Highly stable and reusable immobilized formate dehydrogenases: Promising biocatalysts for in situ regeneration of NADH

• Barış Binay,
• Dilek Alagöz,
• Deniz Yildirim,
• Ayhan Çelik and
• S. Seyhan Tükel

Beilstein J. Org. Chem. 2016, 12, 271–277, doi:10.3762/bjoc.12.29

• methanol or formate from CO2 [10][11]. It was reported that FDH is a promising enzyme for the regeneration of NADH since the reaction product of FDH-catalyzed formate oxidation is CO2 which does not interfere with the purification of the final product [12][13]. However, free FDHs have low thermal stability

• boidinii as cross-linked enzyme aggregate (CLEA) and demonstrated that the residual activity and thermal stability of CLEA were strictly dependent on the type of cross-linker. Epoxy group containing supports are widely used in enzyme immobilization studies to obtain highly stable enzyme preparations by

• ethylenediamine and then activated with glutaraldehyde, and Immobead 150 support functionalized with aldehyde groups. The optimum conditions of free and immobilized FDH preparations were determined for formate oxidation. The thermal stability of free and immobilized FDH preparations was tested at 35 and 50 °C

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• energy barrier for complex dissociation revealed the thermal stability conferred upon guest encapsulation within the CD molecules. NMR experiments allow the enantiomers discrimination in presence of a chiral additive to create visible diastereomeric species. 31P NMR spectroscopy in presence of CDs as

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• [13][14]. One of the main disadvantages of PUFAs is their low oxidative and thermal stability. The rate of oxidation of such FAs (especially at higher temperatures) drastically increases with the increasing number of double bonds present, even by few thousand times. For example, the relative oxidation

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

• evaluated and compared to those of the non-rotaxane counterpart 3. The influence of TM-βCD or TM-γCD encapsulation on the thermal stability, solubility in common organic solvents, film forming ability was also investigated. Polyrotaxane 3·TM-βCD exhibits a hypsochromic shift, while 3·TM-γCD displays a

• 3·TM-βCD polyrotaxane. The thermal stability of the copolymers was also investigated by TGA (not shown) and the TGA data revealed that all polymers were stable up to about 300 °C. The absorption spectra of 3·TM-βCD and 3·TM-γCD polyrotaxanes and the unthreaded 3 counterpart at a concentration of 10

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• reaction temperature from 160 °C to 200 °C accelerated the decarboxylation of CF3CO2K [36] (Scheme 3). The trifluoromethylation using a microreactor resulted in a good yield within a short reaction time by virtue of the thermal stability of CF3Cu and control of mixing. Taking advantage of the flow

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• attention has been paid to organic aromatic or heterocyclic hydroperoxides, probably due to their low thermal stability and high reactivity. Stable organic hydroperoxides were isolated in the early 1950s as products of autoxidation as well as catalytic oxygenation of indoles and tetrahydrocarbazoles [3][4

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• has exhibited a rapid growth in use in recent years and is quickly becoming a mainstream catalyst in metathesis-type reactions (Figure 11). These complexes have received significant attention due to their high activity in olefin metathesis [72][73][74][75][76][77][78], their thermal stability and

• increased activity and maintained the same thermal stability. Again, these complexes showed similar activity to the Grubbs 2nd generation catalysts [77][78], and are stable when stored under air. Nolan reported the synthesis of Grubbs’ 2nd generation catalyst (15) from indenylidene complexes 84, by simple

• 2009, surely inspired by the aforementioned work, the Verpoort group reported a family of indenylidene Schiff base–ruthenium complexes (111a–f, Figure 17) for CM and RCM reactions in air [98]. They combined the higher thermal stability of indenylidene complexes and the tunability and stability of

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• determined solid contents often times exceeded the theoretical value derived from the amounts of monomer and surfactant added. This indicates that the catalysts have sufficient activity and thermal stability under the chosen conditions to promote complete ROMP of DCPD and the DCPD/COE monomer mixture. After

