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

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• guest inclusion in solution. Keywords: capsule; dimeric assemblies; halogen bonding; host–guest chemistry; resorcinarene salts; X-ray crystallography; Introduction The construction of specific supramolecular assemblies based on the directional non-covalent bonding has been a central goal of

• yellow cloud. (a) The halogen bonding (blue broken lines), hydrogen bonding (red broken lines) and the host–guest effect (water molecules in CPK, and the cavity space in transparent yellow cloud) in Water@2&DIOFB; (b) The halogen bonded polymer. Water molecules in CPK mode and all the other in ball-and

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• subcomponent self-assembly of a rigid aromatic linear bisamine, pyridine-2-carboxaldehyde and Fe(II) resulting in the tetrahedral [M4L6]4− cage 25 in water reported by Nitschke [82] was a milestone of supramolecular tetrahedral complex chemistry (Figure 14). The authors have thoroughly explored the host–guest

• (Figure 21a). However, 1,8-dipyridylnaphthalene was used as hydrogen-bond acceptor for the [2 + 2] cycloaddition of fumaric acid derivatives (Figure 21b). In 2017 Purse and co-workers reported the host–guest chemistry of pyrogallo[4]arene (39) hexamers under mechano-milling conditions [94]. A hexameric

• capsule 40 formed through hydrogen-bonding and the cavity was found to be able to encapsulate different organic molecules such as alkanes, acids, amines, etc. The encapsulation of a [2.2]paracyclophane in the cage was achieved by ball milling at 30 Hz (Figure 22) and the host–guest product 40 was verified

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• complexes [2]. CD derivatives have been increasingly applied in catalysis and biomimetic reactions [3][4] thanks to host–guest interactions and to the non-toxic, chiral skeleton of CDs. More specifically, CDs applied in reactions involving metal catalysis [5], organocatalysis [6] and artificial enzymes [7

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• -difunctionalization; regioselectivity; Introduction Cyclodextrins (CDs) are cyclic oligomers of α-D-glucopyranose (Figure 1 illustrates the heptamer, β-CD) that have attracted worldwide interest in various fields of applied supramolecular chemistry due to their ability to form host–guest inclusion complexes [1]. A

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

• (Figure 1c) through host–guest interactions [61]. Chung and co-workers used a PEG-tethered adamantyl ligand for various metathesis reactions in water and DCM [62]. The authors showed that the catalyst can be easily removed by generating a host–guest complex between silica-grafted β-cyclodextrin and the

• through host–guest interaction with silica-gel-supported β-cyclodextrin. Selection of artificial metathases reported by Ward and co-workers (ArM 1 based on biotin–(strept)avidin technology and ArM 2 based on dative anchoring to hCAII). Artificial metathase based on covalent anchoring approach. α

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• supramolecular fiber materials composed of cyclodextrin (CD)–fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. We believe such a concept could be expanded to diverse host–guest complexes

• functionalize such fibers is to use host–guest inclusion complexes in CD electrospinning. To date, Uyar and Celebioglu have reported electrospinning of two different inclusion complexes: hydroxypropyl-β-CD (HP-β-CD)–tricosan [16] and HP-β-CD–azobenzene inclusion complexes [17]. Although such complexes are

•  3e). In addition, the UV–vis intensity increases with increasing C60 concentrations. This technique can disperse C60 easily to aggregate in a γ-CD fiber matrix, producing supramolecular host–guest solid fiber materials with molecularly dispersed C60. However, it is not easy to demonstrate the

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

• Iveta Tichá,
• Gábor Benkovics,
• Milo Malanga and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

• ; heterobifunctionalized alpha-cyclodextrin; homobifunctionalized alpha-cyclodextrin; regioisomers; regioselectivity; Introduction Cyclodextrins, cyclic cone-shaped oligosaccharides [1], have long attracted interest for their properties in host–guest complexes both in research and in pharmaceutical and food industry

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• [47][48][49][50][51] and host–guest chemistry [52][53][54][55][56] among others. The cardinal prerequisites to obtain these self-assembled supramolecular architectures include stoichiometry and conformational complementarity on the binding sites of the building blocks [57][58][59][60][61]. However

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• = (2.29 ± 0.27) × 106 M−1) is 3.9 times larger than that of P (Ka = (5.87 ± 0.24) × 105 M−1). Keywords: berberine; biphenarenes; host–guest complexes; molecular recognition; palmatine; Introduction Host–guest chemistry in water is significantly important due to its extensive applications in biology

• specific structures and interesting host–guest properties [21][22][23][24][25][26][27][28][29][30][31][32]. Water-soluble pillar[n]arene derivatives, especially those containing carboxylato moieties, showed low cell toxicity and good biocompatibility, and have been applied in biomedical applications such

• as bioimaging and self-assembled drug delivery systems [33][34][35][36][37][38][39][40]. For example, our group demonstrated a direct host–guest complexation-based drug delivery system for oxaliplatin by carboxylatopillar[6]arene [36]. The encapsulation could not only improve the drug‘s stability in

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

• Anthony Wishard and
• Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

• regards to the former, we have shown how poorly solvated anions such as SCN− have an affinity for non-polar surfaces. Because of this, they can compete with the interactions between two non-polar surfaces in a host–guest complexation event and can induce an apparent weakening of the hydrophobic effect

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

• first TTF-based pseudorotaxane was reported by Stoddart and Williams in 1991 (Figure 5) [33]. At this time, they investigated the host–guest properties of the π-electron-poor cyclophane cyclobis(paraquat-p-phenylene) (3) in form of the tetrakis(hexafluorophosphate) salt [58]. The square-shaped host

• breakthroughs for the construction of TTF-based supramolecular architectures: (b) Stepwise deprotection/alkylation, (c) phosphite-mediated heterocoupling, and (d) pyrrolo-annulated TTF derivatives I and J. (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their

• corresponding association constants in CH3CN. (b) Crystal structure of host–guest complex 13 [33]. Solvent molecules and counterions are omitted for clarity. TTF complexes with different host molecules. Stable TTF (a) radical-cation and (b) mixed-valence dimers in confined molecular spaces. A “three-pole

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• +) containing intermediate compound 5 were assembled in dichloromethane through host–guest interaction and capped with compound 8 under Cu(I)-catalyzed azide–alkyne cycloaddition to get the final [2]rotaxane with two distinguishable recognition sites. The target [2]rotaxane R1 was then characterized by 1H NMR