Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• [41][42][43][44][45], this indicates the occurrence of severer and severer dynamic-conformational changes upon complex formation. Therefore, we can conclude that the overall bell-shaped trend for K1 values on passing from CAP−1 to CAP−4 is the outcome of a fine interplay between favourable

• complex formation. Interestingly, a fair upfield shift is observed also for the signals at 0.82 and 1.14 ppm (passing to 0.71 and 1.03 ppm, respectively) relevant to the propyl pendant groups linked at the 2, 8, 14 and 20 positions of the calixarene scaffold. Assuming for CAP the occurrence of an “all

• occurring in host–guest complex formation processes involving calixarenes in general. This can be particularly useful, even because CAP and structurally related ligands might find various interesting applications, due to their amphiphilic character, chirality and coordination ability towards metal cations

Metal-mediated base pairs in parallel-stranded DNA

• Jens Müller

Beilstein J. Org. Chem. 2017, 13, 2671–2681, doi:10.3762/bjoc.13.265

• glycosidic bonds, parallel-stranded duplexes have been investigated. In many cases, such as the well-established cytosine–Ag(I)–cytosine base pair, metal complex formation is more stabilizing in parallel-stranded DNA than in antiparallel-stranded DNA. This review presents an overview of all metal-mediated

Structural diversity in the host–guest complexes of the antifolate pemetrexed with native cyclodextrins: gas phase, solution and solid state studies

• Magdalena Ceborska,
• Magdalena Zimnicka,
• Aneta Aniela Kowalska,
• Kajetan Dąbrowa and
• Barbara Repeć

Beilstein J. Org. Chem. 2017, 13, 2252–2263, doi:10.3762/bjoc.13.222

• methods – FTIR–ATR and Raman were used for describing the way of PTX-CD interactions. The IR spectroscopy in the region characteristic for δ-HOH bending of water molecules attached to CDs (1600–1700 cm−1) is usually employed for tracking of the inclusion complex formation, however, Raman spectra of this

• identification of guest–host interactions is possible [17][18]. Any changes in the band position as well as increasing or decreasing of its intensity indicate complex formation. In that sense Raman spectroscopy emerges as an important technique for studying host–guest interactions, in particular for verifying if

• affinity toward PTX (Ka = 4 M−1). Findings from FTIR–ATR and Raman experiments demonstrate that the region of C=C bond vibrations of the guest is an excellent indicator of complex formation. The observed changes in this band (position and intensity), together with the information about possible appearance

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• complexes with paraquats 8–10. Nevertheless, we have demonstrated qualitatively the complex formation of 6@8–6@10 by FAB–MS (Figures S43-S45, Supporting Information File 1). There are no hydrogen bonds between the protons of the terminal hydroxy groups and oxygen atoms in the complex of clip 2 with guest 8

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• p-tert-butylthiacalix[4]arene 4 is also of interest because this fragment contains a polar NH group able to interact with anionic substrates and a chromophore fragment necessary for the spectrophotometric detection of the complex formation. In this regard, the alkylation of monosubstituted

• hindrances to the complex formation. Review of literature data [62][63][64][65] indicate a good agreement between the results of calculations involving the complexes geometry determined by this method and experimental data. The PM3 method is used quite productively for molecular design and modeling of the

Influence of the milling parameters on the nucleophilic substitution reaction of activated β-cyclodextrins

• László Jicsinszky,
• Kata Tuza,
• Giancarlo Cravotto,
• Andrea Porcheddu,
• Francesco Delogu and
• Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 1893–1899, doi:10.3762/bjoc.13.184

• findings lend support to the idea that mechanical activation can induce chemical reactivity [29] and selectivity [30] which is different to that observed in solution, which can be further complicated by the inclusion complex formation property of cyclodextrins. How exactly the milling parameters influence

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• crystals. The disagreement between solution and crystal structure in terms of complex formation and orientation/conformation of the guest indicates that the lattice forces and organization in the crystal prevail by far over the soft host–guest contacts established in solution and determines the final

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• –solvent charge-transfer complex formation. Keywords: aryldiazonium salts; borylation; eosin Y; mechanochemistry; photocatalysis; Introduction The use of mechanical force to process materials or to induce chemical transformations is perhaps as old as the history of mankind itself [1]. Similarly, from

One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• hydrophobic interaction, as the driving force of complex formation, the threading of the CDs is only achievable in aqueous solution, but the hydrogen bonds between the hydroxy groups impede the water solubility of the products. Thus, the stoppering reaction is mostly limited to organic solutes, in which

