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Journal articles on the topic 'PHOTOCHEMICAL ISOMERISM'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

Bitterwolf, Thomas E. "Photochemical nitrosyl linkage isomerism/metastable states." Coordination Chemistry Reviews 250, no. 9-10 (2006): 1196–207. http://dx.doi.org/10.1016/j.ccr.2005.12.016.

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2

Hatcher, Lauren, and Paul Raithby. "Photocrystallographic and kinetic studies of metastable linkage isomers." Acta Crystallographica Section A Foundations and Advances 70, a1 (2014): C773. http://dx.doi.org/10.1107/s2053273314092262.

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The ability of a molecular system to reversibly convert between two distinct states on photoactivation is desirable for many real-world applications, including photo-switchable device media. When induced in the solid-state, the process can be studied by crystallography and specifically photocrystallographic methods have contributed greatly to this diverse research area. The process of linkage isomerism has proved popular for photocrystallographic study. While the atomic rearrangements involved in the process are large enough to be determined from diffraction data, the changes are also moderate

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3

Lopes Jesus, A. J., Cláudio M. Nunes, Gil A. Ferreira, Kiarash Keyvan, and R. Fausto. "Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations." Molecules 29, no. 15 (2024): 3497. http://dx.doi.org/10.3390/molecules29153497.

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The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (λ = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitri

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4

Ferrer, Íngrid, Xavier Fontrodona, Montserrat Rodríguez, and Isabel Romero. "Ru(ii)-dmso complexes containing azole-based ligands: synthesis, linkage isomerism and catalytic behaviour." Dalton Transactions 45, no. 7 (2016): 3163–74. http://dx.doi.org/10.1039/c5dt04376j.

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Photochemical ligand substitution in acetonitrile and chloroform, together with the kinetics of dmso linkage isomerization, are investigated in new Ru(ii)-dmso complexes that are also active as nitrile hydration catalysts.

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5

Custodio Castro, Michelle T., Carlos O. Della Védova, Helge Willner, and Rosana M. Romano. "Ar-Matrix Studies of the Photochemical Reaction between CS2 and ClF: Prereactive Complexes and Bond Isomerism of the Photoproducts." Photochem 2, no. 3 (2022): 765–78. http://dx.doi.org/10.3390/photochem2030049.

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In this work, prereactive complexes, reaction products, and conformational preferences derived from the photochemical reaction between CS2 and ClF were analyzed following the codeposition of the reactants trapped in argon matrices at cryogenic temperatures. After codeposition of CS2 and ClF diluted in Ar, the formation of van der Waals complexes is observed. When the mixture is subsequently irradiated by means of broad-band UV-visible light (225 ≤ λ ≤ 800 nm), fluorothiocarbonylsulfenyl chloride (FC(S)SCl) and chlorothiocarbonylsulfenyl fluoride (ClC(S)SF) are produced. These species exist as

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6

Ichino, Rina, Atsuya Momotake, and Tatsuo Arai. "Photochemical properties of enediyne-cored dendrimers bearing naphthalenes at the periphery." Canadian Journal of Chemistry 97, no. 2 (2019): 112–19. http://dx.doi.org/10.1139/cjc-2018-0128.

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A novel series of trans and cis enediyne-cored dendrimers bearing naphthalenes at the periphery were synthesized and their photochemical properties were examined. The trans/cis isomer ratio in the photostationary state was dependent on the excitation site in the dendrimers. When the enediyne core was selectively excited, the trans/cis isomer ratio in the photostationary state was either around 50/50 or a cis-rich mixture in all dendrimers due to the larger molar extinction coefficient of the trans-enediynes. On the other hand, when naphthalene was excited, a trans-rich mixture was unexpectedly

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7

Fabian, Jürgen, and Peter Birner. "A theoretical study of the disulfide/dithione valence isomerism." Collection of Czechoslovak Chemical Communications 53, no. 9 (1988): 2096–115. http://dx.doi.org/10.1135/cccc19882096.

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According to MNDO calculations on 1,2-dithiete (IIIa), 1,2-dithiin (IVa) and 3,4-dimethylene-1,2-dithiane (Va) the closed-ring compounds are thermodynamically more stable than the open-chain compounds whereas the reverse holds for 4-methylene-1,2-dithiole (VIa). Substitution of the exocyclic CH2 group of VIa by O, S, NH, and OH+ stabilizes its cyclic mesoionic structure. The low triplet state energy of VIa and of some derivatives relative to the lowest singlet state energy signalizes the biradicaloid nature of these electronic structures. Replacement of hydrogen of the methine groups adjacent

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8

Champenois, E. G., D. M. Sanchez, J. Yang, et al. "Conformer-specific photochemistry imaged in real space and time." Science 374, no. 6564 (2021): 178–82. http://dx.doi.org/10.1126/science.abk3132.

