Can, Sumeyra; Cinar, Mehmet; Baris, Ozlem

Context: The structural and spectroscopic properties of drug groups can be determined using spectroscopic techniques and quantum chemical calculations. In this study, the structural and spectroscopic properties of nicardipine, a potent calcium channel blocker belonging to the dihydropyridine drug group, were investigated. For this purpose, FT-IR, Raman, NMR, and UV–Vis spectra of nicardipine hydrochloride were recorded. The ground state geometry optimization performed under vacuum conditions showed excellent agreement with X-ray diffraction (XRD) data, with root-mean-square deviations of bond lengths and bond angles calculated as 0.017 Å and 2.2°, respectively. Vibrational spectrum analysis revealed all characteristic modes, and theoretical B3LYP predictions largely agreed with experimental data. NMR spectra recorded in chloroform solvent confirmed the molecular structure of nicardipine. A comparison with previously reported data revealed significant differences in the proton NMR results, while the carbon NMR data showed consistency. The gauge-invariant atomic orbital (GIAO) method, commonly used for NMR spectrum prediction, yielded results within an acceptable error range despite minor inconsistencies arising from differences between experimental and computational conditions. In the UV–Vis spectrum of nicardipine HCl, an absorption peak corresponding to π-π* excitation was observed at 238 nm. Method: The geometric optimizations and vibration spectra of the nicardipine drug molecule were performed using the Gaussian 09 program with the B3LYP functional and the 6–311 + + G(d,p) basis set. Visualizations were performed using the GaussView 5.0 interface program. NMR spectra were recorded in chloroform solvent using the GIAO method. Molecular electrostatic potential (MEP) maps and Mulliken atomic charges were analyzed to gain deeper insight into the electronic properties.

AtıfScopus1·WoS1·OpenAlex1

İncele

Yaşar, Ahmet; YaylI, Nuran; Usta, Asu; YaylI, Nurettin

Photodimerization reactions of compounds 4-6 gave four new cyclobutane-containing compounds (7-9) with full control over the stereochemistry at the four stereogenic centers. These new cyclobutane- containing compounds had β-truxinic (7a), δ-truxinic (7b and 9), and ε-truxillic (8) structures. However, o-, m-, and p-hydroxy 4-azachalcones (1-3) did not give photochemical cyclization products under any conditions (in solvent or in their solid or molten states). Experimental data suggested the possibility of frontier orbital control over stereochemical behavior, so some theoretical calculations were performed. Full geometrical optimization of compounds 1-9 was performed via DFT B3LYP/6-31+G**, and their electronic structures were also investigated. The geometries of the singlet and triplet states were initially optimized by density functional theory (DFT) and the configuration interaction singles (CIS) B3LYP/3-21 +G**level. An additional calculation was performed for the triplet state using the ground-state geometry. The possible photochemical dimerization products of compounds 7-9 (a-g) and the intrinsic reaction coordinates (IRCs) of the reactions of compounds 4-6 were calculated theoretically by the DFT/3-21+G**method. The configurations (reactant, transition state, product, and reaction pathway) corresponding to the stationary points (minima or saddle points) were determined. The intrinsic reaction coordinates were followed to verify the energy profiles that connect each TS to the appropriate local minimum. The dimeric products expected from the calculations coincided with the dimers produced experimentally.

AtıfScopus4·WoS3·OpenAlex2

İncele