Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin-orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels-Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage.ope

Teaching Analytical Method Transfer through Developing and Validating Then Transferring Dissolution Testing Methods for Pharmaceuticals

Analytical method transfer (AMT) and dissolution testing are important topics required in industry that should be taught in analytical chemistry courses. Undergraduate students in senior level analytical chemistry laboratory courses at Kennesaw State University (KSU) and St. John Fisher College (SJFC) participated in development, validation, and transfer of two dissolution testing methods for pharmaceuticals. These experiments were transferred between the two schools and underwent method equivalency testing by a different set of undergraduate students to validate the AMT. Student learning outcomes addressed at both SJFC and KSU include (1) significant learning gains across all 3 years of the study; (2) confidence in method development, writing standard operating procedures, and laboratory transfer of validated methods; (3) increased understanding of AMT and dissolution testing; (4) ability to operate dissolution testers, UV–vis, and flame atomic absorption spectrophotometers; and (5) improved knowledge and understanding of figures of merit and statistical analysis