Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies.

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2-sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV-Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric-derivative thermogravimetric analysis, indicating its stability up to 95 °C.

Synthesis and Spectral Identification of Three Schiff Bases with a 2-(Piperazin-1-yl)-N-(thiophen-2-yl methylene)ethanamine Moiety Acting as Novel Pancreatic Lipase Inhibitors: Thermal, DFT, Antioxidant, Antibacterial, and Molecular Docking Investigations.

Three new tetradentate NNNS Schiff bases (L1-L3) derived from 2-(piperidin-4-yl)ethanamine were prepared in high yields. UV-Visible and FTIR spectroscopy were used to monitor the dehydration reaction between 2-(piperidin-4-yl)ethanamine and the corresponding aldehydes. Structures of the derived Schiff bases were deduced by 1H and 13C NMR, FTIR, UV-Vis, MS, EA, EDS, and TG-derived physical measurements. DFT/B3LYP theoretical calculations for optimization, TD-DFT, frequency, Molecular Electrostatic Potential (MEP), and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) / were performed for L2. The in vitro antimicrobial activities of the three Schiff bases were evaluated against several types of bacteria by disk diffusion test using Gentamicin as the standard antibiotic. Schiff bases revealed good antioxidant activity by the DPPH method, and the IC50 values were compared to the Trolox standard. Pancreatic porcine lipase inhibition assay of the synthesized compounds revealed promising activity as compared to the Orlistat reference.

Ultrasonic synthesis of Oct. trans-Br2Cu(N ∩ N)2 Jahn-Teller distortion complex: XRD-properties, solvatochromism, thermal, kinetic and DNA-binding evaluations.

Under mode of ultrasonic vibration, the neutral octahedral mononuclear [trans-CuBr2(N ∩ N)2]·3H2O complex with N ∩ N = 2,2-dimethylpropane-1,3-diamine was obtained. The structure of the desired complex was characterized by UV-Vis. spectroscopy, FT-IR, EDX, MS, SEM, TG/DTA and CHN-analysis. The octahedral-structure of the desired Cu(II) complex was proven via XRD single-crystal diffraction and its molecular interactions were computed by Hirschfeld surface analysis. Alcohol (as solvent) and short ultrasonic vibration dose period played a critical role in sonochemistry synthesis of octahedral neutral trans-CuBr2(N ∩ N)2 complex instead of trigonal bi-pyramidal monocation [CuBr(N ∩ N)2]Br one. Due to the Jahn-Teller effect, the complex exhibited a trans bonds elongation along Br-Cu-Br axis originating a distorted-octahedral Cu(II), as revealed by the XRD measurements (Br-Cu = 3.04 Å). Therefore, the Solvatochromic behavior of the complex was successfully performed since the trans di-bromide ions are loosely coordinated to Cu(II) center, the change in complex solutions colors by using different solvents which can be detected even by naked-eye supported atypical Jahn-Teller elongation effect formation. TG/DTA and Flynn Wall Ozawa (FWO) isoconversional kinetic methods were applied for the complex to figure out the thermal behavior, kinetic of the ligands de-structured and estimate its Ea/α relation. The complex binding mode to the CT-DNA was examined by UV-vis. spectroscopic, melting curve, CV and viscosity tests. The complex exhibited very strong DNA binding via an intercalation mode of coordination with Kb = 6.5 × 105 value.

New isomeric Cu(NO2-phen)2Br]Br complexes: Crystal structure, Hirschfeld surface, physicochemical, solvatochromism, thermal, computational and DNA-binding analysis.

Water soluble mono-cationic copper(II) complex of the general formula [Cu(NO2-phen)2Br]Br, (NO2-phen=5-nitro-1.10-phenantholine) was prepared in good yield under ultrasonic irradiation. The desired complex was isolated as a bromide salt and identified by MS, EA, UV-Vis., TG/DTA, FT-IR and XRD. The single-crystal X-ray diffraction and Hirschfield analysis revealed a square pyramidal distorted geometry around the Cu(II) center. The geometry of the [Cu(NO2-phen)2Br]+ complex was fully optimized with ab-initio methods and (DFT/B3LYP) density functional theory, then structural parameters were compared to the XRD data. The solvatochromism of [Cu(NO2-phen)2Br]Br complex was investigated in several polar solvents. Absorption and viscosity titration studies concluded that the [Cu(NO2-phen)2Br]Br complex is a very good CT-DNA binder.