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131.
Dr. Luca Gabrielli Dr. Laura Russo Dr. Ana Poveda Dr. Julian R. Jones Prof. Francesco Nicotra Dr. Jesús Jiménez‐Barbero Prof. Laura Cipolla 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(24):7856-7864
Hybrid organic–inorganic solids represent an important class of engineering materials, usually prepared by sol–gel processes by cross‐reaction between organic and inorganic precursors. The choice of the two components and control of the reaction conditions (especially pH value) allow the synthesis of hybrid materials with novel properties and functionalities. 3‐Glycidoxypropyltrimethoxysilane (GPTMS) is one of the most commonly used organic silanes for hybrid‐material fabrication. Herein, the reactivity of GPTMS in water at different pH values (pH 2–11) was deeply investigated for the first time by solution‐state multinuclear NMR spectroscopic and mass spectrometric analysis. The extent of the different and competing reactions that take place as a function of the pH value was elucidated. The NMR spectroscopic and mass spectrometric data clearly indicate that the pH value determines the kinetics of epoxide hydrolysis versus silicon condensation. Under slighly acidic conditions, the epoxy‐ring hydrolysis is kinetically more favourable than the formation of the silica network. In contrast, under basic conditions, silicon condensation is the main reaction that takes place. Full characterisation of the formed intermediates was carried out by using NMR spectroscopic and mass spectrometric analysis. These results indicate that strict control of the pH values allows tuning of the reactivity of the organic and inorganic moities, thus laying the foundations for the design and synthesis of sol–gel hybrid biomaterials with tuneable properties. 相似文献
132.
Dr. Stéphane Le Gac Dr. Btissam Najjari Dr. Vincent Dorcet Dr. Thierry Roisnel Dr. Luca Fusaro Prof. Dr. Michel Luhmer Dr. Eric Furet Dr. Jean‐François Halet Dr. Bernard Boitrel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):11021-11038
Overhanging carboxylic acid porphyrins have revealed promising ditopic ligands offering a new entry in the field of supramolecular coordination chemistry of porphyrinoids. Notably, the adjunction of a so‐called hanging‐atop (HAT) PbII cation to regular PbII porphyrin complexes allowed a stereoselective incorporation of the N‐core bound cation, and an allosterically controlled Newton’s cradle‐like motion of the two PbII ions also emerged from such bimetallic complexes. In this contribution, we have extended this work to other ligands and metal ions, aiming at understanding the parameters that control the HAT PbII coordination. The nature of the N‐core bound metal ion (ZnII, CdII), the influence of the deprotonation state of the overhanging COOH group and the presence of a neutral ligand on the opposite side (exogenous or intramolecular), have been examined through 1H NMR spectroscopic experiments with the help of radiocrystallographic structures and DFT calculations. Single and bis‐strap ligands have been considered. They all incorporate a COOH group hung over the N‐core on one side. For the bis‐strap ligands, either an ester or an amide group has been introduced on the other side. In the presence of a base, the mononuclear ZnII or CdII complexes incorporate the carbonyl of the overhanging carboxylate as apical ligand, decreasing its availability for the binding of a HAT PbII. An allosteric effector (e.g., 4‐dimethylaminopyridine (DMAP), in the case of a single‐strap ligand) or an intramolecular ligand (e.g., an amide group), strong enough to compete with the carbonyl of the hung COO?, is required to switch the N‐core bound cation to the opposite side with concomitant release of the COO?, thereby allowing HAT PbII complexation. In the absence of a base, ZnII or CdII binds preferentially the carbonyl of the intramolecular ester or amide groups in apical position rather than that of the COOH. This better preorganization, with the overhanging COOH fully available, is responsible for a stronger binding of the HAT PbII. Thus, either allosteric or acid–base control is achieved through stereoselective metalation of ZnII or CdII. In the latter case, according to the deprotonation state of the COOH group, the best electron‐donating ligand is located on one or the other side of the porphyrin (COO?>CONHR>COOR>COOH): the lower affinity of COOH for ZnII and CdII, the higher for a HAT PbII. These insights provide new opportunities for the elaboration of innovative bimetallic molecular switches. 相似文献
133.
