Reaction Patterns Research Articles

Flavin-Mediated Reductive Deiodination: Conformational Events and Reactivity Pattern in the Active Site of Human Iodotyrosine Deiodinase.

Human iodotyrosine deiodinase (hIYD) catalyzes the reductive deiodination of iodotyrosine using a flavin mononucleotide cofactor to maintain the iodine concentration in the body. Mutations in the hIYD gene are linked to human hypothyroidism, emphasizing its role in thyroid function regulation. The present work employs microsecond-scale molecular dynamics simulations and quantum chemical calculations to elucidate the conformational dynamics and reactivity in the active site at various stages of hIYD enzymatic cycle. The flavin is found to employ a unique butterfly motion of its isoalloxazine ring accompanied by a novel active-and-resting state of its ribose 2'-OH group at different stages of the enzymatic cycle. The flavin dynamics are found to control substrate binding affinity, the active site lid closure, and NADPH recognition. The predicted hIYD model shows enhanced stabilization of NADPH due to additional interactions with the N-terminal and intermediate domains. The enzyme uses a group of basic residues (R100, R101, R104, K182, and R279) to stabilize flavin in different stages of catalysis, suggesting potential mutations to control enzyme activity. The reactivity descriptors and stereoelectronic analysis predict the N5 nitrogen of flavin as a proton source during the reductive deiodination, while the anisotropic charge distribution on the halogen atom has negligible structural and electronic effects. The present findings provide key insights into the molecular basis of hIYD activity and lay the groundwork for future research aimed at therapeutic interventions and industrial applications.

Coupling of unactivated alkyl electrophiles using frustrated ion pairs

Cross-electrophile coupling reactions have evolved into a major strategy for rapidly assembling important organic molecules1. Two readily accessible electrophiles are coupled to form new C–C bonds, providing a key advantage over traditional cross-coupling strategies that require the preformation of reactive organometallic species. Yet, the formation of C(sp3)–C(sp3) bonds that form the core of nearly all organic compounds remains highly challenging with current approaches, calling for the design of innovative new strategies. Here we report a distinct, transition-metal-free platform to form such bonds without the need for activating or stabilizing groups on the coupling partners. The reaction is enabled by an unusual single-electron transfer in a frustrated ion pair, and it can couple fragments containing functional groups that would be challenging in related transition-metal-catalysed processes. Moreover, we could further leverage this new mechanistic manifold in the design of other reactions, showing the broad potential of this type of reactivity. We anticipate that our results will provide a framework for further exploration of this reactivity pattern to tackle challenging problems in organic synthesis.

Field versus controlled environmental experiments to evaluate the heat stress response of barley (Hordeum vulgare L.)

The complexity of heat stress hinders both the exploration of the genetic basis of stress response and breeding of genotypes with increased stress tolerance. Our main goal was to analyze and compare the possibilities of evaluating heat stress responses of barley cultivars in field sowing and controlled environmental experiments. For this purpose, a four-year field-sown experiment was carried out at one location in a panel of 190 winter and facultative barleys. In parallel, a subset of 28 cultivars were included into controlled environmental tests, where their reactions were determined to single heat stress treatment applied at heading and to combined heat stresses applied at first node appearance and then at heading. Based on the grain-yield related parameters, seven distinct clusters of the cultivars could be established with specific reaction patterns across the years. There was one year with close to optimal weather conditions and one year, when heat stress occurred during flowering and grain setting, making it possible to evaluate the heat stress responses of the 190 barley genotypes. In the heat stress prone 2022 year, the general trends were a strong reduction in the reproductive tiller number and a slight reduction in the fertility. In several groups, these negative effects were compensated with significant increases in grain number per ears and with strong increases in the average grain weight. Under controlled conditions, heat stress significantly reduced most of the grain-yield related traits. Among the more tolerant genotypes, two basic response types could be distinguished. One group was able to better preserve the grain number and weight in the main ear under heat stress, while the other was more able to allocate resources into the side tillers during the recovery period. In the combined heat stress, the average trait values were similar to those in the single stress or even lower, and there was no general priming effect clearly detectable. In the case of the 28 genotypes, there were significant correlations between the stress-induced changes in grain-yield related traits measured under field and under controlled conditions, underlining the possibility of combining the information originating from the two different environments.

