Novel thermo and ion-responsive copolymers based on metallo-base pair directed host-guest complexation for highly selective recognition of Hg2+ in aqueous solution.

The development of materials with highly selective recognition towards Hg2+ is of great significance in environmental monitoring. Herein, a novel thermo-responsive copolymer with Hg2+ recognition property is prepared via thermally-initiated copolymerization of 5′-O-Acryloyl 5-methyl-uridine (APU) and N -isopropylacrylamide (NIPAM). The chemical structure and stimuli-sensitive properties of poly(N -isopropylacrylamide- co -5-methyl-uridine) (P(NIPAM- co -APU)) linear polymers and hydrogel are thoroughly investigated. At the supramolecular level, P(NIPAM- co -APU) linear polymers could respond to both temperature and Hg2+ stimuli with highly selective recognition towards Hg2+ over other 18 metal ion species (at least 5 fold difference) and common anions. Upon capturing Hg2+ by APU units as host metal receptors, the lower critical solution temperature (LCST) of P(NIPAM- co -APU, PNU-7 and PNU-11) linear polymers are significantly shifted more than 10 °C due to the formation of stable APU -Hg2+- APU directed host-guest complexes. Accordingly, at the macroscopic level, P(NIPAM- co -APU) hydrogel display selective and robust recognition of Hg2+ under optimum conditions, and its maximum Hg2+ uptake capacity was 33.1 mg g−1. This work provides a new option for Hg2+ recognition with high selectivity, which could be facilely integrated with other smart systems to achieve satisfactory detection of environmental Hg2+. [Display omitted] • Thermo and ion-responsive polymers were synthesized by copolymerization of APU and NIPAM. • The linear copolymers have a highly selective recognition of mercury ions. • The different stabilities of divers metal-mediated base-pairs were rationalized by theoretical calculation. • The hydrogels can be recycled for highly selective recognition of mercury ions. [ABSTRACT FROM AUTHOR]