The effect of ligands on the first hyperpolarizabilities of rich d electron molecular system: iridium clusters,a TDDFT study

A systematically varied series of tetrahedral iridium clusters have been studied using a TDDFT method focusing on their electronic and nonlinear optical properties. The clusters W₂Ir₂(CO)₁₀(η⁵-C₅H₄Me)₂ (1), WIr₃(μ-dppe)(CO)₉(η⁵-C₅H₄Me (2), W₂Ir₂(μ-L)(CO)₈(η⁵-C₅H₄Me)₂(L = dppe 3, dppf 4), Ir₄(μ-L)(CO)₁₀(L = dppm 5, dppe 6, Ph₂P(CH₂)₃PPh₂ 7, Ph₂P(CH₂)₄PPh₂ 8, (Ph₂P)₂CHMe 9), Ir₄(CO)₁₀(phen)(phen = 1,10-phenanthroline) (10) exhibit the first static hyperpolarizabilities of medium magnitude (β _tot ～ 10 × 10^?30esu). The origination of β is discussed in terms of the electronic structure calculation and the expanded orbital decomposition scheme. The result suggests the origination of β for all the clusters are mainly d–d electron transitions intra metal skeleton, and d–π* electron transitions from metals to carbonyls. For cluster 5, which contains the ferrocenyl group, the main origination of β involves charge transfer from d orbitals of ferrocene to d orbirals of Ir and W.     

Modifications Induced by UV-Vis Irradiation on DNA Extract of Kiwifruit Investigated by Spectroscopic and Statistic Methods

ABSTRACT

Revealing molecular alterations induced on kiwifruit under UV-Vis irradiation requires a discussion of biochemical-cell infrared (IR) fingerprint (900 cm^?1–1800 cm^?1) bands characteristic of nucleic acids. FTIR-ATR spectroscopy and statistics and nondestructive methods for screening exposure effects induced by irradiation were used. There the irradiation influence on the main molecular bonds (i.e., ν(C-C), ν_s(PO₂?) and ν_as(PO₂?)) can be observed. Regression methods were used for statistical investigations. Two categories of variables were used: the absorbance measured at fixed wavenumber variables and the exposure dose. The bivariate correlations, partial correlations, and polynomial regression methods from SPSS were used for statistical investigations. The obtained results show that FTIR-ATR, in correlation with statistics techniques, might be useful to assess immediate radiation and oxidative-induced damage to nucleic acids. In this case IR spectroscopy can be used successfully to study conformational changes during DNA reversible denaturation especially on the sugar-phosphate vibrations domain.     

Endohedral gadolinium-containing metallofullerenes in the trifluoromethylation reaction

An efficient method for the synthesis of trifluoromethyl derivatives of endohedral gadolinium-containing metallofullerenes was proposed. High-purity (98–99%) trifluoromethyl derivatives Gd@C₈₂(CF₃)₅ (two isomers) and Gd₂@C₈₀(CF₃) have been synthesized for the first time. They were isolated and characterized by HPLC, MALDI-TOF mass spectrometry, and UV-Vis spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1457–1462, July, 2008.     

The properties of gold catalysts precursors adsorbed on the MCM-41 materials modified with Mn and Fe oxides

Silica mesoporous materials modified with manganese and iron were obtained by the hydrothermal method. Gold was introduced to pure and modified silica materials by the direct hydrothermal and impregnation methods. Nitrogen adsorption/desorption studies evidenced formation of the materials with large total surface area and mesoporous structure. Unmodified silica materials showed regular pore arrangement. The uniform porous structure was distorted in the iron or manganese containing samples. XRD, UV-Vis/DRS spectroscopy and temperature programmed reduction studies revealed changes of the nature of transition metal oxide and gold species on the different preparation stages. The oxide species after drying were strongly dispersed and partially incorporated to the silica framework. High temperature treatment led to the formation of extraframework Mn and Fe oxide species. Complex processes of gold deposition were observed during hydrothermal synthesis and impregnation of modified silica materials. The increase of the size of gold species was observed during calcination. The presence of transition metal oxides decreased sintering of gold crystallites.     

Chemical synthesis and characterization of aniline and o-anthranilic acid copolymer

The chemical co-polymerization of aniline with o-anthranilic acid (AA) to form copolymer films has been made in aqueous hydrochloric acid medium. The copolymer films were monitored by using the quartz crystal microbalance (QCM) technique. The effect of AA and its concentrations on the film formation was investigated. The results were justified by measuring the UV-Vis absorption spectra for the in situ copolymer films grown onto glass slides immersed into the polymerization media and the in situ UV-Vis absorption spectra for the copolymer in the bulk during the co-polymerization. The conductivity for the copolymer films and powder pellets at different molar ratios of aniline/AA were measured. Also, the IR spectra, X-ray diffraction and the thermal gravimetric analysis for the copolymer powder formed in the bulk in the absence and presence of AA were measured and discussed. It is found that the presence of AA affects the yield, induction period, depletion time and growth rate of the film formation. It also affects the crystallinity, and conductivity as well as the solubility of the polymer. Finally, the dopant weight fraction (w) associated with the copolymer was determined. It is almost half the value determined for the polymer in absence of AA.     

