Fluorescent probe 7-(prop-2-yn-1-yloxy)-2H-chromen-2-one: Experimental and DFT based approach to photophysical properties

• Coumarin has high fluorescence quantum yield, large Stokes shift and excellent light stability.
• Interaction with non-polar solvents depends on the dipole-induced-dipole forces.
• In aprotic solvents the solute–solvent interaction depends on the strong dipole–dipole forces.
• UV–Vis spectrum calculated by employing time dependent density functional theory.

Compound 7-(prop-2-yn-1-yloxy)-2H-chromen-2-one was synthesized by Pechmann condensation reaction and characterized by various spectroscopic techniques. The structure of title compound was confirmed by single crystal X-ray diffraction. The compound crystallized in the orthorhombic system with P 21 21 21 space group and the corresponding lattice parameters were found to be a = 4.0138 (11) Å, α = 90°; b = 23.536 (6) Å, β = 90°; c = 10.93 (2) Å, γ = 90°. The crystal packing of molecule showed that intermolecular hydrogen bonds C3–H3⋯O3 [D = 3.53 Å], C-13–H13⋯O2 [D = 3.67 Å] and intermolecular short interaction between C1–H1⋯C1–H1 [2.68 Å] forms a dimeric unit which finally stabilizes the crystal packing in three dimensional network in the molecule. Absorption and emission spectra shows that compound is fluorescent with good Stoke shift values ranging between 57 and 62 nm. Thermal analysis further supports by TGA, DTA. The photophysical results show that the compound exhibits change in fluorescence quantum yield with change in solvent polarity. The structural parameters and the vibrational wave numbers obtained from the optimized geometry of the compound from DFT-B3LYP calculations employing 6-311G (d,p) basis set are in good agreement with the experimental data. UV–Vis spectrum calculated by employing time dependent density functional theory (TD-DFT) is also in very good agreement with the experiment for all solvents.

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