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• it via noncovalent interactions. Figure 2 shows three different channels in a minimal replicating system. Building blocks A and B can react via the bimolecular reaction pathway, to form the template molecule T. In the second pathway – binary complex formation – A and B bind together reversibly to

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• end groups were prepared starting from diacetylene-modified cyclodextrin monomers by a combined Glaser coupling/click chemistry approach. Structural perfection of the neutral CD polymers and inclusion complex formation with ditopic and monotopic guest molecules were proven by MALDI–TOF and UV–vis

Inclusion complexes of β-cyclodextrin with tricyclic drugs: an X-ray diffraction, NMR and molecular dynamics study

• Franca Castiglione,
• Fabio Ganazzoli,
• Luciana Malpezzi,
• Andrea Mele,
• Walter Panzeri and
• Giuseppina Raffaini

Beilstein J. Org. Chem. 2017, 13, 714–719, doi:10.3762/bjoc.13.70

• finally optimized up to an energy gradient lower than 4 × 10−3 kJ mol−1 Å−1. The simulation protocol closely followed the strategy proposed by some of us for modeling the inclusion complex formation without any a priori assumption about its possible geometry [17][18][19][20][21]. Thus, the optimized

• single bond. The lack of disorder in the C9–C10 segment suggests that complexation constrains 2 in a single conformation in the solid state. The MD simulations led to the formation of a 1:1 inclusion complex of β-CD with molecules 1 and 2 both in vacuo and in explicit water. In both cases, the complex

• formation was relatively fast, and allowed us to find the most stable geometry eventually achieved from the trial starting arrangements [17] mentioned in the Materials and Methods section. The most stable complex yielded inclusion of an aromatic ring in the β-CD, with the seven-membered ring, the side chain

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• determined for deoxycholic acid derived ligand 5d. Thus, there is no appreciable dependence between the value of the binding constants and the presence of an extra hydroxy group in the cholane fragment. To the best of our knowledge a complex formation of 1,8-diaminoanthraquinone derivatives with Al and Cr

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• in Figures S11 and S12 (Supporting Information File 1). The titration experiments of R2 with sodium salts of F− and AcO− ions revealed redshifts to 556 nm and 559 nm correspondingly with clear isosbestic points indicating complex formation. The titration profiles of R2 obtained by the addition of

• band at higher wavelength confirms the complex formation process. The HOMOs and LUMOs of R1–F− and R1–AcO− are represented in Figure 19 and Figure 20; the HOMOs and LUMOs of R2–F− and R2–AcO− are represented in Figure 21 and Figure 22. The decrease in the bond length value corresponding to the OH group

• in its original form. A significant hyperchromic effect is observed for the band at 477 nm when In 2 (F−) is in the ‘ON’ mode, i.e., during the R1–F− complex formation process. With the introduction of Hg2+ (In 3), the output attains the zero state (‘OFF’). In total, three input combinations lead to

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• a complex formation, namely a hypochromic effect and red shift of the absorption as well as fluorescence quenching upon addition of the host (Figure 6 and Supporting Information File 1, Figure S3). Furthermore, the significant line broadening of the absorption bands occurs most likely due to

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• by exploiting the pores of the polymer network to encapsulate the guest molecules. However, it should be stressed that CD nanosponges similar to ours and prepared by using citric acid as cross-linker, showed a different behaviour towards ibuprofen: the authors provided evidence of inclusion complex

• formation as the main mechanism of absorption [33]. We may conclude that the type of monomer and the cross-linker agent both play a key role in driving the absorption towards inclusion complexes or segregation in the polymer pores, although a sufficient number of data is still missing to formulate a general

Synthesis of multi-lactose-appended β-cyclodextrin and its cholesterol-lowering effects in Niemann–Pick type C disease-like HepG2 cells

• Keiichi Motoyama,
• Rena Nishiyama,
• Yuki Maeda,
• Taishi Higashi,
• Yoichi Ishitsuka,
• Yuki Kondo,
• Tetsumi Irie,
• Takumi Era and
• Hidetoshi Arima

Beilstein J. Org. Chem. 2017, 13, 10–18, doi:10.3762/bjoc.13.2

• , and bioavailability of drugs. CDs improve the above properties of drugs through complex formation, when formulated as injectable solutions, sprays, eye drops, powders, and tablets [7][8]. In recent years, the efficacy of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) in the treatment of the NPC disease has

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• pollutant of emerging concern (EP), was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure of the host–guest complex. Keywords: carboxymethyl β-cyclodextrin polymer; colloid stability; ibuprofen

