Synthesis,characterization, and crystal structures of two novel ion-pair complexes based on benzene-1,2-dithiolate ligand

Two novel ion-pair complexes, [IBzPy][Ni(Bdt)₂] (I) and [IBzDMPy][Ni(Bdt)₂] (II) (IBzPy = 1-(4-iodobenzyl)pyridinium, IBzDMPy = 1-(4-iodobenzyl)-3,5-dimethyl-pyridinium, and Bdt = benzene-1,2-dithiolate), have been synthesized and characterized by elemental analysis, IR, cyclic voltammetry, and X-ray single-crystal structure determination. The crystal structure determination reveals that the central Ni atoms in complexes I and II are in slightly distorted square-planar coordination environment. The cyclic voltammetric studies show that there are two oxidation peaks for complexes I and II, which are attributed to Ni(IV/III) and Ni(III/II) redox couples.     

Electrochemical synthesis and magnetic studies of neutral transition metal imidazolates and pyrazolates

Summary The single-step electrochemical synthesis of neutral transition metal complexes of imidazole, pyrazole and their derivatives has been achieved at ambient temperature. The metal was oxidized in an Me₂CO solution of the diazole to yield complexes of the general formula: [M(Iz)₂] (where M = Co, Ni, Cu, Zn; Iz = imidazolate); [M(MeIz)₂] (where M = Co, Ni, Cu, Zn; MeIz = 4-methylimidazolate); [M(PrⁱIz)₂] (where M = Co, Ni, Cu, Zn; PrⁱIz = 2-isopropylimidazolate); [M(pyIz)_n] (where M = Co^III, Cu^II, Zn^II; pyIz = 2-(2-pyridyl)imidazolate); [M(Pz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; Pz = pyrazolate); [M(ClPz)_n] and [M(IPz)_n] (where M = Co^III, Ni^II, Cu^II, Zn^II; ClPz = 4-chloropyrazolate; IPz = 4-iodopyrazolate); [M(Me₂Pz)_n] (where M = Co^II, Cu^I, Zn^II; Me₂Pz = 3,5-dimethylpyrazolate) and [M(BrMe₂Pz)_n] (where M = Co^II, Ni^II, Cu^I, Zn^II; BrMe₂Pz = 3,5-dimethyl-4-bromopyrazolate). Vibrational spectra verified the presence of the anionic diazole and electronic spectra confirmed the stereochemistry about the metal centre. Variable temperature (360-90 K) magnetic measurements of the cobalt and copper chelates revealed strong antiferromagnetic interaction between the metal ions in the lattice. Data for the copper complexes were fitted to a Heisenberg (S= ) model for an infinite one-dimensional linear chain, yielding best fit values of J=–62––65cm^–1 andg = 2.02–2.18. Data for the cobalt complexes were fitted to an Ising (S= ) model with J=–4.62––11.7cm^–1 andg = 2.06–2.49.     

(18-Crown-6)potassium tetrachloroferrate(III), dibromodichloroferrate(III), and tetrabromoferrate(III): Synthesis and crystal structures

Three new crystalline complexes are synthesized: [K(18-crown-6)]⁺ · An, where An = [FeCl₄]^?(I), [FeBr₂Cl₂]^? (II), and [FeBr₄]^? (III). The crystals of compounds I–III are cubic and isomorphic, space group Fd $ \bar 3 Three new crystalline complexes are synthesized: [K(18-crown-6)]⁺ · An, where An = [FeCl₄]⁻(I), [FeBr₂Cl₂]⁻ (II), and [FeBr₄]⁻ (III). The crystals of compounds I–III are cubic and isomorphic, space group Fd (Z = 16): a = 20.770(2) ? for I, 20.844(3) ? for II, and 20.878(4) ? for III. Structures I–III are solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.047 (I), 0.059 (II), and 0.098 (III) for all 680 (I), 684 (II), and 686 (III) independent reflections. In two tetrahedral anions [Fe(1)X₄]⁻ and [Fe(2)X₄]⁻ in structures I–III, all halogen atoms (X = Cl and Br) are randomly disordered over three close positions relative to the crystallographic axes 3. Structures I–III contain the [K(18-crown-6)]⁺ host-quest complex cation. The K⁺ cation (CN = 8) resides in the cavity of the 18-crown-6 ligand and coordinated by its six O atoms and two disordered halogen X atoms. The coordination polyhedron of the K⁺ cation in complexes I–III is a distorted hexagonal bipyramid. Original Russian Text ? A.N. Chekhlov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 9, pp. 1566–1570.     

