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Two new Schiff‐base bismuth (III) complexes were prepared by an equivalent reaction between Schiff‐base ligand and Bi (NO3)3•5H2O with the assistance of Mannitol. The chemical structures of the two complexes were characterized by spectroscopic studies (FT‐IR, NMR, and MS), elemental analysis, and single‐crystal X‐ray diffraction. The ligand‐to‐metal ion ratio was found to be 1:1 in the complexes. During the formation of the complexes, Schiff bases changed from the amidic forms to the iminol forms, and the resulting tautomers could coordinate with bismuth (III) ions to produce dinuclear BiIII complexes(1a and 2a). Structural analyses showed that each Bi (III) ion held a distorted capped octahedron geometry with a seven‐coordinate mode in two complexes. Screening in vitro biological activities revealed that two bismuth (III) complexes exhibited much higher antimicrobial and cytotoxic activity than their parent ligands. The cytotoxic activity of the complex(1a) was close to that of the known anticancer drug (Doxorubicin) by evaluating against SGC7901 cells, with the IC50 value 0.59 μM. The complex(1a) could effectively induce SGC7901 cell apoptosis and its oral acute toxicity for LD50 value was found to be 576 mg kg−1. The content of bismuth (III) in mitochondria was higher than that in the nucleus. [ABSTRACT FROM AUTHOR]

Schiff base {(E)‐4‐((2‐hydroxy‐3‐methoxybenzylidene)amino)‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one} was prepared by the condensation reaction between 2‐hydroxy‐3‐methoxybenzaldehyde and 4‐aminoantipyrine. In the process of forming the title complex, Schiff base was first coordinated with CuII ions to form the mononuclear CuII complex (abbreviated as the complex (I)). Next, Schiff base in the complex (I) removed a phenyl group and then changed from the amide to the iminol. The tautomer further formed the complex through the iminol oxygen, and the phenolic oxygen coordinated with metal ions (CuII and BiIII). The structure of the polynuclear CuIIBiIII complex (abbreviated as the complex (II)) was identified as [Bi2Cu6 L6O3] (L = C13H13N3O3) by elemental analysis, FT‐IR spectra, and single‐crystal X‐ray diffraction analysis. The antibacterial effect of Schiff base and its complex (II) were assessed on four bacterial strains involving gram‐positive strains (S. aureus and B. subtilis) and gram‐negative strains (E. coli and P. aeruginosa). The complex (II) exhibited stronger antibacterial activity than Schiff base. Assessment of cytotoxic activity against SNU‐16 cells (Human gastric cancer) has demonstrated that the complex (II) was more active than Schiff base, and their IC50 values were 0.29 and 1.83 μM, respectively. [ABSTRACT FROM AUTHOR]

A new bismuth(III) Schiff‐base complex [Bi2(HL)2(NO3)4(CH3OH)]•2CH3OH was prepared by reaction of the equivalent molar of Schiff‐base ligand [H2L = (E)‐N′‐(2‐hydroxy‐4‐methoxybenzylidene)isonicotinohydrazide] and Bi (NO3)3•5H2O with the assistance of mannitol. The complex was structurally characterized by elemental analysis, spectroscopic methods (FT‐IR, MS, 1HNMR, and 13CNMR) and single crystal X‐ray diffraction. The molecular structure of the complex reveals that the ligand forms a 1:1 complex with bismuth(III) ion. It is composed of two 7‐coordinated bismuth(III) ions, two tetradentate O2N‐donor ligands, four nitrate ions, and three methanol molecules. The complex and its free ligand were evaluated against gram‐positive bacteria (Staphylococcus aureus, Bacillus subtilis) and gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The complex was more active than the ligand against all bacterial strains. Their cytotoxic activity was also investigated against SNU‐16 cell. The complex is approximately three times more potent than the ligand, with the IC50 values 0.35 and 1.18 μM for the complex and its ligand, respectively. [ABSTRACT FROM AUTHOR]

