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Zn(II) complexes MTPY–ZnCl2(C1) and MTPY–Zn(NO3)2(C2) based on a new D–A type ligand MTPYinvolving phenothiazine donor and terpyridine acceptor units have been described. The ligand MTPYand complexes C1and C2display intramolecular charge transfer and substantial solvatochromism. Solid-state emission studies on MTPYfurther substantiated the occurrence of concentration-induced emission in this molecule. In addition, the complexes C1and C2displayed a solvent-dependent self-assembly which has been examined as a function of the hydrophilic and hydrophobic nature of the solvent systems. The role of hydrophilicity/hydrophobicity of a solvent and compounds on morphology and emission characteristics of the self-assembled aggregates has been investigated by UV–vis, emission, and scanning electron microscopy studies. In addition, it has been categorically shown that aggregation-induced emission in C1offers a simple, sensitive, and rapid means for the detection of pyrophosphates (PPi) in the aqueous medium. Job’s plot analysis suggested a 3:1 binding stoichiometry between C1and PPi, which has been supported by electrospray ionization mass spectrometry and density functional theory. Further, higher affinity of PPitoward C1over C2has also been rationalized by theoretical studies.

A pyrazole-appended quinoline-based 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (L1, BODIPY) has been synthesized and used as a ligand for the preparation of iridium(III) complexes [Ir(phpy)2(L1)]PF6(1; phpy = 2-phenylpyridine) and [(η5-C5Me5)Ir(L1)Cl]PF6(2). The ligand L1and complexes 1and 2have been meticulously characterized by elemental analyses and spectral studies (IR, electrospray ionization mass spectrometry, 1H and 13C NMR, UV/vis, fluorescence) and their structures explicitly authenticated by single-crystal X-ray analyses. UV/vis, fluorescence, and circular dichroism studies showed that complexes strongly bind with calf-thymus DNA and bovine serum albumin. Molecular docking studies clearly illustrated binding through DNA minor grooves via van der Waals forces and their electrostatic interaction and occurrence in the hydrophobic cavity of protein (subdomain IIA). Cytotoxicity, morphological changes, and apoptosis have been explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst 33342 staining. IC50values for complexes (1, 30 μM; 2, 50 μM) at 24 h toward the human cervical cancer cell line (HeLa) are as good as that of cisplatin (21.6 μM) under analogous conditions, and their ability to kill cancer cells lies in the order 1> 2. Because of the inherent emissive nature of the BODIPY moiety, these are apt for intracellular visualization at low concentration and may find potential applications in cellular imaging and behave as a theranostic agent.