Isolation, characterization and whole-genome analysis of G9 group a rotaviruses in China: Evidence for possible Porcine-Human interspecies transmission.

Group A rotaviruses (RVAs) are major causes of severe gastroenteritis in infants and young animals. To enhance our understanding of the relationship between human and animals RVAs, complete genome data are necessary. We screened 92 intestinal and stool samples from diarrheic piglets by RT‒PCR targeting the VP6 gene, revealing a prevalence of 10.9%. RVA was confirmed in two out of 5 calf samples. We successfully isolated two porcine samples using MA104 cell line. The full-length genetic constellation of the two isolates were determined to be G9-P[23]-I5-R1-C1-M1-A8-N1-T7-E1-H1, with close similarity to human Wa-like and porcine strains. Sequence analysis revealed the majority of genes were closely related to porcine and human RVAs. Phylogenetic analysis revealed that these isolates might have their ancestral origin from pigs, although some of their gene segments were related to human strains. This study reveals evidence of reassortment and possible interspecies transmission between pigs and humans in China.

Development and Implementation of a Quadruple RT-qPCR Method for the Identification of Porcine Reproductive and Respiratory Syndrome Virus Strains.

BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) causes porcine reproductive and respiratory syndrome (PRRS), leading to abortion in sows and respiratory distress in breeding pigs. In China, PRRSV1 and PRRSV2 are the two circulating genotypes in swine herds, with distinct virulence. PRRSV2 further consists of classical (C-PRRSV2), highly pathogenic (HP-PRRSV2), and NADC30-Like (N-PRRSV2) subtypes. The diversity of PRRSV poses challenges for control and eradication, necessitating reliable detection assays for differentiating PRRSV genotypes. METHODS: A new TaqMan-based RT-qPCR assay with four sets of primers and probes targeting conserved regions of the ORF7 and NSP2 genes of PRRSV was developed, optimized, and evaluated by us. Reaction conditions such as annealing temperature, primer concentration, and probe concentration were optimized for the assay. Specificity, sensitivity, repeatability, stability, limit of detection (LOD), concordance with the reference method were evaluated for the assay. RESULTS: The assay could detect and type PRRSV1, C-PRRSV2, HP-PRRSV2, and N-PRRSV2 simultaneously with 97.33% specificity, 96.00% sensitivity, 12 copies/µL LOD, 97.00% concordance with reference assays. We applied the assay to 321 clinical samples from swine farms in China. The assay successfully detected and typed 230 PRRSV-positive samples, with 24.78% (57/230) of them further confirmed by ORF5 gene sequencing. The prevalence of PRRSV subtypes among the positive samples was as follows: C-PRRSV2 (15.22%), HP-PRRSV2 (23.48%), and N-PRRSV2 (61.30%). Two samples showed coinfection with different PRRSV subtypes. CONCLUSION: The quadruple RT-qPCR assay is a powerful tool for detecting and typing the currently circulating PRRSV strains in Chinese swine populations. It can assist in the surveillance of PRRSV prevalence and the implementation of prevention and control strategies.

Nano Si-Doped Ruthenium Oxide Particles from Caged Precursors for High-Performance Acidic Oxygen Evolution.

RuO2 is well known as the benchmark acidic oxygen evolution reaction (OER) catalyst, but its practical application has been impeded by its limited durability. Herein, it is presented that the stability of ruthenium oxide can be significantly improved by pretrapping RuCl3 precursors within a cage compound possessing 72 aromatic rings, which leads to well carbon-coated RuOx particles (Si-RuOx @C) after calcination. The catalyst survives in 0.5 M H2 SO4 for an unprecedented period of 100 hours at 10 mA cm-2 with minimal overpotential change during OER. In contrast, RuOx prepared from similar non-tied compounds doesn't exhibit such catalytic activity, highlighting the importance of the preorganization of Ru precursors within the cage prior to calcination. In addition, the overpotential at 10 mA cm-2 in acid solution is only 220 mV, much less than that of commercial RuO2 . X-ray absorption fine structure (FT-EXAFS) reveals the Si doping through unusual Ru-Si bond, and density functional theory (DFT) calculation reveals the importance of the Ru-Si bond in enhancing both the activity and stability of the catalyst.