• –alkylidene complexes 14 and 15, they should exhibit much lower thermal stability due to high initiation rates [57]. However, the ability to quantitatively convert the monomers indicates that species 14 and 15 either are stabilized in the aqueous solvent, i.e., via H2O donation, or the species rapidly migrate

Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions

• Andrzej Tracz,
• Mateusz Matczak,
• Katarzyna Urbaniak and
• Krzysztof Skowerski

Beilstein J. Org. Chem. 2015, 11, 1823–1832, doi:10.3762/bjoc.11.198

• anionic ligands were also reported very recently [22]. The former catalyst exhibited thermal stability and efficiency comparable with the original complex having two chlorides, while the difluoride catalyst showed low catalytic activity. Finally, alternative anionic ligands have been used in order to

Ruthenium indenylidene “1^st generation” olefin metathesis catalysts containing triisopropyl phosphite

• Stefano Guidone,
• Fady Nahra,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2015, 11, 1520–1527, doi:10.3762/bjoc.11.166

• ” cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L

• synergistic effects in the case of the mixed phosphine/phosphite system. Complex 1 is a thermally-switchable, latent pre-catalyst displaying higher thermal stability compared to the phosphine-based Ind-I. Consequently, a brief study of the scope of the reaction was investigated employing “1st generation

• reaction showing similarities with cis-Caz-1 in terms of reactivity. Both pre-catalysts need thermal activation; they display an induction period in the reaction profiling and exhibit higher thermal stability compared to their phosphine-based analogues. In terms of catalytic efficiency, Ind-I was found

Thermal properties of ruthenium alkylidene-polymerized dicyclopentadiene

• Yuval Vidavsky,
• Yotam Navon,
• Yakov Ginzburg,
• Moshe Gottlieb and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2015, 11, 1469–1474, doi:10.3762/bjoc.11.159

• initiators where only cross-linked polymers are obtained. This polyolefinic cross-linked thermoset material exhibits outstanding thermal stability [22], mechanical strength [23], fracture toughness [24] and dielectric characteristics [25]. Thanks to these properties PDCPD has become a very attractive polymer

Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity

• Karolina Żukowska,
• Eva Pump,
• Aleksandra E. Pazio,
• Krzysztof Woźniak,
• Luigi Cavallo and
• Christian Slugovc

Beilstein J. Org. Chem. 2015, 11, 1458–1468, doi:10.3762/bjoc.11.158

• -position changes the thermodynamic equilibrium favoring the trans- over the cis-isomers. In any case, a remarkable thermal stability of all studied compounds was found. Intrigued by the observed phenomenon, we turned to structural studies. Structures of 14 and 15 have been determined using single-crystal X

• thermal stability of the precatalyst becomes irrelevant once it is in the presence of the substrate [33], because it is the thermal stability of the actual active species in the reaction mixture that governs the reaction outcome. In the present case, the methylidene complex formed during metathesis with

• educt as well as that of the product is observed. However, the results for 5a as the precatalyst make clear that the thermal stability of the methylidene is not the only factor governing the outcome of the studied reactions. If the stability of the methylidene were the only crucial factor in all cases

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• porphyrins can be modulated by introducing diverse functionalities on their periphery or changing the metal ions in the porphyrin core [3][4]. Due to the high thermal stability and extended π-electron system, porphyrins are very useful for the construction of molecular switches [5][6] and other organic

Carboxylated dithiafulvenes and tetrathiafulvalene vinylogues: synthesis, electronic properties, and complexation with zinc ions

• Yunfei Wang and
• Yuming Zhao

Beilstein J. Org. Chem. 2015, 11, 957–965, doi:10.3762/bjoc.11.107

• of 9). It is therefore reasonable to propose that the microporosity in 8 is directly related to the coordination polymer structure. Finally, the thermal stability of coordination polymer 8 and Zn-DTF 9 were evaluated by differential scanning calorimetric (DSC) analysis, and detailed DSC traces are

