Covalent organic frameworks (COFs) are an attractive class of crystalline, porous materials because their reticular chemistry allows frameworks to be synthesized in a predictable manner. As a result of this defining characteristic, the past decades have witnessed considerable efforts to demonstrate unique pore shapes and sizes; however, less attention is often given to atomistic level structural changes. To further understand the relationship of a COF’s structure and its unique properties, this work provides a foundational study exploring the relationship of structural isomer linkages in two COFs, TAPA–PDA COF and IISERP-COF2. These imine-based COFs were extensively studied and compared with respect to their synthetic conditions, framework properties, phase reversibility, optical properties, and surface energy. Our results suggest that compared to IISERP-COF2, the TAPA–PDA COF has stronger phase change reversibility and significant red shifting of the UV–vis absorption and fluorescence and exhibits hydrophilicity. These findings provide evidence that careful consideration of monomer pairs is necessary when designing materials because these minor structural changes can lead to vastly diverging properties.

Ten methylated-meso-phenyl-BODIPY dyes with varying iodine content were synthesized and studied using experimental and theoretical methods to examine how iodine substitution and loading influence the excited-state dynamics of the chromophores.

Optical oxygen sensors have many promising qualities but rely on excitation by violet or blue wavelengths that suffer from high levels of scattering and absorption in biological tissues. Here we demonstrate an alternative method using 980nm near-infrared light to initially stimulate ceramic upconverting nanoparticles (UCNPs) contained within a novel form, electrospun core-shell fibers. The emission of the UCNPs excites a molecular optical oxygen sensor, the subsequent phosphorescent emission being dynamically quenched by the presence of molecular oxygen. The potential for use of such an energy transfer within electrospun fibers widely used in biological applications is promising. However, current knowledge of such 'handshake' interactions is limited. Fiber-based carriers enabling such optical conversions provide unique opportunities for biosensing as they recapitulate the topography of the extracellular matrix. This creates a wide array of potential theranostic, fiber-based applications in disease diagnosis/imaging, drug delivery and monitoring of therapeutic response. Using a fiber-based vehicle, we observed gaseous oxygen sensing capabilities and a linear Stern-Volmer response allowing highly accurate calibration. Configurational aspects were also studied to determine how to maximize the efficiency of this 'handshake' interaction.