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Search for "azobenzene" in Full Text gives 99 result(s) in Beilstein Journal of Organic Chemistry.
Substituent effects in N-acetylated phenylazopyrazole photoswitches
Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66
- examples. Azobenzene and its derivatives show two characteristic absorption bands, namely a π→π* transition around 330 nm and an n→π* one around 450 nm, respectively [22]. The molecule can populate the thermodynamically metastable Z isomer by addressing these transitions in the thermally stable E form. The
- relative position of the absorption bands in the azobenzene derivatives depends on the substitution pattern on the aromatic rings, which can act as a handle to affect the absorption properties of the compound class [3]. For instance, push–pull systems or the introduction of tetra-ortho substituents were
- reported to either bathochromically shift the UV–vis absorption spectrum or lead to a better separation of the n→π* bands of the two photoisomers and allow for visible-light-responsive switches [23][24][25][26]. In recent years, heteroaryl azobenzene derivatives have revealed superior properties to
Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion
Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57
- space and additionally, secondary interactions exerted by multivalent glycoligands have an effect on affinity. A recently introduced orthogonally photoswitchable heterobivalent azobenzene Glc/Man glycocluster was utilized to examine these aspects of carbohydrate recognition in a bacterial adhesion
- glycophotoswitches in their different isomeric states led to new insights into the role of ligand orientation in carbohydrate recognition. The experimental results were underpinned by molecular modeling. Keywords: azobenzene glycoconjugates; carbohydrate recognition; docking; FimH; orthogonal photoswitching
- ]. Specifically, the reversible E/Z isomerization of the azo group in azobenzene glycosides is suited to control the spatial presentation of glycoligands and, for example, switch carbohydrate-specific bacterial adhesion on and off [20][21][22][23]. Indeed, glycoazobenzene derivatives are excellent tools to
Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction
Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36
- azobenzene is that the switching efficiency decreases sharply with increasing water content in the solvent. In a recently published paper, we reported that replacing one CH2 group in the bridge with NCOCH3 not only confers intrinsic water solubility, but also largely eliminates the problem of reduced
- spectra [1]. Moreover, the ethylene bridge creates a cyclic 8-membered core, inverting the thermodynamically stability in favor of the Z boat conformation compared to parent azobenzene, which has a stable E configuration [1][2][3][4]. Preceding studies including azobenzene-based photopharmacophores showed
- that, in most cases, the sterically demanding Z configuration is biologically inactive, while the stretched E configuration is biologically active [5][6][7]. Because of the inverted thermodynamic stability compared to azobenzene, the stable Z configuration of the diazocine can be administered and
Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures
Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252
- the relationship between the photoisomerization of azobenzene or stilbene and CD to form the inclusion complex structure. In 1997, [2]rotaxane exhibiting an azobenzene moiety in its axle component was synthesized, and its structural control was achieved via the photoisomerization of the azobenzene
- (Figure 5A) [56]. In the structure, α-CD was located on the trans-azobenzene moiety before ultraviolet (UV) irradiation, after which it moved to the methylene moiety based on the cis-isomerization of the azobenzene by UV irradiation. After the azobenzene moiety was moved back to the trans-isomer via
- visible-light irradiation or heating, CD was moved back to the azobenzene moiety, and the entire process was reversible. This system was further developed in 2005 by introducing bipyridinium moieties to implement the selective transfer of the wheel via heating or light irradiation (Figure 5B) [57]. During
Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies
Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176
- azobenzene (Azo) or, more recently, arylazopyrazoles (AAPs), which change shape and polarity on photoisomerisation between the E and Z states, thus changing the self-assembled structure. Small-angle X-ray scattering (SAXS) is a powerful technique to probe the morphology of PS and can be used to measure the
- guidelines for future X-ray experiments using photoswitchable molecules, which can aid more accurate understanding of these materials for application in solar energy storage, catalysis or controlled drug delivery. Keywords: arylazopyrazole; azobenzene; micelle; photoswitch; X-ray; Introduction The design
- molecules to create photosurfactants (PS), whose molecular shape and polarity can be modified using light [4][5][6]. Of the PS studied, most use an azobenzene (Azo) photoswitch that undergoes trans-to-cis (E-to-Z) isomerization on irradiation with UV light, typically forming a photostationary state (PSS
A fiber-optic spectroscopic setup for isomerization quantum yield determination
Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150
- be obtained from the UV–vis absorption spectra. We show that our results for the prototypical photoswitch azobenzene are in excellent agreement with the literature. The analysis of the errors showed that the quantum yields determined using this method are in the same order of magnitude as when using
- ]. Among the different switches known in the literature, azobenzene is a textbook example of a photoswitch operating via a double bond isomerization mechanism, with the first reports of its trans-to-cis interconversion under direct sunlight dating back to the work of Hartley in 1937 [2]. Over the decades
