Five new ?-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized their thermal photophysical behaviors analyzed. They designed through Knoevenagel condensations between arylacetylenebenzaldehydes a methylene group activated cyanoacetic malonic acids. The characterization of the target compounds was performed by Fourier transform infrared spectroscopy (FTIR), 1H nu...

Two possible isomers of some 1,3-diaryl-H-benzo[f]chromene have been studied using density functional theory. Structures of E1 and E2 isomers were optimized at the B3LYP and MP2 levels with different basis sets. The total electronic energies show that E2 isomer is about 3-5 kcal/mol more stable than E1 isomer and this energy difference is attributed to the planarity of heterocyclic ring and mor...

5(6)-Carboxy-rhodamine 110 isomers were rapidly synthesized by condensation of 3-aminophenol and trimellitic anhydride using microwave irradiation as heating method. After esterification of the two isomers, separation and hydrolyzation provided target products,5-carboxy-rhodamine 110 and 6-carboxy-rhodamine 110, in high yields. The results shows microwave irradiation can effectively reduce ...

Isolation of rotational isomer models of ethane-type molecules is described. We could experimentally prove that, if rotational isomers whose molecular shape was chiral, the molecule could be optically active, even though it did not carry an asymmetric carbon atom. As an extension, other types of stereochemically fundamental and optically active molecules were isolated and their absolute stereoc...

The structure and optical properties of a set of R-1,1'-binaphthyl-2,2'-dithiol (R-BINAS) monosubstituted A-Au38(SCH3)24 clusters are studied by means of time dependent density functional theory (TD-DFT). While it was proposed earlier that BINAS selectively binds to monomer motifs (SR-Au-SR) covering the Au23 core, our calculations suggest a binding mode that bridges two dimer (SR-Au-SR-Au-RS) ...

The static linear and nonlinear optical properties of (ZnO)N clusters of N= 2-12 are studied using finite field approach within the framework of density functional theory. Most of these clusters feature ring or cage structures in the specific size range, differing much from the wurtzite structure of bulk ZnO. The low-lying isomers with various structures possess remarkably different properties....

The optical excitations in C70 and higher fullerenes, including isomers of C76, C78, and C84, are theoretically investigated. We use a tight binding model with long-range Coulomb interactions, treated by the Hartree-Fock and configuration-interaction methods. We find that the optical excitations in the energy region smaller than about 4 eV have most of their amplitudes at the pentagons. The osc...

Mycobacillin synthetase lacks aspartic acid racemase, alanine racemase and glutamic acid racemase activities. The enzyme also does not respond to ATP-[32P]Pi exchange, nor does it catalyse the antibiotic synthesis in presence of amino acids of configuration opposite to that present in the molecule. Preincubation with optical isomers of opposite configuration inhibited the ATP-[32P]Pi exchange r...

Recently, the X-ray determined structure of the thiolated Au18 cluster has been reported. In this communication, we addressed a study of structures and chiroptical properties of thiolated Au18 cluster doped with up to ten Ag atoms, which have been calculated by Time Dependent Density Functional Theory (TD-DFT). The number of Ag atoms was steadily varied and more stable isomers showed optical an...

turally unrelated dye, fluorescein. The results obtained with this series of compounds are especially striking because the dyes differ only in the nature of the alkyl groups. Still more pronounced effects would be expected in studies of compounds having greater structural differences. Many obvious applications and extensions of these ideas are now being investigated and detailed results will be...