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Search for "photoisomerization" in Full Text gives 62 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction
Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36
- -substituted diazocines were prepared via Stille, Suzuki, and Buchwald–Hartwig reactions. X-ray structures are presented for derivatives 1, 2 and 7. Keywords: cross-coupling; diazocine; N-acetyl diazocine; photoisomerization; photoswitch; thermal relaxation; Introduction Diazocines are frequently used
- water at pH 7.4 and 48% at pH 9 while showing a PSS of 77% in acetonitrile for the Z to E photoisomerization. This is due to a higher overlap of the n–π*-transitions in both isomers in aqueous media. For the amino-substituted diazocine 21 the PSS (ΓZ→E) shows a slightly lower value of 37% E in water at
- pH 7.4 compared to 41% in acetonitrile, while in acidic aqueous media a PSS of 62% E for the Z→E photoisomerization was observed. This is due to the complete protonation of the amino group converting it to an electron-deficient substituent. The thermal half-lives of 13 and 21 increase by a factor of
Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy
Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254
- -bromonorbornadiene and the corresponding arylacetylenes. The norbornadienes showed absorption maxima in the range of 310–345 nm and long-wavelength zero onsets of up to 420 nm. The photoisomerization quantum yields were as high as 59% per photoisomerization event and the resulting quadricyclanes showed half-lives of
- sunlight. Furthermore, the photoisomerization quantum yield is very low and therefore not suitable for an application [7][8][14]. One promising way to overcome these disadvantages is the introduction of a donor–acceptor system at the norbornadiene double bonds, which has resulted in the development of new
- ]. Accordingly, a slightly more pronounced red shift (20 nm) has been reported for derivatives 1d and 1f which carry an additional electron-acceptor in the 3-position of the norbornadiene unit [33][34]. The photoisomerization of the norbornadiene derivatives 1h–l,n (Scheme 3) was investigated photometrically in
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
- )rotaxane framework The rotaxane framework is often deployed as a molecular device in which the positional relationship between the axle and wheel is controlled by external stimuli [14][32]. Acid–base, photoisomerization, redox, ion recognition, solvent polarity, or heating treatment is generally used for
- is derived from the hydrophobic-interaction-based inclusion formation; thus they are only low number of reports on their structural control. The photoisomerization-based structural control system is often applied to CD-based rotaxane. Typically, the photo-switch behavior is used, and it is based on
- 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
1,2-Difluoroethylene (HFO-1132): synthesis and chemistry
Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171
- ]. Along with this, photoisomerization is described in patent literature [71][72][73][74]. It was shown that the experimentally observed enthalpy of isomerization (0.928 kcal/mol [47]) is in agreement with the calculated difference in the total energy of the two isomers (0.959 kcal/mol [65][75]). Cis-1,2
A fiber-optic spectroscopic setup for isomerization quantum yield determination
Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150
- textbook example status, the photoisomerization of azobenzene is still under active investigation. Over the past two decades, both experimental [23][26] and theoretical work [27][28][29][30][31][32] has been performed to explain the differences in quantum yield. Not only the exact details of the
- photoisomerization are still under debate, but also the absorption spectrum of cis-azobenzene has been redetermined as recently as 2017 [17]. With the re-evaluated values for the molar absorptivities, the Φ of azobenzene were recalculated by the same group immediately afterwards [24]. As shown by Vetráková et al
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
- (Figure 1a). Upon 625 nm red-light irradiation for 60 s at 20 °C to reach the photostationary state (PSS), the strong absorption band at 470–685 nm was diminished, with a clear isosbestic point at 259 nm (Figure 1a, red line), which indicates a selective photoisomerization process from the open-isomer O
- reversibility and photostability in organic solvent (Figure S1a and S1b, Supporting Information File 1). The photoisomerization between O-DA11 and C-DA11, upon irradiation with 625 nm red light and thermal back reaction in the dark, could be repeated for over five cycles, with only 5% absorbance decreases per
- 1d and Figure 1f, blue line), the strong absorption band had recovered and indicated a selective photoisomerization process from the open-isomers O-DA7 and O-DA6 (Figure 1c–f, black and blue lines) to the cyclized-isomers C-DA7 and C-DA6 (Figure 1d and Figure 1f, red line). The results showed
Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA
Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132
