Synthesis and structures of cyclic gold complexes containing diphosphine ligands and luminescent properties of the high nuclearity species

A mixture of cyclic gold(I) complexes [Au(2)(μ-cis-dppen)(2)]X(2) (X = OTf 1, PF(6)3) and [Au(cis-dppen)(2)]X (X = OTf 2, PF(6)4) is obtained from the reaction of [Au(tht)(2)]X (tht = tetrahydrothiophene) with one equivalent of cis-dppen [dppen = 1,2-bis(diphenylphosphino)ethylene]. The analogous reaction with trans-dppen or dppa [dppa = bis(diphenylphosphino)acetylene] affords the cyclic trinuclear [Au(3)(μ-trans-dppen)(3)]X(3) (X = OTf 11, PF(6)12) and tetranuclear [Au(4)(μ-dppa)(4)]X(4) (X = OTf 13, PF(6)14, ClO(4)15) gold complexes, respectively. Recrystallization of 15 from CH(2)Cl(2)/MeOH yielded a crystal of the octanuclear gold cluster [Au(8)Cl(2)(μ-dppa)(4)](ClO(4))(2)16. Attempts to prepare dicationic binuclear gold(II) species from the reaction of a mixture of 3 and 4 with halogens gave a mixture of products, the components of which confirmed to be acyclic binuclear gold(I) [Au(2)X(2)(cis-dppen)] (X = I 5, Br 7) and cyclic mononuclear gold(III) [AuX(2)(cis-dppen)]PF(6) (X = I 6, Br 8) complexes. Complexes 11-14 reveal weak emission in butyronitrile glass at 77 K, but they are non-emissive at room temperature. Ab initio modelling was performed to determine the charge state of the gold atoms involved. Extensive structural comparisons were made to experimental data to benchmark these calculations and rationalize the conformations.     

Insight into the dinuclear {Fe(NO)2}10{Fe(NO)2}10 and mononuclear {Fe(NO)2}10 dinitrosyliron complexes

The reversible redox transformations [(NO)(2)Fe(S(t)Bu)(2)](-) ? [Fe(μ-S(t)Bu)(NO)(2)](2)(2-) ? [Fe(μ-S(t)Bu)(NO)(2)](2)(-) ? [Fe(μ-S(t)Bu)(NO)(2)](2) and [cation][(NO)(2)Fe(SEt)(2)] ? [cation](2)[(NO)(2)Fe(SEt)(2)] (cation = K(+)-18-crown-6 ether) are demonstrated. The countercation of the {Fe(NO)(2)}(9) dinitrosyliron complexes (DNICs) functions to control the formation of the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) dianionic reduced Roussin's red ester (RRE) [PPN](2)[Fe(μ-SR)(NO)(2)](2) or the {Fe(NO)(2)}(10) dianionic reduced monomeric DNIC [K(+)-18-crown-6 ether](2)[(NO)(2)Fe(SR)(2)] upon reduction of the {Fe(NO)(2)}(9) DNICs [cation][(NO)(2)Fe(SR)(2)] (cation = PPN(+), K(+)-18-crown-6 ether; R = alkyl). The binding preference of ligands [OPh](-)/[SR](-) toward the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) motif of dianionic reduced RRE follows the ligand-displacement series [SR](-) > [OPh](-). Compared to the Fe K-edge preedge energy falling within the range of 7113.6-7113.8 eV for the dinuclear {Fe(NO)(2)}(9){Fe(NO)(2)}(9) DNICs and 7113.4-7113.8 eV for the mononuclear {Fe(NO)(2)}(9) DNICs, the {Fe(NO)(2)}(10) dianionic reduced monomeric DNICs and the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) dianionic reduced RREs containing S/O/N-ligation modes display the characteristic preedge energy 7113.1-7113.3 eV, which may be adopted to probe the formation of the EPR-silent {Fe(NO)(2)}(10)-{Fe(NO)(2)}(10) dianionic reduced RREs and {Fe(NO)(2)}(10) dianionic reduced monomeric DNICs in biology. In addition to the characteristic Fe/S K-edge preedge energy, the IR ν(NO) spectra may also be adopted to characterize and discriminate [(NO)(2)Fe(μ-S(t)Bu)](2) [IR ν(NO) 1809 vw, 1778 s, 1753 s cm(-1) (KBr)], [Fe(μ-S(t)Bu)(NO)(2)](2)(-) [IR ν(NO) 1674 s, 1651 s cm(-1) (KBr)], [Fe(μ-S(t)Bu)(NO)(2)](2)(2-) [IR ν(NO) 1637 m, 1613 s, 1578 s, 1567 s cm(-1) (KBr)], and [K-18-crown-6 ether](2)[(NO)(2)Fe(SEt)(2)] [IR ν(NO) 1604 s, 1560 s cm(-1) (KBr)].     

Influence of High-energy electron-beam on photocatalytic activity of TiO2 films on carbon-fiber deposited by atomic layer deposition

High-energy electron-beam with energy of 1 MeV was used for modifying surface structure of TiO₂ thin films on carbon fiber prepared by using atomic layer deposition under atmospheric pressure. TiO₂ nanoparticles (∼20 nm) on carbon fiber underwent structural modification of the surface upon electron-beam treatment, resulting in enhanced photocatalytic activity. In contrast, a thicker film of TiO₂ did not show such changes in surface structure and photocatalytic activity by electron-beam treatment. We demonstrate that electron-beam can be used for modifying surface structure of photocatalysts consisting of nanoparticles for improvement of their activity.     