Dr. Antonello Di Crescenzo Dr. Luca Bardini Dr. Bruna Sinjari Dr. Tonino Traini Dr. Lisa Marinelli Dr. Mauro Carraro Prof. Raimondo Germani Dr. Pietro Di Profio Prof. Sergio Caputi Prof. Antonio Di Stefano Prof. Marcella Bonchio Prof. Francesco Paolucci Prof. Antonella Fontana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16415-16423
Novel hydrogel phases based on positively charged and zwitterionic surfactants, namely, N‐[p‐(n‐dodecyloxybenzyl)]‐N,N,N‐trimethylammonium bromide (pDOTABr) and p‐dodecyloxybenzyldimethylamine oxide (pDOAO), which combine pristine carbon nanotubes (CNTs), were obtained, thus leading to stable dispersions and enhanced cross‐linked networks. The composite hydrogel featuring a well‐defined nanostructured morphology and an overall positively charged surface was shown to efficiently immobilise a polyanionic and redox‐active tetraruthenium‐substituted polyoxometalate (Ru4POM) by complementary charge interactions. The resulting hybrid gel has been characterised by electron microscopy techniques, whereas the electrostatic‐directed assembly has been monitored by means of fluorescence spectroscopy and ζ‐potential tests. This protocol offers a straightforward supramolecular strategy for the design of novel aqueous‐based electrocatalytic soft materials, thereby improving the processability of CNTs while tuning their interfacial decoration with multiple catalytic domains. Electrochemical evidence confirms that the activity of the catalyst is preserved within the gel media. 相似文献
134.
135.
We define a dispersionless tau-symmetric bihamiltonian integrable hierarchy on the space of pairs of functions analytic inside/outside the unit circle with simple poles at 0/∞ respectively, which extends the dispersionless 2D Toda hierarchy of Takasaki and Takebe. Then we construct the deformed flat connection of the infinite-dimensional Frobenius manifold M0 introduced by Carlet, Dubrovin and Mertens (2011) [3] and, by explicitly solving the deformed flatness equations, we prove that the extended 2D Toda hierarchy coincides with principal hierarchy of M0. 相似文献
136.
Sabina Strano-Rossi Luca Anzillotti Stefania Dragoni Roberto Maria Pellegrino Laura Goracci Vincenzo Lorenzo Pascali Gabriele Cruciani 《Analytical and bioanalytical chemistry》2014,406(15):3621-3636
This pilot study was performed to study the main metabolic reactions of four synthetic cannabinoids: JWH-015, JWH-098, JWH-251, and JWH-307 in order to setup a screening method for the detection of main metabolites in biological fluids. In silico prediction of main metabolic reactions was performed using MetaSite? software. To evaluate the agreement between software prediction and experimental reactions, we performed in vitro experiments on the same JWHs using rat liver slices. The obtained samples were analyzed by liquid chromatography-quadrupole time-of-flight and the identification of metabolites was executed using Mass-MetaSite? software that automatically assigned the metabolite structures to the peaks detected based on their accurate masses and fragmentation. A comparison between the experimental findings and the in silico metabolism prediction using MetaSite? software showed a good accordance between experimental and in silico data. Thus, the use of in silico metabolism prediction might represent a useful tool for the forensic and clinical toxicologist to identify possible main biomarkers for synthetic cannabinoids in biological fluids, especially urine, following their administration. Figure
JWH-098: Most probable predicted sites of metabolism and main metabolites formed in vitro 相似文献
137.
