Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• non-radiative transitions can be achieved by the host–guest method [50][51][52] or by crystallization [53][54][55][56][57]. In difference to the liquid phase, the highly ordered packing and the restriction of molecular motions in the crystalline state favor a persistent luminescence. The promotion of

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• stereoselective approaches of substrates and reagents or catalysts in a variety of processes. Examples include the substrate–enzyme recognition (the host–guest interaction) responsible for inducing pharmacological activity, the DNA-intercalation capable of generating biomolecular activity, molecular dynamics [63

Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• , high singlet and triplet energies (higher than those of the guest) are required for host compounds for qualifying host–guest energy transfer, thus implying restrict of the emissive excitons on the TADF emitters [11]. High glass-transition temperatures are also required for increasing the morphological

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• Xiaodong Zhang Jun Xie Zhiling Xu Zhu Tao Qianjun Zhang Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.16.9 Abstract The host–guest interactions between baicalein (BALE) and cucurbit[8]uril (Q[8]) and the

• corresponding properties of the inclusion complex were studied using 1H NMR, IR and UV–vis spectroscopy and DTA. The results showed that BALE forms an inclusion compound (1:1) with Q[8], and the properties of baicalein are changed by cucurbit[8]uril. Keywords: baicalein; cucurbit[8]uril; host–guest interaction

• compounds such as calixarenes, crown ethers and cyclodextrins, which can be used to form a stable inclusion complex with the drug, and improving the bioavailability of the drug [34][35]. Herein, we describe the results of the investigations of host–guest interactions between BALE and Q[8] in an aqueous

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• , as elucidated by the crystallographic structure of a 1:1 host–guest BAPTA system [2]. This moiety has been exploited in the development of various fluorescent supramolecular chemosensor systems and even molecular logic systems [3][4][5][6][7][8][9][10][11]. Equally, the incorporation of

A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

• Constantin Stuckhardt,
• Diederik Roke,
• Wojciech Danowski,
• Edwin Otten,
• Sander J. Wezenberg and
• Ben L. Feringa

Beilstein J. Org. Chem. 2019, 15, 2767–2773, doi:10.3762/bjoc.15.268

• between the three isomers. Two of the isomers were able to form host–guest complexes opening up new prospects toward stimuli-controlled substrate binding and release. Keywords: coordination cages; molecular motors; molecular switches; overcrowded alkene; palladium; Introduction Supramolecular

• metal centers has been used to control host–guest interactions [25][26][27][28], structural composition [29], and sol–gel transition [30]. However, dithienylethene undergoes a limited structural change upon photoisomerization and, up to now, photoswitchable ligands based on other types of photochromic

• formed revealing that a chiral self-sorting process takes place. In addition, two of the cage isomers can bind a tosylate anion in solution by formation of a host–guest complex. Results and Discussion Ligands Z-1 and E-1 (Scheme 1) were synthesized by a Suzuki cross-coupling reaction of 3

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• and studied by multiple gas-phase techniques, ESI-QTOF-MS, IRMPD, and DT-IMMS experiments, as well as DFT calculations. The comparison of classical resorcinarenes with pyridinearenes by MS and NMR experiments reveals clear differences in their host–guest chemistry and implies that cation encapsulation

• synthesis of pyridine[4]arenes dates back to 2001 [4], their host–guest chemistry is still under-explored. Both macrocycles are concave and are known to form capsular assemblies via intermolecular hydrogen bonding [5][6]. Pyridine is significantly less electron-rich than benzene. Consequently, pyridinearene

• dimeric resorcin[4]arene and pyridine[4]arene capsules, we highlight here unique host–guest properties of pyridinearene capsules. In marked contrast to the corresponding resorcin[4]arene capsules, cation binding is clearly feasible, when anions bind in an exo-site and support cation encapsulation by

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• multiple host–guest correlations (see Figure S6 in Supporting Information File 1 for a full-range spectrum). For example, E-1’s protons Hd at 6.22 ppm correlate both with the resonances at 7.78 ppm and at 7.57 ppm, which all originate from 2’s protons (H2 + H3 and H5 + H7, respectively). Similarly, the Ha

