Immobilization of a water insoluble iridium complex with organosilica nanoparticles for electrochemiluminescence sensing

We report on a novel strategy for electrochemiluminescent (ECL) chemical sensing by making use of an electrode modified with organosilica nanoparticles (OSiNPs) that are loaded with an iridium(III) complex Ir(pq)(2)(acac) (where pq stands for 2-phenylquinoline and acac stands for acetylacetonato). Three kinds of OSiNPs have been prepared by using vinyltrimethoxysilane, vinyltriethoxysilane, and phenyltrimethoxysilane, respectively, as the precursors. The OSiNPs were spherical in shape, uniform in size, and highly monodisperse in the aqueous phase. The luminescence properties of the Ir(III) complex remain unchanged after encapsulation. The ECL properties of the modified electrodes were evaluated by using 2-(dibutylamino) ethanol (DBAE) as the coreactant (analyte). The electrode prepared from phenyltrimethoxysilane as the precursor exhibited the best sensitivity for DBAE and gives a detection limit as low as 5.0 x 10(-9) mol L-1 and a linear range from 1.0 x 10(-8) to 1.0 x 10(-6) mol L-1.