Phpy bridged homodinuclear Ru-Ru () and heterodinuclear Ir-Ru complexes () have been developed. Complex induces autophagy towards the cisplatin resistant human breast cancer (MCF7) cell line, whereas is inactive.

Six mononuclear Ir complexes (1-6) using polypyridyl-pyrazine based ligands (L1 and L2) and {[cp*IrCl(μ-Cl)] and [(ppy)Ir(μ-Cl)]} precursors have been synthesised and characterised. Complexes 1-5 have shown potent anticancer activity against various human cancer cell lines (MCF-7, LNCap, Ishikawa, DU145, PC3 and SKOV3) while complex 6 is found to be inactive. Flow cytometry studies have established that cellular accumulation of the complexes lies in the order 2 > 1 > 5 > 4 > 3 > 6 which is in accordance with their observed cytotoxicity. No changes in the expression of the proteins like PARP, caspase 9 and beclin-1, Atg12 discard apoptosis and autophagy, respectively. Overexpression of CHOP, activation of MAPKs (P38, JNK, and ERK) and massive cytoplasmic vacuolisation collectively suggest a paraptotic mode of cell death induced by proteasomal dysfunction as well as endoplasmic reticulum and mitochondrial stress. An intimate relationship between p53, ROS production and extent of cell death has also been established using p53 wild, null and mutant type cancer cells.

A facile room temperature one-pot synthesis of trimetallic porous Au@Pd@Ru nanoparticles (Au@Pd@RuNPs) has been developed. The trimetallic nanoparticles have been prepared by the successive sacrificial oxidation of cobalt nanoparticles (CoNPs). The average particle size of Au@Pd@RuNPs is 110 nm. The porous nature and the presence of Au, Pd and Ru have been confirmed via TEM, FE-SEM and EDS analyses. The trimetallic nanoparticles have shown excellent catalytic activity towards the reduction of p-nitrophenol and efficient degradation of various azo dyes. This has been further extended towards the removal of colour from waste water via the catalytic degradation of azo dyes. Moreover, the produced amine can be eliminated from the waste water via its sorption on an industrial solid waste dolochar.

Herein, we report an example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction involving transfer hydrogenation of fluoroarylketone to the corresponding alcohol and Suzuki-Miyaura cross coupling reaction of the resulting fluoroarylalcohol under moderate reaction conditions, to biaryl alcohol. The complex with the shortest Pd-Pd distance exhibits the highest tandem activity among its di-metallic analogues, and exceeds in terms of activity and selectivity the analogous mononuclear compound. The kinetics of the reaction indicates clearly that reductive transformation of haloarylketone into haloaryalcohol is the rate determining step in the tandem reaction. Interestingly while fluoroarylketone undergoes the multistep tandem catalysis, the chloro-and bromoarylketones undergo only a single step C-C coupling reaction resulting in biarylketone as the final product. Unlike the pyrazole based Pd compounds, the precursor PdCl 2 and the phosphine based relevant complexes (PPh 3 ) 2 PdCl 2 and (PPh 3 ) 4 Pd are found to be unable to exhibit the tandem catalysis.

Imidazole-based cyclometalated iridium complexes [1]+–[5]+ have been developed displaying alkyl chain length dependent anticancer activity and imaging property.

Design and synthesis of the bis(pyrazol-1-yl)methane based bis-heteroscorpionate Pd-Ru complex results in efficient tandem Suzuki coupling/transfer hydrogenation reaction with a broad range of substrate reactivity.

Two mononuclear ruthenium complexes [(bpy)RuL/L](ClO) ([1]/[2]) (bpy-2,2' bipyridine, L = 2,3-di(pyridin-2-yl)pyrazino[2,3-f][1,10]phenanthroline) and L = 2,3-di(thiophen-2-yl)pyrazino[2,3-f][1,10]phenanthroline have been synthesized. The complexes have been characterized using various analytical techniques. The complex [1] has further been characterized by its single crystal X-ray structure suggesting ruthenium is coordinating through the N donors of phenanthroline end. Theoretical investigation suggests that the HOMOs of both complexes are composed of pyridine and pyrazine unit of ligands L and L whereas the LUMOs are formed by the contribution of bipyridine units. The low energy bands at ∼480 nm of the complexes can be assigned as MLCT with partial contribution from ligand transitions, whereas the rest are ligand centered. The complexes have shown Ru/Ru oxidation couples at E at 1.26 (70 mV) V and 1.28 (62 mV) V for [1] and [2] vs Ag/AgCl, respectively, suggesting no significant role of distal thiophene or pyridine units of the ligands. The complexes are emissive and display solvent dependent emission properties. Both complexes have shown highest emission quantum yield and lifetime in DMSO (ϕ = 0.05 and τ = 460 ns and λ at 620 nm for [1]; ϕ = 0.043 and τ = 425 ns and λ at 635 nm for [2]). Further, the long luminescent lifetime of these complexes has been utilized to generate reactive oxygen species for efficient azo dye decomposition.

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