Genetic association of the EGR2 gene with bipolar disorder in Korea

The early growth response gene 2 (EGR2) is located at chromosome 10q21, one of the susceptibility loci in bipolar disorder (BD). EGR2 is involved in cognitive function, myelination, and signal transduction related to neuregulin-ErbB receptor, Bcl-2 family proteins, and brain-derived neurotrophic factor. This study investigated the genetic association of the EGR2 gene with BD and schizophrenia (SPR) in Korea. In 946 subjects (350 healthy controls, 352 patients with BD, and 244 with SPR), nine single nucleotide polymorphisms (SNPs) in the EGR2 gene region were genotyped. Five SNPs showed nominally significant allelic associations with BD (rs2295814, rs61865882, rs10995315, rs2297488, and rs2297489), and the positive associations of all except rs2297488 remained significant after multiple testing correction. Linkage disequilibrium structure analysis revealed two haplotype blocks. Among the common identified haplotypes (frequency > 5%), 'T-G-A-C-T (block 1)' and 'A-A-G-C (block 2)' haplotypes were over-represented, while 'C-G-G-T-T (block 1)' haplotype was under-represented in BD. In contrast, no significant associations were found with SPR. Although an extended analysis with a larger sample size or independent replication is required, these findings suggest a genetic association of EGR2 with BD. Combined with a plausible biological function of EGR2, the EGR2 gene is a possible susceptibility gene in BD.     

Borane-induced dehydration of silica and the ensuing water-catalyzed grafting of B(C6F5)3 to give a supported, single-site Lewis acid, ≡SiOB(C6F5)2

A supported, single-site Lewis acid, ≡SiOB(C(6)F(5))(2), was prepared by water-catalyzed grafting of B(C(6)F(5))(3) onto the surface of amorphous silica, and its subsequent use as a cocatalyst for heterogeneous olefin polymerization was explored. Although B(C(6)F(5))(3) has been reported to be unreactive toward silica in the absence of a Br?nsted base, we find that it can be grafted even at room temperature, albeit slowly. The mechanism was investigated by (1)H and (19)F NMR, in both the solution and solid states. In the presence of a trace amount of H(2)O, either added intentionally or formed in situ by borane-induced dehydration of silanol pairs, the adduct (C(6)F(5))(3)B·OH(2) hydrolyzes to afford C(6)F(5)H and (C(6)F(5))(2)BOH. The latter reacts with the surface hydroxyl groups of silica to yield ≡SiOB(C(6)F(5))(2) sites and regenerate H(2)O. When B(C(6)F(5))(3) is present in excess, the resulting grafted boranes appear to be completely dry, due to the eventual formation of [(C(6)F(5))(2)B](2)O. The immobilized, tri-coordinate Lewis acid sites were characterized by solid-state (11)B and (19)F NMR, IR, elemental analysis, and C(5)H(5)N-TPD. Their ability to activate two molecular C(2)H(4) polymerization catalysts, Cp(2)ZrMe(2) and an (α-iminocarboxamidato)nickel(II) complex, was explored.     

Study on a separation method of radionuclides (Ba, Sr) from LiCl salt wastes generated from the electroreduction process of spent nuclear fuel

In this paper, a separation method of radionuclides (Ba, Sr) from LiCl salt wastes generated from the electroreduction process of spent nuclear fuel was studied to recover pure LiCl salts and reduce radioactive wastes. The method consisted of chemical conversion process of BaCl₂ and SrCl₂ in LiCl molten salts by using lithium compounds and vacuum distillation process of LiCl salts. In the chemical conversion, BaCl₂ and SrCl₂ in LiCl molten salts were mainly converted into (Ba,Sr)CO₃ or (Ba,Sr)SO₄. Contents of Ba and Sr in LiCl salts recovered from the vacuum distillation process were equal to about 0.01 of initial concentrations of Ba and Sr in LiCl molten salts. These results will be utilized to recycle the LiCl salt wastes.     

Theoretical investigation on electron scattering by benzene in the intermediate-energy range

We present a theoretical investigation on electron scattering by benzene (C₆H₆) in the intermediate-energy range. Calculated elastic differential, integral, and momentum-transfer as well as total (elastic + inelastic) and total absorption cross sections are reported for impact energies ranging from 20 to 500 eV. A complex optical potential is used to represent the electron-molecule interaction dynamics. A theoretical method based on the single-center-expansion close-coupling framework and corrected by the Padé approximant [F.A. Gianturco, R.R. Lucchese, N. Sanna, J. Chem. Phys. 102 (1995) 5743] is used to solve the scattering equations. The comparison of our calculated results with the experimental and theoretical data available in the literature is encouraging.     

Side-chain tunability of furan-containing low-band-gap polymers provides control of structural order in efficient solar cells

The solution-processability of conjugated polymers in organic solvents has classically been achieved by modulating the size and branching of alkyl substituents appended to the backbone. However, these substituents impact structural order and charge transport properties in thin-film devices. As a result, a trade-off must be found between material solubility and insulating alkyl content. It was recently shown that the substitution of furan for thiophene in the backbone of the polymer PDPP2FT significantly improves polymer solubility, allowing for the use of shorter branched side chains while maintaining high device efficiency. In this report, we use PDPP2FT to demonstrate that linear alkyl side chains can be used to promote thin-film nanostructural order. In particular, linear side chains are shown to shorten π-π stacking distances between backbones and increase the correlation lengths of both π-π stacking and lamellar spacing, leading to a substantial increase in the efficiency of bulk heterojunction solar cells.