Comparison of Preprint Postings of Randomized Clinical Trials on COVID-19 and Corresponding Published Journal Articles: A Systematic Review.

Importance: Randomized clinical trials (RCTs) on COVID-19 are increasingly being posted as preprints before publication in a scientific, peer-reviewed journal. Objective: To assess time to journal publication for COVID-19 RCT preprints and to compare differences between pairs of preprints and corresponding journal articles. Evidence Review: This systematic review used a meta-epidemiologic approach to conduct a literature search using the World Health Organization COVID-19 database and Embase to identify preprints published between January 1 and December 31, 2021. This review included RCTs with human participants and research questions regarding the treatment or prevention of COVID-19. For each preprint, a literature search was done to locate the corresponding journal article. Two independent reviewers read the full text, extracted data, and assessed risk of bias using the Cochrane Risk of Bias 2 tool. Time to publication was analyzed using a Cox proportional hazards regression model. Differences between preprint and journal article pairs in terms of outcomes, analyses, results, or conclusions were described. Statistical analysis was performed on October 17, 2022. Findings: This study included 152 preprints. As of October 1, 2022, 119 of 152 preprints (78.3%) had been published in journals. The median time to publication was 186 days (range, 17-407 days). In a multivariable model, larger sample size and low risk of bias were associated with journal publication. With a sample size of less than 200 as the reference, sample sizes of 201 to 1000 and greater than 1000 had hazard ratios (HRs) of 1.23 (95% CI, 0.80-1.91) and 2.19 (95% CI, 1.36-3.53) for publication, respectively. With high risk of bias as the reference, medium-risk articles with some concerns for bias had an HR of 1.77 (95% CI, 1.02-3.09); those with a low risk of bias had an HR of 3.01 (95% CI, 1.71-5.30). Of the 119 published preprints, there were differences in terms of outcomes, analyses, results, or conclusions in 65 studies (54.6%). The main conclusion in the preprint contradicted the conclusion in the journal article for 2 studies (1.7%). Conclusions and Relevance: These findings suggest that there is a substantial time lag from preprint posting to journal publication. Preprints with smaller sample sizes and high risk of bias were less likely to be published. Finally, although differences in terms of outcomes, analyses, results, or conclusions were observed for preprint and journal article pairs in most studies, the main conclusion remained consistent for the majority of studies.

Cage-modified hypocrellin against multidrug-resistant Candida spp. with unprecedented activity in light-triggered combinational photodynamic therapy.

Infections caused by multidrug-resistant fungi pose a devastating threat to human health worldwide, making new antifungal strategies urgently desired. Antimicrobial photodynamic therapy (aPDT) has gained increasing attention due to its potential in fighting against fungal infection. However, the preparation of highly efficient and water-soluble photosensitizers (PSs) for this purpose remains a challenge. Herein, we present a new strategy to prepare powerful PSs for efficient aPDT by introducing a porous cage compound, which could facilitate the transportation of O2 and reactive oxygen species (ROS). Specifically, the natural PS hypocrellin A (HA) was attached to a novel organic cage compound (covalent organic polyhedra 1 tied, COP1T) with polyethylene glycol (PEG) chains to improve its water solubility. It was found that the resulting COP1T-HA exhibited in vitro antifungal efficiency several folds higher compared to the free HA in fighting against four types of multidrug-resistant fungal planktonic cells and biofilms, including the "super fungus" Candida auris. Interestingly, the red-shift of COP1T-HA adsorption led to the realization of phototheranostic aPDT for cage-modified HA or derivatives. Additionally, COP1T-HA exhibited good biocompatibility, excellent disinfection capacity and wound healing efficiency without obvious toxic effects in vivo of rat model. With further development and optimization, COP1T-HA has great potential to become a new class of antifungal agent to fight against drug-resistant pathogens.

Molecular evolution and genetic characteristics of G3P[3] group A canine rotavirus isolated in Wuhan, China.

