Sonia B. Jiménez-Pulido

Chloro-fac-tricarbonylrhenium(I) complexes of asymmetric azines derived from 6-acetyl-1,3,7-trimethylpteridine-2,4(1H,3H)-dione with hydrazine and aromatic aldehydes: preparation, structural characterization and biological activity against several human tumor cell lines.

A number of new asymmetric azines derived from hydrazine and 6-acetyl-1,3,7-trimethyllumazine (lumazine=pteridine-2,4(1H,3H)-dione) and its derivatives with several aromatic aldehydes have been prepared and characterized by usual procedures (XRD, IR, (1)H and (13)C NMR). These were reacted with [ReCl(CO)(5)] to give the corresponding mononuclear chloro-fac-tricarbonylrhenium(I) [ReCl(CO)(3)L] compounds. The complexes were characterized by elemental analysis, thermogravimetry (TG) and differential scanning calorimetry (DSC), IR, (1)H and (13)C NMR. Furthermore, single-crystal X-ray diffraction studies have also allowed to report two different coordination modes of the ligands, which are strongly influenced by the basicity of the heteroatoms on the aromatic aldehyde; thus, the hydrazones derived from hydrazine and hydroxyaldehydes are linked to Re(I) through N5 atom from the pyrazine ring and the N61 one from the hydrazino group, whereas with the ligand derived from pyridin-2-carbaldehyde, the N62 atom of the hydrazino group and the N1 from the pyridine moiety are preferred ligand-to-metal binding sites. The study of the effects of the compounds on the growth of four human tumor cell lines (neuroblastoma NB69, glioma U373, and breast cancer MCF-7 and EVSA-T) suggests a modulator behaviour, according to the concentration, of cell growth due to their estrogen-like characteristics.

Metal complexes with the ligand derived from 6-acetyl-1,3,7-trimethyllumazine and benzohydrazide. Molecular structures of two new Co(II) and Rh(III) complexes and analysis of in vitro antitumor activity.

The structures and spectroscopic properties of new Mn(II), Co(II), Cd(II), Hg(II), Ag(I), Rh(III), and Ir(I) complexes with the ligand BZLMH derived from 6-acetyl-1,3,7-trimethyllumazine (lumazine=pteridine-2,4(1H,3H)-dione) and benzohydrazide are reported. Complexes have been characterized by elemental analyses, spectroscopic studies (IR, UV-vis, (1)H, (13)C and (15)N NMR) and magnetic measurements. In all the complexes, the lumazine-derived ligand appears to be coordinated in either tridentate (N5, N61 and O63) or tetradentate forms (O4, N5, N61 and O63). The molecular structures of the [Co(BZLMH)(H(2)O)(CH(3)CN)(2)](ClO(4))(2) x CH(3)CN and [RhCl(2)(BZLM)(CH(3)CN)] x CH(3)CN complexes, determined by single crystal X-ray diffraction, have allowed to corroborate both coordination behaviours. The cytotoxic activity of the free ligand and complexes against human neuroblastoma NB69 cell line is also described. The differential analysis of the initial cytotoxic screening data has shown good activity only for the [RhCl(2)(BZLM)(CH(3)CN)] x CH(3)CN compound at concentrations at around 2 microM; for the other complexes, a modulation of the cell growth was not found upon complexation, this non-specific effect strongly suggesting an apoptotic behaviour.

Synthesis and characterization of new complexes formed between 1-methyllumazine and 1,6,7-trimethyllumazine ligand with transition metal(II) nitrate. Crystal structure of cobalt(II), copper(II) and cadmium(II) complexes

Abstract The structures and spectroscopic properties of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) nitrate complexes of 1-methyllumazine (MLM) and 1,6,7-trimethyllumazine (MLMD) with general formula M(II)(NO 3 ) 2 L 2 · n H 2 O are reported. In all the complexes, the lumazine-derived ligands seem to be coordinated in bidentate form through the N5 and O4 atoms. The crystal structures of [Cu(MLM) 2 (H 2 O) 2 ](NO 3 ) 2 ( 1 ), [Co(MLMD) 2 (H 2 O) 2 ](NO 3 ) 2 ( 2 ) and [Cd(MLMD) 2 (NO 3 ) 2 ] ( 3 ) have been determined by X-ray crystallographic methods. In compounds 1 and 2 the nitrate anions are uncoordinated, and the metal ions are surrounded in an octahedral geometry by two bidentate lumazine ligands and two coordinated water molecules. The absolute configuration of the complex 1 can be described as the 4M stereoisomer, following Bailars nomenclature, with the two lumazine in a cis arrangement and the complex 2 exhibits the 2L stereoisomer as is usually in this kind of complexes. Compound 3 consists of neutral mononuclear units, the Cd(II) environment being a bicapped octahedral close to the trigonal antiprism due to the two nitrate anions coordinating in a very unsymmetrical bidentate mode.

