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To investigate the optical parameters, novel metal complexes of N-(pyridin-2-ylmethylene)methanamine (L1), obtained as Schiff base by the condensation reaction of 2-pyridinecarboxaldehyde with methylamine, and isothiocyanate {[Mn(L1)2(NCS)2], (1), [Co(L1)2(NCS)2], (2), [Ni(L1)2(NCS)2], (3)} were synthesized. FT–IR and UV–Vis spectra were applied to examine the spectral features for complexes 1,2/3 characterized by XRD/LC-HRMS. Hirshfeld surface analysis was performed to describe intermolecular interactions for complexes 1 and 2. Moreover, the CAM-B3LYP and ωB97XD/6–311 + G(d,p)//LanL2DZ levels of DFT/TD-DFT methods were used to survey optimal complex structures, spectral and nonlinear optical parameters, as well as remarkable contributions in the electronic transitions for synthesized complexes 1–3. In the mid-IR region, the mean refractive index/polarizability parameters for 1–3 were found to be 1.63/5.87 × 10–24 esu, 1.46/4.80 × 10–24 esu, and 1.50/4.48 × 10–24 esu, respectively. By considering the UV–Vis absorption parameters, the experimental refractive index, optical band gap, polarizability, optical conductivity, and third-order nonlinear optical susceptibility parameters for complexes 1–3 in methanol were examined. The maximum third-order NLO susceptibility values in the photon energies of 4.68, 4.21, and 5.25 eV were obtained at 51.65 × 10–13, 51.42 × 10–13, and 51.42 × 10–13 esu, respectively. In short, detailed experimental and corresponding theoretical spectral and optical parameters for the synthesized complexes were investigated in terms of structure–property. The NLO results display that complex 1 may be a candidate for NLO material using in data storage, telecommunications, laser technology, etc. sectors in the future. [ABSTRACT FROM AUTHOR]

In this study, synthesis, spectroscopic elucidation, and investigation of antioxidant properties of new Schiff bases based on isatin and (thio)/carbohydrazone derivatives have been reported for the first time. The structures of the synthesized compounds were elucidated by FT-IR, 1H-NMR, and 13C-NMR spectroscopic methods and elemental analysis. Their DPPH, ABTS, and CUPRAC activities were evaluated as antioxidant properties. Electronic and spectral data of the compounds were obtained by DFT calculations at the B3LYP/6–311+ +G(2d,2p) level of theory. Intramolecular interactions and charge densities on the bonds were analyzed by QTAIM and IRI calculations. In addition to parameters such as frontier molecular orbital energy eigenvalues, electronegativity, nucleophilicity index, and electrodonating power, the changes in the enthalpy of the compounds for the reactions realized through the SET mechanism were calculated to elucidate the antioxidant reactions of the compounds. Most of synthesized compounds exhibited antioxidant activities with the IC50 values ranging from 27.13 to 43.35 µM for DPPH, from 6.47 to 24.96 µM for ABTS and with the A0.50 values ranging from 9.04 to 47.52 µM for CUPRAC. Among them, compound 3, containing two hydroxyl groups, showed the strongest antioxidant activity for each assay (IC50 = 27.13 µM for DPPH, 6.47 µM for ABTS, and A0.50 = 9.04 µM for CUPRAC). The antioxidant activities of compound 3 were almost two or threefold weaker than that of BHA (IC50 = 9.55 µM for DPPH, 3.42 µM for ABTS, and A0.50 = 2.24 µM for CUPRAC), used as a standard. In addition, thiocarbohydrazone compounds exhibited higher antioxidant activity than carbohydrazones. Electron donating ability and single electron transfer enthalpy calculations predicted that thiocarbohydrazone compounds can perform SET reactions more easily than carbohydrazones. [ABSTRACT FROM AUTHOR]

