Polymer chemistry: fundamentals and applications

• Bernhard V. K. J. Schmidt

Beilstein J. Org. Chem. 2021, 17, 2922–2923, doi:10.3762/bjoc.17.200

• materials [6]. This thematic issue covers a broad range of current topics in polymer chemistry, from synthesis to materials and applications. In the area of synthetic methods, the use of click photochemistry in polymer and organic molecule synthesis is presented, as well as the combination of polymers with

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• emitter in vacuum-deposited films, which occurs only at the surface of the film where the emitter orientation is then “frozen” into place once additional layers of material have covered it. While this loss of controlled orientation in the solution-processed film is true for small molecules, polymers and

• other high molecular weight emitters can show at least some degree of orientation in solution-processed films. For instance, Senes et al. [23][24]. showed that the OPVn series of polymers exhibited higher horizontal orientation by increasing the length of the polymer chain, and by extension the molecule

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• -catalyzed enantioselective transformations [9][14][22][23]. Axial chirality is also found in chiral stationary phases for enantioselective separation, dopants in liquid-crystalline materials, chiroptical molecular switches, microporous soluble polymers, and interlocked nanotubes (Figure 3) [24]. In addition

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• electronic and optical properties [16][17][18][19][20][21], utilized in LEDs, semiconducting polymers, and solar cells. Consequently, synthetic approaches to fluorenones have attracted large interest and numerous methodologically diverse approaches have been published in the past decades. Among these are

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• established, commercial polymers in solution [17]. We recently reported the self-assembly of polyethylene oxide (PEO) polymers into cylindrical nanostructures, also called supramolecular polymer bottlebrushes (SPBs), based on the end group modification with hydrogen bond forming benzenetrisurea (BTU) and

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

• Luke O. Jones Leah Williams Tasmin Boam Martin Kalmet Chidubem Oguike Fiona L. Hatton Department of Materials, Loughborough University, Loughborough, LE11 3TU, UK 10.3762/bjoc.17.171 Abstract Cryogels are macroporous polymeric structures formed from the cryogelation of monomers/polymers in a

• . Common cryogel compositions include natural polymers such as gelatin and chitosan, and synthetic acrylamide-based polymers and poly(vinyl alcohol) (PVA) [12][13][14]. The reader is directed to a recent review by Thakor and co-workers which discusses cryogel synthesis in greater depth [15]. 2. Cryogel

• polymer selection. For example, altering the ratio of hydrophobic and hydrophilic polymers in the final cryogel structure can allow for fine tuning of the responsive behaviour [33][34]. At specific and unique temperatures, phase changes occur to a temperature-responsive polymer, physically changing the

In-depth characterization of self-healing polymers based on π–π interactions

• Josefine Meurer,
• Julian Hniopek,
• Johannes Ahner,
• Michael Schmitt,
• Jürgen Popp,
• Stefan Zechel,
• Kalina Peneva and
• Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

• of Photonic Technology (IPHT), e. V. Jena, Albert-Einstein-Straße 9, 07745 Jena, Germany 10.3762/bjoc.17.166 Abstract The self-healing behavior of two supramolecular polymers based on π–π-interactions featuring different polymer backbones is presented. For this purpose, these polymers were

• synthesized utilizing a polycondensation of a perylene tetracarboxylic dianhydride with polyether-based diamines and the resulting materials were investigated using various analytical techniques. Thus, the molecular structure of the polymers could be correlated with the ability for self-healing. Moreover, the

• behavior was also quantified in detail using an indenter. Keywords: characterization of polymers; π–π-interactions; self-healing polymers; supramolecular polymers; Introduction Damage inflicted on different materials is omnipresent. Consequently, nature established a mechanism dealing with this problem

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

• azide derivatives under both white LED and NIR light irradiation. Due to its deeper penetration of NIR light, the possibility of synthesizing different macromolecular structures such as functional polymers, cross-linked networks and block copolymer has also been demonstrated. The structural and

• [40]. BPNs were tested as NIR photoinitiator for the CuAAC reactions of low molar mass compounds and polymers possessing antagonist azide and alkyne functionalities (Figure 1). The optical absorption spectra of BPNs, copper(I) chloride (CuICl, 0.05 mmol) and copper(II) chloride (CuIICl2, 0.05 mmol

• clearly confirmed the successful chain-end functionalization. In addition, block copolymer formation via NIR activated CuAAC process between the polymers having antagonist click components, namely, polystyrene azide (PS-Az) and PCL-Alk, was investigated. At the end of irradiation in the presence of

