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Post-translational protein modification by ubiquitin (Ub) and ubiquitin-like (Ubl) proteins such as small ubiquitin-like modifier (SUMO) regulates processes including protein homeostasis, the DNA damage response, and the cell cycle. Proliferating cell nuclear antigen (PCNA) is modified by Ub or poly-Ub at lysine (Lys)164 after DNA damage to recruit repair factors. Yeast PCNA is modified by SUMO on Lys164 and Lys127 during S-phase to recruit the anti-recombinogenic helicase Srs2. Lys164 modification requires specialized E2/E3 enzyme pairs for SUMO or Ub conjugation. For SUMO, Lys164 modification is strictly dependent on the E3 ligase Siz1, suggesting the E3 alters E2 specificity to promote Lys164 modification. The structural basis for substrate interactions in activated E3/E2Ub/Ubl complexes remains unclear. Here we report an engineered E2 protein and cross-linking strategies that trap an E3/E2Ubl/substrate complex for structure determination, illustrating how an E3 can bypass E2 specificity to force-feed a substrate lysine into the E2 active site., Author(s): Frederick C. Streich Jr [1]; Christopher D. Lima (corresponding author) [1, 2] Ub and Ubl proteins are conjugated to substrate proteins by dedicated three-enzyme cascades involving E1 activating enzymes, [...]

Light-harvesting complex 1 (LH1) and the reaction centre (RC) form a membrane-protein supercomplex that performs the primary reactions of photosynthesis in purple photosynthetic bacteria. The structure of the LH1-RC complex can provide information on the arrangement of protein subunits and cofactors; however, so far it has been resolved only at a relatively low resolution. Here we report the crystal structure of the calcium-ion-bound LH1-RC supercomplex of Thermochromatium tepidum at a resolution of 1.9 Å. This atomic-resolution structure revealed several new features about the organization of protein subunits and cofactors. We describe the loop regions of RC in their intact states, the interaction of these loop regions with the LH1 subunits, the exchange route for the bound quinone Q.sub.B with free quinone molecules, the transport of free quinones between the inside and outside of the LH1 ring structure, and the detailed calcium-ion-binding environment. This structure provides a solid basis for the detailed examination of the light reactions that occur during bacterial photosynthesis.The structure of the Thermochromatium tepidum calcium-ion-bound light-harvesting-reaction centre (LH1-RC) supercomplex, which performs the primary reactions of photosynthesis in purple photosynthetic bacteria, is resolved to the atomic level., Author(s): Long-Jiang Yu [sup.1] , Michihiro Suga [sup.1] , Zheng-Yu Wang-Otomo [sup.2] , Jian-Ren Shen [sup.1] Author Affiliations:(1) Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, [...]

Each issue of Gold Bulletin contains key highlights from the research and patent literature. Authors who publish high-quality work in other journals are invited to send a copy of their [...]

Asymmetrical flow field-flow fractionation (AF4) coupled with UV-vis spectrophotometry, multiangle light scattering (MAILS), and dynamic light scattering (DLS) detection was used to analyze dispersions of DNA/ rhodamine B labeled chitosan (Ch-rho) complexes frequently used as gene delivery vectors. The method yielded, in a single experiment, important characteristics of the complexes, such as their hydrodynamic radius, size distribution, conformation, composition, and the amount of free Ch-rho in the dispersions. Samples for analysis were obtained by varying experimental parameters known to influence the transfection efficiency of DNA/chitosan complexes, including the DNA concentration at mixing (82-164 [micro]g/mL), the ratio of chitosan amino groups to DNA phosphate groups (3 [less than or equal to] N/P ratio [less than or equal to] 15), the chitosan molecular weight (10-76 kDa), and its degree of deacetylation. In all preparations, DNA/Ch-rho complexes had hydrodynamic radii ranging from 15 to 160 nm. Both the DNA concentration and the Ch-rho molecular weight influence the size distribution of the complexes: a greater fraction of large particles was detected in dispersions prepared with the most concentrated DNA solution or the Ch-rho of highest molar mass. All dispersions contained free Ch-rho in solution. The free Ch-rho content ranged from 53 to 92% of the total Ch-rho concentration in dispersions prepared with N/P ratios from 3 to 15, respectively, implying that the N/P ratio of the complexes ranged from 1.3 to 1.6 in all samples. The accuracy of the free Ch-rho determination by AF4/UV-vis/MALS+DLS was confirmed by an independent method involving (1) ultracentrifugation of the dispersions prepared with unlabeled chitosan and (2) analysis of the supernatant by the Orange II dye depletion method. This study demonstrates the ability of AF4/UV-vis/MALS+DLS to provide a complete physicochemical characterization of DNA/polycation complexes used in nonviral gene delivery. 10.1021/ac100711j

