A Fluorescent Dissymmetric Thiosemicarbazone Ligand Containing a Hydrazonequinoline Arm and Its Complexes with Cadmium and Mercury

Abstract

A new dissymmetric thiosemicarbazone ligand containing a hydrazonequinoline arm, H2AMeTsQ, and its chloride salt, [H3AMeTsQ]Cl, were synthesized. Nine new complexes of cadmium and mercury with different structural characteristics were obtained under different reaction conditions as the ligand charge can be controlled by varying the amount of base. 113Cd and 199Hg NMR spectroscopy together with X‐ray diffraction indicated that the complexes form monomeric and dimeric structures and even a coordination polymer. Fluorescence spectroscopy showed that both protonated and neutral forms of the ligand were fluorescent as well as some of their cadmium and mercury derivatives. The fluorescence intensity decreased upon complexation and in some complexes a shift of the emission maximum was also observed.

Zinc and mercury complexes of benzil bis(4-methyl-3-thiosemicarbazone)

“…4). The shift in chloroform is similar to those observed in other thiosemicarbazonate complexes containing a penta-coordinated mercury atom [22,34,36], and agrees with a dinuclear structure with a sulfur atom acting as a bridge between to metal centers, in which the mercury atom is penta-coordinated. This bridge should be broken in DMSO-d 6 since the signal is shifted to lower field, suggesting a lower coordination number.…”

“…Unlike of copper and zinc complexes obtained with benzil bis (thiosemicarbazone), in which the reaction under reflux and in the absence of basic medium yielded complexes containing a singly deprotonated ligand [15,21], in the title reactions it is no possible to induce monodeprotonation. In the reactions with dissymmetric thiosemicarbazones, both single and double deprotonation could be controlled [16,22], due to the different acidity of the hydrazinic hydrogens.…”

“…Following our interest in the coordinating behavior of symmetric and dissymmetric bis(thiosemicarbazone) ligands with different metals with potential biological applications such as nickel [14], copper [15], zinc [14,16] or tin [17] or with demonstrated toxicity as cadmium [14,18,19], lead [20] and mercury [21,22], in this paper we report an extension of our previous work with the symmetric ligand benzil bis(4-methyl-3-thiosemicarbazone), LMe 2 H 4 . This ligand has shown a versatile behavior with toxic metals such as PbPh 2 2+ and cadmium(II) and, depending of the pH, it acts as neutral or doubly deprotonated ligand.…”

Synthesis and crystal structure of a new 2D supramolecular Cd(II) complex with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone ligand

“…The Cd(II) atom, as a IIB group metal ion, has a 4d 10 electron configuration and displays flexible coordination numbers (Sun et al, 2005;Hu and Li, 2010;Nie et al, 2010;Calatayud et al, 2013;Sharif and Najafi, 2013). In addition, some Cd(II) complexes show good fluorescent (Nie et al, 2010;Pathak et al, 2012;Calatayud et al, 2013) and antimicrobial (Zaky et al, 2012) properties. Herein, we report a new Cd(II) compound with PMBP ligand, [Cd(PMBP) 2 (CH 3 OH) 2 ] (1) and its properties.…”

Copper complexes with dissymmetrically substituted bis(thiosemicarbazone) ligands as a basis for PET radiopharmaceuticals: control of redox potential and lipophilicity

“…45 Cyclisation 25,26,46,47 of the intermediate may also occur. Dissymmetric bis(thiosemicarbazone) proligands have been reported in which one side arm is modified to improve water solubility (using a carbohydrate 48 or sulfonate 39 ), introduce fluorescence 49 or radiolabel with fluorine-18. 50 These proligands were derived from a dissymmetric bis(thiosemicarbazone) in which one thiosemicarbazide arm is a thiocarbohydrazide 40,[42][43][44]51 (Fig.…”