB6 contacts involve ureido carbon atoms, at ca. 3.49–3.54 Å. The alternation of CB6 molecules with neodymium dinuclear units, either bonded or associated through weak 13 interactions, results in the formation of chains parallel to [0 1 1], with the CB6 molecules being tilted with respect to the chain axis (Figure 9); these chains are stacked so as to form layers parallel to the bc plane. The CB6-complexed neodymium atoms Nd1 and Nd2 are at 1.966(5) and 1.967(5) Å from the corresponding average portal plane, while the uncomplexed Nd3 and Nd4 are at distances in the range 4.260(6)–4.377(5) Å, comparable to those in 3 and 4. It is interesting to note that only the latter cations appear to be suitably located so as to enable encapsulation of the bridging L-me ligand, whose position with respect to the CB6 host does not change much throughout this series, with only second-sphere hydrogen bonding between the lanthanide aqua ligands and carbonyl groups. In contrast, the CB6-coordinated cations are seemingly too close to the portal to allow the formation of the specific L-me/CB6 interactions. This is reminiscent of the situation encountered in the lanthanide ion complexes with iminodiacetic acid and CB6,9 in which the metal ion is kept out of bonding distance of the carbonyl portal due to the interactions between the latter and the ammonium group. These results, which evidence some competition between metal and ammonium complexation, are to be compared to the recent findings that the ion–dipole and hydrogen bonding interactions between tryptophan or tryptamine and CB6 are sufficiently strong to displace coordinated magnesium ions.6g CONCLUSION The results reported herein are part of an investigation of the structures of the complexes formed by 4f or 5f element ions with ammoniocarboxylates in the presence of CB6.7,9,10 As expected, the most obvious variation in the series of complexes obtained is between uranyl and lanthanides. Although uranyl-lanthanide heterometallic complexes of CB6 with both cations 14 bound to carbonyl groups have been reported,8j recent results obtained with 1,2-ethanedisulfonate as an additional ligand have shown that CB6 preferentially binds the lanthanide cation, while the uranyl ion prefers sulfonate coordination.8m Although no complex with both cations and ammoniocarboxylates exists as yet, those obtained with each cation separately, although quite heterogeneous as to the nature and geometry of the ligands used, seem to confirm the lesser affinity of uranyl for CB6. Indeed, in the family of uranyl complexes with ammoniobenzoates,10 the uranyl ion is never bound to CB6, but only to the carboxylate groups (with the occurrence of additional oxo, hydroxo, formato or aqua ligands in some cases). The geometry of the complexes is thus determined by the arrangement of the ammoniocarboxylates around the uranyl mono-, dior tetranuclear central units, the CB6 molecules being held at the periphery through ion–dipole and hydrogen bonding interactions. In contrast, although the lanthanide ions are always bound to the carboxylate ligand, they can also be coordinated to CB6, as in the case of L-cysteine,7 β-al, 6ah and L-me, or the related case