Mechanistic Insight into Para-Substituent Control of Thermal Half-Lives in Arylazopyrazole Photoswitches.

Arylazopyrazoles are versatile photoswitches with excellent photochromic properties and tunable thermal half-lives, yet the mechanistic role of substituents in controlling thermal stability remains poorly understood. Here, we synthesized an extensive library of arylazo-1,3,5-trimethylpyrazole photoswitches and rationalized the influence of para-substituents on the thermal half-lives, finding excellent agreement between calculated and measured trends. Calculations show that the electron-donating and electron-withdrawing nature of the substituents modulates the back-isomerization process through at least two distinct mechanisms.

Borane-functionalized heteroscorpionate copper complexes as catalysts for azide-alkyne cycloaddition.

In this work, new copper(I) complexes of borane-functionalized bis(3,5-dimethylpyrazolyl)methane ligands were synthesized, characterized and used as catalysts for the cycloaddition of phenylacetylene and azides. Reaction of the allylated bis(3,5-dimethylpyrazolyl)methane proligand (La) with CuCl or [Cu(NCMe)]BF gave rise to the neutral copper chloride complex [(La)CuCl] (1a) or the binuclear cationic copper complex [(La)Cu(NCMe)]2(BF4)2 (2a2), respectively. The same reactions using a borane-functionalized bis(3,5-dimethylpyrazolyl)methane proligand (Lb) led to the isolation of complexes [(Lb)CuCl] (1b) and [(Lb)Cu(NCMe)2]BF4 (2b).

Investigation of Lewis photobase-catalysed oxa-Michael addition for hot lithography.

In lithography-based additive manufacturing, step-growth polymerization is a highly desired mode as the resulting polymer networks are usually more homogenous and therefore tougher than ones obtained by free radical chain growth polymerization. Therefore, thiol-ene chemistry sees widespread use, however, the employed thiols are accompanied by strong odor, limited availability and limited storage stability of the formulation. Replacing the thiols with alcohols resolves these problems as a wide variety of odorless alcohols is available.

Detoxification of deoxynivalenol by pathogen-inducible tau-class glutathione transferases from wheat.

Deoxynivalenol (DON) is a toxicologically relevant trichothecene mycotoxin frequently found in cereal products. It is a virulence factor produced by the plant pathogen Fusarium graminearum during cereal crop infections. Investigating plant defense mechanisms is crucial for understanding plant resistance to F.

Co-enzyme-free, enzymatic synthesis of aldehydes from renewable resources with a new and highly efficient alkene cleaving dioxygenase.

Alkene cleaving dioxygenases (ADO), which can oxidatively cleave C[double bond, length as m-dash]C double bonds to the respective carbonyl compounds, may aid in waste stream utilization strategies by valorizing lignin-derived monomers. Here, we present 11 new ADOs and describe the characteristics of the most promising candidate ADO from . ADO shows unprecedented reaction kinetics and a high yield without requiring co-enzymes or co-substrates other than O.

Combined Inductive and Dispersion Effects Enhance Bioorthogonal Reactivity of Tetrazines Toward Isonitriles.

Inverse-electron demand cycloaddition reactions of tetrazines are widely used in bioorthogonal chemistry, but the opposing effects of substituents on reactivity and stability make optimizing tetrazines for chemical biology applications challenging. Building on the discovery that bulky substituents can unexpectedly enhance both the stability of tetrazines and their reactivity toward isonitriles, we hypothesized that substituents that are both bulky and electron-withdrawing could yield tetrazines with desirable properties. We synthesized a series of tetrazines designed to explore these kinetic properties.

Producing mixed linked xylooligosaccharides from red algae biomass through single-step enzymatic hydrolysis.

Background: The red alga Palmaria palmata is a rich source of sugar compounds, particularly mixed-linkage xylans present in the cell walls of the algae. In contrast to their terrestrial lignocellulosic counterparts, these xylans are more easily accessible. They can be hydrolyzed enzymatically into valuable xylooligosaccharides (XOS), known for their prebiotic, antioxidant, and immunomodulatory properties.

Structural and Functional Characteristics of Potent Dioxygenase from .

Enzymatic C=C double bond cleavage to give carbonyl-species is an emerging alternative to ozonolysis, or stoichiometric use of metal-oxidants. The substrate scope of 4-His Fe dioxygenases, however, appears to be restricted to aromatic compounds with a hydroxy group at the 4-position of the aromatic ring. In-depth structural and functional characterization is a prerequisite to understand and ultimately to extend the substrate scope of this family of enzymes.

