Study on the interactions between melamine-cored Schiff bases with cucurbit[n]urils of different sizes and its application in detecting silver ions

• Jun-Xian Gou,
• Yang Luo,
• Xi-Nan Yang,
• Wei Zhang,
• Ji-Hong Lu,
• Zhu Tao and
• Xin Xiao

Beilstein J. Org. Chem. 2021, 17, 2950–2958, doi:10.3762/bjoc.17.204

• addition, the UV–vis spectrum in Figure 4a shows that the absorbance of TBT keeps on the decrease (ΔA = 0.623) without red shift or blue shift in the presence of Q[8]. Both of the above phenomena show that Q[8] interacted with the “arm” of TBT and produced precipitation due to aggregation, which is also

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

• (Supporting Information File 1, Figure S5a) with a corresponding ΦPL of 29% under N2. The significantly red-shifted emission in the PMMA film compared to that in toluene coupled with a significantly lower ΦPL is suggestive that aggregation-caused quenching is prevalent in this host matrix. Transient PL

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

• aggregation of Nagg ≈ 1,200 and a length of 110 nm for BTU (assuming four units per cross-section), as well as a weight-average molar mass of Mw = 4,406,000 g⋅mol−1, corresponding to a number of aggregation of Nagg ≈ 490 and a length of 120 nm (assuming two units per cross-section) for BTP, could be observed

• , corresponding to a number of aggregation of Nagg = 1400 and a length of 125 nm for BTU (assuming four units per cross-section). For BTP, a weight-average molar mass of Mw = 2,910,000 g⋅mol−1, corresponding to a number of aggregation of Nagg = 440 and a length of 80 nm (assuming two units per cross-section) was

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• material [4][5][6][7]. Aggregation and interactions with the cell membrane of bile acid molecules can alter drug action [8][9]. Our previous work showed that bile acids could interact with certain drug molecules and improve their biological activity [10][11]. To evade the membranolytic action of natural

• obtained in this way were subjected to antiproliferative activity testing in vitro. It is worth mentioning that the fused tetrazole derivatives of bile acids may possess better hydrophobic–hydrophilic balance, important for aggregation properties, which could be an interesting topic for future research

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

• and without triphenylphosphonium (TPP) as mitochondria targeting units. In order to keep the aggregation number, and therefore the size of the nanoparticle, constant, we opted to post-functionalize the nanoparticles with TPP to facilitate the study of the effect of TPP only. Aim of this project is to

• way to ensure high end group fidelity. This is of course true, but it also needs to be considered that the presence of the end group will influence the PISA process and results in aggregation numbers and particle sizes that are very different to the ones obtained with unmodified RAFT agent. Due to the

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

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• the strong base led to the formation of the over-aminated product 168 (Scheme 22b) [110]. Alzheimer’s disease is caused by the β-amyloid-42 aggregation in brain tissue [111][112]. In 2017, Sreenivasachary synthesized a library of 6,5’- and 6,6’-bis(indolyl)amines and other similar 7-azaindole

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

• modification can be prepared. Strategically introduced PGs can be selectively removed to insert a branch or a chemical modification. However, to date, this approach has suffered dramatically from the severe aggregation and insolubility of cellooligosaccharides, permitting to obtain only relatively short

• , fluorine, and carboxymethyl groups, prevented the formation of insoluble aggregates by disrupting hydrogen-bond networks. Dramatic differences in the conformation (e.g., radius of gyration and glycosidic bond conformation) and aggregation behaviour (i.e., crystallinity and solubility) were observed for

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• vulnerabilities. Limited water solubility, especially for purine rich sequences, was noted in early studies. To improve water solubility and decrease aggregation, typical PNA designs place a lysine at the C-terminus (Figure 1) introducing a second positive charge in addition to the charge at the N-terminus of PNA

• folding in compact structures and aggregation in concentrated solutions [13]. Other bottlenecks for in vivo applications of PNA have been poor cellular uptake and unfavorable pharmacokinetics [14][15][16]. Unmodified PNAs are not taken up by eukaryotic cells in vitro and are cleared rapidly (within 10–30