Rotaviruses can infect multiple animal species and have the potential for cross-recombination based on the segmented genome characteristics. To study the intra-host recombination and zoonotic potential of group A canine rotavirus (CRV), 438 samples were collected from domestic dogs in six animal hospitals and from stray dogs from October 2019 to May 2021 in Wuhan, China. Seven of the samples were positive (7/438) for group A CRV from which a CRV strain was successfully isolated in MA-104 cells. The genotype of the isolated strain was characterized by whole-genome sequencing showing that the genotype was group A CRV G3P[3]. According to the Rotavirus Classification Working Group (RCWG), the genomic constellation of the isolated CRV was G3-P[3]-I3-R3-C3-M3-A9-N2-T3-E3-H6, which belongs to the AU-1-like group with gene segments of AU-1-like and Cat 97-like strains. Based on the phylogenetic analysis of the 11 gene segments, we found that the different segments of the isolated group A CRV were closely related to several reassortment rotaviruses from different animal sources and bat strains. Based on the analysis of the molecular evolution and genetic characteristics, we concluded that the isolated strain might be a reassortment strain. These data further enrich our understanding of rotavirus molecular evolution and genetic characteristics in China.

Facile and General Method to Synthesize Pt-Based High-Entropy-Alloy Nanoparticles.

Pt-based high-entropy-alloy nanoparticles (HEA-NPs) have excellent physical and chemical properties due to the diversity of composition, complexity of surface structure, high mixing entropy, and properties of nanoscale, and they are used in a wide range of catalytic applications such as catalytic ammoxidation, the electrolysis of water to produce hydrogen, CO2/CO reduction, and ethanol/methanol oxidation reaction. However, offering a facile, low-cost, and large-scale method for preparing Pt-based HEA-NPs still faces great challenges. In this study, we employed a spray drying technique combined with thermal decomposition reduction (SD-TDR) method to synthesize a single-phase solid solution from binary nanoparticles to denary Pt-based HEA-NPs containing 10 dissimilar elements loaded on carbon supports in an H2 atmosphere with a moderate heating rate (3 °C/min), thermal decomposition temperature (300-850 °C), duration time (30 min), and low cooling rate (5-10 °C/min). The Pt autocatalytic behavior was found and investigated, confirming that Pt element could decrease the reduction temperature of other metals via autocatalytic behavior. Therefore, using the feature of Pt autocatalytic behavior, we have achieved Pt-based HEA-NPs at a minimum temperature of 300 °C. We not only prepared a series of Pt-based HEA-NPs with targetable ingredient, size, and phase using the SD-TDR method but also proved the expandability of the SD-TDR technique by synthesizing Pt-based HEA-NPs loaded on different supports. Moreover, we investigated methanol oxidation reaction (MOR) on as-synthesized senary PtCoCuRuFeNi HEA-NPs, which presented superior electrocatalytic performance over commercial Pt/C catalyst.

Achieving Balanced Electrical Performance of Host Material through Dual N-P═O Resonance Linkage for Efficient Electroluminescence.

Developing high-performance host materials is one of the biggest challenges for blue and white thermally activated delayed-fluorescence (TADF) organic light-emitting diode (OLED) technology due to the rigorous requirements of both efficient carrier flux ability and high triplet energy (ET) levels in static donor-acceptor molecules. Here, with the aid of a dual-resonance strategy, a host molecule showing dynamic adaption features in the acceptor-resonance-donor-resonance-acceptor (A-r-D-r-A) molecular configuration has been successfully developed through the implantation of two acceptors of diphenylphosphine oxide into electron-donating 5,10-dihydrophenazine with N-P═O resonance linkages. Owing to the dual enantiotropic N+═P-O- resonances, the designed A-r-D-r-A molecule exhibits an extraordinarily balanced charge flux transportation attribute at high ET (2.96 eV). Excitingly, blue and warm-white TADF OLEDs hosted by the A-r-D-r-A molecule exhibit outstanding external quantum efficiencies of 14.7 and 20.3%, respectively. Our studies not only broaden the scope of resonance molecules but also indicate that a resonance structure is an effective linkage to develop optoelectronic materials with dynamically adaptive properties.

Asymmetric Thermally Activated Delayed Fluorescence Materials With Aggregation-Induced Emission for High-Efficiency Organic Light-Emitting Diodes.