Monomeric [Ni(2,2"-Bipy){(i-C4H9)2PS2}2] and [Ni(Pz)2{(i-C4H9)2PS2}2] and Polymeric [Ni(Pz){(i-C4H9)2PS2}2]nComplexes (Pz = Pyrazine): Synthesis,Structures, and Properties

Diamagnetic [Ni(i-Bu₂PS₂)₂] compound (I) in ethanol reacts with 2,2"-bipyridine or pyrazine to give the paramagnetic complexes [Ni(2,2"-Bipy)(i-Bu₂PS₂)₂] (II), [Ni(Pz)₂(i-Bu₂PS₂)₂] (III), and [Ni(Pz)(i-Bu₂PS₂)₂] _n (IV) (_eff= 2.91–3.12 _B). Single crystals of IIwere grown for X-ray diffraction study. The crystals are monoclinic, a= 14.669(3) Å, b= 19.693(4) Å, c= 12.155(2) Å, = 107.51(3)°, V= 3348(1) ų, Z= 4; _calcd= 1.257 g/cm³, space group P2₁/c. The structure is built from monomeric molecules. The coordination polyhedron of the Ni atom is a distorted octahedron formed by four S atoms of two bidentate chelating i-Bu₂PS^– ₂ligands and by two N atoms of bidentate cyclic 2,2"-Bipy. Preliminary data for complexes IIIand IVindicate that they also contain an octahedral NiN₂S₄fragment. The structures of complexes I(square planar) and ofII–IV(octahedral) were confirmed by data from electron spectroscopy. Electronic absorption spectra were used to determine the rankings of the i-Bu₂PS^– ₂ions and Pz on a spectrochemical scale.     

Synthesis and Structure of Copper(II) Complexes with Methyl [(Pyrazolo-1-carbothioyl)-amino]propionate Derivatives

Methyl 3-[(3,5-dimethylpyrazole-1-carbothioyl)-amino]propionate (L¹) and the optically active derivative of natural monoterpene (+)-3-carene, (3bS,4aR)-3-[(3,4,4-trimethyl-3b,4,4a,5-tetrahydro-cyclopropa[3,4]cyclopenta[1,2-c]pyrazole-1-carbothioyl)-amino]propionate (L²), are synthesized. The paramagnetic CuL¹Cl₂ (I) and [Cu₂L² ₂Cl₄] (II) complexes are obtained. According to the X-ray diffraction data, in mononuclear complex I, the L¹ molecule performs a bidentate-cyclic function due to the coordination of the S atom of the C=S group and the N atom of the pyrazole cycle. The CuCl₂NS coordination polyhedron is a distorted tetrahedron. Two molecules of complex I form an associate due to weak Cu···S interactions. Compound II is binuclear due to the bridging function of two Cl^- ions, and analogous functions of the L¹ and L² ligands. The coordination polyhedron in complex II is CuCl₃NS. The _eff values for compounds I and II are equal to 1.81 and 1.79 _B, respectively, and are constant in the interval from 78 to 300 K, indicating that noticeable exchange interactions between unpaired electrons of the Cu²⁺ ions are absent. The EPR spectra of the complexes in the solid phase are examined.     

The coordination chemistry ofN,N′-ethylenebis(2-acetylpyridine imine) andN,N′-ethylenebis(2-benzoylpyridine imine); two potentially tetradentate ligands containing four nitrogen atoms

Summary New complexes of the general formulae [ML_A(H₂O)₂]-Cl₂ (M=Ni or Cu), [ML_AX₂] (M=Co or Cu; X=Cl or Br), [NiL_ABr₂]·H₂O, [ML_A] [MCl₄] (M=Pd or Pt), [NiL_B(H₂O)₂]Cl₂·2H₂O, [ML_BCl₂] (M=Co, Ni, Cu, Pd or Pt; X=Cl or Br) and [ML_B] [MCl₄] (M=Pd or Pt), where L_A=N,N-ethylenebis(2-acetylpyridine imine) and L_B=N, N-ethylenebis(2-benzoylpyridine imine), have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, t.g./d.t.g. methods, magnetic susceptibilities and spectroscopic (i.r., far-i.r., ligand field,¹Hn.m.r.) studies. Monomeric pseudo-octahedral stereochemistries for the Co^II, Ni^II and Cu^II complexes andcis square planar structures for the compounds [ML_BX₂] (M=Pd or Pt; X=Cl or Br) are assigned in the solid state. The molecules L_A and L_B behave as tetradentate chelate ligands in the Co^II, Ni^II, Cu^II and Magnus-type Pd^II and Pt^II complexes, bonding through both the pyridine and methine nitrogen atoms. A bidentateN-methine coordination of the Schiff base L_B is assigned in the [ML_BX₂] complexes (M=Pd or Pt; X=Cl or Br). The anomalous magnetic moment values of the Co^II complexes are discussed.     