Homobimetallic Ruthenium(II) Complexes Catalysed Selective Transfer Hydrogenation of Aldehydes in Water.

Herein we report chemoselective transfer hydrogenation (TH) of aldehydes in aqueous medium using a series of homobimetallic Ru(II) catalysts. Two homobimetallic complexes (Ru1 and Ru3) and one monometallic complex (Ru2) have been employed in the catalytic reduction of aldehydes. Bimetallic complex [(p-cymene)2(RuCl)2L3] (Ru3) is obtained from the reaction of Schiff base ligand 2,2'-((1E,1'E)-((3,3',5,5'-tetraisopropyl-[1,1'-biphenyl]-4,4'diyl)bis(azaneylylidene))bis(methaneylylidene))bis(4-bromophenol) (H2L3) and characterized by various spectroscopic and analytical techniques. The use of formic acid/formate buffer as the hydride source and a catalyst loading of 0.01 mol% of Ru1 or Ru3 resulted in the conversion of various aldehydes to the corresponding alcohols in good to excellent yield. This method is very efficient for selective reduction of aldehydes in the presence of other reducible functional groups. A loading of 0.0001 mol% of Ru1 catalyst is sufficient to achieve a turnover frequency (TOF) of 5.5× 105 h-1. Furthermore, the catalyst can been recycled and reused for six consecutives cycles without sacrificing the efficiency. A comparison of results obtained between bimetallic and monometallic complexes offers valuable insights into the distinct reactivity patterns of the bimetallic complexes, presumably originating from a cooperative effect. We have explored the mechanistic pathway using DFT methods.

Divalent Lanthanide Hydride Complexes

AbstractMolecular hydride complexes have attracted recent attention, and divalent lanthanides as central atoms in particular are very interesting. They open up possibilities of combining hydride reactivity and lanthanide reactivity. To date, only Yb(II), Eu(II) and Sm(II) as well as a mixed‐valent Dy(II)/Dy(III) hydride complexes have been isolated and characterised but the known examples are still low in numbers. In this contribution the development of divalent lanthanide chemistry is summarised, and structural features, reactivity patterns in stoichiometric and catalytic reactions as well as spectroscopic details are outlined.

Stepwise conversion of a 10‐membered diketo open‐cage [60]fullerene to a 10‐membered keto‐lactone open‐cage [60]fullerene

The chemical reactivity of a 10‐membered diketo open‐cage fullerene C60(O)2(OOtBu)4 was investigated in an effort to reveal the unique reaction pattern of fullerene derivatives. Selective cleavage of peroxo O‐O bonds was observed under thermolysis in the presence of iodine to form epoxy groups around the orifice. Opening of the epoxy groups leads to vicinal diol moiety, oxidation of which resulted in a new 10‐membered keto‐lactone open‐cage fullerene derivative. Single crystal X‐ray diffraction analysis showed that the size of the rectangular orifice is around 2.96´4.66 Å.

Access to Alkenyl Cyclobutanols by Ni‐Catalyzed Regio‐ and Enantio‐Selective syn‐Hydrometalative 4‐exo‐trig Cyclization of Alkynones

AbstractEnantioselective synthesis of (spiro)cyclobutane derivatives poses significant challenges yet holds promising applications for both synthetic and medicinal chemistry. We report here a nickel‐catalyzed asymmetric syn‐hydrometalative 4‐exo‐trig cyclization of 1,4‐alkynones to synthesize alkenyl cyclobutanols with a tetrasubstituted stereocenter. This strategy features a broad substrate scope, delivering a variety of trifluoromethyl‐containing rigid (spiro)carbocycle skeletons in good yields with high enantioselectivities (up to 84 % yield and 98.5 : 1.5 er). The synthetic utility is demonstrated through stereospecific transformations into fused spiro molecules. Experimental and computational mechanistic studies indicate that the reaction is initiated by an active Ni−H species, with carbonyl‐directed hydrometalation as the key for regioselective control. This catalytic method provides a general solution for regioselective hydrofunctionalization of alkynes and represents an efficient reaction pattern for assembling highly strained enantioenriched bioisosteres.