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• hand, carbazole derivatives also have potential applications in optoelectronic materials, conducting polymers, and synthetic dyes [9][10][11]. Over the past decades, many efficient synthetic methodologies for functionalized carbazole derivatives have been successfully developed [12][13][14][15][16][17

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• be taken into account that the drug can interfere with the block copolymer aggregation. Alternatively, the use of reactive polymers for the polymerization creates a functional anchor to enable post-functionalization of the PISA nanoparticles with drugs such as doxorubicin [35][36]. In a different

• repel proteins and therefore reduce the possibility of macrophage clearance [41]. Therefore, in this study we will use poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) and poly(oligo ethylene glycol methyl ether methacrylate) (pPEGMA) as protein-repellent polymers in order to ensure that the

• the self-assembly process [43]. Moreover, a second nanoparticle based on poly(oligo ethylene glycol methyl ether methacrylate) (pPEGMA) was generated as both polymers, pPEGMA and pMPC display protein-repellent properties [44][45]. In this paper, we aimed at comparing the effect of nanoparticles with

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

• , anti-Kasha photophysics, and a small HOMO–LUMO gap when compared to its isomer, naphthalene. These properties make azulene-containing polymers an intriguing entity in the field of functional polymers, especially for organic electronic applications like organic field-effect transistors (OFET) and

• photovoltaic (PV) cells. Since azulene has a fused five and seven-membered ring structure, it can be incorporated onto the polymer backbone through either of these rings or by involving both the rings. These azulene-connection patterns can influence the properties of the resulting polymers and the chemical

• synthesis of functional polymers is also an interesting proposition and such polymers can find promising applications in the organic electronics field such as organic field-effect transistors (OFET) and photovoltaic (PV) cells [15][16]. The synthesis of azulene-containing polymers can be envisaged through

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

• the last decades, numerous stimuli-responsive polymers have been developed and investigated regarding their switching properties. In particular, thermoresponsive polymers, which form a miscibility gap with the ambient solvent with a lower or upper critical demixing point depending on the temperature

• , have been intensively studied in solution. For the application of such polymers in novel sensors, drug delivery systems or as multifunctional coatings, they typically have to be transferred into specific arrangements, such as micelles, polymer films or grafted nanoparticles. However, it turns out that

• the thermodynamic concept for the phase transition of free polymer chains fails, when thermoresponsive polymers are assembled into such sterically confined architectures. Whereas many published studies focus on synthetic aspects as well as individual applications of thermoresponsive polymers, the

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

• non-conductive polymers like water-soluble poly(2-ethyl-2-oxazoline) (PEtOx) [35], polypropylene (PP) [36][37] photo-cross-linkable and biodegradable poly(ʟ-lactide-co-ε-caprolactone-co-acryloyl carbonate) [38], or thermoplastic elastomers [39] have successfully been processed via MEW [40

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

• 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

• polymerization upon exposure to the laser diode at 785 nm was successfully initiated using new synthesized dyes. This can be used to obtain tack-free polymers after only a few seconds of NIR irradiation. Markedly, IPNs can also be prepared with NIR light. Potential applications and investigations of the

• mechanical properties of the generated polymers and composites will be provided in the forthcoming works. Visible–NIR spectra of NIR dyes in ACN. A) (1) CBPh1, (2) CBPh2, (3) CBPh3, (4) CBPh4, (5) Ca, (6) Cb, and (7) CNa. B) (1) CI1, (2) CI2, (3) CI3, (4) CI4, (5) CI5, (6) CI6, (7) CI7, (8) CI8, (9) CI9, and

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• polysaccharides. For each class of polysaccharides, we discuss the available synthetic approaches and their current limitations. Keywords: enzymes; glycans; polysaccharides; synthesis; well-defined polymers; Introduction Polysaccharides are an abundant class of natural polymers that play important roles in the

• only small modifications, hampering the formation of unnatural polymers. Low glycosylation yields and product hydrolysis represent additional hurdles associated with enzymatic synthesis of polysaccharides [23]. With this approach, homopolymers are often obtained as non-uniform samples, because the

• polysaccharides longer than hexasaccharides. Shorter oligomers are discussed when they represent a key step towards the synthesis of the corresponding polysaccharide. Polymers based on a sugar backbone connected via glycosidic linkages are analyzed, excluding glycopolymers and other mimetics. Extraction

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• -melanin Melanins are a heterogenous group of hydrophobic phenolic polymers that are found in a range of organisms including bacteria, plants, fungi and even animals. The melanin pigments are of mostly dark colours like black or brown and are associated with virulence in plant- and animal-pathogenic fungi

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• stability of the phosphines was also evaluated and the most electron-rich TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar

• the reaction time to 24 h led to high double-bond conversion of 89% in case of TPP and 97% and 99% in the cases of MMTPP and TMTPP. Molar mass distributions of the polymers prepared with a reaction time of 24 h were determined by SEC. First, the polymerizations conducted at room temperature are

• 13C NMR spectrum of poly4 (see Supporting Information File 1) and its share is with approximately 17–20% higher in polymers prepared at 80 °C (Figure 2). The formation of this repeat unit consumes two equivalents of acrylates and thus, disproportionally decreases the quantity of acrylate groups in

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• photoelectrochemical reduction of water, as matrix for MALDI spectrometry and in photothermal cancer therapy are also shown. Data published over the past 5 years, including works published at the beginning of 2021, are given. Keywords: isoindigo; OFET; photoactive polymers; photovoltaics; solar cells; Introduction

• the morphology of thin films of the photovoltaic cells. To date, the maximum efficiency of 12.05% has been shown by an OSC based on a composite of a donor polythiophene and an acceptor polymeric dicyanoindanone derivative [13]. Among the derivatives of isoindigo, the leading compounds are polymers 1–3

• popular and most studied direction in the creation of OSCs is the use of polymer structures containing an isoindigo fragment in a monomer unit associated with a different number of thiophene substituents (Scheme 12). By the example of one of the simplest representatives of this type of polymers, a

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

• Cansu Esen Baris Kumru Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany 10.3762/bjoc.17.92 Abstract Hydrogels are a special class of crosslinked hydrophilic polymers with a high water content through their porous structures

• systems as a representative synthetic approach to modulate porous structures of hydrogels with secondary polymers via visible-light-induced reaction. The photoactivity of g-CN materials are attractive in this sense since covalent modification of the surface of g-CN has offered a versatile post

• pore structures based on the type of the interpenetrated polymer. While PAA and PEGMEMA formations mostly bound intrinsically surface-attached, PAAM exhibited comb-like strands by connecting two junction points on the substrate. The reason of this might be both topological selectivity of polymers and

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• glycerol α-chlorohydrin, the ratio of I/II was 1:4 with II being the preferred isomer but when using glycidol, this ratio shifted to 3:1 in the favor of the desired isomer [96][97]. From there on, the use of glycidol for the preparation of GNA analogues became the gold standard. The first GNA polymers were

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• study the complexing properties of new fullerene derivatives. An interesting approach was developed [95] for the synthesis of diphenyl-substituted fulleroids 40 and 41 as a two-section precursor of “pearl necklace” polymers with a C60 core in the main chain (Figure 5). However, the adducts were poorly

• soluble in the majority of organic solvents and only partially soluble in carbon disulfide, which is expected to ultimately lead to similar insoluble hard-to-recover polymers. It is believed [95] that the best solution to the problem seems to involve the incorporation of solubilizing groups into the

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• usually synthetic polymers recalcitrant to decomposition, and hence liable to accumulate in landfills or the environment when discarded [5][6]. Not all plastics can be reused, and thus having limited economic value [7][8]. Plastics may release toxic compounds dangerous to human health and the habitat [9

• turn a challenge into an opportunity [24][25]. The waste-to-products strategy is already in place for both animal [26][27] and plant biomass polymeric waste [28][29], for which mature technologies are operative [30]. When referring to polymers in general, there is often a lack of univocal definitions

• to the action of chemical (acids, air, halogens, solvents) or physical agents (heat, light). For polymers, the properties involved are, for instance, tensile strength, colour or shape, the change of which is usually associated with a modification of the chemical composition (e.g., as a consequence of

Synthesis of N-perfluoroalkyl-3,4-disubstituted pyrroles by rhodium-catalyzed transannulation of N-fluoroalkyl-1,2,3-triazoles with terminal alkynes

• Olga Bakhanovich,
• Viktor Khutorianskyi,
• Vladimir Motornov and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 504–510, doi:10.3762/bjoc.17.44

• , agrochemicals, and functional materials (polymers, dyes, films, etc.) (Figure 1) [1][2][3][4]. Numerous methods exist for pyrrole synthesis, including the classical and industrially important condensation approaches, such as the Hantzsch, Huisgen, and Paal–Knorr processes [5]. However, the direct modification

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

• polymers. A possibility for spin density delocalization across o-quinone and annulated moieties, found by EPR spectroscopy study of their monoreduced derivatives, is a confirmation for the hypothesis that such ditopic ligands could provide an effective channel for electronic exchange interactions between

• useful in the design of coordination polymers. A stable o-quinone derivative containing an annulated thiete ring was isolated and characterized. The use of these new ligands for the preparation of binuclear complexes or coordination polymers seems to be interesting from the viewpoint of construction of