Preparation of the 2,2′-biimidazole-based hypercrosslinked polymers by bottom-up synthetic strategy and their application for adsorping and fluorescence sensing 2,4-dinitrophenol

Abstract

The 2,2′-biimidazole-based hypercrosslinked polymers (2,2′-biimidazole-based HCPs, BIMM-3 and BIMM-4) were prepared by the synthetic strategy of one-pot bottom-up with nitrogen-rich 2,2′-biimidazole and triiodomethane or tetra-iodine methane for the first time. This new strategy offers the resulting HCPs presented nitrogen-rich and electron-rich. The as-synthesized 2,2′-biimidazole-based HCPs exhibit high iodine uptake capacities up to 8.04 and 4.57 g g-1, representing efficient adsorbents for wider environmental applications. The main reason for chemical sorption happening in 2,2′-biimidazole-based HCPs. Furthermore, BIMM-3 and BIMM-4 can sense nitroaromatic compounds (NACs, such as 2,4-dinitrophenol, DNP) with high quenching constants (Ksv) of 5.69 × 104 and 4.71 × 104 L mol-1 and low limits of detection (LODs) of 5.27 × 10-9 and 6.37 × 10-9 mol L-1. The quenching mechanisms of the 2,2′-biimidazole-based HCPs by DNP include both electron transfer process and resonance energy transfer process. Our work provided promising conclusions for HCPs as adsorbents and sensors for the capture of iodine and the detection of DNP for environmental remediation applications.