Access to Alkenyl Cyclobutanols by Ni-Catalyzed Regio- and Enantio-Selective syn-Hydrometalative 4-exo-trig Cyclization of Alkynones.

Enantioselective synthesis of (spiro)cyclobutane derivatives poses significant challenges yet holds promising applications for both synthetic and medicinal chemistry. We report here a nickel-catalyzed asymmetric syn-hydrometalative 4-exo-trig cyclization of 1,4-alkynones to synthesize alkenyl cyclobutanols with a tetrasubstituted stereocenter. This strategy features a broad substrate scope, delivering a variety of trifluoromethyl-containing rigid (spiro)carbocycle skeletons in good yields with high enantioselectivities (up to 84 % yield and 98.5 : 1.5 er). The synthetic utility is demonstrated through stereospecific transformations into fused spiro molecules. Experimental and computational mechanistic studies indicate that the reaction is initiated by an active Ni-H species, with carbonyl-directed hydrometalation as the key for regioselective control. This catalytic method provides a general solution for regioselective hydrofunctionalization of alkynes and represents an efficient reaction pattern for assembling highly strained enantioenriched bioisosteres.

Cardiovascular reactivity during conversations about discrimination is buffered by social support among U.S. Latines

Racial discrimination is conceptualized as an acute and chronic stressor. Like other acute stressors, lab-based studies demonstrate acute effects of discrimination-related stressors on stress-related cardiovascular outcomes, including total cardiac output, blood pressure, and indices of sympathetic and parasympathetic nervous system activity. Critically, it is important to understand how individual and social factors buffer the experience of race-related acute stress. The current study extends existing work by measuring cardiovascular indices of stress during conversations about racial/ethnic discrimination and examines the moderating role of social support. Latine/Hispanic participants (N = 97) talked about personal discrimination experiences with either a close other or a research assistant they had never previously met. Participants in both conditions exhibited cardiovascular reactivity indicative of stress during the conversation. Additionally, patterns of reactivity reflected a more adaptive stress response and recovery profile when participants talked about discriminatory experiences with a close other relative to a stranger (less parasympathetic withdrawal during the stressor and more parasympathetic rebound during recovery). These patterns are consistent with a stress buffering account of social support, which suggests social bonds and community-level support are critical to consider in interventions to mitigate the harms of experiencing discrimination and prevent chronic health disparities.

Electrochemical carboxylation: Green synthesis of atrolactic acid using boron-doped diamond electrodes

Electrochemical CO2 fixation is vital for sustainability in the chemical industry, yet the selective synthesis of multi-carbon products remains challenging. Organic electrosynthesis offers promise by enabling precise control over reaction conditions and facilitating novel reactivity patterns. One such technique, electrochemical carboxylation, involves coupling CO2 with organic molecules to produce carboxylic acids. Specifically, electro-carboxylation of acetophenone yields atrolactic acid, a valuable precursor for nonsteroidal anti-inflammatory drugs, providing a greener alternative to traditional production methods. This study focuses on the synthesis and characterization of boron-doped diamond (BDD) films using the microwave plasma-assisted chemical vapor deposition (MP-CVD) method and synthesized BDD electrodes were then used for the electrolytic carboxylation of acetophenone. Various analytical techniques, including X-ray diffraction (XRD), Raman spectroscopy, and laser microscopy, etc. were employed to characterize the BDD films. Various BDD films synthesized for different durations were utilized in the electrolytic carboxylation of acetophenone, with the highest yield of atrolactic acid (25 %) achieved using a BDD film synthesized over 6 h. Also, the effect of BDD surface modification i.e. oxygen and hydrogen terminated BDD on the synthesis of atrolactic acid was studied. Additionally, different electrolytes were employed in the synthesis process of atrolactic acid. A comparative study between Pt and BDD electrodes for the electrolytic carboxylation of acetophenone was conducted, and a mechanism for the formation of atrolactic acid was proposed.

Categorical and latent profile approaches to temperamental infant reactivity and early trajectories of socioemotional adjustment.

