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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.

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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...

Two new Cu(II) complexes [Cu 2 (L) 2 (mb)](ClO 4 )Á0.5H 2 O (1) and [Cu 4 (L) 4 (sq) (H 2 O) 2 ](ClO 4 ) 2 Á2H 2 O (2) (HL = 2-[(2-morpholine-4-yl-ethylimino)-methyl]phenol); mb = 4-methyl benzoate; sq 2À = C 4 O 4 2À squarate dianion) have been synthesized and characterized by single crystal X-ray analysis, electrospray ionization mass spectrometry, and infrared spectroscopic technique. The structural determination showed the Schiff base acting as tridentate ligand coordinating the copper(II) atoms by the phenoxo, imino and morpholine nitrogen donors to give comparable Cu(L) entities in both complexes 1 and 2. Complex 1 is a dinuclear cationic species built by a 4-methylbenzoate anion coordinating two Cu(L) moieties. The two Cu(II) centers are chemically equivalent exhibiting a distorted square pyramidal geometry. Complex 2 is tetranuclearand it is formed by a centrosymmetric squarate core connected to four Cu(L) complex units to give a cationic complex counterbalanced by perchlorate anions. Of the two independent Cu(II) atoms, Cu1 exhibits a square pyramidal coordination sphere, whereas Cu2 is better described as square planar.The crystal packing of complex 2 shows a polymeric arrangement through H-bonding. Magnetic measurements show antiferromagnetic coupling in both the complexes. The interaction of complexes with hen egg lysozyme has been investigated by using UV-vis absorption and 2D/3D fluorescence spectroscopic techniques and the calculated values of binding constants, K bin , are (5.9 ± 0.11) Â 10 4 , (17.39 ± 0.04) Â 10 4 , and (10.1 ± 0.07) Â 10 4 M À1 for HL, 1, and 2, respectively.