Water-soluble poly(p-phenylene) incorporating methoxyphenol units: Highly sensitive and selective chemodosimeters for hypochlorite

A series of water-soluble poly(p-phenylene)s (PPPs), named N-PPPx (x = 10, 25 and 50), were directly synthesized by Suzuki coupling in aqueous solution. The structures of the polymers were characterized by 1H NMR and elemental analysis. The polymers exhibit similar absorption and emission spectra with three absorption maxima at ca. 205, 290 and 350 nm, and emission maximum at 420 nm in phosphate buffer saline (PBS) solution. Upon addition of hypochlorite, N-PPPx shows a decrease of absorption band at ca. 350 nm and a fluorescent quenching. Compared to their model compound PMOPP, N-PPPx shows a significantly amplified fluorescent quenching. Moreover, the Ksv is decreased with the increasing content of methoxyphenol moieties in N-PPPx. In view of the sensitivity and selectivity, N-PPP10 and N-PPP25 are very promising polymeric fluorescent probes to hypochlorite under the aqueous condition.