This article examines the patterns, and consequences, of infant temperamental reactivity to novel sensory input in a large (N = 357; 271 in current analysis) and diverse longitudinal sample through two approaches. First, we examined profiles of reactivity in 4-month-old infants using the traditional theory-driven analytic approach laid out by Jerome Kagan and colleagues, and derived groups characterized by extreme patterns of negative reactivity and positive reactivity. We then used a theory-neutral, data-driven approach to create latent profiles of reactivity from the same infants. Despite differences in sample characteristics and recruitment strategy, we noted similar reactivity groups relative to prior cohorts. The current data-driven approach found four profiles: high positive, high negative, high motor, and low reactive. Follow-up analyses found differential predictions of internalizing, externalizing, dysregulation, and competence trajectories across 12, 18, and 24 months of life based on 4-month reactivity profiles. Findings are discussed in light of the initial formulation of early reactivity by Kagan and the four decades of research that has followed to refine, bolster, and expand on this approach to child-centered individual differences. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Arts and psychomotor therapies in personality disorder treatment: An appropriate therapeutic entrance to personal development: A commentary.

Personality disorders (PD) are based not just on maladaptive ideas about self and others, they also are grounded on embodied patterns of behaviors and reactions to interpersonal stressors. There is growing interest in working with the body and through the body so to address automatisms that lead to suffering and dysfunctional social action. In this issue of the Journal of Clinical Psychology: In-Session the use of art and psychomotor therapies for these patients was explored by seven different clinical perspectives. Patients described presented with different PD and associated symptoms. The arts and psychomotor therapies deployed in personality disorder treatment are: (visual) art therapy, music therapy, drama therapy, dance (movement) therapy, and psychomotor therapy making psychotherapeutic use of the different modalities: art, music, play, role-play, performance, improvisation, dance, body awareness and movement. Interventions provide kinesthetic, sensory, perceptual, and symbolic opportunities to invite alternative modes of meaning-making, accessing own needs and wishes, and communicating them to others. In this commentary we summarize some of the different topics covered by the clinical-based papers, including working mechanisms of arts and psychomotor therapies, the importance of bottom-up emotion regulation processes, how to treat trauma in the presence of a PD, how to integrate art and psychomotor therapies in a fine-grained formulation and how to understand the process of change. Although there is a need for more empirical research, we hope this issue makes a solid case that clinicians can effectively include art and psychomotor therapies when treating the full range of PD.

Zoon balanitis: not a distinct clinicopathological entity?

Zoon balanitis (ZB) was originally described in the 1950s in patients with clinical features resembling erythroplasia of Queyrat, but with histology that demonstrated a plasma cell infiltrate without evidence of dysplasia. Subsequently, ZB has been extensively reported in the literature, reflecting widespread acknowledgement as an established distinct clinicopathological entity. However, its existence as such has been questioned and there have been suggestions in the literature that ZB represents either a non-specific irritant reaction pattern, or a part of the heterogenous clinicopathological complex of male genital lichen sclerosus (MGLSc). In this study, the entire historical literature of published cases of ZB was subject to review, to determine respectively whether clinical or histological features of MGLSc had been present and been overlooked. One hundred and one papers were reviewed. Seventy-five contained images purporting to be of ZB. Images that were deemed to be of inadequate quality or to present uninformative anatomical views were excluded. The images in 66 manuscripts were amenable to scrutiny; 98.5% of these images demonstrated clinical signs of MGLSc, such as adhesions, effacement of the coronal sulcus and the frenulum, tightening of the prepuce, constrictive posthitis, etiolation of the glans, lichenoid inflammation and sclerosis. These findings strongly suggest that ZB occurs in the vast majority of cases as a manifestation of MGLSc and that its recognition as a distinct clinicopathological entity should be questioned, if not discontinued.

Implications of respiratory sinus arrhythmia (RSA) inertia for child psychopathology: Direct effect and interaction with between-task RSA reactivity.