- , azobenzene and its derivatives [3][4] have found numerous applications in the development of novel materials [5][6], photopharmacology [7][8][9] but also as actinometers [10][11], due to the large geometry changes upon isomerization [12] and easily accessible derivatives [1][7][13][14]. The absorption
Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds
Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142
- , stiff-stilbene [26], azobenzene [27][28], molecular motors [19][29][30], spiropyran [31][32][33], indigo [34][35], and donor–acceptor Stenhouse adducts (DASAs) [36][37], have been used in supramolecular systems for photoswitchable smart electronic, optoelectronic, and biomedical materials [30][38][39
Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA
Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132
- possess excellent photophysical properties and strong affinity for targeted LecA with Kd values in the micromolar range. Analysis of the thermodynamic contribution indicates that the Z-azobenzene isomers have a systematically stronger favorable enthalpy contribution than the corresponding E-isomers, but
- [11][12][13][14][15][16][17][18]. The group of Lindhorst has reported a series of mannosyl azobenzenes targeting E. coli lectin FimH, demonstrating the possibility to control the type 1 fimbriae-mediated bacterial adhesion to a self-assembled monolayer of mannosyl azobenzene on a gold surface [19][20
- ] or to mannosyl azobenzene-modified human cells [21] through photoswitching the orientation of the attached mannoside [22]. Photoswitchable glycooligomers [23] or glycodendrimers [24] have been investigated for the inhibition of PA lectin PA-IL or LecA and LecB. A variation of the IC50 value by a
Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations
Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119
- , the addition of the benzoyl radical to azobenzene results in the generation of a nitrogen-centered radical. This radical is then subjected to reduction by the reduced photocatalyst, producing the nitrogen-centered anion intermediate. Ultimately, the protonation of this anion gives rise to the desired
Switchable molecular tweezers: design and applications
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
Light-responsive rotaxane-based materials: inducing motion in the solid state
Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64
- azobenzene and ferrocene motifs (Figure 1a). The azobenzene scaffolds play a dual role, both as the engine transforming photoenergy into mechanical motion via trans/cis photoisomerization upon UV light input and as a modulator of the crystalline packing by varying the para-substituent R1, which leads to
- , respectively, and a methyl group at the para-position of the ended-aromatic ring of the azobenzene motif (R1), experienced an upward bending using a 360 nm diode pump solid state laser irradiation source. By irradiating crystals of 1a at 445 nm using a power of 4 mW, a reversible curling motion was observed
Dissecting Mechanochemistry III
Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150
- were also key reagents to develop the mechanochemical halogenation of azobenzenes as studied by Ćurić and co-workers [4]. They demonstrated how, depending on the azobenzene structure, the halogenation of the C–H bonds with NBX occurred in the presence of Pd(II) catalysts or under metal-free conditions
Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives
Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121
- bioactivity [54][55]. To increase the yield of the alkene complexes, the addition of an external “H-abstractor” may be helpful, to suppress disproportionation. A possible candidate may be a reduced radical form of azobenzene. Indeed, the preparative electrolysis performed in the presence of the equimolar
- Ph2N2 additive changed the relative ratio of alkene to hydrogenated derivatives in favor of the former one (see Table 1). As follows from Table 1, the azobenzene additive allows increasing the yield of the alkene complexes up to 85% suppressing formation of the hydrogenated complexes. Spectral NMR
- due to the bioactivity of such compounds [56][57]; thus, elaboration of new synthetic protocols to these multifunctional molecules is a topical problem. Complex 4 was subjected to reductive ring opening at a potential of −1.5 V (Ag/AgCl, KCl(sat.)) in the presence of an equimolar amount of azobenzene
Continuous flow synthesis of azobenzenes via Baeyer–Mills reaction
Beilstein J. Org. Chem. 2022, 18, 781–787, doi:10.3762/bjoc.18.78
- Azobenzene, as one of the most prominent molecular switches, is featured in many applications ranging from photopharmacology to information or energy storage. In order to easily and reproducibly synthesize non-symmetric substituted azobenzenes in an efficient way, especially on a large scale, the commonly
- used Baeyer–Mills coupling reaction was adopted to a continuous flow setup. The versatility was demonstrated with a scope of 20 substances and the scalability of this method exemplified by the synthesis of >70 g of an azobenzene derivative applied in molecular solar thermal storage (MOST) systems
- was also tested for a large number of other azobenzene derivatives to determine the scope of the method (Table 1). All aniline derivatives 2a–s were commercially available and the corresponding azobenzenes 1a–s were synthesized according to the general procedure in continuous flow as described before
Mechanochemical halogenation of unsymmetrically substituted azobenzenes
Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69
- using N-halosuccinimides as the halogen source under neat grinding or liquid-assisted grinding conditions in a ball mill has been described. Depending on the azobenzene substrate used, halogenation of the C–H bonds occurs in the absence or only in the presence of PdII catalysts. Insight into the
- reaction dynamics and characterization of the products was achieved by in situ Raman and ex situ NMR spectroscopy and PXRD analysis. A strong influence of the different 4,4’-substituents of azobenzene on the halogenation time and mechanism was found. Keywords: azo compounds; halogenation; mechanochemistry
