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ABSTRACT The pursuit of sustainable organic synthesis has renewed interest in photochemistry, as sunlight‐driven reactions provide eco‐friendly alternative methods. Although the relationships among structure, properties, and reactivity are well established for ground‐state molecules, the understanding of excited states and reactive intermediates, such as triplet and singlet arylnitrenes, remains limited. Herein, we investigated the properties of triplet and singlet 4‐nitrenopyridine‐1‐pyridine oxide (1N), 3‐nitrenopyridine‐1‐pyridine oxide (2N), and phenylnitrene (PhN) using density functional theory (DFT), complete active space self‐consistent field (CASSCF(10,9)), and complete active space second‐order perturbation theory (CASPT2(10,9)) calculations. Bond length analysis demonstrated that³1Nand¹1N, as well as¹2Nand¹PhN, exhibit significant imine biradical character, whereas the structures of³2Nand³PhNare better described as benzene‐like. Nucleus‐independent chemical shift (NICS(0), NICS(1.7)_ZZ) and anisotropy of induced current density (ACID) calculations were performed to compare the induced magnetic currents in these molecules. These analyses demonstrated that³1Nis weakly aromatic, whereas³2Nand³PhNare best described as having Baird aromaticity. In contrast, singlet nitrenes¹1N,¹2N, and¹PhNare nonaromatic. In addition, irradiation of1in argon matrices verified that³1Nreacts photochemically to form corresponding ketenimine1K. Finally, the absorption difference spectrum of³1Nin a frozen 2‐methyltetrahydrofuran (mTHF) matrix exhibited resolved vibrational structure, suggesting the vibrational coupling to another electronic state. These insights into the structure and aromaticity of heterocyclic nitrenes could provide new avenues for modulating the reactivity of triplet ground state and triplet excited molecules. 

Despite their versatile synthetic utility, vinyl azides have complex and poorly understood photochemistry. To address this, we investigated the photoreactivity of 1-azidostyrene 1 and 3-phenyl-2H-azirine 2 in solution and cryogenic matrices. In argon matrices, irradiation of 1 at 254 nm yielded 2, phenyl nitrile ylide 3, and N-phenyl ketenimine 4, whereas irradiation at wavelengths above 300 nm produced only 2 and 4. Similarly, irradiation of 1 in 2-methyltetrahydrofuran (mTHF) glass at 77 K mainly yielded absorption corresponding to the formation of 2 (λmax ~ 252 nm). In contrast, irradiation of 2 at wavelengths above 300 nm in Argon matrices yielded no photoproducts, whereas irradiation at 254 nm resulted in the formation of 3. Furthermore, femto- and nanosecond transient absorption and laser flash photolysis were performed to ascertain the transient species and reactive intermediates formed during the photochemical transformations of 1 and 2. The ultrafast transient absorption spectroscopy of 1 resulted in a transient absorption band centered at ca. 472 nm with a time constant τ ~ 22 ps, which was assigned to the first singlet excited state (S1) of 1. The nano-second flash photolysis of 1 (308 nm laser) generated 2 within the laser pulse (~17 ns), and subsequently 2 is excited to yield triplet vinylnitrene 31N with an absorption centered at ~ 440 nm. In contrast, the nano-second laser flash photolysis of 2 with 266 nm laser produced a weak absorption corresponding to 3, whereas 308 nm laser yielded absorption due to triplet vinylnitrene 31N (λmax ~ 440 nm). These findings demonstrate that the direct irradiation of 1 populates S1 of 1, which does not intersystem cross to form 31N, but instead decays to yield 2. Density functional theory calculations supported the characteristics of the excited states and reactive intermediates formed upon irradiation of 1 and 2. 

