Natural bond orbital analysis, salvation, and substituent effects of electron-releasing (–CH ₃ , –OH) and electron-withdrawing (–Cl, –NO ₂ , –CF ₃ ) groups at para positions on the molecular structure of synthesized 3-phenylbenzo[ d ]thiazole-2(3 H )-imine and its derivatives in selected solvents (acetone, toluene, and ethanol) and in the gas phase by employing the polarizable continuum method model are studied using the M06-2x method and 6-311++G(d,p) basis set. The relative stability of the studied compounds is influenced by the possibility of intramolecular interactions between substituents and the electron donor–acceptor centers of the thiazole ring. Furthermore, atomic charges, electron density, chemical thermodynamics, energetic properties, dipole moments, and nucleus-independent chemical shifts of the studied compounds and their relative stability are considered. The dipole moment values and the highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps reveal different charge-transfer possibilities within the considered molecules. Finally, natural bond orbital analysis is carried out to picture the charge transfer between the localized bonds and lone pairs.

A pharmacophore system has been found as 1,2,3-triazole, a five-membered heterocycle ring with nitrogen heteroatoms. These heterocyclic compounds can be produced using azide-alkyne cycloaddition processes catalyzed by ruthenium or copper. The bioactive compounds demonstrated antitubercular, antibacterial, anti-inflammatory, anticancer, antioxidant, antiviral, and antidiabetic properties. This heterocycle molecule, in particular, with one or more 1,2,3-triazole cores has been found to have the most powerful antifungal effects. The goal of this review is to highlight recent developments in the synthesis and structure-activity relationship (SAR) investigation of this prospective fungicidal chemical. Also there have been explained drugs and mechanism of action of a triazole compound with antifungal activity. This review will be useful in a variety of fields, including medicinal chemistry, organic chemistry, mycology, and pharmacology.

The atmospheric oxidation mechanism of imidazole initiated by hydroxyl radicals is investigated via OH-addition and H-abstraction pathways by quantum chemistry calculations at the M06-2X/aug-cc-pVTZ level of theory coupled with reaction kinetics calculations using statistical Rice–Ramsperger–Kassel–Marcus (RRKM) theory and transition state theory (TST). It was found that OH addition proceeds more rapidly than H-abstraction by several orders of magnitude. Moreover, H-abstraction reactions with submerged barriers exhibit positive temperature dependence. Effects of reaction temperature and pressure on the reaction between imidazole and OH radicals are studied by means of RRKM calculations. Effective rate coefficients involve two-step mechanisms. According to the experiment, the obtained branching ratios show that the kinetically most efficient process corresponds to OH addition onto a carbon atom which is adjacent to a nitrogen atom having a lower energy barrier. These ratios also reveal that the regioselectivity of the oxidation reaction decreases with increasing temperatures and decreasing pressures. Because of negative activation energies, pressures larger than 100 bar are required to reach the high pressure limit. The atmospheric lifetime of imidazole in the presence of OH radicals is estimated to be ∼4.74 days, based on the calculated overall kinetic rate constant of 1.22 × 10⁻¹² cm³ molecule⁻¹ s⁻¹ at a pressure of 1 bar and nearly ambient temperature. NBO analysis demonstrates that the calculated energy barriers are dictated by charge transfer effects and aromaticity changes because of the delocalization of nitrogen lone pairs to empty π* orbitals.

The oxidation reaction of oxazole initiated by OH radicals is studied via OH-addition and H-abstraction reactions using DFT (M06-2X and ωB97XD methods) under atmospheric conditions coupled with reaction kinetics calculations using transition state (TST) and Rice–Ramsperger–Kassel–Marcus (RRKM) theories. The obtained results show that OH˙ radical attack onto different carbons (OH-addition) proceeds faster than OH˙ attack onto H atoms bonded to the different carbons (H-abstraction) by several orders of magnitude. Furthermore, the pressure and temperature effects on the kinetic rates have been considered using RRKM calculations. Effective kinetic rate coefficients (k_eff) demonstrate that the two-step reaction mechanism prevails. Based on the experiment, it can be concluded that the most favorable process related to hydroxyl attack onto the carbon which is adjacent to the oxygen has a lower barrier height from a kinetic viewpoint. Branching ratios (BRs) also demonstrate that the regioselectivity decreases with decreasing pressure and increasing temperature. Despite the negative energy barriers, P > 100 bar is required in order to reach the high-pressure (H-P) limit.