Influence of solvents on the spectra of benzylidene malonitrile derivative and DFT calculations

• Published in: Journal of molecular structure Vol. 1177; pp. 160 - 167
• Main Authors: Hisaindee, S., Rauf, M.A., Graham, J.P., Al Daweela, M.J.S., Ali Ahmed, M.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.02.2019
• Subjects: Benzylidene malonitrile; DFT; Solvatochromism; Solvent mixture; UV/Vis spectra; Solvatochromism; Solvent mixture; Benzylidene malonitrile; DFT; UV/Vis spectra
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2018.09.054

The spectroscopic behavior of benzylidene malonitrile (BZM), a donor-π-conjugate-electron acceptor compound, is reported in various solvents. Kamlet–Taft and Catalan models were used to evaluate specific and non-specific solute-solvent interactions. Solvent polarizability (SP) was found to be the dominant factor affecting the absorption and fluorescence spectral shifts. The π →π* transitions was assigned between HOMO and LUMO, based on time-dependent density functional theoretical calculations. The dipole moment of BZM in the ground and excited states were calculated using Stokes shift and solvent polarity functions. The experimental ground state dipole moment (μg = 1.7 D) was found to be lower than that in the excited state (μe = 5.5 D). In binary solvent mixtures, BZM showed both ideal (DMSO/ethanol) and non-ideal (DMSO/acetone and DMSO/dioxane) behaviors. The formation constants in DMSO/ethanol was much lower as compared to the other two mixtures. BZM also exhibited self-quenching fluorescence which is attributed to the primary inner filter effect. [Display omitted] •Synthesis of a donor -electron acceptor molecule.•Absorption data fitted well to Kamlet-Abboud-Taft and Catalan models.•TDDFT calculations confirmed the π→π* transitions between HOMO and LUMO.•Preferential solvation was observed in binary mixtures.•Self-quenching of fluorescence was attributed to the primary inner filter effect.