Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• particularly innovative is its ability to operate in the presence of oxygen, overcoming a common limitation in radical polymerization, and its demonstrated efficacy in penetrating biological tissues up to 7 mm thick. Beyond the phthalocyanin/porphyrin family, other kinds of traditional organic photocatalysts

• same team further proposed various infrared-mediated reactions catalyzed by 40 as presented in Figure 7. It has to be noted that other squaraine derivatives have also been explored as innovative photoinitiators and photosensitizers for initiating the free radical polymerization (FRP) of methacrylates

• processes. Cyanins have been shown to effectively initiate radical polymerization under visible light through mechanisms such as borate oxidation [61] and 1,3,5-triazine reduction [62]. More recently, cyanin dyes have enabled the reduction of iodonium salts under NIR excitation [63][64]. These preliminary

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• units are easily modified by acylation, the hydrophilicity of the rotaxane crosslinker (RC) could be tuned in this manner. This [3]rotaxane crosslinker RC was added 0.5 mol % on the standard free radical polymerization of vinyl monomers to afford rotaxane-crosslinked polymer (RCP) (Figure 15B). Similar

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• adapted with permission of Institution of Chemical Engineers (IChemE) and The Royal Society of Chemistry from [38] (“Cationic and radical polymerization using a boron–thienothiophene–triphenylamine based D-π-A type photosensitizer under white LED irradiation”) by A. Suerkan et al., Mol. Syst. Des. Eng

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• past century, new knowledge on radical chemistry has both promoted and been generated from the emergence of polymer synthesis and modification techniques. In this review, we discuss radical chemistry in polymer science from four interconnected aspects. We begin with radical polymerization, the most

• chemistry found in polymer science. Section 1 focuses on the best-established radical chemistry – radical polymerization, including radical polymerization in nature, conventional radical polymerization, and a new class of radical polymerization, reversible deactivation radical polymerization, which emerged

• radical degradation of polymers, both in nanofabrication and polymer upcycling. Review 1 Radical polymerization Radical polymerization has long been an effective and inexpensive method in the synthesis of polymers since it was invented, making it the most important industrial polymerization technique

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• in the formation of H2 and O2 from the water splitting reaction by donating strain-induced electrons and holes [53]. The piezoelectricity obtained upon ultrasonication of BaTiO3 has also been used to trigger and sustain atom transfer radical polymerization (ATRP) reactions of acrylate monomers by

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• chilled tube containing PRP (1), appeared to undergo free-radical polymerization when increasing the temperature to 25 °C. Despite this failed experiment, in general, PRP (1) has established itself as a highly reactive 1,3-dipole towards cyclopropene dipolarophiles 2. In this study, we did not confine

A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

• Yuki Yamamoto,
• Akihiro Tabuchi,
• Kazumi Hosono,
• Takanori Ochi,
• Kento Yamazaki,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 2906–2914, doi:10.3762/bjoc.17.198

• the α-position relative to the carbonyl group, is the most versatile synthetic intermediate [19][20][21][22][23][24][25][26][27][28]. α-Bromolactones are widely used as synthetic intermediates for functional materials and pharmaceuticals, as well as initiators in atom-transfer living radical

• polymerization (ATRP) reactions and functional polymer synthesis [29][30][31][32][33][34]. Although α-bromo-γ-butyrolactone, which is a five-membered lactone, is easily accessible from the five-membered lactone by some bromination methods [35][36], the bromination method for the six-membered lactone, δ

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• photocatalysts have been successfully applied in both small- and large-scale synthesis such as organic reactions [16][17], free radical polymerization (FRP) [18][19][20], controlled radical polymerization (CRP) [21][22], CuAAC chemistry [23][24][25], and thiol–ene chemistry [26][27]. However, most of the

• [34][38][39][40]. The use of 2D materials for the photoinitiated electron transfer reactions with CuII catalysts for the photoinduced atom transfer radical polymerization (ATRP) and CuAAC reactions prompted us to develop a new photoredox system that works under NIR irradiation for the CuAAC reaction

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• contrast. Azulene-methacrylate copolymers Emrick and co-workers [45] reported the synthesis of azulene-substituted methacrylate polymers derived from a free radical polymerization strategy, where azulenes were used as pendants. The key starting points to make these polymers were azulene-2-yl methacrylate

• free radical polymerization by using azobis(isobutyronitrile) (AIBN) to obtain the polymers 151 and 152 in 73 and 82% yields, respectively (Scheme 26A and B). The Mn and PDI for these polymers 151 and 152 were 13500 Da, 2.5 and 13600 Da, 2.2, respectively, and their solubility was good in organic

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone)

• Jochen Löblein,
• Thomas Lorson,
• Miriam Komma,
• Tobias Kielholz,
• Maike Windbergs,
• Paul D. Dalton and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2021, 17, 2095–2101, doi:10.3762/bjoc.17.136

• demonstrate this surface modification using a hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA) [19]. However, this approach should have broad utility for a spectrum of monomers and macromonomers susceptible to radical polymerization onto (almost) any surface featuring C–H bonds. This hydrogel coating is