The exploitation of thermally activated delayed fluorescence (TADF) emitters with aggregation-induced emission is highly prerequisite for the construction of highly efficient electroluminescent devices in materials science. Herein, two asymmetric TADF emitters of SFCOCz and SFCODPAC with charming aggregation-induced emission are expediently designed and prepared based on highly twisted strong electron-withdrawing acceptor (A) of sulfurafluorene (SF)-modified ketone (CO) and arylamine donor (D) in D1-A-D2 architecture by simple synthetic procedure in high yields. High photoluminescence quantum yields up to 73% and small singlet-triplet splitting of 0.03 eV; short exciton lifetimes are obtained in the resultant molecules. Strikingly, efficient non-doped and doped TADF organic light-emitting diodes (OLEDs) facilitated by these emitters show high luminance of 5,598 and 11,595 cd m-2, current efficiencies (CEs) of 16.8 and 35.6 cd/A, power efficiencies (PEs) of 9.1 and 29.8 lm/W, and external quantum efficiencies (EQEs) of 7.5 and 15.9%, respectively. This work furnishes a concrete instance in exploring efficient TADF emitter, which is highly conducive and encouraging in stimulating the development of TADF OLEDs with high brightness and excellent efficiencies simultaneously.

Stimuli-Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence.

Purely organic materials showing room temperature phosphorescence (RTP) and ultralong RTP (OURTP) have recently attracted much attention. However, it is challenging to integrate circularly polarized luminescence (CPL) into RTP/OURTP. Here, we show a strategy to realize CPL-active OURTP (CP-OURTP) by binding an achiral phosphor group directly to the chiral center of an ester chain. Engineering of this flexible chiral chain enables efficient chirality transfer to carbazole aggregates, resulting in strong CP-OURTP with a lifetime of over 0.6 s and dissymmetry factor of 2.3×10-3 after the conformation regulation upon photo-activation. The realized CP-OURTP is thus stable at room temperature but can be deactivated quickly at 50 °C to CP-RTP with high CPL stability during the photo-activation/thermal-deactivation cycles. Based on this extraordinary photo/thermal-responsive and highly reversible CP-OURTP/RTP, a CPL-featured lifetime-encrypted combinational logic device has been successfully established.

Synthesis of PtCoNiRu/C nanoparticles by spray drying combined with reduction sintering for methanol electro-oxidation.

The controllable synthesis of carbon-supported platinum-based multicomponent alloys is important for the development and application of direct methanol fuel cells (DMFCs). In this paper, controllable synthesis of carbon-supported PtCoNiRu quaternary alloy is realized by spray drying and reduction sintering. The effects of reduction temperature on the size, morphology and catalytic properties of the metal nanoparticles were investigated. The electrochemical performance of the as-synthesized PtCoNiRu/C catalysts towards methanol electro-oxidation was studied using cyclic voltammetry (CV) and chronoamperometry. The results show that metal nanoparticles with uniform size and dispersity on the carbon surface can be obtained at a suitable sintering temperature, while the catalyst has a higher electrochemical active surface area (ECSA) and shows better catalytic activity and stability for methanol electro-oxidation. The method described in this study provides a new route for the manufacture of Pt alloy nanoparticles with higher catalytic activity and stability.

Caloric restriction inhibits mammary tumorigenesis in MMTV-ErbB2 transgenic mice through the suppression of ER and ErbB2 pathways and inhibition of epithelial cell stemness in premalignant mammary tissues.

