Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• insulin Schmuck and co-workers reported a supramolecular ensemble in combination of a pyrene-tagged amphiphilic peptide beacon (6) and a macrocyclic host (cucurbit[8]uril, CB[8]) for ratiometric fluorescent detection of amino acid derivatives, specific peptides, and proteins in aqueous media (Figure 6

• bacteria [57]. It is a glycolipid consisting of a variable polysaccharide domain connected to a conserved glucosamine-based phospholipid called lipid A. It is highly negatively charged due to two phosphorylated groups in the lipid A part and carboxylated groups in the polysaccharide part. It is amphiphilic

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

• interaction of the alkyl chains. Keywords: dirhamnolipid ester; gemini surfactant; rheology; reverse wormlike micelle (RWLM); Introduction Surfactants have both hydrophilic and hydrophobic groups and are therefore amphiphilic molecules. Due to their unique molecular structure, surfactants are essential

Easy access to a carbohydrate-based template for stimuli-responsive surfactants

• Thomas Holmstrøm,
• Daniel Raydan and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2020, 16, 2788–2794, doi:10.3762/bjoc.16.229

• hydrophilic and a lipophilic domain, thereby rendering them amphiphilic. This dual functionality gives surfactants unique properties such as being able to stabilize emulsions (emulsifiers) or forming large self-assembled aggregates that can take the shape of, for example, micelles or liposomes [1]. The latter

• surfactants: amphiphilic molecules that can alter their properties upon an external stimulus [6]. The intelligent surfactants are not passive but designed to undergo a molecular change when it is triggered with either a change in the pH value [7][8], upon light irradiation [9] or in the presence of metal ions

• [10][11]. Common for all of the systems is that the hydrophilic head group can undergo a conformational change upon an external stimulus. The head group is typically functionalized with two lipophilic tails rendering the compound amphiphilic. The conformational change of the head group acts as a

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• to an n-alkyl chain at the other, underwent self-assembly in aqueous media depending on the length of the alkyl segment. The amphiphilic derivatives having n-decyl or longer chains, formed nano-assemblies with cyanic–green emission resulting from the stacked pyrene chromophores in the aggregates. The

• the nucleotides occurring through multivalent electrostatic interactions in the cavity/cleft created by the spatial orientation of the imidazolium groups. We herein consider a self-assembly based approach in which amphiphilic monomers with bisimidazolium moieties are utilized to create multivalent

• buffer (Figure 2b) also showed a significant difference between PBIm4 and the three amphiphilic derivatives. For example, the amphiphilic derivatives exhibited structured emission bands around 376 nm, 396 nm and 417 nm as well as a broad structureless band centered around 480–490 nm (PBIm10: 481 nm

Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides

• Dongsik Yang,
• Hongjian He and
• Bing Xu

Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221

• ][20][21][22][23][24][25][26], as mimicry of amyloids [27], in the context of intracellular phase transition [28], and in molecular imaging [29][30]. Most of these studies are centered on peptide amphiphiles or amphiphilic peptides that are linear in geometry. Nature, however, also produces and

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• hydrophobic effect and to host–guest π–π interactions. Hydrophobic surface simulations showed that TBTQ-(OG)6 and C60 forms an amphiphilic supramolecular host–guest complex, which further assembles to microspheres with diameters of 0.3–3.5 μm, as determined by scanning electron microscopy. Keywords

• of this host with C60 and C70-fullerene was investigated in co-organic solvents and in aqueous solution. The hydrophobic surface simulation of this host indicated the formation of a supra-amphiphilic system, which, as shown by scanning electron microscopy, further self-assembles into microspheres in

• of 0.3–3.5 μm were observed for the complex TBTQ-(OG)6 C60. Obviously, these aggregates form by further assembly of the supra-amphiphilic host–guest systems, as suggested in Figure 6c, due to the hydrophobic interactions governing the association behavior of TBTQ-(OG)6 C60 in water. Conclusion In

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• renders PEP-1 amphiphilic in nature, which is expected to be beneficial for aqueous self-assembly. The polar Glu and Arg motifs are also sensitive towards basic and acidic pH values, respectively. PEP-1 is actually a naturally occurring β-strand peptide fragment (residues 16−23 in Figure S1, Supporting

• Information File 1) of galectin-1, a β-sheet lectin protein that is available in bovine spleen [53] (for a detailed crystal structure see the Protein Data Bank; PDB ID 1SLT). Given the amphiphilic and pH-responsive nature of PEP-1, we investigated both the pH- and concentration-dependent formation of

• (Glu−) amino acids [73][74]. Mechanistic insights into the observed conformational transformation via molecular dynamics simulations are underway in our laboratory. Conclusion In summary, we synthesized a naturally occurring amphiphilic peptide fragment, PEP-1, from a β-sheet lectin protein, galectin-1

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• aerosol-assisted self-assembly using amphiphilic triblock copolymers as template and low-molecular weight soluble phenol resin as carbon source. The amphiphilic surfactant influences the pore size and mesostructure of the resulting spherical carbons. Finally, the template is removed by calcination [97

