It has long been known that UV–Vis/near-IR absorption spectra of
chemical compounds especially colorants influenced by the solvent
media. Therefore the absorption spectra of the colorant materials in so-
lution depend strongly on the solvent–solute interactions (charge–di-
pole, dipole–dipole, dipole–induced dipole and induced dipole–
induced dipole) and solvent nature [30,31]. In order to study of solvent
effects on spectral features of the prepared dyes 3a–e, we recorded their
absorption spectra in solvents with different polarity at a concentration
of 10−4–10−5 M at room temperature. The results are shown in Table 1.
Typical UV–vis absorption spectra of synthesized dyes 3a–e in methanol
(10−4 M) are shown in Fig. 2.