TY - JOUR
T1 - Molecular structure and optosensing behavior of di-2-pyridyl ketone benzoylhydrazone in non-aqueous solvents
AU - Bakir, Mohammed
AU - Brown, Ordel
N1 - Funding Information:
We acknowledge funding from The University of the West Indies and Inter-America Development Bank.
PY - 2002/5/30
Y1 - 2002/5/30
N2 - Crystals of di-2-pyridyl ketone benzoylhydrazone (dpkbh) obtained from a dimethylsulfoxide (DMSO) solution of dpkbh are in the monoclinic space group, Pl/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-(α-) and high-(β-) energy intraligand charge-transfer electronic states may be due to dpk π-π* followed by dpk to benzoyl charge-transfer. The equilibrium distribution of the low-(α-) and high-(β-) energy electronic states is solvent dependent, controlled by the hydrogen bonding capacity of surrounding solvent molecules. The interplay between the α- and β-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 45,000 ± 2000 and 15,000 ± 2000 M-1 cm-1 were calculated for the α- and β-conformations of dpkbh at λmax, 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).
AB - Crystals of di-2-pyridyl ketone benzoylhydrazone (dpkbh) obtained from a dimethylsulfoxide (DMSO) solution of dpkbh are in the monoclinic space group, Pl/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-(α-) and high-(β-) energy intraligand charge-transfer electronic states may be due to dpk π-π* followed by dpk to benzoyl charge-transfer. The equilibrium distribution of the low-(α-) and high-(β-) energy electronic states is solvent dependent, controlled by the hydrogen bonding capacity of surrounding solvent molecules. The interplay between the α- and β-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 45,000 ± 2000 and 15,000 ± 2000 M-1 cm-1 were calculated for the α- and β-conformations of dpkbh at λmax, 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).
KW - Di-2-pyridyl ketone benzoylhydrazone
KW - Electronic absorption spectrum
KW - Optosensing
UR - http://www.scopus.com/inward/record.url?scp=0037198454&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037198454&partnerID=8YFLogxK
U2 - 10.1016/S0022-2860(01)00973-5
DO - 10.1016/S0022-2860(01)00973-5
M3 - Article
AN - SCOPUS:0037198454
SN - 0022-2860
VL - 609
SP - 129
EP - 136
JO - Journal of Molecular Structure
JF - Journal of Molecular Structure
IS - 1-3
ER -