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41.
Umar Farid Maria Luisa Aiello Prof. Stephen J. Connon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10074-10079
A new catalytic methodology was developed to promote an efficient one-pot kinetic resolution of racemic aldehydes with selectivity (s*) of up to 91 (99:1 d.r., >99 % ee) in a cycloaddition reaction with enolizable anhydrides to afford dihydroisocoumarin products (a core prevalent in natural products and molecules of medicinal interest) containing three contiguous stereocentres. 相似文献
42.
Emilie Boulard Vivien Zibulski Luisa Oertel Dr. Philip Lienau Dr. Martina Schäfer Dr. Ursula Ganzer Dr. Ulrich Lücking 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4378-4388
A short synthetic approach with broad scope to access five- to seven-membered cyclic sulfoximines in only two to three steps from readily available thiophenols is reported. Thus, simple building blocks were converted to complex molecular structures by a sequence of S-alkylation and one-pot sulfoximine formation, followed by intramolecular cyclization. Seventeen structurally diverse cyclic sulfoximines were prepared in high overall yields. In vitro evaluation of these underrepresented, three-dimensional, cyclic sulfoximines with respect to properties relevant to medicinal chemistry did not reveal any intrinsic flaw for application in drug discovery. 相似文献
43.
44.
Emanuela Fabiola Craparo Girolamo Teresi Maria Chiara Ognibene Maria Pia Casaletto Maria Luisa Bondì Gennara Cavallaro 《Journal of nanoparticle research》2010,12(7):2629-2644
In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without
using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG2000) were functionalized with poly(lactic acid) (PLA) through 1,1′-carbonyldiimidazole (CDI) activation to obtain PHEA–PLA and
PHEA-PEG2000–PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that derivatization reactions occurred. Nanoparticles
were obtained from PHEA–PLA and PHEA-PEG2000–PLA graft copolymers by using the high pressure homogenization-solvent evaporation method, avoiding the use of surfactants
or stabilizing agents. Polymeric nanoparticles were characterized by dimensional analysis, before and after freeze-drying
process, and Scanning Electron Microscopy (SEM). Zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) analysis
demonstrated the presence of PEG and/or PHEA onto the PHEA-PEG2000–PLA and PHEA–PLA nanoparticle surface, respectively. 相似文献
45.
Ioana Konz Beatriz Fernández M. Luisa Fernández Rosario Pereiro Héctor González Lydia Álvarez Miguel Coca-Prados Alfredo Sanz-Medel 《Analytical and bioanalytical chemistry》2013,405(10):3091-3096
Laser ablation coupled to inductively coupled plasma mass spectrometry has been developed for the elemental imaging of Mg, Fe and Cu distribution in histological tissue sections of fixed eyes, embedded in paraffin, from human donors (cadavers). This work presents the development of a novel internal standard correction methodology based on the deposition of a homogeneous thin gold film on the tissue surface and the use of the 197Au+ signal as internal standard. Sample preparation (tissue section thickness) and laser conditions were carefully optimized, and internal normalisation using 197Au+ was compared with 13C+ correction for imaging applications. 24Mg+, 56Fe+ and 63Cu+ distributions were investigated in histological sections of the anterior segment of the eye (including the iris, ciliary body, cornea and trabecular meshwork) and were shown to be heterogeneously distributed along those tissue structures. Reproducibility was assessed by imaging different human eye sections from the same donor and from ten different eyes from adult normal donors, which showed that similar spatial maps were obtained and therefore demonstrate the analytical potential of using 197Au+ as internal standard. The proposed analytical approach could offer a robust tool with great practical interest for clinical studies, e.g. to investigate trace element distribution of metals and their alterations in ocular diseases. Figure
Development of a new internal standard correction methodology for qualitative elemental imaging by LA-ICP-MS 相似文献
46.
Francisco Ardini Francesco Soggia Maria Luisa Abelmoschi Emanuele Magi Marco Grotti 《Analytical and bioanalytical chemistry》2013,405(2-3):665-677
To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP–AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP–MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots. Figure
Roots, stems and leaves of different Nicotiana langsdorffii genotypes exposed to abiotic stresses were analysed by ICP-AES and ICP-MS, obtaining information on the distribution of 29 major and trace elements in the samples 相似文献
47.
