Powders to Thin Films: Advances in Conjugated Microporous Polymer Chemical Sensors.

Chemical sensing of harmful species released either from natural or anthropogenic activities is critical to ensuring human safety and health. Over the last decade, conjugated microporous polymers (CMPs) have been proven to be potential sensor materials with the possibility of realizing sensing devices for practical applications. CMPs found to be unique among other porous materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) due to their high chemical/thermal stability, high surface area, microporosity, efficient host-guest interactions with the analyte, efficient exciton migration along the π-conjugated chains, and tailorable structure to target specific analytes. Several CMP-based optical, electrochemical, colorimetric, and ratiometric sensors with excellent selectivity and sensing performance were reported. This review comprehensively discusses the advances in CMP chemical sensors (powders and thin films) in the detection of nitroaromatic explosives, chemical warfare agents, anions, metal ions, biomolecules, iodine, and volatile organic compounds (VOCs), with simultaneous delineation of design strategy principles guiding the selectivity and sensitivity of CMP. Preceding this, various photophysical mechanisms responsible for chemical sensing are discussed in detail for convenience. Finally, future challenges to be addressed in the field of CMP chemical sensors are discussed.

Polar functional groups anchored to a 2D MOF template for the stabilization of Pd(0) nps for the catalytic C-C coupling reaction.

A 2D porous MOF, {[Cu(1,2,3-btc)(bpe)(H2O)]·H2O}n (1), has been synthesized using a mixed linker system. The structural determination showed non-coordinated carboxylate groups decorating the pore surface. The desolvated MOF (1a) with pendant carboxylate groups was used as a template for the stabilization of Pd nps (2-3 nm) and the resulting composite Pd(0)@1a showed efficient catalytic activity for the Suzuki-Miyaura C-C coupling reaction.

Regulating Charge-Transfer in Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution.

Bandgap engineering in donor-acceptor conjugated microporous polymers (CMPs) is a potential way to increase the solar-energy harvesting towards photochemical water splitting. Here, the design and synthesis of a series of donor-acceptor CMPs [tetraphenylethylene (TPE) and 9-fluorenone (F) as the donor and the acceptor, respectively], F0.1 CMP, F0.5 CMP, and F2.0 CMP, are reported. These CMPs exhibited tunable bandgaps and photocatalytic hydrogen evolution from water. The donor-acceptor CMPs exhibited also intramolecular charge-transfer (ICT) absorption in the visible region (λmax =480 nm) and their bandgap was finely tuned from 2.8 to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also showed emissions in the 540-580 nm range assisted by the energy transfer from the other TPE segments (not involved in charge-transfer interactions), as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer was also tuned from green to red. Photocatalytic activities of the donor-acceptor CMPs (F0.1 CMP, F0.5 CMP, and F2.0 CMP) are greatly enhanced compared to the 9-fluorenone free polymer (F0.0 CMP), which is essentially due to improved visible-light absorption and low bandgap of donor-acceptor CMPs. Among all the polymers F0.5 CMP with an optimum bandgap (2.3 eV) showed the highest H2 evolution under visible-light irradiation. Moreover, all polymers showed excellent dispersibility in organic solvents and easy coated on the solid substrates.