Abstract Over the interval 2008–2023 a large number of studies have been published testing various aspects of punctuated equilibria, including the prevalence of stasis, and also the extent to which most evolutionary change is concentrated at cladogenesis. In the vast majority of studies, punctuated equilibria continued to be strongly validated, as widespread evidence for stasis accumulated, with only some rare incidences of gradual change found. Support for the importance of cladogenetic change has increased, and new analytical approaches to study punctuated equilibria have been developed. Over this time period, there has also been an increase in the number of studies that have concentrated on extant taxa to test for punctuated equilibria, and these have also corroborated its widespread presence. In this respect, punctuated equilibria has served as an important bridge between neontological and paleontological approaches to evolutionary biology. From 2008 to 2023, there has also been some drift in how stasis is defined, such that, in certain studies, the definition diverged from the original 1972 definition in important respects. Notably, it is the few studies that have most changed the definition of what stasis constitutes that have most challenged the validity of punctuated equilibria, indicating it is morphing interpretations and definitions rather than the discovery of data compatible with phyletic gradualism that are most responsible for divergent results. 

Abstract Most species exhibit morphological stasis following speciation, and this is a key feature of the concept of punctuated equilibria. Stasis results in species often having long durations on geological timescales. Durational data are fundamental to many types of paleobiological analyses and are ideally based on occurrence data represented by specimens in museum collections. Often, however, durational data are presented without supporting information about voucher specimens that document stratigraphic ranges, including first and last appearances. We use the iconic Devonian trilobiteEldredgeops ranato demonstrate that durational data can be challenging to determine at multiple taxonomic levels. Further, we show that different datasets—including Sepkoski’s published databases, the Paleobiology Database, and iDigBio—give discordant results concerning first and last occurrences. We argue that paleontologists should adopt two general best practices to help address these problems. First, systematists should clearly identify voucher specimens that represent stratigraphic occurrences of species. Second, we recommend that high-quality photographs of occurrence vouchers be placed in open access websites and be assigned public domain licensing before being paywalled by journals. Such voucher images also have a role to play in training artificial intelligence (AI) systems that will be applied to future paleobiological questions. 

Abstract Semiconducting polymers are of interest due to their solution processibility and broad electronic applications. Electrochemistry allows these wide bandgap semiconductors to be converted to conducting polymers by doping such polymers at various potentials. When polymers arep‐doped to improve their conductivity via electrochemical oxidation, various positively‐charged carriers are created, including polarons (singly‐charged) and bipolarons (doubly‐charged). Carrier creation is accompanied by anion intercalation from the electrolyte for charge balance, and this insertion requires ion mobility. In this work, poly(3‐hexylthiophene) (P3HT) with different regioregularities is used to understand the relationship between solvent swelling, which affects anion intercalation, and electrochemical doping. Cyclic voltammetry, optical absorption spectroscopy, and grazing incidence wide‐angle X‐ray scattering (GIWAXS) measurements are used to correlate the doping level with structural changes. In situ electrochemical quartz crystal microbalance (EQCM) measurements are used to quantify the swelling of the polymers dynamically during electrochemical cycling. Lastly, in situ conductivity measurements are done to measure the effect of swelling on the ionic and electronic conductivity. The results indicate that solvent swelling is required for bipolaron formation, and that swelling facilitates both the small structural changes need for polaron formation and the disordering required for bipolaron formation. 

We hypothesize that bacteria isolated from free-ranging animals could potentially be useful for practical applications. To meet this objective a Gram-positive bacterium was isolated from the gastrointestinal (GI) tract of a Gray Wolf (Canis lupus) using Brucella broth with hemin and vitamin K (BBHK). By small ribosomal RNA (16S) gene sequencing the bacterium was initially identified as a novel Carnobacterium maltaromaticum strain. The bacterium could be propagated both anaerobically and aerobically and was both catalase/oxidase negative and negative by the starch hydrolysis as well as negative using lipase assays. The reference whole genome sequence (WGS) was obtained using both Illumina and Nanopore sequencing. The genome assembly was 3,512,202 bp in length, encoding core bacterial genes with a GC% content of 34.48. No lysogenic bacteriophage genes were detected, although the genome harbors genes for the expression of bacteriocin and other secondary metabolites with potential antimicrobial properties. Multilocus sequence typing (MLST), WGS phylogenetics, average nucleotide identity (ANI), and single nucleotide polymorphism (SNP) analyses of the isolate’s genome indicate this bacterium is a newly identified Carnobacterium maltaromaticum sequence type (ST). Members of the Carnobacteria have anti-listeria activities, highlighting their potential functional properties. Consequently, the isolate could be a potential probiotic for canids and this is the first report on an axenic C. maltaromaticum culture from the genus Canis. 

