Quanyun Xu

X-ray crystal structure of tetrachloro(trans-d,l-1,2-diaminocyclohexane) platinum(IV) complex: A potential anticancer agent

Tetrachloro(trans-d,l-1,2-diaminocyclohexane)platinum(IV) complex (tetraplatin or ormaplatin) has been recognized as a potential anticancer agent. We have determined the crystal structure of this compound by x-ray single crystal diffraction. It has a unique space group and rare molecular packing. Parameters are as follows: space group R3c (rhombohedral), a = 26.425(4) A, alpha = 54.50(1) degrees; V = 11375A3, Z = 36. The coordination about Pt atoms is a slightly distorted octahedron owing to the presence of the geometrically strained five-membered ring (avg. N-Pt-N angle = 82.9 degrees). An intricate network of intermolecular hydrogen bonds holds the crystal lattice together. Three independent ormaplatin molecules surround each water molecule, forming the three shortest A...B contacts and thus the three strongest hydrogen bonds.

Synthesis and characterization of N-methyliminodiacetato trans-R,R-, trans-S,S-, and cis-1,2-diaminocyclohexane platinum (IV) complexes: Crystal structure of chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato)platinum(IV) chloride

The compounds, chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato)platinum(IV) chloride, chloro(trans-S,S-1,2-diaminocyclohexane)(N-methyliminodiacetato) platinum(IV) chloride, and chloro(cis-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum (IV) chloride, were prepared and characterized by elemental analysis, IR, and 195Pt NMR. The crystal structure of one of these three compounds, chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato) platinum(IV) chloride, was determined by x-ray single crystal diffraction. This compound is particularly interesting because the 1,2-diaminocyclohexane (DACH) ring is in a twist-boat configuration rather than the chair configuration previously reported for other DACH platinum compounds. The crystal structure consists of two independent cations and anions, with all atoms between these two independent molecules (except those in the chiral DACH) related by a pseudo-inversion center. Both platinum atoms have slightly distorted octahedral coordination, with angles ranging from 81.8 to 100.8 degrees. Crystallographic details: space group P2(1) (monoclinic); a = 19.864(5) A, b = 7.026(2) A, c = 12.446(3) A, beta = 106.64(2) degrees; Z = 4; R = 0.036 for 2333 reflections.

The X-ray crystal structure of the trans-dl-1,2-diaminocyclohexane-(N-methyliminodiacetato)platinum(II) complex

Abstract The crystal structure of the trans-dl-1,2-diaminocyclohexane(N-methyliminodiacetato)platinum(II) complex has been determined by X-ray diffraction. It has the following parameters: space group P21/c (monoclinic), a=11.272(5), b=14.034(7), c=10.163(5) A, β=116.13(3)°, Z=4. The slightly distorted square plane of the Pt includes two nitrogens of the diamine in cis positions and one oxygen and one nitrogen from N-methyliminodiacetate ion. The PtN and PtO distances average 2.038 and 2.013 A, respectively. An intricate system of hydrogen bonds which involves every hydrogen atom not attached to carbon was observed. The molecule is a zwitterion and the charge density on the unbound carboxylate is probably stabilized through this series of strong hydrogen bonds.

Synthesis, characterization, and antitumor activity of 1,2-bis(diphenylphosphino) ethane platinum(II) and palladium(II) complexes

A number of 1,2-bis(diphenylphosphino)ethane monomeric platinum(II) and palladium(II) complexes have been synthesized in light of their potential antitumor activity. The metal center is coordinated with a number of carboxylate anions in the cis-configuration. These complexes have been characterized by elemental analysis, conductivity measurement, and various spectroscopic techniques [IR and 195Pt NMR]. In vivo screening tests for activity of these complexes were performed against the L1210/0 murine leukemia cancer model, but none displayed a significant level of antitumor activity.

Synthesis and X-ray crystal structure of cis-1,4-diaminocyclohexanetetrachloroplatinum(IV): A new antitumor agent

Abstract cis-1,4-Diaminocyclohexanetetrachloroplatinum(IV), a new antitumor agent, has been synthesized, where cis-1,4-diaminocyclohexane (cis-i,4-DACH) is a novel carrier ligand. The structure of this complex has been determined by single crystal X-ray diffraction method. The crystal parameters are as follows: space group P 1 . (triclinic), a=6.880(2), b=8.177(3), c=11.784(4) A, Z=2. The platinum has a slightly distorted octahedral coordination with two adjacent corners being occupied by the two amino nitrogens of cis-1,4-DACH, and the remaining two equatorial and two axial positions are bound to four chloride ions. The cis-1,4-DACH is in a twist-boat conformation, which is necessitated by binding to platinum. It forms a seven-membered chelating ring with platinum, leading to considerable strain in bidentate DACH binding. This strain is evidenced by the large 125.7° C-N-Pt angle. The N-Pt-N angle is expanded to 98.4° owing to geometric constraints of the cis-1,4-DACH geometry.

