- Free Documents
... wellknown class of predominantly thermochromic compounds. namely thermochromism and photochromism . while the CN bond lengths show that CN bonds are single tures are then reported as zwitterions instead of as ketoamine tautomers with no charge separation. while planar molecules of this type Schiff b ...
... wellknown class of predominantly thermochromic compounds. namely thermochromism and photochromism . while the CN bond lengths show that CN bonds are single tures are then reported as zwitterions instead of as ketoamine tautomers with no charge separation. while planar molecules of this type Schiff b ...
Characterization of metal ion-nucleic acid interactions in solution
... and radical cleavage experiments, mutational approaches, as well as kinetic isotope effects. In addition, spectroscopic techniques like EPR, lanthanide(III) luminescence, IR and Raman as well as various NMR methods are summarized. Aside from gaining knowledge about the thermodynamic properties on th ...
... and radical cleavage experiments, mutational approaches, as well as kinetic isotope effects. In addition, spectroscopic techniques like EPR, lanthanide(III) luminescence, IR and Raman as well as various NMR methods are summarized. Aside from gaining knowledge about the thermodynamic properties on th ...
Two-dimensional metal-organic networks as templates for the self
... for the organization of metal atoms and clusters on surfaces. We start with a systematic characterization of the metal-organic porous networks formed on Cu(111) by polyphenyl-dicarbonitrile molecules, and of the temperature dependence of the assembly process, leading to a variety of geometrical stru ...
... for the organization of metal atoms and clusters on surfaces. We start with a systematic characterization of the metal-organic porous networks formed on Cu(111) by polyphenyl-dicarbonitrile molecules, and of the temperature dependence of the assembly process, leading to a variety of geometrical stru ...
The Oxide Fluoride Chemistry of Bromine, Selenium and Sulphur
... In order to stabilise high oxidation states, strong covalent bonds are needed to restore electron density to the central atom. The strength of a bond, and its nature, depends on the relative electronegativities of the atoms in the bond. As the difference in the electronegativities of the two atoms i ...
... In order to stabilise high oxidation states, strong covalent bonds are needed to restore electron density to the central atom. The strength of a bond, and its nature, depends on the relative electronegativities of the atoms in the bond. As the difference in the electronegativities of the two atoms i ...
Interactions of Metal− Metal-Bonded Antitumor Active Complexes
... lines comparable to Rh2(µ-O2CCH3)4.22 The compound cisRh2(DTolF)2(O2CCF3)2(H2O)2 (Chart 1, structure e; DTolF) N,N′-p-tolylformamidinate) with two robust formamidinate and two labile trifluoroacetate bridging groups represents a favorable compromise between antitumor activity and toxic side effects. ...
... lines comparable to Rh2(µ-O2CCH3)4.22 The compound cisRh2(DTolF)2(O2CCF3)2(H2O)2 (Chart 1, structure e; DTolF) N,N′-p-tolylformamidinate) with two robust formamidinate and two labile trifluoroacetate bridging groups represents a favorable compromise between antitumor activity and toxic side effects. ...
Interaction of Alkaline Earth Metal Ions with Acetic and Lactic Acid in
... difference in the vibrational frequency of the asymmetric and symmetric C O O - vibrational m o d e s of the b o u n d carboxylate ion, relative to that of the free carboxylate ion [9]. Figure 2 shows the IR spectra of the calcium acetate solutions with varying ion concentrations in the frequency ra ...
... difference in the vibrational frequency of the asymmetric and symmetric C O O - vibrational m o d e s of the b o u n d carboxylate ion, relative to that of the free carboxylate ion [9]. Figure 2 shows the IR spectra of the calcium acetate solutions with varying ion concentrations in the frequency ra ...
The Use of XAFS to Distinguish between Inner- and Outer
... functional groups is a key factor that determines if a cation will adsorb onto the edge sites. For example, Pb 21 is a large cation that is highly polarizable and readily forms complexes with hydroxide-type functional groups, while Na 1 is a small more electronegative ion (less likely to share its e ...
... functional groups is a key factor that determines if a cation will adsorb onto the edge sites. For example, Pb 21 is a large cation that is highly polarizable and readily forms complexes with hydroxide-type functional groups, while Na 1 is a small more electronegative ion (less likely to share its e ...