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Conformer-specific dynamics Conformation-dependent dynamics play an important role in organic chemistry syntheses such as electrocyclic reactions, as well as in biological processes such as protein folding. However, current time-resolved experimental methods struggle to distinguish conformers from each other, and conformational isomerism is usually analyzed through reactant and product distributions. Using a combination of mega–electron volt ultrafast electron diffraction and quantum wave packet simulations, Champenois et al . directly followed the photochemical electrocyclic ring opening of t

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9

Debatra, Narayan Neogi, Singh Chhetri Satyadeep, Das Purak, Narayan Biswas Achintesh, Choudhury Amitava, and Bandyopadhyay Pinaki. "Role of auxiliary donors in tuning the selectivity of C-H activation in arylazonaphthalenes by palladium(II) : Isolation and photoisomerization of isomeric cyclopalladates." Journal of Indian Chemical Society Vol. 92, Dec 2015 (2015): 1783–90. https://doi.org/10.5281/zenodo.5599293.

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Department of Chemistry, University of North Bengal, Siliguri-734 013, West Bengal, India <em>E-mail</em> : pbchem@rediffmail.com Department of Chemistry, Rishi Bankim Chandra College, Naihati-743 165, West Bengal, India Department of Chemistry, Siliguri College, Siliguri-734 001, West Bengal, India Department of Chemistry, Missouri S & T, Rolla, MO 65409-0010, USA Selective activation of C2(naphthyl)-H and C8(naphthyl)-H bonds in a group of substrates having a diazene function as primary donor along with thioether or sulfinyl groups as auxiliary donors has been achieved by palladium(II) a

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10

Yılmaz, Yusuf, John Mack, M. Kasım Şener, Mehmet Sönmez, and Tebello Nyokong. "Synthesis, photophysicochemical properties and TD-DFT calculations of tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanines." Journal of Porphyrins and Phthalocyanines 18, no. 04 (2014): 326–35. http://dx.doi.org/10.1142/s1088424614500047.

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The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1 H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn ( II ) complex (4) was fou

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11

Szymańska-Buzar, Teresa, та Krystyna Kern. "NMR studies of the structure, isomerism and photochemical reactions of trans-[W(CO)4(η2-alkene)2] complexes". Journal of Organometallic Chemistry 592, № 2 (1999): 212–24. http://dx.doi.org/10.1016/s0022-328x(99)00517-3.

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12

Hatcher, Lauren E., Edward J. Bigos, Mathew J. Bryant та ін. "Thermal and photochemical control of nitro–nitrito linkage isomerism in single-crystals of [Ni(medpt)(NO2)(η2-ONO)]". CrystEngComm 16, № 35 (2014): 8263–71. http://dx.doi.org/10.1039/c4ce00675e.

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[Ni(medpt)(NO<sub>2</sub>)(η<sup>2</sup>-ONO)] displays an equilibrium between the η<sup>1</sup>-NO<sub>2</sub> and the η<sup>1</sup>-ONO linkage isomers between 150–298 K; upon photoactivation at 100 K the percentage of the η<sup>1</sup>-ONO isomer increases.

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13

Hill, Ross H., and Bentley J. Palmer. "The mechanism of the photochemical cis-trans isomerism of (.eta.5-C5Me5)Re(CO)2X2 (X = Me, Cl, Br, I)." Organometallics 8, no. 7 (1989): 1651–55. http://dx.doi.org/10.1021/om00109a012.

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14

Thornley, Wyatt A., and Thomas E. Bitterwolf. "Evidence for Photochemical Linkage Isomerism of the Phenylazo Ligand in M(CO)2(N2Ph)(PPh3)2Cations (M = Fe and Ru)." European Journal of Inorganic Chemistry 2015, no. 11 (2015): 1946–49. http://dx.doi.org/10.1002/ejic.201403211.

