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Publication Type
Journal Article
UWI Author(s)
Author, Analytic
Bakir, Mohammed A.; Brown, O.
Author Affiliation, Ana.
Department of Chemistry
Article Title
Molecular structure and optosensing behaviour of di-2-pyridyl ketone benzoylhydrazone in nonaqueous solvents
Medium Designator
n/a
Connective Phrase
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Journal Title
Journal of molecular structure
Translated Title
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Reprint Status
Refereed
Date of Publication
2002
Volume ID
609
Issue ID
1-3
Page(s)
129-136
Language
n/a
Connective Phrase
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Location/URL
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ISSN
n/a
Notes
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Abstract
Crystals of di-2-pyridyl ketone benzoylhydrazone (dpkbh) obtained from a dimethylsulfoxide (DMSO) solution of dpkbh are in the monoclinic space group, P21/c. Structural analysis reveals anti-parallel, non-planar, one-dimensional tapes of dpkbh with a network of intra- and intermolecular hydrogen bonds. Optical measurements on dpkbh in polar non-aqueous solvents revealed the presence of interlocked low-(a-) and high-(b-) energy intraligand charge-transfer electronic states may be due to dpk pp* followed by dpk to benzoyl charge-transfer. The equilibrium distribution of the low-(a-) and high-(b-) energy electronic states is solvent dependent, controlled by the hydrogen bonding capacity of surrounding solvent molecules. The interplay between the a- and b-conformations of dpkbh allowed calculations of their extinction coefficients by forcing the equilibrium to shift to one conformation using chemical stimuli. In N,N-dimethylformamide (DMF), extinction coefficients of 45,0002000 and 15,0002000 M-1 cm-1 were calculated for the a- and b-conformations of dpkbh at lmax, respectively, when excess acid was added to a DMF solution of dpkbh. The weak bond energies of the hydrogen bonds, the reversibility and the sensitivity of the high- and low-energy electronic states to their surroundings in polar non-aqueous solvents allow for the use of this system as molecular sensor for a variety of stimuli that include metal ions, acids and bases. Metal ions in concentrations <10-7 M can be detected and determined using this system (dpkbh and surrounding solvent molecules).....
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