of 2-pyridylacetate.9 With iminodiacetate9 and L-me, they are only involved in second-sphere tethering to CB6 through the aqua ligands. The key factor in determining the specificities of the structure is the possibility for the ammoniocarboxylate molecule to bring the lanthanide ion close enough to CB6 for carbonyl coordination while retaining a position suitable for ammonium complexation and pendant group encapsulation. Several cases are thus possible: (i) with β -al and 6-ah, metal and ammonium complexation to CB6, and encapsulation, all coexist, with either one portal or both being involved; (ii) with Lcysteine, complexation to CB6 results in the ammonium being bound to the portal of a second CB6 molecule, thus giving a columnar assembly; (iii) in the case of iminodiacetate, ammonium coordination is only compatible with metal second-sphere bonding; (iv) finally, compound 5 illustrates two different situations and it is the only case in which some of the 15 ammoniocarboxylate ligands do not interact with CB6, which suggests that, in this case, there may exist a delicate balance between lanthanide complexation by CB6, associated with ammoniocarboxylate complete exclusion, and lanthanide second sphere tethering to CB6, associated with ammoniocarboxylate complexation and encapsulation. ACKNOWLEDGMENT. The Direction de l’Energie Nucléaire of the CEA is thanked for its financial support through the Basic Research Program RBPCH. ASSOCIATED CONTENT Supporting Information. Tables of crystal data, atomic positions and displacement parameters, anisotropic displacement parameters, and bond lengths and bond angles in CIF format. This information is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author E-mail: [email protected]. REFERENCES 1. (a) Freeman, W. A.; Mock, W. L.; Shih, N. Y. J. Am. Chem. Soc. 1981, 103, 7367. (b) Lee, J. W.; Samal, S.; Selvapalam, N.; Kim, H. J.; Kim, K. Acc. Chem. Res. 2003, 36, 621. (c) Kim, K.; Selvapalam, N.; Oh, D. H. J. Incl. Phenom. 2004, 50, 31. (d) Lagona, J.; Mukhopadhyay, P.; Chakrabarti, S.; Isaacs, L. Angew. Chem., Int. Ed. 2005, 44, 4844. (e) Isaacs, L. Chem. Commun. 2009, 619. (f) Bardelang, D.; Udachin, K. A.; Leek, D. M.; Margeson, J. C.; Chan, 16 G.; Ratcliffe, C. I.; Ripmeester, J. A. Cryst. Growth Des. 2011, 11, 5598. (g) Masson, E.; Ling, X.; Joseph, R.; Kyeremeh-Mensah, L.; Lu, X. RSC Adv. 2012, 2, 1213. 2. (a) Mock, W. L.; Shih N. Y. J. Org. Chem. 1983, 48, 3618. (b) Freeman, W. A. Acta Crystallogr., Section B 1984, 40, 382. (c) Mock, W. L.; Shih N. Y. J. Org. Chem. 1986, 51, 4440. (d) Jeon, Y. J.; Kim, S. Y.; Ko, Y. H.; Sakamoto, S.; Yamaguchi, K.; Kim, K. Org. Biomol. Chem. 2005, 3, 2122. (e) Vincil, G. A.; Urbach, A. R. Supramol. Chem. 2008, 20, 681. (f) Huang, W. H.; Zavalij, P. Y.; Isaacs, L. Org. Lett. 2008, 10, 2577. (g) Rekharsky, M. V.; Yamamura, H.; Mori, T.; Sato, A.; Shiro, M.; Lindeman, S. V.; Rathore, R.; Shiba, K.; Ko, Y. H.; Selvapalam, N.; Kim, K.; Inoue, Y. Chem.–Eur. J. 2009, 15, 1957. (h) Kim, Y.; Kim, H.; Ko, Y. H.; Selvapalam, N.; Rekharsky, M. V.; Inoue, H.; Kim, K. Chem.–Eur. J. 2009, 15, 6143. 