Rhenium(I) coordinated lumazine and pterin derivatives: structure and spectroelectrochemistry of reversibly reducible (6-ATML)Re(CO)3Cl (6-ATML=6-acetyl-1,3,7-trimethyllumazine)

Abstract A number of complexes between substituted lumazines (2,4-dioxo-(1H,3H)pteridines) or pterins (2-amino-4-oxo-(3H)pteridines) and Re(CO)3Cl have been synthesized and characterized electrochemically and spectroscopically. The structure of the (6-ATML)Re(CO)3Cl derivative (6-ATML=6-acetyl-1,3,7-trimethyllumazine) could be determined in [fac-(6-ATML)Re(CO)3Cl]·3C6H6. The rhenium(I) center coordinates in a rather symmetrical fashion through the O4–N5 α-carbonylimino chelate site of 6-ATML; the potentially available acetyl function is not involved in the metal coordination. The acetyl acceptor substituent facilitates the reversible one-electron reduction of this compound to a persistent anion radical complex [(6-ATML)Re(CO)3Cl] −, which is accompanied by variable low-frequency shifts of the six carbonyl stretching bands and by the appearance of a broad EPR signal.

Synthesis and structural studies on metal nitrate complexes with 1,3-dimethyllumazine and 1,3,6,7-tetramethyllumazine: crystal structure of two new cobalt(II) and copper(II) three-dimensionally hydrogen-bonded complexes and a cadmium(II) complex with unusual geometry

Abstract In absolute methanol medium, M II (NO 3 ) 2 (M = Co,Ni,Cu,Zn and Cd) react with 1,3-dimethyllumazine (DLM) and 1,3,6,7-tetramethyllumazine (DLMD) (lumazine = (1 H ,3 H )-pteridin-2,4-dione) to give complexes with general formula M II (NO 3 ) 2 (pteridine) 2 · n H 2 O. These compounds have been characterized by means of the analytical techniques (elemental analysis and thermogravimetry), spectral methods (IR, 13 C and 1 H NMR, UV-Vis-NIR, EPR) and magnetic measurements (77–290 K). Single-crystal X-ray diffraction studies have been made on the complexes [Co(DLM) 2 (H 2 O) 2 ](NO 3 ) 2 ·2H 2 O, [Cu(DLMD) 2 (H 2 O) 2 ](NO 3 ) 2 ·2H 2 O and [Cd(NO 3 ) 2 (DLMD) 2 ]. Cobalt and copper complexes crystallize in the monoclinic system (space group P 2 1 / n , Z = 2) with a = 8.746(1), b = 13.584(2), c = 10.997(1) A , β = 94.89(1)°, V = 1301.8(3) A 1 , and R = 0.057 for 3787 independent reflections with l >2 σ (1) and 202 parameters (Co/DLM complex) and a = 8.9929(7), b = 1.0574(9), c = 11.9242(7) A , β = 98.124(5)°, V = 1492.3(2) A 1 , and R = 0.039 for 2612 independent reflections with l >2 σ ( l ) and 230 parameters (Cu/DLMD complex). In both complexes, the metal ion occupies an inversion center and exhibits an octahedral coordination. The Co(II) coordination octahedron is tetragonally flattened, but the Cu(II) coordination is rhombically distorted. The equatorial plane consists of two N(5) and two O(4) atoms of pteridine ligands and the two axial sites are occupied by two oxygen atoms from the coordinated water molecules. The monomeric units together with non-coordinated water molecules and nitrate anions are involved in a complex three-dimensional H-bond network. The cadmium complex crystallizes in the monoclinic system (space group P 2 1 / c , Z = 2) with a = 8.5689(4), b = 18.5279(9), c = 8.6209(3) A , β = 106.894(3)°, V = 1309.6(1) A 3 , and R = 0.030 for 1260 independent reflections with l >2 σ ( l ) and 192 parameters. The structure consists of monomeric centrosymmetric units in which the cadmium atom is eight-coordinated by four nitrate oxygen atoms of two bidentate nitrate anions and two N(5)-O(4) lumazine bidentate ligands. The geometry of the coordination polyhedron could be described as an octahedron whose equatorial plane is formed by two bidentate N(5)-O(4) pteridine ligands and whose apical positions each seem to be split into two coordination positions occupied by bidentate nitrate ligands.

