The eleven new copper(II) and nickel(II) coordination compounds [Cu(L)Br]₂ (1), [Cu(L)Cl] (2), [Cu(L)NO₃] (3), [Ni(L)Cl] (4), [Ni(HL)₂](NO₃)₂ (5), and [Cu(A)(L)]NO₃, where A is 1,10-phenanthroline (6), 2,2′-bipyridine (7), 3,4-dimethylpyridine (8), 3-methylpyridine (9), pyridine (10) and imidazole (11) were synthesized with 3-(morpholin-4-yl)propane-2,3-dione 4-allylthiosemicarbazone (HL). The new thiosemicarbazone was characterized by NMR and FTIR spectroscopy. All the coordination compounds were characterized by elemental analysis and FTIR spectroscopy. Also, the crystal structures of HL and complexes 1, 6, 7, and 11 were determined using single-crystal X-ray diffraction analysis. Complex 1 has a dimeric molecular structure with two bromide bridging ligands, while 6, 7, and 11 are ionic compounds and comprise monomeric complex cations. The studied complexes manifest antibacterial and antifungal activities and also have an antiradical activity that, in many cases, surpasses the activity of trolox, which is used as a standard antioxidant in medicine. Copper complexes 1–3 have very weak antiradical properties (IC₅₀ > 100 µM), but nickel complexes 4–5 are strong antiradicals with IC₅₀ values lower than that of trolox. The mixed ligand copper complexes with additional ligand of N-heteroaromatic base are superior to complexes without these additional ligands. They are 1.4–5 times more active than trolox.

2-[1-Oxo-1-(piperidin-1-yl)propan-2-ylidene]- N-(prop-2-en-1-yl)hydrazinecarbothioamide (HL) and its six coordination compounds [Cu(L)X] (X = Cl⁻ (1), NO₃⁻ (2)), [Cu(A)(L)NO₃](A = 1,10-Phen (3), 2,2′-Bpy (4)), [Ni(HL)₂](NO₃)₂ (5), and [Fe(L)₂]Cl (6) are synthesized and characterized by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and single-crystal X-ray crystallography. Uncoordinated thiosemicarbazone HL shows higher antioxidant activity against 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS^+•) cation radicals compared with most of the other complexes. Complex 5 is the most active and its activity exceeds that of HL and is close to that of trolox, which is used in medicine as an antioxidant. The introduction of N-heteroaromatic bases (1,10-phenanthroline and 2,2′-bipyridine) into the inner sphere of the complex [Cu(L)NO₃] did not lead to an increase in antioxidant activity.

The six new copper(II) coordination compounds [Cu(HL¹)Cl₂] (1), [Cu(HL¹)Br₂] (2), [Cu(H₂O)(L¹)(CH₃COO)]·1.75H₂O (3), [Cu(HL²)Cl₂] (4), [Cu(HL²)Br₂] (5), [Cu(H₂O)(L²)(CH₃COO)] (6) were synthesized with 2-formyl- and 2-acetylpyridine N⁴,S-diallylisothiosemicarbazones (HL¹ and HL²). The new isothiosemicarbazones were characterized by NMR, FTIR spectroscopy, and X-ray crystallography ([H₂L²]I). All copper(II) coordination compounds were characterized by elemental analysis, FTIR spectroscopy, and molar conductivity of their 1mM methanol solutions. Furthermore, the crystal structure of complex 3 was determined using single-crystal X-ray diffraction analysis. The studied complexes manifest antibacterial and antifungal activities, that in many cases are close to the activity of medical drugs used in this area, and in some cases even exceed them. The complexes 4 and 5 showed the highest indexes of selectivity (280 and 154) and high antiproliferative activity against BxPC-3 cell lines that surpass the activity of Doxorubicin. The complexes 1–3 also manifest antioxidant activities against cation radicals ABTS^•+ that are close to that of trolox, the antioxidant agent used in medicine.