Interaction of Alkaline Earth Metal Ions with Acetic and Lactic Acid in
... difference in the vibrational frequency of the asymmetric and symmetric C O O - vibrational m o d e s of the b o u n d carboxylate ion, relative to that of the free carboxylate ion [9]. Figure 2 shows the IR spectra of the calcium acetate solutions with varying ion concentrations in the frequency ra ...
... difference in the vibrational frequency of the asymmetric and symmetric C O O - vibrational m o d e s of the b o u n d carboxylate ion, relative to that of the free carboxylate ion [9]. Figure 2 shows the IR spectra of the calcium acetate solutions with varying ion concentrations in the frequency ra ...
Structures, spectra, and DNA-binding properties of
... imda anion and its derivatives serve as bioinorganic model compounds to illustrate conformational changes at the protein conformation for metal–protein centers in the absence or presence of appropriate substrates [32]. Also, the incorporation of methyl groups on the 5,6 positions of the phen ring wo ...
... imda anion and its derivatives serve as bioinorganic model compounds to illustrate conformational changes at the protein conformation for metal–protein centers in the absence or presence of appropriate substrates [32]. Also, the incorporation of methyl groups on the 5,6 positions of the phen ring wo ...
Davin, Thomas J. (2009) Computational chemistry of organometallic
... This thesis presents computational investigations of problems related to redox processes and structural rearrangement in inorganic systems. Density functional theory has been used to gain insight into the origin and nature of such reactions. The work presented concerns two main topics: hydrogenase-l ...
... This thesis presents computational investigations of problems related to redox processes and structural rearrangement in inorganic systems. Density functional theory has been used to gain insight into the origin and nature of such reactions. The work presented concerns two main topics: hydrogenase-l ...
Spectroscopic Characterization of the Surface of Iron Oxide
... with and bind to the nanocrystal surface via covalent, electrostatic, or coordination bonds (or some combination of all three), generally to the metal atoms. The lability of the surface ligand (ease with which it can be exchanged) depends on the strength of the binding interaction. The nanoparticles ...
... with and bind to the nanocrystal surface via covalent, electrostatic, or coordination bonds (or some combination of all three), generally to the metal atoms. The lability of the surface ligand (ease with which it can be exchanged) depends on the strength of the binding interaction. The nanoparticles ...
Transition metal-catalysed hydrogen transfer processes for C C and C N
... used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was exam ...
... used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was exam ...
Complexes. X-ray Structure of Rh1[C6H,(CH2NMe2),-o ,o`
... nitrogen donor groups. Since soft phosphorus ligands have room temperature unless stated otherwise. ‘H NMR spectra were usually been used in combination with these d8 centers, recorded on either a Varian T60 or a Bruker W 2 5 0 spectrometer; the choice of hard nitrogen ligands may appear a t first t ...
... nitrogen donor groups. Since soft phosphorus ligands have room temperature unless stated otherwise. ‘H NMR spectra were usually been used in combination with these d8 centers, recorded on either a Varian T60 or a Bruker W 2 5 0 spectrometer; the choice of hard nitrogen ligands may appear a t first t ...
Detection of Cysteine with Glutathione-capped
... of interactions among the AgGSH nanoparticles, Ni2+ ion, and amino acids and they do not interfere with the quantitative studies of Cys. The UV-Vis absorption spectra of Cys, AgGSH, AgGSHCys, AgGSH-Ni2+, Cys-Ni2+, and AgGSH-Ni2+-Cys solutions verified the AgGSH-Ni2+-Cys interactions. To further clar ...
... of interactions among the AgGSH nanoparticles, Ni2+ ion, and amino acids and they do not interfere with the quantitative studies of Cys. The UV-Vis absorption spectra of Cys, AgGSH, AgGSHCys, AgGSH-Ni2+, Cys-Ni2+, and AgGSH-Ni2+-Cys solutions verified the AgGSH-Ni2+-Cys interactions. To further clar ...
Word 97, TIFF, Unbekannt, Corel Draw, Windows
... A very interesting topic of nanotechnology today is the investigation of clusters exhibiting electrical quantum size effects, with the future aim of fabricating single-electron devices. One of the most suitable model compound is Au55 cluster [1], protected with various ligand shells of phosphorous- ...