• scaffolds, which may be required for suitable interaction with cells or other materials. SIPGP does not require special equipment other than a UV lamp or special reagents. As a proof-of-concept, we demonstrated the feasibility using HEMA as monomer, but essentially any monomer polymerizable by free radical

• polymerization should be feasible. At this point, the coating of the fibrous scaffolds is rather inhomogeneous, as the surface-initiated polymerization is confounded by polymerization in bulk. Therefore, we are currently working on a slightly modified experimental setup, which utilizes a flow setup, constantly

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• combination with an amine and an iodonium salt, iod, for the free radical polymerization of a benchmark acrylate monomer and compared to a reference initiating system based on IR 813 (Scheme 2) [7]. As the different dyes presented above exhibit good absorption properties at 785 nm, the photoinitiating

• depicted in Figure 2 and Figure 3. The NIR dyes proposed have strong abilities to initiate the free radical polymerization. Indeed, the polymers obtained are tack-free after only a few seconds of irradiation (Scheme 6). Without NIR dyes, no polymerization occurs. At 785 nm, in most cases, the final

• mechanical properties or lower shrinkage than pure radical polymerization. Conclusion In the present study, a number of NIR-absorbing dyes has been investigated as potential NIR PISs. The NIR curing of acrylate monomer is proposed in the presence of three-component PISs (NIR dye/iod/amine). The free radical

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• , ascorbic acid/hydrogen peroxide, respectively. The mixture was immediately placed in a Petri dish to complete the gelation via free radical polymerization under dark conditions. After 3 hours, the resulting hydrogel was purified with water to remove the unreacted species (monomers and redox mediators

• modification platform [49]. The as-prepared hydrogel network (HGCM) was immersed in various acrylic monomers. Following that, photoinduced free radical polymerization of employed monomers performed under visible light irradiation by taking advantage of embedded g-CN nanosheets in HGCM. According to literature

• ). After the polymerization was completed, polymer networks were purified as delineated in the experimental section. Altered pore morphology was investigated by SEM, and functional group analysis was achieved by FTIR. Enrichment of the hydrogel network with subsequent radical polymerization using various

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• electroactive materials [52][53][54]. Carbazole-based [6]helicenes [42] and [7]helicenes [50] showed deep blue electroluminescence and have been investigated in OLED devices. Some carbazole-based [5]- and [6]helicenes have been used as visible light photoinitiators for cationic and radical polymerization [41

Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256

• recently, it has been shown that some of these common amine–borane complexes can also be used as radical initiators for atom transfer radical addition of alkyl halides to alkenes [48]. They were also used in the free-radical polymerization of alkene-containing monomers such as methyl methacrylate or

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

• two different types of free radical intermediates, 30 and 31 (Scheme 8). The species 31 was shown to be the primary initiating radical compound. In 2006, Aydin and Arsu employed benzaldehyde (8) as the coinitiator for the photoinitiated free radical polymerization of multifunctional MMA (26) [38

• prefer to abstract a hydrogen atom from a ketone/aldehyde monomer molecule rather than to decompose, forming a monomeric radical, which can initiate the polymerization. In 2017, Ma and co-workers performed a photoinduced controlled radical polymerization of methacrylates using perfluoro-1-iodohexane (50

• (50), generating a benzaldehyde radical cation (56) and the radical of the alkyl group C6F13, 58, which was proposed to initiate the radical polymerization of a methacrylate monomer 59. N,N-Dimethylaniline (51) acted as the reducing agent, regenerating the ground state of the benzaldehyde catalysts 52

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

• = −0.64 V [5][84]) or the triazine 89 (Ered = −0.77 V [5]) carrying no charge as acceptor (Scheme 5). Thus, the positive charge of the iodonium cation is likely not the reason because 89 exhibits no charge. Both possess similar reduction potentials but the efficiency to initiate radical polymerization was

• been in progress. Tailor-made synthesis by photo-ATRP with NIR sensitizers NIR absorbers/sensitizers have also reached the field of polymer synthesis; that is controlled/living radical polymerization (CLRP). This facilitates well-defined polymeric materials with pre-design architectures, predetermined

• molar masses and narrow molecular weight distributions. These techniques allow linear increase of molar mass by time and monomer conversion and low dispersity (principally between 1.2 to 1.5). The most common methods of controlled radical polymerization are namely the nitroxide-mediated radical

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• multiblock copolymers with respect to self-assembly. In recent years, it was demonstrated that such polymers can be prepared with many of the available techniques, including polycondensation [28], chain-shuttling polymerization [29], copper-mediated radical polymerization [30][31][32], reversible addition

• exclusive trans regularity and contained vinyl groups at the both polymer chain ends. These groups were treated with a Mo catalyst to generate the corresponding Mo-alkylidene moieties followed by the Wittig-type cleavage with various aldehydes, gave an opportunity to utilize atom transfer radical

