N. V. Krishnamurthy, A. Reddy
2006
Citations
0
Influential Citations
0
Citations
Journal
Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical
Abstract
The electronic absorption and fluorescence properties of 2,3-dihydronaphtho[1,8-de][1,2]diazepine-1,4-dione (II), 6-nitro-2,3-dihydronaphtho[ 1,8-de][ 1,2]diazepine-1,4-dione (III) and 6-amino-2,3-dihydmnaphtho[ 1,8-de][1,2]diazepine-1,4-dione (IV) have been studied in different solvents. The compounds show variation from the characteristic electronic absorption spectra of naphthalene moiety. The electron withdrawing and donating groups in III and IV facilitate longitudinal polarization causing a red shift in the 1 B b and 1 L b transitions. Proton donating solvents cause a blue shift. A new intramolecular charge transfer band is noticed as a result of capdative effect of electron donating amino substituent. The fluorescence studies show that the excitation maximum of III is always closer to that of the absorption maximum, while in IV these are separated indicating that IV undergoes association in the excited state. Stokes shifts for the substituted naphthylhydrazides vary from 33.4 to 133 nm. Compound IV exhibits larger Stokes shifts than compound III. The relative fluorescence intensities and the quantum yields of compound IV are always higher than that of III in the respective solvents. The presence of the electron donating amino group enhances the fluorescence properties of compound IV. The steady state fluorescence properties of these hydrazides do not bear any linear relationship with solvent polarity function. However, a subtle relationship is found to exist when the solvents are categorized into proton donating, accepting and inert solvents, indicating the existence of a specific interaction between the fluorophore and the solvent. Compound IV exhibits a reasonably high lifetime, which is solvent sensitive and is a better fluorophore in comparison to the other hydrazides studied.