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15

Muya, Jules Tshishimbi, Biswa Ranjan Meher, Subash Chandra Sahoo, and Hoeil Chung. "A theoretical insight into the role of counter anions and their interactions in nitropentaamminecobalt(III) toward linkage isomerism‐induced photochemical motion." International Journal of Quantum Chemistry 119, no. 14 (2019): e25929. http://dx.doi.org/10.1002/qua.25929.

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16

De Candia, Ariel G., Juan P. Marcolongo, Roberto Etchenique, and Leonardo D. Slep. "Widely Differing Photochemical Behavior in Related Octahedral {Ru-NO}6Compounds: Intramolecular Redox Isomerism of the Excited State Controlling the Photodelivery of NO." Inorganic Chemistry 49, no. 15 (2010): 6925–30. http://dx.doi.org/10.1021/ic100491g.

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17

Ginocchietti, Gabriella, Ugo Mazzucato, and Anna Spalletti. "Protonation effect on the excited state behaviour of some aza-analogues ofEE-distyrylbenzene." International Journal of Photoenergy 6, no. 4 (2004): 241–50. http://dx.doi.org/10.1155/s1110662x04000315.

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The photobehaviour of four aza-analogues ofEE-distyrylbenzene bearing the heteroatom in the two side rings [1,4-di-(2-pyridylethenyl)benzene] or in the central ring [2,5-di-(phenylethenyl)pyridine, 2,6-di(phenylethenyl)pyridine and the corresponding diene, 2,6-di(phenylbutadienyl)pyridine] has been investigated in aqueous solutions at pH 2 and 9, where the molecules are in mono-protonated and neutral forms, respectively. The type of conjugation, linear for the first two compounds and crossed for the others, is particularly important in determining the spectral and photochemical properties. The

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18

Itoh, S., та S. Onishi. "Kinetic study of the photochemical changes of (ZZ)-bilirubin IX α bound to human serum albumin. Demonstration of (EZ)-bilirubin IX α as an intermediate in photochemical changes from (ZZ)-bilirubin IX α to (EZ)-cyclobilirubin IX α". Biochemical Journal 226, № 1 (1985): 251–58. http://dx.doi.org/10.1042/bj2260251.

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The present study was performed to elucidate why the photochemical reaction of (ZZ)-bilirubin bound to human serum albumin is singularly selective, and only one of the two (EZ)- and (ZE)-bilirubins, the (ZE)-isomer, is produced. In a kinetic study of the photochemical reaction in vitro, the sum of the relative rate constants of photochemical transformation of (EZ)-bilirubin into both (EZ)-cyclobilirubin and (ZZ)-bilirubin, with a significant preference for the former, was proved to be considerably larger than that of the transformation of (ZZ)-bilirubin into (EZ)-bilirubin. Therefore only one

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19

Marciniak, Bronislaw, and Krzysztof Bobrowski. "Photo- and Radiation-Induced One-Electron Oxidation of Methionine in Various Structural Environments Studied by Time-Resolved Techniques." Molecules 27, no. 3 (2022): 1028. http://dx.doi.org/10.3390/molecules27031028.

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Oxidation of methionine (Met) is an important reaction that plays a key role in protein modifications during oxidative stress and aging. The first steps of Met oxidation involve the creation of very reactive and short-lived transients. Application of complementary time-resolved radiation and photochemical techniques (pulse radiolysis and laser flash photolysis together with time-resolved CIDNP and ESR techniques) allowed comparing in detail the one-electron oxidation mechanisms initiated either by ●OH radicals and other one-electron oxidants or the excited triplet state of the sensitizers e.g.

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20

Surinder, Berar, Jindal Pooja, Berar Urmila, Bhatia Rimpy, Chaudhary Ashu, and C. Kamboj Ramesh. "Photochemical and thermal transformations of some diallyl-1-benzoylcyclopropanes." Journal of Indian Chemical Society Vol. 91, Dec 2014 (2014): 2271–82. https://doi.org/10.5281/zenodo.5746509.

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Department of Chemistry, Kurukshetra University, Kurukshetra-136 119, Haryana, India <em>E-mail </em>: rckamboj@rediffmail.com <em>Manuscript received online 18 April 2013, revised 12 July 2014, accepted 17 July 2014</em> Photochemical and thermal transformations of diallyl-1-benzoylcyclopropanes to the exotic isomeric alkenes have been described. The products formation is exclusively controlled by the nature of substituents on the cyclopropane ring as well as on the aromatic ring in benzoyl group. The stimulus behind this is the thermostability of the intermediate 1,4-biradical produced photo

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21

Leigh, William J., J. Alberto Postigo, and K. C. Zheng. "Cyclobutene photochemistry. Adiabatic photochemical ring opening of alkylcyclobutenes." Canadian Journal of Chemistry 74, no. 6 (1996): 951–64. http://dx.doi.org/10.1139/v96-105.