Synthesis,spectral and thermal studies of monomeric,homobimetallic and polymeric complexes containing benzoyldithiocarbazate

New mixed ligand complexes of benzoyldithiocarbazate (H₂BDT) have been synthesized and characterized by elemental analyses, spectral studies (i.r., u.v.–vis., mass), thermal analysis and electrical conductivity measurements. The complexes have the general formulae: [M₂(BDT)(OX)₂] · xH₂O; [Co₂(BDT)(OX)₂(H₂O)₄]; [M(HBDT)(OX)-(H₂O)], [Ni(BDT)(py)₂] _n and [Ni(BDT)(L)] _n where M = Mn^II, Ni^II and Cu^II; BDT = dithiocarbazate dianion; OX = 8-hydroxyquinolinate; x = 1 or 2; M = Zn^II or Cd^II; HBDT = dithiocarbazate anion and L = 2,2-bipyridyl or 1,10-o-phenanthroline. For the [M₂(BDT)(OX)₂] · xH₂O, [Co₂(BDT)(OX)₂(H₂O)₄], [Ni(BDT)(py)₂] _n and [Ni(BDT)(L)] _n complexes, benzoyldithiocarbazate acts as a dibasic-tetradentate ligand in the enol form via the enolic oxygen, the hydrazide nitrogens and the thiolate sulphur, while it acts as a monobasic-tridentate ligand in the keto form in the [M(HBDT)(OX)(H₂O)] complexes. The thermal behaviour of the complexes has been studied by t.g.–d.t.g. techniques. Kinetic parameters of the thermal decomposition process have been computed by Coats–Redfern and Horowitz–Metzger methods. It is obvious that the thermal decomposition in the complexes occurs directly at the metal–ligand bonds except for the Zn^II and Cd^II complexes in which decomposition seems to be at a point in the benzoyldithiocarbazate moiety. From the calculated kinetic data it can be concluded that the dehydration processes in all complexes have been described as phase-boundary controlled reactions. The activation energy values reveal that the thermal stabilities of the homobimetallic complexes lie in the order: Mn^II < Ni^II < Co^II, while the monomeric Cd^II complex has more enhanced thermal stability than the Zn^II complex.     

Copper(II) Complexes with Ethyl [(Pyrazolo-1-carbothioyl)-amino]acetate Derivatives: Synthesis and Structure

Optically active derivative of the natural monoterpene (+)-3-carene, namely, ethyl (3bS,4aR)-[(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[1,2-c]pyrazole-1-carbothioyl)-amino]acetate (HL¹) and ethyl [(3,5-dimethyl-pyrazole-1-carbothioyl)-amino]acetate (HL²) were synthesized. Paramagnetic complexes [CuL¹Cl] _n (I) and [Cu₂L² ₂Cl₂] (II) were prepared. According to X-ray diffraction data, complex Iwith anion of (+)-3-carene derivative has chain structure, whereas complex IIwith anion of HL², which has no carbocyclic fragments, is a pseudodimer. Organic anions act as tetradentate bridging, cyclic ligands forming five-membered CuN₃C and CuNOC₂metal cycles. Coordination polyhedron of Cu(ClN₂O + S) in complexes Iand IIis a square pyramid. The values of _efffor complexes Iand II(1.88 and 1.84 _B, respectively) are constant in the temperature interval 78–300 K, which means that the unpaired electrons of Cu(II) ions do not exhibit any noticeable exchange interactions.     

Redox Behaviour of Cymantrene Fischer Carbene Complexes in Designing Organometallic Multi‐tags