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• macrocycles are a class of steroid-based receptors which can host polar molecules in nonpolar solvents because of their amphiphilic nature. As a result, their design and synthesis has been a topic of substantial research interest in supramolecular chemistry [32][33]. Various synthetic methods have been

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• metathesis polymerisation (ROMP) to generate facially amphiphilic polymers [182][235][237][238]. Ilker et al. employed the DAC between alkyl pentafulvenes and maleic anhydride to initially prepare norbornene anhydride monomers that could be further functionalised to afford norbornene imide monomers (Scheme

•  21) [105][237]. ROMP of the monomers, followed by deprotection yielded facially amphiphilic polynorbornenes that displayed lipid membrane disruption and antimicrobial activities [237][238]. The facially amphiphilic polynorbornenes with pendent ammonium groups were found to disrupt negatively charged

• [190]. Preparation of hydrogels via Diels–Alder cycloaddition with fulvene-conjugated dextran and dichloromaleic acid-modified poly(ethylene glycol) [191]. Ring-opening metathesis polymerisation of norbornene derivatives derived from fulvenes and maleimides to furnish facially amphiphilic polymers

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• -assemblies with a tunable morphology transition ability. According to the literature [43][44], some nonspherical supramolecular self-assemblies seemed to be more efficient in the cellular internalization. Thus, we intend to design AB2-type amphiphilic HGCMs to form nonspherical supramolecular self-assemblies

• on pH-responsive supramolecular self-assemblies by utilizing β-CD-benzimidazole2 (β-CD-BM2) as AB2-type amphiphilic HGCMs for the delivery and controlled release of doxorubicin (DOX). β-CD-BM2 was first synthesized by click reaction (Scheme 1a). β-CD-BM2 formed fan-shaped self-assemblies (FSSAs) at

• hydrophobic core and β-CD moieties as outer hydrophilic shell. The basic cell experiments confirmed that the pH-responsive supramolecular self-assemblies based on β-CD-BM2 have a potential application in the field of drug delivery. Results and Discussion Synthesis of the host–guest-conjugated amphiphilic

Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

• Dong-Hao Li and
• Bradley D. Smith

Beilstein J. Org. Chem. 2019, 15, 1086–1095, doi:10.3762/bjoc.15.105

• of polar functional groups and non-polar surfaces which is reminiscent of the amphiphilic binding pockets within many proteins. In water, the aromatic surfaces in the tetralactam cavity drive high affinity due the hydrophobic effect and the NH groups provide secondary interactions that induce binding

• selectivity. In organic solvents, the supramolecular factors are reversed; the polar NH groups drive high affinity and the aromatic surfaces provide the secondary interactions. In addition to an amphiphilic cavity, macrocyclic tetralactams exhibit conformational flexibility, and the combination of properties

• amphiphilic cavity – that is, a cavity containing a mixture of polar functional groups and non-polar surfaces in close proximity – is likely to be a versatile receptor with the potential to bind guests in both non-polar organic solvents and water [4][5][6][7][8][9][10][11][12][13]. Macrocyclic tetralactams

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• substituted fullerenol with five substituents on one pole of the fullerene and polyhydroxylation moieties, mostly ether and hydroxy groups, on the rest of the fullerene core. As substituents a broad variety of primary amines can be used to obtain Janus-type amphiphilic fullerenols in good to excellent yield

• is hydroxylated are known [25][26], literature lacks fullerenol compounds with Janus-type substitution. The advantage of those special molecular species, e.g., amphiphilic behaviour, was demonstrated in a paper published by our group in 2018 [27]. A fullerenol derivative with a maximum of 21 OH

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• reported on the reactivity of oxenoids [74][75][76][77], indicating that the reaction of a nucleophile with oxenoid proceeds through an SN2 process [74]. Following the carbocupration of cyclopropene 3 into cyclopropylcopper species, the subsequent oxidation with the amphiphilic lithiated hydroperoxide t

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• on the catalytic activity of the reaction. In fact, catalyst and substrate are encapsulated into emulsion droplets formed in the reaction media above the aqueous layer, making the reaction proceed “on water” [21][22]. The introduction of amphiphilic molecules for aqueous micellar catalysis allows

• tags. c) PEG-tethered catalysts. Chemical structure and components of amphiphilic molecule PTS and derivatives. In vivo metathesis with an artificial metalloenzyme based on the biotin–streptavidin technology. Most common metathesis reactions. Ring-opening metathesis polymerization (ROMP), acyclic diene

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

• 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

• . Changes in the synthetic stage sequence led to variable layer compositions. Various linear and star-shaped (triarm) ABA and ABCBA amphiphilic multiblock copolymers containing acetal-protected sugars (APS) were prepared by the coupling of an end-functionalized ROMP copolymer of norbornene (NB) and APS

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• ]. Characterized by an amphiphilic nature with either hydrophobic “barrel” interiors and hydrophilic surfaces (as in globulins, carriers of hydrophobic molecules and fluorescent proteins) or hydrophilic cores and hydrophobic surfaces (as in membrane-bound β-barrels like porins and channel proteins), they can be