The interaction between an intact protein and two lipophilic ions at an oil--water interface has been investigated using cyclic voltammetry, impedance based techniques and a newly developed method in which the biphasic oil water system is analyzed by biphasic electrospray ionization mass spectrometry (BESI-MS), using a dual-channel electrospray emitter. It is found that the protein forms interfacial complexes with the lipophilic ions and that it specifically requires the presence of the oil--water interface to be formed under the experimental conditions. Furthermore, impedance based techniques and BESI-MS with a common ion to polarize the interface indicated that the Galvani potential difference across the oil--water interface significantly influences the interfacial complexation degree. The ability to investigate protein--ligand complexes formed at polarized liquid--liquid interfaces is thus a new analytical method for assessing potential dependent interfacial complexafion using a structure elucidating detection principle. 10.1021/ac101528r

The nonheme di-iron oxygenase, AurF, converts p-aminobenzoate (Ar-N[H.sub.2], where Ar = 4-carboxyphenyl) to p-nitrobenzoate (Ar-N[O.sub.2]) in the biosynthesis of the antibiotic, aureothin, by Streptomyces thioluteus. It has been reported that this net six-electron oxidation proceeds in three consecutive, two-electron steps, through p-hydroxylaminobenzoate (Ar-NHOH) and p-nitrosobenzoate (Ar-NO) intermediates, with each step requiring one equivalent of [O.sub.2] and two exogenous reducing equivalents. We recently demonstrated that a peroxodiiron(III/III) complex (peroxo-[Fe.sup.2.sup.III/III]-AurF) formed by addition of [O.sub.2] to the diiron(II/II) enzyme ([Fe.sub.2.sup.II/II]-AurF) effects the initial oxidation of Ar-N[H.sub.2], generating a [mu]-(oxo)diiron (III/III) form of the enzyme ([mu]-oxo-[Fe.sub.2.sup.III/III]-AurF) and (presumably) Ar-NHOH. Here we show that peroxo-[Fe.sub.2.sup.III/III]-AurF also oxidizes Ar-NHOH. Unexpectedly, this reaction proceeds through to the Ar-N[O.sub.2] final product, a four-electron oxidation, and produces [Fe.sub.2.sup.II/II]-AurF, with which [O.sub.2] can combine to regenerate peroxo-[Fe.sub.2.sup.III/III]-AurF. Thus, conversion of Ar-NHOH to Ar-N[O.sub.2] requires only a single equivalent of [O.sub.2] and (starting from [Fe.sub.2.sup.II/II]-AurF or peroxo-[Fe.sub.2.sup.III/III]-AurF) is fully catalytic in the absence of exogenous reducing equivalents, by contrast to the published stoichiometry. This novel type of four-electron N-oxidation is likely also to occur in the reaction sequences of nitro-installing di-iron amine oxygenases in the biosyntheses of other natural products. doi/ 10.1073/pnas.1002785107

Here we report the use of capillary isoelectric focusing under native conditions for the separation of protein complex isoforms and subcomplexes. Using biologically relevant HIS-tsg and FLAG-tag purified protein complexes, we demonstrate the separations of protein complex isoforms of the mammalian target of rapamycin complex (mTORC1 and 2) and the subcomplexes and different phosphorylation states of the Dam1 complex. The high efficiency capillary isoelectric focusing separation allowed for resolution of protein complexes and subcomplexes similar in size and biochemical composition. By performing separations with native buffers and reduced temperature (15[degrees]C) we were able to maintain the complex integrity of the more thermolabile mTORC2 during isoelectric focusing and detection ( 10.1021/ac101235k

