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A new thiosemicarbazone ligand was synthesized and characterized using spectroscopic techniques (UV-Vis and IR) and synchrotron x-ray powder diffraction. With M2+ = Mn2+, Zn2+ and Cd2+, coordination compounds of the type (M[L]2) were isolated. In the presence of sodium dithiocarbamate salts (NadiEtdtc.3H2O = sodium diethyldithiocarbamate trihydrate and Napipdtc = sodium piperidinedithiocarbamate), Zn2+ and Cd2+ were able to form ternary octahedral complexes where each metal binds a deprotonated (thiosemicarbazone) ligand, a monobasic dithiocarbamate ligand and a water molecule. In vitro biological evaluation tests of the free HL ligand and its metal complexes against selected fungal and bacterial cultures were performed. Compared with HL, the complexes displayed enhanced biological activities and ternary Zn (II) complexes displayed comparable antibacterial activities to the chloramphenicol standard.

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Synthesis and characterization of three nickel complexes [NiCl(L1)] 1, [NiCl(L2)] 2 and [NiCl(L3)] 3 are described {HL1 = 4‐(2,5‐dimethoxyphenyl)‐1‐((pyridin‐2‐yl)methylene)thiosemicarbazide, HL2 = 4‐(3‐nitrophenyl)‐1‐((pyridin‐2‐yl)methylene)thiosemicarbazide and HL3 = 4‐(2,4‐dimethoxyphenyl)‐1‐((pyridin‐2‐yl)methylene)thiosemicarbazide} and among the tridentate ligands HL3 is reported for the first time. The structures of the complexes were assigned based on CHNS microanalysis, spectroscopic (IR & UV–Vis.) data and solution conductivity studies. The absence of any magnetism for the complexes proved their square planar geometry. Single crystals of complex 1 were grown and analyzed by XRD analysis which confirmed the complex planarity as each Ni atom connects to three (two nitrogen and one sulfur) atoms from the thiosemicarbazone ligand and an additional chlorine atom. Packing of the complex 1 in the crystal lattice was proved to stabilize via intermolecular hydrogen bonds. Antimicrobial activities of 1–3 were studied in vitro against fungal and bacterial species and, in several instances, the complexes possessed improved antibacterial behavior in comparison to chloramphenicol.

Inspired by the active center of the natural [FeFe] hydrogenases, we designed a compact and precious metal‐free photosensitizer‐catalyst dyad (PS‐CAT) for photocatalytic hydrogen evolution under visible light irradiation. PS‐CAT represents a prototype dyad comprising π‐conjugated oligothiophenes as light absorbers. PS‐CAT and its interaction with the sacrificial donor 1,3‐dimethyl‐2‐phenylbenzimidazoline were studied by steady‐state and time‐resolved spectroscopy coupled with electrochemical techniques and visible light‐driven photocatalytic investigations. Operando EPR spectroscopy revealed the formation of an active [FeIFe0] species—in accordance with theoretical calculations—presumably driving photocatalysis effectively (TON≈210).