1-(5-chloro-2-htdroxyphenyl)ethanone (Compound 1) is ortho-hydroxy aromatic ketone where crystal structure has been unambiguously confirmed by single crystal XRD at higher temperature (298 K). Compound 1 has been characterized by different physicochemical techniques like melting point, elemental analyses (carbon, hydrogen, chlorine & oxygen), IR, UV-Vis, mass spectroscopy. Reference Compound 1 crystallizes triclinic crystal system having space group P-1 with the values a = 7.494(4), b = 12.906(5), and c = 16.105(8) Å; α = 90.21° (2), β = 90.16° (3), and γ=90.39° (2), V=1557.7(12) Å and Z = 8. Finally crystal structure 1 was refined to R =0.1101. It is a unique crystal structure where crystal units are stabilized by intramolecular hydrogen bonding. Hydrogen bonded supramolecular network is further supported by π-π stacking interaction. The geometry of Compound 1 optimized in the singlet ground states by DFT computation (using B3LYP functional) and proper basis sets used 6-31G (d-p). Density functional theory of optimized crystal structure having Mulliken charge distribution confirmed that both carbon and oxygen utilized sp² hybridization. The molecular structure, selected bond parameters and IR, UV-Vis spectral data of Compound 1 are theoretically studied using DFT computational method. A supplementary TD-DFT calculations have been performed for optimized geometry of title Compound 1 to get deep insight into the different spectral electronic transitions.

Keywords: 2-Hydroxy-1,2-di(phenyl)ethanone; Spectral Characterization; Structure Optimization; DFT; TD-DFT;