Highly Luminescent Microporous Organic Polymer with Lewis Acidic Boron Sites on the Pore Surface: Ratiometric Sensing and Capture of F⁻ Ions

Abstract

Reversible and selective capture/detection of F(-) ions in water is of the utmost importance, as excess intake leads to adverse effects on human health. Highly robust Lewis acidic luminescent porous organic materials have potential for efficient sequestration and detection of F(-) ions. Herein, the rational design and synthesis of a boron-based, Lewis acidic microporous organic polymer (BMOP) derived from tris(4-bromo-2,3,5,6-tetramethylphenyl)boron nodes and diethynylbiphenyl linkers with a pore size of 1.08 nm for selective turn-on sensing and capture of F(-) ion are reported. The presence of a vacant pπ orbital on the boron center of BMOP results in intramolecular charge transfer (ICT) from the linker to boron. BMOP shows selective turn-on blue emission for F(-) ions in aqueous mixtures with a detection limit of 2.6 μM. Strong B-F interactions facilitate rapid sequestration of F(-) by BMOP. The ICT emission of BMOP can be reversibly regenerated by addition of an excess of water, and the polymer can be reused several times.

Trends and challenges for microporous polymers

“…186 Moreover, combining donor and acceptor moieties within one material can yield interesting electronic properties for optical applications or sensing. The separate functionalities can be combined in one monomer to create an intrinsic function, which is then polymerized, or an alternating copolymerization of building blocks with contrasting functionality can polymerized to synergistically enhance each other, with an ''emerging function''.…”

A Novel Zr‐MOF as Fluorescence Turn‐On Probe for Real‐Time Detecting H2S Gas and Fingerprint Identification

“…Compared to the fluorescence turn‐off probe, the fluorescence turn‐on probes show many advantages, and can avoid the wrong response to sensing signals and more easily identified in a dark background. Several types of fluorescence turn‐on probes have been reported, including metal–organic frameworks (MOFs), covalent organic materials, carbon dots, and small molecule fluorescent probes . Compared to other fluorescent probes, MOF‐based fluorescent probes have received more and more attention due to their intrinsic properties (e.g., adjustable structures, tunable pore size, and different fluorescent emission mechanism).…”

In Situ Formation of Frustrated Lewis Pairs in a Water‐Tolerant Metal‐Organic Framework for the Transformation of CO2

“…For SION-105,t he introduction of F À leads to the change of its emission properties. [26][27][28] Theluminescence emission of the Eu 3+ ions within SION-105 is induced by the antenna effect, in which the tctb 3À ligands absorb excitation photons and transfer the energy to the emissive levels of Eu 3+ .T he interaction between the Lewis acidic Batoms of tctb 3À and the Lewis basic F À anions leads to the formation of [B···F À ]pairs creating non-radiative pathways,w hich result in the quenching of the Eu 3+ emission. [29] When SION-105 was immersed in an acetonitrile-water mixture with excess of NaF (30 equiv compared to B) for 1hour,i ts red luminescence emission is quenched, indicative that the Bs ites are blocked by the F À ions (Supporting Information, Figure S10).…”