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The photochemistry of the cis and trans isomers of a series of dimethylbicyclo[n 2.0]alk-(n + 2)-enes (n = 2–5) (bicyclic cyclobutene derivatives in which the C=C bond is shared by the two rings) in pentane solution is described. Irradiation of these compounds using monochromatic 193- or214-nm light sources results in ring opening to yield the corresponding 1,2-bis(1-ethylidene)cycloalkanes (C4–C7) in high chemical and quantum yields. In all cases, the reaction proceeds with a high (70–90%) degree of disrotatory stereoselectivity. Quantum yields for direct cis,trans photoisomerization of the i

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22

Polukhtine, Andrei, Grigori Karpov, Dinesh R. Pandithavidana, Alexander Kuzmin, and Vladimir V. Popik. "Photochemical Triggering of the Bergman and Myers - Saito Cyclizations." Australian Journal of Chemistry 63, no. 7 (2010): 1099. http://dx.doi.org/10.1071/ch10185.

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Two strategies for the photochemical generation of reactive enediyne compounds and their subsequent cycloaromatization to p-benzyne or α,3-didehydrotoluene derivatives are discussed in this account. The first method employs a photo-Wolff reaction of stable 11- or 12-membered ring precursor enediynes containing the 2-diazo-1,3-diketone moiety. Irradiation of these compounds results in ring contraction and the formation of two isomeric enediynes possessing an enolized β-ketoester fragment. One of the isomers undergoes the conventional Bergman cyclization, whereas the other isomerizes into the en

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23

Mattioli, Roberto, Daniel Di Risola, Rodolfo Federico, et al. "Effect of Natural Deep Eutectic Solvents on trans-Resveratrol Photo-Chemical Induced Isomerization and 2,4,6-Trihydroxyphenanthrene Electro-Cyclic Formation." Molecules 27, no. 7 (2022): 2348. http://dx.doi.org/10.3390/molecules27072348.

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trans-Resveratrol is a natural bioactive compound with well-recognized health promoting effects. When exposed to UV light, this compound can undergo a photochemically induced trans/cis isomerization and a 6π electrochemical cyclization with the subsequent formation of 2,4,6-trihydroxyphenanthrene (THP). THP is a potentially harmful compound which can exert genotoxic effects. In this work we improved the chromatographic separation and determination of the two resveratrol isomers and of THP by using a non-commercial pentafluorophenyl stationary phase. We assessed the effect of natural deep eutec

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24

Arnold, Donald R., and Miles S. Snow. "The photochemical nucleophile–olefin combination, aromatic substitution reaction (Part 2): methanol – cyclic olefins, 1,4-dicyanobenzene." Canadian Journal of Chemistry 66, no. 12 (1988): 3012–26. http://dx.doi.org/10.1139/v88-467.

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Direct irradiation of acetonitrile–methanol (3:1) solutions of 1,4-dicyanobenzene and the cyclic olefins, cyclohexene, 1-methylcyclohexene, norbornene, and 2-methylnorbornene, leads to formation of regio- and stereoisomers of the 1:1:1 (alcohol:olefin:aromatic) adducts. This reaction can be photosensitized by electron transfer; addition of electron donors, biphenyl or phenanthrene, to the irradiation mixture generally increases the efficiency and yield of adduct formation. The efficiency of the reaction and the ratio of isomeric adducts are also affected by the addition of salts, particularly

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25

Newland, Mike J., Gerard J. Rea, Lars P. Thüner, et al. "Photochemistry of 2-butenedial and 4-oxo-2-pentenal under atmospheric boundary layer conditions." Physical Chemistry Chemical Physics 21, no. 3 (2019): 1160–71. http://dx.doi.org/10.1039/c8cp06437g.

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26

Hatcher, Lauren E., and Paul R. Raithby. "Solid-state photochemistry of molecular photo-switchable species: the role of photocrystallographic techniques." Acta Crystallographica Section C Crystal Structure Communications 69, no. 12 (2013): 1448–56. http://dx.doi.org/10.1107/s010827011303223x.

