Preparation and Self-assembly of Chiral Porphyrin Diads on the Gold Electrodes of Quartz Crystal Microbalances: A Novel Potential Approach to the Development of Enantioselective Chemical Sensors

摘要

Porphyrin diad 1 was synthesized by reaction of the acyl chloride of porphyrin 2 and trans-1,2-dithiane-4,5-diol. The Co complex of this diad was studied as a potential enantioselective receptor for chiral recognition in solution and in the solid state. In solution both enantimers of limonene indue significant changes in the visiblel and circular dichroism (CD) spectra of [Co_2(1)], while a different behavior is observed in the case of the enantiomeric pair of trans-1,2-diaminocyclohexane. A different efficiency of [Co_2(1)] chiral recogniton is obtained for these compounds, with a remarkable degree of enantiodiscriminatin observed in the case of limonene. Self-assembled mono-layers of [Co_2(1)] were doposited onto the gold electrodes of quartz crystal microbalances to be used as sensing materials of nanogravimetric sensors operating in the gas phase. The enantio-discrimination properties of these sensors towards the enantiomeric pairs of chiral analytes have been studied. While in the case of analytes bearing donor ligand atoms we did not observe a remarkable enantioselectivity, a significant degree of chiral discrimination was observed in the case of limonene; this result is particularly encouring for the potential development of enantioselective chemical sensors for use in an array configuration.