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The studies have shown that anionic and cationic amphiphiles of unequal charge has coasssembled into small buckled vesicles. The strong electrostatic interaction between the +3 and -1 head groups has increased the cohesion energy of the amphiphiles and has favored the formation of two-dimensional, flat ionic domains on the vesicle surface, resulting in edges and a buckled shape.

The neutron scattering analysis approach is employed to explain the structure of the Cu[Mn.sub.2][O.sub.4] ions with two different Jahn-Teller ions at different sites. The mechanisms associated with the occurrence of the Cu and Mn ions at different atomic positions in the oxide spinel are also discussed.

The electronic band structures and optical gain of In[As.sub.1-x][N.sub.x]/GaAs pyramid quantum dots (QDs) are calculated by using the ten-band k.p model and the valence force field method. Larger QD has reached its saturation gain faster, but this saturation gain is smaller than that of smaller QDs and hence the trade-off between longer wavelength, maximum optical, saturation gain and differential gain is considered for selecting the appropriate QD size according to the specific application requirement.

The characterization of a random kinetic mechanism for the first two-electron oxidation reaction of the diheme enzyme MauG-dependent tryptophan tryptophylquinone (TTQ) biosynthesis is described. The kinetic mechanism of MauG-dependent TTQ biosynthesis was found to be distinct from that of the homologous diheme cytochrome c peroxidases that require a mixed valence state for activity.

Inert gas evaporation method is used for preparing Pd nanoparticles and their electronic structures are analyzed. The results have provided evidence of interplay of quantum confinement and coordination reduction.

Different multistate generalizations of a two-state (EVB) model for proton hopping between water molecules are used for analyzing the proton transfer (PT) mechanism in liquid water. The transition in real time is monitored, which has shown how the average structure is converted to a distorted [H.sub.5][O.sub.2.sup.+] cation constituting the transitional complex for proton hopping between water molecules.

N-heterocyclic carbene ligands with different steric bulk on the N-substituents are used to synthesize and characterize a series of asymmetrically disubstituted models of the active site of [FeFe]-hydrogenase. The results for [FeFe]-hydrogenase active site model provides insight into the features that contribute to the stability of the unique rotated structure of the [Fe.sup.I][Fe.sup.II] mixed valent [H.sub.ox] mimics.

The density functional theory calculations were used to explore the S=11 ground states of the [Mn.sup.7] family of mixed-valence complexes with a metal-centered hexagonal topology. The topology was observed to arise by spin frustration involving small differences in the magnitudes of the two weakest interactions controlling the alignment of the central spin which lead to formation of complex with maximum S = 16 ground state.

The band structure of direct-band gap semiconductors is described by using a 34 * 34 k.p model. The results have shown that Luttinger parameters, the k valence band parameter, the effective Lande factor g*, and the effective-masses in the X and L valleys have agreed well with the experimental data.

The studies of material trends related to the charge carrier transport at interfaces between the binary as well as some of the binary indium sulfides and CuI are reported. No valence band offset was observed in CuI/Cu[In.sub.5][S.sub.8] heterojunction and hence they could find potential applications as a diode.

Multistate empirical valence bond simulations are used for studying proton transport through gramicidin A channels embedded in two different lipid bilayers, glycerol 1-monooleate (GMO) and diphytanolphosphatidylcholine (DiPhPC). The quantitative and qualitative differences are discussed in terms of local bilayers structures, ordering of interfacial water and channel flexibility in the two environments.

The isotropic double-exchange interaction model is used to describe the valence delocalization (migration of the extra d hole over all three Cu centers) in the delocalized [Cu.sub.2.sup.7+] cluster. The delocalized model of hyperfine interaction explains the hyperfine structure [10 hyperfine lines with the relative intensities 1:3:6:10:12:12:10:6:3:1 and the interval a/3] of the EPR transitions in the triplet states that was observed in the EPR spectra of the [Cu.sub.3][(mu)3-S).sub.2] cluster.

Coronene is proposed to be 'superaromatic', but energetic, geometeric, and magnetic criteria of global and local aromaticity fail to support his proposal. However, [7,5,7,5,7,5]-isocoronene, which is a valence isomer, qualifies as superaromatic on the magnetic criterion, as verified by the excellent agreement with anisotropy and exaltation of magnetic susceptibility, while the energetic criterion shows that isocoronene is destabilized with respect to coronene.

