Optosensing properties of fac-Re(CO)3(dpknph)Cl (dpknph=di-2-pyridyl ketone p-nitrophenyl hydrazone) toward chemotactic N-formylamino acids

Optical measurements on fac-Re(CO)(3)(dpknph)Cl in polar non-aqueous solvents in the presence and absence of NaBH4/KPF6 revealed reversible interconversion between the high (beta-) and low (alpha-) energy electronic states of fac-Re(CO)(3)(dpknph)Cl. The reversibility of these interactions and the disturbance of the equilibrium distribution of the low (alpha-) and high (beta-) energy electronic state upon addition of NaBH4/KPF6 mark improvement in the optosensing properties of fac-Re(CO)(3)(dpknph)Cl. The optical behavior of fac-Re(CO)(3)(dpknph)Cl in the presence and absence of the L-methionine and chemotactic N-formylamino acids: N-formyl-L-methionine (NFM), N-formyl-L-glycine (NFG) and N-formyl-L-phenylalanine (NFP) shows the alpha- and P-electronic states of fac-Re(CO)(3)(dpknph)Cl to be insensitive to L-methinonine and highly sensitive to N-formylamino acids. N-formylamino acids in concentrations < 1.0 x 10(-5) M can be determined using the optical sensor fac-Re(CO)(3)(dpknph)Cl in non-aqueous polar solvents. The optosensing power of fac-Re(CO)(3)(dpknph)Cl towards N-formylamino acids depends on the concentration and polarity of the side chain of the amino acids and increases in the following order: NFM > NFG > NFP. (C) 2002 Elsevier Science B.V. All rights reserved.