W Tungsten

A rapid and efficient process for the measurement of lignin content in the plant cell walls is reported. The described method can be used to analyze ball- or Wiley-milled samples at a microscale via direct dissolution and 1H NMR analysis of biomass using perdeuterated pyridinium chloride/[D6]DMSO bisolvent system.

Ionic liquids (ILs) can be partially substituted by glycerol or glycerol carbonate as cheap, safe, and renewably sourced co-solvents in the acid-catalyzed dehydration of fructose and inulin to 5-hydroxymethylfurfural (HMF). In the particular case of glycerol, we found that HMF can be conveniently extracted from the IL/glycerol (65:35) mixture with methylisobutylketone, limiting the reactivity of glycerol with HMF and allowing the recovery of HMF with a high purity (95 %). Influences of the fructose content, temperature, and the nature of the ionic liquid are also discussed. The possible use of industrial-grade glycerin is also investigated. We demonstrate that by using glycerol carbonate, up to 90 wt % of the IL can be successfully substituted, decreasing the environmental costs of traditional IL-based processes.Super subs: The amount of the ionic liquid [BMIM]Cl required for the acid-catalyzed dehydration of fructose and inulin into HMF, over Amberlyst 70 resin as solid acid catalyst, can be reduced by substituting it (up to 90 wt %) with large amounts of glycerol or glycerol carbonate; cheap co-solvents from renewable sources.

Rapid and sensitive methods to detect proteins and protein denaturation have become increasingly needful in the field of proteomics, medical diagnostics, and biology. In this paper, we have reported the synthesis of a new cationic water-soluble conjugated polymer that contains fluorene and diene moieties in the backbone (PFDE) for protein identification by sensing an array of PFDE solutions in different ionic strengths using the linear discriminant analysis technique (LDA). The PFDE can form complexes with proteins by electrostatic and/or hydrophobic interactions and exhibits different fluorescence response. Three main factors contribute to the fluorescence response of PFDE, namely, the net charge density on the protein surface, the hydrophobic nature of the protein, and the metalloprotein characteristics. The denaturation of proteins can also be detected using PFDE as a fluorescent probe. The interactions between PFDE and proteins were also studied by dynamic light scattering (DLS) and isothermal titration microcalorimetry (ITC) techniques. In contrast to other methods based on conjugated polymers, the synthesis of a series of quencher or dye-labeled acceptors or protein substrates has been avoided in our method, which significantly reduces the cost and the synthetic complexity. Our method provides promising applications on protein identification and denaturation detection in a simple, fast, and label-free manner based on non-specific interaction-induced perturbation of PFDE fluorescence response.Detection made easy: A new cationic water-soluble conjugated polymer containing fluorene and diene moieties in the backbone has been synthesized. It provides promising applications on protein identification and denaturation detection in a simple, fast and label-free manner based on non-specific interaction-induced perturbation of the polymer fluorescence response with linear discriminant analysis analysis.

Micro- and macroscopic studies of nucleation and growth processes of MnAlPO-5 nanosized crystals under ionothermal synthesis conditions are reported herein. The samples treated at 150 °C were extracted from the reaction mixture at various stages of crystallization, and characterized by XRD; SEM; thermogravimetric analysis (TGA); 31P and 27Al solid-state magic angle spinning (MAS) NMR, Raman, UV/Vis, and X-ray fluorescence spectroscopy (XRF). The starting raw materials (alumina, manganese, and phosphorous) were dissolved completely in the ionic liquid and transformed into an amorphous solid after 5 h of ionothermal treatment. This amorphous solid then undergoes structural changes over the following 5–25 h, which result in an intermediate phase that consists of octahedral Al species linked to the manganese and phosphate species. The first MnAlPO-5 nuclei on the surface of the intermediate can be observed after 50 h ionoheating. These nuclei further grow, as the surface of the intermediate is in full contact with the ionic liquid, to give crystalline MnAlPO-5 nanoparticles with a mean diameter of 80 nm. The crystals become fully detached from the intermediate and are then liberated as discrete particles after 90 h heating. The transformation process from amorphous to intermediate and then to the crystalline MnAlPO-5 nanoparticles shows that nucleation starts at the solid–liquid interface and continues through surface-to-core reversed-growth until the entire amorphous solid is transformed into discrete nanocrystals.Growth control: Nucleation and growth processes of MnAlPO-5 nanosized crystals under ionothermal synthesis conditions are reported herein. Samples were examined at various stages of crystal growth of nanosized MnAlPO-5 under ionothermal conditions (see figure).

