Polymer-supported pH sensors based on hydrophobically bound luminescent ruthenium(II) complexes

A new luminescence intensity-based sensor-polymer support system is described. The pH-sensitive element is [Ru(phen)(2)[phen(OH)(2)]](2+) or [Ru(Ph(2)phen)(2)[phen(OH)(2)]](2+) (phen = 1,10-phenanthroline, Ph(2)phen = 4,7-diphenyl-1,10-phenanthroline, and phen(OH)(2) = 4,7-dihydroxy-1,10-phenanthroline) immobilized on a polymer built from a four-function cyclic methyl siloxane ring polymer having (SiRCH3O)(4) units with poly(ethylene oxide) cross-linkers. Hydrophobic binding of the sensor to the polymer is used to avoid the need for covalent chemistry. These sensor systems have a usable sensitivity over the 2-8 pH range, but are most usable in the 2-6 pH range. Response times for thick films (250 mu M) are rapid (several minutes).