Covalent organic polymer framework with C–C bonds as a fluorescent probe for selective iron detection

A new carbon–carbon bonded nanoporous polymer network was synthesized via efficient and catalyst free Knoevenagel-like condensation polymerization in near quantitative yields. The obtained polymer network, Covalent Organic Polymer – COP-100 possesses strong fluorescent properties and designed solubility in polar aprotic solvents, which shows promise for use as a metal-sensing material in solution. COP-100 exhibited high selectivity towards Fe 2+ and Fe 3+ in the presence of other common metal cations (Al 3+ , Ag + , Cd 2+ , Co 2+ , Cr 3+ , Cu 2+ , Hg 2+ , Mg 2+ , Mn 2+ , Na + , Ni 2+ , Zn 2+ ) as the fluorescence of the polymer was significantly quenched even at very low concentrations. In the range from 2.5 × 10 −6 to 2 × 10 −4 M, a linear fluorescence emission response with equipment limited detection minimum of 2.13 × 10 −7 M and 2.45 × 10 −7 M for Fe 2+ and Fe 3+ , respectively, was observed. These results suggest that COP-100 is a promising material as a selective fluorescence sensor for iron ions.