Caloric intake influences the onset of many diseases, including cancer. In particular, caloric restriction (CR) has been reported to suppress mammary tumorigenesis in various models. However, the underlying cancer preventive mechanisms have not been fully explored. To this end, we aimed to characterize the anticancer mechanisms of CR using MMTV-ErbB2 transgenic mice, a well-established spontaneous ErbB2-overexpressing mammary tumor model, by focusing on cellular and molecular changes in premalignant tissues. In MMTV-ErbB2 mice with 30% CR beginning at 8 weeks of age, mammary tumor development was dramatically inhibited, as exhibited by reduced tumor incidence and increased tumor latency. Morphogenic mammary gland analyses in 15- and 20-week-old mice indicated that CR significantly decreased mammary epithelial cell (MEC) density and proliferative index. To understand the underlying mechanisms, we analyzed the effects of CR on mammary stem/progenitor cells. Results from fluorescence-activated cell sorting analyses showed that CR modified mammary tissue hierarchy dynamics, as evidenced by decreased luminal cells (CD24highCD49flow), putative mammary reconstituting unit subpopulation (CD24highCD49fhigh) and luminal progenitor cells (CD61highCD49fhigh). Mammosphere and colony-forming cell assays demonstrated that CR significantly inhibited mammary stem cell self-renewal and progenitor cell numbers. Molecular analyses indicated that CR concurrently inhibited estrogen receptor (ER) and ErbB2 signaling. These molecular changes were accompanied by decreased mRNA levels of ER-targeted genes and epidermal growth factor receptor/ErbB2 family members and ligands, suggesting ER-ErbB2 signaling cross-talk. Collectively, our data demonstrate that CR significantly impacts ER and ErbB2 signaling, which induces profound changes in MEC reprogramming, and mammary stem/progenitor cell inhibition is a critical mechanism of CR-mediated breast cancer prevention.

DMBA promotes ErbB2­mediated carcinogenesis via ErbB2 and estrogen receptor pathway activation and genomic instability.

Environmental factors, including 7,12­dimethylbenz[a]anthracene (DMBA) exposure, and genetic predisposition, including ErbB2 overexpression/amplification, have been demonstrated to increase breast cancer susceptibility. Although DMBA­ and ErbB2­mediated breast cancers are well­studied in their respective models, key interactions between environmental and genetic factors on breast cancer risk remain unclear. Therefore, the present study aimed to investigate the effect of DMBA exposure on ErbB2­mediated mammary tumorigenesis. MMTV­ErbB2 transgenic mice exposed to DMBA (1 mg) via weekly oral gavage for 6 weeks exhibited significantly enhanced mammary tumor development, as indicated by reduced tumor latency and increased tumor multiplicity compared with control mice. Whole mount analysis of premalignant mammary tissues from 15­week­old mice revealed increased ductal elongation and proliferative index in DMBA­exposed mice. Molecular analyses of premalignant mammary tissues further indicated that DMBA exposure enhanced epidermal growth factor receptor (EGFR)/ErbB2 and estrogen receptor (ER) signaling, which was associated with increased mRNA levels of EGFR/ErbB2 family members and ER­targeted genes. Furthermore, analysis of tumor karyotypes revealed that DMBA­exposed tumors displayed more chromosomal alterations compared with control tumors, implicating DMBA­induced chromosomal instability in tumor promotion in this model. Together, the data suggested that DMBA­induced deregulation of EGFR/ErbB2­ER pathways plays a critical role in the enhanced chromosomal instability and promotion of ErbB2­mediated mammary tumorigenesis. The study highlighted gene­environment interactions that may increase risk of breast cancer, which is a critical clinical issue.

Identification and functional analysis of the novel ORF6 protein of porcine circovirus type 2 in vitro.

In the present study, the function of a novel ORF6 gene in the PCV2 genome was determined and functionally analyzed in vitro. ORF6 expression was demonstrated by indirect immunofluorescence in PCV2-infected cells. The antibody against ORF6 was detected in PCV2-infected pigs. The start codon of ORF6 was mutated and an infectious clone was used to create an ORF6-deficient mutant virus. Viral DNA replication curves and immunofluorescence analysis indicated that ORF6 is unnecessary for viral replication and ORF6 deletion reduces viral DNA replication in PK-15 cells. The activities of caspases 3 and 8 in ORF6-deficient virus-infected cells were significantly different from those in wild-type virus-infected cells. The ORF6 protein can increase the expression of IFN-ß, TNF-α, IL-1b, IL-10, and IL-12p40. These results demonstrated that the newly discovered ORF6 protein may be involved in caspases regulation and the expression of multiple cytokines in PCV2-infected cells. The functions of this gene in viral pathogenesis remain to be further elucidated.

