Molecular sensing behavior of the first Mn(I)-compound of di-2-pyridylketone- p-nitrophenylhydrazone (dpknph), fac-[Mn(CO) 3(dpknph)Br]

• Published in: Inorganica Chimica Acta Vol. 358; no. 6; pp. 1835 - 1840
• Main Authors: Bakir, Mohammed, Green, Orville, Gyles, Colin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30-03-2005
• Subjects: Carbonyl; Di-2-pyridyl ketone; Hydrazones; Manganese; Sensors; Hydrazones; Sensors; Carbonyl; Di-2-pyridyl ketone; Manganese
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2004.12.050

Optical and thermodynamic measurement on
fac-Mn(CO)
3(dpknph)Br in polar solvents reveal reversible interconversion between two intense electronic states and use as an optical sensor. Group 12 metal ions in concentration as low as 1.0
×
10
−9
M can be detected and determined using
fac-Mn(CO)
3(dpknph)Br in polar solvents.
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 π–π* (dpk), followed by dpk
→
nitro intraligand charge transfer transition (ILCT), mixed with metal ligand charge transfer transition (MLCT) due to
d
π
(
Mn
)
→
π
(
dpk
)
∗
. 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 NaBF
4. Changes in enthalpy (Δ
H
ø) of +14.0 and −12.1
kJ
mol
−1, entropy (Δ
S
ø) of +28.65 and −64.30
J
mol
−1
K
−1, and free energy (Δ
G
ø) 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 NaBH
4.