In
order to get the understanding of the behavior of dyes in different
solvents of varied polarity, the absorption spectrum of all dye were
studied in methanol and water using TD-DFT at SCC-DFTB level of theory
by utilizing parameters set org/tiorg-0-1 and solute factor of 2.7. The
UV-Vis spectra calculated for all the dyes in methanol and water
solvents is given in figure 6. The analysis exhibited a red shift in
spectral peaks as the polarity of solvent is increased which depends
upon properties of solvents and hydrogen bonding between solvent-solute
and solute-solute molecules [42,
79, 80]. The amount of solvent has also
affected the oscillator strength in addition to excitation energy of the
photoactive species.