A series of Group 7 Fischer carbene complexes, [Cp(CO)₂Mn^I=C(OEt)Ar] (Cp=cyclopentadienyl, Ar=Th=thienyl ( 1 a ), Ar=Fu=furyl ( 2 a ), Ar=Fc=ferrocenyl ( 3 a )) and biscarbene complexes, [Cp(CO)₂Mn?C(OEt)?Ar′?(OEt)C?Mn(CO)₂Cp] (Ar′=Th′=2,5‐thienylene ( 1 b ), Ar′=Fu′=2,5‐furylene ( 2 b ), Ar′=Fc′=1,1′‐ferrocendiyl ( 3 b )) was synthesized and characterized. Chemical oxidation of [Cp(CO)₂Mn?C(OEt)Fc] ( 3 a ) and isolation of the oxidised species [3 a][PF₆] possessing a Mn^II centre proved possible below ?30 °C in dichloromethane solution. The ESR spectrum of the transiently stable radical cation, [3 a][PF₆] , confirmed the presence of a low‐spin Mn^II centre characterized by a rhombic g tensor (g_x=1.975, g_y=2.007 and g_z=2.130) in frozen dichloromethane at 77 K with ⁵⁵ Mn hyperfine coupling constants A₁, A₂ and A₃ of 115, 33 and 43 G, respectively. Electrochemical studies demonstrated the influence of the Ar substituent on the oxidation potential. All complexes showed that the redox potentials of carbene double bond reduction and Mn^I oxidation were dependent on the type of Ar group, but only 3 b showed resolved oxidations for the two Mn^I centres. Surprisingly, Mn^I oxidation occurs at lower potentials than ferrocenyl oxidation. Density functional theory (DFT) calculations were carried out to delineate the nature of the species involved in the oxidation and reduction processes and clearly confirm that oxidation of Mn^I is favoured over that of ferrocene.     

Crystal Structure of Thallium Tridecafluorotetraantimonate(III) TlSb4F13

The crystal structure of thallium fluoroantimonate(III) complex TlSb₄F₁₃ (I), which is isostructural to KSb₄F₁₃ (II), is determined. Crystals I are tetragonal: a = 9.634(2) Å, c = 6.590(2) Å, V = 611.7(2) ų, Z = 2, (calcd) = 5.094 g/cm³, F(000) = 804.0, space group I4¯. The structure consists of tetrameric [Sb₄F₁₃]^– anions formed by SbF₃ groups connected by the fluoride ion and the l⁺ cations.     

Transition metal complexes with thiosemicarbazide-based ligands,Part II,Synthesis and characterisation of nickel(II), cobalt(II), manganese(II) and zinc(II) complexes with the pentadentate ligand, 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone)

Summary The reaction of warm alcoholic solutions of acetates of Co^II, Mn^II, Zn^II and Ni^II with 2, 6-diacetylpyridine andS-methylisothiosemicarbazide hydrogen iodide yielded the complexes: [Co(H₂L)I₂]·H₂O, [Mn(H₂L)(MeOH)₂]I₂, [Zn(H₂L)(MeOH)I]I and [Ni(HL)]I, (H₂L=the pentadentate pentaaza-ligand 2, 6-diacetylpyridine bis(S-methylisothiosemicarbazone)). The reaction of methanolic solutions of [Ni(HL)]I and NH₄NCS or LiOAc.2H₂O, give [Ni(HL)]NCS and NiL, respectively. For the complexes of Co^II, Mn^II and Zn^II, a pentagonal bipyramidal configuration is proposed, with H₂L in the equatorial plane and two unidentate ligands (I and/or MeOH) in the axial positions. The complexes [Ni(HL)]X (X=I or NCS) and NiL probably have monomeric five- and dimeric six-coordinate structures, respectively, in which only the chelate ligand is involved in coordination.     

Electronic State of Rhenium Complexes with Octahedral Chalcocyanide Cluster Anions [Re6Q8(CN)6]3– (Q = S,Se, Te). EPR and Magnetic Susceptibility Studies

Compounds (Ph₄P)₃[Re₆S₈(CN)₆] (I), (Ph₄P)₂(H)[Re₆Se₈(CN)₆] · 4H₂O (II), and (Bu₄N)₂(H)[Re₆Te₈(CN)₆] · 2H₂O (III) were synthesized and studied using EPR spectroscopy and magnetic susceptibility methods. The [Re₆Q₈(CN)₆]^3– cluster anions (Q = S, Se, Te) were found to be paramagnetic; at 300 K, _eff of complexes I, II, and III is equal to 2.01, 1.90, and 1.96 _B, respectively. Magnetic susceptibility measured in the 2–300 K range suggested insignificant exchange interaction between paramagnetic centers. The parameters of the EPR spectra of complexes I and II (g = 2.51 and 2.56; H = 330 and 460 G, respectively) indicated that the unpaired electron is located near S or Se atoms.     

