Silica cross-linked nanoparticles encapsulating a phenothiazine-derived Schiff base for selective detection of Fe(III) in aqueous media

This work demonstrates a luminescent chemosensor based on silica cross-linked micellar nanoparticles (SCMNPs) designed by encapsulating a phenothiazine-derived Schiff base, (4E)-4-((10-dodecyl-10H-phenothiazin-7-yl)methyleneamino)-1,2-dihydro-1,5-dimethyl-2-phenylpyrazol-3-one (EDDP), for the selective detection of Fe3+. The encapsulation of EDDP inside SCMNPs (EDDP–SCMNPs) can avoid the metal (Fe3+/Fe2+)-promoted hydrolysis of EDDP and, thus, exhibit highly selective determination of Fe3+. The electron transfer (ET) from EDDP in the core to Fe3+ adsorbed on the shell of EDDP–SCMNPs was verified using UV-vis absorption, fluorescent emission and 3D fluorescence spectra. Moreover, EDDP–SCMNPs showed no sensing ability of Fe2+ due to the weak electron-accepting ability of Fe2+. Significantly, because of their ultrasmall size, nontoxicity, good water solubility and biocompatibility, EDDP-SCMNPs have potential applications in biological systems.