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51.
Jian Fang Evan M. Howard Prof. Dr. Matthias Brewer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12927-12931
Structurally complex diazo-containing scaffolds are formed by conjugate addition to vinyl diazonium salts. The electrophile, a little studied α-diazonium-α,β-unsaturated carbonyl compound, is formed at low temperature under mild conditions by treating β-hydroxy-α-diazo carbonyls with Sc(OTf)3. Conjugate addition occurs selectively at the 3-position of indole to give α-diazo-β-indole carbonyls, and enoxy silanes react to give 2-diazo-1,4-dicarbonyl products. These reactions result in the formation of tertiary and quaternary centers, and give products that would be otherwise difficult to form. Importantly, the diazo functional group is retained within the molecule for future manipulation. Treating an α-diazo ester indole addition product with Rh2(OAc)4 caused a rearrangement to occur to give a 2-(1H-indol-3-yl)-2-enoate. In the case of diazo ketone compounds, this shift occurred spontaneously on prolonged exposure to the Lewis acidic reaction conditions. 相似文献
52.
Attempts to synthesize complexes of group 6 carbonyl compounds [M(CO)6] (M = Cr, Mo, W) with the carbone C(PPh3)2 ( 1 ) via the photo chemically created adducts [(CO)5M(THF)] lead to quantitative formation of the salts [HC(PPh3)2]2[M2(CO)10] ( 2 , Cr; 3 , Mo; 4 , W). Alternatively, a long-time thermal reaction of [Mo(CO)6] performed with 1 in THF generates a series of products initiated by a Wittig-type reaction. In addition to 3 , minor amounts of [(CO)5MoCCPPh3] ( 8 ), [(CO)5MoO2CC{PPh3}2] ( 5 ), and the carbonate complexes [HC(PPh3)2]2[(CO)5Mo(CO3)Mo(CO)4] ( 6 ) and [HC(PPh3)2]2[(CO)4Mo(CO3)Mo(CO)4] ( 7 ) were found. Compounds 2 , 3 , 5 , 6 , and 7 were characterized by X-ray analyses, 31P NMR, and IR spectroscopy. The water, necessary for the formation of the carbonate, stems from decomposition of THF. 相似文献
53.
54.
Joanna Klebeko Paula Ossowicz-Rupniewska Ewelina
witek Joanna Szachnowska Ewa Janus Stefka G. Taneva Elena Krachmarova Maya Guncheva 《Molecules (Basel, Switzerland)》2022,27(1)
In recent years, numerous studies have shown that conversion of conventional drugs in ionic liquid (IL) formulation could be a successful strategy to improve their physicochemical properties or suggest a new route of administration. We report the synthesis and detailed characterization of eight salicylic acid-based ILs (SA-ILs) containing cation non-polar or aromatic amino acid esters. Using in vitro assays, we preliminary evaluated the therapeutic potency of the novel SA-ILs. We observed that conversion of the SA into ionic liquids led to a decrease in its cytotoxicity toward NIH/3T3 murine embryo fibroblasts and human HaCaT keratinocytes. It should be mentioned is that all amino acid alkyl ester salicylates [AAOR][SA] inhibit the production of the proinflammatory cytokine IL-6 in LPS-stimulated keratinocytes. Moreover, keratinocytes, pretreated with [PheOMe][SA] and [PheOPr][SA] seem to be protected from LPS-induced inflammation. Finally, the novel compounds exhibit a similar binding affinity to bovine serum albumin (BSA) as the parent SA, suggesting a similar pharmacokinetic profile. These preliminary results indicate that SA-ILs, especially those with [PheOMe], [PheOPr], and [ValOiPr] cation, have the potential to be further investigated as novel topical agents for chronic skin diseases such as psoriasis and acne vulgaris. 相似文献
55.
Maya M. Zaharieva Lyudmila L. Dimitrova Stanislav Philipov Ivanka Nikolova Neli Vilhelmova Petar Grozdanov Nadya Nikolova Milena Popova Vassya Bankova Spiro M. Konstantinov Dimitrina Zheleva-Dimitrova Hristo M. Najdenski 《Molecules (Basel, Switzerland)》2022,27(1)
This study evaluated the in vitro antineoplastic and antiviral potential and in vivo toxicity of twelve extracts with different polarity obtained from the herbaceous perennial plant Geum urbanum L. (Rosaceae). In vitro cytotoxicity was determined by ISO 10993-5/2009 on bladder cancer, (T-24 and BC-3C), liver carcinoma (HEP-G2) and normal embryonic kidney (HEK-293) cell lines. The antineoplastic activity was elucidated through assays of cell clonogenicity, apoptosis induction, nuclear factor kappa B p65 (NFκB p65) activation and total glutathione levels. Neutral red uptake study was applied for antiviral activity. The most promising G. urbanum extract was analyzed by UHPLC–HRMS. The acute in vivo toxicity analysis was carried out following OEDC 423. The ethyl acetate extract of aerial parts (EtOAc-AP) exhibited the strongest antineoplastic activity on bladder cancer cell lines (IC50 = 21.33–25.28 µg/mL) by inducing apoptosis and inhibiting NFκB p65 and cell clonogenicity. EtOAc and n-butanol extracts showed moderate antiviral activity against human adenovirus type 5 and human simplex virus type I. Seventy four secondary metabolites (gallic and ellagic acid derivatives, phenolic acids, flavonoids, etc.) were identified in EtOAc-AP by UHPLC–HRMS. This extract induced no signs of acute toxicity in liver and kidney specimens of H-albino mice in doses up to 210 mg/kg. In conclusion, our study contributes substantially to the detailed pharmacological characterization of G. urbanum, thus helping the development of health-promoting phytopreparations. 相似文献
56.