Synthesis and structure of optically active compounds [Ni(HL1)]NO3 and [Ni(HL2)]NO3H2O containing anions of diaminodioximes H2L1 and H2L2 derived from α-Pinene and (+)-3-Carene as Ligands

New optically active levorotatory compounds [Ni(HL¹)]NO₃ (I) and [Ni(HL²)]NO₃H₂O (II) containing the anions of chiral diaminodioximes, H₂L¹ and H₂L², derived from the terpenes ±-pinene and (+)-3-carene, respectively, were synthesized. Complexes I and II were studied by X-ray diffraction. The crystal structures of compounds are ionic, being composed of the [Ni(HL¹)]⁺ or [Ni(HL²)]⁺ cations and the outer-sphere NO₃^– anions. The Ni²⁺ ion coordinates four N atoms of the tetradentate chelating ligand, the NiN₄ coordination unit being shaped like a tetrahedrally distorted square. Compounds I and II are diamagnetic, which corresponds to a low-spin d⁸ configuration. The NMR spectra of compounds were recorded and analyzed.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 888–896.Original Russian Text Copyright © 2004 by Larionov, Myachina, Saveleva, Glinskaya, Klevtsova, Sheludyakova, Tkachev, Bizyaev.     

Uranyl Methacrylate Complexes with Carbamide and Methylcarbamide: Synthesis and Structure

The synthesis and X-ray diffraction and IR spectroscopic study of (UO₂)₂(mac)₄(L)₃ · H₂O crystals, where mac^– is the methacrylate ion C₃H₅COO^– and L is carbamide (I) or methylcarbamide (II), have been performed. Complexes I and II have a homotypic structure: crystals contain two kinds of mononuclear uranium-containing complexes, i.e., cationic [UO₂(mac)(L)₃]⁺ and anionic [UO₂(mac)₃]^–. The crystallographic formula of complexes in structures I and II is AB⁰¹M ₃ ¹ + AB ₃ ⁰¹ (A =UO₂²⁺ B⁰¹ = mac^–, M¹ = L). The uranium-containing complexes in structures I and II are linked into a framework by means of electrostatic interactions and a system of hydrogen bonds. Despite the similar compositions and structures of the uranium-containing complexes, their packings into a three-dimensional framework appreciably differ from each other.     

Crystal Structure of 4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Triaquachlorolithium Dichloride

The crystal adduct (1 :1) 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane triaquachlorolithium dichloride, [H₂(Crypt-222)]²⁺ · 2Cl^– · [LiCl(H₂O)₃] (I), was synthesized and studied using X-ray diffraction analysis. Structure I (space group R3, a = 7.922 Å, c = 37.207 Å, Z = 3) was solved by direct methods and anisotropically refined by the full-matrix least-squares method to R = 0.034 for 1363 independent reflections (CAD4 autodiffractometer, MoK ). Crystal I consists of disordered 2.2.2-cryptand dications, chloride anions, and tetrahedral [LiCl(H₂O)₃] complexes. All of them lie on threefold axes. There are tridentate ⁺N–H (···O)₃ hydrogen bonds in the [H₂(Crypt-222)]²⁺ dication. The crystal structure of adduct I contains a complex interionic hydrogen bonding system.     

Two heterometallic complexes with a new macrocyclic oxamido complex ligand

A new macrocyclic oxamido-nickle(II) complex Na₂NiL was synthesized. L denotes the doubly deprotonated forms of (13Z, 19Z)-16-methyl-6,7-dioxo-5,6,7,8-tetrahydrotriben-zo[b,f,l][1,4,8,11]tetraazacyclotetradecine- 13,20-dicarboxylate. Based on the complex ligand Ni(L^2–), two heterometallic complexes [Ca₂(NiL)₂(H₂O)₈] · 10H₂O (I) and [Co(NiL)₂(H₂O)₂][Co(H₂O)₆] · 2.8H₂O (^II) were prepared. X-ray single crystal analyses (CCDC nos. 914618 (^I), 914616 (^II)) revealed that [Ca₂(NiL)₂(H₂O)₈] in I is a molecular box and the trinuclear complex anion [Co(NiL)₂(H₂O)₂]^2–in II is centrosymmetric. Thermogravimetric analyses showed that I exhibited moderately good stability and Co(II) catalyzed the thermal decomposition of II.     

