Absorption UV-visible spectra of noble metal clusters Cu n , Ag n , Au n , n = 2−9 and 20, are investigated in the framework of the time-dependent density functional theory (TDDFT) using the long-range corrected density functionals LC-M06L and CAM-B3LYP and high-quality gaussian basis sets. Some calculations including the spin-orbit coupling are also presented. The contribution of the d electrons to the optical response is found to be lower than it is when a purely local exchange functional is used. Calculated spectra are compared to experimental ones measured on clusters embedded in rare gas matrix.

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Easily accessible compact triazole-based fluorescent compounds were characterized spectroscopically and their properties modeled by computational methods.

In this paper, we report the synthesis of new unsymmetrical azines Schiff bases. These compounds were prepared by condensation of hydrazine with different aldehydes and ketones to give (E) -2-hydroxynaphthalene-1-carbaldehyde [(1E) -2-thienylmethylene] hydrazone compound (I) and (Z) -2 -[(E) -1-(2-hydroxyphenyl) ethylidenehydrazin-1-ylidene] -1,2diphenylethanone compound (II). The method adopted consists in reacting the two different carbonyl compounds simultaneously in one step in a stepwise manner reported which is practical and cost-effective. The reaction with a minor modification in operating conditions proceeded efficiently and with excellent performance. The structure of each of the two compounds (I) and (II) was determined by the X-ray diffraction technique performed on single crystals. The asymmetric unity of the two molecules consists of one asymmetry-independent molecule. In addition, hydrogen bonds C-H ... π are observed in the compound (II). We then present a detailed DFT study based on B3LYP / 6-31G (d, p) geometric structures of compounds (I); (II) and another compound (III) also another asymmetric azine (Z) -2 -[(E) -2-benzylidenehydrazine-1-ylidene] -1,2diphenylethanone whose crystal structure is reported. The fundamental vibration wave numbers are calculated and a good agreement between the observed and calculated wave numbers is obtained. The study was extended to the HOMO-LUMO analysis to calculate the energy gap. The calculated HOMO and LUMO energy reveals that the charge is transferred into the molecule.