• bisphenol A was enhanced in aqueous solutions containing β-CD [25], while the photodecomposition of pesticides of similar structure (parathion and paraoxon) was inhibited or catalyzed, respectively, by β-CD [26]. The complex formation can either protect the drug from the effect of light or accelerate the

• in distilled water without any additives (Figure 6 and Table 4) and a slight enhancement in the degradation rate was obtained with nanoTiO2. In the presence of the polymer the rate of degradation decreased suggesting that the complex formation of ibuprofen has a protective effect. Using the CMBCD-P

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• that this is due to the ability of the StaF/X-domain complex to allow substrate reorganisation after initial complex formation has occurred. These results highlight the importance of testing different peptide/protein carrier constructs for in vitro GPA cyclisation assays and show that different Oxy

• Tris pH 7.4 and 150 mM NaCl) at room temperature for 30 min to allow complex formation to occur between StaF and Xsta. Analysis of StaF alone (MW of 47.3 kDa) resulted in overlapping peaks with absorption at λ = 280 and 415 nm at an elution volume of 13.1 mL, whereas when Xsta alone (MW of 53.2 kDa

• this complex allows substrate reorganisation after initial complex formation, which ensures proper substrate orientation in the active site. These results highlight the importance of testing different peptide/protein carrier constructs for in vitro GPA cyclisation assays and show that different Oxy

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• cavity of this molecule is too small to accommodate DNA base pairs. All these results support the work of Hoffmann and Bock who examined the complex formation between different CDs and nucleotides [107]. In contrast, in a more recent work, Jaffer et al. have found that α-CD can form H-bonds with DNA base

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• transfer agent (CTA) that has α-cyclodextrin (α-CD) as a host molecule (α-CD-CTA). Prior to the polymerization of N,N-dimethylacrylamide (DMA), we investigated the complex formation of α-CD with DMA. Single X-ray analysis demonstrated that α-CD includes DMA inside its cavity. When DMA was polymerized in

• have been used in the hydrolysis of activated esters [16][17][18][19] and as phase-transfer catalysts [20][21][22][23][24][25][26][27][28]. Moreover, via complex formation, modern supramolecular catalysts [29][30][31][32][33] have been used to achieve various highly efficient and selective reactions

• to studying the polymerization of vinyl monomers, we investigated the complex formation of CDs with vinyl monomers. When mixing α-CD and DMA, we obtained single crystals suitable for X-ray crystallography analysis. The X-ray crystallography analysis is important to understand the complex in the

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• poorly soluble in water: the precipitate formed upon acidification by HCl, was filtered and the solid was re-dissolved in the equivalent amount of base. But, it is also true, that complex formation between the MPA and the product, particularly in case of the β-CD version, pointed out that pharmaceutical

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• in DPV experiment only the higher value of the anodic peak was observed. For the negative region, there is no counter peak in the 1.0 V to 0.0 V potential ranges. Reactivity towards Hg2+ and Cd2+ complex formation The 2,2′:6′,2″-terpyridine derivatives are known to form stable complexes with

• the possible formation of weak hydrogen bonds in this solvent [44]. For both metal ions similar absorption features were observed. Upon addition of HgCl2 solution, the absorption maxima located at 378 nm and 431 nm are merging into a new band at 421 nm upon mercury complex formation. A progressive

• that a 2:1 complex is formed. The straight slope and its saturation at a ratio of 0.5 indicate a high binding constant which cannot be determined from this set of data. To assess the terpyridine-metal complex formation, 1H NMR titration of 4a with HgCl2 has been performed. The addition of 0.25

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• peak of aromatic ring hydrogen atoms (Hc, resonated at 7.35 ppm) was converted to two distinct peaks at 7.20 and 6.95 ppm (Hc1, Hc2). In addition, signals belonging to the fluorene moieties and tert-butyl groups, which are quite far away from binding site, were also affected by complex formation. For

• during the complex formation. The fact that receptor L shows a sensitive recognition affinity to copper ions and a much more obvious shift of 1H NMR peaks in the presence of Cu2+ is actually not surprising because of a relatively rigid binding pocket of receptor L providing four sites of NH and OH which

• allows a suitable complex formation with a copper ion (Scheme 3). To show the high selectivity of chemosensor L for copper ions, the association constant and limit of detection (LOD) were compared with those reported for other related chemosensors (Table 1). It should be emphasized that due to different

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• , the extra methylene group of butane meant that it bound to the host twelve times more strongly than propane, and this allowed selective butane complex formation from a 1:1 propane–butane mixture (Figure 12). In short, aqueous solutions can be used to separate gases; to paraphrase Cram, the synthesis