• a premade complex of 2 with a tightly bound guest, tetra-o-fluoroazobenzene [49], no acceleration effect was observed. Conclusion In summary, we investigated the encapsulation and switching of a prototypical arylazopyrazole in the hydrophobic cavity of a water-soluble metal–organic cage. A host

• –guest inclusion complex incorporating two molecules of arylazopyrazole was obtained in a quantitative yield. The complex was characterized by a series of NMR techniques, which showed that the resonances of the guest protons were upfield-shifted by up to 2.2 ppm. An antiparallel configuration of the

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

• -triazolium macrocycles; Review 1. Introduction Supramolecular chemistry – “The chemistry beyond the molecule” [1] – is an ever growing interdisciplinary area has emerged from the early host–guest chemistry to more elaborate bio-inspired supramolecular aggregates by exploiting various noncovalent

• interestingly, based on the results and control studies, Li’s group have proposed the ability of macrocycle 15 (triiodide form) to act as a nanoreactor by the photo-driven dimerization of tetracyano-para-quinodimethane (TCNQ). The proposed mechanism consists of 7 steps: the formation of a 1:1 host–guest [15

• interactions, compared to monovalent receptor–ligand interactions offer the advantage of multiple and sequential binding within the host–guest systems. These noncovalent interactions which can be controlled in a chemical or physical manner depend on the binding sites in the multivalent assembly [67

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• noncovalent interactions between anions and the tetrazine rings. Keywords: anion–π interactions; coronarenes; host–guest complexation; N-functionalized phthalimides; O6-corona[3]arene[3]tetrazines; Introduction Synthetic macrocycles [1][2] are always attractive and important because they are unique

• ability of 3a to bind various anion species in gas phase. To our delight, host molecule 3a co-crystalized with n-Bu4NX (X = Cl, Br) from diffusion of diethyl ether vapor into ethyl acetate solution at ambient temperature to give single crystals of the host–guest complexes (n-Bu4NX)3-3a (X = Cl, Br). X-ray

• crystallography then allowed us to understand the host–guest interactions at the molecular level. As illustrated in the molecular structures in Figure 4, above the centroid of each tetrazine ring there resided a chloride or a bromide. The distance of the anion to the centroid of tetrazine ranged from 3.060 Å to

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

• -responsive supramolecular self-assemblies have been constructed, the controlled drug delivery induced by morphology transitions of these supramolecular self-assemblies on the basis of host–guest-conjugated monomers (HGCMs) are few reported. In this paper, the self-assembly behaviors of AB2-type HGCMs, e.g

• varied morphology could inhibit cancer cell proliferation, indicating their potential application in the field of drug delivery. Keywords: β-cyclodextrin; controlled drug delivery; host–guest interaction; stimuli-responsive; supramolecular self-assemblies; Introduction Supramolecular self-assemblies

• based on noncovalent interactions with dynamic nature and reversible property have attracted increasing attention in the fields of biomedicine [1][2][3][4][5][6][7], smart materials [8][9][10], etc. As one common noncovalent interaction [11], host–guest interaction has been used to effectively create

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• a hydrophobic effect, while the other one has a more directional character, or application of multidentate interaction sites [3]. Macrocyclic compounds with persistent hydrophobic cavities constitute a fundamental class of scaffolds for the construction of supramolecular host–guest complexes in

• manifested in chirality transfer. We will also present a crucial and non-intuitive solvent dependence. RSAs (e.g., 1) can be considered as analogues of calix[4]arene sulfonic acids (CSAs) – the class of macrocycles widely studied in the context of various host–guest interactions, especially with various

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• face with primary hydroxy groups and a wider secondary face with secondary hydroxy groups [6][7]. With the hydrophobic cavity and the hydrophilic hydroxy groups, CDs efficiently form host–guest complexes with different hydrophobic guests in aqueous medium [8][9]. Among the common CDs, γ-CD possesses a