• polymerization (ATRP) and сlick reactions for the precise synthesis of amphiphilic ABCBA-type block copolymers (Scheme 4) [63]. A more facile “one-pot” procedure for the synthesis of an end-functionalized conjugated multiblock copolymer with PFV main chain was accomplished by combining olefin metathesis and

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• the case of a d5 high spin octahedral complex in Figure 4. As for LMCT, MLCT give intense band in UV spectrum. 1.4 Mechanisms in polymerization reactions Free radical polymerization or/and cationic polymerization can be initiated by photoredox catalysis. Respectively, radicals or/and cations must be

• industrial fields. About 45% of the manufactured plastic material and 40% of synthetic rubber are produced by free radical polymerization worldwide [23]. In both cases, the photoredox catalyst, used as PS, absorbs the light and goes to its excited state. Then, there are two possibilities: the photoredox

• , formations of interpenetrated polymer networks (IPN) are also mentioned. For the three systems proposed above, formation of aryl radicals is observed. These radicals are able to initiate the free radical polymerization of (meth)acrylates [1]. In the photocatalytic cycle (Figure 5C), EDB(−H)• radicals are

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

• Paweł Chmielarz,
• Tomasz Pacześniak,
• Katarzyna Rydel-Ciszek,
• Izabela Zaborniak,
• Paulina Biedka and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2017, 13, 2466–2472, doi:10.3762/bjoc.13.243

• ; quercetin-based macromolecules; Introduction In the last decade, there have been increasing research activities in the use of atom transfer radical polymerization (ATRP) to prepare naturally-derived star-like polymers [1][2][3][4]. Considering this method, naturally-occurring polymers can be synthesized

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• Sadaf Hanif Bernd Oschmann Dmitri Spetter Muhammad Nawaz Tahir Wolfgang Tremel Rudolf Zentel Institute for Organic Chemistry, University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany 10.3762/bjoc.13.163 Abstract This paper describes the controlled radical polymerization of an ionic-liquid

• are applied as catalytic membranes, thermotropic liquid crystals [12], polymer electrolytes, ionic conductive materials, CO2 absorbing materials, microwave absorbing materials and porous materials [4]. Most of these polymers were synthesized by free radical polymerization. There are just few reports

• about controlled/living radical polymerization, like nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain transfer polymerization (RAFT) [2]. In general, by controlled radical polymerization techniques it is possible to prepare

One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• other polymerization techniques, such as atom transfer radical polymerization, because of the lack of toxic metal additives, and because of good control exerted in aqueous solution. The water-soluble bifunctional CTA S,S′-bis(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate (DMATC) was selected because it

• degree of polymerization Pw of the polymer backbone according to the values of Pw were in reasonable agreement with the molar ratio of the related monomer vs CTA (175), which was indicative for a significant control of the radical polymerization by the CTA. The observed polydispersity indices Mw/Mn

Kinetic analysis of mechanoradical formation during the mechanolysis of dextran and glycogen

• Naoki Doi,
• Yasushi Sasai,
• Yukinori Yamauchi,
• Tetsuo Adachi,
• Masayuki Kuzuya and
• Shin-ichi Kondo

Beilstein J. Org. Chem. 2017, 13, 1174–1183, doi:10.3762/bjoc.13.116

• initiation, γ-irradiation) from hydroxy groups [11][12][13][14]. However, as the polysaccharide backbone is unstable under these harsh and high temperature conditions, these compounds are not suitable for condensation polymerizations to synthesize graft copolymers [15]. In general a radical polymerization

Cyclodextrins tethered with oligolactides – green synthesis and structural assessment

• Cristian Peptu,
• Mihaela Balan-Porcarasu,
• Alena Šišková,
• Ľudovít Škultéty and
• Jaroslav Mosnáček

Beilstein J. Org. Chem. 2017, 13, 779–792, doi:10.3762/bjoc.13.77

• available as commercial products, the modification with polymers is still under development [4][5]. So far, several polymerization reactions were used for CD modification, including free radical polymerization, reversible-deactivation radical polymerizations [5] as well as ring opening polymerizations (ROP

Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

• Maximilian Maier,
• Magnus S. Schmidt,
• Markus Ringwald and
• Christoph P. Fik

Beilstein J. Org. Chem. 2017, 13, 372–383, doi:10.3762/bjoc.13.40

• ; Introduction The selection of suitable monomers is a critical step for any free-radical polymerization approach. Particularly for (in situ) photo-induced polymerizations, monomers should comprise sufficient solubility in a given matrix, moderate viscosity, matching refractive indices as well as an optimized

• ]. Yet, acrylamides are particularly affected by the solvent regarding propagation reaction in free radical polymerization, even more so, if water is present [21]. Factors such as hydrogen bonding, hydrogen abstraction and the overall electronic characteristics are crucial in the design of improved

• has been realized. When allyl- and acrylamide functionalities were spatially adjacent, a “synergistic potential” beneficial in radical polymerization was expected (Scheme 1). Synthesis Six derivatives of highly functionalized crosslinkers 1–6 were synthesized as outlined in Scheme 2. We started from