Four new Co II complexes, [Co(bpy) 2 (acac)]Cl (1), [Co-(phen) 2 (acac)]Cl (2), [Co(bpy) 2 (cur)]Cl (3), [Co(phen) 2 (cur)]Cl (4), where bpy = 2,2'-bipyridine (1 and 3), phen = 1,10-phenanthroline (2 and 4), acac = acetylacetonate (1 and 2), cur = curcumin monoanion (3 and 4) have been designed, synthesized and fully characterized. The X-ray crystal structures of 1 and 2 indicated that the CoN 4 O 2 core has a distorted octahedral geometry. The photoactivity of these complexes was tuned by varying the π conjugation in the ligands. Curcumin complexes 3 and 4 had an intense absorption band near 435 nm, which made them useful as visible-light photodynamic therapy agents; they also showed fluorescence with λ em � 565 nm. This fluorescence was useful for studying their intracellular uptake and localization in MCF-7 breast cancer cells. The acetylacetonate complexes (1 and 2) were used as control complexes to understand the role of curcumin. The white-light-triggered anticancer profiles of the cytosol targeting complexes 3 and 4 were investigated in detail. These non-dark toxic complexes displayed significant apoptotic photo-cytotoxicity (under visible light) against MCF-7 cells through ROS generation. The control complexes 1 and 2 did not induce significant cell death in the light or dark. Interestingly, 1-4 produced a remarkable antibacterial response upon light exposure. Overall, the reported results here can increase the boundary of the Co II -based anticancer and antibacterial drug development.

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The recent dramatic enhancement in the cancer-related mortality and drawbacks (side effects and resistance) of Pt-based first-generation chemotherapeutics have escalated the need for new cancer medicines with unique anticancer activities...

Sonodynamic therapy (SDT) for cancer treatment is gaining attention owing to its non‐invasive property and ultrasound‘s (US) deep tissue penetration ability. In SDT, US activates the sonosensitizer at the target deep‐seated tumors to generate reactive oxygen species (ROS), which ultimately damage tumors. However, drawbacks such as insufficient ROS production, aggregation of sonosensitizer, off‐target side effects, etc., of the current organic/nanomaterial‐based sonosensitizers limit the effectiveness of cancer SDT. Very recently, metal complexes with tunable physiochemical properties (such as sonostability, HOMO to LUMO energy gap, ROS generation ability, aqueous solubility, emission, etc.) have been devised as effective sonosensitizers, which could overcome the limitations of organic/nanomaterial‐based sonosensitizers. This concept introduces all the reported metal‐based sonosensitizers and delineates the prospects of metal complexes in cancer sonodynamic therapy. This new concept of metal‐based sonosensitizer can deliver next‐generation cancer drugs.

Recently, interest has been given to developing photocatalytic anticancer drugs. This area of research is dominated by metal complexes. Here, we report the potential of lysosome/mitochondria targeting cyanine appended bipyridine compounds as the organic photocatalytic anticancer agents. The organocatalyst (bpyPCN) not only exhibits light-induced NADH oxidation but also generates intracellular ROS to demonstrate anticancer activity. This is the first example of organic compound induced catalytic NADH photo-oxidation in an aqueous solution and in cancer cells.