Synthesis of oxazole based chromophores via Pd (0) catalyzed reactions: experimental and computational studies

Derivatives of aryl and hetero-aryl substituted oxazoles have several uses in agrochemicals, pharmaceuticals, and nonlinear optics (NLO). This study reports the synthesis and non-linear optical response (NLO) of three new compounds, viz., 2-(naphthalen-2-yl) oxazole (NTOZ), 2-(4-phenoxyphenyl) oxazole (PPOZ), and 2-(4'-bromo-2,2',6,6'-tetramethyl-[1,1'-biphenyl]-4-yl) oxazole (BMPOZ), for the first time by the palladium-catalyzed Suzuki coupling method. The structures of synthesized products were clarified by employing spectroscopic investigations using ¹H, & ¹³C-NMR, FT-IR, and UV-visible. The DFT studies were conducted at the M06/6-31G (d,p) functional to visualize NLO properties. Various analyses, including frontier molecular orbitals (FMOs), natural bond orbitals (NBOs), transition density matrix (TDM), and density of state (DOS), were conducted to learn more about the NLO response of the aforesaid compounds. The results indicated that the NTOZ compound showed the lowermost band gap (4.764 eV) and uppermost bathochromic shift (307.257 nm) amongst NTOZ, PPOZ, and BMPOZ. Results of global reactivity correspond with FMO outcomes such as NTOZ with a lower band gap, which displayed lower hardness (2.382 eV) and higher softness (0.2099 eV) data. Owing to the unique properties of NTOZ, significant NLO responses such as β_total = 1.3227 D and β_total = 5.47910^–30 esu were investigated, indicating it is an effective NLO material.