When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• , in the 21st century there is a real renaissance for photocatalysis, with great advances achieved mainly in visible-light-mediated reactions [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Various photosensitizers, initially based on noble metals (such as Ir and Ru polypyridine complexes

Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• same starting material is a highly attractive divergent approach, though it represents significant synthetic challenges. Recent advances in visible-light photocatalysis, mediated by visible-light-absorbing photosensitizers, have allowed ready access to complex molecules in a controlled manner, where

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• conjugated photosensitizers show increasing potential in photocatalysis since they combine both photo- and electrochemical properties which can substitute available metalloorganic photocatalysts. Batch and continuous-flow approaches are presented highlighting the relevance of enabling technologies for the

• pericyclic reactions with olefins and dienes, and the second deals with heteroatom oxidations carried out by singlet oxygen. Review Porphyrins as photoredox catalysts Porphyrins and metalloporphyrins have been extensively studied as photosensitizers in singlet oxygen generation, but underexploited as

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• shed more light on some mechanistic pathways and set the key foundation for the further use as photoinitiators or photocatalysts. In 1961, Hammond and co-workers studied the cis/trans isomerization of the piperylenes (1,3-pentadienes) 61 and 62 in the presence of carbonyl compounds as photosensitizers

• various aldehydes and ketones that were used as photosensitizers (Scheme 15) [51]. In more detail, a solution of cis-piperylene (61) in benzene in the presence of various carbonyl compounds was irradiated using a Hanovia quartz immersion reactor. It was shown that compounds that had a triplet state energy

• presence of the nickel catalyst and a base via a typical oxidative addition, insertion, and reductive elimination sequence to afford the desired product (Scheme 29). In the absence of K2HPO4, only traces of the desired product were detected. Other known photosensitizers, such as acetone (4), acetophenone

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• metal ions. In this process, basically, in the presence of photoactive materials (PAs) such as photoinitiators, photosensitizers or photoredox catalysts, the photoexcitation of a photoredox system results in formation of reactive radicals. Those reactive radicals add monomer and the polymerization

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• action via its combination with the photosensitizer. It is worth mentioning that, mainly in dermatology, even UVB irradiation is considered of therapeutic use [16][17][18]. Besides the anticancer activities of photosensitizers [19][20][21], “post-antibiotic era” is experimenting with photosensitizers as

• amidoxime, ethanone oxime and aldoxime (VI, VII, VIII, R1 = p-pyridyl, Figure 1) as DNA photosensitizers. Based on our previous experimental results with o-, m- and p-pyridine oximes as carriers of the carboxylic [9] and sulfonic [11] ester conjugates, we proclaimed p-substituted pyridine ring as the most

• barriers are very large, 29.37 kcal/mol for T1 and 31 kcal/mol for the S1 state. Hence, 11 does not show any photoreactivity, in accordance with our experimental results. Photoexcitation in the presence of a triplet state energy activator and a triplet state quencher Triplet photosensitizers (TPSs) or

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• conversions [7]. Porphyrins have been extensively studied as potential photosensitizers in a photodynamic therapy (PDT) [8][9], a promising treatment modality for several cancer and infectious diseases. In PDT, light, O2, and a photosensitizing drug are combined to produce a selective therapeutic effect via

• the generation of active oxygen forms (1O2, HO−, НО2−˙and O2−˙) upon excitation with monochromatic light which causes the death of the tumor [10][11][12][13][14]. Some other important features, that photosensitizers should have for such applications are their photo and thermal stability, and an

• thus to affect the photophysical, photochemical and tumor-specific properties of the porphyrin system. Such an approach provides a platform to new photosensitizers with optimized characteristics useful for biomedical applications including PDT. Currently a number of investigations directed for the

Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical complex

• Yoichi Kobayashi,
• Yukie Mamiya,
• Katsuya Mutoh,
• Hikaru Sotome,
• Masafumi Koga,
• Hiroshi Miyasaka and
• Jiro Abe