Crystal engineering of nanoporous structures has not yet exploited the heme motif so widely found in proteins. Here, we report that a derivative of iron phthalocyanine, a close analog of heme, forms millimeter-scale molecular crystals that contain large interconnected voids (8 cubic nanometers), defined by a cubic assembly of six phthalocyanines. Rapid Ligand exchange is achieved within these phthalocyanine nanoporous crystals by single-crystal-to-single-crystal (SCSC) transformations. Differentiation of the binding sites, similar to that which occurs in hemoproteins, is achieved so that monodentate ligands add preferentially to the axial binding site within the cubic assembly, whereas bidentate ligands selectively bind to the opposite axial site to link the cubic assemblies. These bidentate ligands act as molecular wall ties to prevent the collapse of the molecular crystal during the removal of solvent. The resulting crystals possess high surface areas (850 to 1000 square meters per gram) and bind N2 at the equivalent of the heme distal site through a SCSC process characterized by x-ray crystallography. 10.1126/science.1184228

The density functional theory (DFT) method has been employed to unravel mechanistic intricacies of the 1,4- polymerization of 1,3-butadiene mediated by the [[([η.sup.3]-R[C.sub.3][H.sub.4]) [Fe.sup.II]([C.sub.15][H.sub.11][N.sub.3])([η.sup.2]-[C.sub.4] [H.sub.6])].sup.+] terpyridine--iron(II) active catalyst species. The π-allyl-insertion mechanism is operative for chain growth, whilst the alternative σ-allyl- insertion mechanism has been explicitly demonstrated as being inoperable. This study elucidates the mechanism of cis--trans regulation and unveils the factors that govern the observed high trans-1,4 stereoselectivity, in particular, the discriminative role of allylic isomerization. An atactic trans-1,4-polydiene is expected from polymerization of a terminally monosubstituted butadiene, the experimental results of which have not been reported thus far. Key words: 1,3-diene polymerization, reaction mechanisms, structure-reactivity relationships, iron complexes, density functional calculations. La methode DFT a ete employee afin d'eclaircir les subtilites de la 1,4-polymerisation du 1,3-butadiene assistee par les especes terpyridine-fer(II) [([([η.sup.3]-R[C.sub.3][H.sub.4]) [Fe.sup.II]([C.sub.15][H.sub.11][N.sub.3])([η.sup.2]-[C.sub.4] [H.sub.6])].sup.+]) catalytiquement actives. Le mecanisme selon l'insertion π-allylique se deroule pour la croissance de chaine tandis que le mecanisme alternatif selon l'insertion s-allylique a ete explicitement demontre comme inoperable. Cette etude elucide le mecanisme de la regulation cis-trans et devoile les facteurs gouvernant la haute stereoselectivite trans-1,4 observee, en particulier le role discriminatoire de l'isomerisation allylique. Un trans-1,4-polydiene atactique est attendu a partir de la polymerisation d'un butadiene monosubstitue en position terminale. Ces resultats experimentaux n'ont pas ete reportes jusque-la. Mots-cles : polymerisation du 1,3-diene, mecanismes reactionnels, relations structure-reactivite, complexes de fer, calculs de la fonctionnelle de la densite. [Traduit par la Redaction], Introduction The metal-catalyzed polymerization of 1,3-dienes is a key process in the chemical industry and as such has triggered considerable research efforts in both academia and industry. (1-5) Structurally defined [...]

