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 ...
6. ACTIVATION OF THE PEPTIDE BOND FORMATION 6.1 INTRODUCTION
... the cis-glycylglycine (GG-cis) structure through TS2-cis. Similarly to TS3, both transitions structures present a fourth-membered ring as a consequence of the proton transfer process. Although TS2-trans and TS2-cis do not directly connect with the GG-trans and GG-cis isomers shown in Figure 6.4, res ...
... the cis-glycylglycine (GG-cis) structure through TS2-cis. Similarly to TS3, both transitions structures present a fourth-membered ring as a consequence of the proton transfer process. Although TS2-trans and TS2-cis do not directly connect with the GG-trans and GG-cis isomers shown in Figure 6.4, res ...
CHAPTER 1 INTRODUCTION 1.1 HYDRAZINE
... as hydrazinium perchlorate and nitrate are used as high energy oxidisers in propellants. Hence, thermal decomposition of these compounds has been investigated in detail (Pai Verneker et al 1976, Breisacher et al 1972 and Patil et al 1980). Thermal studies on hydrazinium sulphite hydrate (Patil et al ...
... as hydrazinium perchlorate and nitrate are used as high energy oxidisers in propellants. Hence, thermal decomposition of these compounds has been investigated in detail (Pai Verneker et al 1976, Breisacher et al 1972 and Patil et al 1980). Thermal studies on hydrazinium sulphite hydrate (Patil et al ...
Synthesis, characterization and bonding of Ba Li Sn
... interactions (Fig. 4). They showed that the main bonding states occur within the largest peak of the valence band in the DOS, between 211 and 28 eV, while the states of the same band above 28 eV are predominantly nonbonding, i.e. lone-pair like, as should be. The states above the Fermi level are cle ...
... interactions (Fig. 4). They showed that the main bonding states occur within the largest peak of the valence band in the DOS, between 211 and 28 eV, while the states of the same band above 28 eV are predominantly nonbonding, i.e. lone-pair like, as should be. The states above the Fermi level are cle ...
Giant Rugby Ball [{CpBnFe(η5-P5)}24Cu96Br96
... η1-coordination to Cu (10 × {CpBnFe(η5:1:1:1:1:1-P5)}); B, four P atoms feature a η1-coordination (6 × {CpBnFe(η5:1:1:1:1-P5)}); and C, in addition to a η1-coordination of three P atoms, two P−P edges surprisingly each show a η2-bond to copper (8 × {CpBnFe(η5:2:2:1:1:1-P5)}). Both σ-coordination mod ...
... η1-coordination to Cu (10 × {CpBnFe(η5:1:1:1:1:1-P5)}); B, four P atoms feature a η1-coordination (6 × {CpBnFe(η5:1:1:1:1-P5)}); and C, in addition to a η1-coordination of three P atoms, two P−P edges surprisingly each show a η2-bond to copper (8 × {CpBnFe(η5:2:2:1:1:1-P5)}). Both σ-coordination mod ...
Paper
... oxides and reduction of halides do not always provide required stoichiometry, homogenity, microstructural composition, high purity, desirable grain size and forms such as fibres, films and coating, foam and microporous membranes, submicron powders, as well as some multicomponent systems. Hence the d ...
... oxides and reduction of halides do not always provide required stoichiometry, homogenity, microstructural composition, high purity, desirable grain size and forms such as fibres, films and coating, foam and microporous membranes, submicron powders, as well as some multicomponent systems. Hence the d ...
Coordination Chemistry Reviews On the medicinal chemistry of gold
... 1000-fold selectivity compared to other related enzymes (glutathione reductase and glutathione peroxidase) [21]. Based on the different ligand structures of the many gold complexes, for which cell growth inhibiting properties have been observed, a unique mode of action of the agents is not likely to ...
... 1000-fold selectivity compared to other related enzymes (glutathione reductase and glutathione peroxidase) [21]. Based on the different ligand structures of the many gold complexes, for which cell growth inhibiting properties have been observed, a unique mode of action of the agents is not likely to ...
Direct Determination of the Ionization Energies of PtC, PtO, and
... ground state are in good accord with experiment.43-45 A schematic molecular orbital diagram for PtC, based on the one presented by Minaev, is shown in Figure 3. Minaev finds that the ground state is well described (83%) by the configuration 1σ22σ21π41δ43σ2. The 3Π0,1 states, formed by a 3σ f 2π exci ...
... ground state are in good accord with experiment.43-45 A schematic molecular orbital diagram for PtC, based on the one presented by Minaev, is shown in Figure 3. Minaev finds that the ground state is well described (83%) by the configuration 1σ22σ21π41δ43σ2. The 3Π0,1 states, formed by a 3σ f 2π exci ...
