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A diformyl-p-cresol (DFC)-8-aminoquinoline based dual signaling probe was found to exhibit colorimetric and fluorogenic properties on selective binding towards Mg2+ and Zn2+. Turn-on fluorescent enhancements (FE) as high as 40 fold and 53 fold in 9 : 1 MeCN/water (v/v) at pH 7.2 in HEPES buffer for Mg2+ and Zn2+, respectively, were observed. The binding constants determined from the fluorescence titration data are: K = (1.52 ± 0.21) × 105 M−1 and (9.34 ± 4.0) × 103 M−2 at n = 1 and 0.5, for Mg2+ and Zn2+, respectively. The L : M binding ratios were also determined by Job's method, which support the above findings. This is further substantiated by HRMS analysis. Due to solubility in mixed organo-aqueous solvents as well as cell permeability it could be used for the in vitro/in vivo cell imaging of Mg2+ and Zn2+ ions with no or negligible cytotoxicity. This probe could be made selective towards Mg2+ over Zn2+ in the presence of TPEN, both under intra- and extracellular conditions and is superior to other Mg2+ probes which suffer from selectivity of Mg2+ over Ca2+ or Zn2+. Furthermore the dissociation constant (Kd = 6.60 μM) of the Mg2+-(DFC-8-AQ) complex is far lower than the so far reported Mg2+ probes which fall in the mM range. [ABSTRACT FROM AUTHOR]

A new rhodamine-based dual signaling probe ( L3) has been found to display quick responses through visible colorimetric changes as well as fluorogenic properties on selective 1:1 binding to Hg2+, as delineated by absorption and fluorescence titrations as well as by Job′s method and ESI-MS+ studies. The fluorescent probe L3 displays a 252-fold fluorescence enhancement on binding to Hg2+. A Benesi-Hilderband fit of the absorption titration data gives Kd = (32.01 ± 0.74) μ M and a 1:1 binding stoichiometry. Owing to its solubility in mixed organic/aqueous solvents as well as its cell permeability, L3 could be used for in vitro/in vivo cell imaging of Hg2+ with no or negligible cytotoxicity. The detection limit of Hg2+ was calculated by the 3σ method to be 9.28 ng L-1. Moreover, the fluorescence of the L3-Hg2+ system was turned off and its red colour disappeared when KI was added. Thus, the 'OFF-ON-OFF' fluorescence sensing behaviour of L3 observed in the presence of Hg2+ and I- may find applications in devices with logic gate functions. [ABSTRACT FROM AUTHOR]

Abstract: The syntheses, and structural characterization of seven heterodinuclear complexes: [CuII (HL)NaI(NO3)(MeOH)] (1), [CuII(HL)ZnII(H2O)(NO3)](NO3) (2), [CuII(HL)HgII(Cl)2] (3), [CuII(H2O)(HL)SmIII(NO3)3] (4), [CuII(H2O)(HL)BiIII(NO3)3] (5), [CuII(HL)PbII(NO3)2] (6) and [CuII(HL)CdII(NO3)2] (7) are reported, where H3L=N,N′-bis(3-methoxysalicylaldiimine)-1,3-propylene-2-ol. Compounds 1 and 3 crystallize in the monoclinic P21/n space group, 4, 5 and 7 in the monoclinic P21/c space group, while the space group of complexes 2 and 6 is triclinic . The X-ray crystallography reveals that the structures of all the complexes consist of diphenoxo-bridged heterometallic cores in which CuII metal ion is trapped in N2O2 compartment of the Schiff-base ligand, while the second metal ion is present in the larger and open O4 [O(phenoxo)2O(methoxy)2] compartment. NaI and ZnII ions in 1 and 2, respectively, are six coordinated, while PbII ion in 6 and CdII ion in 7 are eight coordinated. HgII ion in 3 is six coordinated, while both SmIII and BiIII ions in 4 and 5, respectively, are surrounded by 10 oxygen atoms involving four O atoms from the outer compartment of the ligand and six from three chelating nitrates. In all the cases, non-coordinated –OH group plays significant role in the construction of diverse supramolecular aggregates through hydrogen bonding: two dimensional (2D) in 1 and 3, one dimensional (1D) in 2, 4, 5 and 6, while dimeric in 7. In addition to the structural diversity, the structural resemblance of bismuth(III) with member of a lanthanum family, samarium(III), is noted. In fact, they are found to be isostructural and isomorphous in the present study. Most importantly, compound 3 exhibits a rare feature of helical twisting for the coordinated Schiff-base ligand that arises due to the fact that the metal ion is too large to fit into the wider O4 compartment. [Copyright &y& Elsevier]

Abstract: X-ray crystallographic study on [CoII(cyclam)Cl2]·3H2O (cyclam=1,4,8,11-tetraazacyclotetradecane) reveals that the three water molecules form water pentamers, four of such adjacent water pentamers are fused together to form boat-shaped dodecamers (H2O)12 which are further H-bonded to form 2D water layers. Between the successive water layers, H-bonded 1D chains of [Co(cyclam)Cl2] monomers are sandwiched and stacked along the crystallographic c-direction. Thermal studies reveal that the coordinated water molecules are strongly bound to the polymeric framework which can be thermally dehydrated and readsorbed, as evidenced by the PXRD studies of the parent, dehydrated and rehydrated forms of the complex. [Copyright &y& Elsevier]

A diformyl-p-cresol (DFC)-8-aminoquinoline based dual signaling probe was found to exhibit colorimetric and fluorogenic properties on selective binding towards Mg(2+) and Zn(2+). Turn-on fluorescent enhancements (FE) as high as 40 fold and 53 fold in 9 : 1 MeCN/water (v/v) at pH 7.2 in HEPES buffer for Mg(2+) and Zn(2+), respectively, were observed. The binding constants determined from the fluorescence titration data are: K = (1.52 ± 0.21) × 10(5) M(-1) and (9.34 ± 4.0) × 10(3) M(-2) at n = 1 and 0.5, for Mg(2+) and Zn(2+), respectively. The L : M binding ratios were also determined by Job's method, which support the above findings. This is further substantiated by HRMS analysis. Due to solubility in mixed organo-aqueous solvents as well as cell permeability it could be used for the in vitro/in vivo cell imaging of Mg(2+) and Zn(2+) ions with no or negligible cytotoxicity. This probe could be made selective towards Mg(2+) over Zn(2+) in the presence of TPEN, both under intra- and extracellular conditions and is superior to other Mg(2+) probes which suffer from selectivity of Mg(2+) over Ca(2+) or Zn(2+). Furthermore the dissociation constant (Kd = 6.60 μM) of the Mg(2+)-() complex is far lower than the so far reported Mg(2+) probes which fall in the mM range.