Quantum chemical calculations using BP86 with TZ2P basis sets were carried out to elucidate the structures and the bond-bond dissociation energies of the donor-acceptor complexes [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] with X = H, F, Cl, Br, I; E = B, Al, Ga, In, Tl; and M = Ni, Pd, Pt. The nature of the metal-ligand bond was investigated with an energy decomposition analysis. The geometry optimizations gave for most compounds T-shaped structures with nearly linear P-M-P angles where the [EX.sub.3] ligand has either a staggered or eclipsed conformation with respect to the PMP plane. The energy differences between the conformations are very small which means that there is nearly free rotation about the [M-EX.sub.3] axis. The equilibrium structures of eight nickel compounds have a distorted geometry where one E-X bond is engaged in attractive interactions with the metal atom which yields a distorted square-planar arrangement of the metal atom. The complex [[(P[Me.sub.3]).sub.2]Ni-Tl[I.sub.3]] exhibits two attractive interactions between Tl-I bonds and the metal which features a five-coordinated metal atom. The calculated bond dissociation energies show that the boron complexes exhibit a different trend for the [D.sub.e] values than the heavier group-13 homologues. The results for the Pd and Pt complexes suggest that the [[(P[Me.sub.3]).sub.2][M-BX.sub.3]] bond strength increases with F < Cl < Br < I < H which means that the [BH.sub.3] ligands are the most strongly bonded Lewis acids and [BF.sub.3] is the most weakly bonded species . The trend for the heavier group-13 complexes [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] where E = Al, Ga, In, Tl follows the opposite order F > Cl > Br > I > H. The energy decomposition analysis of the [M-EX.sub.3] bonds indicates a substantial π contribution of between 12.7% and 30.3% to the total orbital interactions. There is no direct correlation between the strength of the orbital interactions or any of the other energy terms Δ[E.sub.elstat] or Δ[E.sub.Pauli] which correlates with the total interaction energy. The bond dissociation energy of the [EX.sub.3] ligands after breaking the [M-EX.sub.3] bonds is quite large. It is shown that the intrinsic strength of the [M-EX.sub.3] bonds is much larger than the BDEs and that the trends of Δ[E.sub.int] and [D.sub.e] are not always the same. The [EX.sub.3] ligands in [[(P[Me.sub.3]).sub.2][M-BX.sub.3]] always carry a large negative charge. Key words: density functional calculations, bonding analysis, Lewis acids, transition metal complexes, reversed DCD model. On a effectue des calculs de mecanique quantique BP86 a l'aide d'ensembles de base TZ2P dans le but d'elucider les structures et les energies de dissociation de liaison des complexes donneur-accepteur [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] dans lesquels X = H, F, Cl, Br, et I; E = B, Al, et Ga, In, Tl; et M = Ni, Pd, et Pt. On a etudie la nature de la liaison metal-ligand par le biais d'une analyse de l'energie de decomposition. Les optimisations de la geometrie conduisent, pour la plupart des composes, a des structures en forme de T avec des angles P-M-P pratiquement lineaires, dans lesquels le ligand [EX.sub.3] se trouve dans une conformation decalee ou eclipsee par rapport au plan PMP. Les differences d'energie entre les conformations sont tres faibles, ce qui implique qu'il existe une rotation pratiquement libre autour de l'axe [M-EX.sub.3]. Les structures a l'equilibre dans les neuf composes du nickel comportent toutes une geometrie deformee dans laquelle une liaison E-X est engagee dans des interactions attractives avec l'atome metallique ce qui conduit a un arrangement plan carre deforme de l'atome metallique. Le complexe [[(P[Me.sub.3]).sub.2]Ni-Tl[I.sub.3]] presente meme deux interactions attractives entre les liaisons Tl-I et le metal qui comporte un atome de metal pentacoordonne. Les energies de dissociation de liaison calculees montrent que les complexes de bore presentent une tendance differente pour les valeurs [D.sub.e] que les homologues plus lourds du groupe 13. Les resultats pour les complexes du Pd et du Pt suggerent que la force de la liaison [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] augmente avec F < Cl < Br < I < H, ce qui signifie que les ligands [BH.sub.3] sont les acides de Lewis les plus fortement lies et que les especes [BF.sub.3] participent aux liaisons les plus faibles. La tendance pour les complexes plus lourds du groupe 13 [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] dans lesquels E = Al, Ga, In et Tl conduit a l'ordre inverse F > Cl > Br > I > H. L'analyse de l'energie de decomposition des liaisons [M-EX.sub.3] met en evidence la presence d'une contribution π importante, allant de 12,7 % a 30,3 % des interactions or bitalaires totales. Il n'existe aucune correlation directe entre la force des interactions orbitalaires ou l'un des autres termes d'energie, tel Δ[E.sub.elstat] ou Δ[E.sub.Pauli] et l'energie totale d'interaction. L'energie de dissociation de la liaison des ligands [EX.sub.3] apres le bris des liaisons [M-EX.sub.3] est tres elevee. On a demontre que la force intrinseque des liaisons [M-EX.sub.3] est beaucoup plus elevee que les BDE et que les tendances des Δ[E.sub.int] et [D.sub.e] ne sont pas toujours les memes. Les ligands [EX.sub.3] dans les complexes [[(P[Me.sub.3]).sub.2][M-EX.sub.3]] portent toujours une forte charge negative. Mots-cles : calculs de la fonctionnellle de la densite, analyse de liaison, acides de Lewis, complexes de metaux de transition, modele DCD inverse. [Traduit par la Redaction], Introduction The chemical bonds in donor-acceptor complexes of transition metals with main-group ligands are usually described using the Dewar-Chatt-Duncanson (DCD) model (1) where the ligand, being a Lewis base, serves [...]

