Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

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

• tasks due to their adaptability and physical-chemical properties [18]. Macroporous polymeric gels with their unique heterogeneous open-porous structure open new perspectives for the development of innovative systems for biomedical and pharmaceutical applications. Cryotropic gelation is an efficient

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

• -hydroxypropan-1-ol) ether (Az-3), and 1-(prop-2-yn-1-yloxy)-2,2-bis((prop-2-yn-1-yloxy)methyl)butane (Alk-5) as multifunctional click components were irradiated in the presence of BPNs and CuII ligand under NIR light. The gelation was completed after 24 h (Scheme 3). The photocuring process was also followed by

• (0.1 equiv) in a small transparent vial and 300 µL BPNs in DMF was added to the vial, then irradiated 4 h. After the gelation was completed, the gel was placed in DCM for 24 h hours, then filtered and dried 24 h in a vacuum oven. Structures of azide and alkyne functional molecules and polymers used in

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

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

• capped and left for 3 hours to obtain a gelation via redox-induced free radical polymerization. Afterwards, it was washed with distilled water to remove the unreacted species and freeze dried for 24 hours. The resulting light and brittle g-CN nanosheets embedded hydrogel was ready for further usage. In

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• photodimerization [55][56][57], photocleavage [58][59], and cis–trans photoisomerization [60][61][62][63][64][65]. While it had been well-established to access oligomer formation and gelation, a light-switchable particle size has remained a challenge until realized through the mentioned electrostatic self-assembly

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• -gel was about three times higher than the glum values of R2N-TBPP and S2N-TBPP enantiomers. Interestingly, the CPL handedness of the rac-TBPP/DGG co-gel could be adjusted effectively by changing their stoichiometric ratios. Keywords: circularly polarized luminescence; chiral resolution; co-gelation

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• that the formation of a gel structure was observed for concentrations as low as 0.5 wt %. Organogelators that are able to gel solvents at concentrations at <1% are classified as supergelators [29][30][31]. Furthermore, the results from the solubility tests where the ability of gelation decreases with

• demonstrate the thermal reversibility of the gelation process. There are peak maxima at the heating and cooling phases that can be assigned to the formation of the gel structure and its decomposition. For the heating phase, a maximum was found at 45 °C, the endothermic melting process of the sample. In the

• micelles. At elevated temperatures these interactions are weakened. Thus, the RWLM can move freely within the solvent and the material becomes fluid. Conclusion In summary, we could show that the gelation of nonpolar solvents by dirhamnolipid esters is caused by the formation of branched RWLM. These

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• stabilization of the supramolecular aggregation of bis(4-bromophenyl)triazoles. The trans or cis spatial disposition of the triazole rings is highly important for gelation, with the cis configuration having higher propensity. Keywords: circular dichroism; cis/trans configuration; gels; triazole; X-ray

• low-molecular-weight gelators have potential applications in high-tech materials [1][2][3] and biomedical sciences [3][4][5][6]. Triazole derivatives have shown excellent gelation properties [7][8][9][10], in addition to a broad range of biological activities [11][12][13][14]. During the synthesis and

• (Scheme 2) showed supramolecular features, i.e., their DMSO solutions prepared for NMR analyses spontaneously transformed into gels inside the NMR tubes. Three cis-/trans-configured pairs of compounds were chosen for a gelation ability study. Thus, analogue pairs 8f/7f (Scheme 2), 10/9 (Scheme 3), and 14

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• systems [10][11]. One of the drawbacks of these catalyst systems is the “excessive hardness” of the system viz. HSAB theory leading to the formation of cross-linked structures and gelation of the system. Substitution of chlorine atoms in the catalyst structure with organic ligands allows reducing of the

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• aliphatic chain and on the other side to a glutamic acid residue. The gelator bearing the free carboxylic groups showed a lower gelation capacity than its precursor diester derivative. Some selected gels were further studied by infrared spectroscopy, rheology and electron microscopy. Critical gelation

• concentrations and gel-to-sol transition temperatures were also determined for each case. In addition, the superior squaramide diester gelator was compared with an analogue triazole-based gelator in terms of critical gelation concentration, gelation kinetics and thermal phase transition. Keywords: glutamic acid

• properties of supramolecular gels [33]. Specifically, we exchanged the amide group of N-stearoyl-L-glutamic acid (1, Figure 1), a known LMW gelator [34], by its non-classical isostere [35][36] 1,4-disubstituted 1,2,3-triazole 2 (Figure 1). This approach enabled us to fine-tuning the gelation capacity and the