3. (a) Jeon, Y. M.; Whang, D.; Kim, J.; Kim, K. Chem. Lett. 1996, 503. (b) Kim, K.; Jeon, W. S.; Kang, J. K.; Lee, J. W.; Jon, S. Y.; Kim, T.; Kim, K. Angew. Chem. Int. Ed. 2003, 42, 2293. (c) Sindelar, V.; Silvi, S.; Parker, S. E.; Sobransingh, D.; Kaifer, A. E. Adv. Funct. Mater. 2007, 17, 694. (d) Yin, J.; Chi, C.; Wu, J. Chem.–Eur. J. 2009, 15, 6050. 4. (a) Whang, D.; Jeon, Y. M.; Heo, J.; Kim, K. J. Am. Chem. Soc. 1996, 118, 11333. (b) Whang, D.; Kim, K. J. Am. Chem. Soc. 1997, 119, 451. (c) Whang, D.; Heo, J.; Kim, C. A.; Kim, K. Chem. Commun. 1997, 2361. (d) Roh, S. G.; Park, K. M.; Park, G. J.; Sakamoto, S.; Yamaguchi, K.; Kim, K. Angew. Chem. Int. Ed. 1999, 38, 638. (e) Lee, E.; Heo, J.; Kim, K. Angew. Chem. Int. Ed. 2000, 39, 2699. (f) Lee, E.; Kim, J.; Heo, J.; Whang, D.; Kim, K. Angew. Chem. Int. Ed. 2001, 40, 399. (g) Kim, K. Chem. Soc. Rev. 2002, 31, 96. (h) Park, K. M.; Whang, D.; Lee, E.; Heo, J.; Kim, K. Chem.–Eur. J. 2002, 8, 498. (i) Wang, Z. B.; Zhao, 17 M.; Li, Y. Z.; Chen, H. L. Supramol. Chem. 2008, 20, 689. (j) Zeng, J. P.; Cong, H.; Chen, K.; Xue, S. F.; Zhang, Y. Q.; Zhu, Q. J.; Liu, J. X.; Tao, Z. Inorg. Chem. 2011, 50, 6521. 5. (a) Rekharsky, M. V.; Yamamura, H.; Inoue, C.; Kawai, M.; Osaka, I.; Arakawa, R.; Shiba, K.; Sato, A.; Ko, Y. H.; Selvapalam, N.; Kim, K.; Inoue, Y. J. Am. Chem. Soc. 2006, 128, 14871. (b) Yuan, L.; Wang, R.; Macartney, D. H. Tetrahedron: Asymm. 2007, 18, 483. 6. (a) Buschmann, H. J.; Schollmeyer, E.; Mutihac, L. Thermochim. Acta 2003, 399, 203. (b) Bush, M. E.; Bouley, N. D.; Urbach, A. R. J. Am. Chem. Soc. 2005, 127, 14511. (c) Heitmann, L. M.; Taylor, A. B.; Hart, P. J.; Urbach, A. R. J. Am. Chem. Soc. 2006, 128, 12574. (d) Rajgariah, P.; Urbach, A. R. J. Incl. Phenom. Macrocycl. Chem. 2008, 62, 251. (e) Yi, J. M.; Zhang, Y. Q.; Cong, H.; Xue, S. F.; Tao, Z. J. Mol. Struct. 2009, 933, 112. (f) Urbach, A. R.; Ramalingam, V. Isr. J. Chem. 2011, 51, 664. (g) Danylyuk, O.; Fedin, V. P. Cryst. Growth Des. 2012, 12, 550. 7. Thuéry, P. Inorg. Chem. 2011, 50, 10558. 8. (a) Samsonenko, D. G.; Lipkowski, J.; Gerasko, O. A.; Virovets, A. V.; Sokolov, M. N.; Fedin, V. P.; Platas, J. G.; Hernandez-Molina, R.; Mederos, A. Eur. J. Inorg. Chem. 2002, 2380. (b) Samsonenko, D. G.; Sokolov, M. N.; Gerasko, O. A.; Virovets, A. V.; Lipkowski, J.; Fenske, D.; Fedin, V. P. Russ. Chem. Bull. 2003, 52, 2132. (c) Gerasko, O. A.; Sokolov, M. N.; Fedin, V. P. Pure Appl. Chem. 2004, 76, 1633. (d) Tripolskaya, A. A.; Mainicheva, E. A.; Mitkina, T. V.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. Russ. J. Coord. Chem. 2005, 31, 768. (e) Mainicheva, E. A.; Tripolskaya, A. A.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. Russ. Chem. Bull., Int. Ed. 2006, 55, 1566. (f) Liu, J. X.; Long, L. S.; Huang, R. B.; Zheng, L. S. Cryst. Growth Des. 2006, 6, 2611. (g) Liu, J. X.; Long, L. S.; Huang, R. B.; Zheng, L. S. Inorg. Chem. 2007, 46, 10168. (h) Gerasko, O. A.; Mainicheva, E. A.; Naumova, M. I.; 18 Yurjeva, O. P.; Alberola, A.; Vicent, C.; Llusar, R.; Fedin, V. P. Eur. J. Inorg. Chem. 2008, 416. (i) Gerasko, O. A.; Mainicheva, E. A.; Naumova, M. I.; Neumaier, M.; Kappes, M. M.; Lebedkin, S.; Fenske, D.; Fedin, V. P. Inorg. Chem. 2008, 47, 8869. (j) Thuéry, P. Inorg. Chem. 2009, 48, 825. (k) Thuéry, P. Inorg. Chem. 2009, 48, 4497. (l) Thuéry, P. Cryst. Growth Des. 2012, 12, 1632. (m) Thuéry, P. CrystEngComm, in the press, DOI: 10.1039/c2ce25091h. 9. Thuéry, P. Inorg. Chem. 2010, 49, 9078. 10. Thuéry, P. Cryst. Growth Des. 2012, 12, 499. 11. Hooft, R. W. W. COLLECT, Nonius BV: Delft, The Netherlands, 1998. 12. Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307. 13. Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112. 14. Flack, H. D. Acta Crystallogr., Section A 1983, 39, 876. 15. Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. 16. Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565. 17. Momma, K.; Izumi, F. J. Appl. Crystallogr. 2008, 41, 653. 18. Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380. 19 Table 1. Crystal Data and Structure Refinement Details 1 chemical formula M (g mol−1) cryst syst space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z Dcalcd (g cm−3) µ(Mo Kα) (mm−1) F(000) reflns collcd indep reflns obsd reflns [I > 2σ(I)] Rint params refined R1 wR2 S ∆ρmin (e Å−3) ∆ρmax (e Å−3) Flack parameter C39H59CeN28O31 1556.26 monoclinic P21 15.2093(5) 11.5727(4) 15.7952(4) 90 93.599(2) 90 2774.67(15) 2 1.863 0.947 1590 94585 10499 10172 0.021 912 0.072 0.196 1.075 −1.00 3.39 0.43(2) 2 3 C84H144Ce2N56O69 3322.79 monoclinic C2/c 34.5703(11) 21.2363(6) 21.7315(5) 90 127.1909(15) 90 12709.4(7) 4 1.737 0.837 6832 173673 16369 13649 0.031 1100 0.055 0.171 1.079 −1.54 2.84 − 20 C41H75N28O37SYb 1757.39 monoclinic P21 14.7871(1) 26.7248(3) 16.7471(2) 90 90.3591(5) 90 6618.03(12) 4 1.764 1.566 3596 197611 25021 23801 0.042 1966 0.057 0.154 1.098 −1.15 3.81 0.015(6) 4 5 C164H312Dy5N115O163S4 7444.03 monoclinic P2 25.4155(2) 18.8099(2) 29.8228(3) 90 93.6325(6) 90 14228.5(2) 2 1.738 1.458 7598 417600 53848 50057 0.032 4077 0.067 0.190 1.060 −2.94 2.96 0.058(6) C102H228N64Nd4O112S6 4912.80 triclinic P1 14.2583(7) 15.0998(4) 25.1467(12) 90.052(3) 90.186(2) 116.190(3) 4858.2(4) 1 1.679 1.239 2520 182415 36063 32731 0.041 2653 0.061 0.161 1.030 −1.33 2.88 0.005(11) Table 2. Environment of the Metal Atoms in Compounds 1–5: Selected Bond Lengths (Å) 1a 2b 3 a Ce1–O1 Ce1–O3 Ce1–O5 Ce1–O7 Ce1–O15 Ce1–O16 Ce1–O18 Ce1–O19 Ce1–O20 Ce–O1 Ce–O2i Ce–O3 Ce–O5 Ce–O9i Ce–O11i Ce–O15 Ce–O16 Ce–O17 Yb1–O1 Yb1–O3 Yb1–O4 Yb1–O5 Yb1–O6 Yb1–O7 Yb1–O8 Yb1–O9 Yb2–O10 Yb2–O12 Yb2–O13 Yb2–O14 Yb2–O15 Yb2–O16 Yb2–O17 Yb2–O18 2.340(7) 2.659(10) 2.468(6) 2.602(7) 2.667(8) 2.549(7) 2.492(8) 2.542(7) 2.541(8) 2.325(3) 2.410(3) 2.650(3) 2.606(3) 2.607(3) 2.585(3) 2.582(3) 2.539(3) 2.562(3) 2.273(5) 2.332(6) 2.314(6) 2.314(6) 2.315(5) 2.282(6) 2.405(6) 2.346(5) 2.275(5) 2.282(7) 2.419(7) 2.305(9) 2.218(12) 2.526(12) 2.285(7) 2.254(8) 4 Dy1–O1 Dy1–O3 Dy1–O4 Dy1–O5 Dy1–O6 Dy1–O7 Dy1–O8 Dy1–O9 Dy2–O10 Dy2–O12 Dy2–O13 Dy2–O14 Dy2–O15 Dy2–O16 Dy2–O17 Dy2–O18 Dy3–O19 Dy3–O21 Dy3–O22 Dy3–O23 Dy3–O24 Dy3–O25 Dy3–O26 Dy3–O27 Dy4–O28 Dy4–O30 Dy4–O31 Dy4–O32 Dy4–O33 Dy4–O34 Dy4–O35 Dy4–O36 Dy5–O37 Dy5–O38 Dy5–O40 Dy5–O41 Dy5–O42 Dy6–O43 Dy6–O44 Dy6–O46 Dy6–O47 Dy6–O48 2.311(5) 2.355(6) 2.378(6) 2.373(6) 2.420(6) 2.373(7) 2.401(6) 2.423(7) 2.322(5) 2.399(7) 2.376(6) 2.376(6) 2.390(6) 2.389(5) 2.403(6) 2.371(7) 2.294(6) 2.372(6) 2.365(6) 2.363(7) 2.403(6) 2.400(6) 