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Item Divergent Electrically Conductive Pathways in Yttrium-Based 2- and 3-Dimensional Metal–Organic Frameworks(American Chemical Society, 2024-07) Welty, Connor; Gormley, Eoghan L.; Oppenheim, Julius J.; Dincă, Mircea; Hendon, Christopher H.; Stadie, Nicholas P.Despite most porous framework solids exhibiting insulating character, some are known to conduct electrical charge. The peak performing conductive metal–organic frameworks are composed of redox-active hexasubstituted triphenylene linkers, but the impact of redox activity on material conductivity remains enigmatic because of limited availability of direct structure–function relationships. Here, we report a hexagonal yttrium-based conductive porous scaffold, comprising hexahydroxytriphenylene connected by Y-chains (YHOTP). In comparison to its known porous cubic counterpart (Y6HOTP2), this material features a 1000-fold increase in peak conductivity in polycrystalline samples (∼10–1 S cm–1). Furthermore, through a comparison of their electronic structures, we rationalize the origin of this difference and highlight the role of charge carrier concentration in dictating bulk electrical conductivity. Together, this work provides a design principle for the development of next-generation conductive porous frameworks.Item Discovering unknown associations between prokaryotic receptors and their ligands(Proceedings of the National Academy of Sciences, 2023-11) Dlakić, MensurThe motility of microorganisms through the environment is driven by chemical gradients: They move towards nutrients and away from signals that indicate unfavorable conditions. This chemotaxis is mediated by transmembrane chemoreceptors that recognize one or many target molecules. In most cases, the encounter with a ligand is recorded by a periplasmic sensor domain, which in turn transmits a signal through the membrane to a cytoplasmic signaling domain (1). Under conditions of environmental stress, these signaling cascades may induce profound lifestyle changes from planktonic cells to a biofilm or from active to inactive cells (2). While it is relatively straightforward to annotate most prokaryotic chemoreceptors from the ever-increasing number of sequenced genomes and environmental samples, the identity of their binding partners is often not clear from protein sequence. As the specificity of downstream signaling events is determined by the sensor domain, it is critical to learn about novel pairings between ligands and their receptors. Using a range of computational and experimental approaches, Cerna-Vargas et al. show in PNAS that a subset of a wide-spread group of dCache_1 receptors evolved to recognize various types of biological amines.