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Over the last 30 years, the single-crystal photocrystallographic technique has been developed to determine the three-dimensional crystal and molecular structures of metastable species which have been generated in the crystal photochemically. Transition-metal complexes that have been investigated using this methodology include complexes that contain nitrosyl, dinitrogen, sulfur dioxide and nitrite ligands, all of which form new linkage isomers in the solid state when photoactivated by light of the appropriate wavelength. Both steric and electronic factors determine the level of the conversion f

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27

D’Auria, Maurizio. "A Theoretical Study on the Photochemical Isomerization of 2,6-Dimethylpyrazine." Organics 3, no. 2 (2022): 95–101. http://dx.doi.org/10.3390/org3020007.

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DFT calculations on the photoisomerization of 2,6-dimethylpyrazine allowed us to confirm the role of benzvalene isomers in the isomerization of hexatomic heterocyclic compounds. 2,6-Dimethylpyrazine in the excited singlet states can be converted into the corresponding Dewar isomers. If the S2 state is populated, two Dewar isomers can be obtained, while the S1 state allows the formation of only one of the possible Dewar isomers. Both Dewar isomers can be converted into the benzvalene isomer, that is, the precursor of 4,5-dimethylpyrimidine, the reaction product. In fact, the benzvalene isomer c

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28

Matonic, John H., Sue Jane Chen, Spiros P. Perlepes, Kim R. Dunbar, and George Christou. "Isomerism in the Mo2(.mu.-O2CCF3)4/bpy reaction system: thermal and photochemical conversion of the ion-pair complex [Mo2(.mu.-O2CCF3)2(bpy)2](O2CCF3)2 to the unbridged neutral isomer Mo2(.eta.1-O2CCF3)4(bpy)2." Journal of the American Chemical Society 113, no. 21 (1991): 8169–71. http://dx.doi.org/10.1021/ja00021a054.

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29

Hauke, S., A. K. Dutta, V. B. Eisenbeis та ін. "Photolysis of cell-permeant caged inositol pyrophosphates controls oscillations of cytosolic calcium in a β-cell line". Chemical Science 10, № 9 (2019): 2687–92. http://dx.doi.org/10.1039/c8sc03479f.

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30

Budyka, M. F., V. M. Li, and N. I. Potashova. "Spectral and photochemical properties of isomeric styrylbenzoquinolines." High Energy Chemistry 47, no. 3 (2013): 107–14. http://dx.doi.org/10.1134/s0018143913030028.

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31

Fleming, S. A., L. Renault, E. C. Grundy, and J. A. Pincock. "The photochemistry of ring-substituted cinnamyl acetates." Canadian Journal of Chemistry 84, no. 9 (2006): 1146–54. http://dx.doi.org/10.1139/v06-140.

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The photochemistry of the (E)-cinnamyl acetates ((E)-1-aryl-3-propenyl acetates, 8a–8e) with substituents H, 4-CH3O, 3-CH3O, 4-CF3, and 3-CF3, respectively, was examined in both cyclohexane and methanol solvents. Alkene isomerization (E to Z) occurred more efficiently than other reactions and evidence is presented that this process occurs from the excited triplet state. In a slower process, 1,3-migration of the acetoxy group led to the rearranged 3-aryl-3-propenyl acetate isomers (9a–9e) as the major pathway, particularly in cylohexane. In methanol, the isomeric ethers 3-aryl-3-methoxypropene

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32

Lunardi, Claure N., Jeane C. G. Rotta, and Antonio C. Tedesco. "Zinc tetranitrophthalocyanine: isomer separation and photophysical photobiological evaluation in J774A tumor cells." Journal of Porphyrins and Phthalocyanines 07, no. 07 (2003): 493–99. http://dx.doi.org/10.1142/s1088424603000628.

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The synthesis of zinc tetranitrophthalocyanine ( T 4 NO 2 ZnPc ) was carried out and two structural isomers ( C 2v and C s) were separated by column chromatography and characterized by 400 MHz proton nuclear resonance spectroscopy and absorption spectroscopy. The photophysical and photobiological parameters for isomers C 2v and C s were determined in solution and in the presence of macrophage cell culture (J774A). The results obtained clearly indicated that the photophysical, photochemical and photobiological properties of the two isomers were different and each isomer showed a different biolo

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33

Bohnwagner, Mercedes V., Irene Burghardt, and Andreas Dreuw. "Regular and red-shifted fluorescence of the donor–acceptor compound 5-(1H-pyrrole-1-yl)thiophenecarbonitrile (TCN) is efficiently quenched by internal modes of thiophene." Physical Chemistry Chemical Physics 19, no. 21 (2017): 13951–59. http://dx.doi.org/10.1039/c7cp01460k.