... A very interesting topic of nanotechnology today is the investigation of clusters exhibiting electrical quantum size effects, with the future aim of fabricating single-electron devices. One of the most suitable model compound is Au55 cluster [1], protected with various ligand shells of phosphorous- ...
Synthesis and Structural Studies of Calcium and Magnesium
... calcium solids lie in the large metal diameters, the absence of energetically available dorbital to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray ...
... calcium solids lie in the large metal diameters, the absence of energetically available dorbital to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray ...
939 K - Scientific Research Publishing
... amount of interacting chromophores. The extent of interaction can be controlled by the chain length of R in 1 where an increasing size of the aliphatic group causes a progressive damping of the absorption at 525 nm and an increase of intensity at about 490 and 540 nm. We interpret the occurrence of ...
... amount of interacting chromophores. The extent of interaction can be controlled by the chain length of R in 1 where an increasing size of the aliphatic group causes a progressive damping of the absorption at 525 nm and an increase of intensity at about 490 and 540 nm. We interpret the occurrence of ...
Spin crossover
Spin Crossover (SCO), sometimes referred to as spin transition or spin equilibrium behavior, is a phenomenon that occurs in some metal complexes wherein the spin state of the complex changes due to external stimuli such as a variation of temperature, pressure, light irradiation or an influence of a magnetic field.With regard to a ligand field and ligand field theory, the change in spin state is a transition from a low spin (LS) ground state electron configuration to a high spin (HS) ground state electron configuration of the metal’s d atomic orbitals (AOs), or vice versa. The magnitude of the ligand field splitting along with the pairing energy of the complex determines whether it will have a LS or HS electron configuration. A LS state occurs because the ligand field splitting (Δ) is greater than the pairing energy of the complex (which is an unfavorable process).Figure 1 is a simplified illustration of the metal’s d orbital splitting in the presence of an octahedral ligand field. A large splitting between the t2g and eg AOs requires a substantial amount of energy for the electrons to overcome the energy gap (Δ) to comply with Hund’s Rule. Therefore, electrons will fill the lower energy t2g orbitals completely before populating the higher energy eg orbitals. Conversely, a HS state occurs with weaker ligand fields and smaller orbital splitting. In this case the energy required to populate the higher levels is substantially less than the pairing energy and the electrons fill the orbitals according to Hund’s Rule by populating the higher energy orbitals before pairing with electrons in the lower lying orbitals. An example of a metal ion that can exist in either a LS or HS state is Fe3+ in an octahedral ligand field. Depending on the ligands that are coordinated to this complex the Fe3+ can attain a LS or a HS state, as in Figure 1.Spin crossover refers to the transitions between high to low, or low to high, spin states. This phenomenon is commonly observed with some first row transition metal complexes with a d4 through d7 electron configuration in an octahedral ligand geometry. Spin transition curves are a common representation of SCO phenomenon with the most commonly observed types depicted in Figure 2 in which γHS (the high-spin molar fraction) is plotted vs. T. The figure shows a gradual spin transition (left), an abrupt transition with hysteresis (middle) and a two-step transition (right). For a transition to be considered gradual, it typically takes place over a large temperature range, even up to several hundred K, whereas for a transition to be considered abrupt, it should take place within 10 K or less.These curves indicate that a spin transition has occurred in a metal complex as temperature changed. The gradual transition curve is an indication that not all metal centers within the complex are undergoing the transition at the same temperature. The abrupt spin change with hysteresis indicates a strong cooperativity, or “communication”, between neighboring metal complexes. In the latter case, the material is bistable and can exist in the two different spin states with a different range of external stimuli (temperature in this case) for the two phenomena, namely LS → HS and HS → LS. The two-step transition is relatively rare but is observed, for example, with dinuclear SCO complexes for which the spin transition in one metal center renders the transition in the second metal center less favorable.There are several types of spin crossover that can occur in a complex; some of them are light induced excited state spin trapping (LIESST), ligand-driven light induced spin change (LD-LISC), and charge transfer induced spin transition (CTIST).