New thiosemicarbazone Schiff base ligands: Synthesis, characterization, catecholase study and hemolytic activity

Abstract

Two novel thiosemicarbazones ligands have been synthesized and characterized by FT-IR, ESI-MS, 1 H NMR, and also by single-crystal X-ray diffraction for L1. The crystal structure shows that L1 molecules are planar and are connected via N-H-S and O-H-S interactions. The catecholase activity of is situ copper and cobalt complexes of this ligands has been investigated against 3,5-di-tert-butylcatechol. The progress of the oxidation reactions was closely monitored over time following the strong peak of 3,5-DTBC using UV-Vis. Oxidation rates were determined from the initial slope of absorbance vs. time plots, then analyzed by Michaelis-Menten equations. Catechol oxidation reactions were realized using different concentrations of copper and cobalt acetate and ligands (L/Cu: 1/1, 1/2, 2/1). The results show that all complexes were able to catalyze the oxidation of 3,5-DTBC. Acetate complexes have the highest activity. CuL1 and CoL1 complexes act as a catalyst and inhibitor. While copper and cobalt complexes obtained from ligand L2 illustrate concentration-independent oxidation activation. The hemolysis study performed by L1 increases as a function of its concentration. However, ligand L2 has no hemolytic effect.

Design, synthesis and characterization of novel Ni(II) and Cu(II) complexes as antivirus drug candidates against SARS-CoV-2 and HIV virus

“…The electronic transitions observed in ligand due to imine function of thio-semicarbazone moiety were slightly shifted on complexation with metal. UV-Vis spectra [1] of HL show two bands, first at 328 nm corresponding to n→π* transition in the thiosemicarbazone group, and second one at 367 nm corresponding to π→π* of the phenyl ring; while Ni(II) complex [Ni(L) 2 ] ( 1 ) shows peak at 295 for n→π* and at 372 for π→π*; similarly, Cu(II) complex [Cu(L) 2 ] ( 2 ) shows peak at 310 for n→π* and at 371 for π→π*. The shift of the bands due to intra ligand transitions is the result of weaking of the C=S bond and the extension of conjugation upon complexation.…”

“…Thiosemicarbazone Schiff base ligands are condensation products of thiosemicarbazide with suitable carbonyl compounds [ 1 , 2 ]. They have attracted enormous attention because of their significance in chemical and biological activities.…”

Synthesis, Characterization, DFT, and Thermogravimetric Analysis of Neutral Co(II)/Pyrazole Complex, Catalytic Activity toward Catecholase and Phenoxazinone Oxidation

“…For catecholase, the appearance of a new single peak with λmax = 390 nm ported the formation of pure o-quinone [37][38][39][40][41], as can be seen in Figure 6a. The pro reached full complexness with ˃99% conversion within the first 45 min (Figure 6b); m while, the appearance of new peaks with λmax= 433 nm during the phenoxazinone pro confirmed the formation of 2-aminophenoxazinone [38][39][40][41][42][43][44][45][46][47], as can be seen in Figure To confirm the presence of five coordination bonds around the Co(II) center in the absence of XRD-crystal and NMR measurements, Job's method of titration was applied. The UV-Vis Job's method produced a one-to-one metal-to-ligand stochiometric ratio, which supported the presence of the expected 5 coordination structure since the ligand is considered to be tridentate.…”

Synthesis, spectroscopic characterization, thermal studies, and molecular docking of novel Cr(III), Fe(III), and Co(II) complexes based on Schiff base: In vitro antibacterial and antitumor activities

“…Schiff-based ligands of thiosemicarbazones have gained significance over the decades as potential drug candidates (Nehar et al, 2020). Thiosemicarbazones are a group of compounds with numerous pharmacological applications, such as anti-inflammatory (Palaska et al, 2002), antibacterial (Plech et al, 2011), antifungal, antituberculosis (Küçükgüzel et al, 2006), antiviral (Pandeya et al, 1999), and antitumoral (de Oliveira et al, 2015 activities.…”