Abstract: Dye sensitized solar cells (DSSCs) are currently attracting widespread academic and commercial interest for the conversion of sunlight into electricity because of their low cost and high DSSCs are similar to natural photosynthesis in the initial processes involving in light-harvesting and charge separation. To gain a better understanding of the role of the sensitizer, particularly of its electronic structure and excited-state properties in the efficiency of dye-sensitized solar cell devices, we have carried out Density Functional Theory (DFT) and Time Dependent DFT (TDDFT) calculations in solution of the geometry, electronic structure and optical absorption spectra of a Chl a derivative (methyl 3-devinyl-3-carboxypyropheophorbide a; Phe a) and its Mg-Phe a and Zn-Phe a -derived sensitizers. Calculations have been performed using the B3LYP exchange correlations functional, as implemented in the Gaussian03 program package. The geometries of were first optimized in vacuum using density functional 6-311G(d) method. Solvation effects were included by means of the Conductor-like polarizable continuum model (C-PCM) in the dichloromethane solvent. There are good agreement between the experimental and the TDDFT calculated absorption spectra of three Different Chlorophyllous sensitizers. From the orbital analysis and the orbital spatial orientation of HOMO and LUMO for Phe a, Mg-Phe a and Zn-Phe a -derived sensitizers, the result shows that Phe a seems to provide higher photo-to-electric conversion efficiencies.

Abstract: Catalytic oxidation of cyclohexane by two metalloporphyrins {manganese and iron 5, 10, 15, 20-meso-tetrakis-(p-chlorophenyl) porhyrin}immobilized in mesoporous MCM-48 with TBHP in acetonitril was investigated. It was found that immobilization significantly enhances catalytic activity as compared to the homogenous system.

Abstract: We studied the description of charge-transfer excitations in [CuL₂]⁺ (L=6,6′-dimethyl-2,2′-bipyridine-4,4′-bis(propenoic acid)) dye sensitizer. This dye was studied using density functional theory (DFT), and the electronic absorption spectrum was investigated via time-dependent DFT (TD-DFT) with several hybrid functional, both in the gas phase and in acetonitrile solution. We also have investigated HOMO and LUMO levels in gas and solvent phases for these dyes. The HOMOLUMO transition describes all lowest singlet excited states. We performed TDDFT calculations at the B3LYP/6-31G(d) level of theory. Solvation effects were included by the conductor-like polarizable continuum model (CPCM ). The excitation in the range 500-800 nm of absorption spectra confirms metal-to-ligand charge-transfer (MLCT) transitions. The results of this work suggest that the copper complexes are effective as sensitizers for DSSCs and they can replace ruthenium (II) complexes.

Abstract: 1-acetyl-3-[(5-bromo-2-acetoxy-phenylmethylene)-amino]-4-oxo-imidazolidin-2-thione (2) and 5-acetyl-3-[(5-bromo-2-hydroxy-phenylmethylene)-amino]-4-oxo-imidazolidin-2-thione(3)prepared by Acylation of 3-[(5-bromo-2-hydroxy-phenylmethylene)-amino]-4-oxo-imidazolidin-2-thione(1) by different method. The reaction of 3-[(5-bromo-2-hydroxy-phenylmethylene)-amino]-4-oxo-imidazolidin-2-thione (1) with bromine in presence of glacial acetic acid resultthe 5-bromo- 3-[(5-bromo-2-hydroxy-phenylmethylene)-amino]-4-oxo -imidazolidin-2-thione (4). The Acylation of compound (4) with acetic anhydride led to formation 5-bromo-1,5-diacetyl-3-[(5-bromo-2-acetoxy-phenylmethylene)-amino]-4-oxo-imidazolidin-2-thione (5). The hydrazinolysis of compound (1) with hydrazine hydrated led to formation of 2, 4-dihydrazino-3-[(5-bromo-2-hydroxy-phenylmethyl)-amino]-imidazolidine (6). The condensation of compound (1) with different aldehyde led to formation of (7a-c). The action of acetic anhydride on compounds (7a-c) under reflux led to formation of (8a-c).