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

• = 0.07 cm2⋅V−1⋅s−1. Isoindigo-based sensor devices Isoindigo derivatives have begun to find an application in the design of sensor devices for the detection of simple and complex molecules in various aggregation states. Thus, it was shown that polymer structures based on isoindigo and thiophene 59a,b and

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• exhibit photophysical properties such as photosensitization [13], fluorescence, and aggregation-induced emission (AIE) [14][15][16]. π-Conjugated polycyclic hydrocarbons (CPHs) containing polycyclic heteroaromatic molecules (PHAs) and aza-polycyclic aromatic hydrocarbons (aza-PAHs) have been attracting

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• folding kinetic pathways can also lead to aggregation and misfolding issues, affecting the protein production. 2.7 Other properties The acid–base transitions also appear altered in fluoroprolines primarily due to the electron-withdrawing effect of the fluorine atoms (Table 2) [16][19][55][57][58]. This

• relies on its production, which is mainly achieved via living cells. If fluoroprolines alter the protein folding, a misfolded sample would usually be prone to aggregation and/or degradation by the cellular machinery. This may be seen as a lack of protein production or as the protein being insoluble. Only

• -Flp), 3) a lack of interaction with chaperones, 4) misfolding that leads to aggregation, 5) an inhibitory effect of the target protein on the cellular machinery and 6) misfolding that leads to rapid degradation of the protein, to name a few. A misfolding can occur for reasons such as an altered

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• difficulties associated with performing multidimensional experiments at a fast enough rate to follow the aggregation process accurately. Despite these aforementioned challenges the Marsh laboratory has recently demonstrated the utility of 19F NMR to access direct, sensitive and real-time observation of amyloid

• fibril formation, enabling the elucidation of the underlying mechanics of peptide fibrillation. To study the aggregation mechanism of the model Aβ-peptide, a well-known amyloidogenic peptide related to Alzheimer’s disease, Marsh and collaborators synthesized a 19F-labelled Aβ1−40 peptide version in which

• methionine at position 35 was replaced by tfmMet (Aβ1−40-tfmMet35) [9][62]. The aggregation process was then monitored by 19F NMR over a period of several weeks [62]. Upon analysis, formation of at least six spectroscopically distinguishable intermediates could be detected during fiber formation (Figure 10

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

• cationic building blocks Flavy and poly(allylamine) are mixed first, the aggregation yields clearly polydisperse ternary samples (Table 8 and Table 9). For understanding, it is of interest to consider the intermediate bi-component system, which already leads to polydisperse samples for loading ratios l

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• this supramolecularly driven photopolymerization (0.0305 min−1) could be enhanced by decreasing the aggregation of PDI via host–guest interactions. Recently, Wang and co-workers fabricated the orthogonal supramolecular ternary self-assembled system 27@CB[7]/EY via host–guest interactions between CB[7

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• fluoroiodoazobenzenes with varying fluorination degree at the iodobenzene moiety was used to investigate the impact of halogen bonding on the properties of the assemblies. Since cyanostilbene molecules are known to show aggregation-induced emission (AIE) behaviour the photophysical properties of the resulting

• interactions and packing in the solid state and adds to the shift of the crystallisation temperature. Photophysical studies Recently, our group has shown that self-assembly provides an efficient way to tune fluorescence behaviour of liquid crystalline materials [21]. Phenolic thioethers showing aggregation

• aggregation at room temperature (λex = 365 nm). Transition enthalpies of all compounds and assemblies upon heating and cooling as determined by DSC (heating/cooling rate of 10 °C/min). Supporting Information Supporting Information File 244: Detailed descriptions of the experimental procedures and

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

• ; inversion of CPL handedness; Tröger's base; Introduction Recently, much effort has been devoted to constructing luminescent materials with efficient high emission in the solid state [1][2][3]. More and more types of fluorophores with aggregation-induced emission (AIE) characteristics have been discovered

• considering the side chain. At the same time, the loose stacking of the TB unit and its derivatives, which is caused by its V-configuration could reduce the distance-dependent intermolecular quenching effect in the aggregation state [16]. Moreover, the large dihedral angle of TB (80–104°) [15] permits less

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

• in its length from the standard single C(sp2)–C(sp2) bond (ca. 1.48 Å). The X-ray analysis of quinoxaline-fused [6]helicene 10a revealed the presence of the face-to-face π–π interaction between the helicene aggregates. The racemic aggregation was composed by (P)- and (M)-enantiomers on the manner of

