Adenine complexes with divalent 3d metal chlorides

Upon refluxing 2:1 mixtures of adenine (adH) and divalent 3d metal chloride hydrates in a 7:3 (v/v) mixture of ethanol-triethyl orthoformate for several days, partial substitution of ad^? for Cl^? ligands occurs, and solid complexes of the M(ad)Cl· 2H₂0 (M = Mn, Zn), Fe₂(ad)(adH)₂Cl₃·2H₂O, M(ad)- (adH)Cl·H₂O (M = Co, Cu) and Ni₂(ad)₃Cl·6H₂O types are eventually isolated [1]. It is probably of interest that during analogous previous synthetic work, involving interaction of ligand and salt in refluxing ethanol, no substitution reactions between Cl^? and ad^? took place, and MCl₂ adducts with neutral adH were reportedly obtained. Characterization studies suggest that the new complexes reported are linear chainlike polymeric species, involving single adenine bridges between adjacent M²⁺ ions. Terminal chloro, adenine and aqua ligands complete the coordination around each metal ion. The new Ni²⁺ complex is hexacoordinated, whilst the rest of the complexes are pentacoordinated. Most likely binding sites are considered to be N(9) for terminal unidentate and N(7), N(9) for bridging bidentate adenine [1].     

The synthesis and characterization of nucleotide complexes involving an asymmetric metal

The synthesis of cobalt and chromium complexes of H₄ATP and H₄GTP in which the metal is asymmetric are reported. These compounds were characterized by visible spectroscopy, fast atom bombardment mass spectroscopy (FAB MS), and ³¹P NMR. The mass spectral data allow identification of the complexes to be made from ions in the molecular weight region. The effect of an asymmetric metal greatly alters the appearance of the ³¹P NMR spectra in comparison to complexes which do not have this feature. Complexes of uridine diphosphoglucose, UDPG, are also reported. The effect of an asymmetric metal ion on the chromatographic and spectral properties of the complexes are discussed.     

Synthesis and antitumor activity of platinum complexes of protonated diamines

Complexes of the formula cis-[Pt(H$\text{N}\text{+}$^～N)(L)Cl₂], where (H$\text{N}\text{+}$^～N) are the protonated diamines including 3-aminoquinuclidine, N-aminopiperidine, piperazine, N-methylpiperazine, 1,1,4-trimethylpiperazine, and N-methyl-1,4-diazabicyclo [2,2,2] octane (N-methyl-dabco) and L = SCN^?, NO₂^?, Br^?, and F^?, were synthesized from the protonated diamine complexes, [Pt(H$\text{N}\text{+}$^～N)Cl₃]. The antitumor activities of the complexes were evaluated in vitro against L1210 murine leukemia cells, and ID₅₀ values for the L-substituted complexes were compared to values of the parent complexes. In each case it was found that replacement of a chloride ion by SCN^?, NO₂^?, Br^?, or F^?, either reduced or completely eliminated antitumor activity. This effect is explained in terms of the trans-directing ability of the ligand, L, compared to chloride. The NO₂-substituted complex of 3- aminoquinuclidine was tested in vivo and found to exhibit little or no antitumor activity.     

Antitumor activity and metal complexes of the first transition series. Trans-bis(salicylaldoximato)copper(II) and related copper(II) complexes,a novel group of potential antitumor agents

The antitumor activity of forty nine different metal complexes of the first transition series against mouse leukemia L 1210 cells and of two of the complexes against Ehrlich ascites carcinoma have been tested in vitro by the method described in this paper. Eight complexes showed a 50% inhibition of tumor cell division at concentration level 5–6 μg/ml of the complex for the former and two most effective complexes also for the latter. The trans-bis-(salicylaldoximato)copper(II) and trans-bis(resorcylaldoximato)copper(II) complexes were found to possess the highest antitumor activity.     

Novel spectral-kinetic methods for investigation of ligand exchange in labile metal complexes in solutions

The luminescent spectral-kinetic method using selective complex excitation with short light pulse compared to relaxation reactions is described. The method makes it possible to obtain direct information on the rates of fast chemical reactions of dissociation or addition of ligands to Ln³⁺ ions in solutions. Data are presented on the rates and mechanisms of dissociation reactions for phenanthroline, bipyridile, salicylate, acetate, naphthoate and other complexes of Ln³⁺ ions in water and alcohols.     

Group IIB metal chloride complexes with some 2-(methylpyridyl or -quinolyl)benz-X-azoles

The complexes formed by Zn(II), Cd(II) and Hg(II) chlorides with benzimidazole, benzoxazole and benzothiazole linked to 4-methylpyridine and 4-methylquinoline have been prepared and characterized by chemical analysis, infrared spectra and conductivity data.The coordination behaviour of these ligands toward the metal salts and the stereochemistry of the obtained complexes have been investigated.     