- solvent-free synthesis of phenanthridinones via a cascaded oxidative C–N coupling followed by a halogenation reaction [50]. Only recently, our group carried out a detailed synthetic and mechanistic study of the mechanochemical PdII-catalyzed bromination of unsubstituted azobenzene (L1) by N
Synthesis of a new water-soluble hexacarboxylated tribenzotriquinacene derivative and its competitive host–guest interaction for drug delivery
Beilstein J. Org. Chem. 2022, 18, 539–548, doi:10.3762/bjoc.18.56
- derivatives in organic media have been well established [22][23][24][25][26][27]. Recently, the host–guest chemistry of TBTQ derivatives in aqueous phase was also investigated by us [28][29]. In particular, a water-soluble TBTQ-based hexacarboxylate (TBTQ-C6) was prepared and bound with an azobenzene
Peptide stapling by late-stage Suzuki–Miyaura cross-coupling
Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1
- -switchable azobenzene staple [33][34]. Moreover, it has been shown that Pd-mediated cross-couplings can be successfully employed in the generation of cyclic and conformationally stabilised peptides. The groups of Buchwald, Pentelute, and Ackermann pioneered the development of Pd-mediated arylation chemistry
Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds
Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185
- -workers showed that azo groups enable the organocatalytic asymmetric arylation of indoles. The nucleophilic aromatic substitution between the azobenzene derivative 24 and indoles 25 was carried out in the presence of 2.5 mol % chiral phosphoric acid (CPA 8, Scheme 9a), leading to the intermediate I-4
- type of axially chiral indoles 27 (Scheme 10) bearing aniline groups by direct arylation and rearrangement in moderate to good yields with excellent enantioselectivities of mostly 99% ee (Scheme 9b) [59]. The electronic properties and position of the substituents on the azobenzene ring did not affect
Constrained thermoresponsive polymers – new insights into fundamentals and applications
Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138
- cyclic ketene acetals [277]. This copolymer also showed a well-controllable reversible UCST behavior in aqueous solutions. In 2020, Zhao et al. reported that by incorporating azobenzene functionalities into polyacrylamide copolymers, the responsive UCST behavior was furthermore tuneable via light
Substituted nitrogen-bridged diazocines
Beilstein J. Org. Chem. 2021, 17, 1503–1508, doi:10.3762/bjoc.17.107
- makes them promising candidates for applications in photopharmacology. The halogen substituents allow further functionalization via cross-coupling reactions. Keywords: bridged azobenzene; diazocine; photopharmacology; photoswitch; triazocine; visible light switch; water-soluble switch; Introduction
- azobenzene-based photopharmacophores, the bent Z configuration is biologically inactive [10][11][12]. Hence, (and in contrast to azobenzenes) the thermodynamically stable and biologically inactive Z-isomer can be administered and switched on with light at the site of interest with spatiotemporal resolution
Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding
Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13
- weakens the halogen bond. In a first step, we calculated the interaction energies of the assemblies of the azobenzene halogen bond donors F4St, F4Az, F3Az, F2Az or F2’Az with NO2-C1. For computational efficiency reasons the terminal alkoxy chains were substituted by methoxy groups. The interaction
- induces the formation of nematic mesophases with broad temperature ranges, the temperature range of the mesophase of the azobenzene-based assemblies is significant narrower. Theoretical calculations and the modular use of halogen bond donors with changing fluorination degree reveal that at least three
Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes
Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209
- made towards switchable macrocyclic receptors, in which crown ethers are functionalized with a stimuli-responsive unit [14][15]. These studies were mainly motivated by a biomimetic approach and included examples such as crown ethers incorporating photo-responsive azobenzene [15][16] or redox-active
Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst
Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179
- . reported on the photoswitching of the basicity of a piperidine nitrogen by reversible steric shielding of the nitrogen lone pair. The photoswitchable base was applied as a nucleophilic catalyst in the nitroaldol (Henry) reaction. Attached to a sterically demanding azobenzene unit, the lone pair was
Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo
Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14
- native cytoskeleton function. We and others have reported on photoswitchable azobenzene-based inhibitors of tubulin polymerisation [10][11][12][13] that have since been used in studies of neuronal trafficking [14] and embryonic development [15][16], and we have recently reported biologically robust
- heterostilbenes that deliver green fluorescent protein (GFP)-orthogonal MT photocontrol [17]. However, in both azobenzene and heterostilbene scaffolds, the steric properties of the E- and Z-isomer are so different that the protein binding site shape determines that the Z-isomer (the lit-form) is the more
- straightforward attachment of photoswitches on the pharmacophore periphery. We expected that embedding (which is referred to as azologization in the case of azobenzene-based photopharmaceuticals [19]) should in general lead to more significant alterations of the binding-relevant structure, and increase the
Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion
Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13
- attempts have also been made to develop photochromic DNA binders. Thus, it has been shown with spiropyran [19][20][21], stilbene [22][23], azobenzene [24][25][26][27][28], dithienylethene [29][30][31][32], chromene [33], and spirooxazine [34] derivatives that specifically modified photochromic ligands bind
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