Preparation,characterization and antifungal properties of transition metal ion complexes of quadridentate N3S ligands

Summary New metal complexes [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; NNNS^– = anion of the quadridentate ligands formed from S-methyl--N-(2-aminophenyl)-methylenedithiocarbazate and pyridine-2-aldehyde or 6-methylpyridine-2-aldehyde; X = Cl, NCS, NO₃ or I) and [Co(NNNS)Cl₂]·2H₂O have been prepared and characterized by elemental analysis and conductance measurements. Magnetic and spectroscopic evidence support a five-coordinate structure for [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; X = Cl, NCS) and a squareplanar structure for [Ni(NNNS)]X (X = NO₃ or I). The [Co(NNNS)Cl₃]·2H₂O complex is low-spin and octahedral. The Schiff bases and some of their metal complexes were tested against three pathogenic fungi, Alternaria alternata, Curvularia geniculata and Fusarium palidoroseum. The metal complexes are less fungitoxic than the free ligands.     

Nickel(II) Diisobutyldithiophosphinate Complexes with Hexamethylenetetramine and Triethylenediamine: Synthesis and Properties. Crystal and Molecular Structure of [Ni2(C6H12N4){(i-C4H9)2PS2}4]

The paramagnetic compounds [Ni₂(HMTA)(i-Bu₂PS₂)₄] (I) and [Ni₂(TEDA)(i-Bu₂PS₂)₄] (II) (_eff = 3.11 and 3.23 _B, respectively) were synthesized by reacting diamagnetic Ni(i-Bu₂PS₂)₂ with hexamethylenetetramine (HMTA) and triethylenediamine (TEDA) in ethanol. The crystal structure of I was established by single-crystal X-ray diffraction analysis (CAD4 diffractometer, MoK radiation, 1483 F _hkl, R = 0.0648). The crystals are monoclinic: a = 35.212(7) Å, b = 9.313(2) Å, c = 22.622(5) Å; = 129.97(3)°, V = 5685(2) ų, Z = 4, (calcd) = 1.281 g/cm³, space group C2/c. The structure is built of discrete binuclear molecules. The coordination polyhedron of the Ni atom is a distorted tetragonal pyramid with four S atoms of two bidentate cyclic ligands i-Bu₂PS₂ ^– in the base and the N atom of the bidentate bridging ligand HMTA at the axial vertex. Complexes I and II have similar electronic reflection spectra, which agrees with the C _4v symmetry of the ligand field.     

Crystal Structures,Cytotoxicity, Cell Apoptosis Mechanism,and DNA Binding of Two 8-Hydroxylquinoline Zinc(II) Complexes

Two zinc(II) complexes, [Zn₄(HOQ)₆Ac₂] (I) (HOQ = 8-hydroxylquinoline) and [Zn₄(MeQ)₆Ac₂] (II) (MeQ = 2-methyl-8-hydroxylquinoline), were synthesized and characterized by IR spectroscopy, ESI-MS spectrometry, elemental analysis and single crystal X-ray diffraction analysis (CIF files CCDC nos. 1433544 (I) and 1433546 (II)). The in vitro cytotoxicity of the two complexes, which was first reported, was evaluated by MTT assay against a series of tumor cell lines as well as HL-7702 normal liver cell line. The results indicated that they showed significantly higher cytotoxicity than cispltain on BEL-7404 cells with IC₅₀ values of 11.85 ± 0.06 μM (I) and 8.40 ± 0.07 μM (II), respectively. Further apoptosis mechanism studies on BEL-7404 cells suggested that their antitumor activities were achieved through cell apoptosis and arrest at G1 or S phase. The decline of mitochondrial membrane potential, the elevation of reactive oxygen species and cytoplasmic calcium concentration ([Ca²⁺]_c), the raise of caspase-3/9 activity indicated that complexes I and II induced apoptosis of BEL-7404 by a mitochondrial dysfunction pathway. Investigations on the binding properties of complexes I and II to ct-DNA by UV-Vis, circular dichroism spectra and agarose gel electrophoresis indicated that the two complexes could bind with ct-DNA via an intercalative mode.     

Copper(II) complexes of mono-condensed N,O-donor Schiff base ligands: Synthesis,crystal structures,and antibacterial activity

Two new copper(II) complexes, [Cu(L¹)₂] (I) and [Cu(L²)₂] (II), where L¹ = 2-bromo-4-chloro- 6-(isopropyliminomethyl)phenolate and L² = 2-bromo-4-chloro-6-[(2-hydroxyethylimino)methyl]phenolate, have been prepared and structurally characterized by X-ray crystallography (CIF files CCDC nos. 1445936 (I) and 1445935 (II)). In both complexes, the Cu atoms are coordinated by two phenolate oxygen and two imino nitrogen, giving square planar geometry. The complexes have been tested on various strains of bacteria to study their antibacterial effects.