The quantitative study of noncovalent complexes by electrospray mass spectrometry requires the determination of the relative response of each species. The method proposed here to determine the electrospray response factors is based on the use of (1) an internal standard and (2) the mass balance equation applied to one binding partner M, for which different complexes [M.sub.x][L.sub.y] are detected in the electrospray mass spectra. A set of experiments providing various ratios between the complexes (e.g., different ligand concentrations in a titration experiment or different time points in a kinetics experiment) is used to generate a set of independent linear equations that can be solved using simple matrix algebra to find the response factors of each MxLy complex relative to that of the internal standard. The response factors can then be used to determine equilibrium dissociation constants or for the quantitative monitoring of reaction kinetics. The first is illustrated with a study of DNA-ligand complexes, where we show that neither minor groove binding nor intercalation dramatically affects the DNA response factor. The second is illustrated with a study of the association kinetics of the telomeric G-quadruplex d~AGGG)3 with its complementary strand, where the response factors allow correcting for the relative response of the quadrnplex and the long duplex and obtaining reproducible association rate constants independently of the source tuning potentials.

In the framework of nuclear waste disposal, it is very important to well understand the behavior of actinides in the presence of the common environmental inorganic ligands such as sulfate and chloride. In rids work, the An[O.sub.2]S[O.sub.4.sup.-] and An[O.sub.2]Cl 1-1 complexes have been evidenced by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICPMS) in perchlorate/chloride and in perchlorate/sulfate media for An = Np and Pu. Their binding constants have been measured: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. These results are consistent with published values for Np(V). They confirm the expected analogy between Np(V) and Pu(V) for the weak bonding with chloride ligand, [log.sub.10] [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], attributed to mainly electrostatic interactions. Conversely, a slight shift is observed for the bonding with sulfate ligand, [log.sub.10] [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], indicating that some covalency might stabilize the sulfate complexes.

Designed experiments were conducted in this paper to study the effect of Au/Ni/Cu or Cu substrate pad metallization on the electromigration reliability of 96.5Sn--3Ag--0.5Cu flip-chip solder joints with Ti/Ni(V)/Cu under bump metallurgy (UBM) under a current stressing condition with an average current density of around 5 kA/[cm.sup.2] at an ambient temperature of 150[degrees]C. Cross-sectional observations on current-stressed solder joints indicate that although Cu metallization results in severe voiding compared with Au/Ni/Cu metallization on the substrate side of the solder joint, the dominant failure has been identified as UBM consumption, and test vehicles with Cu metallization exhibit better electromigration reliability than those with Au/Ni/Cu metallization. The stronger durability against current stressing for test vehicles with Cu metallization may attribute to the lower UBM consumption rate due to the continuous Cu diffusion toward UBM as a result of the concentration gradient. The consumption of UBM is faster for test vehicles with Au/Ni/Cu metallization because Cu diffusion from the substrate pad is retarded by the Ni barrier. [DOI: 10.1115/1.3103945] Keywords: electromigration, reliability, flip-chip, solder joint, substrate pad metallization