• relatively large cavity size that could accommodate up to two aromatic guests to form 1:2 host–guest complexes, in contrast to the usual formation of 1:1 complex by α-CD and β-CD [10][11]. In addition to host–guest chemistry, the favourable binding of CDs to common organic scaffolds has also made CDs popular

• efficiently obtained by using both CB[6] and γ-CD which are interlocked onto the axle by orthogonal interactions. Of note, the γ-CD in all the rotaxanes are only singly threaded, suggesting that further guest molecules could bind to the γ-CD cavity to give interesting host–guest complexes with the [n

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• ; macrocycles; macrocyclic arene; Introduction Macrocyclic host molecules [1][2] play a significant role in host–guest chemistry. Compared with noncyclic molecules, the structures of macrocyclic hosts can greatly enhance the host–guest complexation ability through preorganization. Moreover, cyclic structures

• methenyl groups. They have been a kind of important macrocyclic host molecules during the last decades due to their unique structures and a wide range of applications in host–guest chemistry [13][14][15][16][17][18], self-assembly [19], biomedicine [20] and materials science [21][22]. The derivatives of

• macrocyclic arenes with diverse functional groups are also important for the development of various new host–guest supramolecular systems [23][24][25][26][27][28][29]. Helic[6]arenes [30], a new kind of macrocyclic arenes, are composed of 2,6-dihydroxy-substituted triptycene subunits bridged by methylene

Host–guest interactions in nor-seco-cucurbit[10]uril: novel guest-dependent molecular recognition and stereoisomerism

• Xiaodong Zhang,
• Wei Wu,
• Zhu Tao and
• Xin-Long Ni

Beilstein J. Org. Chem. 2019, 15, 1705–1711, doi:10.3762/bjoc.15.166

• ]. Keywords: fluorescent; host–guest interaction; macrocycles; molecular recognition; nor-seco-cucurbit[10]uril; pyrene; Introduction Host–guest interactions that trigger molecular recognition are a current topic of interest. For example, understanding the protein–ligand molecular recognition is of paramount

• importance in the study of enzymatic catalysis and allosteric regulation of cell signaling, as well as in the design of efficient drugs that utilize host–guest interactions [1]. Cucurbit[n]urils (Q[n]s or CB[n]s) [2][3] having been viewed to have high potential use in host–guest chemistry in aqueous solution

• ] was functionalized with imidazolidone (host-2, Scheme 1) [28]. Herein, we report the supramolecular host–guest interactions of the two cavities of NS-CB[10]-based host-1 and host-2 with two unsymmetrical ADA-based derivatives (G1 and G2, Scheme 1). As expected, hosts-1 and -2 are capable of

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• guest receptors [4][5]. Planar-chiral macrocyclic molecules are particularly interesting in the context of the host–guest complexation properties [6][7][8]. Pillararenes are typical examples of this type of compounds and have attracted considerable attention due to their facile chemical synthesis and

• was 4.8 ns, which is very similar to DPA-6 (5.0 ns) and the non-substituted DPA (5.3 ns) [42]. The fact that grafting DPA units in one host did not influence the fluorescent quantum yield together with the appealing host–guest properties make P5A-DPA an ideal candidate for applications as acceptor for

• adding water into the THF solution. This work presented a new strategy for achieving versatile planar chiral hosts, and these hosts will have potential applications in various fields such as supramolecular sensing, host–guest recognition and triplet–triplet annihilation upconversion. Experimental General

Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

• Stiliyana Pereva,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163

• supramolecular host–guest structures. The water content of CDs has been a subject of numerous investigations. The data (both experimental and theoretical) are scattered and, still, no consensus has been reached on the number and position of water molecules, and the energetics of the hydration/dehydration of

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• , hydrogen bonds are detected between the amide protons and H6 of 1 and the chloride ions of the guest (H···Cl distance: 2.48, 2.77 and 2.90 Å). Consequently, the electrostatic interaction and hydrogen bonds are the main driving forces for the host–guest complex. It is noted that the four amide protons are