• illustrated in Figure 6. The DSC data of Zn-TTFV 8 (Figure 6A) manifested very good thermal stability up to 400 °C, without any significant melting or decomposition except a slight phase transition at 272 °C. Comparatively, the DSC trace of carboxyl-TTFV ligand 6 showed a distinctive melting process at 317 °C

• considerably improved thermal stability, a property particularly beneficial for practical device and material applications. Conclusion In summary, we have synthesized carboxylated diphenyl-TTFV 6 and phenyl-DTF 7 as redox-active ligands to complex with Zn(II) ions. The electronic and electrochemical properties

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• 10.3762/bjoc.11.91 Abstract Multivalent biomolecular interactions allow for a balanced interplay of mechanical stability and malleability, and nature makes widely use of it. For instance, systems of similar thermal stability may have very different rupture forces. Thus it is of paramount interest to study

• latent catalysts for self-healing, mechanochroism or mechanoluminescence [14]. The thermal stability of a molecular system is inversely proportional to the thermal off-rate. However, this alone gives an incomplete image of bond rupture under physiological conditions. For example, depending on the

• ) model, finally giving the rupture length rb and the thermal off-rate koff (a measure of the inverse thermal stability) [20][21][22]. This method is especially useful in the case of interactions with low affinity of low yield that are inaccessible for ensemble measurements. For example in 2009

DNA display of glycoconjugates to emulate oligomeric interactions of glycans

• Alexandre Novoa and
• Nicolas Winssinger

Beilstein J. Org. Chem. 2015, 11, 707–719, doi:10.3762/bjoc.11.81

• helical structure and thermal stability. Surface plasmon resonance (SPR) affinity measurements with murine C-type lectin receptor (mMGL) showed specific binding only for duplexes containing two or four Lewis-X units. Alternatively, Ebara and co-workers have shown that glycan–DNA conjugates can be accessed

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• across the single С–N bond (the С2–N1–С3–C4 dihedral angle is 4.3°, Figure 1), unlike its C4-aryl-substituted analogs with the angle of 73–75° [26]. The Е-configuration of the С=N bond, unfavorable for cyclization into 1,4-oxazine, explains the enhanced thermal stability of compound 3e. Heating azadiene

Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

• Martin Popr,
• Sergey K. Filippov,
• Nikolai Matushkin,
• Juraj Dian and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20

• , Czech Republic Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16, Prague 2, Czech Republic 10.3762/bjoc.11.20 Abstract The thermal stability of the monosubstituted cationic cyclodextrin (CD) derivatives PEMEDA-β-CD and

• , yet robust and a straightforward process as well. Keywords: cyclodextrins; inclusion properties; solid surface; tetraalkylammonium derivatives; thermal stability; Introduction Cyclodextrins (CDs) are a very interesting group of natural macrocyclic carbohydrates, which were first described by

• transport of aromatic compounds [30]. In this paper we report on a comprehensive study of the properties of the novel monosubstituted cationic CD derivative PEMPDA-β-CD (PErMethylated PropyleneDiAmine substituted). Its thermal stability is compared to the previously reported analogue PEMEDA-β-CD

Enhancing the reactivity of 1,2-diphospholes in cycloaddition reactions

• Almaz Zagidullin,
• Vasili Miluykov,
• Elena Oshchepkova,
• Artem Tufatullin,
• Olga Kataeva and
• Oleg Sinyashin

Beilstein J. Org. Chem. 2015, 11, 169–173, doi:10.3762/bjoc.11.17

• (with thermal stability up to 190 °C) and 2H-phospholes (exhibiting high reactivity in the cycloaddition reaction at 25 °C) [9][10][11]. In the present work, attempts to increase the reactivity of the dienic system of 1,2-diphospholes using two different approaches are described: (a) by the introduction