In the 129Xe NMR-based biosensing approach in which the hyperpolarized noble gas is transported to biological receptors for a sensitive molecular imaging, cryptophanes are excellent xenon host systems. However to avoid formation of self-organized systems, these hydrophobic cage molecules can be rendered water soluble by introduction of ionic groups. We show that the sensitivity of xenon to its local environment and the presence of these ionic functions can lead to interesting properties. For a first water-soluble cryptophane derivative, we show that a precise monitoring of the local pH can be performed. For a second cryptophane, the presence of ionic groups close to the cryptophane cavity modifies the xenon binding constant and in–out exchange rate. The latter allows the tuning of physical properties of xenon–cryptophane interactions without resorting to a change of the cavity size. These results open new perspectives on the influence of chemical modifications of cryptophanes for optimizing the biosensor properties.(Xe)eing is believing! The interaction of hyperpolarized xenon with two water-soluble cryptophanes reveals interesting sensing properties. The presence of ionic substituents on the aromatic rings of the cage molecules renders the chemical shift of encapsulated xenon dependent on pH (see figure). When the ionic groups are, however, closer to the cavity portals, the nature of the counterion influences both the thermodynamics and the kinetics of the xenon binding.

Metal-mediated base pair formation, resulting from the interaction between metal ions and artificial bases in oligonucleotides, has been developed for its potential application in nanotechnology. We have recently found that the T:T mismatched base pair binds with HgII ions to generate a novel metal-mediated base pair in duplex DNA. The thermal stability of the duplex with the T-Hg-T base pair was comparable to that of the corresponding T:A or A:T. The novel T-Hg-T base pair involving the natural base thymine is more convenient than the metal-mediated base pairs involving artificial bases due to the lack of time-consuming synthesis. Here, we examine the specificity and thermodynamic properties of the binding between HgII ions and the T:T mismatched base pair. Only the melting temperature of the duplex with T:T and not of the perfectly matched or other mismatched base pairs was found to specifically increase in the presence of HgII ions. HgII specifically bound with the T:T mismatched base pair at a molar ratio of 1:1 with a binding constant of 106 M−1, which is significantly higher than that for nonspecific metal ion–DNA interactions. Furthermore, the higher-order structure of the duplex was not significantly distorted by the HgII ion binding. Our results support the idea that the T-Hg-T base pair could eventually lead to progress in potential applications of metal-mediated base pairs in nanotechnology.Mercury rising: We have investigated the binding mode between HgII ions and the T:T mismatched base pair. HgII ions surrounded by structured water molecules can be dehydrated, and the two protons at the N3 positions of T:T can then be released, as shown in the scheme. Dehydrated HgII ions can then bind with the deprotonated thymine bases to form N3-Hg-N3.

The 1,2,4-trimethyltriazolylidene (ditz) ligand allows the preparation of homo- and heterodimetallic complexes of Pt2 and Ir–Pt. These two complexes have been characterized by means of spectroscopic and diffractommetric techniques. The catalytic activity of these complexes, together with that of other Pt-based compounds, has been explored in the cyclization–addition of alkynyl alcohols and indoles. The Ir–Pt complex [{PtI2(py)}(μ-ditz){IrI2(Cp*)}] (py=pyridine; Cp*=pentamethylcyclopentadienyl) allows the combination of an iridium-mediated oxidative cyclization of 2-(ortho-aminophenyl)ethanol to form indoles, with a further step employing a Pt-based multistep reaction that functionalizes indoles. Our results show that the Ir–Pt complex is a very active catalyst in this new multistep preparation of functionalized indoles from the reaction of an amino alcohol with alkynyl alcohols.Three in one: A heterodimetallic complex of Ir–Pt (see graphic) with a triazolyldiylidene linker has been obtained and fully characterized. The complex brings together some of the catalytic properties typically shown by Ir and Pt catalysts. A multistep reaction employing the Ir-mediated oxidative cyclization of 2-(ortho-aminophenyl)ethanol and the Pt-catalyzed cyclization–addition of alkynyl alcohols to indoles is reported.

