Absorption competition quenching mechanism of porous covalent organic polymer as luminescent sensor for selective sensing Fe3+

Developing luminescent sensors for highly selective detecting Fe3+ is a very important topic, because Fe3+ plays a key role in human's living environment. In this work, we use tetrakis (p-broMophenyl) methane as a monomer, and 4,4'- Dibromobiphenyl, 9,10-Dibromoanthracene, and 1,4-dibromonaphthalene as another monomer to synthesize three porous luminescent covalent-organic polymers (COPs) by Ni-catalyzed Yamamoto reaction respectively. Results indicate that these COPs exhibit excellent selectivity and sensitivity for detecting Fe3+ in 10 wt% ethanol aqueous solutions. By using the three COPs as representative sensors, we reveal the absorption competition quenching (ACQ) mechanism of the COPs for sensing Fe3+, i.e., the absorption spectrum overlap between the COPs and analytes leads to a competition of absorption of the light source between the analyte and the COP material, which causes the luminescence quenching of the COPs in detecting analytes. For all cases studied here, the ACQ mechanism takes effect. It is expected that the ACQ mechanism provided here can be used as an efficient strategy to design the new luminescent sensors for applications of interest.