The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]₂ (1), [Cu(L)Br]₂ (2), [Cu(L)(NO₃)]₂ (3), [Cu(phen)(L)]NO₃ (4), [Ni(HL)₂](NO₃)₂·H₂O (5), [Ni(HL)₂]Cl₂ (6), [Zn(L)₂]·0.125H₂O (7), and [Fe(L)₂]Cl (8), where HL stands for 2-benzoylpyridine 4-allylthiosemicarbazone, were synthesized and characterized. ¹H, ¹³C NMR, and FTIR spectroscopies were used for characterization of the HL thiosemicarbazone. The elemental analysis, the FTIR spectroscopy, and the study of molar electrical conductivity were used for characterization of the coordination compounds 1–8. Also, the crystal structures of HL, its salts ([H₂L]Cl; [H₂L]NO₃), and complexes 1, 3, 5, 7, and 8 were determined using single-crystal X-ray diffraction analysis. Complexes 5, 7, 8 have mononuclear structures, while copper(II) complexes 1 and 3 have a dimeric structure with the sulfur atoms of the thiosemicarbazone ligand bridging two copper atoms together. Thiosemicarbazone HL and the complexes manifest antibacterial and antifungal activities. The studied substances are more active towards Gram-negative bacteria than towards Gram-positive bacteria and fungi. Complex 1 is the most active one towards Gram-positive bacteria and C. albicans, while the introduction of 1,10-phenanthroline into the inner sphere enhances the activity towards Gram-negative bacteria. Thiosemicarbazone and complexes 6 and 7 manifest antiradical activity that exceeds the activity of Trolox. HL and complex 1 manifest antiproliferative activity towards HL-60 cancer cells which exceeds the activity of their analogs with 2-formyl-/2-acetylpyridine 4-allylthiosemicarbazone.

Lucrarea conţine descrierea sintezei N4-(biciclo[2.2.1]hept-2-il)tiosemicarbazonei 2-acetilpiridinei (HL) şi a trei compuşi coordinativi ai cuprului cu acest ligand: [Cu(L)X] (X = NO3- (I), Cl- (II), CHCl2COO- (III)). Compușii obținuți au fost studiați cu ajutorul spectroscopiei RMN și FTIR, analizei elementale şi conductivităţii molare. Pentru HL și compuşii coordinativi I-III a fost studiată activitatea antibacteriană faţă de microorganisme Gram-pozitive (Staphylococcus aureus, Bacillus cereus) și Gram-negative (Escherichia coli, Acinetobacter baumannii). Coordinarea HL la ion de cupru(II) duce la creșterea activității antimicrobiene practic asupra tuturor microorganismelor studiate. Complexul I este cel mai activ față de microorganismele Gram-pozitive, iar complexul III este cel mai activ față de microorganismele Gram-negative. Activitatea antimicrobiană a acestor complecși în multe cazuri depășește activitatea Furacilinei și este practic la același nivel cu Tetraciclina față de microorganismele Gram-pozitive. Cuvinte-cheie: tiosemicarbazone, compuși coordinativi; cupru; activitate antibacteriană DOI: https://doi.org/10.59295/sum1(171)2023_27

In this paper, six new salts of 2-formylpyridine N4-allylthiosemicarbazone ([H2L]X∙nH2O, where X is NO3 – (1), NH2SO3 – (2), Cl– (3), Cl3CCOO– (4), Cl2CHCOO– (5), ClCH2COO– (6); n = 0 (1, 3, 5, 6), 1 (2, 4)) were synthesized and physico-chemically characterized by elemental analysis, molar conductivity measurements, FT-IR studies, 1H and 13C NMR. The crystal structures of compounds 1–5 were determined by single-crystal X-ray diffraction. Crystal data analysis shows that the structures of these compounds consist of protonated thiosemicarbazone H2L+, anions of acid residue, and water molecules in 2 and 4. These compounds manifest antiradical activity toward ABTS•+ cation radicals that exceeds the activity of non-protonated thiosemicarbazone HL and Trolox used in medical applications. The most active one is compound [H2L]Cl (3) with an IC50 value of 9.9 μmol/L. Density Functional Theory calculations showed that the electronic structure of cation H2L+ is more favorable for accepting electron if compared with HL.