A large series of ionic liquids (ILs) based on the weakly coordinating alkoxyaluminate [Al(hfip)4]− (hfip: hexafluoroisopropoxy) with classical as well as functionalized cations were prepared, and their principal physical properties determined. Melting points are between 0 ([C4MMIM][Al(hfip)4]) and 69 °C ([C3MPip][Al(hfip)4]); three qualify as room-temperature ILs (RTILs). Crystal structures for six ILs were determined; their structural parameters and anion–cation contacts are compared here with known ILs, with a special focus on their influence on physical properties. Moreover, the biodegradability of the compounds was investigated by using the closed-bottle and the manometric respirometry test. Temperature-dependent viscosities and conductivities were measured between 0 and 80 °C, and described by either the Vogel–Fulcher–Tammann (VFT) or the Arrhenius equations. Moreover, conductivities and viscosities were investigated in the context of the molecular volume, Vm. Physical property–Vm correlations were carried out for various temperatures, and the temperature dependence of the molecular volume was analyzed by using crystal structure data and DFT calculations. The IL ionicity was investigated by Walden plots; according to this analysis, [Al(hfip)4]− ILs may be classified as “very good to good ILs”; while [C2MIM][Al(hfip)4] is a better IL than [C2MIM][NTf2]. The dielectric constants of ten [Al(hfip)4]− ILs were determined, and are unexpectedly high (εr=11.5 to 16.8). This could be rationalized by considering additional calculated dipole moments of the structures frozen in the solid state by DFT. The determination of hydrogen gas solubility in [Al(hfip)4]− RTILs by high-pressure NMR spectroscopy revealed very high hydrogen solubilities at 25 °C and 1 atm. These results indicate the significant potential of this class of ILs in manifold applications.New RTILs: A series of ionic liquids (ILs) based on the weakly coordinating anion [Al(hfip)4]− (see figure) has been synthesized and thoroughly characterized. The ILs were found to have widely interesting properties that suggest potential for these ILs in many applications.

A series of six double-functionalised nucleosides, in which aromatic moieties were inserted into the 5′-(S)-C-position, were synthesised and incorporated into DNA duplexes. The aromatic moieties were thymine-1-yl, phenyl, 1,2,3-triazol-1-yl, 1,2,3-triazol-4-yl, 4-(uracil-5-yl)-1,2,3-triazol-1-yl and 4-phenyl-1,2,3-triazol-1-yl. The DNA duplexes were studied with UV melting curves, CD spectroscopy and molecular modelling. The results showed that the aromatic moieties in some cases interact in the minor groove forming DNA zipper structures. The strongest specific interaction was found between two thymines or between a thymine and a phenyl group in a crossed (−3)-zipper motif (i.e., with two base pairs interspacing the modifications). Modelling revealed that the interaction is aromatic stacking across the minor groove. Also, the extended uracil-triazole moiety demonstrated zipper contacts in the minor groove as well as binding to the floor of the groove.Communication in the minor groove: A series of aromatic moieties were inserted in the minor groove of DNA through 5′-(S)-C-substituted nucleosides. A strong and specific interaction was found between a thymine and a phenyl group in a crossed (−3)-zipper motif. Modelling revealed that the interaction is due to aromatic stacking across the minor groove (see figure).

A detailed study of the synthesis and photophysical properties of a new series of dipolar organic photosensitizers that feature a 1,3-cyclohexadiene moiety integrated into the π-conjugated structural backbone has been carried out. Dye-sensitized solar cells (DSSCs) based on these structurally simple dyes have shown appreciable photo-to-electrical energy conversion efficiency, with the highest one up to 4.03 %. Solvent-dependent fluorescence studies along with the observation of dual emission on dye 4 b and single emission on dyes 4 a and 32 suggest that dye 4 b possesses a highly polar emissive excited state located at a lower-energy position than at the normal emissive excited state. A detailed photophysical investigation in conjunction with computational studies confirmed the twisted intramolecular charge-transfer (TICT) state to be the lowest emissive excited state for dye 4 b in polar solvents. The relaxation from higher-charge-injection excited states to the lowest TICT state renders the back-electron transfer process a forbidden one and significantly retards the charge recombination to boost the photocurrent. The electrochemical impedance under illumination and transient photovoltage decay studies showed smaller charge resistance and longer electron lifetime in 4 b-based DSSC compared to the DSSCs with reference dyes 4 a and 32, which further illustrates the positive influence of the TICT state on the performance of DSSCs.To dye for: A series of organic dyes that feature a 1,3-cyclohexadiene conjugated moiety integrated into the π-conjugated framework has been synthesized and studied. Dye-sensitized solar cells based on these have shown appreciable conversion efficiency. Studies suggest the accessibility of the twisted internal charge-transfer state (TICT) in polar solvents (see figure).