Abstract: 2-(5-Mercapto-4-phenyl-4H-[1,2,4]triazol-3-ylmethyl)-6-p-tolyl-4,5-dihydro-2H-pyridazin-3-one (3) was prepared according to the established sequenced procedures 1-3 . Subsequently by using selected alkylating agents; compounds 4a-c were prepared via regioselective S alkylation procedure4. Alternatively, compounds 5a-c were prepared via regioselective addition procedure 4 . Under Mannich condition, some interesting compounds 7a,b and 8a,b were successfully prepared. On the other hand, the azides 10 and 15 coupled with amino acid esters 11a-d and 15a- d to give amino acids derivatives 12a-d and 16a-d in good to moderate yield respectively. The structural elucidation of products is reported and also some of the products were screened for their antimicrobial activity.

Abstract: 5-(3,5-Dibromo-2-hydroxyphenyl)-2,3,4-trihydro-1,2,4-triazole-3-thione(4) and 3-[(5-bromo-or 3,5-dibromo-2-hydroxy-phenylmethylene)-amino]-4-oxo-imidazolinidin-2-thiones(7a,b)were prepared via the reaction of 2,3,5trisubstituted benzaldehyde thiosemicarbazones(2a,b)with bromine in acetic acid and ethylchloroacetate in presence of fused sodium acetate. While 5-(4-methylphenyl-2-[3,5-dibromo-2-hydroxy-phenylmethylene)-hydrazion]-thiazole(5) prepared via reaction of (2b) with 4-methyl phenacylbromide. Acylation of (2b) and (5) with acetic anhydride gave the corresponding diacetyl derivatives (3) and (6).

Abstract: The electronic, structural and spectroscopic properties of the Coumarin NKX-2697 dye in gas and water solvent by the conductor-like polarizable continuum model (CPCM) to account for soulate-solvent interactions have been investigated by means of combined DFT/TD-DFT calculations. Using time dependent density functional theory (TD-DFT), we calculate excitation energies and oscillator strengths. The spectra in the range of 470-1100 nm were found to originate from transitions.We also have investigated HOMO and LUMO levels in gas and solvent phases for this dye. Inclusion of the solvent leads to important changes of the energies and composition of the molecular orbitals of the dye.

Abstract: Molecular geometries, electronic structures, and optical absorption spectra were investigated using density functional theory (DFT) at the HF/3-21G and B3LYP/3-21G levels for heteroleptic ruthenium dye, both in the gas phase and in water solution. The vertical excitation energies were calculated within the framework of the time-dependent DFT (TD-DFT) approach, whereas the solvent effects were taken into account using the conductor like polarizable continuum model (CPCM). Our results show that the three highest occupied molecular orbitals (HOMOs) are composed of Ru 4d orbitals. The spectra in the range of 350-600 nm were found to originate from metal-to-ligand charge-transfer (MLCT) transitions. The solvent effects lead to changes in both the geometries and the absorption spectra. The results of this work suggest that Ruthenium-based complexes might be effective sensitizers for next-generation dye-Sensitized Photoelectrochemical Cell.

Abstract: 3-Nitro-4-chloroquinoline 3 was converted to the azides 5/6. The azides were cyclized on thermolysis to furoxanes 7/8. Deoxygenation to furazane 9 was achieved by reaction with triphenylphosphane. The reaction conditions were studied by differential scanning calorimetry (DSC). The azides 5/6 gave with triphenylphosphane the phosphazenes 10/11, which were cleaved to the aminoquinolone 12

Abstract: ZSM-11 samples were synthesized and treated with small amounts of Pt and Au substrates (1 & 4wt% metal). The effects of this treatment on the structural, textural, and catalytic properties of the employed zeolite were studied. The acidity of Pt and Au-containing ZSM-11 solids was determined. The techniques employed were XRD, pyridine adsorption using FTIR-technique, N2 adsorption at -196 ºC, and catalytic conversion of isopropyl alcohol at 110-275 ºC using a flow technique. The treatment of ZSM-11with Au and Pt-species resulted in a structure collapse of 23, 19 %, respectively without much affecting its crystallite size. The specific surface areas of zeolites decrease slightly by treatment with Pt and Au species while their microporosity increased from 79 to 91%. All catalysts investigated behaved as selective dehydration solids having activities which increased by treating with Pt or Au species. The samples treated with 4 wt% Pt showed the biggest activity. The selectivity towards propene formation was also found to increase by treatment with Pt or Au species.