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Search for "thermal isomerisation" in Full Text gives 3 result(s) in Beilstein Journal of Organic Chemistry.
Photoswitches beyond azobenzene: a beginner’s guide
- Michela Marcon,
- Christoph Haag and
- Burkhard König
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
- absence of light. Apart from some special cases where more competing mechanisms are operating [5], the thermal isomerisation typically is a first-order decay: Where I is the monitored signal at the time t, I0 the initial signal, and k the kinetic constant. Once k is known, the thermal half-life t1/2 can
- led to a strong decrease in the thermal half-life, suggesting water is also involved in the Z–E thermal isomerisation process [70]. Bridged indigos have also been reported for which the Z-isomers are unstable. By bridging the two nitrogen atoms, these compounds show planar chirality and can be
- solvents, causing a slower thermal isomerisation. The photoswitch is suitable for aqueous buffers and biological environments and is resistant to glutathione oxidase [90]. Phenyliminoindolinone 73 was designed to improve the features of iminothioindoxyl [63]. Substitution at the indole nitrogen of
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo
- Alexander Sailer,
- Franziska Ermer,
- Yvonne Kraus,
- Rebekkah Bingham,
- Ferdinand H. Lutter,
- Julia Ahlfeld and
- Oliver Thorn-Seshold
Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14
- , and high-yielding synthesis of HITub-4. Chemical structures of HITubs. Key variations with respect to HITub-4 are highlighted in dashed boxes. Photocharacterisation of HITub-4. a) Photochemical and thermal isomerisation. b) UV–vis spectra after saturating illumination at λ = 450, 505, and 530 nm
Graphical Abstract
Figure 1: a) The potent tubulin inhibitor colchicine as a lead scaffold led to the development of the HOTub g...
Figure 2: Chemical structures of HITubs. Key variations with respect to HITub-4 are highlighted in dashed box...
Figure 3: Photocharacterisation of HITub-4. a) Photochemical and thermal isomerisation. b) UV–vis spectra aft...
Figure 4: a) Resazurin reduction assay for HITub-4 and nocodazole in HeLa cells (n = 3), demonstrating the di...
Figure 5: Confocal microscopy images of immunofluorescently labelled MT networks after treatment with HITubs ...
Figure 6: Cell cycle analysis of HITub-4-treated cells. a) and b) (Z)-HITub-4 caused significant G2/M arrest ...
Recent advances towards azobenzene-based light-driven real-time information-transmitting materials
- Jaume García-Amorós and
- Dolores Velasco
Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113
- azophenols; thermal isomerisation; Introduction Nowadays, there is an ever growing interest in molecular switching materials because of the very rapid development of modern technology. This tendency arises from the great applicability of such systems as active data elaboration, storage and communication
- directly related with the thermal isomerisation rate of the photo-sensitive azo-dye in the dark, that is, with the relaxation time of the cis isomer of the azo-moiety. Slow thermally back-isomerising azoderivatives are valuable photoactive basic materials for information storage (memory) purposes. A
- photomagnetic actuating purposes [38]. In this review, we present the efforts made in our research group over the past few years regarding the molecular design of new photosensitive azoderivatives endowed with very fast cis-to-trans thermal isomerisation processes, with the main aim of transmitting optical
Graphical Abstract
Figure 1: Some important families of photochromic compounds and their photochromic reactions.
Figure 2: Photochromism of azobenzene derivatives and energetic profile for the switching process.
Figure 3: General overview of the different types of azoderivatives presented in this review.
Figure 4: Changes in the electronic spectrum of a 3 cis-to-trans isomerising ethanol solution at 45 °C (Δt = ...
Figure 5: Chemical structure and thermal relaxation time in ethanol at 298 K, τ, for the slow thermally-isome...
Figure 6: Rotation and inversion mechanisms proposed for the thermal cis-to-trans isomerisation processes of ...
Figure 7: Effect of the presence of the electron-withdrawing cyano and nitro groups on the thermal relaxation...
Figure 8: Transient absorption generated by UV irradiation (λ = 355 nm) for azo-dyes 8 (right) and 9 (left) i...
Figure 9: Effect of the presence of a positively charged nitrogen as an electron-withdrawing group on the the...
Figure 10: Mechanism proposed for the thermal cis-to-trans isomerisation process for the push–pull azopyridini...
Figure 11: Comparison between the thermal relaxation time at 298 K, τ, for the azoderivative 4 (type-I) and th...
Figure 12: Solvent effect on the thermal relaxation time at 298 K, τ, for the type-II azophenols 11–13.
Figure 13: Transient generated by irradiation with UV-light (λ = 355 nm) for the type-II azophenol 12 in ethan...
Figure 14: Proposed isomerisation mechanisms for the thermal cis-to-trans isomerisation of the alkoxy-substitu...
Figure 15: Solvent effect on the thermal relaxation time at 298 K, τ, for the type-II ortho-substituted azophe...
Figure 16: Cooperative effect of the para- and ortho-hydroxyl groups in azophenol 17.
Figure 17: Effect of the poly-hydroxylation of the azobenzene core on the thermal relaxation time at 298 K, τ,...
Figure 18: Transients generated by irradiation with UV-light (λ = 355 nm) for the poly-substituted azophenol 18...
Figure 19: Effect of the introduction of electron-withdrawing groups in the position 4’ of the azophenol struc...
Figure 20: Transient absorptions generated by UV irradiation (λ = 355 nm) of azo-dyes 11 (type-II), 19 (type-I...
Figure 21: Effect of the introduction of the hydroxyl group in the position 2’ of the push–pull azo-dye on the...
Figure 22: Effect of the substitution of a benzene ring by a pyridine one on the thermal relaxation time in et...
Figure 23: Influence of the introduction of additional electron-withdrawing nitro groups in the pyridine ring ...
Figure 24: Chemical structure and thermal relaxation time in ethanol at 298 K, τ, for the type-III azoderivati...
Figure 25: Oscillation of the optical density of an ethanol solution of azo-dye 26 generated by UV-light irrad...