2.402(6) 2.381(6) 2.300(5) 2.357(7) 2.342(6) 2.375(6) 2.395(6) 2.413(7) 2.381(6) 2.380(6) 2.438(12) 2.453(10) 2.432(13) 2.353(7) 2.410(10) 2.452(6) 2.526(9) 2.275(12) 2.378(6) 2.397(6) Values for the main cerium position only are given. b Symmetry code: 2: i = 3/2 – x, 1/2 – y, –z. 21 5 Nd1–O1 Nd1–O3 Nd1–O5 Nd1–O6 Nd1–O11 Nd1–O12 Nd1–O13 Nd1–O35 Nd1–O37 Nd2–O2 Nd2–O4 Nd2–O8 Nd2–O9 Nd2–O14 Nd2–O15 Nd2–O16 Nd2–O47 Nd2–O49 Nd3–O17 Nd3–O19 Nd3–O21 Nd3–O25 Nd3–O26 Nd3–O27 Nd3–O28 Nd3–O29 Nd4–O18 Nd4–O20 Nd4–O23 Nd4–O24 Nd4–O30 Nd4–O31 Nd4–O32 Nd4–O33 Nd4–O34 2.384(8) 2.421(7) 2.605(9) 2.558(8) 2.445(7) 2.461(7) 2.533(8) 2.451(7) 2.502(8) 2.428(8) 2.444(7) 2.563(7) 2.551(9) 2.475(7) 2.468(8) 2.523(8) 2.483(7) 2.494(8) 2.479(8) 2.379(8) 2.363(10) 2.544(8) 2.474(8) 2.465(8) 2.458(10) 2.478(8) 2.381(8) 2.512(7) 2.504(7) 2.709(8) 2.497(8) 2.459(8) 2.469(8) 2.477(9) 2.551(9) Figure Captions Figure 1. View of the cerium complex 1. Displacement ellipsoids are drawn at the 30% probability level. Counterions, solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Only one position of the disordered parts is represented. Figure 2. View of the cerium complex 2. Displacement ellipsoids are drawn at the 40% probability level. Counterions, solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry code: i = 3/2 – x, 1/2 – y, –z. Figure 3. View of the packing in complex 2. Counterions, solvent molecules and hydrogen atoms are omitted. The cerium coordination polyhedra are represented. Figure 4. View of the two independent units in the ytterbium complex 3. Displacement ellipsoids are drawn at the 30% probability level. Counterions, solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Figure 5. View of one sheet in the packing of complex 3. Counterions, solvent molecules and hydrogen atoms are omitted. The ytterbium coordination polyhedra are represented. 22 Figure 6. View of one dimeric unit in the dysprosium complex 4. Displacement ellipsoids are drawn at the 50% probability level. Carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Figure 7. View of the packing in complex 4, with the sheets viewed edge-on. Counterions, solvent molecules and hydrogen atoms are omitted. The dysprosium coordination polyhedra are represented. Figure 8. View of the neodymium complex 5. Displacement ellipsoids are drawn at the 30% probability level. Counterions, solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Figure 9. View of the packing in complex 5. Counterions, solvent molecules and hydrogen atoms are omitted. The neodymium coordination polyhedra are represented. 23 Scheme 1. Cucurbit[n]uril Figure 1 24 Figure 2 Figure 3 25 Figure 4 Figure 5 26 Figure 6 Figure 7 27 Figure 8 Figure 9 28 For Table of Contents Use Only Supramolecular Assemblies Built from Lanthanide Ammoniocarboxylates and Cucurbit[6]uril Pierre Thuéry Different association modes of lanthanide ions, cucurbit[6]uril, and ammoniocarboxylate molecules are observed, depending upon the nature and geometry of the latter. While the metal ion is always bound to the carboxylate group, the association of the ammoniocarboxylate to CB6 through weak interactions is not always compatible with carbonyl coordination. 29