John D. Ranford

Thermal Conversion of a Helical Coil into a Three-Dimensional Chiral Framework.

Thermal dehydration results in the solid-state supramolecular conversion of the helical coordination polymer [{[Cu(sala)](2)(H(2)O)}(n)] into the chiral three-dimensional covalent open network [{Cu(sala)}(n)] (shown schematically). X-ray crystallography reveals that hydrogen bonding plays a key role in this process. H(2)sala=N-(2-hydroxybenzyl)-L-alanine

Antitumour copper(II) salicylaldehyde benzoylhydrazone (H2sb) complexes: physicochemical properties and the single-crystal X-ray structures of [{Cu(H2sb)(CCl3CO2)2}2] and [{Cu(Hsb) (ClO4) (C2H5OH)}2] and the related salicylaldehyde acetylhydrazone (H2sa) complex, [Cu(Hsa)Cl(H2O)]·h2O

Copper(II) complexes of the antitumour ligand salicylaldehyde benzoylhydrazone (H2sb) have been prepared. In the presence of strong acids, complexes of the neutral ligand were isolated: [{Cu(H2sb)X2}2]·nH2O (X = Br, n X = CCl3CO2, n = 0) and [Cu(H2sb)Cl2(H2O)]. In weakly acid or neutral media, monoanionic compounds separated: Cu(HsB)X2·nH2O] (X = Cl,Br, NO3, 0.3SO4, n = 0; X = ClO4, n = 1). With base only the highly insoluble dianionic complex [{Cu(sb)}2] was isolated. Also prepared was the related anionic ligand complex [Cu(Hsa)Cl(H2O)]·H2O (H2sa = salicylaldehyde acetylhydrazone). The complexes have been characterised by a range of physicochemical techniques and the crystal and molecular structures of [{Cu(H2sb)(CCl3CO2)2}2], [{Cu(Hsb)ClO4(C2H5OH)}2] and [Cu(Hsa)Cl(H2O)]·H2O, determined by single-crystal X-ray diffraction studies. Crystals [{Cu(H2sb)(CCl3CO2)2}2] are triclinic, space group , with = 10.130(2), b = 11.660(2), c = 11.876(2)r α = 67.07(2), β = 109-09(2)γ = 107.84(2)° and Z = 2. The complex is a centrosymmetric dimer, the monomeric units being bridged through the phenol oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate ‘ONO’ donor ligand and the symmetry-related phenol oxygen. The more weakly bound axial donor oxygens are from the coordinated trichloroacetates. Crystals of [Cu(Hsb)ClO4(C2H5OH)2] are monoclinic, space group P21/c, with a = 11.2281(8), b = 7.9129(4), c = 21.043(1) ;rA β = 98.560(6)°✓ and Z = 4. This complex is also a centrosymmetric dimer, the monomeric units being bridged through the phenoxy oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate ‘ONO’ ligand and the symmetry related phenoxy oxygen. The more weakly bound axial donor oxygens are supplied by the ethanol and perchlorato moieties. Crystals of [Cu(Hsa)Cl(H2O)]·H2O are monoclinic, space group P21/c, with . The complex is monomeric with the copper(II) adopting a square-pyramidal coordination. The four in-plane donors are provided by the tridentate ‘ONO’ donor Hsa and an oxygen from a coordinated water molecule; the axial site is occupied by the chloride ion. Most of the complexes have low magnetic moments and are assigned dimeric side-by-side structures. Powder ESR spectra have g1 and g✓ resolved often with ΔM = 2 transitions present.

Topochemical Conversion of a Hydrogen-Bonded Three-Dimensional Network into a Covalently Bonded Framework

Thermal dehydration promotes the topochemical conversion of the hydrogen-bonded dimeric complex [{Zn(sala)(H2 O)2 }2 ]⋅2 H2 O (H2 (sala)=N-(2-hydroxybenzyl)-L-alanine) to generate covalent [{Zn(sala)}n ]. X-ray crystallography reveals that hydrogen bonding plays a key role in this process (see the partial structure on the right).

