In this paper, synthesis and characterization of metal complexes [Cu2(L)3]ClO4 (1), [Ga(L)2]NO3·2H2O (2) and [In(L)2]NO3·H2O (3) (HL = 2-acetylpyridine N(4)-phenylthiosemicarbazone) was carried out, including elemental analysis, spectral analysis (IR, UV-vis, NMR), and X-ray crystallography. Complex 1 contains one S-bridged binuclear [Cu2(L)3]+ unit, where two Cu atoms display diverse coordination geometries: one being square planar geometry and the other octahedral geometry. Both 2 and 3 are mononuclear complexes, and the metal centers in 2 and 3 are chelated by two NNS tridentate ligands possessing a distorted octahedral geometry. Biological studies show that all the complexes possess a wide spectrum of modest to effective antibacterial activities and remarkable cytotoxicities against HepG2 cells, and 1, in particular, with an IC50 value of 0.19 ± 0.06 μM, is 113-fold and 28-fold more cytotoxic than HL and the antitumor drug mitoxantrone, respectively. In addition, 3 exhibits excellent photoluminescence properties. Upon the addition of 1 equiv of In3+ ions, a remarkable fluorescence intensity of HL and fluorescent color change (from transparent to light-green) could be observed with 365 nm light, indicating that this ligand may be used as a promising colorimetric and fluorescent probe for In3+ detection.

Two hybrids, [Ru(bpy)2(CH3CN)2]2[W10O32]·2CH3CN (RuW-1) and [Ru(bpy)3]2[W10O32] (RuW-2) (bpy = 2,2′-bipyridine), were synthesized by the reaction of (2,2′-dipyridyl)ruthenium complexes and decatungstate, under hydrothermal conditions, and characterized by IR, UV, fluorescence and transient absorption spectroscopy. The influences of the coordination environment of the centre ion, Ru(II), are compared and discussed in detail on the basis of analyzing their photophysical and photochemical properties. Kinetics experiments for the photodegradation of Rhodamine B (RhB) dye were followed with spectrophotometric analysis showing an absorbance decrease at 544 nm resulting from the cleavage of the aromatic ring of RhB. UV spectroscopy indicated that the degradation proceeds with a pseudo-first-order rate constant in the range of 10−3 to 10−2 s−1. These results demonstrate that the hybrids have effective activity and reusability for the photodegradation of RhB.

•Three Strandberg-type polyoxometalate compounds were synthesized.•Compounds 1–3 exhibit broad and effective activities against the tested cells.•Both coordination mode and the type of metal ion play significant roles in 1–3 cytotoxicity.•Compounds 2 and 3 might act as anticancer drug candidates.Three Strandberg-type polyoxometalate compounds [Cu(L)2(H2O)2]2H2[P2Mo5O23]·2CH3OH (1), [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O (2), [Cd(L)2(H2O)2]2H2[P2Mo5O23]·2CH3OH (3), (L = pyridine-2-carboxamide) have been synthesized and structurally characterized by elemental analysis, spectroscopic methods (IR and UV–vis) as well as single crystal X-ray diffraction. Single-crystal X-ray structural analyses indicate that 1 and 3 are isostructural and crystallized in monoclinic, space group I2/a. Biological studies have indicated that compounds 1–3 exhibit broad and effective activities against the tested cells. A synergistic effect involving L, metal and P2Mo5 could probably explain the improved growth-inhibiting properties. Both coordination mode and the type of metal ion play significant roles in these compounds cytotoxicity.Three Strandberg-type polyoxometalate compounds 1–3 have been synthesized and structurally characterized. Biological studies have indicated that compounds 1–3 exhibit broad and effective activities against the tested cells. Both coordination mode and the type of metal ion play significant roles in these compounds cytotoxicity.Download high-res image (155KB)Download full-size image

