Novel far UV-Vis absorbing bis(dihydrophenanthro[9,10-e][1,2,4] triazine) derivative dyes: Synthesis, optical, photophysical and solvatochromic properties

In this paper discussed novel fluorescent derivative dye in far UV-Vis range have been synthesized by bis-alkylation of starting compound 4, 12a-dihydrophenanthro [9, 10-e][1, 2,4]triazine-3(4H)-thione, with the appropriate dibromo compounds. and characterized by standard spectroscopic techniques. Their chemical structures were confirmed by (HNMR)-H-1, IR, MS and elemental analysis. Various optical characterizations were carried out in solvents of varying polarity. Optical parameters via extinction coefficient, absorption and emission cross-sections, fluorescence quantum yield, fluorescence lifetime, oscillator strength, the dipole moment, radiative decay rate constant, energy yield of fluorescence and the attenuation length has been determined. The effect of the spacer between two phenanthro[9,10-e] [1,2,4]triazine units in new dye and solvent polarities upon the spectral properties are discussed. The ground-state (mu(g)) and excited-state (mu(e)) dipole moments were estimated using solvatochromic correlations. The higher value of Delta mu may attribute to the singlet higher excited state of dyes which had strong intramolecular charge transfer character (ICT). (C) 2020 Elsevier B.V. All rights reserved.