Search results for "thiophene"
showing 10 items of 284 documents
Spectroscopic and theoretical study of push-pull chromophores containing thiophene-based quinonoid structures as electron spacers
2003
Donor−acceptor chromophores containing three different types of thiophene-based electron spacers and the same donor (1,3-dithiol-2-ylidene) and acceptor (dicyanomethylene) end groups have been investigated by infrared and vis-near-IR absorption spectroscopies with the aim of elucidating the ability of the heteroquinonoid spacers as electron transmitters. Density functional theory calculations have been carried out, both within the standard and the time-dependent formalisms, to assign the most relevant electronic and infrared features of these chromophores and to assess useful information about their molecular structures. Both theoretical calculations and vibrational spectra demonstrate the …
Imidazo[2,1-b] [1,3,4]thiadiazoles with antiproliferative activity against primary and gemcitabine-resistant pancreatic cancer cells
2020
A new series of eighteen imidazo [2,1-b] [1,3,4]thiadiazole derivatives was efficiently synthesized and screened for antiproliferative activity against the National Cancer Institute (NCI-60) cell lines panel. Two out of eighteen derivatives, compounds 12a and 12h, showed remarkably cytotoxic activity with the half maximal inhibitory concentration values (IC50) ranging from 0.23 to 11.4 μM, and 0.29–12.2 μM, respectively. However, two additional compounds, 12b and 13g, displayed remarkable in vitro antiproliferative activity against pancreatic ductal adenocarcinoma (PDAC) cell lines, including immortalized (SUIT-2, Capan-1, Panc-1), primary (PDAC-3) and gemcitabine-resistant (Panc-1R), elici…
Thiophen—Mangantricarbonyl-Komplexe
1967
Abstract Cationic thiophenemanganese tricabonyl complexes of the formula [C 4 (CH 3 ) x H 4- x S Mn(CO) 3 ] + have been prepared with 2-methyl-, 3-methyl-, 2,5-dimethyl-, 2,3,5-trimethyl-, tetramethylthiophene, and with thiophene by the reaction of Mn(CO) 5 Cl+AlCl 3 or AlBr 3 with the thiophenes in petrol ether, at 100–110°. The complexions give yellow solutions which are fairly stable. Their IR and some NMR spectra are given and discussed.
Reactive adsorption of thiophene on Ni/ZnO: role of hydrogen pretreatment and nature of the rate determining step.
2008
Abstract Reactive adsorption of thiophene on reduced and unreduced NiO/ZnO adsorbents was studied by thermal gravimetric analysis and by sulfidation in a fixed bed reactor at 330–375 °C and 10–40 mbar of thiophene in hydrogen. The adsorbents (12 wt% Ni) were prepared by co-precipitation of corresponding nitrates with sodium carbonate followed by calcination at 400 °C. We have found that such solids can react with thiophene without any prior reduction. Metallic Ni, indispensable for thiophene decomposition, is formed in this case in situ upon the contact with thiophene/H 2 reaction mixture. The reduction of NiO/ZnO in H 2 (360 °C, 6 h) results in the formation of Ni–Zn alloyed particles (as …
Synergetic effect of gold in Au/Pd catalysts during hydrodesulfurization reactions of model compounds
2003
Abstract The simultaneous formation of colloidal dispersions of Pd and Au metal particles protected by the organic polymer polyvinylpyrrolidone (PVP) in reducing alcohol solution was used for the synthesis of new silica-supported monometallic and bimetallic Au x Pd y catalysts with different x / y ratios. The samples, with a 2 wt% total metal loading, after air calcinations at 673 K to remove the PVP, were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and FTIR spectra of chemisorbed CO. Formation of alloyed Au x Pd y particles of different metal composition with consequent modification of their electronic and geometric properties was ascertained. The catalytic activi…
Effect of Gold on the HDS Activity of Supported Palladium Catalysts
2002
Abstract The effect of gold on palladium catalysts supported on amorphous aluminosilicate was investigated in the hydrodesulfurization of thiophene. A series of bimetallic AuxPdy catalysts was prepared by the slow deposition–precipitation method with decomposition of urea. The structural and surface properties of the samples were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy techniques at different stages of the catalyst life. After calcination at 673 K, gold-enriched solid solutions of approximately Au90Pd10 and Au80Pd20 composition were formed for all samples of different Au/Pd ratios, along with free palladium phases. Au80Pd20 was the prevailing phase. Hydrogen treat…
Hydrogenation of Aromatics in Diesel Fuels on Pt/MCM-41 Catalysts
1997
Abstract The hydrogenation activity of Pt supported on two mesoporous MCM-41 samples differing in their chemical composition has been studied by following the kinetics of the hydrogenation of naphthalene at 225–275°C reaction temperature and 5.0 MPa total pressure and by comparing the kinetic parameters obtained with Pt supported on a mesoporous amorphous silica-alumina (MSA) and other conventional supports, such as commercial amorphous silica-alumina (ASA), zeolite USY, γ-alumina, and silica. The two mesoporous MCM-41 and MSA materials having very high surface areas allowed for a better dispersion of the Pt particles, and they showed a superior overall hydrogenation activity as compared to…
Update on topical carbonic anhydrase inhibitors
2001
Topical carbonic anhydrase inhibitors are a novel addition to the armamentarium of medical glaucoma treatment; dorzolamide has been available since 1995 and brinzolamide since 1998. They lower intraocular pressure by inhibiting carbonic anhydrase, a key enzyme for aqueous humor formation. Intraocular pressure-lowering activity of the substances appears to be the same and is similar to that of most other agents, but it does not reach the activity of the unselective beta-blocker timolol or the prostaglandin latanoprost. On concomitant treatment, additivity is reached with all other topical agents. A possible improvement of blood flow may offer an additional benefit, but its significance for t…
Intercurrent factors associated with the development of open-angle glaucoma in The European Glaucoma Prevention Study
2007
Purpose: To evaluate the intercurrent factors for the development of open-angle glaucoma (OAG) in ocular hypertensive patients who were enrolled in the European Glaucoma Prevention Study (EGPS). Design: Randomized, double masked, controlled clinical trial. Methods: setting: Multicenter. study population: A total of 1,077 patients fulfilled a series of inclusion criteria, including intraocular pressure (IOP) 22 to 29 mm Hg, normal and reliable visual fields (VFs) and normal optic disks. intervention: Treatment with dorzolamide or placebo. main outcome measures: Glaucoma-related VF or optic disk changes. Clinical data were collected every six months during a five-year follow-up. Proportional …
Synthesis of novel antimitotic agents based on 2-amino-3-aroyl-5-(hetero)arylethynyl thiophene derivatives
2011
Microtubules are dynamic structures that play a crucial role in cellular division and are recognized as an important target for cancer therapy. In search of new compounds with strong antiproliferative activity and simple molecular structure, a new series of 2-amino-3-(3',4',5'-trimethoxybenzoyl)-5-(hetero)aryl ethynyl thiophene derivatives was prepared by the Sonogashira coupling reaction of the corresponding 5-bromothiophenes with several (hetero)aryl acetylenes. When these compounds were analyzed in vitro for their inhibition of cell proliferation, the 2- and 3-thiophenyl acetylene derivatives were the most powerful compounds, both of which exerted cytostatic effects at submicromolar conc…