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Two novel coordination compounds of cadmium, [Cd2L1(ssal)2(H2O)3]2·10H2O (1) and {[Cd2L1(dca)4(H2O)]·H2O} n (2) (where L1 = 2,2′,2″-(1-(pyridin-2-ylmethyl)­imidazolidine-2,4,5-triyltripyridine), ssal = sulfosalicylate, and dca = dicyanamide), have been synthesized under reflux conditions. The nitrogen-rich ligand L1 was formed in situ by Cd­(II)-mediated coupling cycloaddition of the Schiff base N-(2-pyridylmethyl)­pyridine-2-carbaldimine: thus, through a Cd­(II)-catalyzed reaction. In the two species sulfosalicylate or dicyanamide anions act as a coligand. The single-crystal X-ray structural analyses revealed that 1 is a discrete centrosymmetric tetranuclear complex crystallizing with 10 lattice water molecules that favor the formation of a 3D supramolecular structure through H bonds. On the other hand complex 2 is a coordination polymer built by bridging dca anions connecting −[Cd1­(L1)­Cd2]– building blocks. The polymers are further connected by H bonds involving the coordinated and lattice water molecules with terminal dca N atoms of symmetry-related chains. The luminescent properties of complexes 1 and 2 were investigated in various organic solvents, and both complexes show a highly selective sensitive response toward nitroaromatic compounds, especially toward picric acid (PA). The possible quenching mechanism of the process has been validated by the combined effect of energy and electron transfer mechanisms as well as electrostatic interactions.

Copper(II) complexes {[Cu(HL)(ClO4)(H2O)](ClO4)⋅3H2O} (1), {[Cu(HL)(m‐phth)]⋅5H2O} (2) and {[Cu(HL)(NCS)]2(ClO4)2⋅2H2O} (3) (HL=2‐{[2‐(1‐piperazinyl)ethylimino]methyl}phenol; m‐phth=1,3‐benzenedicarboxylate] have been synthesized and characterized by structural determination and spectroscopic studies. The mononuclear square pyramidal complex 1 resulted from the reaction of HL with copper perchlorate hexahydrate. Then mononuclear square planar complex 2 and dinuclear thiocyanato bridged complex 3 were obtained by reacting 1 with disodium 1,3‐benzenedicarboxylate (Na2(m‐phth)) and potassium thiocyanate, respectively. The interactions of 1–3 with CT‐DNA / serum albumins were investigated by UV‐visible absorption and fluorescence spectroscopy. The intrinsic binding constants of 1, 2 and 3 with CT‐DNA were calculated as 1.44 (±0.13) × 105, 4.86 (±0.11) × 105 and 4.51 (±0.16) × 105 L mol−1, respectively. Study of the interactions of 1–3 with human serum albumin (HSA) / bovine serum albumin (BSA) showed that all the complexes could quench intrinsic fluorescence of HSA and BSA through a static quenching process. Molecular docking technique was utilised to confirm the mode of interaction of complexes with CT‐DNA / serum albumin. Anticancer activities of the complexes have been tested using human breast cancer cell lines MCF7 and MBA‐MB‐231. Among the complexes studied 3 shows the higher cytotoxic activity and growth inhibition of cancer cells via induction of apoptotic cell death.

Two novel copper(II) complexes, [Cu4(L)2(LH)2(H2O)2]2(NO3)2. (pydc).9H2O (1) and {[Cu4(L)2(LH)2(H2O)2(ppda)].5H2O}n (2) [H2L=2‐[(2‐hydroxy‐ethylimino)‐methyl]‐6‐methoxy‐phenol, pydc=pyridine‐3,5‐dicarboxylate, ppda=phenylene‐1,4‐diacrylate]have been synthesized and characterised by X‐ray single crystal diffraction analysis and low temperature magnetic study. The structural determination reveals for complex 1 a tetranuclear species exhibiting a double‐open cubane like core framework, whereas use of ppda anions results 1D coordination polymer where tetranuclear double‐open cubane cores are connected by bridging ppda ligands. In both the complexes, hydrogen bonding interactions lead to 3D supramolecular structures. Low temperature magnetic study indicates antiferromagnetic coupling in both the complexes. A model based on an effective square tetramer of Heisenberg spins was used to determine exchange strengths of 174(2) K for 1 and 107.4(4) K for 2.

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Tetra/tri nuclear Ni(II) complexes namely[Ni4(L)4(H2O)4].5(dmf).7(H2O) (1) and [Ni3(L)2(bz)2(dmf)2(H2O)2] (2) [H2L = N-(2-(hydroxy)-3-methoxybenzylidene)tryptophan); dmf = dimethyl formamide, bz = benzoate anion] have been synthesized and characterized by X-ray single crystal structure...