Chalogen-Nitrogen Chemistry
... properties of these heavier chalcogen derivatives, especially in the case of tellurium. In addition, the lability of Se–N and Te–N bonds has led to applications of reagents containing these reactive functionalities in organic syntheses and, as a source of elemental chalcogen, in the production of me ...
... properties of these heavier chalcogen derivatives, especially in the case of tellurium. In addition, the lability of Se–N and Te–N bonds has led to applications of reagents containing these reactive functionalities in organic syntheses and, as a source of elemental chalcogen, in the production of me ...
Coordination Chemistry of Sugar
... 3.4 Equilibration times in experiments with D-glucose and D-glucose 6-phosphate ........ 101 3.5 Experiments with the ZnII(dien) metal fragment ........................................................ 103 3.6 Chelation preferences of sugars and sugar phosphates in complexes with the ZnII(dien) meta ...
... 3.4 Equilibration times in experiments with D-glucose and D-glucose 6-phosphate ........ 101 3.5 Experiments with the ZnII(dien) metal fragment ........................................................ 103 3.6 Chelation preferences of sugars and sugar phosphates in complexes with the ZnII(dien) meta ...
Adsorption of Metallic Ions onto Chitosan: Equilibrium and
... has a significant influence on the metal uptake rate for copper; but that it has only a slight influence on the adsorption rate of zinc and mercury in the range studied. Arsenic adsorption exhibited an interesting behaviour which depends strongly on the pH of the solution; the uptake increased at sh ...
... has a significant influence on the metal uptake rate for copper; but that it has only a slight influence on the adsorption rate of zinc and mercury in the range studied. Arsenic adsorption exhibited an interesting behaviour which depends strongly on the pH of the solution; the uptake increased at sh ...
Manganese catalysts in homogeneous oxidation reactions Brinksma
... tyrosine residue with O2 whereby H2O2 is released.35 Many functional GOase model complexes were developed and studied.36 Stack et al. synthesised a number of copper complexes with diimine-diphenolate ligands.37 Binaphthyl units were incorporated as backbone of the ligand changing a square-planar coo ...
... tyrosine residue with O2 whereby H2O2 is released.35 Many functional GOase model complexes were developed and studied.36 Stack et al. synthesised a number of copper complexes with diimine-diphenolate ligands.37 Binaphthyl units were incorporated as backbone of the ligand changing a square-planar coo ...
Hypervalent Iodine Reagents in High Valent Transition Metal
... to being at the forefront of modern catalytic method development. This approach has enabled transformations complimentary to those possible via traditional manifolds, most prominently carbon-heteroatom bond formation. Key to the advancement of this chemistry has been the identification of oxidants t ...
... to being at the forefront of modern catalytic method development. This approach has enabled transformations complimentary to those possible via traditional manifolds, most prominently carbon-heteroatom bond formation. Key to the advancement of this chemistry has been the identification of oxidants t ...
Outline
... or cyclophanes and appropriate metal ions. The selective heteroleptic preferring to homoleptic complexation is ascribed to recognition motif and maximun site ...
... or cyclophanes and appropriate metal ions. The selective heteroleptic preferring to homoleptic complexation is ascribed to recognition motif and maximun site ...
Plasmonic Doped Semiconductor Nanocrystals: Properties
... The damping is indirectly related to the width of the plasmon resonance. The quality factor of an LSPR mode is defined by the ratio of the LSPR peak energy and the full width at half maximum (FWHM) of the resonance peak.[11,56] It generally describes the quality of a specific LSPR mode: the stronger ...
... The damping is indirectly related to the width of the plasmon resonance. The quality factor of an LSPR mode is defined by the ratio of the LSPR peak energy and the full width at half maximum (FWHM) of the resonance peak.[11,56] It generally describes the quality of a specific LSPR mode: the stronger ...
D. Bagchi, S. Chaudhuri, S. Sardar, S. Choudhury, N. Polley, P
... samples. It has to be noted that BQ attached curcumin structure might not be similar to that of metallo curcumin complexes but excited state electron transfer timescale is similar due to proximity between two entities in both the cases. Thus, the shorter timescale in presence of metal ions can be ra ...
... samples. It has to be noted that BQ attached curcumin structure might not be similar to that of metallo curcumin complexes but excited state electron transfer timescale is similar due to proximity between two entities in both the cases. Thus, the shorter timescale in presence of metal ions can be ra ...
Reactions of 1, 10-phenanthroline with hydrogen, lithium, sodium
... The effect of these factors on stability and other properties of chelates have been reviewed by Kartell and Calvin (18, chapter 5)• Certain trends were established in studies of the correlation of stability constants with ion ization potential, charge and radius of metal ion, and aqua tion. The ma ...
... The effect of these factors on stability and other properties of chelates have been reviewed by Kartell and Calvin (18, chapter 5)• Certain trends were established in studies of the correlation of stability constants with ion ization potential, charge and radius of metal ion, and aqua tion. The ma ...
+ H 2 O(l) - Knockhardy
... the attraction extends to the shared pair of electrons in water’s O-H bonds the electron pair is pulled towards the O, making the bond more polar this makes the H more acidic (more d+) it can then be removed by solvent water molecules to form H3O+(aq). ...
... the attraction extends to the shared pair of electrons in water’s O-H bonds the electron pair is pulled towards the O, making the bond more polar this makes the H more acidic (more d+) it can then be removed by solvent water molecules to form H3O+(aq). ...
+ H 2 O(l) - Knockhardy
... the attraction extends to the shared pair of electrons in water’s O-H bonds the electron pair is pulled towards the O, making the bond more polar this makes the H more acidic (more d+) it can then be removed by solvent water molecules to form H3O+(aq). ...
... the attraction extends to the shared pair of electrons in water’s O-H bonds the electron pair is pulled towards the O, making the bond more polar this makes the H more acidic (more d+) it can then be removed by solvent water molecules to form H3O+(aq). ...
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).