Copper(II) complexes of the antitumour-related ligand salicylaldehyde acetylhydrazone (H2L) and the single-crystal X-ray structures of [{Cu(HL)H2O}2] · 2(NO3) and [{Cu(HL) (pyridine) (NO3)}2]

Binary and ternary copper(II) complexes of the ligand salicylaldehyde acetylhydrazone (H2L) have been prepared. In acid or neutral media monoanionic HL complexes separate. Addition of the Lewis bases pyridine (py) and thiourea (tu) to [{Cu(HL)H2O}2] · 2(NO3) results in the monoanionic ternary ligand adducts [{Cu(HL) (py) (NO3)}2] and [Cu(HL) (tu) (NO3)], respectively. With base, the le soluble dianionic complex [{CuL}2] was isolated. Addition of py to [{CuL}2]afforded the dianionic ternary complex [CuL(py)]·12H2O. The complexes have been characterized by a range of physicochemical techniques and the crystal and molecular structures of [{Cu(HL)H2O}2] · 2(NO3) and [{Cu(HL) (py) (NO3)}2] determined. Crystals of [{Cu(HL)H2O}2] · 2 (NO3), C18H22Cu2N6O12, are monoclinic, with space group P21/c, a=7.217(4), b=11.758(8), c=13.764(8) A, β=95.47(4)° and Z=4. [{Cu(HL)H2O}2] · 2 (NO3) is a centrosymmetric (planar) dimer, the monomeric units being bridged through the phenoxy oxygen. The copper atom has a square-pyramidal geometry with the basal donor atoms coming from the tridentate ligand (ONO) and the symmetry-related phenolate (O). The more weakly bound apical donor oxygen is supplied by a coordinated water molecule. The nitrate is not bound. Crystals of [{Cu(HL)(py) (NO3)}2], C28H28Cu2N8O10, are monoclinic, with space group P21/c, a=10.642(3), b=11.796(3), c=13.137(2) A, β=111.03(2)° and Z=4. [{Cu(HL) (py) (NO3)}2] is a weakly interacting centrosymmetric (stacked) dimer, the monomeric units being bridged axially through the phenoxy oxygen. The copper atom has a tetragonal geometry with the equatorial donor atoms coming from the tridentate ligand (ONO) and the pyridine (N). The more weakly bound nitrato anion provides the other axial donor (O). Several of the complexes exhibit interesting magnetic properties.

COMPLEXES OF SALICYLALDEHYDE ACYLHYDRAZONES : CYTOTOXICITY, QSAR AND CRYSTAL STRUCTURE OF THE STERICALLY HINDERED T-BUTYL DIMER

A series of acylhydrazones of salicylaldehyde and their transition metal complexes, predominantly copper(II), have been prepared and characterized. The crystal structure of the Cu(II) complex of the sterically hindered t-butyl derivative contains a phenolato bridged dimer with the ligand coordinated as a tridentate moiety. QSAR analyses of the cytotoxicity of the chelators and their Cu(II) complexes reveals that solubility is the dominant factor for activity. Compounds display a maximum with respect to lipophilicity, allowing optimization of the bioactivity for both the ligands and their complexes. Copper complexes are significantly more cytotoxic than the metal-free ligands and complexes of other metals: Cu > Ni > Zn = Mn > Fe = Cr > Cr > Co.

Hexafluorosilicate coordination to the antitumour copper(II) salicylaldehyde benzoylhydrazone (H2L) system: single-crystal X-ray structure of [{Cu(HL)H2O}2SiF6]·2H2O

The complex [{Cu(HL)H2O}2SiF6]·2H2O (H2L = salicylaldehyde benzoylhydrazone) has been prepared from the reaction of CuF2·2H2O in concentrated HF with ethanolic solution of H2L. SiF62− was generated by the in situ reaction of fluoride on silica. The complex has been characterized by a range of physicochemical techniques and the crystal and molecular structure determined by single-crystal X-ray diffraction. The crystals of [{Cu(HL)H2O}2SiF6]·2H2O are monocliic, space group C2/c, with a = 13.677(5), b = 11.876(3), c = 20.3 A, β = 105.92(3)° and Z = 4. The complex is a discrete centrosymmetric dimer, the monomeric units being bridged by the coordinated SiF6 2− anion with the Si lying on the inversion centre. The copper atom has a distorted square-pyramidal geometry with three donor atoms (ONO) from the tridentate monoanionic HL− ligand and the fourth in-plane donor (O), from a water molecule. The fifth position is occupied by a less strongly bound fluorine from the bridging SiF62− anion. Alternate stacking of the dimeric units which would allow overlap of π electron density as well as H bonding involving all of the hexafluorosilicato F atoms appears to be important for the stability of the complex in the solid.