A self-assembled photoresponsive gel consisting of chiral nanofibers

• Lei Zou,
• Dan Han,
• Zhiyi Yuan,
• Dongdong Chang and
• Xiang Ma

Beilstein J. Org. Chem. 2018, 14, 1994–2001, doi:10.3762/bjoc.14.174

• structure, and the nanostructures of the assembled compound 3 can be adjusted by both solvent and light. The formation of organogels in various solvents was conducted to test the gelation ability of compound 3. The gel was fabricated by melting compound 3 in solution by heating for about 20 min, followed by

• allowing the solution to rest at room temperature for 30 min. The gelation ability of compound 3 in various organic solvents was investigated by using the “stable to inversion of a test tube” method (Figure 5a). Here we arrive at the conclusion that compound 3 can only form an organogel in nonpolar

• aromatic solvents such as benzene and p-xylene. Table 1 lists the solvent parameters and the gel-forming ability of compound 3 in various organic solvents. The critical gelation concentration (CGC) is also noted. We took the gel formed in benzene as the example for the following investigations. The

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• . Another common mistake with a significant impact on further experiments is preparing a too highly concentrated polynucleotide stock solution. Particularly, guanine-rich polynucleotides are prone to gelation and consequently to formation of non-homogeneous solutions. Thus, an optimal concentration for the

Aggregation behaviour of a single-chain, phenylene-modified bolalipid and its miscibility with classical phospholipids

• Simon Drescher,
• Vasil M. Garamus,
• Christopher J. Garvey,
• Annette Meister and
• Alfred Blume

Beilstein J. Org. Chem. 2017, 13, 995–1007, doi:10.3762/bjoc.13.99

• gelation of the suspension when the bolalipid PC-C18pPhC18-PC is dissolved in water at a concentration of c = 1 mg mL–1. This behaviour indicates the formation of nanofibres, which in turn immobilize the solvent molecules and allow the formation of a transparent hydrogel. A similar observation was found

• 50 °C can be connected that in these conditions also some multilamellar objects are formed. Conclusion The PC-C18pPhC18-PC, a long-chain, phenylene-modified bolalipid, self-assembles at room temperature into nanofibres, which leads to a gelation of the suspension. With increasing temperature, the

A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation

• Wangkhem P. Singh and
• Rajkumar S. Singh

Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17

• commonly used protecting group for primary alcohols as a gelling structural component in the design of molecular gelators. We synthesized a small library of triphenylmethyl derivatives of simple primary alcohols and studied their gelation properties in different solvents. Gelation efficiency for some of

• the derivatives was moderate to excellent with a minimum gelation concentration ranging between 0.5–4.0% w/v and a gel–sol transition temperature range of 31–75 °C. 1,8-Bis(trityloxy)octane, the ditrityl derivative of 1,8-octanediol was the most efficient organogelator. Detailed characterizations of

• molecular scaffolds and tested for their gelation abilities. In another approach, modifications are made to known gelator scaffolds in the search for new gelators. These approaches have been used widely with a fair degree of success giving rise to gelator molecules with diverse molecular structures [9][10

Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation

• Kirsty L. Wilson,
• Alan R. Kennedy,
• Jane Murray,
• Ben Greatrex,
• Craig Jamieson and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2016, 12, 2005–2011, doi:10.3762/bjoc.12.187

• bases resulted in reaction with the solvent at room temperature (Table 2, entries 3, 5, 7, and 9–11). The extent of the reaction varied from the generation of additional components, such as 4a and 4b, to gelation or complete solidification of the reaction mixture. However, in a moderately basic reaction

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• inspired by the creative work of many researchers in the field at the time [21][22][23][24]. When it came time to assemble a set of job proposals, it seemed natural for one focused on molecular gelation. Specifically, I proposed to develop sensors wherein a chemical stimulus (analyte) reacts with a “latent

• gelator” and induces gelation (Figure 2). Gel-based sensors were appealing because they provide an unambiguous visual change in the material’s physical properties with no interference from colored or opaque samples. Moreover, no instrumentation or training is necessary to interpret the results, thereby

• providing a portable and potentially inexpensive method for sensing. Considering how naïve my understanding of gelation was at the time, I am still surprised that my proposal idea worked almost exactly as described. Molecular gels form through the self-assembly of small molecules into supramolecular

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• found that the adamantyl substituents aggregate in aqueous solution to form a micelle and that subsequent addition of α-CD leads to the formation of a supramolecular hydrogel as shown in Figure 11 [88]. The driving force for gelation is a combination of the hydrophobic aggregation of the adamantyl

