Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• in their sequestration abilities (as accounted for by the percent of sequestered guest) on varying the pH value of the solvent medium. However, these data deserve detailed discussion, even in comparison with the results obtained in our previous work. For instance, the inclusion of neutral p

• -nitroaniline guests 6, 8 and 9 shows only a fair dependence on pH. By contrast, inclusion of the charged guests 7 and 10 presents remarkable variations with pH, which are not mirrored by analogous non-aminated calixarene polymers examined in our previous work [22]. More in detail, inclusion of anionic 7

• decreases on increasing the pH, clearly indicating that inclusion is favorably affected by the presence of positive charges on the polymer network due to protonation of amine basic sites. Consistently, the behavior of the diamine derivative 10 is reversed (inclusion decreases on decreasing the pH). A

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• to 11033 Da and polydispersity index (PDI) = 1.5. Ring-opening metathesis polymerization (ROMP) of POSS-functionalized monomers The chemistry of inorganic–organic hybrid materials has emerged as a fascinating new field of modern nanotechnology. The inclusion of POSS cages into the polymeric material

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• superposition of the structures of model B and model C reveals that inclusion of the water molecule causes also a slight movement of the thiazolium ring of the cofactor towards the interior of the active site cavity (see Supporting Information File 1). Energetically, we note that the IP state is destabilized

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

• promising as an approach for fiber functionalization, the scope is limited to cases with 1:1 inclusion complexes and chemically modified CD. Fullerenes have been widely studied in the fields of chemistry and materials science because they have attractive chemical structures and good electron acceptor

Dispersion interactions

• Peter R. Schreiner

Beilstein J. Org. Chem. 2018, 14, 3076–3077, doi:10.3762/bjoc.14.286

• ) approaches largely lacked the inclusion of LD. The often very good results of standard DFT implementations in the description of chemical reactions can in part be traced back to the compensating effects of neglecting both dispersion and solvation. This is not to say that dispersion vanishes [7] in solution

Dispersion-mediated steering of organic adsorbates on a precovered silicon surface

• Lisa Pecher,
• Sebastian Schmidt and
• Ralf Tonner

Beilstein J. Org. Chem. 2018, 14, 2715–2721, doi:10.3762/bjoc.14.249

• the neighbouring adsorption site. This helps in understanding the nonstatistical pattern formation for this surface–adsorbate system and hints toward an inclusion of dispersion attraction as another determining factor for surface adsorption. Keywords: bonding analysis; cyclooctyne; density functional

A challenging redox neutral Cp*Co(III)-catalysed alkylation of acetanilides with 3-buten-2-one: synthesis and key insights into the mechanism through DFT calculations

• Andrew Kenny,
• Alba Pisarello,
• Arron Bird,
• Paula G. Chirila,
• Alex Hamilton and
• Christopher J. Whiteoak

Beilstein J. Org. Chem. 2018, 14, 2366–2374, doi:10.3762/bjoc.14.212

• optimisation led to the inclusion of an increased catalyst loading (20 mol %) and change of solvent/base, which resulted in a synthetically useful yield of the coupling product 2a (58%; Scheme 2b). This need for increased catalyst loading was also previously reported by Kanai and Matsunaga for the alkenylation

• Cp*Rh(III)-catalysed coupling of allylic alcohols reported by Jiang and co-workers which requires the inclusion of 2.0 equivalents of Cu(OAc)2 for the same products [21]. With the optimised conditions in hand, the potential scope/limitations of the catalytic protocol were studied (Scheme 3

• ). Pleasingly, acetanilides with both electron-donating (1b–d) and electron-withdrawing substituents (1e–g) could be converted in yields of between 39-67%. The lower yields of some of these conversions highlight the challenging nature of this coupling. Thereafter, regioselectivity was studied by the inclusion

