Light-Induced Increase in Bond Strength─from Chalcogen Bond to Three-Electron σ Bond upon Excitation

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 7, 2025

Chalcogen bonds are σ hole interactions between a chalcogen center and Lewis base have been applied in recent years as an alternative to hydrogen supramolecular chemistry catalysis. While the electronic of ground state intensively analyzed, there is barely any knowledge about electron structure excited state. This despite fact that some cases photoswitches containing exhibit exceptional switching behavior. Here, we investigate effect light absorption on divalent centers. Quantum chemical calculations reveal S1 noncovalent bond converts covalent three-electron bond. The thus significantly reinforced by excitation. change type explains previously experimentally observed nonswitchability tellurium-containing azo compounds. Furthermore, were able demonstrate switchability certain selenium-containing compounds temperature-dependent, whereby ratio less stable cis compound higher for temperatures. These results highlight potential designing responsive materials dynamic molecular systems based light-induced modulation.

Language: Английский

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A Fluorogenic Substrate for Quinoline Reduction: Pnictogen‐Bonding Catalysis in Aqueous Systems

Helvetica Chimica Acta, Journal Year: 2024, Volume and Issue: 107(5)

Published: March 6, 2024

Abstract It is often said that pnictogen‐bonding catalysis, and σ ‐hole catalysis in general, would not work aqueous systems because the solvent interfere as an overcompetitive pnictogen‐bond acceptor. In this study, we show transfer of from hydrophobic solvents to possible by replacing only with hydrophilic substrates, without changing catalyst or reaction. This differs conventional covalent Lewis acid catalysts, which are instantaneously destroyed ligand exchange. With their water‐proof substituents place exchangeable ligands, supramolecular counterpart evinced catalyze hydrogenation quinolines neutral systems. To secure these results, introduce a water‐soluble fluorogenic substrate releases coumarin upon reduction instead activated quinolidiniums, stiborane catalysts deepened holes. They demonstrate can operate higher‐order architectures for under biologically relevant conditions, provide operational assay high‐throughput screening fluorescence imaging, situ conditions.

Language: Английский

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Core‐Alkynylated Fluorescent Flippers: Altered Ultrafast Photophysics to Track Thick Membranes

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(31)

Published: May 17, 2024

Fluorescent flippers have been introduced as small-molecule probes to image membrane tension in living systems. This study describes the design, synthesis, spectroscopic and imaging properties of that are elongated by one two alkynes inserted between push pull dithienothiophene domains. The resulting mechanophores combine characteristics flippers, reporting on physical compression ground state, molecular rotors, torsional motion excited take their photophysics new level sophistication. Intensity ratios broadened excitation bands from differently twisted conformers core-alkynylated thus report mechanical compression. Lifetime boosts ultrafast excited-state planarization lifetime drops competitive intersystem crossing into triplet states viscosity. In standard lipid bilayer membranes, too long for leaflet tilt or extend disordered interleaflet space, which preserves rotor-like disorder weak, blue-shifted fluorescence. Flipper-like occurs only highly ordered membranes matching thickness, where they light up selectively these thick with red-shifted, sharpened maxima, high intensity lifetime.

Language: Английский

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Pnictogen‐Bonding Enzymes

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(45)

Published: July 5, 2024

Abstract The objective of this study was to create artificial enzymes that capitalize on pnictogen bonding, a σ‐hole interaction is essentially absent in biocatalysis. For purpose, stibine catalysts were equipped with biotin derivative and combined streptavidin mutants identify an efficient transfer hydrogenation catalyst for the reduction fluorogenic quinoline substrate. Increased catalytic activity from wild‐type best coincides depth σ hole Sb(V) center, emergence saturation kinetic behavior. Michaelis–Menten analysis reveals transition‐state recognition low micromolar range, more than three orders magnitude stronger millimolar substrate recognition. Carboxylates preferred by contribute hydrogen‐bonded ion pairing anion‐π interactions emerging pyridinium product. challenging stereoselectivity aqueous systems further emphasizes compatibility bonding higher order catalysis.

Language: Английский

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Neutral Chalcogen Bonding Enabled Photoinduced Cross‐Electrophile C—S/Se Coupling of Aryl Iodides via S_RN1 Process

Chinese Journal of Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 7, 2025

Comprehensive Summary Cross‐coupling reactions between aryl halides and thiolates or selenolates typically require transition metals, photocatalysts, strong bases, or/and malodorous thiols/selenols, with various mechanisms proposed. This study aims to leverage a new application of neutral ChB address these challenges enable very simple photoinduced cross‐electrophile C—S/Se coupling using readily available chalcogen electrophiles. Mechanistic investigations have revealed the important role in facilitating single electron transfer processes, thereby enabling generation thiolates/selenolates from stable electrophiles α ‐aminoalkyl radicals, which possess capability abstract halogen atoms iodides. Moreover, provided support for radical nucleophilic substitution mechanism.

