Following the advancements and diversification in synthetic strategies for porous covalent materials in the literature, the materials science community started to investigate the performance of covalent organic polymers (COPs) and covalent organic frameworks (COFs) in applications that require large surface areas for interaction with other molecules, chemical stability, and insolubility. Sensorics is an area where COPs and COFs have demonstrated immense potential and achieved high levels of sensitivity and selectivity on account of their tunable structures. In this review, we focus on those covalent polymeric systems that use fluorescence spectroscopy as a method of detection. After briefly reviewing the physical basis of fluorescence-based sensors, we delve into various kinds of analytes that have been explored with COPs and COFs, namely, heavy metal ions, explosives, biological molecules, amines, pH, volatile organic compounds and solvents, iodine, enantiomers, gases, and anions. Throughout this work, we discuss the mechanisms involved in each sensing application and aim to quantify the potency of the discussed sensors by providing limits of detection and quenching constants when available. This review concludes with a summary of the surveyed literature and raises a few concerns that should be addressed in the future development of COP and COF fluorescence-based sensors.

A direct electrocaloric effect (ECE) measurement system, based on a modified-differential scanning calorimeter (DSC), allowing the acquisition of both thermal (ECE, heat capacity) and electrical (P-E loops, leakage current) information simultaneously, was used to analyze 〈001〉-oriented PbMg1/3Nb2/3O3-30PbTiO3 single crystals. Different electric-field-induced phase transitions were identified on direct ECE measurements and confirmed by dielectric measurements. The strongest ECE (ΔTEC = 0.65 K) was measured for an applied electric field E = 10 kV/cm just above the temperature of depolarization. The direct ECE measurements were compared with indirect measurements obtained from dielectric polarization measurements versus electric field and temperature and a very good agreement was found. A region with negative ΔTEC was identified by both direct and indirect measurements. This phenomenon was attributed to the formation of a reversible field-induced phase transition towards a state with a different polar direction.