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

• , Hungary 10.3762/bjoc.12.286 Abstract Advanced oxidation processes (AOPs) are considered highly competitive water treatment technologies for the removal of organic pollutants. Among AOP techniques, photocatalysis has recently been the most widely studied. Our aims were to investigate how the dispersion of

• start to aggregate and form larger particles enhancing the turbidity of dispersion. The turbidity (the haziness of the dispersion caused by particles invisible for the naked eye) was measured to monitor the aggregation of the particles of nanoTiO2. Various monomer and polymer CD derivatives were studied

• while the polymers showed stabilizing effect (Table 1). The effects of the polymer concentration (1% and 5%) and its average molecular weight (90 kDa, 200 kDa, 300 kDa) on the colloidal stability of the nanoTiO2 dispersion were also studied using the neutral HPBCD-P. It was clearly shown that the

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• solution in a round bottom flask. Hydration and extrusion with a Liposofast extruder and membranes with 100 nm pore size yield bilayer vesicles of an approximate size of 100 nm. CDVs were decorated with AdSq by simple addition of the AdSq to the aqueous dispersion of the CDVs. Interestingly, the

• any influence on solubility of AdSq, stability of CDVs or host guest interaction can be neglected. Fluorescence spectra were taken 20 min after addition of AdSq to assure the complete equilibration of the CDV dispersion. The fluorescence spectrum of AdSq without CDV shows no fluorescence, while

• investigated the photochemistry of AdSq on CDV. To this end, AdSq was added to an aqueous dispersion of CDV exactly as described above. The solution was irradiated for 600 s and absorption spectra were taken at various time points. As shown before in the acetonitrile solution, also AdSq immobilized on CDV

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• at the B3LYP/Def2-TZVP level of theory combined with D3BJ dispersion correction. The reactions of benzonitrile oxide with both E- and Z-imidazolyl enamines have been shown to proceed stereoselectively to form trans- and cis-isoxazolines, respectively. The preference of E-isomers over Z-isomers

• ][40][41][42] theory level. Grimme’s D3BJ dispersion correction [43][44] was applied to improve the long range interactions related calculation accuracy [45]. To the best of our knowledge there is not a high level of theoretical investigations reported on the possible reaction pathways of nitrile

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

• the hydrogen bonding destruction increases the solubility of poorly soluble CD derivatives. Wetting the solid dispersion with water and 50% EtOH resulted in not only lower temperature but practically no reaction was experienced as confirmed by the lack of azide in the IR spectrum of the isolated solid

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• and overlap, density functional theory (DFT) calculations were performed. Geometry optimization and molecular orbital surfaces were determined and are shown in Figure 11. Geometries of the BXR series were obtained at the D2 dispersion corrected B3LYP/6-311G(d,p) level of theory. Subsequent time

Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

• Reji Thomas and
• Nobuyuki Tamaoki

Beilstein J. Org. Chem. 2016, 12, 2211–2215, doi:10.3762/bjoc.12.212

• Bijvoet pairs [39]. However, the requirement of heavy atoms for the better anomalous dispersion, limits the usage of X-ray diffraction in determining the absolute stereostructure. In many of the molecules, the requirement of a heavy atom leads either to functionalization of the molecules with groups

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• ) catalysts are achieved by the dispersion of liquid organic salts on highly porous materials, amongst which montmorillonite clays, modified silica, and polystyrene-based solids are the most frequently used [36][37]. Some very recent examples described the production of biodiesel via the transesterification

A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis

• Mariano Goldberg,
• Denis Sartakov,
• Jan W. Bats,
• Michael Bolte and
• Michael W. Göbel

Beilstein J. Org. Chem. 2016, 12, 1870–1876, doi:10.3762/bjoc.12.176

• us to assign the R configuration by anomalous dispersion (Supporting Information File 4). This isomer corresponds to the slower running isomer on a Chiralpak IA column. By catalytic hydrogenation with Pd on charcoal the bromo residue of enantiopure 30 was replaced with hydrogen thus converting R

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• due to the inherent properties of micro/flow reactors: high mass-transfer rates [8], spatial separation of reagent addition and mixing, high reagent dispersion, high energy efficiency, improved irradiation [9][10][11], ease of upscaling, low hazard potential and multidimensional parameter control [7

• effects on reaction rates and selectivities. Furthermore, specific properties of the reagents and solvents (viscosity, surface tension, gas solubility) will be critical to the dispersion and slug flow formation. Light source The benefit of microreaction technologies applied to photochemical processes is

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• the results presented herein, the extra stabilization of the CF3 substituted systems cannot be due to polar or charge-transfer effects but rather from dispersion interactions [27]. In an effort to prove this hypothesis, we performed an energy decomposition analysis (EDA) at the B3LYP-D3/TZ2P level

