A long-range-corrected time-dependent density functional theory

We apply the long-range correction (LC) scheme for exchange functionals of density functional theory to time-dependent density functional theory (TDDFT) and examine its efficiency in dealing with the serious problems of TDDFT, i.e., the underestimations of Rydberg excitation energies, oscillator strengths, and charge-transfer excitation energies. By calculating vertical excitation energies of typical molecules, it was found that LC-TDDFT gives accurate excitation energies, within an error of 0.5 eV, and reasonable oscillator strengths, while TDDFT employing a pure functional provides 1.5 eV lower excitation energies and two orders of magnitude lower oscillator strengths for the Rydberg excitations. It was also found that LC-TDDFT clearly reproduces the correct asymptotic behavior of the charge-transfer excitation energy of ethylene-tetrafluoroethylene dimer for the long intramolecular distance, unlike a conventional far-nucleus asymptotic correction scheme. It is, therefore, presumed that poor TDDFT results for pure functionals may be due to their lack of a long-range orbital-orbital interaction.     

Analytic expression of the second derivatives of electronic energy for full configuration interaction wave functions

Summary A new analytic second derivative expression of the electronic energy is derived for full configuration interaction (CI) wave functions. This formula is shown to be free from the derivative terms of both CI and MO coefficients. The second-order relationships between CI and MO coefficients for full CI wave functions are also presented.     

Hole Burning and Fluorescence Spectra of Sol-Gel Derived Sm2+-Doped Glasses

Sm2+-doped glasses in the system of Al2O3-SiO2 were prepared by sol-gel processing of metal alkoxides and reacting with H2 gas at 800°C. The hole burning properties of these glasses were investigated. The holes were burned in the 7F0 5D0 line of the Sm2+ ions using a DCM dye laser at 77 K. The hole depth increased with increasing the laser irradiation time, reaching up to 15% of the total intensity within a few hundred seconds. The hole width was 3 cm–1 full width at half maximum. Fluorescence line narrowing spectra of the 5D0 7 F1 transition were analyzed to study the local structure surrounding the Sm2+ ion. It is concluded that the Sm2+ ions are closely coordinated with nine oxygens of the AlO6 group in aluminosilicate glasses and that the addition of Al3+ ions into glass induces an increase in the coordination number of the Sm2+.     

Recombinant cell bioassay systems for the detection and relative quantitation of halogenated dioxins and related chemicals

Proper epidemiological, risk assessment and exposure analysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related halogenated aromatic hydrocarbons (HAHs) requires accurate measurements of these chemicals both in the species of interest and in various exposure matrices (i.e. biological, environmental, food and feed). High-resolution instrumental analysis techniques are established for these chemicals, however, these procedures are very costly and time-consuming and as such, they are impractical for large scale sampling studies (i.e. for epidemiological studies and assessment of areas with widespread contamination). Accordingly, numerous bioanalytical methods have been developed for the detection of these chemicals in extracts from a variety of matrices, the majority of which take advantage of the ability of these chemicals to activate the aromatic hydrocarbon receptor (AhR) and the AhR signal transduction pathway. Here we review the currently available in vitro AhR-based cell bioassay systems with a focus on recent recombinant reporter gene cell lines that have been developed for detection and relative quantitation of TCDD and related HAHs. Comparison of the relative sensitivities of the various cell bioassays and examples of their use in screening and analysis of environmental, biological, and food and feed samples are presented. Currently available experimental results and validation studies demonstrate the utility of these cell bioassay systems to provide a relatively rapid, accurate, and cost effective screening approach for the detection of TCDD and related HAHs in a variety of environmental, biological, food and feed samples. The availability of these cell bioassay systems will not only facilitate the large scale sampling studies needed for accurate assessment of contamination and exposure to these environmental chemicals, but they provide avenues for the identification of novel classes of TCDD-like chemicals.     

