Multiresponsive polysiloxane bearing photochromic spirobenzopyran for sensing pH changes and Fe3+ ions and sequential sensing of Ag+ and Hg2+ ions

Abstract

Abstract A spiropyran-appended polysiloxane (SP-Si) was synthesized and characterized. The photochromic SP-Si has good thermal stability and exhibits high fatigue resistance to light. SP-Si acts as a dual colorimetric and spectroscopic probe for determining multi-scale pH over a wide range of 1∼14, and for detection of Ag+ and Fe3+ ions. Based on the transformation from colorless SP-Si solution without absorption at 440 nm to brown SP-Si/Ag+ showing extremely strong absorption at 440 nm by addition of Ag+ ions and subsequent transformation from brown to colorless SP-Si/Ag+/Hg2+ with very weak absorption at 440 nm after addition of 1 equivalent of Hg2+ ions, SP-Si/Ag+ system serves as a dual colorimetric and spectroscopic probe for highly selective and sensitive detection of Hg2+ ions. The detection is not interfered by common competitive metal ions such as Na+, K+, Li+, Ni2+, Fe2+, Zn2+, Co2+, Sr2+, Cu2+, Al3+, Ce3+ and Cr3+. Applicability of SP-Si for real water sample analysis has been proved.