•The Fe3O4/Ag nanoparticles were synthesized via non-aqueous nanoemulsion process.•The nanoparticles could be dispersed in both aqueous and organic media.•The nanoparticles show high crystallinity, good magnetic and optical performance.Bi-phase dispersible Fe3O4/Ag core–shell nanoparticles were successfully synthesized via non-aqueous nanoemulsion process using the triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) as the surfactant. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirm the structure and morphology of the polymer-capped Fe3O4/Ag nanoparticles. The measurements obtained using ultraviolet-visible light absorbance spectrometry (UV-vis), vibrating sample magnetometry (VSM) demonstrate that the nanoparticles exhibit a surface plasmon resonance (SPR) absorption band around 430 nm from nanostructured Ag and a unique magnetic nature at room temperature. This kind of bifunctional optical-magnetic core–shell nanoparticles could be of interest in interfacial proximity effects due to the unique spatial nanostructure configuration and have potential applications in various areas.Bi-phase dispersible Fe3O4/Ag core–shell nanoparticles were successfully synthesized via non-aqueous nanoemulsion process. The nanoparticles had been characterized by transmission electron microscopy (TEM). As shown in above figure, the nanoparticles apparently are highly crystalline, virtually uniform and nearly spherical or polyhedral in shape.Download high-res image (139KB)Download full-size image

Multifunctional [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 (HL = pyridine-2-carboxamide) nanocomposites were successfully synthesized by combining [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O and Fe3O4 nanoparticles. The characterization was performed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray powder diffraction (XRD) and ultraviolet-visible light absorbance spectrometry (UV-vis). The XRD and TEM analyses reveal that the nanocomposites possess high crystallinity with an average particle size of ∼19.43 nm. The VSM and UV-vis demonstrate excellent superparamagnetic behavior and two well-behaved absorption bands of the nanocomposites. The adsorption activity of the nanocomposites was investigated using methylene blue, gentian violet, safranine T, fuchsin basic, methyl orange and Sudan red (III) as probe molecules, and the results reveal that the [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have selective adsorption behavior for organic dyes. The recycling performance was observed using basic fuchsin, and the results demonstrate that the nanocomposites exhibit good recyclability and high stability. The [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have a promising future for magnetic, optical and biomedical applications.

A hydrophilic inorganic porous catalyst was prepared via the hydrothermal method. The combination of [WZn3(H2O)2(ZnW9O34)2]12− and Co(II) provides a synergistical catalytic way to promote oximation of aldehyde/ketone with in situ generated hydroxylamine that initially produces an oxime, which further either dehydrates into a nitrile or undergoes a Beckmann rearrangement to form an amide.

•Cadmium(II) and indium(III) complexes containing thiosemicarbazone were synthesized.•The title complexes indicated significant cytotoxicity.•Indium(III) complex exhibited excellent luminescent property.•The free ligand can be used as a sensitive probe for In3+.Two metal complexes [Cd(L)2]·0.275H2O(1) and [In(L)2]NO3 (2) (HL = 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone) have been synthesized and structurally characterized by elemental analysis, a number of spectroscopic methods (IR, UV-vis, NMR), mass spectrometry, and X-ray crystallography. The Schiff’s base ligand forms hexacoordinated complexes having octahedral geometry for Cd(II) and In(III) complexes, respectively. The synthesized compounds were tested for antiproliferative activity and showed the ability to kill HepG2 cells (human hepato cellular carcinoma) significantly, especially 2 with IC50 = 2.02 ± 0.14 μM. Of particular note is the fact that complex 1 has ca 12-fold lower toxicity in the normal hepatocyte QSG7701 cells than in the hepatocellular carcinoma HepG2 cells. In addition, complex 2 also exhibited excellent luminescent property. Upon the addition of 1 equiv of In3+ ion, 200-fold fluorescence enhancement of HL at λem = 504 nm has been observed. Moreover, the fluorescent color change (from transparent to light-green) could be observed by naked eyes under the light of 365 nm. These findings can expand the applications of thiosemicarbazone derivatives in the fields of colorimetric and fluorescent probes.Two metal complexes [Cd(L)2]·0.275H2O(1) and [In(L)2]NO3 (2) (HL = 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone) have been synthesized and structurally characterized. Growth inhibition assays have indicated that both the free ligand and the title complexes have shown remarkable cytotoxicity and could slightly distinguish the human hepatocellular carcinoma HepG2 cells from normal hepatocyte QSG7701 cells. This ligand can be used as a sensitive probe for In3+.

