Abstract
The interest in the NLO response of organic compounds is growing rapidly, due to the ease of synthesis, availability, and low loss. Here, in this study, Cu(II)-catalyzed selective N-arylation of 2-aminobenzimidazoles derivatives were achieved in the presence of different bases Et3N/TMEDA, solvents DCM/MeOH/H2O, and various aryl boronic acids under open atmospheric conditions. Two different copper-catalyzed pathways were selected for N-arylation in the presence of active nucleophilic sites, providing a unique tool for the preparation of NLO materials, C-NH (aryl) derivatives of 2-aminobenzimidazoles with protection and without protection of NH2 group. In addition to NMR analysis, all synthesized derivatives (1a–1f and 2a–2f) of 5-bromo-2-aminobenzimidazole (1) were computed for their non-linear optical (NLO) properties and reactivity descriptor parameters. Frontier molecular orbital (FMO) analysis was performed to get information about the electronic properties and reactivity of synthesized compounds.
Highlights
There are 30 derivatives of 2-aminobenzimidazole registered in the world as drugs that exhibit diverse pharmacological activities, e.g., antiparasitic, antifungal, antiviral, and antiallergic [1]
2-aminobenzimidazole and its derivatives were synthesized via Chan–Lam cross-coupling reaction and analyzed theoretically for structural, spectroscopic [25], and Nonlinear optical (NLO) properties [26]
UV–VIS absorption analysis is performed by using the TD-density functional theory (DFT) method to get an insight into electronic excitation that occurs from a lower energy state to a higher energy state [52]
Summary
There are 30 derivatives of 2-aminobenzimidazole registered in the world as drugs that exhibit diverse pharmacological activities, e.g., antiparasitic, antifungal, antiviral, and antiallergic [1]. Chan–Lam coupling has been used for N-arylation of various amines, anilines, esters, imidazoles, and nitrogen-containing heterocycles [17] These days computational chemistry [18] has emerged as a well-recognized partner of experimental chemistry. Nadeem and co-workers studied benzimidazole derivatives to tune the second-order nonlinear optical molecular switching by proton abstraction. Their results illustrate that substituted compounds have robustly large off–on NLO switching with a difference in βo values of 7, 63, 85, and 75 times larger than their neutral counterparts, respectively [22]. 2-aminobenzimidazole and its derivatives were synthesized via Chan–Lam cross-coupling reaction and analyzed theoretically for structural, spectroscopic [25], and NLO properties [26]. We hope that electron-donating and withdrawing groups substitution can enhance the NLO response of the newly designed bezimidazoles, and we will obtain large first-order hyperpolarizability for these compounds
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