TY - JOUR
T1 - Synthesis, and molecular sensing behavior of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl], dpksc = di-2-pyridyl ketone semicarbazone
AU - Bakir, Mohammed
AU - Brown, Ordel
N1 - Funding Information:
We acknowledge Ms. Tony Johnson for NMR measurements and the University of the West Indies for funding of this research.
PY - 2013/1/30
Y1 - 2013/1/30
N2 - When [Re(CO)5Cl] was allowed to react with di-2-pyridyl ketone semicarbazone hydrochloride (dpksc.HCl) in refluxing toluene, fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] was isolated. The identity of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] was elucidated from the results of its elemental analysis and confirmed using a number of spectroscopic measurements. Spectroscopic measurements done on non-aqueous solvents divulged sensitivity of fac-[Re(CO)3(κ2-N, N-dpksc)Cl] to changes in its surroundings. 1H NMR studies revealed significant solvent dependence as manifested by the chemical shift variations; the exchange of the amine protons with solvent deuterium in CDCl3 and d6-acetone; the temperature dependence of the chemical shifts of the amine and amide protons and insignificant temperature dependence of the aromatic proton. The electronic absorption spectra of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] measured on non-aqueous solvents disclosed two high energy intra-ligand charge transfer (ILCT) transitions. Optical measurements performed on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] in the presence of bases and acids showed the appearance and disappearance of a low energy ILCT electronic transitions and established reversible inter-conversion between fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] and its conjugate base, fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl]-. Thermo-optical measurements done on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] disclosed the absence of thermal acid-base inter-conversion between fac-[Re(CO)3(κ2- N,N-dpksc)Cl] and fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl] - and established reversible electronic transfer between the high energy electronic transitions of fac-[Re(CO)3(κ2-N, N-dpksc)Cl]. Optosensing measurements done on protophilic solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed acids and bases in concentrations as low as 1.00 × 10-10 M can be detected and determined using protophilic solutions of of fac-[Re(CO)3(κ 2-N,N-dpksc)Cl]. Electrochemical measurements on dmf solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed irreversible electrochemical redox process and electrochemically generated product waves pointing to the instability of fac-[Re(CO)3(κ2-N,N- dpksc)Cl] to redox transformations.
AB - When [Re(CO)5Cl] was allowed to react with di-2-pyridyl ketone semicarbazone hydrochloride (dpksc.HCl) in refluxing toluene, fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] was isolated. The identity of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] was elucidated from the results of its elemental analysis and confirmed using a number of spectroscopic measurements. Spectroscopic measurements done on non-aqueous solvents divulged sensitivity of fac-[Re(CO)3(κ2-N, N-dpksc)Cl] to changes in its surroundings. 1H NMR studies revealed significant solvent dependence as manifested by the chemical shift variations; the exchange of the amine protons with solvent deuterium in CDCl3 and d6-acetone; the temperature dependence of the chemical shifts of the amine and amide protons and insignificant temperature dependence of the aromatic proton. The electronic absorption spectra of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] measured on non-aqueous solvents disclosed two high energy intra-ligand charge transfer (ILCT) transitions. Optical measurements performed on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] in the presence of bases and acids showed the appearance and disappearance of a low energy ILCT electronic transitions and established reversible inter-conversion between fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] and its conjugate base, fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl]-. Thermo-optical measurements done on protophilic solutions of fac-[Re(CO) 3(κ2-N,N-dpksc)Cl] disclosed the absence of thermal acid-base inter-conversion between fac-[Re(CO)3(κ2- N,N-dpksc)Cl] and fac-[Re(CO)3(κ2-N,N-dpksc-H)Cl] - and established reversible electronic transfer between the high energy electronic transitions of fac-[Re(CO)3(κ2-N, N-dpksc)Cl]. Optosensing measurements done on protophilic solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed acids and bases in concentrations as low as 1.00 × 10-10 M can be detected and determined using protophilic solutions of of fac-[Re(CO)3(κ 2-N,N-dpksc)Cl]. Electrochemical measurements on dmf solutions of fac-[Re(CO)3(κ2-N,N-dpksc)Cl] showed irreversible electrochemical redox process and electrochemically generated product waves pointing to the instability of fac-[Re(CO)3(κ2-N,N- dpksc)Cl] to redox transformations.
KW - Di-2-pyridyl ketone semicarbazone
KW - Electrochemistry
KW - Rhenium
KW - Sensors
KW - Spectroscopy
KW - Synthesis
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U2 - 10.1016/j.molstruc.2012.07.047
DO - 10.1016/j.molstruc.2012.07.047
M3 - Article
AN - SCOPUS:84865542338
VL - 1032
SP - 118
EP - 125
JO - Journal of Molecular Structure
JF - Journal of Molecular Structure
SN - 0022-2860
ER -