Up to now, the metal complexes with thiocarbonohydrazones have been comparatively rare. Herein, three main group monometallic complexes formulated as [Bi(HL)(NO3)2(H2O)] (1), [Ga(HL)2]OAc·EtOH (2) and [(Ph)2Sn(HL)(OAc)]·DMF (3), where H2L = bis(2-acetylpyrazine)thiocarbonohydrazone, have been synthesized and characterized. The crystal structures of complexes 2 and 3 have been determined by single-crystal X-ray diffraction. Growth inhibition assays have indicated that both the free ligand and the title complexes are capable of inhibiting cell proliferation growth and could slightly distinguish the human hepatocellular carcinoma HepG2 cells from normal hepatocyte QSG7701 cells. Of particular note is the fact that the bismuth(III) complex 1 is the most active compound of this study and is 14-fold more cytotoxic than H2L with an IC50 value of 2.96 ± 0.25 μM. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Complex 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).

•Binuclear copper(II) complex 1 with two thiosemicarbazone ligands was synthesized.•1 indicates significant cytotoxicity with IC50 = 0.37 μM against K562 cells.•Its possible apoptotic mechanism has been evaluated.•These promising results are encouraging its further screening in vitro and in vivo.2-Benzoylpyridine N(4)-cyclohexylthiosemicarbazone (HL) and its binuclear copper(II) complex [Cu2(L)2(CH3COO)](ClO4) (1) have been synthesized and structurally characterized. Biological studies, carried out in vitro against human leukemia K562 cells have indicated that 1 indicates significant cytotoxicity with IC50 = 0.37 ± 0.028 μM comparable to cisplatin. Complex 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).2-Benzoylpyridine N(4)-cyclohexylthiosemicarbazone (HL) and its binuclear copper(II) complex [Cu2(L)2(CH3COO)](ClO4) (1) were synthesized and characterized. 1 indicates significant cytotoxicity with IC50 = 0.37 ± 0.028 μM against human leukemia K562 cells and promotes a dose-dependent apoptosis in HepG2 cells. Its possible apoptotic mechanism has been evaluated.

Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Here, a main group seven-coordinated bismuth(III) complex [Bi(L)(NO3)2(CH3CH2OH)] (1) (HL = 2-acetylpyridine N(4)-phenylthiosemicarbazone) has been synthesized and characterized by elemental analysis, IR, 1H NMR and single-crystal X-ray diffraction studies. The cytotoxicity data suggest that 1 exhibits higher in vitro antiproliferative activity in four human cancer cells tested. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Compound 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Here, a bismuth(III) complex [Bi(L)(NO3)2(CH3CH2OH)] (1) (HL = 2-acetylpyridine N(4)-phenylthiosemicarbazone) has been synthesized and structurally characterized. The cytotoxicity data suggest that 1 exhibits higher in vitro antiproliferative activity in four human cancer cells tested. Its possible apoptotic mechanism has been evaluated in HepG2 cells.

Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Few in vivo biological studies have been carried out in comparison to the plentiful in vitro data. Here, an interesting nine-coordinated bismuth(III) complex, [Bi(H2L)(NO3)2]NO3 [1; H2L = 2,6-diacetylpyridine bis(4N-methylthiosemicarbazone)], has been synthesized and structurally characterized. The analytical data reveal the formation of 1:1 (metal/ligand) stoichiometry. In vitro biological studies have indicated that the bismuth complex 1 has shown much higher antibacterial and anticancer activities than its parent ligand, especially with MIC = 10.66 μM against Bacillus cereus and Salmonella typhimurium and IC50 = 26.8 μM against K562 leukemia cells, respectively. More importantly, it also evidently inhibits H22 xenograft tumor growth on tumor-bearing mice (10 mg/kg; inhibitory rate = 61.6%). These results indicate that coordination to bismuth(III) might be an interesting strategy in the discovery of new anticancer drug candidates.