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

• use of vitamin B12 [116]. Furthermore, cobalester, an amphiphilic vitamin B12 derivative with six ester groups and a nucleotide loop, has recently been developed to show good catalytic activity for C–C bond forming reactions [117][118]. The above-mentioned visible-light-driven system composed of 1

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• crossbar architecture in which a monolayer of amphiphilic rotaxanes is sandwiched by a bottom Si nanowire electrode and a top Ti nanowire electrode. Both layers of nanowires are orthogonal to each other. This produces several crossing points or “junctions” whose areas are defined by the diameter of the

• states of 19. Schematic representation of a molecular electronic memory based on a bistable TTF-based rotaxane. (a) Molecular structure of the amphiphilic [2]rotaxane 20. (b) Structure of the crossbar device. (c) Switching mechanism of rotaxane 20 in a junction. Schematic representation of bending motion

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

• hand, solvents such as methylene chloride, chloroform, xylene, benzene and toluene were gelled by 2 but not by 3. Thus, compound 3 can be an alternative to compound 2, and vice versa, depending on the solvent to be gelled (see below). Similarly to other amphiphilic gelators [21][29][31], the formation

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• /bjoc.14.173 Abstract The synthesis of new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide fragments on the upper rim and water-soluble triazolyl amphiphilic receptors with two or four polyammonium headgroups via copper-catalyzed azide–alkyne cycloaddition reaction has been

• ]. Calixarenes are easily functionalized at both their upper and lower rims with various stereoisomers obtainable; the initial macrocycles can be synthesized in a simple manner, they are not toxic, etc. [17][18][19][20][21][22]. Amphiphilic calixarenes are particularly interesting because they can be regarded as

• high affinity to ATP [26]. Herein we report the synthesis of new amphiphilic water-soluble calix[4]arene derivatives with cone conformation containing two or four polyammonium groups on the upper rim by using a click chemistry approach and the results of binding studies toward nucleotides in aqueous

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• /hydrophilic ratio in a molecule largely affects its assembled properties in aqueous media. In this study, we synthesized a new bicyclic compound which could dynamically change its hydrophobic/hydrophilic ratio by chemical stimulus. The bicyclic compound consisted of amphiphilic pillar[5]arene and hydrophobic

• aggregation of the hydrophobic alkyl chain rings, which induced insolubilization of the bicyclic compound in aqueous media at 20 °C and a decrease in its clouding point. Keywords: amphiphilic molecules; host–guest complexes; lower critical solution temperature; pillar[n]arenes; pseudo[1]catenane

• –guest chemistry [5][6][7]. The molecules consist of a non-ionic amphiphilic part containing tri(ethylene oxide) moieties, and a hydrophobic part consisting of a pillar[n]arene core (Figure 1a; 1, n = 5; 2, n = 6). Pillar[n]arenes, which were first reported by our group [11], were used as the macrocyclic

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• Background: 4-(n-Octyloxy)aniline is a known component in the elaboration of organic materials with mesogenic properties such as N-substituted Schiff bases, perylene bisimide assemblies with a number of 2-amino-4,6-bis[4-(n-octyloxy)phenylamino]-s-triazines, amphiphilic azobenzene-containing linear-dendritic

• (ethynyl)-s-triazine and various icosanyloxyphenylazides) with liquid crystalline and luminescent properties [22]. On the other hand, mesogenic supramolecular perylene bisimide assemblies with a number of 2-amino-4,6-bis[(4-alkoxy)phenylamino]-s-triazines [23], amphiphilic azobenzene-containing linear

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• section we will discuss the utility of some of the well-established catalytic nanoreactors towards green(er) chemistry [62]. 2.1. Micelles Micelles are supramolecular architectures that are assembled of amphiphilic molecules [41]. Above the critical micellar concentration (CMC), surfactants with the

• effect for hydrophobic substrates, which ensures higher reaction rates than those performed in bulk [63]. Besides, the structure of any micellar catalytic environment is governed by the arrangement of the amphiphilic molecules, creating, in many cases, a regioselective environment (Figure 1) that affects

• is occurring in the lipophilic pocket and not in water. The authors also demonstrated the ability of the PQS system to be recycled up to 10 times without loss in its catalytic activity. Catalytic micelles were also prepared by O’Reilly et al. when a novel amphiphilic Sulfur–Carbon–Sulfur (SCS) pincer

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• cytokines, chemokines, prostaglandins and reactive oxygen species which manifest an acute inflammatory response to infection. The “endotoxic principle” of LPS resides in its amphiphilic membrane-bound fragment glycophospholipid lipid A which directly binds to the TLR4·MD-2 receptor complex. The lipid A

• -hydrophobic labeling reagents for amphiphilic glycoconjugates such as lipid A. 1.4. Synthesis of Helicobacter pylori Kdo-lipid A substructures A Helicobacter pylori infection of the gastric mucosa causes chronic gastritis in humans and plays a pivotal role in the progression and pathogenesis of peptic ulcer