This review summarizes recent developments made in the incorporation of functional materials into organic polymer monoliths, together with new monolithic forms and formats, which enhance their application as supports and stationary phase materials for sample preparation and chromatographic separations. While polymer monoliths are well‐known supports for the separation of large molecules, recent developments have been made to improve their features for the separation of small molecules. The selectivity and performance of organic polymer monoliths has been improved by the incorporation of different materials, such as metal‐organic frameworks, covalent organic frameworks, or other types of nanostructured materials (carbon nanohorns, nanodiamonds, polyoxometalates, layered double hydroxides, or attapulgite). The surface area of polymer monoliths has been significantly increased by polymer hypercrosslinking, resulting in increased efficiency when applied to the separation of small molecules. In addition, recent exploration of less conventional supports for casting polymer monoliths, including photonic fibres and 3D printed materials, has opened new avenues for the applications of polymer monoliths in the field of separation science. Recent developments made in these topics are covered, focusing on the strategies followed by the authors to prepare the polymer monoliths and the effect of these modifications on the developed analytical applications. 相似文献
57.
Feng Li Melisa Rodas Ceballos Sepideh Keshan Balavandy Jingxi Fan Mohammad Mahdi Khataei Yadollah Yamini Fernando Maya 《Journal of separation science》2020,43(9-10):1854-1866
In the last 5 years, additive manufacturing (three‐dimensional printing) has emerged as a highly valuable technology to advance the field of analytical sample preparation. Three‐dimensional printing enabled the cost‐effective and rapid fabrication of devices for sample preparation, especially in flow‐based mode, opening new possibilities for the development of automated analytical methods. Recent advances involve membrane‐based three‐dimensional printed separation devices fabricated by print‐pause‐print and multi‐material three‐dimensional printing, or improved three‐dimensional printed holders for solid‐phase extraction containing sorbent bead packings, extraction disks, fibers, and magnetic particles. Other recent developments rely on the direct three‐dimensional printing of extraction sorbents, the functionalization of commercial three‐dimensional printable resins, or the coating of three‐dimensional printed devices with functional micro/nanomaterials. In addition, improved devices for liquid–liquid extraction such as extraction chambers, or phase separators are opening new possibilities for analytical method development combined with high‐performance liquid chromatography. The present review outlines the current state‐of‐the‐art of three‐dimensional printing in analytical sample preparation. 相似文献
58.
Paloma Begines Sergio Martos Irene Lagunes Ins Maya Jos M. Padrn
scar Lpez Jos G. Fernndez-Bolaos 《Molecules (Basel, Switzerland)》2022,27(4)
Being aware of the enormous biological potential of organoselenium and polyphenolic compounds, we have accomplished the preparation of novel hybrids, combining both pharmacophores in order to obtain new antioxidant and antiproliferative agents. Three different families have been accessed in a straightforward and chemoselective fashion: carbohydrate-containing N-acylisoselenoureas, N-arylisoselenocarbamates and N-arylselenocarbamates. The nature of the organoselenium framework, number and position of phenolic hydroxyl groups and substituents on the aromatic scaffolds afforded valuable structure–activity relationships for the biological assays accomplished: antioxidant properties (antiradical activity, DNA-protective effects, Glutathione peroxidase (GPx) mimicry) and antiproliferative activity. Regarding the antioxidant activity, selenocarbamates 24–27 behaved as excellent mimetics of GPx in the substoichiometric elimination of H2O2 as a Reactive Oxygen Species (ROS) model. Isoselenocarbamates and particularly their selenocarbamate isomers exhibited potent antiproliferative activity against non-small lung cell lines (A549, SW1573) in the low micromolar range, with similar potency to that shown by the chemotherapeutic agent cisplatin (cis-diaminodichloroplatin, CDDP) and occasionally with more potency than etoposide (VP-16). 相似文献
59.
The influence of Cr impurities on muonium atom formation in GaAs has been studied using muon spin relaxation techniques with alternating electric fields. The results suggest that electron transport to and capture by the muon is suppressed by capture/scattering on intervening Cr centers. The length scale involved is estimated to be about 3x10(-6) cm. This offers an opportunity to study electron transport to positive centers in semiconductors on a microscopic scale. 相似文献
60.
Miller RI Kiefl RF Brewer JH Sonier JE Chakhalian J Dunsiger S Morris GD Price AN Bonn DA Hardy WH Liang R 《Physical review letters》2002,88(13):137002
Evidence for static alternating magnetic fields in the vortex cores of underdoped YBa2Cu3O6+x is reported. Muon spin rotation measurements of the internal magnetic field distribution of the vortex state of YBa2Cu3O6.50 in applied fields of H = 1 T and H = 4 T reveal a feature in the high-field tail of the field distribution which is not present in optimally doped YBa2Cu3O6.95 and which fits well to a model with static magnetic fields in the vortex cores. The magnitude of the fields is estimated to be 18(2) G and decreases above T = 10 K. We discuss possible origins of the additional vortex core magnetism within the context of existing theories. 相似文献