1233-73-4Relevant academic research and scientific papers
Excited state kinetics in crystalline solids: Self-quenching in nanocrystals of 4,4′-disubstituted benzophenone triplets occurs by a reductive quenching mechanism
Kuzmanich, Gregory,Simoncelli, Sabrina,Gard, Matthew N.,Spaenig, Fabian,Henderson, Bryana L.,Guldi, Dirk M.,Garcia-Garibay, Miguel A.
, p. 17296 - 17306 (2011)
We report an efficient triplet state self-quenching mechanism in crystals of eight benzophenones, which included the parent structure (1), six 4,4′-disubstituted compounds with NH2 (2), NMe2 (3), OH (4), OMe (5), COOH (6), and COOMe (7), and benzophenone-3,3′,4, 4′-tetracarboxylic dianhydride (8). Self-quenching effects were determined by measuring their triplet-triplet lifetimes and spectra using femtosecond and nanosecond transient absorption measurements with nanocrystalline suspensions. When possible, triplet lifetimes were confirmed by measuring the phosphorescence lifetimes and with the help of diffusion-limited quenching with iodide ions. We were surprised to discover that the triplet lifetimes of substituted benzophenones in crystals vary over 9 orders of magnitude from ca. 62 ps to 1 ms. In contrast to nanocrystalline suspensions, the lifetimes in solution only vary over 3 orders of magnitude (1-1000 μs). Analysis of the rate constants of quenching show that the more electron-rich benzophenones are the most efficiently deactivated such that there is an excellent correlation, ρ = -2.85, between the triplet quenching rate constants and the Hammet θ+ values for the 4,4′ substituents. Several crystal structures indicate the existence of near-neighbor arrangements that deviate from the proposed ideal for "n-type" quenching, suggesting that charge transfer quenching is mediated by a relatively loose arrangement.
Palladium nanoparticles on amino-modified silica-catalyzed C–C bond formation with carbonyl insertion
Etemadi-Davan, Elham,Khalili, Dariush,Banazadeh, Ali Reza,Sadri, Ghazal,Arshad, Pourya
, p. 1891 - 1903 (2021/02/01)
Abstract: A practical and heterogeneously catalyzed Stille, homo-coupling, and Suzuki carbonylation reaction has been reported using Pd nanoparticles supported on amino-vinyl silica-functionalized magnetic carbon nanotube (CNT@Fe3O4@SiO2-Pd) for the efficient synthesis of symmetrical and unsymmetrical diaryl ketones from aryl iodides. A wide variety of symmetrical and unsymmetrical diaryl ketones were obtained in high yields under CO gas-free conditions using Mo(CO)6 as an efficient carbonyl source. Considering the atom economy of Ph3SnCl, less than an equimolar amount can be applied in Stille transformation, which is of great importance due to the toxicity of organotin derivatives. Moreover, no phosphine ligand and external reducing agent were necessary in these coupling carbonylation reactions. This heterogeneous Pd catalyst offers high activity with very low palladium leaching. Finally, the catalyst can be reused and recycled for six steps without loss in activity, exhibiting good example of sustainable methodology. Graphic abstract: [Figure not available: see fulltext.].
Method for preparing symmetric diarylketone through catalytic oxidative carbonylation
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Paragraph 0023; 0024; 0025; 0026; 0029, (2019/03/08)
The invention discloses a method for preparing symmetric diarylketone of a formula (I) as shown in the description. The method comprises the following steps: mixing arylboronic acid (II) (Ar-B(OH)2 (II)), a palladium catalyst, a promoter and an organic solvent in a reactor, introducing air and CO having a volume ratio of (7-19):1, reacting under the conditions of a pressure of 1-6 atm and a temperature of 30-80 DEG C for 8-16 hours, and performing after-treatment on the reaction solution, thereby obtaining the product symmetric diarylketone. According to the method disclosed by the invention,the air directly serves as an oxidizing agent to replace the O2 to be applied to oxidative carbonylation of the arylboronic acid, and the ratio of the air to CO is beyond an explosion limit. Therefore, the catalytic system is safe and economic. The palladium catalyst is small in dosage and simple in separation and can be recycled for several times. The method disclosed by the invention is mild inreaction condition, excellent in substrate suitability and high in yield.
Intramolecular [4 + 2] trapping of a hexadehydro-diels-alder (HDDA) benzyne by tethered arenes
Pogula, Vedamayee D.,Wang, Tao,Hoye, Thomas R.
supporting information, p. 856 - 859 (2015/03/30)
We report here the efficient, intramolecular trapping in a Diels-Alder (DA) sense of thermally generated benzynes by one of two pendant arene rings. A more electron-rich ring (p-methoxyphenyl) reacted substantially faster than a simple phenyl ring, which was, in turn, slightly more reactive vs a 4-carbomethoxyphenyl ring. Photoinduced di-π-methane rearrangement of the initial DA adducts gave rise to unusual isomeric polycyclic adducts.
Phosphine ligand triggered oxidative decarbonylative homocoupling of aromatic aldehydes: Selectively generating biaryls and diarylketones
Yang, Luo,Zeng, Tieqiang,Shuai, Qi,Guo, Xiangyu,Li, Chao-Jun
supporting information; experimental part, p. 2161 - 2163 (2011/03/22)
A novel rhodium-catalyzed oxidative decarbonylative homocoupling of aromatic aldehydes to generate biaryls and diarylketones selectively and efficiently, triggered by the choice of different phosphine ligands.
Non-Glycosidic and Non-Peptidic Select Inhibitors, and the Use Thereof
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, (2008/06/13)
A new class of non-glycosidic and non-peptidic inhibitors of selectins with low molecular weight according to the general formula 1 is described, as well as methods for their production. These compounds represent a new class of non-toxic, in vivo anti-inf
A novel class of potent nonglycosidic and nonpeptidic pan-selectin inhibitors
Ulbrich, Holger K.,Luxenburger, Andreas,Prech, Philip,Eriksson, Einar E.,Soehnlein, Oliver,Rotzius, Pierre,Lindbom, Lennart,Dannhardt, Gerd
, p. 5988 - 5999 (2007/10/03)
An early step of the inflammatory response, the rolling of leukocytes on activated endothelial cells, is mediated by selectin/carbohydrate interactions. The tetrasaccharide sialy LewisX is a ligand for E-, P-, and L-selectin and therefore serve
NON-GLYCOSIDIC AND NON-PEPTIDIC SELECT INHIBITORS, AND THE USE THEREOF
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Page/Page column 26-27, (2008/06/13)
The invention relates to a category of non-glycosidic and non-peptidic select inhibitors of general formula (1), with a low molecular weight, and to a method for the production thereof. Said category is a category of non-toxic select inhibitors having an
EPR, 1H, and 13C ENDOR Studies of a Quintet-State 13C-Labeled Galvinoxyl-Type Tetraradical
Kirste, Burkhard,Grimm, Michael,Kurreck, Harry
, p. 108 - 114 (2007/10/02)
The syntheses of unlabeled and fourfold 13C-labeled tetraphenylmethane tetrakisgalvinols are described.Different paramagnetic species, i.e., a double-state monoradical, a triplet-state biradical, a quartet-state triradical, a quintet-state tetraradical, c