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

• 1H NMR spectroscopy in aqueous phosphate buffer solution (pH 7.4). In the presence of 2,2’-CBP4, 1H NMR signals of P and B displayed very large upfield shifts, indicating the formation of inclusion complexes with strong binding affinities. Fluorescence titration experiments showed that P and B

• compared with the free guest. Especially, the chemical shifts for the middle protons, H1–6, and H10–11, are larger than those for the ending H7–9. These results indicate that berberine was engulfed by the cavity of 2,2’-CBP4 to form a pseudorotaxane-type inclusion complex. Similar complexation-induced NMR

• changes were observed for the host–guest mixture of P and 2,2’-CBP4 (Supporting Information File 1, Figure S9), suggesting a similar binding mode of an inclusion complex. The host–guest encapsulation was then confirmed by 2D NOESY experiments, as shown in Figures S10 and S11, Supporting Information File 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

• derivatives I and J [55][56][57]. The incorporation of these symmetric species into MIMs often circumvents complex isomeric mixtures. 3. Pseudorotaxanes and inclusion complexes: on the way to TTF-based MIMs Pseudorotaxanes have the general form of a molecular thread encircled by a macrocycle. The difference

• rotaxanes is achieved by stoppering reactions, while catenanes can be made by macrocyclization of the pseudorotaxane thread. Therefore, we discuss in the following section reports of important pseudorotaxanes and inclusion complexes that contributed to major developments of TTF-based MIMs and AMMs. The

• , extended π-surfaces [64] of TTF derivatives can have a stabilizing effect upon complexation. TTF (1) also forms inclusion complexes with neutral host molecules such as cyclodextrins (Figure 6). This complexation is mainly driven by the hydrophobic effect. α-Cyclodextrin (6) molecules encapsulate the

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• epoxides’ opening by nucleophiles can therefore act as a competing side reaction in many coupling processes with the inclusion of graphene-family materials [9][16]. In other words, opening graphene-family material’s epoxides should be taken into account even when the crosslinker-based amidation or

• properties of these materials can thus be tuned, and the introduced functional groups can be utilized for further reactions [9][17][18][19]. The literature features many examples of amide- or ester-bond formation with the inclusion of graphene-family materials [20][21]. However, some of the reported

• the epoxides of the graphene-family material. In a coupling with the inclusion of graphene-family material and amine hydrohalide some reactions or transformations may occur, but they are based on electrostatic adsorption or hydrogen bonding [23], rather than on covalent modification. If formation of

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• , or the design of self-inclusion complexes, in which an outer cavity-attached rhodamine was intramolecularly bound in the CB7 cavity. As an alternative, it has been previously suggested that host-assisted protonation of a cavity-binding functional moiety (an “anchor group”) and a suitably attached

• cm2 s−1) [60][65]. This gave D = 4.87 × 10−6 cm2 s−1 for 2 and D = 3.39 × 10−6 cm2 s−1 for the 2•CB7 complex, which perfectly matches the range reported for other dyes and their respective CB7 complexes [60]. In accordance with inclusion of the anchor group into the CB7 cavity and thus exclusion

Recent advances in materials for organic light emitting diodes

• Eli Zysman-Colman

Beilstein J. Org. Chem. 2018, 14, 1944–1945, doi:10.3762/bjoc.14.168

• Organic Chemistry covers novel phosphorescent and TADF materials design and their inclusion as emitters in OLEDs. Some highlights in this issue include the work of Thanh-Tuân Bui et al., who provide a welcome perspective on blue TADF materials for OLEDs in the form of a review article [2]. Cristina

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

• alkyl chain rings, and formed a self-inclusion structure in aqueous media, which was assigned as a pseudo[1]catenane structure. The hydrophobic chain ring was hidden inside the pillar[5]arene cavity in the pseudo[1]catenane structure, thus the bicyclic compound was soluble in water at 20 °C with a

• /hydrophilic ratio. In this study, we successfully induced an LCST change using a neutral guest and a new pillar[5]arene derivative. We synthesized a new bicyclic compound consisting of an amphiphilic pillar[5]arene and hydrophobic alkyl chain rings 3 (Figure 1b). This bicyclic compound formed a self-inclusion

