作者:Christopher E. Anson、Tina J. Baldwin、Colin S. Creaser、Mark A. Fey、G. Richard Stephenson
DOI:10.1021/om950589o
日期:1996.3.5
Tricarbonylmetal pi-complexes of unsaturated organic ligands containing CO2H, OH, and NH2 substituents are used as FTIR-readable molecular probes of solution pH. Wavenumber shifts in the nu(sym)(CO) and nu(asym)(CO) bands in the FTIR spectra of the complexes [(eta(4)-CH3-CH=CHCH=CHC O2H)Fe(CO)(3)], [(eta(4)-CH3CH=CHCH=CHCO2H)Fe(CO)(2)(PPh(3))], [(eta(6)-(CH5)-H-6-CO2H)Cr(CO)(3)], [(eta(6)-o-C6H4(CO2H)(2))Cr(CO)(3)], [(eta(6)-C6H5NH2)Cr(CO)(3)], [(eta(6)-p-CH3C6H4OH)-Cr(CO)(3)], and [(eta(6)-p-CH3O2CC6H4OH)Cr(CO)(3)], resulting from deprotonation or protonation of the complexes, can be correlated with the pH of the solution, enabling straightforward spectroscopic readout of pH. It is shown that, by appropriate choice of pH-sensitive functional group, a complex can be selected to respond over a particular pH range and that the pH response can be fine-tuned by the presence of other substituents on the organic unit. The narrow bandwidths of the nu(CO) vibrational modes allow the simultaneous use of more than one such complex in a solution. This approach, which we term the use of ''dual-sensor'' systems, has several advantages over single sensors, and its potential in the analysis of multianalyte systems is described.