Respiratory sinus arrhythmia (RSA) inertia is the temporary dependency of RSA levels between consecutive epochs, which captures the epoch-to-epoch stickiness of RSA reactivity. Previous studies examining the developmental function of between-task RSA reactivity have yielded mixed findings and have often overlooked RSA reactivity within the task. The present study examined whether RSA inertia during a stress task was associated with subsequent changes in child psychopathology symptoms. To have a comprehensive understanding of the function of RSA reactivity, we tested whether RSA inertia interacted with between-task RSA reactivity to jointly predict changes in child psychopathology symptoms. Eighty-nine middle-to-high income Chinese parent-child dyads were recruited. Children (Mage = 8.77 years, SD = 1.80 years, 41 girls) participated in a 2-min resting phase and then a 4-min stress task (a public speaking task), during which RSA was continuously recorded in the lab. Parents (Mage = 39.27 years, SD = 3.53 years, 67 mothers) reported on children's psychopathology symptoms in the lab and again 9 months later. Children with heightened RSA inertia tended to exhibit increased externalizing symptoms 9 months later. Moreover, RSA inertia interacted with between-task RSA reactivity to predict subsequent changes in externalizing symptoms. Children with the combination of lower RSA inertia and larger between-task RSA decreases had the lowest externalizing symptoms, suggesting an adaptive RSA reactivity pattern. Heightened within-task RSA inertia as well as reduced between-task RSA reactivity may help to identify children at risk for subsequent psychopathology symptoms, aiding in early intervention efforts. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Enantioselective Cascade Reactions of Aminocatalytic Dienamines and Trienamines Initiated by a Cycloaddition Reaction.

Cycloadditions are widely accepted as a group of reactions that rapidly generate molecular complexity. Being highly atom economic and often predictable, these reactions can generate up to four stereogenic centers and two C-C (or C-X) bonds in one reaction step. During the last two decades, asymmetric aminocatalysis has shown to be a successful strategy for controlling stereoselectivity and enabling reactivity of cycloaddition reactions. By increasing the conjugation of the carbonyl species employed, dienamines and trienamines can be catalytically formed. Not only can these facilitate the cycloaddition, often accompanied by high levels of stereocontrol, but they also leave a residual enamine or carbonyl (by hydrolysis) in the cycloadduct. This residual functionality can engage in further intramolecular reactions generating complex cyclic systems in a one-pot cascade manner. In this regard, asymmetric aminocatalysis can add another layer of complexity to the already complex nature of cycloadditions. In this review, we will present the general concept of such reactivity patterns of dienamines and trienamines, and hereafter showcase examples in the literature. We aspire that the chemical community can use these concepts to design new enantioselective aminocatalytic cascade reactions to access enantioenriched, complex compounds, and perhaps use these in complex molecule synthesis.

Modulating Core Polarity in Metal-free Covalent Organic Frameworks for Selective Electrocatalytic Hydrogen Peroxide Production.

Tuning the charge density at the active site to balance the adsorption ability and reactivity of oxygen is extremely significant for driving a two-electron oxygen reduction reaction (ORR) to produce hydrogen peroxide (H2O2). Herein, we have highlighted the influence of intermolecular polarity in covalent organic frameworks (COFs) on the efficiency and selectivity of electrochemical H2O2 production. Different C3 symmetric building blocks have been utilized to regulate the charge density at the active sites. The benzene-cored COF, which exhibits reduced polarity than the triazine-cored COF, displayed enhanced performance in H2O2 production, achieving 93.1% selectivity for H₂O₂ at 0.4 V with almost two-electron transfer and a faradaic efficiency of 90.5%. In-situ electrochemical Raman spectroscopy and scanning electrochemical microscopy (SECM) were employed to confirm H₂O₂ generation and analyze spatial reactivity patterns. These techniques provided detailed insights into localized catalytic behavior, emphasizing the influence of core polarity.

Modulating Core Polarity in Metal‐free Covalent Organic Frameworks for Selective Electrocatalytic Hydrogen Peroxide Production

Tuning the charge density at the active site to balance the adsorption ability and reactivity of oxygen is extremely significant for driving a two‐electron oxygen reduction reaction (ORR) to produce hydrogen peroxide (H2O2). Herein, we have highlighted the influence of intermolecular polarity in covalent organic frameworks (COFs) on the efficiency and selectivity of electrochemical H2O2 production. Different C3 symmetric building blocks have been utilized to regulate the charge density at the active sites. The benzene‐cored COF, which exhibits reduced polarity than the triazine‐cored COF, displayed enhanced performance in H2O2 production, achieving 93.1% selectivity for H₂O₂ at 0.4 V with almost two‐electron transfer and a faradaic efficiency of 90.5%. In‐situ electrochemical Raman spectroscopy and scanning electrochemical microscopy (SECM) were employed to confirm H₂O₂ generation and analyze spatial reactivity patterns. These techniques provided detailed insights into localized catalytic behavior, emphasizing the influence of core polarity.