One dodecahedral bismuth(III) complex [Bi(HL)(NO3)3] (1) (HL = 2-acetylpyridine N(4)-pyridylthiosemicarbazone) has been synthesized and structurally characterized. The analytical data reveals the formation of 1:1 (metal:ligand) stoichiometry. The bismuth(III) ion is nine-coordinated by one electron pair (6s2) of the bismuth(III) atom, two nitrogen and one sulfur atoms from the N2S tridentate ligand and five oxygen atoms from three nitrate ions. Biological studies, carried out in vitro against eight selected bacteria, and four human cancer cells, respectively, have indicated that 1 shows better growth-inhibiting properties. Upon further investigation, 1 might produce cytotoxicity through apoptosis.

Two metal complexes formulated as [Zn(L)2]2·H2O (1) and [Bi(L)(NO3)2(CH3OH)] (2), where HL = 2-acetylpyrazine N(4)-phenylthiosemicarbazone, have been synthesized and characterized by elemental analysis, IR, MS, NMR and single-crystal X-ray diffraction studies. Biological studies, carried out in vitro against selected bacteria and the K562 leukemia cell lines, respectively, have shown that the free ligand and its two complexes may be endowed with important biological properties, especially HL with MIC = 3.90 μg/mL against Pseudomonas aeruginosa, the zinc(II) complex 1 with IC50 = 1.0 μM against K562 leukemia cell lines, respectively. The compounds HL and 1 may exert their cytotoxicity activity via induced loss of mitochondria membrane potential (MMP).2-Acetylpyrazine N(4)-phenylthiosemicarbazone (HL) and its metal complexes formulated as [Zn(L)2]2·H2O (1) and [Bi(L)(NO3)2(CH3OH)] (2) have been synthesized and structurally characterized. Biological studies, carried out in vitro against selected bacteria and the K562 leukemia cell lines, respectively, have shown that the free ligand and its complexes may be endowed with important biological properties. Compounds HL and 1 may exert their cytotoxicity via induced loss of MMP.

Transition metal complexes formulated as [Co(L)2]ClO4 (I) and [Ni(L)2] · H2O (II), where HL = pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone, have been synthesized. Complex I was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. In complex I, the ligand is N2S tridentate, coordinating to the metal center through pyridine nitrogen, imine nitrogen and sulfur atoms. Hydrogen bonds link the different components to stabilize the crystal structure. Preliminary in vitro screening indicated that the free ligand was active against various bacteria and fungi and all the tested compounds showed significant antitumor activity against K562 leukaemia cell line, and can therefore be candidates for further stages of screening in vitro and/or in vivo.

4-Cyclohexyl-1-(1-(pyrazin-2-yl)ethylidene)thiosemicarbazide (HL) and its transition metal complexes formulated as [Mn(L)2] (1) and [Ni(L)2] (2) have been prepared in 55–75% yield and characterized by elemental analysis, IR, MS, NMR and single-crystal X-ray diffraction studies. Biological activities of the synthesized compounds have been evaluated against selected Gram positive bacteria Bacillus subtilis, Gram negative bacteria Pseudomonas aeruginosa and the K562 leukemia cell line, respectively. The cytotoxicity data suggest that these compounds may be endowed with important biological properties, especially the nickel complex 2 with MIC = 31.2 μg/mL and IC50 = 0.53 μM, respectively. Effect of the free ligand and its two complexes on Mitochondria membrane potential (MMP) and PI-associated fluorescence intensity as well as their effect on cell apoptosis in K562 leukemia cell line was also studied. The tested compounds may exert their cytotoxicity activity via induced loss of MMP.4-Cyclohexyl-1-(1-(pyrazin-2-yl)ethylidene)thiosemicarbazide (HL) and its transition metal complexes formulated as [Mn(L)2] (1) and [Ni(L)2] (2) have been synthesized and characterized. Biological activities of the three compounds have been investigated against selected Gram positive bacteria Bacillus subtilis, Gram negative bacteria Pseudomonas aeruginosa and the K562 leukemia cell line, respectively. These compounds may exert their cytotoxicity activity via induced loss of MMP.Highlights► Heterocyclic thiosemicarbazone and its two complexes have been synthesized. ► These compounds exhibited significant antibacterial and antitumor activities. ► They may exert their cytotoxicity activity via induced loss of MMP.

