Cytotoxic Activities of Bis‐cyclometalated Rhodium(III) and Iridium(III) Complexes Containing 2,2’‐Biphenyldiamine

Abstract

The synthesis and characterization of new bis‐cyclometalated complex salts [M(ptpy)2(2,2’‐biphenyldiamine)]PF6 (M=Rh, 1; M=Ir, 2; ptpy=2‐(p‐tolyl)pyridinato) are described. Compounds 1 and 2 were obtained by bridge‐splitting reactions of [{M(μ‐Cl)(ptpy)2}2] (M=Rh or Ir) with 2,2’‐biphenyldiamine in CH2Cl2/MeOH/H2O mixtures. The molecular structure of compound 2 in the crystal was confirmed by single‐crystal X‐ray diffraction. 2 crystallized from dichloromethane/methanol/n‐heptane in the monoclinic space group P21/n. The cytotoxic activities of both new compounds were examined and evaluated. Compound 1 and 2 exhibit significant cytotoxicity against human cancer cell lines with the IC50 values in the low micromolar range.

Cytotoxic Activities of Bis‐cyclometalated Iridium(III) Complexes Containing Chloro‐substituted κ2N‐terpyridines

“…Thus, the three important bond angles in the central core of 1 (compare caption in Figure 1) agree very well with the reported corresponding ones for [Ir(ppy) 2 (κ 2 N ‐terpy‐Cl)] + : N6−Ir2−N7, 76.40(15); N9−Ir2−C63, 80.19(16) and N10−Ir2−C74, 81.12(18) [12] . The Ir−N and Ir−C bond parameters within the cyclometalated chelating ring systems were in good accordance with the usually observed ones in related compounds reported by us [11] . Compound 2 crystallized from a dichloromethane/methanol/ iso ‐hexane mixture in the triclinic space group P − 1 with four molecules in the unit cell.…”

“…[12] The IrÀ N and IrÀ C bond parameters within the cyclometalated chelating ring systems were in good accordance with the usually observed ones in related compounds reported by us. [11] Compound 2 crystallized from a dichloromethane/methanol/ iso-hexane mixture in the triclinic space group P À 1 with four molecules in the unit cell. An ORTEP view of the molecular structure of cations in 2 is shown in Figure 2.…”

“…[10] In the course of related investigations we have a current interest in studies of the cytotoxic activity of bis-cyclometalated iridium(III) compounds towards some human cancer cell lines by examining the substituent influences in the sphere of the ancillary ligands. [11] Herein we describe the synthesis and the characterization of two new cyclometalated iridium(III) compounds of the type [Ir(ptpy) 2 (N^N)]PF 6 [N^N = k 2 N-terpy-C 6 H 4 Clp = 4'-(4-chlorophenyl)-2,2':6',2''-terpyridine (1), and N^N = k 2 Nterpy-Cl = 4'-chloro-2,2':6',2''-terpyridine (2)]. Beside studies of the photophysical properties of 1 and 2, which were supported by DFT and TD-DFT calculations, we demonstrated the potent in vitro antiproliferative activity of these new compounds.…”