不对称双席夫碱过渡金属配合物的电子光谱和非线性光学性质的 理论研究

本文采用密度泛函理论中的M05方法对比研究了一类双席夫碱及其衍生物与金属Co、Ni和Cu配位后配合物的结构,非线性光学性质以及激发态性质. 结果表明,Co配合物的三重态,Ni配合物的二重态以及Cu配合物的单重态为最佳稳定结构. 通过最佳稳定结构计算得到的配合物非线性光学性质表明,三种金属配合物中Cu配合物表现出较高的一阶和二阶超极化率. 通过对其激发态性质分析表明在配体苯环上引入甲氧基使电子跃迁种类减少,导致超极化率下降,非线性光学性质减弱.     

Stannoxane capping derived from chiral tridentate NNO donor ligand for nickel and copper macrocycles: Comparative binding studies of stannoxane moiety and its modulated copper complex with CTDNA

Novel stannoxane type dinuclear tin complex C₁₆H₁₃N₄O₂Sn₂Cl₇ (1) and its modulated macrocyclic complexes [C₂₄H₃₆N₁₀O₃Sn₂CuCl₇] ClO₄ (2) and [C₂₄H₃₄N₁₀O₂Sn₂NiCl₇] ClO₄ (3) were synthesized and characterized by elemental analysis and various spectroscopic techniques (IR, ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, EPR and UV-Vis). ¹¹⁹Sn NMR shows the presence of two tin metal centers in different environment. The proposed pseudo-octahedral geometry of copper in complex 2 and square pyramidal geometry of nickel in complex 3 were established by the analysis of spectroscopic data. Absorption and fluorescence spectral studies and viscosity measurements have been carried out to assess the comparative binding of dinuclear stannoxane complex 1 and its modulated copper complex 2 with calf thymus DNA. The intrinsic binding constants K_b of the complex 1 and 2 were determined as 4.4 × 10⁴ M⁻¹ and 7.5 × 10⁴ M⁻¹, respectively. Cyclic voltammetric studies have also been employed to ascertain the binding of complex 2 with CTDNA. The results suggest that the complex 2 binds to CTDNA twice in the order of magnitude compared to complex 1. Interaction studies of complex 2 with guanosine 5′-monophosphate further confirm the binding via N₇ position of guanine and phosphate moiety.     

Die Natur des Farbzentrums im Manganblau

The Nature of the Colour Centre in Manganese Blue Manganese-blue is an industrial pigment with BaSO₄ as the carrier. Spectroscopic measurements in absorption, luminescence, and with electron paramagnetic resonance on manganese-blue and suitable comparative compounds give evidence, that manganese in the oxidation state +V and tetraoxocoordination is the colour centre.     

稀土配合物RE(Et2dtc)3(phen)的光谱性质

以铜试剂(NaEt2 dtc·3H2O)和邻菲咯啉(o-phen·H2O)与水合氯化稀土(RECl3·xH2O)(RE=La,Pr,Nd,Sm～Er;x=3～4)在无水乙醇中反应,制得三元固态配合物RE(Et2dtc)3(phen).IR光谱研究表明配合物中RE3+与NaEt2dtc中的硫原子和o-phen中的氮原子均双齿配位;UV光谱显示配合物中o-phen与稀土离子之间的能量传递是主要过程,配合物的最大吸收与o-phen相比有微小的红移;FS光谱表明配合物Sm(Et2dtc)3(phen)和Eu(Et2dtc)3(phen)分子内能量传递效率高,显示了很强的荧光性质.     

Electrochemical and Spectroscopic Studies on Interaction between Complex of Copper(Ⅱ) with Schiff Base Ligand and DNA

The crystal structure of ( [CuL (H2O) 2 ] (ClO4) 2 · 2H2O, CuL) (L ＝ N- (5-sulfosalicylidene)-4' -bromoaniline) was determined by means of X-ray crystallography. The interaction between CuL and salmon sperm DNA in a 0. 1 mol/L HOAc-NaOAc buffer solution (pH 5.10) was investigated by cyclic voltammetry and UV-Vis spectroscopy. A couple of redox peaks of CuL in the cyclic voltammograms(CV) can be seen at the glassy carbon electrode. It was found that the peak current of CuL decreased significantly with a negative shift of the peak potential in the presence of DNA compared with that in the absence of DNA. In addition,the decreased absorbance of CuL was observed with increasing the concentration of DNA; the absorption spectrum of an ethidium bromide(EB)-DNA system inthe presence of CuL confirms that the binding mode of CuL to DNA is different from the intercalation of EB with DNA. All the experimental results indicate that CuL can bind to DNA by electrostatic binding and form a 1:1 association complex with a binding constant of 2.72×104 L/mol.