Molecular cloning and functional characterization of duck nucleotide-binding oligomerization domain 1 (NOD1).

Nucleotide-binding oligomerization domain 1 (NOD1) is an imperative cytoplasmic pattern recognition receptor (PRR) and considered as a key member of the NOD-like receptor (NLR) family which plays a critical role in innate immunity through sensing microbial components derived from bacterial peptidoglycan. In the current study, the full-length of duck NOD1 (duNOD1) cDNA from duck embryo fibroblasts (DEFs) was cloned. Multiple sequence alignment and phylogenetic analysis demonstrated that duNOD1 exhibited a strong evolutionary relationship with chicken and rock pigeon NOD1. Tissue-specific expression analysis showed that duNOD1 was widely distributed in various organs, with the highest expression observed in the liver. Furthermore, duNOD1 overexpression induced NF-κB activation in DEFs and the CARD domain is crucial for duNOD1-mediated NF-κB activation. In addition, silencing the duNOD1 decreased the activity of NF-κB in DEFs stimulated by iE-DAP. Overexpression of duNOD1 significantly increased the expression of TNF-α, IL-6, and RANTES in DEFs. These findings highlight the crucial role of duNOD1 as an intracellular sensor in duck innate immune system.

Porcine reproductive and respiratory syndrome virus 3C protease cleaves the mitochondrial antiviral signalling complex to antagonize IFN-ß expression.

Porcine reproductive and respiratory syndrome, a highly infectious disease caused by porcine reproductive and respiratory syndrome virus (PRRSV), has developed various strategies to evade the host innate immune response, including the suppression of type I IFN activation. The mitochondrial antiviral signalling protein (MAVS) is an important bridging adaptor of retinoic acid-inducible gene I/melanoma differentiation-associated protein 5 signalling pathways. Here, we demonstrated that the 3C-like protease (3CLSP) of PRRSV prevented the induction of IFN-ß by cleaving MAVS in a proteasome- and caspase-independent manner. Moreover, this cleavage ability was dependent on the protease activity of 3CLSP. Mutations specifically disrupting the cysteine protease activity of 3CLSP eliminated MAVS cleavage and the inhibition of IFN induction. Subsequently, we determined that 3CLSP cleaved MAVS at Glu268. Remarkably, a MAVS point mutation at Glu268 rendered MAVS resistant to 3CLSP cleavage. These results reveal a novel PRRSV mechanism to escape host immunity by directly cleaving MAVS.

Combination therapy with TNFR-Fc and CTLA4-FasL using the recombinant adeno-associated virus potently suppresses adjuvant-induced arthritis in rats.

The complexity of rheumatoid arthritis (RA) pathogenesis makes combined blockade of key pathogenic factors an attractive therapeutic strategy. We have previously reported a novel recombinant adeno-associated virus (AAV) vector, AAV.TFCF, which mediates separate coexpression of TNFα antagonist TNFR-Fc and T cell antagonist CTLA4-FasL both in vitro and in vivo (the injected joints). The purpose of this study was to examine the efficacy of TNFR-Fc/CTLA4-FasL combination therapy mediated by AAV.TFCF in experimental model of RA. Adjuvant-induced arthritis (AIA) was induced in Lewis rats, and the recombinant AAV.TFCF was injected into rat ankle joints. AAV vector encoding CTLA4-FasL (AAV.CTFA) or TNFR-Fc (AAV.TRFC) was used as the monotherapy control, and an AAV vector mediating the expression of enhanced green fluorescent protein (AAV.EGFP) was used as the negative control. The combination treatment mediated by AAV.TFCF demonstrated a more effective suppression of AIA compared with those monotherapy controls, as reflected in the clinical and histological observations. The synergistic anti-inflammatory effect of TNFR-Fc combining with CTLA4-FasL was proved to be associated with the greater reductions of inflammatory CD4+ T cell infiltration and proinflammatory cytokine TNFα level in the arthritic joints. In addition, the combination therapy was found to be able to increase the frequency of CD4 + CD25 + FoxP3+ regulatory T cell population in rat draining lymph nodes and suppress splenic inflammatory responses. These results suggest that combination treatment with TNFR-Fc and CTLA4-FasL may achieve superior efficacy in suppressing RA, and using this novel recombinant AAV.TFCF to obtain the combined counteraction of both pathogenic T cells and the key proinflammatory cytokine TNFα may provide a more effective and desirable strategy for treatment of RA.

