Synthesis, Antioxidant Evaluation, Density Functional Theory Study of Dihydropyrimidine Festooned Phenothiazines

A series of dihydropyrimidine decorated phenothiazine and their derivatives 7 a‐7 i possessing a diverse range of functionalities such as isopropyl, methoxy, chloro, fluoro, nitro, naphthyl have been synthesized by adopting a multistep synthetic strategy and characterized using various physical and spectroscopic techniques. Preliminary antioxidant evaluation of all the molecules has been executed and exerted activity upto 69.34% (IC 50 148 μM) with respect to the standard ascorbic acid. Computational studies of a representative molecule 7 a have also been executed and appropriate results are compared with the experimental ones. The optimized structure with their bonding features and vibrational frequencies of 7 a have been determined by employing DFT−B3LYP method with 6–311++G(d,p) basis set. The theoretically calculated and experimentally resulted vibrational frequencies of 7 a are in good harmony with each other. Further, the 1 H and 13 C chemical shifts of 7 a have been calculated by the Gauge Independent Atomic Orbital (GIAO) technique and compared with the experimental ones.