Stability constants for,and structural investigation of,divalent metal ion complexes with polyene antibiotics

The stability constants for the formation of complexes between Ca(II), Mg(II), Cu(II), Zn(II) and Ni(II) with nystatin and amphotericin-B (polyene antibiotics) have been determined by both a potentiometric and a solubility method. The structures of the complexes have been investigated by NMR, ESR and CD spectroscopy. The transition metal stability constants are consistent with the Irving- Williams series. The structural results are discussed and related to the importance of such complexes in mode of action theories.     

Optically active transition metal complexes. 87. Synthesis of porphyrin complexes containing chiral Fe atoms. Demonstration of Fe chirality by 1H NMR spectroscopy

After transformation of the vinyl groups in hemin into H, CH₂CH₃ and COCH₃, the propionic acid side chains were converted into esters and amides using (-)-menthol, (-)-2-methylbutanol and (-)-1-phenylethylamine. By introducing the CS ligand into the apical position, square pyramidal complexes were obtained, differing only in the Fe configuration, which could not be separated. However, the two diastereomers with different Fe configuration, having optically active 1-phenylethylisonitrile and pyridine (or 4-methylpyridine) as ligands in the axial positions, at ?20°C exhibit different chemical shifts demonstrating configurational stability at the Fe atom on the ¹H NMR time scale. At room temperature epimerization at the Fe atom occurs by ligand exchange reactions.     

Metal ion-purine interactions: Preparation and study of some metal complexes of 8-ethyl-xanthine and 8-ethyl-3-methyl-xanthine

The interactions of 8-ethyl-xanthine (8EH) and 8-ethyl-3-methylxanthine (3MEH) with Cu(II), Pd(II), Ag(I) and Au(III) ions in aqueous medium were studied, and the isolated complexes characterized by means of ¹H NMR and IR as well as elemental analyses. Reactions occur over a wide pH range, with the purine bases acting as a monoanion, in molecular or protonated forms.     

Transition metal nitrosyls as nitrosylation agents. IV. 51V NMR characteristics of dinitrosyl and carbonylmononitrosyl vanadium complexes

The action of [Co(X)(NO)₂]₂ (X = Cl, Br, L) on [V(H)(CO)_6?nL_n] (L = 1/ndi- and tritertiary phosphine; n = 2, 3) in thf yields [V(CO)_5?n(NO)L₂] and [V(NO)₂(thf)₄]X as the two main products. Thf is easilty replaced by other ligands L′, leading to the complexes cis-[V(NO)₂(thf)_4?nL′_n]X, where n = 1 to 4. In the case of L′= CNR (R = Cy, iPr, tBu), the species [VX(NO)₂L′₃] are formed. The presence of X in the first coordination sphere is established by the normal halogen dependence (Cl < Br < I) of ⁵¹V shielding.δ(⁵¹V) values have been obtained for the two series of complexes and compared with δ of other nitrosylvanadium species, including [VX(NO)L′₄]X. for [V(NO)₂L′₄]br, ⁵¹V shielding increases in the sequence {O} < {S} < NR₃ < NCMe < AsEt₃ < SbEt₃ < PEt₂Ph < P(OMe)₃ < CNR, reflecting a general increase of shielding as the polarizability of the ligand function increases and its electronegativity decreases. Superimposed effects arising from electronic influences (PEtPh₂) < PMe₃ < P(OMe)₃ and steric conditions (chelate-4 ring < 7 ring < 6 ring < 5 ring) are also discussed. Steric factors are especially pronounced in the [V(CO)₃(NO)Ph₂P(CH₂)_mPPh₃] series (m = 1–4). The thermo-labile parent compound, [V(CO)₅NO], has been characterized by its δ(⁵¹V) = ?1489 ppm at 245 K.     

Microcalorimetric evaluation of the biological activity of polyene complexes with divalent metal ions: Mg(II), Ca(II), Ni(II), Cu(II) and Zn(II)

Polyene complexes with Mg(II), Ca(II), Ni(II), Cu(II) and Zn(II) have been prepared and evaluated for biological activity in a flow microcalorimetric study. The bioactivities are all lower per g of complex than is the bioactivity of the patent polyene, nystatin. However extrapolation of the linear bioassay data suggests that because of enhanced solubilities the metal ion complexes may be able to yield higher overall bioactivity than can nystatin alone.     