Beilstein J. Org. Chem. 2019, 15, 2369–2379, doi:10.3762/bjoc.15.229

• of the photochromic reactions to visible light are to extend the π-conjugation and to utilize photosensitizers. Especially, triplet photosensitizers, which form the triplet state of a molecule by the triplet–triplet energy transfer, have been frequently used in photoresists, photodynamic therapy, and

• of hexaarylbiimidazole (HABI), which is a well-known radical-dissociation-type photochromic molecule [17][18][19][20], is not sensitized by triplet photosensitizers [21][22][23]. On the other hand, it was reported that singlet photosensitizers effectively sensitize the photochromic reaction of HABI

• to the visible light [21][23]. While the S0–S1 transition of HABI is located at the visible-light region, the transition is optically forbidden. Therefore, the photochromic reaction of HABI without singlet photosensitizers occurs via the S0–Sn transition, which is located at the UV region. On the

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• . Indeed, photodynamic therapy is used in oncology for the treatment of certain types of tumors. It is based on the activation by light of photosensitizers, able to generate singlet oxygen and/or other reactive oxygen species (ROS), to induce the destruction of the targeted tissues [66]. The dendrimer

Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• two acremine units through a dioxysilane (Scheme 6) [24][25][26]. Unfortunately, irradiation of 25 with and without the presence of different photosensitizers only led to decomposition. Conclusion In conclusion, we report the first asymmetric synthesis of acremine F (5) relying on the combination of a

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• were computed by density functional theory modelling (DFT) and characterized through UV–vis spectroscopy and cyclic voltammetry (CV) measurements. Finally, we report preliminary results obtained using these functional dyes as photosensitizers in dye-sensitized solar cells (DSSCs). Keywords: boron

• liquids are employed [4][5]. Besides, this technology enables the fabrication of solar panels that can be prepared semi-transparent, colorful, and out of non-toxic constituents [6]. Historically, Ru(II)–polypyridyl complexes were the most used dyes as photosensitizers in DSSCs (N719 or N749 Black Dye) [7

• application in DSSCs, in rather good agreement with the values obtained from DFT calculations. Finally, we report preliminary results employing these molecules as photosensitizers in dye solar cells with iodine-based liquid electrolytes. We show that the limited performances of these new BODIPY derivatives

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• photoactivity of photosensitizers (PSs) were annihilated by the complexation of guanidinium-modified calix[5]arene pentadodecyl ether while reactivated by adenosine triphosphate (a cancer biomarker) displacement. This novel supramolecular phototheranostics strategy realized both tumor-selective imaging and

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• photosensitizers [45] to the B12. In this review, we summarize the biomimetic and bioinspired catalytic reactions with B12 enzyme functions, with a focus on our recent work on electrochemical and photochemical systems. 2. 1,2-Migrations of functional groups Enzymes using radical species are models of good

• 1 by replacing reductases with semiconductor photosensitizers and molecular photosensitizers. For example, we reported an ultraviolet-light-driven system using titanium dioxide (TiO2) semiconductor [95][96][97][98][99][100][101]. The conductive band electron of TiO2 (Ered = −0.5 V vs NHE in neutral

• the presence of photosensitizers. 1,2-Migration of a phenyl group mediated by the visible-light-driven catalytic system composed of 1 and Irdfppy. Ring-expansion reactions mediated by the B12-TiO2 hybrid catalyst with UV-light irradiation. Trifluoromethylation and perfluoroalkylation of aromatic

Synthesis and spectroscopic properties of β-meso directly linked porphyrin–corrole hybrid compounds

• Baris Temelli and
• Hilal Kalkan

Beilstein J. Org. Chem. 2018, 14, 187–193, doi:10.3762/bjoc.14.13

• have been focused on the synthesis of multichromophore containing compounds and their potential applications in molecular wires, sensors, nonlinear optical devices, photosensitizers and organic conducting materials [3][4][5][6]. The first studies on the synthesis of multichromophores were based on