The Plio-Pleistocene turnover event in the western Atlantic following the closure of the Central American Seaway involved high rates of extinction for both gastropod and bivalve molluscs. This extinction was associated with declining nutrient conditions and has been presumed to be associated with a decrease in molluscan body size. Previous work which has been concordant with this expectation, however, has either focused on bivalves or not considered the effects of the recovery post extinction. In three phylogenetically diverse clades, we found that body-size evolution in gastropods across the turnover event is likely tied to ecology. One clade increased in size, one decreased, and another exhibited no substantial change. Individual species lineages exhibit a mixture of microevolutionary changes from the Pliocene to today. This study indicates that gastropod body-size evolution may be more complex than in bivalves, with ecology and other functional traits playing a significant role. Macroevolutionary processes, especially whether a clade re-radiated post extinction, were found to be important. Indeed, a low portion of extant diversity consists of survivors from clades that increased in size or have similar size distributions among their species relative to the Pliocene. 

Photoenols, formed through photoinduced intra-molecular H atom abstraction in o-alkyl-substituted arylketones,typically have limited utility as reactive intermediates owing to fastreversion to the starting material. Herein, we introduced an azidogroup on the o-alkyl substituent to render the photoreactionirreversible. Irradiation of 2-azidomethylbenzophenone (1) inmethanol yielded 2-(hydroxy(phenyl)methyl)benzonitrile (2). Laser flash photolysis of 1 revealed the formation of biradical 3Br1followed by intersystem crossing to photoenols Z-3 (τ ∼ 3.3 μs) and E-3 (τ > 45 μs), both of which reverted to 1. Alternatively, 3Br1could lose N2 to form 3Br2 (not detected), which decays to 2. In cryogenic argon matrices, irradiation of 1 yielded nitrene 31N and 2but no photoenols, likely because Z-3 regenerated 1. Both ESR spectroscopy and absorption analysis in methyltetrahydrofuran (80K) confirmed 31N formation. Upon prolonged irradiation, the absorbance of 31N decreased, whereas that of 3 remained unchangedand that of 2 increased. Thus, TK of 1 is proposed to form 3Br1 via H atom abstraction, with subsequent intersystem crossing to 3competing with the loss of N2 to generate 3Br2. DFT calculations revealed a small energy gap (∼2 kcal/mol) between the triplet andsinglet configurations of Br2, supporting a mechanism in which 3Br2 intersystem crosses to yield 2 

The emergence of white-nose syndrome (WNS) in North America has resulted in mass mortalities of hibernating bats and total extirpation of local populations. The need to mitigate this disease has stirred a significant body of research to understand its pathogenesis.Pseudogymnoascus destructans, the causative agent of WNS, is a psychrophilic (cold-loving) fungus that resides within the class Leotiomycetes, which contains mainly plant pathogens and is unrelated to other consequential pathogens of animals. In this review, we revisit the unique biology of hibernating bats andP.destructansand provide an updated analysis of the stages and mechanisms of WNS progression. The extreme life history of hibernating bats, the psychrophilic nature ofP.destructans, and its evolutionary distance from other well-characterized animal-infecting fungi translate into unique host–pathogen interactions, many of them yet to be discovered. 

Millions of hibernating bats across North America have died from white-nose syndrome (WNS), an emerging disease caused by a psychrophilic (cold-loving) fungus,Pseudogymnoascus destructans, that invades their skin. Mechanisms ofP. destructansinvasion of bat epidermis remain obscure. Guided by our in vivo observations, we modeled hibernation with a newly generated little brown bat (Myotis lucifugus) keratinocyte cell line. We uncovered the stealth intracellular lifestyle ofP. destructans, which inhibits apoptosis of keratinocytes and spreads through the cells by two epidermal growth factor receptor (EGFR)–dependent mechanisms: active penetration during torpor and induced endocytosis during arousal. Melanin of endocytosedP. destructansblocks endolysosomal maturation, facilitatingP. destructanssurvival and germination after return to torpor. Blockade of EGFR abortsP. destructansentry into keratinocytes.