Experimental and DFT computational studies on solvatochromism of alizarin

Herein, solvatochromic behavior and excited state dynamics of alizarin in different solvents are investigated using experimental and theoretical strategies. To quantify solvent-solute interactions, spectral data are analyzed using Bakhshiev, Kausky-Chama-Violet, and Reichardt correlation models. Experimental results indicate positive solvatochromism, in which increasing polarity of solvent causes a red shift in emission spectrum, changing emission wavelength maximum from 569 nm in ethanol to 602 nm in n -hexane. Analysis by the Bilot-Kawski approach showed that dipole moment increases significantly during excitation process. These changes are calculated from 2.47 D ( μ g ) to 4.77 D ( μ e ) for nonpolar solvents and from 3.2 D ( μ g ) to 5.7 D ( μ e ) for polar solvents. To evaluate significance of these observations, comprehensive TD-DFT simulations are performed, which are in good agreement with experimental data. Computational findings showed that polar solvents play a key role in facilitating intramolecular charge transfer (ICT) by reducing transition energy gap (from 5.33 eV in n -hexane to 2.94 eV in ethanol). Furthermore, calculation of photophysical parameters showed a high light harvesting efficiency (LHE) up to 0.81 in ultraviolet region and an increase in excited state lifetime up to 9.68 ns in specific solvents, indicating high potential of alizarin for applications in optoelectronic systems. • Solvatochromism of alizarin in different solvents is investigated. • Spectral data are analyzed by Bakhshiev, Kausky-Chama-Violet, and Reichardt models. • Alizarin indicate positive solvatochromism by increasing polarity of solvent. • TD-DFT simulations are in good agreement with experimental data. • Polar solvents facilitate intramolecular charge transfer by reducing transition energy gap.