Language: Английский

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Hydrophobic Interfacing of Fluorescent Membrane Probes

ChemistryEurope, Journal Year: 2023, Volume and Issue: 1(3)

Published: Oct. 2, 2023

Abstract Fluorescent flippers have been introduced as small‐molecule probes to image membrane tension in living systems. While the hydrophilic headgroup region has modified extensively for intracellular targeting, little is known about hydrophobic interfacing with surrounding membrane. To tackle this challenge, design, synthesis and evaluation of a glutamine‐derived flipper collection reported. Considering importance tension‐induced phase separation imaging, study focused on how modulate distribution functional between ordered disordered microdomains. Also interest was control over intermembrane transfer without loss function specific labeling plasma membranes. Evidence presented two‐step insertion mechanism through more accessible domains into better matching domains. This process also explains differences partition coefficients bioimaging. It further demonstrated that interdomain can be regulated by brightness fluorescence lifetime imaging microscopy responsiveness tension. Irreversible partitioning inhibits coincides internalization cells. These results demonstrate improve probe performance provide guidelines proceed.

Language: Английский

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Pnictogen‐Bonding Enzymes

Angewandte Chemie, Journal Year: 2024, Volume and Issue: 136(45)

Published: July 5, 2024

Abstract The objective of this study was to create artificial enzymes that capitalize on pnictogen bonding, a σ‐hole interaction is essentially absent in biocatalysis. For purpose, stibine catalysts were equipped with biotin derivative and combined streptavidin mutants identify an efficient transfer hydrogenation catalyst for the reduction fluorogenic quinoline substrate. Increased catalytic activity from wild‐type best coincides depth σ hole Sb(V) center, emergence saturation kinetic behavior. Michaelis–Menten analysis reveals transition‐state recognition low micromolar range, more than three orders magnitude stronger millimolar substrate recognition. Carboxylates preferred by contribute hydrogen‐bonded ion pairing anion‐π interactions emerging pyridinium product. challenging stereoselectivity aqueous systems further emphasizes compatibility bonding higher order catalysis.

Language: Английский

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Fluorescent Membrane Probes Obey the Israelachvili Rules

Helvetica Chimica Acta, Journal Year: 2024, Volume and Issue: 107(7)

Published: May 9, 2024

Abstract When developing fluorescent membrane probes, we naturally tend to focus on the fluorophore itself. In this study, show that sometimes it can be beneficial shift attention from center periphery, maximize multiple interfacing with complex changing environments. Palmitylation for hydrophobic and glutamate dendrons hydrophilic are combined improve performance of flipper probes. We increase in membranes, solubility water is important, water, hydrophobicity probe. These seemingly paradoxical measures taken satisfy Israelachvili rules. They state only inverted cone amphiphiles form soluble micelles while shaped precipitate into hexagonal 1 supramolecular polymers, intermediate cylindrical behavior dominated by bilayers lamellar precipitates. The normal obtained prevent precipitation prepare efficient transfer lipid bilayer membranes. results flippers break all records set 2016 original regard effective brightness, responsiveness order, anchoring disordered partitioning membranes high stable labeling interest. lessons learned confirm obvious: rules apply also promise literally bright perspectives

Language: Английский

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Core‐Alkynylated Fluorescent Flippers: Altered Ultrafast Photophysics to Track Thick Membranes

Angewandte Chemie, Journal Year: 2024, Volume and Issue: 136(31)

Published: May 17, 2024

Abstract Fluorescent flippers have been introduced as small‐molecule probes to image membrane tension in living systems. This study describes the design, synthesis, spectroscopic and imaging properties of that are elongated by one two alkynes inserted between push pull dithienothiophene domains. The resulting mechanophores combine characteristics flippers, reporting on physical compression ground state, molecular rotors, torsional motion excited take their photophysics new level sophistication. Intensity ratios broadened excitation bands from differently twisted conformers core‐alkynylated thus report mechanical compression. Lifetime boosts ultrafast excited‐state planarization lifetime drops competitive intersystem crossing into triplet states viscosity. In standard lipid bilayer membranes, too long for leaflet tilt or extend disordered interleaflet space, which preserves rotor‐like disorder weak, blue‐shifted fluorescence. Flipper‐like occurs only highly ordered membranes matching thickness, where they light up selectively these thick with red‐shifted, sharpened maxima, high intensity lifetime.

Language: Английский

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Asparagusic Golgi Trackers

JACS Au, Journal Year: 2024, Volume and Issue: 4(10), P. 3759 - 3765

Published: Aug. 20, 2024

Thiol-mediated uptake (TMU) is thought to occur through dynamic covalent cascade exchange networks. Here we show that the accounting for TMU of asparagusic acid derivatives (AspA) ends in Golgi apparatus (G) and shifts from disulfide thioester with palmitoyl transferases as final partner. As a result, AspA combined pH-sensitive fluoresceins, red-shifted silicon-rhodamines, or mechanosensitive flipper probes selectively labels fluorescence microscopy images living fixed cells. trackers work without cellular engineering excel speed, simplicity, generality, compatibility G/ER cis/trans discrimination, morphological changes, anterograde vesicular trafficking, superresolution imaging by stimulated emission depletion microscopy. flippers particular can image membrane order tension and, if desired, at plasma during TMU.

Language: Английский

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