Ernesto Mesto Fernando Scordari Maria Lacalamita Luisa De Cola Roberta Ragni Gianluca Maria Farinola 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(5):480-482
The title complex, [Ir2(C18H13FNO2S)4Cl2]·C7H8, was crystallized from dichloromethane solution under a toluene atmosphere. It is a dimeric complex in which each of the two IrIII centres is octahedrally coordinated by two bridging chloride ligands and by two chelating cyclometalated 2‐(4‐benzylsulfonyl‐2‐fluorophenyl)pyridine ligands. The crystal structure analysis unequivocally establishes the trans disposition of the two cyclometalated ligands bound to each IrIII centre, contrary to our previous hypothesis of a cis disposition. The latter was based on the 1H NMR spectra of a series of dimeric benzylsulfonyl‐functionalized dichloride‐bridged iridium complexes, including the compound described in the present work [Ragni et al. (2009). Chem. Eur. J. 15 , 136–148]. The toluene solvent molecules, embedded in cavities in the crystal structure, are highly disordered and could not be modelled successfully; their contribution was removed from the refinement using the SQUEEZE routine in the program PLATON [Spek (2009). Acta Cryst. D 65 , 148–155]. 相似文献
48.
Luisa Maurelli Elena Ionata Francesco La Cara Alessandra Morana 《Applied biochemistry and biotechnology》2013,170(5):1104-1118
Chestnut shell (CS) is an agronomic residue mainly used for extraction of antioxidants or as adsorbent of metal ions. It also contains some polysaccharide that has not been considered as potential source of fermentable sugars for biofuel production until now. In this study, the effect of different pretreatment methods on CS was evaluated in order to obtain the greatest conversion of cellulose and xylan into fermentable sugars. Hot acid impregnation, steam explosion (acid-catalysed or not), and aqueous ammonia soaking (AAS) were selected as pretreatments. The pretreated biomass was subjected to saccharification with two enzyme cocktails prepared from commercial preparations, and evaluation of the best pretreatment and enzyme cocktail was based on the yield of fermentable sugars produced. As AAS provided the best result after preliminary experiments, enhancement of sugar production was attempted by changing the concentrations of ammonium hydroxide, enzymes, and CS. The optimal pretreatment condition was 10 % ammonium hydroxide, 70 °C, 22 h with CS at 5 % solid loading. After saccharification of the pretreated CS for 72 h at 50 °C and pH 5.0 with a cocktail containing cellulase (Accellerase 1500), beta-glucosidase (Accellerase BG), and xylanase (Accellerase XY), glucose and xylose yields were 67.8 and 92.7 %, respectively. 相似文献
49.
Francesco Soggia Maria Luisa Abelmoschi Simona Dalla Riva Rodolfo De Pellegrini Roberto Frache 《International journal of environmental analytical chemistry》2013,93(4):367-378
Abstract The Project on an Antarctic Environmental Specimen Bank (Banca Campioni Ambientali Antartici—BCAA) began in 1994 in order to collect and classify samples from the Antarctic ecosystem to be used for future studies. The objectives of the project are similar to the general aims of the Environmental Specimen Banks, but they specifically focus on the chemical aspects concerning the research activities of the Italian Project on the “Micropollutants Chemistry” (Sector “Chemical Contamination” of the Italian Antarctic Research Programme—PNRA). During these first years the facilities suitable for storing a significant number of specimens (now over 2,000) at different temperatures (from ?30°C to ?150°C) and a database system, specifically designed for managing and consulting information concerning both the storage of samples and data on their chemical characterisation, have been developed. In addition, a programme for validating the procedures of Antarctic organisms storage by checking the stability of some chemical parameters both in fresh and freeze-dried specimens has been developed. 相似文献
50.
Dr. Ángel J. Jiménez Michael Sekita Dr. Esmeralda Caballero Dr. M. Luisa Marcos Dr. M. Salomé Rodríguez‐Morgade Prof. Dr. Dirk M. Guldi Prof. Tomás Torres 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(43):14506-14514
In a novel electron‐donor–acceptor conjugate, phthalocyanine (Pc) and perylenediimide (PDI) are connected through a trans‐platinum(II) diacetylide linker to yield Pc‐Pt‐PDI 1 . In the ground state, the presence of PtII disrupts the electronic communication between the two electroactive components, as revealed by UV/Vis spectroscopy and electrochemical studies. The photophysical behavior of 1 is compared with that of the corresponding Pc‐PDI electron‐donor–acceptor conjugate 2 in terms of charge separation and charge recombination. The insertion of PtII between Pc and PDI impacts the results in a longer‐lived Pc . +/PDI . ? radical ion‐pair state. In addition, the intermediately formed Pc triplet excited state is formed with higher quantum yields in 1 than in 2 . 相似文献