Autologous and synthetic vascular grafts trigger different host responses in the anastomotic regions and in the perivascular adipose tissue during the early healing phase.

Interactions between tissue and material post-implantation significantly impact the long-term behavior of vascular prostheses. Autologous materials are preferred for replacing small-diameter blood vessels due to their superior healing properties compared to synthetic options. This study aimed to characterize the host response to autologous and various synthetic grafts and during the early healing phase, focusing on anastomotic regions and perivascular adipose tissue (PVAT).

Selectively counteracting cerebellar adaptations to chronic alcohol exposure reduces acute alcohol withdrawal severity in C57BL6/N mice.

A critical component of Alcohol Use Disorder (AUD) is alcohol (EtOH) withdrawal and consequent aversive withdrawal symptoms that generate negative reinforcement for renewed EtOH consumption to alleviate such symptoms. Here, we simulated human binge EtOH consumption and subsequent acute withdrawal by exposing male and female C57BL6/N mice to EtOH vapor for varying durations (24-72 h). During acute withdrawal, starting 4 h after removal from EtOH vapor, we used patch-clamp recording in cerebellar slices, combined with behavioral analysis of aversive somatic/motor (performance on the accelerating rotorod) and affective/emotional (ultrasonic vocalizations and blood corticosterone) withdrawal symptoms.

Building a Medicinal Chemistry Framework for Bioorthogonal Probes.

Screening the tetrazine-protein interactome finds the balance needed for high-performance fluorescent probes.

An Animal-Free Patient-Derived Tissue-Mimetic Biochip Model of the Human Synovial Membrane for Human-Relevant Osteoarthritis Research.

Current synovial models fail to capture human-relevant OA traits. This study develops a fully humanized, animal-free synovial membrane model, mimicking OA synovial structure and molecular profile. Protocols for rheumatoid synovial micromasses are adapted for 3D biochip cultures of OA synoviocytes using TISSEEL fibrin and ELAREM lysate.

Heating of dental composites: The crucial role of the silane coupling agent on the consistency change.

Objective: To evaluate the influence of the nature of silane coupling agents on the consistency of dental composites at various temperatures.

Methods: Silanes SI 1-4 were synthesized in one single step. They were characterized by H and C NMR spectroscopy.

Ru-Catalyzed Mechanochemical Trifluoromethylation of Arylboronic Acids and Phenols by in Situ-Generated N-Trifluoromethylpyridinium Salt as CF Source.

We report a mechanochemical approach for the ruthenium catalyzed trifluoromethylation of arylboronic acids and phenols under the synergy of trifluoromethylacetamide and pyrylium tetrafluoroborate (Pyry-BF₄). This is the first ever report on trifluoromethylation using in situ generated N-trifluoromethylpyridinium tetrafluoroborate as the CF source under ball-milling conditions. The present one-pot transformation enabled direct trifluoromethylation of arylboronic acids and phenols to deliver the respective trifluoromethyl arenes and aryl trifluoromethyl ethers.

Click-Triggered Bioorthogonal Bond-Cleavage Reactions.

Bioorthogonal bond-cleavage reactions have evolved into powerful tools for chemical biology, representing a promising strategy for achieving controlled release of molecules under physiologically relevant conditions, even in living organisms. Since their discovery, significant efforts have been invested in the development and understanding of the underlying chemistries to enhance the click-to-release performance, biocompatibility, and stability of bioorthogonal tools. In this review, we aim to provide a concise overview of click-triggered bioorthogonal bond-cleavage reactions, with an emphasis on the mechanisms and characteristics of the most commonly applied click-to-release chemistries.

Synthesis, Characterization and Catalytic Activity of Iron, Cobalt and Nickel Complexes Bearing an N‑Heterocyclic Carbene-Based PCP Pincer Ligand.

Reactions of the bis-((Rphosphanyl)-methyl)-1-benzo-[]-imidazole-3-ium hexafluorophosphate precursors [(PCP-R)-H]-PF (R = Pr, Ph) with zerovalent precursors [Fe(CO)], [Co(CO)], [Ni-(COD)] and [Ni-(PPh)], respectively, gave rise to the cationic iron, cobalt and nickel complexes [Fe-(PCP-Pr)-(CO)H]-PF (), [Co-(PCP-Pr)-(CO)]-PF (), [Co-(PCP-Ph)-(CO)]-PF (), [Ni-(PCP-Pr)-(cyclooct-4-en-1-yl)]-PF () and [Ni-(PCP-Pr)-H]-PF (), by oxidative addition of the benzimidazolium CH bond in [(PCP-R)-H]-PF. The complexes bearing the bidentate ligand 3-((diisopropylphosphanyl)-methyl)-1-methyl-1H-benzo-[]-imidazolidene PC-Pr [Fe-(PC-Pr)-(CO)] () and [Fe-(PC-Pr)-(CO)H]-BF () were also synthesized. All complexes were characterized by NMR and FTIR spectroscopies, high resolution mass spectrometry and selected cases by single-crystal X-ray diffraction.