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The photochemical properties of thiophene analogs of N-pyrrolobenzonitrile (PBN), notably the two isomers 5-(1H-pyrrole-1-yl)thiophene-2-carbonitrile (2-TCN) and 5-(1H-pyrrole-1-yl)thiophene-3-carbonitrile (3-TCN) have been investigated.

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34

Geng, Wei Wei, Shou Zhi Pu, and Shi Qiang Cui. "Synthesis and Properties of a Novel Unsymmetrical Diarylethene with Five and Six Ring Aryls." Advanced Materials Research 490-495 (March 2012): 3676–80. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.3676.

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A novel photochromic diarylethene with thiophene and benzene compound, 1-{[2-methyl-5-(1, 3-dioxolane)-3-thienyl]}-2-(2-cyanophenyl)perfluorocyclopentene(1a) has been synthesized. Its photochemical properties, including photochromic behavior and fluorescent features, have been investigated in detail. The compound showed good photochromism both in solution and in PMMA. The diarylethene exhibited a fluorescence switches along with the photochromism from open-ring isomers to closed-ring isomers. When irradiated by UV light, the photocyclization reaction was occurred and the emission intensity of

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35

Častulík, Jakub, Jaroslav Jonas, and Ctibor Mazal. "Stereoselective 1,3-Dipolar Cycloaddition of a Nitrile Ylide Photochemically Generated from 2,3-Diphenyl-2H-azirine to Substituted Methylene Lactones." Collection of Czechoslovak Chemical Communications 65, no. 5 (2000): 708–16. http://dx.doi.org/10.1135/cccc20000708.

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The nitrile ylide photochemically generated from 2,3-diphenyl-2H-azirine adds to both isomers of 3-(tosyloxymethylene)tetrahydrofuran-2-one with excellent regio- and stereoselectivity giving spiroheterocyclic products in moderate yields. X-Ray structure determination showed dibutolactone to have the E-configuration; the corresponding Z-isomer was prepared photochemically.

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36

Huneck, Siegfried, Jürgen Schmidt, and Andrea Porzel. "Zur Chemie der Roccellsäure / On the Chemistry of Roccellic Acid." Zeitschrift für Naturforschung B 49, no. 4 (1994): 561–68. http://dx.doi.org/10.1515/znb-1994-0420.

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The isomerization of roccellic acid to threo-roccellic acid has been investigated. Reduction of dimethyl roccellate with LiAlH4 gave the corresponding diol which yielded on oxidation with Jones' reagent two isomeric γ-lactones. 1-Methyl roccellic amide has been transformed by a photochemical reaction to the δ-lactone acaranoic acid. Two copper complexes of roccellimide have been prepared.

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37

Kuzmič, Petr, Libuše Pavlíčková, and Milan Souček. "Photochemical hydrolysis of some nitrophenyl acetates." Collection of Czechoslovak Chemical Communications 51, no. 6 (1986): 1293–300. http://dx.doi.org/10.1135/cccc19861293.

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Nitro substituent exhibits a meta-activating effect on the course of photochemical hydrolysis of phenyl acetates since UV photolysis of isomeric 4- and 3-nitrophenyl acetates in neutral aqueous solution leads to the formation of the corresponding phenols with quantum yields 0.002 and 0.006, respectively; 2-methoxy-4-nitro- and 2-methoxy-5-nitrophenyl acetates showed still greater difference in their photochemical reactivity (Φr 0.002 and 0.129, respectively). Quenching of the photohydrolysis of the latter compound with 2,4-hexadienoic acid indicates the participation of a triplet state with th

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38

Fodor, Lajos, and David B. MacLean. "Isomeric 6H,8H-naphthyridino-1,3-benzothiazin-8-ones." Canadian Journal of Chemistry 65, no. 3 (1987): 636–38. http://dx.doi.org/10.1139/v87-109.

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The synthesis of the ring system present in two of the four possible isomeric 6H,8H-naphthyridino-1,3-benzothiazines is reported here for the first time. 2,3-Dimethoxy-6H,8H-[2,7]naphthyridino[2,3-c][1,3]benzothiazin-8-one (5) and several related compounds have been prepared by both chemical and photochemical methods. 2,3-Dimethoxy-6H,8H-[1,6]naphthyridino[6,7-c][1,3]benzothiazin-8-one (9) has been isolated in 15% yield along with 5 in 38% yield on irradiation of 6,7-dimethoxy-3-nicotinoyl-4-methylidene-2H-1,3-benzothiazine (8).