- reversible light modulation of their activity since each isomer shows distinct structural and electronic properties [13]. Photoisomerization-induced conformational and polarity changes may allow to increase or decrease the interaction with the target protein or receptors, then modulate the drug potency on
- /off or from low to high. This strategy can be used for specific targeting or local drug activation to reduce its toxicity [14]. There is an increasing use of the photoisomerization to control the conformation as well as the activities of various biomolecules with the development of photopharmacology
- factor up to 1.6 has been observed for the divalent ligand [23]; while almost no difference of inhibition was observed for LecA and LecB upon irradiation, probably due to the low photoisomerization of glycodendrimers [24]. Very recently, the group of Wittmann reported an arylazopyrazole-linked divalent N
Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis
Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106
- Supporting Information File 72: General information, detailed experimental procedures, additional spectroscopic data, quantum-mechanical calculations, photostability and photoisomerization experiments. Funding We acknowledge generous financial support from the JGU Mainz and the German Federal Environmental
Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries
Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93
- [10]. These properties include the large storage energy, high gravimetric energy storage density, large barrier for thermal back isomerization reaction, photoabsorption in the visible range, high quantum yield of photoisomerization, and so forth [10]. Photoswitches like dihydroazulene
Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group
Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47
- resulting O-acylated isomers 3a–c were nonemissive. According to previous findings, the 2a–c→3a–c transformation is a two-step process: 1) Z–E photoisomerization and 2) extremely fast nonadiabatic N→O acyl group transfer (Scheme 2) [14][16]. These two stages occur almost simultaneously, and hence the term
- photoisomerization of the C=C bond, followed by very fast thermal N→O migration of the acyl group and the formation of O-acylated isomers. This rearrangement was accompanied by a decrease of the initial fluorescence intensity at 465–468 nm up to zero, since the resulting OAc− form was nonemissive. The reverse
- alternate addition of Fe2+ and AcO−. Synthesis of compound 1 and N-acylated compounds 2a–c. Photoisomerization of N-acylated ketoenamines 2a–c. Sequential interaction of compounds 2a–c with Fe2+ and AcO−. Absorption and fluorescence spectra of compounds 1, 2a and 2b in acetonitrile and compound 2c in DMSO
Switchable molecular tweezers: design and applications
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
Photochromic derivatives of indigo: historical overview of development, challenges and applications
Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23
- 1956: first report on the photochromism of N,N'-dimethylindigo 1956–1978: extension of the range of photochromic N,N'-dialkyl and N,N'-diacetylindigos and development of experimental and theoretical approaches towards the characterisation of the photoisomerization of indigo 1979–1984: development of
- –E isomerization of N,N'-substituted indigos Since 1980s: detailed mechanistic and structural studies of the photoisomerization of indigo 2015: first report on photochromism of N,N'-diBOC indigos (follow-up studies in 2019, 2021) 2017: rationalisation of the design of indigo photochromes: symmetrical
- , indigo exists in a planar E-form, which is more stable than the overcrowded and non-planar Z-form (Figure 6a) [23]. Irradiation of E-indigo, however, does not result in the photoisomerization into the Z-form due to the rapid proton transfer occurring in the excited state (ESPT) from the N atom towards
Photoredox catalysis harvesting multiple photon or electrochemical energies
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
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
Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions
Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41
- the borylation reaction (see above). Photochromism of naphthylnorbornadiene 6b The photoisomerization reaction of substrate 5b was monitored by absorption spectroscopy (Figure 1) and by 1H NMR-spectroscopic analysis (see Supporting Information File 1, Figure S51). In MeCN solution, norbornadiene 5b
- photoisomerization of 2-(1-naphthyl)norbornadiene (5b) in MeCN, c = 20 µM, T = 20 °C, λex = 315 nm. The arrows indicate the development of the absorption bands with reaction time. Inset: Thermally induced back conversion of quadricyclane 6b into norbornadiene 5b at 60 °C as monitored by the increase of the
Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies
Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17
- photodimerization [55][56][57], photocleavage [58][59], and cis–trans photoisomerization [60][61][62][63][64][65]. While it had been well-established to access oligomer formation and gelation, a light-switchable particle size has remained a challenge until realized through the mentioned electrostatic self-assembly
Insight into functionalized-macrocycles-guided supramolecular photocatalysis
Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15
- photochemical reactions, including photoisomerization, photocyclodimerization, and H2 evolution [7][23]. Chirality induction in a prochiral guest via photochemical reactions is a delightful approach. This can not only transfer the chirality of the host cavity to the molecular photoproduct via excited-state
- supramolecular chiral interactions but can also improve the photoenantiodifferentiating proficiency of the host. To prove this concept, Inoue et al. investigated the photoisomerization of (Z)-cyclooctene ((Z)-6) to the chiral E-isomer (E)-6 in an aqueous methanol solution through host–guest interactions between
- . Cibulka et al., Catalytic Photooxidation of 4‐Methoxybenzyl Alcohol with a Flavin–Zinc(II)‐Cyclen Complex, Chemistry – A European Journal, John Wiley and Sons. Enantiodifferentiating Z–E photoisomerization of cyclooctene sensitized by a chiral sensitizer as the host. Adapted with permission from [24
Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity
Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216
- dual mechanism-of-action treatment for Alzheimer’s disease [4][10][11][12][13]. However, piperine (1) has some limitations as a drug lead. For example, it has poor solubility, and it is susceptible to photoisomerization of the conjugated system [15][16][17]. This prompted us to consider whether there
Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches
Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210
- . Photoisomerization of the azo unit between cis and trans is achieved upon irradiation with 505 nm (trans→cis) and 435 nm (cis→trans). Concurrently with the isomerization and coordination/decoordination, the spin state of the Ni ion switches between singlet (low-spin) and triplet (high-spin). Previous studies have
Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores
Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190
- primarily engaged in synthesizing various types of such multichromophoric systems to compare their photochemistry in detail [9][10][11][12][13][14][15]. Since in acyclic enones like C, E/Z-photoisomerization becomes one of the major energy dissipation pathways, we selected rigid bicyclic multichromophoric
- in acetonitrile at rt. Quantitative photoisomerization of 1 to 2 in all types of solvents. Accepted mechanistic pathway for the photochemical transformations of 1. Photochemical reactions of 3a–g. Irradiation using a Hanovia medium pressure 450 W lamp with a pyrex filter; a) conditions and yields are
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
- -epoxypropane to propylene carbonate using an aluminum porphyrin and a photoresponsive ligand. The catalytic activity of the metal porphyrin depended on the axial coordination of an azostilbene and coordination of the latter ligand was controlled by photoisomerization of the stilbene unit [9]. Hecht et al
Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides
Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149
- obtained in earlier studies [5][6][14][15][16]. Moreover, the occurrence of the Z/E-photoisomerization concomitant of the first stage of the rearrangement can be traced at small irradiation times (less than 1–2 min) of fulgide 3Z in acetonitrile solution with light of 436 nm. As shown in Figure 4 a slight
- ) (2.5 × 10−5 M, T = 293 K). Electronic absorption spectra of fulgimide 8E in acetonitrile solution before (1) and after irradiation with light of 365 nm for 10 (2), 20 (3), 30 (4), 60 (5), 90 (6), 120 (7), 180 (8), 260 (9) and 320 s (10) (2.5 × 10−5 M, T = 293 K). Photoisomerization of 2-benzo[b]thienyl
A simple and easy to perform synthetic route to functionalized thienyl bicyclo[3.2.1]octadienes
Beilstein J. Org. Chem. 2020, 16, 1092–1099, doi:10.3762/bjoc.16.96
- . Further, the separated isomers of 3–7 were irradiated and the reaction course followed by UV spectroscopy. In all cases, the longest wavelength absorption band gradually disappeared upon irradiation. Based on previous research, it was assumed, that the preliminary process could be a photoisomerization
Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides
Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8
- -33501 Bielefeld, Germany Organic Chemistry II, Department Chemistry – Biology, Siegen University, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany 10.3762/bjoc.16.8 Abstract Azobenzenes are photoswitchable molecules capable of generating significant structural changes upon E-to-Z photoisomerization in
- peptides or small molecules, thereby controlling geometry and functionality. E-to-Z photoisomerization usually is achieved upon irradiation at 350 nm (π–π* transition), while the Z-to-E isomerization proceeds photochemically upon irradiation at >400 nm (n–π* transition) or thermally. Photoswitchable
- )phenyl)azophenylacetic acid, as the linker between two Im/Py polyamide strands. Only the (Z)-azobenzene-containing polyamides bound to the minor groove of double-stranded DNA hairpins. Photoisomerization was exemplarily evaluated by 1H NMR experiments, while minor groove binding of the (Z)-azobenzene
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