• macrocycle, which make it conformationally adaptive to maximize the binding affinities. In addition, the macrocycle shows fluorescent quenching when adding the chloride metal complexes in its solution and may be used as a fluorescent sensor for the detection of these coordination complexes. Keywords: host

• –guest chemistry; macrocycles; molecular recognition; precious metal chloride complexes; Introduction Macrocyclic receptors are the major workhorses in supramolecular chemistry. Design and synthesis of new macrocyclic receptors with new properties is always attractive but is also challenging [1

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• assembly and disassembly of the AuNR could be induced by host–guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four

• –organic hybrid nanomaterials. Keywords: cyclodextrins; gold nanorods; host–guest chemistry; light-responsive materials; molecular switches; self-assembly; Introduction Metallic nanomaterials have received intense and interdisciplinary interest due to their unique optical [1], electronic [2][3] and

• aggregates can be realized more or less efficiently through various approaches based on supramolecular interactions like metal–metal and π–π interactions [11], DNA mediated [12] or by host–guest chemistry [13]. Most of these approaches require selective functionalization of the ends of the AuNR and take

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• and potential applications according to the diverse photophysical responses are provided. Keywords: calixarene; host–guest complexation; luminescent dyes; macrocycles; photophysical properties; Introduction Fluorescence sensing represents a powerful detection methodology due to its low cost, ease of

• with carboxylated bipyridyl ligands (Ru(dcbpy)3), were screened as model guests on account of the desired strong host–guest binding affinity (Scheme 2). Fl, EY, RB, TPPS and AlPcS4 were employed as classical aggregation-caused quenching (ACQ) dyes; 2,6-TNS and 1,8-ANS were selected as intramolecular

• with substrates, typically oxygen, to produce reactive oxygen species. The competitive complexation can not only be applied in diagnosis via the aforementioned IDA but also be engaged in therapy. We proposed a host–guest strategy for activatable phototheranostics termed biomarker displacement

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• , symmetrical structures, superior host–guest properties, supramolecular assembly characteristics, and versatile functionalities [11][15][16]. Carboxylatopillar[5]arene (CP[5]) is one of the most popular functional pillarenes that has been exploited in many research areas, especially in sensing and detection

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• fluorescent measurements was used allowing recording of the absorbance spectra during the laser irradiation in the perpendicular direction and immediately after the stop of irradiation. Computational details Equilibrium geometries and intermolecular interaction energies for the host–guest assemblies between

• solvent effect induced by the acetonitrile solvent environment, the equilibrium geometries of the host–guest constituents and complexes were reoptimized considering the PCM (polarizable continuum model) solvent model [31]. The so-called basis set superposition error (BSSE) was not taken into account for

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

• enables them to be effective hosts for a wide range of guest molecules including organic biscarbonyl derivatives, near-infrared dyes, acenes, precious metal halide complexes, trimethylammonium ion-pairs, and saccharides. Keywords: fluorescent dye; host–guest chemistry; hydrogen bonding; hydrophobic

• effect; macrocycles; rotaxane; supramolecular; Review 1. Introduction A large fraction of host–guest chemistry research uses macrocyclic compounds as the host molecules [1][2]. There are several reasons for this circumstance. Macrocycles are often relatively easy to synthesize and they have inherently

• (Scheme 3) [35]. The template molecule favors this step over the alternative intermolecular reaction that leads to larger oligomers. The poor solubility of A prevents the traditional host–guest affinity measurements; however, the [2]rotaxane yield is a useful indicator of template affinity for the

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• engineering [6], energy storage [7], biosensors [8], catalysis [9], and environmental engineering [10]. Various supramolecular host molecules such as cyclodextrins (CDs), calix[n]arenes, and pillar[n]arenes can form host–guest inclusion complexes (ICs) with numerous compounds due to their unique cavity

• expected that CB[7] molecules in the nanofibers have free cavities, able to an effective capture of target molecules from the surroundings through the formation of host–guest complexes. As collected in Table S2 (Supporting Information File 1), the melting enthalpy and crystallization enthalpy of neat PCL