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39

Mlakić, Milena, Hana Perinić, Vitomir Vušak, et al. "Photochemical Transformations of Diverse Biologically Active Resveratrol Analogs in Batch and Flow Reactors." Molecules 29, no. 1 (2023): 201. http://dx.doi.org/10.3390/molecules29010201.

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Previous biological tests have shown that some resveratrol analogs exhibited significant antioxidative and cholinesterase inhibitory potential, as evidenced by lower IC50 values compared to the established standards, resveratrol and galantamine, respectively. Photochemical transformations were made in parallel on these compounds in the presence of porphyrin photocatalysts in batch and microreactor, showing the significant advantage of flow photochemistry concerning productivity, selectivity, and yields. In this research, the products of photocatalysis and direct irradiation (photolysis) of res

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40

Vidal, Sara, Marta Izquierdo, Wai Kit Law, et al. "Photochemical site-selective synthesis of [70]methanofullerenes." Chemical Communications 52, no. 86 (2016): 12733–36. http://dx.doi.org/10.1039/c6cc06072b.

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Methanofullerenes such as the well-known [70]PCBM are commonly synthesized under harsh conditions to obtain the product as a mixture of site-isomers (namely α, β and minor γ) due to the D<sub>5h</sub> symmetry of the C<sub>70</sub> cage. α-[70]siteisomers are selectively prepared under light and mild conditions with minor or negligible β-[70]siteisomers formation.

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41

Grabchev, Ivo, and Vladimir Bojinov. "Photoisomerization of Triazine-stilbene Fluorescent Brighteners in Solution and in their Copolymers with Styrene." Zeitschrift für Naturforschung A 55, no. 9-10 (2000): 833–36. http://dx.doi.org/10.1515/zna-2000-9-1014.

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Abstract The paper reports on the photochemical trans-cis isomerization of some new polymerizable triazine-stilbene fluorescent brighteners and their copolymers with styrene in aqueous and ethanol solutions. A dependence of trans-cis isomers in solution equilibrium and in solid polymeric films on the nature of the substituent in the triazine ring has been found.

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42

Sauro, Vittorio A., and Mark S. Workentin. "The redox properties of ferrocenyl-substituted aryl azines." Canadian Journal of Chemistry 80, no. 3 (2002): 250–62. http://dx.doi.org/10.1139/v02-019.

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A series of ferrocenyl substituted azines (1-Fc/Ar, where Ar = 4-NO2C6H4, 4-CNC6H4, 4-OCH3C6H4, C5H4N, ferrocene, anthracene, and pyrene) were investigated by electrochemical and photochemical techniques. All the 1-Fc/Ar exhibited oxidation waves within 60 mV of each other, consistent with the expected oxidation of the ferrocene moiety. The reduction properties of 1-Fc/Ar is governed by the nature of the Ar substituent. The standard reduction potentials suggest that ferrocene has comparable electron donating abilities as a 4-methoxyphenyl and 4-dimethyl aminophenyl group. The anthracenyl azine

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43

Wolff, Thomas. "Temperature Dependence of Regioselectivity and Excimer Equilibrium in the Photodimerization of 9-Methylanthracene." Zeitschrift für Naturforschung A 40, no. 11 (1985): 1105–7. http://dx.doi.org/10.1515/zna-1985-1105.

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The temperature dependence of the ratio of formation of the two isomeric products (head-to-tail- and head-to-head-photodimer) of the photodimerization of 9-methylanthracene was measured in chloroform, ethanol, diethyl ether, and methylcyclohexane as solvents. The ratio increases or decreases with temperature depending on the solvent. One of the isomeric photoproducts was converted photochemically into the other one, indicating an equilibrium of excimer precursors of the products.

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44

Šebek, Pavel, Petr Sedmera, and Josef Kuthan. "Photochemical Transformations of 2,4,4,6-Tetraphenyl-4H-thiopyran-1,1-dioxide and Some Its para-Substituted Derivatives." Collection of Czechoslovak Chemical Communications 58, no. 4 (1993): 869–81. http://dx.doi.org/10.1135/cccc19930869.