• then demonstrated a chemically responsive transmittance change using the supramolecular structural change. An aqueous solution containing 3 at 20 °C was clear (Figure 4a) as the clouding point of the self-inclusion structure 3 is 24 °C. Upon addition of the neutral guest 1,4-dicyanobutane, the solution

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• Scheme 1. The secondary amines are designed to form ammoniums that will strongly bind to CB[6] through ion-dipole interactions under aqueous acidic conditions. Upon formation of the inclusion complex with CB[6], the azide and alkyne functionalities inside the CB[6] cavity will be placed in close

• formed that indicated CB[6] dissolution and formation of the inclusion complex. One equivalent of DN-CC was added and the mixture was further heated at 70 °C. LC–MS analysis of the reaction mixture showed that the building blocks were completely consumed after one hour of heating, and that the crude

• interactions are preserved under the MS conditions. Inclusion of the triazole in the CB[6] cavity was evidenced by the upfield shifted triazole resonance from 8.5 ppm to 6.4 ppm when compared with that of free triazole in non-interlocked system [22][24][25]. NOE cross peaks between the triazole and CB[6

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• . Optimization of these binding interactions could lead to the development of highly potent CSP-based QS modulators while the inclusion of non-natural amino acids within the CSP sequence would confer resistance to protease degradation, a requirement for drug candidates. Keywords: binding surface; competence

Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

• Rakesh Puttreddy,
• Ngong Kodiah Beyeh,
• S. Maryamdokht Taimoory,
• Daniel Meister,
• John F. Trant and
• Kari Rissanen

Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146

• 1H NMR spectroscopy. In the solid state, of the nine obtained X-ray crystal structures, eight were consistent with the formation of BrC6-N-oxide endo complexes. The lone exception was from the association between 4-phenylpyridine N-oxide and BrC6, in that case the host forms a self-inclusion complex

• ) contacts between guest C3 hydrogens and the host carbon/hydroxy oxygens, respectively. From our experience, the lack of π-acidic aromatic protons in guest 10 usually results in exo complexes [36][37][39]. To our surprise, 10+BrC6 forms a self-inclusion complex of BrC6 by itself as shown in Figure 2g, the

• property usually preferred by resorcinarenes when solvate and guest molecules are absent inside the cavity. Note that the self-inclusion complex of BrC6 has exo methanol solvent hydrogen bonds to host hydroxy groups. This can possibly be explained by the longer lower-rim hexyl chains providing enough

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

• interested in the inclusion of 4-aminophenol, playing the role of peripheral unit, in G-0-2 dendritic melamines’ preparation, by applying the classic SN2-Ar amination of cyanuric chloride in iterative-convergent strategies. Depending on several factors such as (i) the variable π-deficiency of the s-triazine

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• -ray crystal structure of free ZB4 shows it to exist as a self-inclusion conformation in the solid state (Figure 1a). This conformation is different from the ones containing different lower-rim alkyl groups reported earlier [37][38]. Crystals were obtained by slow evaporation of the compounds’ CH3CN

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• substrates, indeed, have been considered a class of probe guests of choice for investigating the formation of host–guest inclusion complexes with cyclodextrins [38][39][40][41] and calixresorcinarenes [42], because of both their easy accessibility and the fact that their molecular properties can be largely

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• results clearly confirmed the cooperative effect and special role of the calixarene backbone. Aldol reaction Since chiral substituents and binding sites attached to the upper rim of the calixarene backbone can offer the full advantage of the unique inclusion properties of hydrophobic cavity, Wang et al

A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds

• Claudia Lar,
• Adrian Woiczechowski-Pop,
• Attila Bende,
• Ioana Georgeta Grosu,
• Natalia Miklášová,
• Elena Bogdan,
• Niculina Daniela Hădade,
• Anamaria Terec and
• Ion Grosu

Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115

• . Accordingly, a further constrained geometry optimization was performed for the cryptand–anthracene case, where the distance between the 3,5-dicyanopyridine fragment of 2 and the carbon atom of the anthracene was kept constant for each optimization case. The inclusion dynamics of the anthracene in the cavity

• the host and guest molecules should overcome the magnitude of the deformation potential during the inclusion process. Experimental Computational details: The equilibrium geometries and the intermolecular interaction energies for different host–guest assemblies between the cryptand 2 and pyrene

• of the cryptand–anthracene (a) and cryptand–pyrene (b) host–guest complexes. The equilibrium geometry structure of the cryptand 2–1,5-dihydroxynaphthalene host–guest complex. The inclusion dynamics of the anthracene in the cavity of the cryptand for different constrained distances (blue < green < red

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• : specifically, solid solutions, cocrystals, polymorph transitions, carbon nanotube dissolution and inclusion complex formation. Keywords: DNA; green chemistry; mechanochemistry; nucleoside; nucleotide; Introduction Several definitions of mechanochemistry have been attempted since Ostwald included it as one of

• carbon nanotubes [93]. In the presence of guanosine-5′-monophosphate, 78% of the SWNT (0.78 mg mL−1) was dissolved but attempted removal of iron contamination from this material by treatment with acid gave a "viscous precipitate". Formation of cyclodextrin–drug inclusion complexes can be accelerated

Local energy decomposition analysis of hydrogen-bonded dimers within a domain-based pair natural orbital coupled cluster study

• Ahmet Altun,
• Frank Neese and
• Giovanni Bistoni

Beilstein J. Org. Chem. 2018, 14, 919–929, doi:10.3762/bjoc.14.79

• the water dimer calculated previously at the CCSD(T)/CBS level (−5.01 kcal/mol [68]) agrees remarkably well with the present DLPNO-CCSD(T) result (ΔEe = −4.95 kcal/mol, Table 1). The accurate calculation of ZPE correction of H-bonded systems requires larger basis sets and the inclusion of anharmonic

• dimerization energies range from −4.51 kcal/mol (Conf1) to −3.52 kcal/mol (Conf3). Therefore, the conformers of both dimers lie within 2 kcal/mol. The inclusion of the ZPE correction to relative energies, which amounts up to 0.7 kcal/mol, makes the energetic separation between the conformers even smaller

• typically of the same order of the overall . Electron correlation also affects the energetic separation of various conformers. For example HF predicts a large energetic separation between Conf2 and Conf3 for both water and HF dimers (about 0.6 kcal/mol) whilst the inclusion of electron correlation makes

Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies

• Elias Christoforides,
• Andreas Papaioannou and
• Kostas Bethanis

Beilstein J. Org. Chem. 2018, 14, 838–848, doi:10.3762/bjoc.14.69

• dairy products has been studied thoroughly in recent years. Although the physicochemical characterization of the inclusion compound of cholesterol in β-CD has been achieved by various methods, no crystal structure has been determined so far. We report here the crystal structure of the inclusion compound

• of cholesterol in β-CD. The inclusion complex crystallizes in the triclinic space group P1 forming head-to-head dimers which are stacked along the c-axis. One well-defined cholesterol molecule ‘axially’ encapsulated inside the β-CD dimer and 22 water molecules that stabilize the complexes in the

• inclusion compound remains very stable in aqueous solution at both temperatures. Keywords: beta-cyclodextrin; cholesterol; crystal structure; molecular dynamics; Introduction Cholesterol ((3β)-cholest-5-en-3-ol, CHL, Figure 1a) is a polycyclic steroid that is synthesized in mammalian cells and has a

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• that they form any type of inclusion complexes disturbing the recognition of ATP. Association constant determination The association constant has been obtained from the emission spectra using standard methods for non-linear curve fitting [65]. The best fit was obtained using 1:1 stoichiometry which