Synthesis, solvatochromism and electric dipole moment study of coumarin-fused quinoline: experimental and quantum chemical computational investigations

Abstract

A new coumarin-fused quinoline push–pull fluorescent probe was designed, synthesized and characterized using $$^{\mathrm {1}}$$ H NMR, $$^{\mathrm {13}}$$ C NMR and mass spectrometry analysis. Electronic absorption and fluorescence studies of the synthesized probe were investigated in wide range of solvents of varying polarities, and the data were used to study its solvatochromic properties. The ground and excited state dipole moments of fluorescent probe were obtained from Bakhshiev’s and Bilot–Kawasaki’s equations by means of the solvatochromic shift method. The high value of dipole moment for the excited state over ground-state value was attributed to more polar excited state of molecule. Also, emission peak undergoes a bathochromic shift with an increase in the polarity of the solvent, confirming $${\varvec{\pi }} \rightarrow {\varvec{\pi }}{} \mathbf * $$ transition. The ground-state and excited-state dipole moments were calculated and compared using DFT calculations. Both experimental and computational studies revealed that excited-state dipole moment values are higher than corresponding ground-state value of studied compound. A new coumarin-fused quinoline push–pull fluorescent probe was designed, synthesized and characterized. The ground-state and excited-state dipole moments were calculated and compared using DFT calculations.