Secondary metabolites of Bacillus subtilis impact the assembly of soil-derived semisynthetic bacterial communities

• Heiko T. Kiesewalter,
• Carlos N. Lozano-Andrade,
• Mikael L. Strube and
• Ákos T. Kovács

Beilstein J. Org. Chem. 2020, 16, 2983–2998, doi:10.3762/bjoc.16.248

• concentration, only the spent media of ∆ppsC and ∆pksL affected the growth of L. fusiformis, even though it was weakened compared to using higher concentrations. Intriguingly, a higher level of aggregation was observed in the L. fusiformis assays supplemented with the spent medium of sfp compared to the other

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• -electron donating capability. Interestingly, upon aggregation in water-containing media, H, Me and t-Bu show a slight red-shift of the emission and a blue-shift is observed for OMe, SMe and NMe2. The crystal structure of Me allowed a detailed discussion of the structure–property relationship. Clearly, N

• substitution and environment is reported with potential applications in sensing, bioimaging and optoelectronics. Keywords: aggregation caused quenching (ACQ); aggregation-induced emission enhancement (AIEE); naphthalonitriles (NCNs); solution and solid state emitters (SSSE); solvent quenching (SQ

• aromatic rings that emit efficiently in very dilute solutions. However, the photoluminescence quantum yields tend to decrease or even fully quench in the aggregated or solid states, due to the well-known effect of aggregation caused quenching (ACQ) [9][10]. This is mainly related to intersystem crossing

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

• reductions were noticed for the N ≥ 10 derivatives (Figure 2a and Supporting Information File 1, Table S1), with the highest change being exhibited by PBIm14. These observations suggested that in going to higher concentrations, there was a gradual increase in the aggregation of the longer chain derivatives

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• water/methanol 1:2 (v/v). These anions caused the bright red solutions of the nanoparticles to change their color because of nanoparticle aggregation followed by precipitation, whereas halides or oxoanions such as sulfate, nitrate, or carbonate produced no effect. The sensitivity of phosphate sensing

• formed, the solutions either lose their color because of nanoparticle precipitation or they adopt a different color. Dispersed spherical AuNPs with a diameter of ca. 10 nm lead to intensely colored red solutions, for example, which turn purple or blue upon nanoparticle aggregation because the localized

• . The extent of aggregation of AuNPs containing peripheral phosphate groups in the presence of an externally added low molecular weight bis(zinc(II)–DPA) complex could be controlled by diphosphate anions, which in turn allowed correlating the optical properties of the nanoparticle solution with the

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• occur over longer times, suggesting that shear, friction, and collision effects did not anymore affect the β-CD particle size and morphology over time. In fact, crystal breaking reduced the particle size up to some critical threshold, as a result of the equilibrium between comminution and aggregation

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• of a charged ligand leads to a net reduction of charge in the complex, which likely increases the chance of aggregation due to hydrophobic interactions (see the red spectrum in Figure 3 as an example). Furthermore, some ligands exhibit a “molecular glue” effect by binding to two proteins

• simultaneously and thus induce aggregation [23][24][25][27][82]. This behavior does not interfere with identifying the ligand binding site, but it makes it difficult to determine a binding constant from the chemical shift perturbations since fitting a binding curve requires sufficient saturation of the signal

• . If a signal broadens beyond detection and thus disappears from the spectrum, be it due to aggregation or intermediate exchange kinetics, it is also impossible to trace its trajectory and determine the chemical shift perturbation. In the case of a bifunctional GCP ligand binding to survivin [46], the

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• use. Particularly, some enaminones I and II were found to show antioxidant [3], antimycotic [7][8], antimycobacterial [9][10], anti-Alzheimer’s disease (JNK3 inhibitors) [11], platelet aggregation inhibitory [12], antimicrobial [7] and analgesic [13] activities. Enaminones II were reported as

• potential Cu2+ chemosensors [14], and their BF2 chelates, as multicolor fluorescence complexes, some of which exhibited aggregation-induced emission (AIE) properties [15]. In addition, enaminones I and II proved themselves to be versatile and available building blocks for the synthesis of various