The World Health Organization (WHO) report shows that diabetes mellitus (DM) will be one of the ten deadly diseases in the near future. The best way to prevent DM is to decrease blood glucose levels and keep under control; therefore, it is important to design and synthesize the effective inhibitors that can be used in the treatment of DM disease. In this respect, a series of ten metal complexes containing 6-methylpyridine-2-carboxylic acid {[Cr(6-mpa)2(H2O)2]·H2O·NO3, (1), [Mn(6-mpa)2(H2O)2], (2), [Ni(6-mpa)2(H2O)2]·2H2O, (3), [Hg(6-mpa)2(H2O)], (4), [Cu(6-mpa)2(Py)], (5), [Cu(6-mpa)2(H2O)]·H2O, (6), [Zn(6-mpa)2(H2O)]·H2O, (7), [Fe(6-mpa)3], (8), [Cd(6-mpa)2(H2O)2]·2H2O, (9), and [Co(6-mpa)2(H2O)2]·2H2O, (10)} were synthesized as α-glucosidase inhibitors. We found that the IC50 values of the synthesized complexes ranged from 0.247 ± 0.10 to > 600 μM against α-glucosidase. The spectral analyses for these complexes characterized by XRD and LC–MS/MS were also carried out by FT-IR and UV–Vis spectra. Additionally, the DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level was applied to obtain optimal molecular geometries and spectral behaviors as well as significant contributions to the electronic transitions for the complexes. The molecular docking study was also performed to display interactions between the target protein (the template structure Saccharomyces cerevisiae isomaltase) and the synthesized complexes (1–10). [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is a common degenerative disease and characterized by high blood glucose levels. Since the effective antidiabetic treatments attempt to decrease blood glucose levels, keeping glucose under control is very important. Recent studies have demonstrated that α-glucosidase inhibitor improves postprandial hyperglycemia and then reduces the risk of developing type 2 diabetes in patients. Therefore, the design and synthesis of high affinity glucosidase inhibitors are of great importance. In this regard, novel series of mixed-ligand M(II) complexes containing 2,2′-bipyridyl {[Hg(6-mpa)2(bpy)(OAc)]·2H2O, (1), [Co(6-mpa)2(bpy)2], (2), [Cu(6-mpa)(bpy)(NO3)]·3H2O, (3), [Mn(6-mpa)(bpy)(H2O)2], (4), [Ni(6-mpa)(bpy)(H2O)2]·H2O, (5), [Fe(6-mpa)(bpy)(H2O)2]·2H2O, (6), [Fe(3-mpa)(bpy)(H2O)2]·H2O, (7)} were synthesized as potential α-glucosidase inhibitors. Their effects on α-glucosidase activity were evaluated. All synthesized complexes displayed α-glucosidase inhibitory activity with IC50 values ranging from 0.184 ± 0.015 to > 600 μM. The experimental spectral analyses were carried out using FT–IR and UV–Vis spectroscopic techniques for these complexes characterized by XRD and LC–MS/MS. Moreover, the calculations at density functional theory approximation were used to obtain optimal molecular geometries, vibrational wavenumbers, electronic spectral behaviors, and major contributions to the electronic transitions for the complexes 1–7. Finally, to display interactions between the synthesized complexes and target protein (the template structure Saccharomyces cerevisiae isomaltase), the molecular docking study was carried out. [ABSTRACT FROM AUTHOR]

Co(II) complexes of 2-picolinic acid (picH) and 6-methylpyridine-2-carboxylic acid (6-MepicH) {[Co(pic)2·2H2O], (1), [Co(6-Mepic)(pic)·2H2O], (2)} were obtained and their structural and spectroscopic properties were investigated by XRD, FT–IR and UV–Vis spectroscopic techniques. The measurement of α-glucosidase inhibition of the synthesized complex 2 was fulfilled by IC50 values. In order to provide further explanations about the electronic spectral properties, TD–DFT calculations in ethanol solvent and gas phase were carried out. HSEh1PBE/6-311G(d,p) level has been used to calculate the nonlinear optics (NLO) parameters and frontier molecular orbital (FMO) energies. The experimental refractive indexes and optical band gap energies for the Co(II) complexes have been obtained using FT–IR and UV–Vis spectra, respectively. Lastly, the molecular docking study of Co(II) complexes was carried out in order to demonstrate interactions between the synthesized complexes and target protein (the template structure S. cerevisiae isomaltase). [ABSTRACT FROM AUTHOR]