Synthesis, Characterization, and Antitumor Activity of New Chloroethylamine Platinum Complexes

A series of cis-bis-(2-chloroethylamine)platinum(II) and platinum(IV) complexes were synthesized and characterized by elemental analysis, IR, and 1H and 195Pt NMR spectroscopic techniques. Complexes were tested in vitro against murine L1210 leukemia and human ovarian A2780 cell lines and in vivo against the L1210 leukemia model. Some of these complexes showed excellent antitumor activity in both systems. However, all were inactive against cisplatin-resistant A2780/CP cells.

Synthesis, characterization, and antitumor activity of amine platinum(II) and (IV) tellurate complexes

A series of novel water-soluble amine platinum (II) tellurate complexes of the type (A)Pt(II) [TeO2(OH)4], where A = 1,2-diaminocyclohexane (DACH), 1,1-bis(aminomethyl)cyclohexane (AMCH), ethylenediamine (en), or cyclopentylamine (cpa), were prepared either by the reaction of amineplatinum (II) sulfate with barium tellurate or by a direct reaction of (A)Pt(OH)2 with telluric acid. Oxidation of the amine platinum(II) tellurate produced amine platinum(IV) tellurate (A)Pt(IV)trans(Z) [TeO2(OH)4] complexes, where Z = OH or Cl, following oxidation with hydrogen peroxide or with chlorine gas, respectively. Complexes were characterized by elemental analysis, and IR and 195Pt NMR spectroscopy. Against i.p. murine leukemia cells in vivo, some of the complexes displayed good antitumor activity when administered intraperitoneally (i.p.) on days 1, 5, and 9 at their optimal doses. Pt(II) complexes containing R,R-DACH, S,S-DACH, R,R-S,S-DACH, or AMCH produced %T/C of 147 to 288 whereas cis-DACH, en, and cpa complexes were inactive. In the Pt(IV) series, the R,R-DACH complex with axial Cl was highly active (%T/C = 371, 40% cures) compared with the complex with axial OH (%T/C = 135).

Crystal structures of bis(L(-)prolinato-N)(trans-R,R-1,2-diaminocyclohexane)platinum(II) and bis(L(-)prolinato-N)-(cis-1,2-diaminocyclohexane)platinum(II) complexes

Abstract The molecular structures of the compounds bis( L (-)prolinato- N )( trans - R , R -1,2-diaminocyclohexane)platinum(II) and bis( L (-)prolinato- N )( cis -1,2-diaminocyclohexane)platinum(II) have been established by single crystal X-ray diffraction. The average plane of the cyclohexane ring of the cis -DACH is nearly perpendicular to the PtN 4 plane, while the ring of the trans - R , R -DACH is nearly coplanar with PtN 4 . Two prolinate ligands are bound to the platinum through amino nitrogen atoms. Crystallographic details: bis( L (-)prolinato- N )( trans - R , R -1,2- diaminocyclohexane)platinum(II): space group P 2 1 2 1 2 1 (orthorhombic), a = 10.301(2), b = 12.364(2), c = 17.920(4) A, Z = 4, R = 0.019; bis( L (-)prolinato- N )( cis -1,2-diaminocyclohexane)platinum(II): space group P 2 1 2 1 2 1 (orthorhombic), a = 11.496(5), b = 12.918(6), c = 16.527(9) A, Z = 4, R = 0.040.

Preparation, characterization, and antitumor activity of water-soluble aminoalkanol platinum(II) complexes

A new series of highly water-soluble aminoalkanol platinum(II) complexes have been synthesized and characterized by elemental analysis, conductance, IR, and 195Pt NMR. Preliminary in vitro and in vivo screening tests for antitumor activities of these complexes against L1210 murine leukemia were performed. In general, these compounds were far less cytotoxic than cisplatin and possessed only a moderate degree of antitumor activity.

Synthesis and characterization of a series of hydrophobic antitumor amine platinum(II) carboxylates

Abstract As part of a systematic study, a series of hydrophobic amine platinum(II) carboxylate complexes has been prepared as potential antitumor agents in a liposomal-entrapped form. These complexes have been characterized by elemental analysis, 1R, 13C and 195Pt NMR spectroscopic techniques. Effect of ligand donors on NMR chemical shift is briefly discussed.