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• silica. Small-angle X-ray scattering revealed that the homogeneous distribution of silica nanoparticles in solution was maintained in the gel state. Such homogeneous nanocomposite gels were obtained with at least 30 wt % silica content, and the Young’s modulus increased with silica content. Gelation did

• transparent, indicating no significant aggregation. Five gels were synthesized in the same way with different initial concentrations of silica nanoparticles. Notably, in the absence of silica nanoparticles, gelation did not occur; only a slight increase of viscosity was observed. This result clearly shows

• that the gelation was achieved mainly by the reaction between silica and TES-PR, with a parallel minor reaction occurring between the triethoxysilyl groups of different TES-PRs. To elucidate the dispersity of silica nanoparticles in the gels, small-angle X-ray scattering (SAXS) was carried out. Figure

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• their immunostimulant activities [21]. Finally, the ability of cholesterol derivatives to self-assembly and gelation as supramolecular gels was reviewed [22]. They are beneficially applicable in materials science, reaction media, sensing and responsive materials, energy supply, biomedicine, and tissue

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• -controlled gelation processes. TTF-based supramolecular chemistry in solution was thoroughly outlined in recent reviews of Jeppesen, Nielsen, and Becher (2004) [24], Iyoda, Hasegawa, and Miyake (2004) [25][26], Sallé and Zhang (2009) [27], and Martin (2009, 2012) [28][29]. However, limited examples of redox

• realize electrochemically-driven conformational control, redox-controlled gelation processes, redox switches, and molecular sensors. Furthermore, semiconductive fibers and rods of TTFs can be utilized for nanosized electric wires and wirings in nanoelectronics. The next key innovation in TTF-based

Synthesis and evaluation of the biostability and cell compatibility of novel conjugates of nucleobase, peptidic epitope, and saccharide

• Dan Yuan,
• Xuewen Du,
• Junfeng Shi,
• Ning Zhou,
• Abdulgader Ahmed Baoum,
• Khalid Omar Al Footy,
• Khadija Omar Badahdah and
• Bing Xu

Beilstein J. Org. Chem. 2015, 11, 1352–1359, doi:10.3762/bjoc.11.145

• .11.145 Abstract This article reports the synthesis of a new class of conjugates containing a nucleobase, a peptidic epitope, and a saccharide and the evalution of their gelation, biostability, and cell compatibility. We demonstrate a facile synthetic process, based on solid-phase peptide synthesis of

• (stargazin) [14] and LGFNI is from a synapse associated protein 102 (SAP102) [15]. We connected these two functional peptide sequences with a nucleobase, and saccharide (or not). After investigating the gelation, biostability, and cell-compatibility properties of these conjugates (1–8), we found that all the

• chromatography (HPLC) to purify the target conjugates. Gelation properties Supramolecular hydrogels [18][19][20][21][22][23][24] formed by self-assembly of small molecules in water, as demonstrated previously by us and other researchers, have numerous potential applications, such as encapsulation and delivery of

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• role in the gelation. Compound M6 is the only one that can gelate in ethanol, isopropanol and 1-butanol and the reversible gel–sol transitions are also investigated. To obtain visual insight into the microstructure of the gels, the typical structures of the xerogels were studied by SEM. Morphologies of

• can bring about new predictable gelation abilities for the construction of novel cholesterol-based gelators. Azobenzene is one of the smartest molecules among all known photochromic compounds because of its E/Z isomerization [18]. Based on this, photomechanical soft materials containing azobenzene

• relationship between the spacer length and the gelation ability of gelators. Herein we synthesized a series of compounds with different spacers between cholesteryl and azobenene units (Scheme 1). In these compounds, M6 is the only one that can gelate in ethanol, isopropanol and 1-butanol. It is found that

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• their cardiovascular, antifungal, anticancer [33][34][35][36] and antithrombotic activities [37] have been investigated. Gelation ability of the pentose derivatized diosgenyl saponins have also been reported [38]. In the family of diosgenyl β-glycosides D-glucopyranose is the first sugar attached to the

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

• Navneet Goyal,
• Hari P. R. Mangunuru,
• Bargav Parikh,
• Sonu Shrestha and
• Guijun Wang

Beilstein J. Org. Chem. 2014, 10, 3111–3121, doi:10.3762/bjoc.10.328

• better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually

• enhanced the gelation tendency for many derivatives. The introduction of the additional methoxy group on the phenyl ring led to low molecular weight gelators with a higher pH responsiveness. The resulting gels were stable at neutral pH values but degraded in an acidic environment. The release profiles of

• naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation. Keywords: glucosamine; hydrogelators