• reaction mixtures showed many multiplets at 80 and −40 ppm with a coupling constant 1JPP ca. 200–210 Hz characteristic for the products of [4 + 2] cycloaddition reaction – 1,7-diphosphanorbornadienes [9][11]. Remarkably, 1-alkyl-1,2-diphospholes without EWGs reveal significant thermal stability and

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• solvent could significantly influence the activity and selectivity of the enzymatic reaction as well as increase the thermal stability of enzymes [66]. The high sensitivity of lipases towards the medium environment mainly stems from experimental observations that different organic solvents had a different

A comparative study of the interactions of cationic hetarenes with quadruplex-DNA forming oligonucleotide sequences of the insulin-linked polymorphic region (ILPR)

• Darinka Dzubiel,
• Heiko Ihmels,
• Mohamed M. A. Mahmoud and
• Laura Thomas

Beilstein J. Org. Chem. 2014, 10, 2963–2974, doi:10.3762/bjoc.10.314

• thermal stability of the ILPR-DNA with respect to unfolding was also examined by emission spectroscopy in K+- and Na+-containing buffer, i.e., the melting temperature, Tm, of the dye-labelled quadruplex-forming ILPR sequence Fa2T [fluorescein-d(ACAG4TGTG4ACAG4TGTG4)-tetramethylrhodamine] was determined by

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• oligofluorene arm length and substitution patterns of the central BODIPY core have been synthesised, leading to two families of compounds, T-B1–T-B4 and Y-B1–Y-B4, with T- and Y-shaped motifs, respectively. Thermal stability, cyclic voltammetry, absorption and photoluminescence spectroscopy of each member of

• molecular bromine which was used previously [33]. Thermal, electrochemical and optical properties TGA and DSC analyses All of the final target compounds showed good thermal stability. Thermogravimetric analysis (TGA) revealed decomposition temperatures in the range 396–442 °C (Table 1, Figure S1, Supporting

Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

• Véronique Nardello-Rataj and
• Loïc Leclercq

Beilstein J. Org. Chem. 2014, 10, 2603–2622, doi:10.3762/bjoc.10.273

• -CD inclusion complexes greatly improves the thermal stability of the biocide with no negative influence on its activity and toxicity. In 2013, Hill et al. reported that β-CD can be used to encapsulate various essential oil constituents (e.g., trans-cinnamaldehyde, eugenol, etc.) for antimicrobial

• their high thermal stability, low toxicity to human cells and effective broad-spectrum antibacterial activity. The antibacterial activity of these nanoparticles is probably due to their rapid breakdown which releases ionic silver that interact with the thiol residues of bacterial enzymes [80]. As a

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• 30000. Thermogravimetric analyses (Figure 3) clearly show that thermal stability increases by selecting molecular weights greater than 10000 Da (red line) and 30000 Da (green line), and these samples are characterized by a remarkable thermal stability. Degradation of such larger fractions starts at

Reversibly locked thionucleobase pairs in DNA to study base flipping enzymes

• Christine Beuck and
• Elmar Weinhold

Beilstein J. Org. Chem. 2014, 10, 2293–2306, doi:10.3762/bjoc.10.239

• absorption band above 300 nm in the UV spectrum (c, solid) compared to the spectrum of 1I6S∙2U4S (dashed). The thermal stability of the cross-linked duplex 1I6S-Et-S4U2 (d, solid) is drastically increased compared to 1I6S∙2U4S (dashed). Characterization of HPLC-purified cross-linked duplex 1G6S-Et-S4U2 (a

• ) by denaturing anion exchange HPLC (b). Alkylation at the sulfur atoms within the thionucleobases is confirmed by the strong reduction of the absorption band above 300 nm in the UV spectrum of 1G6S-Et-S4U2 (c, solid) compared to the spectrum of 1G6S∙2U4S (dashed). The thermal stability of the cross