A novel in-line surface-induced dissociation (SID) device was designed and implemented in a commercial QTOF instrument (Waters/Micromass QTOF II). This new setup allows efficient SID for a broad range of molecules. It also allows direct comparison with conventional collision-induced dissociation (CID) on the same instrument, taking advantage of the characteristics of QTOF instrumentation, including extended mass range, improved sensitivity, and better resolution compared with quadrupole analyzers and ion traps. Various peptides and a noncovalent protein complex have been electrosprayed and analyzed with the new SID setup. Here we present SID of leucine enkephalin, fibrinopeptide A, melittin, insulin chain-B, and a noncovalent protein complex from wheat, heat shock protein 16.9. The SID spectra were also compared to CID spectra. With the SID setup installed, ion transmission proved to be efficient. SID fragmentation patterns of peptides are, in general, similar to CID, with differences in the relative intensities of some peaks such as immonium ions, backbone cleavage b- versus y-type ions, and y- versus y-N[H.sub.3] ions, suggesting enhanced accessibility to high-energy/secondary fragmentation channels with SID. Furthermore, these results demonstrate that the in-line SID setup is a valid substitute for CID, with potential advantages for activation of singly/multiply charged peptides and larger species such as noncovalent protein complexes.

The planar tetra- (ptC), penta- (ppC) and hexacoordination carbon (phC) and hexacoordinate carbon (phC) are studied by exploring the whole family of carbon-boron mixed clusters and their anions. The studies have shown that the planar tetra-, penta- and hexacoordinate boron are the prevalent structural motifs in low-lying isomers of the carbon-boron clusters and the stability of the ptC and ppC units is reinforced over the boron-centered isomers by attaching proper hydrocarbon unit to form the hyparenes.

Douglas-Kroll-Hess density functional calculations are performed for 34 tin compounds of which molecular structures and [sup.119.Sn] Mossabauer spectroscopy parameters are experimentally known. The result shows that the Douglas-Kroll-Hess approach provides reliable electric field gradients in the case of closed shell metal compounds.

The characterization of three MH-C[H.sub.2]C[H.sub.3], M[H.sub.2]-(C[H.sub.2].sub.2) and M[H.sub.3]-CH=C[H.sub.2] complexes are presented. The density functional theory calculations are used for this purpose.

Diffusion coefficients of metal complexes inside silica-surfactant nanochannels formed within porous alumina membrane are described. The result show that diffusion coefficients of charged metal complexes are of smaller magnitude due to the electrostatic interaction with ionic interface and in neutral ferrocene are influenced by the hydrophobicity rather than the molecular size.

The comparison of the emission spectra of five 1:1 complexes of 2-pyridone (2PY) with formic acid (FA), acetic acid (AA), propanoic acid (PA), formamide (FM) and acetamide (AM) is presented. Findings reveal that the methyl group belonging to the AA and AM moieties is responsible for the acceleration of the vibrational energy redistribution (IVR) in the 2PY moiety.

A method is described for the preparation of a variety of cyclobutanes via 4-exo cyclization of radicals. Efficient conditions are established for the catalytic preparation of a number of substituted cyclobutanes by choosing appropriate titanocene complexes.

The effects of 10 paramagnetic metal complexes on [F.sup.-] ion [super 19]F NMR transverse relaxation rates are studied in aqueous solutions as a function of temperature. The results have shown that [F.sup.-] [super 19]F NMR relaxation is used for predicting the reactivities of other [Fe.sup.III] complexes toward reduction by [O.sub.2.sup.-], which is a key step in the biological production of reactive oxygen species.