Light-induced N2O production from a non-heme iron-nitrosyl dimer.

Two non-heme iron-nitrosyl species, [Fe2(N-Et-HPTB)(O2CPh)(NO)2](BF4)2 (1a) and [Fe2(N-Et-HPTB)(DMF)2(NO)(OH)](BF4)3 (2a), are characterized by FTIR and resonance Raman spectroscopy. Binding of NO is reversible in both complexes, which are prone to NO photolysis under visible light illumination. Photoproduction of N2O occurs in high yield for 1a but not 2a. Low-temperature FTIR photolysis experiments with 1a in acetonitrile do not reveal any intermediate species, but in THF at room temperature, a new {FeNO}(7) species quickly forms under illumination and exhibits a ν(NO) vibration indicative of nitroxyl-like character. This metastable species reacts further under illumination to produce N2O. A reaction mechanism is proposed, and implications for NO reduction in flavodiiron proteins are discussed.

Thioether-ligated iron(II) and iron(III)-hydroperoxo/alkylperoxo complexes with an H-bond donor in the second coordination sphere.

The non-heme iron complexes, [Fe(II)(N3PySR)(CH3CN)](BF4)2 () and [Fe(II)(N3Py(amide)SR)](BF4)2 (), afford rare examples of metastable Fe(iii)-OOH and Fe(iii)-OOtBu complexes containing equatorial thioether ligands and a single H-bond donor in the second coordination sphere. These peroxo complexes were characterized by a range of spectroscopic methods and density functional theory studies. The influence of a thioether ligand and of one H-bond donor on the stability and spectroscopic properties of these complexes was investigated.

Versatile reactivity of a solvent-coordinated diiron(II) compound: synthesis and dioxygen reactivity of a mixed-valent Fe(II)Fe(III) species.

A new, DMF-coordinated, preorganized diiron compound [Fe2(N-Et-HPTB)(DMF)4](BF4)3 (1) was synthesized, avoiding the formation of [Fe(N-Et-HPTB)](BF4)2 (10) and [Fe2(N-Et-HPTB)(µ-MeCONH)](BF4)2 (11), where N-Et-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane. Compound 1 is a versatile reactant from which nine new compounds have been generated. Transformations include solvent exchange to yield [Fe2(N-Et-HPTB)(MeCN)4](BF4)3 (2), substitution to afford [Fe2(N-Et-HPTB)(µ-RCOO)](BF4)2 (3, R = Ph; 4, RCOO = 4-methyl-2,6-diphenyl benzoate]), one-electron oxidation by (Cp2Fe)(BF4) to yield a Robin-Day class II mixed-valent diiron(II,III) compound, [Fe2(N-Et-HPTB)(µ-PhCOO)(DMF)2](BF4)3 (5), two-electron oxidation with tris(4-bromophenyl)aminium hexachloroantimonate to generate [Fe2(N-Et-HPTB)Cl3(DMF)](BF4)2 (6), reaction with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl to form [Fe5(N-Et-HPTB)2(µ-OH)4(µ-O)(DMF)2](BF4)4 (7), and reaction with dioxygen to yield an unstable peroxo compound that decomposes at room temperature to generate [Fe4(N-Et-HPTB)2(µ-O)3(H2O)2](BF4)·8DMF (8) and [Fe4(N-Et-HPTB)2(µ-O)4](BF4)2 (9). Compound 5 loses its bridging benzoate ligand upon further oxidation to form [Fe2(N-Et-HPTB)(OH)2(DMF)2](BF4)3 (12). Reaction of the diiron(II,III) compound 5 with dioxygen was studied in detail by spectroscopic methods. All compounds (1-12) were characterized by single-crystal X-ray structure determinations. Selected compounds and reaction intermediates were further examined by a combination of elemental analysis, electronic absorption spectroscopy, Mössbauer spectroscopy, EPR spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry.