An All-Organic Photochemical Magnetic Switch with Bistable Spin States

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(19), P. 8707 - 8716

Published: May 6, 2022

Controlling the electronic spin state in single molecules through an external stimulus is of interest developing devices for information technology, such as data storage and quantum computing. We report synthesis operation mode two all-organic molecular spin-state switches that can be photochemically switched from a diamagnetic [electron paramagnetic resonance (EPR)-silent] to (EPR-active) form at cryogenic temperatures due reversible electrocyclic reaction its carbon skeleton. Facile synthetic substitution configurationally stable 1,14-dimethyl-[5]helicene with radical stabilizing groups 4,11-positions afforded 4,11-dioxo or 4,11-bis(dicyanomethylidenyl) derivatives closed form. After irradiation LED light source temperatures, readily obtained, making this system bistable magnetic switch reversibly react back thermal stimulus. The switching monitored UV/vis spectroscopy EPR induced by electrochemical reduction reoxidation. Variable-temperature species revealed open-shell triplet ground experimentally determined triplet-singlet energy gap ΔET-S < 0.1 kcal mol-1. inherent chirality ability separate enantiomers turns helical motif into potential chiroptical switch. herein developed 4,11-substitution pattern on dimethyl[5]helicene introduces platform designing future generations organic photomagnetic might find applications spintronics related fields.

Language: Английский

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Octopi Tentacles‐Inspired Architecture Enables Self‐Healing Conductive Rapid‐Photo‐Responsive Materials for Soft Multifunctional Actuators

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 34(6)

Published: Oct. 22, 2023

Abstract To mimic biological systems' healing mechanism and sensory motion, the combination of self‐healing, perception, actuation in a singular soft artificial material is required, which would be enormously valuable for robotics that commit to obtaining multifunction local sensing capacities approaching living organisms. However, most existing somatosensory actuators lack self‐healing capability injuries, suffer from insufficient actuating performance sensitivity, complicated manufacturing operations. Herein, bioinspired conductive photo‐responsive architecture reported. Rapidly anthracene, matrix with dynamic interactions, high‐conductivity slideable silver nanowires chemically integrated are respectively utilized neuromuscular system effectors, tissue systems, nerve cords receptors octopus tentacles. Such actuator exhibits rapid (light‐driven bending velocity, 10 o s −1 ), distinctive intrinsic strain sensitivity (gauge factor, 90.88), decent efficiency (92.2%). As proof concept, octopi tentacles‐inspired smart grippers fabricated various motions including bending, weightlifting object grasping can contemporaneously detect actions by real‐time resistance changes provide information feedback. This work anticipated bring fresh horizons design multifunctional materials establish pathway advancement self‐diagnostic robots.

Language: Английский

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Carbon-based Biradicals: Structural and Magnetic Switching

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(24), P. 13952 - 13965

Published: Nov. 10, 2023

Sterically hindered C═C double bonds often deform into a bent or twisted geometry. Thus, many overcrowded ethylenes anthraquinodimethanes can adopt multiple conformations, such as folded form form, which are interconvertible under the application of external stimuli. A perpendicular with biradical character also be adopted when designed to incorporate stable carbon-based radical unit, is involved in stimuli-responsive magnetic switching accompanied by structural change. This review focuses on recent advances development strained π-electron systems and reveals factors that affect mutual interconversion behavior. The energy barrier for conformational isomers affected tricyclic skeleton bulky substituents bonds, whereas relative stability increases additional insertion 9,10-anthrylene units bonds.

Language: Английский

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Alternant Hydrocarbon Diradicals as Optically Addressable Molecular Qubits

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(22), P. 15549 - 15561

Published: May 27, 2024

High-spin molecules allow for bottom-up qubit design and are promising platforms magnetic sensing quantum information science. Optical addressability of molecular electron spins has also been proposed in first-row transition-metal complexes via optically detected resonance (ODMR) mechanisms analogous to the diamond-nitrogen-vacancy color center. However, significantly less progress made on front metal-free molecules, which can deliver lower costs milder environmental impacts. At present, most luminescent open-shell organic π-diradicals, but such systems often suffer from poor ground-state characters necessary realize a stable qubit. In this work, we use alternancy symmetry selectively minimize radical–radical interactions ground state, generating π-systems with high diradical characters. We call them m-dimers, referencing need covalently link two benzylic radicals at their meta carbon atoms desired symmetry. Through detailed electronic structure analysis, find that excited states alternant hydrocarbon m-diradicals contain important symmetries be used construct ODMR leading spin polarization. The parameters set context tris(2,4,6-trichlorophenyl)methyl (TTM) radical dimer tethered position, demonstrating feasibility as centers.

Language: Английский

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Enhancing the Optically Detected Magnetic Resonance Signal of Organic Molecular Qubits

ACS Central Science, Journal Year: 2025, Volume and Issue: 11(1), P. 116 - 126

Published: Jan. 3, 2025

In quantum information science and sensing, electron spins are often purified into a specific polarization through an optical-spin interface, process known as optically detected magnetic resonance (ODMR). Diamond-NV centers transition metals both excellent platforms for these so-called color centers, while metal-free molecular analogues also gaining popularity their extended lifetimes, milder environmental impacts, reduced costs. our earlier attempt at designing such organic high-spin π-diradicals, we proposed to spin-polarize by shelving triplet MS = ±1 populations singlets. This was recently verified experiments albeit with low ODMR contrasts of <1% temperatures above 5 K. this work, propose improve the signal moving singlet back 0 sublevel, true carbon-based analogue NV center. Our proposal is based upon transition-orbital group-theoretical analyses beyond-nearest-neighbor spin–orbit couplings, which further confirmed ab initio calculations realistic trityl-based radical dimer. Microkinetic point toward high around 30% under experimentally feasible conditions, stark improvement from previous works. Finally, in quest ground-state addressable spin qubits, exemplify how symmetry-based design avoids Zeeman-induced singlet–triplet mixings, setting scene realizing qubit gates.

Language: Английский

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Thiele’s Fluorocarbons: Stable Diradicaloids with Efficient Visible-to-Near-Infrared Fluorescence from a Zwitterionic Excited State

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(29), P. 15702 - 15707

Published: July 11, 2023

Thiele's hydrocarbon was the first synthesized diradicaloid in search for stable open-shell structures, but it remains sensitive to oxygen and light. We here report synthesis of fluorocarbon (TFC) its derivatives exhibiting exceptional thermal, oxidative, photostability. TFCs have remarkable luminescent properties with yellow NIR fluorescence up 100% quantum yields. X-ray crystallography ESR spectroscopy confirm their closed-shell quinoidal ground state. As expected from symmetric nonpolar structure, TFCs' absorption spectra show no solvent effect, emission reveals an extraordinarily large Stokes shift which increases polarity (from 0.9 eV cyclohexane 1.5 acetonitrile). that this behavior is a result sudden polarization, leading zwitterionic excited

Language: Английский

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Dibenzotropylium-Capped Orthogonal Geometry Enabling Isolation and Examination of a Series of Hydrocarbons with Multiple 14π-Aromatic Units

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(4), P. 2596 - 2608

Published: Jan. 6, 2023

A series of six dications composed pure hydrocarbons with one to non-substituted 9,10-anthrylene units end-capped two dibenzotropyliums were designed and synthesized elucidate the electronic properties huge oligo(9,10-anthrylene) backbones. Their structures successfully determined by X-ray analyses even in case eight planar 14π-electron units, revealing that all adopt almost orthogonally twisted between neighboring units. Spectroscopic voltammetric show neither significant overlap orbitals nor delocalization electrons occurs due geometry solution. As a result, sequential oxidation processes observed reversible formation multivalent cations release same number as anthrylene Upon two-electron reduction, closed-shell butterfly-shaped form was obtained from dication containing unit, whereas open-shell biradicals isolated stable entities cases derivatives three Notably, derivative metastable isomer quantitatively underwent slow thermal conversion most (Ea = 23.1 kcal mol-1). There is drastic change potentials neutral species (ΔE 1.32 V CH2Cl2). Since present regenerated upon reduction products, these systems may contribute development advanced response capable switching color, magnetic properties, oxidative using "cation-capped orthogonal geometry".

Language: Английский

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Redox-Switchable Aromaticity in a Helically Extended Indeno[2,1-c]fluorene

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(28), P. 19168 - 19176

Published: July 2, 2024

Molecular switches have received major attention to enable the reversible modulation of various molecular properties and been extensively used as trigger elements in diverse fields, including machines, responsive materials, photopharmacology. Antiaromaticity is a fascinating property that has attracted not only significant fundamental interest but also increasingly relevant different applications, particular organic (opto)electronics. However, designing systems which (anti)aromaticity can be judiciously reversibly switched ON OFF remains challenging. Herein, we report helicene featuring an indenofluorene-bridged bisthioxanthylidene novel switch wherein simultaneous two-electron (electro)chemical redox process allows highly its (anti)aromatic character. Specifically, two thioxanthylidene rotors, attached initially aromatic indenofluorene scaffold via overcrowded alkenes, adopt anti-folded structure, upon oxidation convert singly bonded, twisted conformations. This associated with (chir)optical changes importantly results formation fully conjugated, formally antiaromatic as-indacene motif helical core switch. proceeds without buildup radical cation intermediates thus enables switching geometry, aromaticity, absorbance, chiral expression under ambient conditions, evidenced by NMR, UV–vis, CD, (spectro)electrochemical analyses, supported DFT calculations. We expect this concept extendable wide range robust antiaromatic–aromatic provide basis for structure these inherently polycyclic π-scaffolds.

Language: Английский

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Exceptionally flexible quinodimethanes with multiple conformations: polymorph-dependent colour tone and emission of crystals

Materials Chemistry Frontiers, Journal Year: 2023, Volume and Issue: 7(8), P. 1591 - 1598

Published: Jan. 1, 2023

Tetraazaanthraquinodimethanes can exhibit various colours and emissions depending on their multiple conformations, such as not only folded twisted forms but also intermediate structures, e.g. , planar twisted-folded forms, in pseudopolymorphs.

Language: Английский

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Thermal Equilibrium Between Quinoid/Biradical Forms Enhancing Electrochemical Amphotericity

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(35)

Published: April 22, 2024

Upon dibenzo annulation on Thiele's hydrocarbon (tetraphenyl-p-quinodimethane), the quinoid form and biradical adopt quite different geometries, thus are no longer resonance structures. When these two forms can interconvert rapidly due to small energy barrier (ΔG

Language: Английский

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