Chromium(III) complexes and their relationship to the glucose tolerance factor. Part II. Structure and biological activity of amino acid complexes

A number of octahedral chromium complexes with amino acids are ligands have been prepared and their structures assigned on the basis of their chromatographic and spectral properties. These include complexes with the general structure Cr(AA)₂(H₂O)₂ where the amino acids glycine, glutamic acid and glutamine act as bidentate ligands. The analogous compound with cysteine as ligand is stable at low pH, but at high pH a terdentate cysteine complex, Cr(cysteine)₂^?, is formed. These complexes, as well as a solution of monodentate glycine aquo complexes, and Cr-nicotinic acid-glycine and Cr-nicotinic acid-cysteine complexes of undetermined structure, have been assayed for glucose tolerance factor activity using a yeast assay. Only Cr(glutamine)₂- (H₂O)₂⁺, Cr-nicotinic acid-glycine and the mixture of complexes Cr(glycine)_n(H₂O)_6-n⁺³ showed significant activity. It is proposed that a trans arrangement of the non-coordinated nitrogen atoms in the ligands of these complexes can mimic the structural features of the glucose tolerance factor which are essential for biological activity.     

Synthesis,FT-IR and 1H NMR studies of alkali and alkaline earth metal complexes with guanosine

The synthesis of complexes of Li(I), K(I), Mg(II), Ca(II) and Ba(II) with guanosine in basic non aqueous solutions is described. The complexes were of two types: (1) complexes having the general formula, M(Guo)_nX_m·YH₂O·ZC₂H₅OH, where M = Mg(II), Ca(II), Ba(II) and Li(I), n = 1,2,4, X = Cl^?, Br^?, NO₃^?, ClO₄^? and OH^?, m = 1,2, Y = 0?6 and X = 0?2, and (2) complexes with the general formula, M(GuoH-1)(OH)_n^?1·YH₂O, where M = K(I), Ca(Il) and Ba(II), GuoH-1 =Ionized guanosine at N₁, n = 1,2 and Y = 1?3. The complexes are characterized by their proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FT-IR) spectra. The FT-IR and ¹H NMR data of the non ionized nucleoside complexes suggest that the metal binding is through the N₇-site of guanine and that the anion (X) is hydrogen bonded to N₁H and NH₂ groups. In the N₁-ionized guanosine complexes the metal binding is via the O₆^? of guanine. All the complexes formed exhibited a transition of the sugar conformation from C₂′-endo/anti in the free nucleoside to C₃′-endo/anti in the metal complexes.     

Metal(II) complexes of 1-formylisoquinoline thiosemicarbazone: their preparation,characterization and antitumour activity

Complexes of Co(II), Ni(lI), Cu(II), Zn(II) and Pt(II) with 1-formylisoquinoline thiosemicarbazone (1-iqtsc-H) were prepared and characterized by elemental analyses, conductance measurement and spectral studies. On the basis of these studies a distorted octahedral structure for [Co(1-iqtsc)₂]·2H₂O, a distorted trigonal-bipyramidal structure for [Ni- (1-iqtsc-H)Cl₂], [Cu(1-iqtsc-H)Cl₂] and [Zn(1-iqtsc- H)(OAc)₂]·H₂O and a square-planar structure for [Pt(1-iqtsc)Cl] are suggested. All these metal(II) complexes were screened for their antitumour activity in the P388 lymphocytic leukaemia test system in mice. Except for Pt(Il), the complexes were found to possess significant activity; the Ni(II) complex showed a T/C value of 161 at the optimum dosage.     

Schiff-base complexes of dimethyldichlorosilane

Several Schiff-bases obtained by the condensation of monoamine or diamine with substituted benzaldehyde were synthesized and then coordinated with dimethyldichlorosilane. The products of reaction were characterized by elemental analyses, conductivity measurements, and infrared and nuclear magnetic resonance spectroscopic data. A majority of the complexes exhibit a 1:1 (silicon: Schiff-base) stoichiometry and a few have 1:2 stoichiometry.     

Dicopper complexes of polyethyleneimine and polyvinylamine vinylsulfonate

Binuclear copper(II) complexes prepared with the binucleating ligand 2,6-diformyl-4-methyl-phenol were attached as pendant groups to the polymers polyethyleneimine and polyvinylaminevinyl sulfonate sodium salt. The polymer-copper(II) complexes were characterized from optical and magnetic studies and their catecholase activities were measured in water. Polyvinylamine-vinylsulfonate-copper(II) is insoluble in water and showed little if any catecholase activity. The polyethyleneimine-copper complexes were reasonably soluble in water and demonstrated good catecholase activity. The catecholase activity of the polyethyleneimine-copper complexes increased in activity with an increase in the ratio of polymer-to-copper content (based on a constant copper concentration).