Density functional theory (DFT) is used for assessing the [pi]-acidity and [pi]-basicity of metal-organic trimetallic macromolecular complexes of the type [[M([mu]-L)].sub.3], where M = Cu, Ag, or Au and L = carbeniate, imidazolate, pyridiniate, pyrazolate or triazolate. The results have indicated that the metal-organic macromolecules have shown superior [pi]-acidity and -basicity when compared to their organic counterparts.

The mechanisms of the hydrosilylation reactions of unsaturated compounds with the tungsten complexes are examined by using the density functional theory method. The results have shown that the hydrosilylation of acetone has proceeded through a metal hydride migration, while the hydrosilylation of nitrile has occurred through a silyl migration mechanism.

A unified strategy is described for the high-throughput synthesis of multigram quantities of [[eta].sup.3]-oxopyranyl- and [[eta].sup.3]-oxopyridinylmolybdenum complexes. This strategy has used the oxa- and aza-Achmatowicz reaction for preparing the organometallic enantiomeric scaffolds, in both racemic and high enantiopurity versions.

The extremely robust and water-stable tetranuclear complex [Ti.sub.4][([micro]-BINOLato).sub.6][([[micro].sub.3]-OH).sub.4] has catalyzed the direct aldol addition with high degrees of regioselectivity at the sterically more encumbered [alpha]-side of unsymmetrical ketones. No clusters are seen in crystalline form with mixed configuration of the incorporation BINOLs.

A soluble molecular analogue of photoresponsive Co/Fe Prussian blues is prepared and characterized. The structures, spectroscopic properties and magnetic behavior of an octanuclear {[Fe.sub.4.sup.III][Co.sub.4.sup.III]} complex that has exhibited reversible intramolecular charge transfer as a function of temperature and light irradiation are described.

The room temperature intercalation of [Cr.sub.2][Ti.sub.3][Se.sub.8] with butyl lithium has yielded a phase mixture of the starting material and of the new trigonal phase with composition [Li.sub.0.4][Cr.sub.0.5][Ti.sub.0.75][Se.sub.2]. The results have shown the role of the charge transfer between the constituents as a function of the Li concentration and its impact on the exchange coupling.

Mononuclear ruthenium vinyl complexes L-{Ru}-CH[double bond]CH-R is described where the phosphine ligands, the coordination number at the metal and substituent are varied. The vinyl ligands have contributed to the anodic oxidation processes, rendering them a class of truly 'non-innocent' ligands in organometallic ruthenium chemistry.

The studies probing the energy-transfer processes between water-soluble core/shell CdSe/ZnS quantum dots and many transition metal complexes are presented. The results have shown that the donor-acceptor interaction in solution is dominated by preassociation between the anionic CdSe/ZnS QDs and the cationic Cr(III) complexes prior to optical excitation.

The spin transition in the reactions of the derivatives of imidazo[1,2-a]pyrazin-3(7H)-one with a triplet molecular oxygen is examined by the geometry optimization and the electronic matrix elements for spin-orbit coupling (SOC) is evaluated by using the full Pauli-Breit SOC operator. An optimal state is present for the suppression of SOC in the charge-transfer-induced luminescence (CTIL) for the peroxide, which is related with the ability of a substituent to donate an electron.

The charge-transfer-to-solvent (CTTS)-driven femtosecond-scale dissolution dynamics for [I.sup.-][([H.sub.2]O).sub.n=2-5] clusters is analyzed by using excited state (ES) ab initio molecular dynamics (AIMD) simulations. The CTTS-driven dissolution dynamics is used for designing the receptors that are able to bind and release ions in host-guest chemistry.

The X-ray crystal structure of the I100W variant of ToMOH enzyme and the reaction between diiron(II) and dioxygen which yields a diiron(III) intermediate is described. The intermediate subsequently abstracts an electron from W100 to form a chromophoric mixed-valent diiron(III,IV)-W* species.

The linked equilibrium in G-quadruplex (G4 DNA) specific ligand complexes which play significant role as anticancer molecules of telomerase inhibitors is described.