Ultrahigh-Throughput Activity Engineering of Promiscuous Amidases through a Fluorescence-Activated Cell Sorting Assay.

Ultrahigh-throughput methods such as flow cytometry are ideal tools for the directed evolution of enzymes by enabling the screening of up to 10 variants per day. In this study, we developed an assay based on fluorescence-activated cell sorting (FACS) for the detection and engineering of amidase activity in whole cells. The assay establishes a stable genotype-phenotype linkage by coupling coumarin-based hydrolysis products to intracellular glutathione via a recombinantly coexpressed glutathione -transferase.

-Cyclooctene-caged-IL-1β immunocytokine-constructs ligated to unmodified nanobodies allow click-2-release-based control of cytokine activity.

Immunocytokines have emerged as a promising modality in cancer therapy, capitalizing on the precision of antibodies to deliver cytokines selectively to tumours. Yet, the toxicity of the cytokine portion of these antibody-cytokine constructs remains a major dose-limiting issue. We present a new approach to control cytokine function without affecting binding of the targeting moiety.

Concealed antiaromaticity.

The literature reports numerous molecules claimed to be antiaromatic because of a formal 4 π-electron system. However, this neglects the actual local aromaticity of the molecules, which often feature multiple subunits with [4 +2] π-electrons besides the formal 4 π-electron system. This has led to considerable criticism from those who believe that the term antiaromatic should not be used for any molecule with a formal 4 π-electron system but should be reserved for truly antiaromatic molecules.

Polysaccharide-based green flocculants: A systematic and comparative study of their coagulation-flocculation efficiency.

Driven by the quest for greener flocculants, this study explores how cationized polysaccharides can enhance coagulation-flocculation efficiency, filling a gap in systematic comparative analyses. We introduce here a flocculation score which provides a robust framework for flocculation evaluation and comparison. Starch, chitosan, inulin, guar gum, pullulan, and hydroxyethyl cellulose were tested, both unmodified and modified with quaternary ammonium compounds.

Synthesis and Application of PN-Supported Mn(I) Carbonyl Alkyl Complexes.

This work comprises the synthesis and characterization of aminophosphine (PN)-derived Mn(I) carbonyl complexes and the preliminary investigation of their alkylated congeners for catalytic applications. The complexes -[Mn(PN)(CO)Br] are obtained from the reaction of Mn(CO)Br with the bidentate ligand PN = RN(CH)PR', where R = Me, Et, and pyrrolidine and R' = Ph, Pr, and Cy. Treatment of -[Mn(PN)(CO)Br] with AgOTf yields -[Mn(PN)(CO)OTf].

Highlighting the Influence between Physical and Chemical Cross-Linking in Dynamic Hydrogels for Two-Photon Micropatterning.

Photolabile hydrogels have gained tremendous interest for a wide range of applications in materials and life sciences. Usually, photodegradability is introduced via chromophores and labile bonds, making such materials intrinsically light sensitive. In recent years, disulfide bonds have emerged as an innovative alternative, as they can be selectively cleaved in the presence of (photo)generated radicals.

Advances in Mechanochemical Methods for One-Pot Multistep Organic Synthesis.

Mechanochemical synthesis has emerged as a powerful and more sustainable alternative to conventional solution-based methods, offering advantages such as no or only minimal solvent use, reduced reaction times, and simplified operational conditions. The integration of multiple steps into a single reaction vessel further enhances these benefits by eliminating workup and purification steps, reducing waste, and often improving overall efficiency. This review highlights recent advancements in mechanochemical one-pot multistep reactions in organic synthesis, focusing on protocols with sequential one-pot operation.

Careful Examination of a Novel Azobenzene Paroxetine Derivative and Its Interactions With Biogenic Amine Transporters.

The serotonin transporter (SERT) belongs to the family of neurotransmitter sodium symporters (NSS), together with other neurotransmitter transporters for norepinephrine, dopamine, glycine, and GABA. The main physiological role of SERT is the retrieval of previously released serotonin from the synaptic cleft. Thereby, SERT plays an important role in regulating the extracellular serotonin concentration and maintaining serotonergic neurotransmission.