Cytotoxic gold(iii) complexes incorporating a 2,2':6',2''-terpyridine ligand framework - the impact of the substituent in the 4'-position of a terpy ring.

Two gold(iii) complexes incorporating 2,2':6',2''-terpyridine derivatives have been synthesised and characterized, and the possibility of tuning the cytotoxic activity by structural modifications of a terpy ligand has been examined. Both complexes [AuCl(4'-R1-terpy)](PF6)2 (1) and [AuCl(4'-R2-terpy)](PF6)2 (2), where R1 is 2-pyridyl and R2 is 3-pyridyl, show good anti-proliferative activities against HCT116, which are higher in relation to those of the free ligands, [AuCl(terpy)](PF6)2 and standard anticancer drug cisplatin. The cytotoxic properties of the gold complexes were examined by MTS assay, cell cycle and apoptosis analysis, ROS measurements, determination of mitochondrial membrane potential and mass, and staining of phosphatidylserine with Annexin-V antibody FITC-conjugated together with PI.

Synthesis, crystal structure and magnetic properties of H2tppz[ReCl6] and [Cu(bpzm)2(µ-Cl)ReCl3(µ-ox)Cu(bpzm)2(µ-ox)ReCl3(µ-Cl)]n.

Two new Re(iv) compounds of formulae H2tppz[ReCl6] (1) and [Cu(bpzm)2(µ-Cl)ReCl3(µ-ox)Cu(bpzm)2(µ-ox)ReCl3(µ-Cl)]n (2) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpzm = bis(pyrazolyl-1-yl)methane] have been prepared and their crystal structures determined by X-ray diffraction on single crystals. Compound 1 is a mononuclear species whose structure consists of octahedral hexachlororhenate(iv) anions and diprotonated H2tppz(2+) cations which are arranged in the unit cell as alternating anionic and cationic layers, held together by electrostatic forces. The structure of 2 is made up of alternating [Cu(1)(bpzm)2](2+) and [(ox)ReCl3(µ-Cl)Cu(2)(bpzm)2(µ-Cl)ReCl3(ox)](2-) entities interlinked by oxalate bridges to afford a neutral heterobimetallic chain. The oxalate group adopts the didentate (at Re)/monodentate (at Cu) bridging mode. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.9-295 K. 1 is a magnetically diluted Re(iv) complex, the relatively large value of the zero-field splitting of the ground level [D = -15.8(2) cm(-1)] accounting for the variation of χMT in the low temperature range. Weak intrachain ferromagnetic interactions between Re(iv) and Cu(ii) through oxalate (J1 = +0.15 cm(-1)) and single chloro (J2 = +4.9 cm(-1)) bridges occur in 2 which are obscured by the large zero-field splitting of the Re(iv) ion (DRe = 42 cm(-1)). In addition, interchain antiferromagnetic interactions are also involved in 2 which are responsible for the metamagnetic behavior observed, the value of the critical dc magnetic field (Hc) being 20 kOe.