A viable synthetic route is developed for a doubly unsaturated bicyclo[4.2.1]nonanyl sultam featuring the nitrogen at the bridgehead site and the sulfonamide sulfur on the single atom bridge. The direct irradiation of bicyclic dienyl sultam (9) resulted in valence isomerization to provide the endo-cyclobutene 30 and heating 9 with endo-bornyltriazolinedione in ethyl acetate solution gave rise to 33 and its diastereomer.

The proton spin-lattice relaxation measurements are used to determine the intramolecular electron transfer (ET) rates of the mixed-valence biferrocene monocation in various solvents and solvent dynamic contribution are analyzed on the basis of the Sumi-Marcus-Nadler model. The results have indicated that the extent of the dielectric friction effect dependent on the ET distance or the dipole change between the reactant and product.

Atomistic empirical pseudopotential theory is used to develop potentials for Ga, ln, As, and Sb atoms, together with the atomistic elasticity theory, through a valence force field approach, to calculate the evolution of the valence and conduction band edges of the quaternary Ga(sub 1-y)ln(sub y)As(sub x)Sb(sub 1-x) alloys grown lattice matched to GaSb and lnAs was applied. The results were compared with the results of the standard interpolative schemes widely employed by the device engineers to design devices and predict performances.

The structure of the Ir(super I) complex [Ir2(mu-OPy)2(CO)4] is fully characterized in its head-to-head configuration as a 'dimer of dimers' in which two binuclear complexes are connected by means of a weak, but unsupported, iridium-iridium interaction. The complex can be oxidized by diiodine to give iridium chains with highly selective configurations.

The rotation barriers in the group IVB ethane congeners H3X-YH3 (X, Y = C, Si, Ge, Sn, Pb) are systematically studied and deciphered using the ab initio valence bond theory in terms of the steric strain and hyperconjugation effect. The results obtained show that in all cases the rotation barriers are dominated by the steric repulsion whereas the hyperconjugative interaction between the X-H bond orbitals and the vicinal Y-H antibond orbitals plays a secondary role.

The results of ab initio valance bond calculations for S2N2 and S(sub 4)(super 2+) are reported using Dunning's D95 full double-epsilon basis set. The results suggest that the important Lewis structure for S2N2 is nitrogen singlet diradical structure (I), while for S(sub 4)(super 2+) is the two singlet diradical structures (XI and XII).

The visible/near-infrared (vis/NIR) spectra of four bis(triarylamine) radical cation mixed valence systems with varying bridge units in the framework of the generalized Mulliken-Hush theory are analyzed. A three level model is applied by using computational AM1-CI derived, experimental transition moments and energies to obtain electronic coupling matrix elements.

The reaction of Cu(I) with 2-pyridylacrylic acid (2-HPYA) is studied, which affords an unusual mixed-valence Cu(I)-Cu(III) 3-dimensional (3-D) framework. The results provide encouragement that the use of ligands combining carboxylate and pyridyl groups as building blocks in coordination polymers may provide access to a novel range of extended structures.

The synthesis and characterization of YBaFe(sub)2O(sub)5 is presented. It belongs to the family of double-cell perovskites RBaFe(sub)2O(sub)5, where R denotes a trivalent rare-earth ion. YBaFe(sub)2O(sub)5 possesses a narrowest range of phase stability and with decrease in temperature it exhibits a succession of class-III, II, and I mixed valence phases.

Infrared spectroelectrochemistry of the oxidation states of the hexaruthenium clusters, with pyrazine-d(sub)4 as bridging ligand, shows oxidation-dependent spectral changes. Further, a symmetric vibrational mode of pyrazine is seen for four pyrazine-bridged hexaruthenium mixed-valence complexes exhibiting electronic coupling between clusters.

The valence band dispersions for Bi(sub 2)Se(sub 3) are determined using angle resolved photoelectron spectroscopy (ARPES). The experimentally determined band dispersions are compared with theoretical band structure calculations and their results show a very good agreement between them in the ARPES spectra.

The spontaneous emission rate of semiconductors displays saturation at high carrier injection densities due to the filling of the conduction and valence bands. A simple analytic theory is developed that accounts for this saturation and can describe adequately the recombination kinetics of highly excited semiconductor quantum wells.

