Effect of substitution on the excited state photophysical and spectral properties of boron difluoride curcumin complex dye and their derivatives: A time dependent-DFT study

The optical, charge transport and electronic properties of boron difluoride curcumin (BFC) complex have been explored using the DFT (Density Functional Theory) method and B3LYP functional with the combination of 6−31 + G(d,p) as a basis set. The influence of substitution with various electron releasing and withdrawing groups on the above properties is analyzed and discussed in this work. The results reveal that the BFC complex on additional electron releasing substitution experiences redshifts in the optical transitions, and this is correlated with the dipole moment, NBO charges, HOMO-LUMO energy gap. Further, the absorption (λabs) and emission (λems) spectra of substituted and unsubstituted BFCs are calculated using Time-Dependent Density Functional Theory (TD-DFT). The results show that the electron releasing groups strongly influence the absorption and emission spectra of BFC. Electron releasing groups in BFC derivatives generate the wavelength shift (Bathochromic), but the electron-withdrawing groups in BFC don't affect the λabs and λems when compare to its original (parent) compound. The output of the research work strongly recommends that the amino, phenyl and N, N′-dimethylamino derivatives are potential candidates to act as fluorescent materials due to enhance the emission behavior of BFC and also can be used as an electron/charge transport material for organic light-emitting diodes (OLEDs). [Display omitted] •The photophysical properties of BFC complex have been theoretically investigated.•A verification calculation is performed at the B3LYP/6–31 + g(d,p) level.•The calculated absorption and fluorescence spectrum agree well with the experiment.•The ERG and EDG substituent affect the photophysical behavior of BFC differently.•BFC with ERG substitution is desirable for MO, Stokes shift, and electron transfer.