Theoretical study of the electronic structure of the lower states of the [Cr2Cl9]3- and [Mo2Cl9]3- ions

The electronic structure of the lower states of a trigonal Cr3+ pair and Mo3+ pair, which occur in the Cs3M2Cl9 crystal (M=Cr,Mo), were studied by theoretical calculations carried out according to several methods: multireference singly and doubly excited configuration interaction, second-order configuration interaction, and multireference coupled-pair approximation. We employed a model of a [M2Cl9]3- anion embedded in a cage of point charges, which were arranged so as to simulate the anion in the crystal. The model core potential was utilized, where the relativistic effect was included for Mo. Results of the Cr complex showed that there were no direct bonds between the Cr metals. The lower electronic spectra of the [Cr2Cl9]3- ion were interpreted in terms of the electronic spectra of [CrCl6]3-. The lowest state of simultaneous excitation in both metals was considered. The [Mo2Cl9]3- ion exhibited a single direct bond between the metals. Reflecting this single bond, the observed singlet-triplet splitting was much larger than that in the case of Cr and the calculated splitting was in good agreement with the observed one. We account for the electronic spectra of the [Mo2Cl9]3- complex, which exhibited quite different features in the electronic excitation spectra in comparison with those of the Cr complex.     

Preparation and characterization of novel branched beta-cyclodextrins having beta-D-galactose residues on the non-reducing terminal of the side chains and their specific interactions with peanut (Arachis hypogaea) agglutinin

Six novel branched beta-cyclodextrins (betaCDs) having beta-D-galactose residues on the non-reducing terminal of the sugar side chains, namely 6(1),6(4)-di-O-(beta-D-galactosyl)-betaCD (10), 6-O-(beta-D-galactosyl)-betaCD (11), 6(1),6(4)-di-O-(beta-lactosyl)-betaCD (14), 6-O-(beta-lactosyl)-betaCD (15), 6(1),6(4)-di-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (18), and 6-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (19), were chemically synthesized using the trichloroacetimidate method. The reaction products were separated by HPLC on an amino column into dibranched and monobranched betaCDs. Their structures were confirmed by mass spectrometry (MS) and two-dimensional (2D) NMR spectroscopic analysis. To study the length of the sugar side chains attached to the CD ring, which leads to differences in the functions of the branched CDs, interactions of these compounds with peanut (Arachis hypogaea) agglutinin (PNA) were investigated using an optical biosensor and an inhibition assay based on hemagglutination. The results showed that all branched betaCDs interacted with PNA, and the binding affinity was 18>14>10 and 19>15>11 when the derivatives were compared on the basis of side chain length.     

Positive heterotropic cooperativity for selective guest binding via electronic communications through a fused zinc porphyrin array

Upon binding with C60 and diamines, such as 4,4'-bipyridine (bpy) and N,N,N',N'-tetramethylhexane-1,6-diamine (TMHDA), cyclic host 1 possessing two electronically coupled binding sites displays negative homotropic cooperativity and positive heterotropic cooperativity, and their ternary mixtures preferentially form inclusion complexes with hetero-guest pairs 1 supersetC60*bpy and 1 supersetC60*TMHDA under appropriate conditions. Spectroscopic titration profiles in toluene at 20 degrees C demonstrated that the association constants (Kassoc) of C60 with monodiamine complexes 1 supersetbpy (2.8 x 105 M-1) and 1 supersetTMHDA (1.5 x 105 M-1) are 8.5 and 4.5 times greater than that of C60 with guest-free 1 (3.3 x 104 M-1), respectively. On the other hand, mono-C60 complex 1 supersetC60 was 6.1 times more accessible than guest-free 1 toward TMHDA. Absorption spectroscopy in the absence of 1 indicated no direct interaction between C60 and diamines.     

Novel alkenylative cyclization using a ruthenium catalyst

Novel alkenylative cyclization of enyne was developed using Cp*RuCl(cod) under ethylene gas at room temperature.