QuEChERS sample preparation for the determination of pesticides and other organic residues in environmental matrices: a critical review 总被引:4,自引:0,他引:4
Maria Concetta Bruzzoniti Leonardo Checchini Rosa Maria De Carlo Serena Orlandini Luca Rivoira Massimo Del Bubba 《Analytical and bioanalytical chemistry》2014,406(17):4089-4116
Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) is an extraction and clean-up technique originally developed for recovering pesticide residues from fruits and vegetables. Since its introduction, and until December 2013, about 700 papers have been published using the QuEChERS technique, according to a literature overview carried out using SciFinder, Elsevier SciVerse, and Google search engines. Most of these papers were dedicated to pesticide multiresidue analysis in food matrices, and this topic has been thoroughly reviewed over recent years. The QuEChERS approach is now rapidly developing beyond its original field of application to analytes other than pesticides, and matrices other than food, such as biological fluids and non-edible plants, including Chinese medicinal plants. Recently, the QuEChERS concept has spread to environmental applications by analyzing not only pesticides but also other compounds of environmental concern in soil, sediments, and water. To the best of our knowledge, QuEChERS environmental applications have not been reviewed so far; therefore, in this contribution, after a general discussion on the evolution and changes of the original QuEChERS method, a critical survey of the literature regarding environmental applications of conventional and modified QuEChERS methodology is provided. The overall recoveries obtained with QuEChERS and other extraction approaches (e.g., accelerated solvent extraction, ultrasonic solvent extraction, liquid/solid extraction, and soxhlet extraction) were compared, providing evidence for QuEChERS higher recoveries for various classes of compounds, such as biopesticides, chloroalkanes, phenols, and perfluoroalkyl substances. The role of physicochemical properties of soil (i.e., clay and organic carbon content, as well as cation exchange capacity) and target analytes (i.e., log KOW, water solubility, and vapor pressure) were also evaluated in order to interpret recovery and matrix effect data. 相似文献
138.
Elisa Michelini Luca Cevenini Maria Maddalena Calabretta Donato Calabria Aldo Roda 《Analytical and bioanalytical chemistry》2014,406(23):5531-5539
Bioluminescence-based analytical tools are suitable for high-throughput and high-content screening assays, finding widespread application in several fields related to the drug discovery process. Cell-based bioluminescence assays, because of their peculiar advantages of predictability, possibility of automation, multiplexing, and miniaturization, seem the most appealing tool for the high demands of the early stages of drug screening. Reporter gene technology and the bioluminescence resonance energy transfer principle are widely used, and receptor binding studies of new agonists/antagonists for a variety of human receptors expressed in different cell lines can be performed. Moreover, bioluminescence can be used for in vitro and in vivo real-time monitoring of pathophysiological processes within living cells and small animals. New luciferases and substrates have recently arrived on the market, further expanding the spectrum of applications. A new generation of probes are also emerging that promise to revolutionize the preclinical imaging market. This formidable toolbox is demonstrated to facilitate the implementation of the three Rs principle in the early drug discovery process, in compliance with ethical and responsible research to reduce cost and improve the reliability and predictability of results. 相似文献
139.
Sampling series play a crucial role in Signal and Image Processing. In this note, we illustrate a general method to construct Sampling series and to determine their convergence in Orlicz spaces. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
140.
Prof. Gianlorenzo Bussetti Claudia Filoni Prof. Andrea Li Bassi Dr. Alberto Bossi Prof. Marcello Campione Prof. Alessio Orbelli Biroli Prof. Chiara Castiglioni Dr. Silvia Trabattoni Dr. Stefania De Rosa Prof. Luca Tortora Prof. Franco Ciccacci Prof. Lamberto Duò 《ChemistryOpen》2021,10(8):748-755
We have recently discussed how organic nanocrystal dissolution appears in different morphologies and the role of the solution pH in the crystal detriment process. We also highlighted the role of the local molecular chemistry in porphyrin nanocrystals having comparable structures: in water-based acid solutions, protonation of free-base porphyrin molecules is the driving force for crystal dissolution, whereas metal (ZnII) porphyrin nanocrystals remain unperturbed. However, all porphyrin types, having an electron rich π-structure, can be electrochemically oxidized. In this scenario, a key question is: does electrochemistry represent a viable strategy to drive the dissolution of both free-base and metal porphyrin nanocrystals? In this work, by exploiting electrochemical atomic force microscopy (EC-AFM), we monitor in situ and in real time the dissolution of both free-base and metal porphyrin nanocrystals, as soon as molecules reach the oxidation potential, showing different regimes according to the applied EC potential. 相似文献