The influence of the homofermentative lactic acid bacteria and enzymes on the nutritional value, health safety, and aerobic deterioration of the different maize hybrid silages

The research aimed to determine the impact of identic inoculants of lactic acid bacteria (LAB) with enzymes (ENZ) on the silage quality of 5 different corn hybrids (Zea mays). Hybrids (Pioneer Hi-Bred DuPont) differed by FAO maturity group (from early H1, mid-early H2, medium H3, mid-late H4 to late H5). Inoculant LAB consisted of a mixture of homofermentative bacteria: Lactobacillus plantarum, Enterococcus faecium, Pediococcus acidilactici, Lactobacillus salivarius, and ENZ: cellulase, α- amylase, hemicellulase, xylanase. Ensiling was done at the laboratory conditions, where the green mass of corn hybrids has been inoculated with LAB and ENZ were added, before ensiling. The process of ensiling lasted 60 days. The addition of LAB inoculants with ENZ is frequently used to speed up the ensiling process, prevent the growth of harmful microorganisms, protect the aerobic stability of silage, and improve the silage quality of different crops. The phase of aerobic degradation of silage begins immediately after exposure to silage to air. This stage is inevitable during feeding with silage and takes place in all silages, regardless of quality. The same pattern of reaction on identic LAB and EFEs addition was not found in silages ensiled from different hybrids. Among the evaluated corn hybrids, the additive to H1 early maturity hybrid had significantly improved the silage quality, and prolonged the time of aerobic stability, mainly due to the significantly highest CP, lowest ADL, and highest LA content. The chemical composition, fermentation, and microbiology profiles of silage significantly influence CO2 production in a test of aerobic stability (AS), and this is a causal relationship of aerobic stability duration. The results of this trial showed that the lower butyric acid, total microorganisms number, count of yeasts and mold, pH, and higher LAB, lactic acid, and acetic acid levels (P<0.05), are accompanied by the production of lower CO2 (P<0.05). The current research and previous studies suggest that nutritional value, health safety, and aerobic deterioration of the different maize hybrid silages are under the influence of epiphytic microflora of ensiled plants, used LAB inoculum, and EFEs addition in the appropriate amount, and the type of hybrid ensiled as well.

Comparison of MIB-1-Specific Membrane Staining in Hyalinising Trabecular Tumor Using Mainstream Automated Immunohistochemical Staining Platforms.

MIB-1, a monoclonal antibody against Ki-67, exhibits specific membrane staining in the immunohistochemistry of hyalinising trabecular tumor (HTT). This specific staining pattern is crucial in diagnosing HTT. Although manual immunohistochemical staining remains the established method for MIB-1 staining, this process is complicated, inconsistent, and prone to false negatives. This study aimed to explore whether the classical reaction pattern can be replicated by utilizing the current mainstream automated immunohistochemical staining platforms. Furthermore, we examined the effect of different conditions on staining efficiency and their value in clinical diagnosis assistance. Specimens obtained from eight and six cases of HTT and non-HTT, respectively, from a single center were stained using the manual staining method and the Dako Autostainer Link 48 (AS48), Dako Omnis, Ventana BenchMark ULTRA, and Leica BOND-III automated immunohistochemical staining platforms. The Autostainer Link 48 was found to be the most stable staining platform, while the BenchMark ULTRA with primary antibody incubation at room temperature (RT) and the Omnis platform with antigen retrieval at pH 9.0 were able to reproduce membrane-positive staining for MIB-1 in the HTT specimens. Our results offer crucial reference value for clinical diagnostic assistance.

Iodine(III)-Mediated Photochemical C-H Azolation.

A systematic radical polarity analysis framework is formulated herein for the projection of radical reactivity patterns. An iodine(III)-mediated photochemical C-H azolation reaction has been envisaged and developed based on the set of empirical guidelines. The synthesis features an environmentally benign reagent, mild reaction conditions, an operationally simple protocol, and a broad substrate scope. The inclusive demonstration of reactivity for ether, thioether, amide, benzylic, and allylic C-H bonds promises wide-ranging synthetic utility.