Transition metal complexes [Mn(L)2] (I) and [Co(L)2] · (ClO4) · H2O (II), where HL = 2-acetylpyridine S-methyldithiocarbazate, have been synthesized. Complex I was characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction studies. The manganese(II) atom in complex I adopts a distorted octahedral geometry with the Schiff base coordinated to it as a uninegatively charged tridentate chelating agent via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atom. Biological studies carried out in vitro against K562 leukemia cancer cell line have shown that the free ligand and its metal complexes exhibited significant and different antitumor activity, since they exhibit IC50 values in the μM range.

Transition metal complexes [Zn(L1)2] (I) and [Mn(L2)2] (II), where HL1 = pyridine-2-carboxaldehyde S-methyldithiocarbazate, HL2 = pyridine-2-carboxaldehyde S-benzyldithiocarbazate, have been synthesized. Complex II was characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction studies. The manganese(II) atom in complex II adopts a distorted octahedral geometry with the Schiff base coordinated to it as a uninegatively charged tridentate chelating agent via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atom. Biological studies carried out in vitro against selected bacteria, fungi, and K562 leukemia cell line, respectively, have shown that the free ligands and their metal complexes exhibited distinctive differences in the biological properties. Ligand HL1 and complex I have the marked and broad antimicrobial activities compared to HL2 and complex II while only HL1 and complex II show significant antitumor activity against K562 leukemia cell line, since they exhibit IC50 values in the μM range.

2-Thiophene N(4)-methylthiosemicarbazone (HL) and its Ag(I) complex of formula [Ag6(L)6⋅ 4DMF] 1 have been synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction studies. The silver(I) complex 1 with a 1:1 metal–ligand molar ratio is an unusual hexanuclear cluster with 6 silver atoms in different environments: four silver atoms of them are considered to be 3-coordinate form, which are coordinated by two thiolate sulfur atoms and one imine nitrogen and the other two silver atoms are considered to be 4-coordinate form, which are coordinated by three thiolate sulfur atoms and one imine nitrogen, with four thiolate sulfur bridging two silver atoms and two thiolate sulfur bridging three silver atoms. Biological studies, carried out in vitro against bacteria, fungi and SMMC-7721 liver cancer cell line, respectively, have shown that the free ligand and the title complex show distinct difference in the biological property.2-Thiophone N(4)-methylthiosemicarbazone and its Ag(I) complex of formula [Ag6(L)6⋅ 4DMF] 1 were synthesized and fully characterized. The silver complex 1 is an unusual hexanuclear cluster with 6 silver atoms in different environments. Biological studies have shown that the free ligand and the title complex show distinct difference in the biological property.

2-Acetylpyridine N(4)-cyclohexylthiosemicarbazone (HL) and its manganese(II) and nickel(II) complexes formulated as [Mn(L)2] (1) and [Ni(L)2] (2) have been synthesized and characterized by elemental analysis, infrared spectra, mass spectra, and single-crystal X-ray diffraction studies. In the two complexes, the coordination polyhedron approaches an octahedron, where the two ligands coordinate to the metal via the pyridine nitrogen atom and the nitrogen and sulfur donors of the thiosemicarbazide moiety. Biological studies, carried out in vitro against selected bacteria and K562 leukaemia cell line, respectively, have shown that the free ligand and its complexes exhibited distinct differences in the biological activities.2-Acetylpyridine N(4)-cyclohexylthiosemicarbazone and its manganese(II) and nickel(II) complexes have been synthesized and fully characterized. Biological studies, carried out in vitro against selected bacteria and K562 leukaemia cell line, respectively, have shown that the free ligand and its complexes exhibited distinct differences in the biological activities.Research Highlights► In summary, 2-acetylpyridine N(4)-cyclohexylthiosemicarbazone and its manganese(II) and nickel(II) complexes were synthesized and fully characterized. ► Biological studies showed that the title three compounds all exhibited important antibacterial activities and the coupling of 2-acetylpyridine N(4)-cyclohexylthiosemicarbazone to Mn(II) and Ni(II), respectively, leads to remarkable enhancement of its antitumor activity. ► This confirms the conclusion that the complexation with metals has a synergetic effect on the biological activity of thiosemicarbazones.

•Two metal complexes [(Me)2Sn(L)(OAc)] (1), and [Pd(L)Cl] (2) have been synthesized and structurally characterized.•Two compounds can effectively inhibit the growth of HepG2 cancer cell lines at micromolar concentrations.•Complex 2 can promote the apoptosis of HepG2 cells and the apoptosis is associated with the activation of caspase-3.•These promising results are encouraging its further screening in vitro and in vivo.Two metal complexes [(Me)2Sn(L)(OAc)] (1), and [Pd(L)Cl] (2) based on 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone have been synthesized and structurally characterized. X-ray crystallography reveals that in title compounds, each thiosemicarbazone adopts tridentate NNS manner to coordinate with the metal center, and the metal coordination geometry can be described as a distorted pentagonal bipyramid in 1 and a contorted square-planar in 2, respectively. Growth inhibition assays have indicated that two compounds can effectively inhibit the growth of HepG2 cancer cell lines at micromolar concentrations. In addition, apoptosis mechanisms of 2 on HepG2 cells were further investigated. The results show that 2 can promote the apoptosis of HepG2 cells and the apoptosis is associated with the activation of caspase-3.Two metal complexes [(Me)2Sn(L)(OAc)] (1), and [Pd(L)Cl] (2) based on 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone have been synthesized and structurally characterized. Growth inhibition assays have indicated that two compounds can effectively inhibit the growth of HepG2 cancer cell lines at micromolar concentrations. In addition, apoptosis mechanisms of 2 on HepG2 cells were further investigated. The results show that 2 can promote the apoptosis of HepG2 cells and the apoptosis is associated with the activation of caspase-3.

Up to now, the metal complexes with thiocarbonohydrazones have been comparatively rare. Herein, three main group monometallic complexes formulated as [Bi(HL)(NO3)2(H2O)] (1), [Ga(HL)2]OAc·EtOH (2) and [(Ph)2Sn(HL)(OAc)]·DMF (3), where H2L = bis(2-acetylpyrazine)thiocarbonohydrazone, have been synthesized and characterized. The crystal structures of complexes 2 and 3 have been determined by single-crystal X-ray diffraction. Growth inhibition assays have indicated that both the free ligand and the title complexes are capable of inhibiting cell proliferation growth and could slightly distinguish the human hepatocellular carcinoma HepG2 cells from normal hepatocyte QSG7701 cells. Of particular note is the fact that the bismuth(III) complex 1 is the most active compound of this study and is 14-fold more cytotoxic than H2L with an IC50 value of 2.96 ± 0.25 μM. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Complex 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).

One dodecahedral bismuth(III) complex [Bi(HL)(NO3)3] (1) (HL = 2-acetylpyridine N(4)-pyridylthiosemicarbazone) has been synthesized and structurally characterized. The analytical data reveals the formation of 1:1 (metal:ligand) stoichiometry. The bismuth(III) ion is nine-coordinated by one electron pair (6s2) of the bismuth(III) atom, two nitrogen and one sulfur atoms from the N2S tridentate ligand and five oxygen atoms from three nitrate ions. Biological studies, carried out in vitro against eight selected bacteria, and four human cancer cells, respectively, have indicated that 1 shows better growth-inhibiting properties. Upon further investigation, 1 might produce cytotoxicity through apoptosis.