A new bismuth(III) Schiff‐base complex [Bi2(HL)2(NO3)4] was synthesized by using equivalent molar of Schiff‐base ligand [H2L = (E)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)isonicotinohydrazide] and Bi(NO3)3•5H2O with the assistance of Mannitol. The complex was structurally characterized by elemental analysis, spectroscopic methods, and single crystal X‐ray diffraction. The experimental and theoretical vibrational bands (infrared and Raman spectra) have been discussed. The antimicrobial activity of the complex against Schizosaccharomyces pombe was evaluated by bio‐microcalorimetry at 32°C. Some thermokinetic parameters (k, Pmax, tG, and Qtotal) were obtained from the metabolic power–time curves of S. pombe, and their quantitative relationships with the concentration (c) were discussed. The half inhibition concentrations (IC50) of isoniazid, Schiff base, and the complex were calculated. The complex showed the strongest inhibition effect among three compounds. [ABSTRACT FROM AUTHOR]

Four dinuclear bismuth(III) Schiff-base complexes bearing Schiff-base ligands have been synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis, and spectral techniques (FT-IR, NMR and MS). The analytical data reveal the bismuth(III) complexes possess 1:1 metal–ligand ratios. In vitro biological studies have revealed that bismuth(III) complexes displayed much higher antibacterial and antitumor activities than their parent ligands, which involves two gram-negative (S. aureus , B. subtili) and two gram-positive (E. coli , P. aeruginosa) bacteria, and human gastric cancer SNU-16 cells. The power–time curves of S. pombe exposed to tested compounds were detected by bio-microcalorimetry. Some thermokinetic parameters (k , P max, t G and Q total) were derived based on the metabolic power–time curves, and their quantitative relationships with the concentrations (c) were further discussed. Four dinuclear bismuth(III) Schiff-base complexes have been synthesized and characterized. The complexes possess 1:1 metal–ligand ratios and display much higher bioactivities than the ligands. Five thermokinetic parameters (k , P max, t G and Q total) were derived by the power–time curves and their quantitative relationships with the concentrations (c) were discussed. [Display omitted] • Four dinuclear Bismuth(III) Schiff-base complexes were designed and synthesized. • Upon coordination to Bi(III) antibacterial and antitumor activities increased. • Five thermokinetic parameters (k , I , P max , t G and Q total) were derived. • The complex bearing halide group display more potent biological activities. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new cobalt(II) complex was synthesized and characterized. • Theoretical studies using DFT calculations. • The bioactivity of cobalt(II) complex was assessed by bio-microcalorimetry. • The complex displayed much stronger antibacterial activity than Schiff base. • Some thermokinetic parameters (k , P max , t G and Q total) were derived. A new cobalt(II) Schiff-base complex [Co(L) 2 ] was prepared by using equivalent molar of Schiff-base ligand [HL=(E)- N '-(2-hydroxy-3-methoxybenzylidene)isonicotinohydrazide] and CoCl 2 ·6H 2 O. The structure of the complex was characterized by single-crystal X-ray diffraction, IR, ESI-MS, elemental analysis and DFT method. X-ray crystal structure analysis showed that the complex crystallized in space group Pbca, with two symmetry-independent molecules. The experimental vibrational bands(IR) have been discussed and assigned based on DFT calculations. The antibacterial activity of Schiff base and its complex against S. pombe were assessed by bio-microcalorimetry at 32 °C. Some thermokinetic parameters (k , P max, t G and Q total) were derived from the metabolic power–time curves, and their quantitative relationship with the concentration were analyzed. The half inhibition concentration (IC 50) of Schiff base and its complex were calculated to be 1.18 × 10−2 mol L−1 and 1.07 × 10−3 mol L−1, respectively. The inhibition effect of the complex showed much stronger than that of Schiff base. [ABSTRACT FROM AUTHOR]