Complexes of platinum(II) or palladium(II) with 1,10-phenanthroline and amino acids

The amino acids complexes of [Pt(phen)(AA)]NO3·xH2O and [Pd(phen)(AA)]NO3·xH2O have been prepared by the interaction of palladium and platinum complexes, [Pt(phen)Cl2] and [Pd(phen)Cl2] with salts of amino acids in methanol and characterized by 1H NMR and IR spectroscopy which confirmed the formation of a very large variety of compounds with ligand in a simple way (bidentate). All of these new compounds have been isolated and tested for cytotoxicity on Molt-4, a human leukaemia cell line. The IC50 values of [Pt(phen)(Pro)]Cl·2H2O and [Pd(phen)(Asp)]Cl·1.5H2O are 9.8 and 7.31 μM, respectively, exhibiting a significant activity which is close to cis-[PtCl2(NH3)2].

Synthesis, characterization and physicochemical properties of copper(II) complexes containing salicylaldehyde semicarbazone

Abstract Copper(II) complexes containing a series of salicylaldehyde semicarbazone ligands have been prepared and characterized by a range of physicochemical techniques. The X-ray structure of [Cu(HBnz2)Cl]·H2O (5) (where HBnz2 is salicylaldehyde-N,N-dibenzyl semicarbazone) shows the complex is monomeric and the copper atom is four coordinated in a distorted square planar geometry. The ligand chelates the copper in a tridentate fashion through the imine N, carbonyl O and phenolato O with the fourth position being occupied by coordinated Cl. The compound [Cu(Ph2)·H2O] (4) (where Ph2 is salicylaldehyde-N,N-diphenyl semicarbazone) is also formulated as a monomer whereas all other complexes are assumed to have a side-by-side dimeric arrangement of the metal chelating with the phenolate bridging the Cu(II) centres.

Chemical and biological studies of the dichloro(2-phenylpyridine) gold(III) complex and its derivatives

Four new derivatives of the type [Au(ppy)X2] (ppy = 2-phenylpyridine) together with [Au(ppy)Cl2] (1) have been synthesized and characterized [X = ac = CH3COO− (2), bz = C6H5COO− (3); mal = CH2(COO−)2 (4), cbdca = C4H6(COO−)2 (5)]. The crystal structures of 2 and 3 are similar in which two carboxylate groups are bound to gold through oxygen, but the two Au–O distances are inequivalent. The crystal structure of 5 shows that gold is bound to σ-C,N-phenylpyridine (ppy) and O,O-cbdca, forming a five-membered and a six-membered chelate ring, respectively. In all four structures the Au(III) center exhibits a square planar coordination geometry and the trans influence of the σ-bonded phenyl group is apparent. The σ-bonded phenyl group contributes to stabilizing these complexes in reducing, biological media. The reaction between 5 and chloride has been investigated by 1H NMR spectroscopy and reveals slow replacement of cbdca by chlorides through an intermediate [Au(ppy)(O-cbdca)Cl]. All five complexes have been tested for cytotoxic properties in vitro against MOLT-4 (human leukemia) and C2C12 (mouse tumour) cell lines. The results show that these complexes have similar cytotoxicity profile to cisplatin against MOLT-4 but are inactive on C2C12, except for complex 5.

Gold(III) thiosalicylate complexes containing cycloaurated 2-arylpyridine, 2-anilinopyridine and 2-benzylpyridine ligands

Reactions of the gold(III) dichloride complexes [(N_C)AuCl 2 ] ((N_C)=cycloaurated 2-phenylpyridine, 2-( p -tolyl)pyridine, 2-anilinopyridine or 2-benzylpyridine) with thiosalicylic acid (2-mercaptobenzoic acid, HSC 6 H 4 CO 2 H) and base gives a series of gold(III) thiosalicylate complexes [(N_C)Au(SC 6 H 4 CO 2 )]. A crystal structure determination on the 2- p -tolylpyridine derivative is reported, confirming the presence of a chelating thiosalicylate ligand, with the tolyl and thiolate groups mutually cis , together with a highly puckered gold–thiosalicylate moiety, and a twisted carboxylate group. The activity of the thiosalicylate complexes against P388 leukaemia cells has been determined.