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• vesicles could also be linked to an internal chemical reaction. In this case [101], the irradiation of membrane-located photosensitizers stimulated the formation of disulfide bonds in small hydrophilic molecules in the vesicle lumen, which then migrated subsequently into the boundaries provoking changes in

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• aqueous medium, which precludes any response to light excitation. Keywords: β-cyclodextrins; fluorescence; photodynamic therapy; photosensitizers; singlet oxygen; xanthene; Introduction Cyclodextrins (CDs) are cyclic oligosaccharides able to form host–guest inclusion complexes with drugs and this

• results we decided to use this method for the coupling with xanthene dyes which upon light irradiation are able to generate cytotoxic 1O2. The coupled products would thus represent a new family of photosensitizers, the eosin-CDs (Eo–CDs). Although the photobactericidal activity of Eo dyes is well known

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• scattering and absorption by tissue is minimized and a more in-depth therapy becomes possible. The search for more effective compounds with absorption in the near infrared includes amongst others cyanine [10], bodipy [11], and phthalocyanine [12] photosensitizers and has lately led to the consideration of a

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• especially evident from a consideration of the extent of light attenuation when passing through condensed matter. The molar attenuation coefficients of common organic photosensitizers are in the range of 20,000–500,000 M−1 cm−1 (Table 1) which significantly limits the penetration depth of visible light into

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• drugs for medical applications [18][19]. In fact, for pharmaceutical applications, the improvement of drug stability and solubility play a key role [19]. For example, CDs emerged in biological applications as suitable delivery systems for water-insoluble photosensitizers (PSs) for light-induced

Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

• Giuseppina Raffaini,
• Antonino Mazzaglia and
• Fabio Ganazzoli

Beilstein J. Org. Chem. 2015, 11, 2459–2473, doi:10.3762/bjoc.11.267

• recently reported [14], while analogue cationic aCD with terminal short amino-PEG at the secondary rim form nanoassemblies which entrap photosensitizers for photoactivated therapy [25] or DNA for gene delivery [26][27][28][29][30]. The potential of aCD is strengthened by their ability to selectively

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• reported the successful synthesis of 64Cu-chelated porphyrin photosensitizers and a tumor targeting peptide. To the best of our knowledge, no previous example of the preparation of radioligand 64Cu corrole has been so far reported. Due to their easy copper insertion [21], corroles can be considered as

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• photoelectric materials [7][8]. In addition, porphyrins are potentially used as photosensitizers in photodynamic therapy to treat various types of tumors [9][10]. In recent years, many hybrid molecules including porphyrin–C60 [11], porphyrin–quinones [12] and porphyrin–cyclodextrin [13] conjugates were

• xanthones, it was contemplated to incorporate these heterocyclic scaffolds in a single molecular framework to construct novel β-triazolo–porphyrin–xanthone conjugates and their diporphyrin analogues which may prove useful as photosensitizers for photodynamic therapy applications. Results and Discussion In

• bathochromic shift in their electronic absorption and fluorescence spectra as compared to the meso-tetraarylporphyrins. These results are significantly encouraging and henceforth may be useful for the development of new porphyrin materials for various applications including photosensitizers for photodynamic

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• (EPFL), Station 6, CH-1050 Lausanne, Switzerland 10.3762/bjoc.11.118 Abstract Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A) and a hybrid electron donor (D) of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were

• ][8] have been used in the construction of photosensitizers. Not surprisingly, tetrathiafulvalene (TTF), as a strong π-electron donor, has been incorporated into different D–π–A systems for numerous potential applications [9][10][11][12][13][14]. However, TTF-sensitized solar cells have rarely been

• substantial charge recombination losses during the electron-injection process, very probably caused by self-aggregation on the TiO2 surface and fast back-electron transfer upon photoexcitation. Conclusion In summary, we have synthesized two new organic photosensitizers featured with a DTF–CPDT hybrid as an