CE4501 Environmental Engineering Chemical Processes
... to become protonated (and thus volatile and toxic). The possible forms of cyanide and CN-, HCN, and Ni(CN)42-. The possible forms of Ni in addition to the cyanide complex are Ni2+, NiOH+, Ni(OH)2o, Ni(OH)3-T. First, let’s calculate the concentration of HCN in the absence of Ni(II): CT = [HCN] + [CN- ...
... to become protonated (and thus volatile and toxic). The possible forms of cyanide and CN-, HCN, and Ni(CN)42-. The possible forms of Ni in addition to the cyanide complex are Ni2+, NiOH+, Ni(OH)2o, Ni(OH)3-T. First, let’s calculate the concentration of HCN in the absence of Ni(II): CT = [HCN] + [CN- ...
Size-Controlled Synthesis and Optical Properties of Monodisperse
... lie in random orientations on the carbon support film, resulting in particle-to-particle variation diffractive contrast variation in low-resolution TEM images and in the observation of different zone axes in high-resolution TEM images. Projections of the rock-salt lattice along the [100] and [1̄10] ...
... lie in random orientations on the carbon support film, resulting in particle-to-particle variation diffractive contrast variation in low-resolution TEM images and in the observation of different zone axes in high-resolution TEM images. Projections of the rock-salt lattice along the [100] and [1̄10] ...
Analysis of structure–function relationships in cytochrome c oxidase
... metals with other molecules. In respect to the design of molecular catalysts and their long term stability this protection mechanism is of high importance and should be considered carefully. 4. Functional CcO inspired metal complexes The information gained by spectroscopy on the reaction mechanism o ...
... metals with other molecules. In respect to the design of molecular catalysts and their long term stability this protection mechanism is of high importance and should be considered carefully. 4. Functional CcO inspired metal complexes The information gained by spectroscopy on the reaction mechanism o ...
Conformational studies of aliphatic secondary ozonides
... of gaseous propene SOZ at 195 K. In this study only one conformer of the molecule had been observed, possessing the O-O half chair conformation and having a single methyl constituent in an equatorial position. The authors of this work do not rule out the presence of an axial conformer but they belie ...
... of gaseous propene SOZ at 195 K. In this study only one conformer of the molecule had been observed, possessing the O-O half chair conformation and having a single methyl constituent in an equatorial position. The authors of this work do not rule out the presence of an axial conformer but they belie ...
Text - Reading`s CentAUR
... and linking such units by Cu2+ ions, a modified Ni(CN)2 sheet structure can be assembled in which the copper atoms have squareplanar geometry and are coordinated only to cyanide ligands via nitrogen to generate an ordered sheet (Figure 1). # Although there are a number of examples of molecular speci ...
... and linking such units by Cu2+ ions, a modified Ni(CN)2 sheet structure can be assembled in which the copper atoms have squareplanar geometry and are coordinated only to cyanide ligands via nitrogen to generate an ordered sheet (Figure 1). # Although there are a number of examples of molecular speci ...
reactions of some transition metal ions cobalt
... • aqueous solutions contain the pink, octahedral hexaaquacobalt(II) ion • hexaaqua ions can also be present in solid samples of the hydrated salts • solutions of 2+ ions are weakly acidic but protons can be removed by bases... ...
... • aqueous solutions contain the pink, octahedral hexaaquacobalt(II) ion • hexaaqua ions can also be present in solid samples of the hydrated salts • solutions of 2+ ions are weakly acidic but protons can be removed by bases... ...
Photo-catalytic oxidation of a di-nuclear manganese centre in an
... PSII reaction centre. We have used bacterioferritin (BFR) (cytochrome b1) from Escherichia coli as the protein scaffold since it has several, inherently useful design features for engineering light-driven electron transport. Among these are: (i.) a di-iron binding site; (ii.) a potentially redox-act ...
... PSII reaction centre. We have used bacterioferritin (BFR) (cytochrome b1) from Escherichia coli as the protein scaffold since it has several, inherently useful design features for engineering light-driven electron transport. Among these are: (i.) a di-iron binding site; (ii.) a potentially redox-act ...
Triplet Emitters for OLED Applications. Mechanisms of Exciton
... hole transporting polymer. It is remarked that also several other matrix materials have successfully been tested with Ir(ppy)3 as emitter compound (e.g., see [40, 44]). However, in this latter case other materials of the adjacent layers might be required to obtain a fit of the potentials. (6) and (7 ...
... hole transporting polymer. It is remarked that also several other matrix materials have successfully been tested with Ir(ppy)3 as emitter compound (e.g., see [40, 44]). However, in this latter case other materials of the adjacent layers might be required to obtain a fit of the potentials. (6) and (7 ...
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).