A simple and highly selective 2,2-diferrocenylpropane-based multi-channel ion pair receptor for Pb2+ and HSO4−

Abstract

A structurally simple, 2,2-diferrocenylpropane-based ion pair receptor 1 was synthesized and characterized by ¹H NMR, ¹³C NMR, HRMS, elemental analyses, and single-crystal X-ray diffraction. The ion pair receptor 1 showed excellent selectivity and sensitivity towards Pb²⁺ with multi-channel responses: a fluorescence enhancement (more than 42-fold), a notable color change from yellow to red, redox anodic shift (ΔE_1/2 = 151 mV), while HSO₄⁻ promoted fluorescence enhancement when Pb²⁺ or Zn²⁺ was bonded to the cation binding-site. ¹H NMR titration and density functional theory were performed to reveal the sensing mechanism based on photo-induced electron transfer (PET).