Pseudocapacitors harness unique charge-storage mechanisms to enable high-capacity, rapidly cycling devices. Here we describe an organic system composed of perylene diimide and hexaazatrinaphthylene ...exhibiting a specific capacitance of 689 F g
at a rate of 0.5 A g
, stability over 50,000 cycles, and unprecedented performance at rates as high as 75 A g
. We incorporate the material into two-electrode devices for a practical demonstration of its potential in next-generation energy-storage systems. We identify the source of this exceptionally high rate charge storage as surface-mediated pseudocapacitance, through a combination of spectroscopic, computational and electrochemical measurements. By underscoring the importance of molecular contortion and complementary electronic attributes in the selection of molecular components, these results provide a general strategy for the creation of organic high-performance energy-storage materials.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
Pseudocapacitors offer a unique strategy to combine the rapid charging rates of capacitors with the high energy density of batteries, potentially offering a unique solution to energy storage ...challenges. Bending and twisting aromatic building blocks to form contorted aromatics have emerged as a new strategy to create organic materials with unique and tunable properties. This paper studies the union between these two concepts: molecular contortion and organic pseudocapacitors. The recent development of fully organic pseudocapacitors, including high-performing devices based on perylene diimide organic redox units, introduces the added benefit of low cost, synthetic tunability, and increased flexibility. We synthesize a series of polymers by joining perylene diimide with various linkers that incorporate a helical moiety from 4helicene to 6helicene into the molecular backbone. We prepare three new electroactive polymers that incorporate benzene, naphthalene, and anthracene linkers and study their pseudocapacitive performance to infer key design principles for organic pseudocapacitors. Our results show that the naphthalene linker results in the most strongly coupled redox centers and displays the highest pseudocapacitance of 292 ± 47 F/g at 0.5 A/g. To understand the pseudocapacitive behavior, we synthesized dimer model compounds to further probe the electronic structure of these materials through electronic absorption spectroscopy and first-principles calculations. Our results suggest that the identity of the aromatic linker influences the contortion between neighboring perylene diimide units, the coupling between redox centers, and their relative angles and distances. We find that competing molecular design factors must be carefully optimized to generate high-performance devices. Overall, this study provides key insights into molecular design strategies for generating high-performing organic pseudocapacitor materials.
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IJS, KILJ, NUK, PNG, UL, UM
Many crystalline solids possess strongly anharmonic “soft” phonon modes characterized by diminishing frequency as temperature approaches a critical point associated with a symmetry breaking phase ...transition. While electron–soft phonon coupling can introduce unique scattering channels for charge carriers in ferroelectrics, recent studies on the nonferroelectric lead halide perovskites have also suggested the central role of anharmonic phonons bearing resemblance to soft modes in charge carrier screening. Here we apply coherent phonon spectroscopy to directly study electron coupling to the soft transverse optical phonon mode in a ferroelectric semiconductor SbSI. Photogenerated charge carriers in SbSI are found to be exceptionally long lived and are associated with a transient electro-optical effect that can be explained by interactions between charge carriers and thermally stimulated soft phonon excitations. Furthermore, these results provide strong evidence for the role of electron–soft phonon coupling in the efficient screening of charge carriers and in reducing charge recombination rates, both desirable properties for optoelectronics.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Chimeric antigen receptor-T (CAR-T) cell therapies can eliminate relapsed and refractory tumors, but the durability of antitumor activity requires in vivo persistence. Differential signaling through ...the CAR costimulatory domain can alter the T cell metabolism, memory differentiation, and influence long-term persistence. CAR-T cells costimulated with 4-1BB or ICOS persist in xenograft models but those constructed with CD28 exhibit rapid clearance. Here, we show that a single amino acid residue in CD28 drove T cell exhaustion and hindered the persistence of CD28-based CAR-T cells and changing this asparagine to phenylalanine (CD28-YMFM) promoted durable antitumor control. In addition, CD28-YMFM CAR-T cells exhibited reduced T cell differentiation and exhaustion as well as increased skewing toward Th17 cells. Reciprocal modification of ICOS-containing CAR-T cells abolished in vivo persistence and antitumor activity. This finding suggests modifications to the costimulatory domains of CAR-T cells can enable longer persistence and thereby improve antitumor response.
Many crystalline solids possess strongly anharmonic soft phonon modes characterized by diminishing frequency as temperature approaches a critical point associated with a symmetry breaking phase ...transition. While electron-soft phonon coupling can introduce unique scattering channels for charge carriers in ferroelectrics, recent studies on the non-ferroelectric lead halide perovskites have also suggested the central role of anharmonic phonons bearing resemblance to soft modes in charge carrier screening. Here we apply coherent phonon spectroscopy to directly study electron coupling to the soft transverse optical (TO) phonon mode in a ferroelectric semiconductor SbSI. Photo-generated charge carriers in SbSI are found to be exceptionally long lived and are associated with a transient electro-optical effect that can be explained by interactions between charge carriers and thermally stimulated soft-phonon excitations. These results provide strong evidence for the role of electron-soft phonon coupling in the efficient screening of charge carriers and in reducing charge recombination rates, both desirable properties for optoelectronics.