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1,2,4,5-Tetrasubstituted cyclopentadienes VIa-VIf or phenanthrene derivative VIII, respectively, were obtained as the main photoproducts upon irradiation of sulfones Ia-If and II in acetonitrile, methanol or benzene. Bridged isomers Va-Vd were isolated from the reaction of Ia-Id carried out in acetonitrile. Probable course of the investigated photochemical transformations of 4H-thiopyran-1,1-dioxides is discussed.

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45

Böhme, Thomas, Mari Egeland, Marianne Lorentzen, et al. "Regiospecific Photochemical Synthesis of Methylchrysenes." Molecules 28, no. 1 (2022): 237. http://dx.doi.org/10.3390/molecules28010237.

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Methylated polycyclic aromatic hydrocarbons (PAHs) are suspected to be some of the toxic compounds in crude oil towards marine life and are needed as single compounds for environmental studies. 1-, 3- and 6-methylchrysene (3a,b,c) were prepared as single isomers by photochemical cyclization of the corresponding stilbenoids in the Mallory reaction using stoichiometric amounts of iodine in 82-88% yield. 2-methylchrysene (3d) was prepared by photochemical cyclization where the regioselectivity was controlled by elimination of an ortho-methoxy group under acidic oxygen free conditions in 72% yield

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46

Dong, Xiao Rong, Le Le Ma, and Gang Liu. "Photochromic and Kinetics Properties of a New Symmetrical Diarylethene Containing a Terminal Hydroxyl." Applied Mechanics and Materials 473 (December 2013): 65–68. http://dx.doi.org/10.4028/www.scientific.net/amm.473.65.

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A symmetrical photochromic diarylethene1ahas been synthesized. Its photochemical properties, including photochromic behavior and kinetics, have been investigated in detail. The compound showed good photochromism both in solution and in solid state. The back irradiation by appropriate wavelength visible light regenerated its open-ring isomers and recovered the original emission intensity. Using diarylethene1aas recording medium, polarization holographic optical recording was carried out successfully.

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47

Mor, Satbir, Som N. Dhawan, Mona Kapoor, and Devinder Kumar. "Photochemical synthesis of isomeric (E/Z)-3-alkylidene-3H-isobenzofuranones." Tetrahedron 63, no. 3 (2007): 594–97. http://dx.doi.org/10.1016/j.tet.2006.11.021.

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48

Su, Shih-Hao, and Ming-Der Su. "Photochemical rearrangement reactions of bicyclic molecules that contain a cyclopropane ring." New Journal of Chemistry 42, no. 14 (2018): 11438–49. http://dx.doi.org/10.1039/c8nj01795f.

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Our theoretical observations indicate that for [2.1.0], [3.1.0], [4.1.0], and [5.1.0] molecules, the quantum yields of the tautomeric keto forms are larger than those of the corresponding enol isomers.

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49

Šandrik, Róbert, Pavol Tisovský, Klaudia Csicsai, et al. "ON/OFF Photostimulation of Isatin Bipyridyl Hydrazones: Photochemical and Spectral Study." Molecules 24, no. 14 (2019): 2668. http://dx.doi.org/10.3390/molecules24142668.

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Four novel isatin hydrazones containing bipyridyl fragments were synthesized as potential ON/OFF switches. Hydrazone Z-isomers exhibit high thermal stability. The characteristic photochemical reaction for all studied hydrazones is the Z–E isomerization in CHCl3. After irradiation of hydrazones 1 and 2 in dimethylformamide (DMF), the photoreaction products are tautomers. When using light with the appropriate wavelength, the photo-tautomerization reaction is reversible. In these conditions, studied hydrazones have ON/OFF switch properties. In the case of hydrazones 1 and 2, by alternating heat a

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50

Guseva, M. A., E. V. Bermesheva, P. P. Chapala, and M. V. Bermeshev. "One-step and selective approach to silicon-containing exo-norbornenes." Доклады Академии наук 486, no. 2 (2019): 189–92. http://dx.doi.org/10.31857/s0869-56524862189-192.

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One-step and selective approach to the synthesis of Si-containing exo-norbornenes has been developed based on hydrosilylation reaction of norbornadiene-2,5 with unactivated silanes using Pd-complexes in the presence of bulky ligands. This approach leads to only exo-isomers of norbornene derivatives. The absence of alkylation step by organometallic compounds or photochemical isomerization makes the suggested approach promising for the synthesis of new polymeric materials with desired properties.

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