The syntheses and characterizations of a series of novel fluorotitanophosphates [(N[H.sub.4]).sub.x][K.sub.4-x][[Ti.sub.2]P[O.sub.4][F.sub.9]] (x = 0, 0.70, 1.00, 1.25) are described. The partial substitution of potassium by ammonium has shown that the structure has converted to a more-symmetric version, while maintaining all of the topological features.

New tertiary phosphines [Ph.sub.2]PCH(Ar)C[H.sub.2]CHO, bearing an aliphatic aldehyde group in the side chain, are prepared by hydrophosphination of the C[double bond]C bond of the corresponding cinnamaldehyde in a 1:1 reaction with [Ph.sub.2]PH at room temperature in the absence of solvent. The analysis of the phosphine complex has shown that the S,S- and R,R-enantiomers are favored.

Catalytically active palladium(II) complexes are synthesized by oxidizing the phosphorous centers with a proper amount of water from the 1:1 and 1:2 reactions of aminobis(phosphonite) and palladium precursor, where the thioether-phosphonate moiety has formed a metallacycle containing a metal-phosphorous [sigma] bond. These palladium complexes are shown to be very good catalysts for the Suzuki-Miyaura and Mizoroki-Heck cross-coupling and amination reactions with very good turnover numbers.

Uranyl complex dissolved in room-temperature ionic liquids has diagnostic absorption and emission spectra that has allowed the identification of the symmetry and geometry of the complex. The uranyl complexes are examined in imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids.

The synthesis and characterization of neutral heteroleptic molecular iridium(III) complexes with (2,4-difluoro)phenylpyridine and different pyridine-1,2,4-triazole ligands are described. The studies have shown high external quantum efficiencies and color points better than the standard for blue iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,[C.sup.2]]picolinate.

Electron paramagnetic resonance (EPR) spectroscopy is used for studying the thermally induced spin transitions in a family of heterospin polymer chain complexes of [Cu.sup.2} hexafluoroacetylacetonate with two pyrazole-substituted nitronyl nitroxides. The studies have shown an efficient tool for characterizing the spin transitions and for understanding the temperature-dependent sign and value of the exchange interaction in strongly coupled spin triads.

The kinetics of disappearance of the superoxorhodium complex is determined in the presence of many oxidants in both air-free and air-saturated aqueous solutions. The differences in equilibrium constants are attributed to the lower reduction potential of the rhodium complex.

The iron(III) complexes of 1,4,8,11-tetraaza[14]annulenes are prepared as catalase mimics. A non-oxygen releasing pathway of hydrogen peroxide decomposition is disclosed besides oxygen production.

The synthesis and photophysical properties of anthraquinone-bridged mononuclear and dinuclear platinum(II) complexes are described. The results have shown that the restriction of the Pt-Pt distance flexibility in the rigid structure of this complex has prevented the increase of the Pt-Pt interaction at the excited state.

The synthesis, structure and properties of new yttrium dichloro, dialkyl and bis(triethylborohydride) complexes coordinated by N,N'-diisopropyl-N'-bis(trimethylsilyl)guanidinate ligand are described. This ligand has allowed the synthesis and isolation of new monomeric salt-free yttrium complexes.

The synthesis and characterization of a series of amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with hydrophilic poly(oxyethylene) heads and hydrophobic alkoxy tails are described. The studies have shown that the devices have exhibited very good organic field effect transistor (OFET) performance with the carrier mobility for holes in the direction of parallel to the aromatic phthalocyanine rings.

The high-yield synthesis of gold-tellurollate clusters [[Au.sub.8]([mu]-TeR).sub.8][[(PR'.sub.3]).sub.4]] (TeR = TePh, TeTol, [PR'.sub.3] = P[Ph.sub.3], P[Ph.sub.3]py) is described. The gold-tellurium complexes are novel due to their special structural features and luminescent behavior in solid state and in solution.

The reactions of the tungsten trisulfido complex of hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) [[Et.sub.4]N][Tp*W[S.sub.3]] with 3 equiv CuCl in CH[Cl.sub.3] has yielded a tetranuclear anionic cluster. The third order nonlinear optical (NLO) properties of these complexes are examined in solution under the femtosecond degenerate four-wave mixing method.