Successful tumor eradication by chimeric antigen receptor-expressing (CAR-expressing) T lymphocytes depends on CAR T cell persistence and effector function. We hypothesized that CD4+ and CD8+ T cells ...may exhibit distinct persistence and effector phenotypes, depending on the identity of specific intracellular signaling domains (ICDs) used to generate the CAR. First, we demonstrate that the ICOS ICD dramatically enhanced the in vivo persistence of CAR-expressing CD4+ T cells that, in turn, increased the persistence of CD8+ T cells expressing either CD28- or 4-1BB-based CARs. These data indicate that persistence of CD8+ T cells was highly dependent on a helper effect provided by the ICD used to redirect CD4+ T cells. Second, we discovered that combining ICOS and 4-1BB ICDs in a third-generation CAR displayed superior antitumor effects and increased persistence in vivo. Interestingly, we found that the membrane-proximal ICD displayed a dominant effect over the distal domain in third-generation CARs. The optimal antitumor and persistence benefits observed in third-generation ICOSBBz CAR T cells required the ICOS ICD to be positioned proximal to the cell membrane and linked to the ICOS transmembrane domain. Thus, CARs with ICOS and 4-1BB ICD demonstrate increased efficacy in solid tumor models over our current 4-1BB-based CAR and are promising therapeutics for clinical testing.
Excited state proton transfer (ESPT) is a unique photochemical process where the electron density shift of a molecule in the excited state dramatically decreases the pKa value of a proton donor site. ...A majority of ESPT research to date has focused on achiral molecules but there is growing interest in understanding/harnessing ESPT to/from chiral molecules. This review summarizes and critically examines the literature to date describing the role of ESPT in enantioselective fluorescence sensing, asymmetric synthetic organic chemistry, and photoisomerization of chiral molecules. Our goal is to show that despite ESPT of chiral molecules being a relatively new pursuit, there has been significant progress and even greater potential for ESPT in these and other applications yet to be realized.
Excitement about proton transfer! In the excited state, many chiral molecules can undergo excited state proton transfer (ESPT) which enables access to unique intermediates and reactivities. In this Review, we provide a comprehensive look at the literature describing ESPT to/from chiral molecules and their application in enantioselective fluorescence sensing, asymmetric synthetic organic chemistry, and photoisomerization
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Self-assembly of sensitizer and acceptor molecules has recently emerged as a promising strategy to facilitate and harness photon upconversion via triplet-triplet annihilation (TTA-UC). In addition to ...the energetic requirements, the structure and relative orientation of these molecules can have a strong influence on TTA-UC rates and efficiency. Here we report the synthesis of five different acceptor molecules composed of an anthracene core functionalized with 9,10- or 2,6-phenyl, methyl, or directly bound phosphonic acid groups and their incorporation into self-assembled bilayers on a ZrO2 surface. All five films facilitate green-to-blue photon upconversion with Φuc as high as 0.0023. The efficiency of TTA, and not triplet energy transfer, fluorescence, or losses via FRET, was primarily responsible for dictating the Φuc emission. Even for molecules having similar photophysical properties, variation in the position of the phosphonic acid resulted in dramatically different ΦTTA, Ith values, γTTA, and D. Interestingly, we observed a strong linear correlation between ΦTTA and the Ith value but the cause of this relationship, if any, is unclear.
Here we report a method for enantioenriching BINOL using a chiral auxiliary and an excited state proton transfer (ESPT) event. Regardless of the starting enantiomeric excess (ee), after irradiation ...the solution reaches a photostationary state whose ee is dependent solely on the identity of the chiral auxiliary group. The enantioenriched BINOL is easily recovered by cleaving the auxiliary group in mild conditions.
We describe a novel neurobehavioral phenotype of autism spectrum disorder (ASD), intellectual disability, and/or attention-deficit/hyperactivity disorder (ADHD) associated with de novo or inherited ...deleterious variants in members of the RFX family of genes. RFX genes are evolutionarily conserved transcription factors that act as master regulators of central nervous system development and ciliogenesis.
We assembled a cohort of 38 individuals (from 33 unrelated families) with de novo variants in RFX3, RFX4, and RFX7. We describe their common clinical phenotypes and present bioinformatic analyses of expression patterns and downstream targets of these genes as they relate to other neurodevelopmental risk genes.
These individuals share neurobehavioral features including ASD, intellectual disability, and/or ADHD; other frequent features include hypersensitivity to sensory stimuli and sleep problems. RFX3, RFX4, and RFX7 are strongly expressed in developing and adult human brain, and X-box binding motifs as well as RFX ChIP-seq peaks are enriched in the cis-regulatory regions of known ASD risk genes.
These results establish a likely role of deleterious variation in RFX3, RFX4, and RFX7 in cases of monogenic intellectual disability, ADHD and ASD, and position these genes as potentially critical transcriptional regulators of neurobiological pathways associated with neurodevelopmental disease pathogenesis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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