Versatile coordinative abilities of a new hybrid pteridine-thiosemicarbazone ligand: crystal structure, spectroscopic characterization, and luminescent properties.

The synthesis and characterization of the first thiosemicarbazone-lumazine (TSCLMH=the thiosemicarbazone of 6-acetyl-1,3,7-trimethyllumazine) hybrid ligand is reported. The influence of the conformation of this compound on its energy and the atomic contribution to the molecular orbitals have been theoretically investigated. Ni(II), Cu(I), Zn(II), and Cd(II) complexes of this ligand have been synthesized and characterized by elemental analysis, thermogravimetric studies, IR, 1H, 13C, and 15N NMR, and UV-vis-NIR spectroscopy, magnetic measurements, and X-ray crystallography. Four types of coordination modes for the ligand may be predicted: (a) double bidentate; (b) tetradentate; (c) tridentate; (d) bidentate. Structures of representative complexes of types a, b, and d have been determined by X-ray crystallography. In the [Cu(TSCLMH)]2(ClO4)2 complex, TSCLMH acts as a doubly bidentate bridging ligand forming a dimer with a Cu...Cu distance of 2.876 A. The geometry around the metal ion is trigonally distorted tetrahedral with a relatively long (four-atom) bridge between the metal centers instead of the shorter, mainly single atom, bridges present in other thiosemicarbazone derivatives complexes. In the [Cd(NO3)2(TSCLMH)(EtOH)] complex, the metal ion displays eight-coordinated geometry with the TSCLMH ligand acting in a tetradentate planar fashion and two nitrate anions, one monodentate and the other bidentate. The coordination polyhedron in [Cd(TSCLM)2(H2O)].MeOH.2H2O is a square pyramid with two monoanionic ligands acting as bidentate NS donors and a water molecule completing the coordination sphere. Fluorescence spectroscopic properties of TSCLMH have been studied as well as the changes in position and intensity of fluorescence bands caused by the complexation with different metal ions (Ni2+, Cu+, Zn2+, Cd2+).

Synthesis and characterization of several lumazine derivative complexes of Co(II), Ni(II), Cu(II), Cd(II), Pd(II) and Pt(II). X-ray structures of a mononuclear copper complex and a dinuclear cadmium complex

The synthesis of the new Co(II), Ni(II), Cu(II), Cd(II), Pd(II) and Pt(II) complexes with 1-methyllumazine (1-methylpteridine-2,4(1 H ,3 H )-dione, MLM) and 1,6,7-trymethyllumazine (1,6,7-trimethylpteridine-2,4(1 H ,3 H )-dione, MLMD) is described. The coordination chemistry of these ligands have been investigated and an usual bidentate bonding mode through the N5 and O4 atoms is observed. These complexes present the form M II Cl 2 L and were characterized by elemental analyses, TG and DSC, as well as by IR, UV–Vis, EPR spectroscopy and magnetic measurements. The crystal structures of [CuCl 2 (MLMD)(H 2 O)] and [CdCl 2 (MLM)(H 2 O)] 2 have been determined by X-ray diffraction methods. The copper(II) compound exists in the monomeric form with an environment around the metal ion as a distorted square-based pyramidal geometry whereas the cadmium complex was observed as dimers with an edge-sharing distorted octahedral coordination sphere around each cadmium center.

