Bakir, Mohammed A ; Green, O. ; Gyles, C
Author Affiliation, Ana.
Department of Chemistry
Molecular sensing behavior of the first Mn(I)-compound of di-2-pyridylketone-p-mitrophenylhydrazone (dpknph), fac-[Mn(CO)3-(dpknph)Br]
Inorganica Chimica Acta
Date of Publication
The reaction between [Mn(CO)5Br] and di-2-pyridylketone-p-nitrophenylhydrazone (dpknph) in diethyl ether under ultrasonic conditions gave fac-[Mn(CO)3(dpknph)Br] in good yield. Optical and thermodynamic measurements on fac-[Mn(CO)3(dpknph)Br] in non-aqueous polar solvents revealed reversible interconversion between two intense charge transfer absorption bands due to p–p* (dpk), followed by dpk ? nitro intraligand charge transfer transition (ILCT), mixed with metal ligand charge transfer transition (MLCT) due to . In non-polar solvents, a single absorption band appeared. Extinction coefficients of 46 200 ± 2000 and 28 400 ± 2000 M-1 cm-1 were calculated in DMSO for the low- and high-energy electronic states of fac-[Mn(CO)3(dpknph)Br] using excess NaBF4. Changes in enthalpy (?Hø) of +14.0 and -12.1 kJ mol-1, entropy (?Sø) of +28.65 and -64.30 J mol-1 K-1, and free energy (?Gø) of +5.48 and +7.08 kJ mol-1 at 298 K were calculated for the interconversion between the high and low energy electronic states of fac-[Mn(CO)3(dpknph)Br]. These results allow for the use of these systems (fac-[Mn(CO)3(dpknph)Br] and surrounding solvent or solute molecules) as optical sensors for a variety of physical and chemical stimuli that include metal ions. Group 12 metal ions in concentrations as low as 1.00 × 10-9 M can be detected and determined using fac-[Mn(CO)3(dpknph)Br] in dmso in the presence and absence of NaBH4....