Spectrophotometric and Polarographic Studies of Di-2-pyridyl ketone 2-thienoylhydrazone.

Zuhri, Ali Z. Abu; El-Shahawi, M. S.; Kamal, Mostafa; Al-Nuri, Mohamad; Hannoun, Mohamed

doi:10.1080/00032719408002640

Cited by 7 publications

(1 citation statement)

References 21 publications

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“…1 H-NMR studies in non-aqueous media confirmed the sensitivity of dpktch to changes in its surroundings and showed two isomers/conformations at low temperature; when the temperature increased one isomer predominates. Although the optosensing behavior of dpktch in aqueous media and the synthesis of two of its tin complexes and their bioactivities were reported over ten years ago, literature on the coordination chemistry of dpktch is scarce [26,27]. In a recent report we described the synthesis, characterization, and X-ray structural analysis of the first cadmium compound of dpktch, and in this report we describe the isolation, physico-chemical properties and structure of [ZnCl 2 ( 3 -dpktch)] and compare the results with those reported for [CdCl 2 ( 3 -dpktch)] [15].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Conry

Green

Mulder

2008

Journal of Coordination Chemistry

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When dpktch was reacted with ZnCl 2 in refluxing acetonitrile in air [ZnCl 2 ( 3 -dpktch)] was isolated in good yield. Infrared spectra suggest weaker binding of dpktch in [ZnCl 2 ( 3 -dpktch)] than in [CdCl 2 ( 3 -dpktch)]. 1 H-NMR studies in non-aqueous media show that [ZnCl 2 ( 3 -dpktch)] is sensitive to changes in its environment and exchanges its amide proton. Electronic absorption spectral measurements confirmed the sensitivity of [ZnCl 2 ( 3 -dpktch)] to changes in its surroundings and show inter-conversion between two intra-ligand-charge-transfer transitions (ILCT) at 330 AE 2 nm and 404 AE 2 associated with [ZnCl 2 ( 3 -dpktch)] and its conjugate base. Thermo-optical measurements in non-aqueous dmf and dmso show facile interconversion between [ZnCl 2 ( 3 -dpktch)] and its conjugate base, respectively. Also, it is shown that protonation of dmf by [ZnCl 2 ( 3 -dpktch)] is exothermic (standard enthalpy of protonation ÁH ¼ À40.7 AE 1.8 kJ mol À1 ), but endothermic for dmso (ÁH ¼ þ8.3 AE 1.5 kJ mol À1 ). Chemical stimuli in concentrations as low as 5.0 Â 10 À7 M can be detected and determined using [ZnCl 2 ( 3 -dpktch)] in non-aqueous media. X-ray crystallographic studies on a monoclinic, P2 1 /n single crystal of [ZnCl 2 ( 3 -dpktch)] confirmed the N,N,O-coordination of dpktch and revealed interdigitated units of [ZnCl 2 ( 3 -dpktch)] connected via a web of hydrogen bonds.

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Section: Introductionmentioning

confidence: 99%

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Conry

Green

Mulder

2008

Journal of Coordination Chemistry

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Cytotoxic iron chelators: characterization of the structure, solution chemistry and redox activity of ligands and iron complexes of the di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) analogues

et al. 2003

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Di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) and a range of its analogues comprise a series of monobasic acids that are capable of binding iron (Fe) as tridentate ( N, N, O) ligands. Recently, we have shown that these chelators are highly cytotoxic, but show selective activity against cancer cells. Particularly interesting was the fact that cytotoxicity of theHPKIH analogues is maintained even after complexation with Fe. To understand the potent anti-tumor activity of these compounds, we have fully characterized their chemical properties. This included examination of the solution chemistry and X-ray crystal structures of both the ligands and Fe complexes from this class and the ability of these complexes to mediate redox reactions. Potentiometric titrations demonstrated that all chelators are present predominantly in their charge-neutral form at physiological pH (7.4), allowing access across biological membranes. Keto-enol tautomerism of the ligands was identified, with the tautomers exhibiting distinctly different protonation constants. Interestingly, the chelators form low-spin (diamagnetic) divalent Fe complexes in solution. The chelators form distorted octahedral complexes with Fe(II), with two tridentate ligands arranged in a meridional fashion. Electrochemistry of the Fe complexes in both aqueous and non-aqueous solutions revealed that the complexes are oxidized to their ferric form at relatively high potentials, but this oxidation is coupled to a rapid reaction with water to form a hydrated (carbinolamine) derivative, leading to irreversible electrochemistry. The Fe complexes of theHPKIH analogues caused marked DNA degradation in the presence of hydrogen peroxide. This observation confirms that Fe complexes from theHPKIH series mediate Fenton chemistry and do not repel DNA. Collectively, studies on the solution chemistry and structure of theseHPKIH analogues indicate that they can bind cellular Fe and enhance its redox activity, resulting in oxidative damage to vital biomolecules.

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Molecular sensing behavior of di-2-pyridylketone-2-thenoylhydrazone (dpktah) in non-aqueous media

Gyles

2007

Journal of Molecular Structure

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Spectrophotometric and Polarographic Studies of Di-2-pyridyl ketone 2-thienoylhydrazone.

Cited by 7 publications

References 21 publications

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Cytotoxic iron chelators: characterization of the structure, solution chemistry and redox activity of ligands and iron complexes of the di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) analogues

Molecular sensing behavior of di-2-pyridylketone-2-thenoylhydrazone (dpktah) in non-aqueous media

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Spectrophotometric and Polarographic Studies of Di-2-pyridyl ketone 2-thienoylhydrazone.

Cited by 7 publications

References 21 publications

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl2 (η3-dpktch)] (η3-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl2 (η3-dpktch)] (η3-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Cytotoxic iron chelators: characterization of the structure, solution chemistry and redox activity of ligands and iron complexes of the di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) analogues

Molecular sensing behavior of di-2-pyridylketone-2-thenoylhydrazone (dpktah) in non-aqueous media

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Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)

Synthesis, spectroscopy, thermodynamics and structure of [ZnCl₂ (η³-dpktch)] (η³-dpktch = N,N,O- di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone)