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Search for "photoproducts" in Full Text gives 42 result(s) in Beilstein Journal of Organic Chemistry.
Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene
Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39
- photoproducts were insoluble resulting in decreased concentration of 9,10-ANTH(BnF)2 in the irradiated solution or new photoproducts had similar absorption features. To identify the photoproducts in the irradiated solutions of ANTH and 9,10-ANTH(BnF)2, complementary NMR analyses were carried out (Figures S6 and
- (C8F17)2 [36]. These results make it clear that monitoring photoirradiated solutions by UV–vis spectroscopy must be accompanied by complementary analyses to enable accurate interpretation of the changes in the UV–vis spectra and identification of the photoproducts. The next comparative photostability
- greater than the parent ANTH molecule. Significantly, no new 1H NMR resonances appeared upon irradiation of the 9,10-ANTH(BnF)2 solution, except for proton signals due to 9,10-ANTH(BnF)2, indicating that no new soluble photoproducts are formed in the absence of oxygen. On the other hand, during
Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye
Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37
- Figure 2b. We hypothesized that this reaction occurred in the solid state, and further investigations confirmed this. To validate our findings, we employed single-crystal X-ray diffraction, which revealed the packing mode in the crystal and identified any photoproducts formed. Two additional compounds
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
- up to 8 h at room temperature. Furthermore, the norbornadienes were transformed quantitatively into their quadricyclane photoproducts by irradiation with green light (520 nm) in the presence of a photosensitizer. Keywords: light energy conversion; photochemistry; photochromism; quadricyclanes
- , such as absorption in the range of the solar spectrum, a high quantum yield of the photoreaction, long half-lives of the photoproducts, and a high energy storage density [7][8][12][13][14]. In this context, several different MOST systems have been explored, including, for example, anthracenes [15
- ). Indeed, the quenching efficiency of triplet-excited [Ru(phen)3](PF6)2 by 1i was calculated to be as low as 5% under the highly diluted conditions required for the experiments in Figure 3. In order to gain structural information about the photoproducts, the photoisomerization reactions were also examined
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
- shows signals that we assigned to the triplet spectrum of Aza-H in Figure 1B. Although the singlet-excited photocatalyst is quenched by TsNa, indicated by the reduced triplet formation of Aza-H, our conclusion is that this quenching is unproductive as no new photoproducts are observed. Interestingly, in
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
- Figure 1a, the previously studied BBD-based photoswitches (NBD/QC and BOD/TCO) generate photoisomers with two strained 3-membered rings. In contrast, the photoinduced chemical transformation of all studied bicyclic dienes yield photoproducts containing one 4-membered and one 3-membered ring. Therefore
- unsubstituted NBD/QC (124.10 kJ/mol) and BOD/TCO (118.10 kJ/mol) couples [33]. This is indeed expected due to the formation of comparatively stable and large rings in the metastable photoproducts. Among all the studied BBD switches, the barrier height for back isomerization of the photoproduct to the diene is
- , forecasting the photophysical properties of BBD switches is one of the prominent objectives of the present investigation. The optical spectra of the dienes and photoproducts of both the types of BBD switches are depicted in Figure 4. The optical spectra were obtained as the outcome of the first fifteen
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
- photoproducts 3a–c under the influence of irradiation was developed. We applied a modified procedure using a Sweko IP65 LED emitter that had been previously developed in our studies for similar tasks [30]. For this purpose, a suspension of a yellow solid 2a–c in acetonitrile was boiled for 10–15 s and then
- reaction occurred catalytically in the presence of HClO4. A special technique for the preparative synthesis of photoproducts was developed. For the first time in the course of studying N→O acylotropic migrations, O-acylated photoproducts were comprehensively characterized by IR, 1H and 13C NMR spectroscopy
Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions
Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11
- not be determined because it was not available in pure form on preparative scale. With the absorption data, specifically the molar extinction coefficients, obtained from the isolated benzo[c]quinolizinium derivatives, the yields of the initially formed photoproducts 3c, 3e, 3f, and 3g in the reaction
- mixtures were determined to be 78%, 73%, 30%, and 20% in MeCN, >97%, 80%, 44% and 55% in H2O, and 32%, 76%, 53% and 38% in Na phosphate buffer. Overall, the initially formed amounts of photoproducts are significantly larger than the ones of the isolated compounds, in the case of 3c and 3e even with good
Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment
Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58
- of the photoproducts (Table 2). Based on the structure of compound 11a we assumed that it could be converted into a polyaromatic product using conventional synthetic methods. However, the use of different systems (TsOH/toluene, HCl/EtOH, DBU/EtOH, MeONa/MeOH) resulted only in the decomposition of the
- -bottomed glass flask. Synthesis of photoproducts 12. Reaction conditions: method A) 10 (0.5 mmol), DMF (15 mL) irradiation for 48 h; method B) 1) 9 (0.5 mmol), DMF (15 mL), irradiation for 96 h; 2) CDI (1.75 mmol, 0.28 g), MeCN (5 mL), reflux, 2 h. Optimization of the condensation conditions.a Ratio of
- photoproducts 11 and 12.a Supporting Information Supporting Information File 42: Experimental procedures, characterization data of all products, copies of 1H, 13C NMR, HRMS spectra of all new compounds, and X-ray crystallographic data.
Insight into functionalized-macrocycles-guided supramolecular photocatalysis
Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15
- complexes (1:1, 2:1, 1:2, and 2:2). For the 1:1, 2:1, and 1:2 host–guest complexes, the thermodynamic association (Ka) and dissociation constants (Kd) for the reactive guests and photoproducts are crucial for the fundamental understanding of supramolecular noncovalent interactions [12][13]. In addition
- , during the catalytic process, the reactive guest should have a greater binding affinity or the photoproducts should have the lowest binding affinity with the supramolecular host to avoid product inhibition, so as to produce a better catalytic turnover efficiency [14][15]. However, it is quite complicated
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
- distribution of these photoproducts may be wavelength dependent [7]. In order to investigate the photoreaction of such enones, we observed a complete 1,2-acyl shift (1,2-AS) photoproduct formation when 1a–h have been irradiated (Scheme 1) [14][16]. We also observed that such a rearrangement took place very
- given in Table 1. Synthesis of 7a,b. Photochemical reaction of 7a,b; a) solvent and conditions are given in Table 2. Conversion of ketene 10a to its methyl esters 11a,b. Chemical yields of the formation of photoproducts 4, 5 and 6. Result of photoreaction of 7a,b at various wavelengths in different
[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin
Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110
- solutions containing 2 and AN, 3 and AN, or the corresponding complexes 2@β-CD and 3@β-CD with AN. Scheme 3 and Scheme 4 show products formed in the photochemical reactions, whereas ratio of photoproducts obtained is given in Table 2. The addition of H2O to the solution of 2 or 3 in CH3CN generally increase
- , but it did not quench the cycloaddition of 3AMY with AN. Thus, cycloadduct 11 was detected after irradiation of 3 with AN in CH3CN/H2O, but not when a base was added to the solution. Addition of β-CD did not affect the decarboxylation reaction, since the same conversion to photoproducts was observed
- CH2Cl2 (2 × 50 mL) and EtOAc (2 × 50 mL). The organic extracts were dried over anhydrous Na2SO4, and CH2Cl2 and EtOAc were combined. The solutions were filtered and the solvent was removed on a rotary evaporator. The photoproducts were separated by chromatography on semipreparative HPLC followed by
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
- [3.2.1]octadiene derivatives by irradiating the toluene solution of compound's 3–7 mixture of cis- and trans-isomers in the presence of iodine (Scheme 2 and Scheme 3). The electrocyclization reactions were successfully implemented in most cases and photoproducts 8–11 were obtained in moderate yields. The
- only exception was the cyano derivative 6 which was proven to be non-reactive, since the reaction mixture showed solely the presence of the initial cis- and trans-isomers. Figure 9 presents the 1H NMR spectra of photoproducts 8 and 9, in comparison to the spectra of the starting aldehyde 1. The effect
- the HRMS measurements is appreciated. Funding The University of Zagreb short term scientific support under the title “Synthesis and functionalization of novel (hetero)polycyclic photoproducts as cholinesterase inhibitors” is gratefully acknowledged.
Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0
Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40
- obtained photoproducts should not exhibit such a strong brownish color as observed in photochemical studies to explore the heptamethines 48 [63]. Nowadays, this arises as a big challenge to use such absorbers in applications where the color formed can be seen as an issue. Absorbers comprising indolium and
- with our findings where no formation of singlet oxygen was confirmed [89]. Other pathways request attention which could be formation of the O2-• radical to propose an alternative [90]. Such intermediates exhibit high reactivity resulting in similar photoproducts as disclosed for photoinduced electron
- photoproducts were formed and cationic photopolymerization even of epoxides succeeded with good conversions vide infra. Additional absorbers fitting in this scheme comprise at the meso-position alternative substituents such as Phenyl or Chlorine (see Table 1 for comparison). Surprisingly, this reaction has not
p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies
Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33
- latter compounds and check their photoproducts using UV spectrometry. Indeed, when they were irradiated in 1, 2, 5, 10, 15, 20, 25 and 30 min time intervals compound 12 showed the formation of an intermediate with λmax at 338 nm which gradually increased, probably indicating a one-way photochemical path
- . For the dissociation reaction of compound 12 in the triplet state, the molecule passes through a very small energy barrier and dissociates finally into its photoproducts which are the two ground state radicals indicated in Scheme 2. The almost negligible change in geometry on going from T1 min to T1
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
- )bisquinolizinium 4b and 4c as photoproducts in quantitative yield. The products 4b and 4c were fully characterized by NMR spectroscopy (1H, 13C, COSY, HSQC, HMBC, and ROESY) and mass spectrometry, which revealed a cyclobutane structure, specifically by the appearance of the characteristic NMR signals of the
Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells
Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84
- compound 2 with rapid radical recombination. Over 70% of the caged TEMPO 2a and ≈85% of 2b were recovered after 2 h of irradiation under degassed conditions. The retarded formation of TEMPO after 5 min of irradiation is due to the decrease in the relative absorbance of 2a to those of primary photoproducts
- . Photochemical generation of TEMPO radical. Synthesis of caged nitroxides 2a and 2b. Photochemical generation of TEMPO radical and photoproducts 6 and 7 under air atmosphere. Isodesmic reaction from BRa and 5b to 5a and BRb. Photophysical data for 2a, 2b, 5a, and 5b in benzene (DMSO). Supporting Information
The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones
Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275
- crystalline solids in good to excellent yields of 63–95% (Table 2, entries 1–17). In many cases, the photoproducts 3 simply precipitated during irradiation or after removal of the co-solvent acetone and could be isolated by filtration. In all other cases, the desired products 3 were obtained after extraction
The chemistry and biology of mycolactones
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems
Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115
- photoproducts 4 and 5, respectively. By contrast, under the same conditions, 3 did not give rise to any isolable Ch-derived product. These results point to an intramolecular hydrogen abstraction in 1 and 2 from the C7 position of Ch and subsequent C–C coupling of the generated biradicals. Interestingly, 2 was
- singlet oxygen, thus being able to initiate Ch oxidation from their triplet excited states following either of the two competing mechanistic pathways. Keywords: aryl ketones; hydrogen abstraction; lipid peroxidation; photoproducts; triplet excited state; Introduction Among the constituents of cell
- unambiguous stereochemical assignment, authentic samples of 1 and 2 were prepared by direct esterification of (R)- and (S)-SP with α-Ch [17]. Steady-state photolysis In order to investigate photoproducts formation, steady-state irradiation of dichloromethane solutions (ca. 10−3 M) of 1–3 was performed under
Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles
Beilstein J. Org. Chem. 2014, 10, 2222–2229, doi:10.3762/bjoc.10.230
- , which are identified and characterized by spectroscopic methods. The photoproducts formed are relatively unstable and spontaneously or on silica gel undergo oxazoline ring opening followed by formation of formiato- or formamido-benzobicyclo[3.2.1]octenone derivatives. On irradiation of 4-(2-vinylstyryl
- formation of the photoproducts 8 and 10 can be explained by intramolecular cycloaddition and formation of resonance stabilized biradicals A/A’ followed by the 1,6-ring closure (Scheme 4). An 1,3-H shift, as in furan and thiophene derivatives [6], and rearomatization to fused oxazole derivatives B/B’ is not
Photorelease of phosphates: Mild methods for protecting phosphate derivatives
Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212
- , however, the chromophore did not undergo the photo-Favorskii rearrangement, forming only the reduction product 2-acetyl-6-hydroxynaphthalene (6) in addition to other unidentified photoproducts (Scheme 5). These results paralleled our observations for 14a,b in aq MeCN. Finally, photolysis of 5,8-BQA
- intact or rearrange to more strongly absorbing chromophores which compete for the effective radiation wavelengths, often resulting in incomplete conversions that compromise their synthetic utility. These chromophores and especially their photoproducts are also highly fluorescent, which frequently prove
- are known to undergo nucleophilic substitution and not reduction to the methyl ketone products 6, 12 or 15 [38][39]. Substitution by solvent would trap the intermediate biradicaloid (or zwitterion) to form, in the case of 2,6-HNA, the α-methoxy ketone 42, which was not detected among the photoproducts
Photo, thermal and chemical degradation of riboflavin
Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208
- , 267, 373 and 444 nm in the UV and visible regions in aqueous solution and is degraded into various photoproducts on exposure to light [1]. These products include formylmethylflavin (FMF), lumichrome (LC), lumiflavin (LF), carboxymethylflavin (CMF), 2,3-butanedione, a β-keto acid and a diketo compound
- cyclodehydroriboflavin (CDRF) [21][30][35]. The structures of RF and its photoproducts are shown in Figure 1. FMF is an intermediate in the photodegradation of RF and is more sensitive to light than RF [15][16][17][27][32][33]. It is hydrolyzed to LC and LF [18][19][22][23][24][25][26][27][28][29][30][31][32][33] and is
- oxidized to CMF [20][27][32]. Both LC and LF are also sensitive to light, with LC having relatively better stability [36]. The nature of the photoproducts of RF depends on the reaction conditions such as solvent, pH, buffer kind and concentration, oxygen content, light intensity and wavelengths
Direct and indirect single electron transfer (SET)-photochemical approaches for the preparation of novel phthalimide and naphthalimide-based lariat-type crown ethers
Beilstein J. Org. Chem. 2014, 10, 514–527, doi:10.3762/bjoc.10.47
- corresponding polyether side chain containing the lariat-type azacrown ethers 47a–c exclusively (Scheme 11). As observed in earlier studies [34], the initially formed photoproducts undergo in situ dehydration to produce the vinyl sulfide products 46a–c [82]. The photoreactions shown in Scheme 10 and Scheme 11
Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor
Beilstein J. Org. Chem. 2013, 9, 2015–2021, doi:10.3762/bjoc.9.237
- ][7][8][9]. The narrow reaction channels guarantee efficient penetration of light and yield improved photonic efficiencies [10][11]. Likewise, the removal of the photoproducts from the irradiated area minimizes the risk of photodecompositions or secondary photoreactions [12][13]. Of the many
Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution
Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217
- a plausible way to enhance the reaction selectivity of the syn-HH dimer. The 1H NMR spectra of the crude photoproducts indeed showed a striking effect from changes in the salt concentration. The signals of the syn-HT and anti-HH isomers significantly diminished as shown in Figure 6. At a high salt
- , photoproducts are predictable by quantum mechanical optimization of the corresponding dimeric aggregates in vacuo. This work also showed that the addition of salt can further improve supramolecular control by suppression of the free photoactive species. Experimental General: Guests (ANT, ACE, and COU) and
- irradiation for 12 h at room temperature under a nitrogen atmosphere, the photoproducts formed were extracted with chloroform and then analyzed by 1H NMR [34]. No starting material was found anymore after this time of reaction. It is worth mentioning that a precipitate was formed after irradiation of the
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