The full band calculation of the doping-induced energy shifts of the conduction-band minimum and the valence-band maximum for n- and p-type GaN and AlN is presented. The optical and reduced band-gap energies are presented as functions of the ionized impurity concentration in the heavily doped regime.

An overview of the possible decay channels and approximate energetics, using a valence-bond derived analysis to rationalize the structural details of the paths is presented. A valence-bond analysis shows that the ground state of cytosine has three localized double bonds.

The authors discuss the study on the mixed-valence compounds which contain transition metals. The topics of interest include the investigation of the charge-transfer excitation created mixed-valence molecules carried out via the transient near-infrared spectroscopy application.

Byline: Thorstein Thorsteinsson (1), David L. Cooper (2) Abstract: The CASVB approach is a recent development in modern valence bond theory which aims to provide easily visualized, highly accurate representations of very general types of CASSCF wavefunctions. Fully variational optimization may also be performed for quite general types of modern valence bond wavefunction. Numerous definitions of nonorthogonal weights are used to investigate the role of contributions from various types of 'ionic' configurations, taking hexatriene and [N.sub.2]S.sub.2 as illustrative examples. Author Affiliation: (1) Department of Chemistry, Chemistry Laboratory IV, Universitetsparken 5, 2100, Copenhagen A, Denmark (2) Department of Chemistry, University of Liverpool, P.O. Box 147, Liverpool, L69 7ZD, UK Article History: Registration Date: 29/09/2004

The substitution of bidentate anionic groups O2P(OH)2- of gamma-Zr(PO4)-O2P(OH)2*2H2O with couples of monodentate Cl--dimethyl sulfoxide ligands resulted in a new layered compound Zr-(PO4)Cl(CH3)2SO. The resulting compound's high reactivity makes it an ideal precursor for the preparation of new layered derivatives of general formula Zr(PO4)LL'. It can also be considered as an inorganic exchanger of monovalent anions.

Sr2CuGaO3S, a new gallium oxysulfide, was prepared by heating a pellet of stoichiometric amounts of SrS, Cu2O, Sr3Ga2O6, and Ga2O3 locked in an evacuated quartz tube at 950 degrees for 12 h. It crystallizes in a new layered structure of anti-PbO type Cu2S2 sheets alternating with gallium perovskite oxide layers. The Ga and O of the compound form a square pyramidal GaO3 layer, making it the first example of Ga with such coordination configuration in an extended structure.

Ab initio calculation shows hypervalent molecules such as SiF5-, PCl5, SF6 and XeF4 to obey the octet rule, which contrasts with Lewis definition of hypervalent compounds. The hypervalent concept finds no application in discussing similarities between BF3 and PF5, and CF4 and SF6, while such similarities can be discussed on the basis of Lewis octet rule. A correlated duodect rule helps analyze the similarities between the elements of third and fourth periods.

CpCr(NO)(ligand)(2) compounds with sigma-donor ligands are stable as 17-valence-electron cations, whereas 18-valence-electron-neutral stable compounds are associated with pi-acid ligands. Compound stability is related to the nature of the ligands associated with odd-electron species. Oxidation increases the substitutional lability in 18-electron complexes.

Analysis of a novel diruthenium complex, synthesized by aerobic oxidative dehydrogenation of trans(Ru(cyclam)Cl2)Cl (cyclam = 1,4,8, 11-tetraazacyclotetradecane) confirms it as the ruthenium analogue of a newly established diiron complex. The (Ru2+, Ru3+) mixed-valence species (Ru2 (C20H36N8)Cl4)+ is the complex isolated following aerobic oxidation of ruthenium(III) cyclam.

Resonance Raman investigations in the extended near infrared region provides an experimental validation of a three-site mixing process for valence delocalized in the Creutz-Taube ion, (NH3)5Ru(pyrazine)Ru(NH3)(sub 5)(super 5+). Elaborate, direct bridge orbital participation is involved. An antisymmetric metal-ligand structuring motion facilitates vibrational coupling of zeroth-order station.

Valence-bond theory regarding bond angles, bond lengths, resonance of molecules among alternative valence bond structures, variation in valence by formal transfer of electrons between atoms and other facts of molecular structure were used to reexamine the molecular structure of Ti8C12+ and M8C12+. Previous research had suggested a pentagonal dodecahedral structure for Ti8C12+. This has been disproved, and even the structure of M8C12+ differs from that suggested by previous research.