- 作者: B. C. Kashyap; Samir K. Banerji95
- 作者服務機構: Department of Chemistry, Birla Institute of Technology & Science, Pilani (Rajasthan), India
- 中文摘要:
A study on the effect of a number of solvents, covering a broad polarity range i.e. from dioxane (D=2.20) to acetonitrile (D=38,0) has been made on the electronic transitions of N-aryl, N’-2-(5-halo-pyridyl) thioureas (where aryl=-C6H5 or O-CH3-CH6H5-, and halo= -Cl, -Br and -I). Two intense absorption maxima in the regions 270-285 nm (assigned for thiocarbonyl π-π* transition) are exhibited by all the substituted thioureas studied. The excitation energies and oscillator strengths of these transitions have been calculated. A correlation between ‘Er’ and ‘Z’(an empirical measure of solvent polarity) has been attempted. Solvent sensitivities of these compounds have also been calculated.
The effect of halo-substituents, in the pyridine ring, on the spectra of these substituted thioureas has also been studied. It has been proposed that there is a delocalization of electrons between the pyridine ring and the thioureaunit of these compounds. This delocalization of electronic charge is affected by the substitution of the halo-groups in the pyridine ring at para position to the thiourea unit which is reflected in the intensities and shifting of the absorption maxima. - 英文摘要: --
- 中文關鍵字: --
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