1,2-Bis[(2,2':6',2''-terpyridin-4'-yl)-oxy]ethane.

The title compound, C(32)H(24)N(6)O(2), has an inversion centre located at the mid-point of the central C-C bond of the diether bridging unit. The terminal pyridine rings are canted relative to the central pyridine ring, with dihedral angles of 12.98 (6) and 26.80 (6)°. The maximum deviation from the eight-atom mean plane, defined by the two bridging O and C atoms and the central pyridine ring, is 0.0383 (10)° for the N atom.

1,6-Bis[(2,2':6',2''-terpyridin-4'-yl)-oxy]hexa-ne.

The mol-ecule of the title compound, C(36)H(32)N(6)O(2), lies about an inversion center, located at the mid-point of the central C-C bond of the diether bridge. The terminal pyridine rings form dihedral angles of 4.67 (7) and 26.23 (7)° with the central ring. In the crystal, weak C-H⋯N and C-H⋯O inter-actions link the mol-ecules into a three-dimensional network.

1,4-Bis[(2,2':6',2''-terpyridin-4'-yl)-oxy]butane.

The title compound, C(34)H(28)N(6)O(2), has an inversion centre located at the mid-point of the central C-C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Šabove the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1)°, repectively. In the crystal, weak C-H⋯N inter-actions link the mol-ecules into infinite chains parallel to the a axis.

Electrostatic repulsion between the cations of (1-methyl-1H-imidazole-κN)(2,2':6',2''-terpyridine-κN,N',N'')platinum(II) perchlorate nitro-methane monosolvate prevents Pt⋯Pt inter-actions.

The reaction between [Pt(terpy)Cl]·2H(2)O (terpy = 2',2'':6',2''-terpyridine) and 1-methyl-imidazole (MIm) in the presence of two equivalents of AgClO(4) in nitro-methane yields the title compound, [Pt(C(15)H(11)N(3))(C(4)H(6)N(2))](ClO(4))(2)·CH(3)NO(2). The dicationic complexes are arranged in a staggered configuration. The torsion angle subtended by the 1-methyl-imidazole ring relative to the terpyridine ring is 114.9 (5)°. Inter-molecular C-H⋯O inter-actions between the perchlorate anions and the H atoms of the terpy ligand are observed. Consideration of related phenyl-bipyridyl complexes of platinum(II), which are monocationic, leads to the conclusion that the electrostatic repulsion between the dicationic chelates prevents the formation of Pt⋯Pt inter-actions. These inter-actions are a common feature associated with the monocationic species.

(1H-pyrazole-κN2)(2,2':6',2''-terpyridine-κ3N,N',N'')platinum(II) bis(perchlorate) nitromethane monosolvate.

The reaction between [PtCl(terpy)]·2H(2)O (terpy is 2,2':6',2''-terpyridine) and pyrazole in the presence of two equivalents of AgClO(4) in nitromethane yields the title compound, [Pt(C(3)H(4)N(2))(C(15)H(11)N(3))](ClO(4))(2)·CH(3)NO(2), as a yellow crystalline solid. Single-crystal X-ray diffraction shows that the dicationic platinum(II) chelate is square planar with the terpyridine ligand occupying three sites and the pyrazole ligand occupying the fourth. The torsion angle subtended by the pyrazole ring relative to the terpyridine chelate is 62.4 (6)°. Density functional theory calculations at the LANL2DZ/PBE1PBE level of theory show that in vacuo the lowest-energy conformation has the pyrazole ligand in an orientation perpendicular to the terpyridine ligand (i.e. 90°). Seemingly, the stability gained by the formation of hydrogen bonds between the pyrazole NH group and the perchlorate anion in the solid-state structure is sufficient for the chelate to adopt a higher-energy conformation.

Three new asymmetric trans-amine(azole)dichloridoplatinum complexes that overcome cisplatin resistance and their reactions with 5'-GMP.

Three new asymmetric platinum(II) complexes comprising an isopropylamine ligand trans to an azole ligand were synthesized and fully characterized by (1)H NMR, (195)Pt NMR, IR and elemental analysis. In addition the X-ray crystal structure of all three complexes was determined. The reaction kinetics of the complexes with DNA model base guanosine-5'-monophosphate (GMP) was studied, revealing reaction kinetics comparable to cisplatin. To gain insight in the complexes as potential antitumor agents, cytotoxicity assays were performed on a variety of human tumor cell lines. These assays showed the complexes all to possess cytotoxicity profiles comparable to cisplatin. Furthermore, the complexes largely retain their activity in a human ovarian carcinoma cell line resistant to cisplatin, A2780R, compared to the cisplatin sensitive parent cell line A2780. These results are of fundamental importance, illustrating how platinum complexes of trans geometry can show improved activity compared to cisplatin in both cisplatin sensitive and cisplatin resistant cell lines.