6,6″-Dimethyl-2,2′:6′,2″-terpyridine revisited: New fluorescent silver(I) helicates with in vitro antiproliferative activity via selective nucleoli targeting

• Four new helical silver(I) architectures were synthesized and characterized.
• Coordination modes of terpyridine ligand are counterion and solvent dependent.
• Silver(I) complexes exhibit antitumour and antibacterial behaviour.
• Specific mechanism of action was determined to involve intercalation with DNA.
• Complexes were found to specifically permeate to nucleoli and bind with DNA in vivo.

6,6″-Dimethyl-2,2′:6′,2″-terpyridine ligand (L) reacts in equimolar ratio with Ag(I) ions what results in formation of dinuclear double helicates, which differ in terms of framework and complexity in accordance to counterions and solvent applied. Obtained complexes were thoroughly studied in terms of their biological activity, with the positive antiproliferative outcome on three human cancer cell lines: human breast cancer (T47D), human cervical carcinoma (HeLa) and human lung cancer (A-549). Performed DNA binding experiments showed that given Ag(I) species specifically interact with DNA double helix via intercalation and were visualized by confocal microscopy to specifically bind to the nuclei. All newly synthesized helical systems exhibit promising antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacterial strains. Spectrophotometric properties were described as fulfilment of structural studies of newly presented complexes confirming their helical structure in solution.

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