Spectral and XRD studies on perchlorate salts of several Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes from 1-methyllumazine and 1,6,7-trimethyllumazine

Abstract A number of complexes with general formula ML2(ClO4)2·nH2O·mCH3CN [M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)] have been synthesized by reaction of 1-methyllumazine (MLM) and 1,6,7-trimethyllumazine (MLMD) and perchlorate salts in acetonitrile. The complexes have been characterized by elemental analysis, TG and DSC, as well as by IR, UV–Vis, EPR spectroscopies and magnetic measurements. The crystal structures of [Cu(MLM)2(H2O)2](ClO4)2, [Zn(MLM)2(H2O)2](ClO4)2 and [Cu(MLM)(MLMD)(H2O)(CH3CN)](ClO4)2 have been determined by X-ray diffraction methods. In the complexes Cu/MLM and Zn/MLM, the metal ions involve an octahedral geometry with two water molecules and two lumazine ligands coordinated through O4 and N5 atoms. The compound Cu/MLM/MLMD consists of monomeric units in which the Cu(II) atom is linked by two different lumazine derivatives (MLM and MLMD), a water and an acetonitrile molecules bonding directly to the metal ion. The environment around metal ion exhibits a geometry between a square-based pyramidal and an elongated tetragonal octahedral due to the different distances CuO4 in the apical positions.

Synthesis and structural studies on three-dimensionally hydrogen-bonded metal perchlorate complexes with 1,3-dimethyllumazine and 1,3,6,7-tetramethyllumazine. Crystal structure of diaqua-bis(1,3,6,7-tetramethyl-pteridine2,4(1H,3H)-dione-O4,N5) copper(II) perchlorate dihydrate

Abstract In aqueous solution, M II (ClO 4 ) 2 (Mn  Mn, Co, Ni, Cu, Zn, Cd and Hg) reacted with 1.3-dimethyllumazine 9DLM) and 1,3,6,7-tetramethyllumazine (DLMD) (lumazine = (1 H ,3 H )-pteridin-2,4-dione) to give complexes with general formula Mp II (ClO 4 ) 2 (LM) 2 · n H 2 O. These compounds have been characterized by means of the analytical techniques (elemental analysis and thermogravimetry), spectral methods (IR, 13 C and 1 H NMR, UV-VIS-NIR, electron paramagnetic resonance) and magnetic measurements (77–290 K). Single-crystal X-ray diffraction studies have been made on the complex [Cu(DLMD) 2 (H 2 O) 2 ](ClO 4 ) 2 ·2H 2 O. This compound crystallizes in the monoclinic system. P 2 1 / c space group, Z = 2, with a = 8.764(1), b = 13.7932(8), c = 14.792(1) A , β = 116.02(1)°, V = 1602.9(3) A 3 , and R = 0.0728 for 4648 independent reflections and 224 parameters. The metal ion occupies an center and exhibits a distorted octahedral coordination. The coordination octahedron is flattened, the equatorial plane consisting of two N(5) and two O(4) atoms of pteridine ligands: the two axial sites are occupied by two oxygen atoms from the coordinated water molecules. The monomeric units together with non-coordinated water molecules and perchlorate anions are involved in a complex three-dimensional H-bonds network, the pteridine moieties being packed following planes roughly parallel to b axis, and perpendicular to the [5 4 21] direction. These planes are separated by a mean distance of 7.3 A.

Synthesis and structural studies on new MIIX2L2 dihalocomplexes of 1-methyllumazine and 1,6,7-trimethyllumazine.: Crystal structure of copper(II) and palladium(II) complexes

In order to continue our studies in coordination chemistry with pteridine derivatives, four new complexes with general formula M II X2(pteridine)2/n H2O/m CH3CN (M � /Cu, Pd, Pt) have been synthesized by reaction of 1-methyllumazine (MLM) and 1,6,7trimethyllumazine (MLMD) and different halide salts in acetonitrile solutions. These compounds have been characterized by means of analytical techniques (elemental analysis and TG), spectral methods (IR, 13 C and 1 H NMR, UV � /Vis � /NIR, EPR) and magnetics measurements. Single-crystal X-ray diffraction studies have been developed on the [CuCl2(MLM)2] and [PdBr2(MLM)2] complexes. In the complex Cu/MLM, a six-coordinated environment around metal ion is shown, with two pteridine ligands behaving in a bidentante manner through N5/O4 atoms being the other positions occupied by two chlorine atoms. The molecular unit of the compound Pd/MLM shows an ion Pd(II) linking to two bromide ions placed in a trans position, and two N5 atoms of two organic ligands, exhibiting a square-planar geometry as it is usual in complexes with d 8 -configuration ions.