• , represents the destabilizing interactions between the occupied orbitals (steric repulsion), ΔEoi shows the interaction between orbitals (including all electron-pair bondings, HOMO–LUMO charge-transfer processes, polarization interactions, etc.), and ΔEdisp refers to the effect exerted by dispersion forces

• . As shown in Table 1 a slightly higher interaction energy was found for 7 + 8 (−7.7 kcal/mol). It is important to point out the great significance of the dispersion forces in these π-stacked complexes, representing ≈60% of the total attractive forces. Noteworthy, the distances from the centroid of the

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• anomalous dispersion corrections for the non-hydrogen atoms were taken from the International Tables for Crystallography [77]. All calculations were performed with the SHELXL-97 [78] package and the programs COLLECT [79], DIRAX [80], EVALCCD [81], SIR-92 [82], SADABS [76], ORTEP III [83] and PLATON [84

Is conformation a fundamental descriptor in QSAR? A case for halogenated anesthetics

• Maria C. Guimarães,
• Mariene H. Duarte,
• Josué M. Silla and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2016, 12, 760–768, doi:10.3762/bjoc.12.76

• possible for isoflurane. However, geometry optimization at the MP2/6-311++g(d,p) and ωB97X-D/6-311++g(d,p) (a DTF method which includes dispersion effects) levels converged to five energy minima for the gas phase, implicit solvents (cyclohexane, DMSO and water, using the polarizable continuum model), and

Versatile deprotonated NHC: C,N-bridged dinuclear iridium and rhodium complexes

• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 117–124, doi:10.3762/bjoc.12.13

• D3 dispersion term [77]. For iridium and rhodium we used the small-core, quasi-relativistic Stuttgart/Dresden (SDD) effective core potential with an associated valence contracted basis set (standard SDD keywords in Gaussian 09) [78][79][80]. The electronic configuration of the molecular systems was

Aggregation behavior of amphiphilic cyclodextrins in a nonpolar solvent: evidence of large-scale structures by atomistic molecular dynamics simulations and solution studies

• Giuseppina Raffaini,
• Fabio Ganazzoli and
• Antonino Mazzaglia

Beilstein J. Org. Chem. 2016, 12, 73–80, doi:10.3762/bjoc.12.8

• due to the number of pairwise interactions that increase their number and importance more than simply proportionally to the number of molecules. Dynamic light scattering Dynamic light scattering (DLS) measurements were carried out on SC2OH (Scheme 1B, n = 1) dispersion in nonpolar solvent (CH2Cl2

• −1 concentration. The dispersion was centrifuged at 3000 rpm (10 min) to remove dust and air bubbles. Dynamic light scattering (DLS) measurements were carried out on a homemade apparatus by using a duplicated Nd:YAG laser source (λ = 532.0 nm) at a power of 50 mW, at a scattering angle of 90°. The

• Å after an MD run of 50 ns viewed along the z-, y-, x-directions (from left to right). The flat membrane with a minor central gap is clearly seen in the central panel. RH distribution by CONTIN (and Mie scattering normalization) analysis of SC2OH dispersion (2 mg mL−1) in dichloromethane. The inset

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• antioxidants such as butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), suspected to be carcinogenic [13][14]. However, the major drawbacks for their use in food are their low aqueous solubility that limits their homogenous dispersion and their contact with pathogens [15], their susceptibility

Physical properties and biological activities of hesperetin and naringenin in complex with methylated β-cyclodextrin

• Waratchada Sangpheak,
• Jintawee Kicuntod,
• Roswitha Schuster,
• Thanyada Rungrotmongkol,
• Peter Wolschann,
• Nawee Kungwan,
• Helmut Viernstein,
• Monika Mueller and
• Piamsook Pongsawasdi

Beilstein J. Org. Chem. 2015, 11, 2763–2773, doi:10.3762/bjoc.11.297

• for analysis. The MM- and QM-PBSA/GBSA calculations were conducted to estimate the binding free energy of the inclusion complex [40][60]. For QM calculation, the single point M06-2X/6-31+G** level of theory including the empirical dispersion correction energy [46] was treated on the same set of

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• synthesis of 1·TM-βCD or 1·TM-γCD in polar protic solvents is driven by hydrophobic interactions in combination with electrostatic, van der Waals or π–π interactions. In comparison, in polar aprotic solvents such as DMF, THF relies mostly on host–guest specific interactions, such as dispersion or dipole

• atmosphere for 48 h to give a turbid dispersion. The water was removed by lyophilization and the complex, as a white powder was used for the preparation of 1·TM-βCD. The synthesis of the inclusion complex 1·TM-γCD was performed under similar experimental conditions as those used for the preparation of the 1

Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

• Giuseppina Raffaini,
• Antonino Mazzaglia and
• Fabio Ganazzoli

Beilstein J. Org. Chem. 2015, 11, 2459–2473, doi:10.3762/bjoc.11.267

• molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates

• combination of dispersion and dipolar interactions and of hydrogen bonds, adopting throughout a “bottom up” atomistic description. The modelled system consists of an amphiphilic β-CD of Scheme 1 carrying hydrophobic H groups at the primary rim (R = C2H5) and polar P groups at the secondary rim with n = 0 (R1

• the above-mentioned order, with weaker interactions among the H groups only due to dispersion forces in case a, and stronger interactions in cases b and c due to the presence of intermolecular hydrogen bonds and dipolar interactions. The subsequent MD runs of these geometries, each lasting for 30 ns

Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

• Shintaro Kawano,
• Toshiyuki Kida,
• Mitsuru Akashi,
• Hirofumi Sato,
• Motohiro Shizuma and
• Daisuke Ono

Beilstein J. Org. Chem. 2015, 11, 2355–2364, doi:10.3762/bjoc.11.257

• , which is manifested from dispersion forces (δd), polarity (δp), and hydrogen bonding forces (δh). Toluene has a relatively higher contribution in terms of δp and δh compared to n-dodecane; these parameters may result in a higher affinity for the interface of toluene and water compared to that of n

• method. The CD nanogel was labeled with fluorescein isothiocyanate (FITC) in the aqueous phase before emulsification. A Pickering emulsion was prepared by mixing the aqueous dispersion containing FITC labeled-CD nanogels (0.1 wt %) with n-dodecane (Φoil = 0.1) and subsequent shaking for 1 min. After

• water was changed twice daily. Then the aqueous dispersion was lyophilized for three days to yield a white powder as a urethane-crosslinked DM-β-CD polymer. The CD nanogel was prepared by the redispersion of the powder in distilled water with the aid of ultrasonication and stored in a refrigerator until

Co-solvation effect on the binding mode of the α-mangostin/β-cyclodextrin inclusion complex

• Chompoonut Rungnim,
• Sarunya Phunpee,
• Manaschai Kunaseth,
• Supawadee Namuangruk,
• Kanin Rungsardthong,
• Thanyada Rungrotmongkol and
• Uracha Ruktanonchai

Beilstein J. Org. Chem. 2015, 11, 2306–2317, doi:10.3762/bjoc.11.251

• on a modified linear response to treat electrostatic interactions with an empirical term treating the dispersion interactions. In this work, the ΔGsolv was considered as polar and non-polar solvation terms. The polar solvation term is evaluated from the Poisson–Boltzmann (PB) solvation method which

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• nanocomposite gels and silica solutions. In both cases, a similar power dependence, , as in Equation 1, was obtained. Therefore, similarly to the silica solution, the homogeneous dispersion of silica nanoparticles was retained in the nanocomposite gels until at least 30 wt % silica content. Viscoelastic

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

• Albert Poater and
• Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

• change the functional for the solvent calculations, despite knowing that the dispersion interactions can occur [68][69][70][71][72][73]. However, here we consider that the qualitative comparison between the set of studied catalysts and even the quantitative trends (side/bottom) should not be affected by

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• constituents of pharmaceuticals and dyestuffs, are non-trivial and involve multiple steps. Consequently, the one-pot SCPC oxidation of phenanthrene (1) to benzocoumarin (2), with a dispersion of TiO2 in aqueous, oxygenated CH3CN [29], is very appealing from a green chemistry point of view (Scheme 1). First

• in an aqueous dispersion of a Pt-TiO2 catalyst, an interesting self-reaction occurred. Ohtani and co-workers isolated modest yields of secondary amines 13 that were formed via C–N coupling (Scheme 4, top) [48]. Terminal diamines reacted by ring closure resulting in cyclic amines 14; pyrrolidine was

• standard reactions with just P25 gave a slight excess of the chromenopyrrole for most substituents, but the selectivity could be tuned to some extent by modifications to the catalyst. Generally, chromenopyrrole 31 (Y = NR) production was favored by using a more dense dispersion of P25. In contrast

Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides

• Armando Navarro-Vázquez

Beilstein J. Org. Chem. 2015, 11, 1441–1446, doi:10.3762/bjoc.11.156

• . From the ωB97 family we tested the ωB97 form, the ωB97X, which includes exact short-range HF exchange, and in addition the ωB97XD functional, which also includes Grimme’s dispersion correction [16]. The DFT tests employed a medium-size 6-31+G** basis in search of a methodology applicable to relatively

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• showcased the generation and use of organometallic species (i.e., Grignard reagents) in flow synthesis as well as in-line React-IR monitoring in order to precisely control the onset of late stage flow streams that are affected by dispersion effects thus marking the first use of this now commonly