SPECTROSCOPIC AND X-RAY STRUCTURAL STUDY OF THE COPPER(II) COMPLEX WITH SCHIFF BASE BETWEEN PYRIDOXAL AND BENZYLAMINE

Synthesis, Crystal Structure, Theoretical Calculations, Antibacterial Activity, Electrochemical Behavior, and Molecular Docking of Ni(II) and Cu(II) Complexes with Pyridoxal-Semicarbazone

New Ni (II) and Cu (II) complexes with pyridoxal-semicarbazone were synthesized and their structures were solved by X-ray crystallography. This analysis showed the bis-ligand octahedral structure of [Ni(PLSC-H)₂]·H₂O and the dimer octahedral structure of [Cu(PLSC)(SO₄)(H₂O)]₂·2H₂O. Hirshfeld surface analysis was employed to determine the most important intermolecular interactions in the crystallographic structures. The structures of both complexes were further examined using density functional theory and natural bond orbital analysis. The photocatalytic decomposition of methylene blue in the presence of both compounds was investigated. Both compounds were active toward E. coli and S. aureus, with a minimum inhibition concentration similar to that of chloramphenicol. The obtained complexes led to the formation of free radical species, as was demonstrated in an experiment with dichlorofluorescein-diacetate. It is postulated that this is the mechanistic pathway of the antibacterial and photocatalytic activities. Cyclic voltammograms of the compounds showed the peaks of the reduction of metal ions. A molecular docking study showed that the Ni(II) complex exhibited promising activity towards Janus kinase (JAK), as a potential therapy for inflammatory diseases, cancers, and immunologic disorders.

Luminescence and structural properties of lanthanide complexes of Schiff bases derived from pyridoxal and amino acids

Lanthanide complexes of Schiff bases (SBs) with 1:1 and 1:2 (M:Lig) stoichiometric ratios were prepared by condensation of pyridoxal (PL) and aspartic acid (Asp) or l-histidine (His), respectively, in the presence of the appropriate metal chloride as a templating agent. These complexes were studied by optical spectroscopy and single crystal X-ray diffraction techniques. Crystallographic studies of 1:1 ([Eu(PL-Asp)(H(2)O)(4)](H(2)O)) and 1:2 ([Eu(PL-His)(2)(H(2)O)(2)]Cl(H(2)O)(4)) complexes show that Eu(III) is eight-coordinate in both structures, in a distorted square antiprism environment formed by the phenolic oxygen of PL, the nitrogen atom of carbon-nitrogen double bond, oxygen atoms of the carboxylate groups of His or Asp, and oxygen atoms of the water molecules. The main species formed in aqueous solutions containing these SBs have been determined by analysis of the luminescence spectra, lifetimes of Eu(III) excited states and vibronic interaction as well as structural features of the Eu(III) coordination sphere. Possible tetradentate coordination function of SBs in aqueous solutions with relatively high concentrations as well as the potential application of the lanthanide SB complexes as new luminescence materials are discussed.

Synthesis, characterization, and antioxidative activity of new vitamin B6 triethanolamine rare earth (III) complexes

A series of new vitamin B6 triethanolamine rare earth (III) complexes Re(PN)3(TEA)(NO3)2Cl (PN = pyridoxol; TEA = triethanolamine; Re = La1, Ce2, Pr3, Nd4, Sm5, Tb6, Dy7, Ho8, Er9, Y10), were synthesized and characterized by elemental analysis, molar conductance, TGA-DTA, UV, IR, and 1H NMR spectroscopic techniques. The suppression ratio of complexes for the hydroxyl radical (OH.) and the superoxide radical (O2-.) were determined, the results show that these complexes possess scavenging effects on OH. and O2(-.). In this paper we also discuss the effect of complex conc. for the suppression ratio on superoxide radical O2(-.).

Synthesis, characterization, and antioxidative activity of vitamin B6 rare earth (III) complexes

A series of vitamin B6 pyridoxol rare earth (III) complexes Re(PN)5Cl3. 6H2O (PN = pyridoxol; Re = La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Er, Y) were synthesized and characterized by elemental analysis, molar conductance, TGA-DTA, IR, and 1HNMR spectroscopic techniques. The antioxidative activity of complexes was determined, using the suppression ratio of activated oxygen as an indicator. The results show that the complexes have the scavenger effects for activated oxygen.

Mono-vitamin B6 complexes of palladium(II) and their interactions with nucleosides

The interactions of potassium tetrachloropalladate(II) with the B6 vitamins pyridoxal, pyridoxine, and pyridoxamine in 1:1 molar ratio have been studied. From DMF solutions, the ionic trichloro (pyridoxal or pyridoxine) palladates(II) were isolated. Pyridoxamine, on the other hand, in aqueous solutions gave the dimeric complex bis [mu-chloro-pyridoxaminato-palladium(II)]. In the first two complexes, the ligands coordinated to palladium through their pyridine nitrogen while, in the last one, pyridoxamine acted as a chelating ligand through its phenolic oxygen and aminomethyl nitrogen. All three complexes reacted with nucleosides, yielding the complexes [Pd(PL)(Nucl)Cl2], [Pd(PN)(Nucl)Cl2], and [Pd(PM-H+)(Nucl)Cl], respectively. Those complexes with one ionizable N(1)H imino proton underwent deprotonation, and the new mixed ligand complexes [Pd(PL)(Nucl-H+)Cl], [Pd(PN)(Nucl-H+)], and [Pd(PM-H+)(Nucl-H+)] were formed. In all mixed ligand complexes, the B6 vitamins maintained their coordination modes. The nucleosides, on the other hand, exhibited their usual coordination sites, i.e., in the nondeprotonated complexes, purine nucleosides coordinated only through their N7 atom. In the deprotonated complexes, they acted as bidentate ligands and coordinated through their N7 and O6 atoms. All complexes were characterized with elemental analyses, conductivity measurements, and various spectroscopic techniques.