17865-11-1Relevant articles and documents
Electron Transfer around a Molecular Corner
Schmidt, Hauke C.,Larsen, Christopher B.,Wenger, Oliver S.
supporting information, p. 6696 - 6700 (2018/03/26)
The distance dependence of electron transfer (ET) is commonly investigated in linear rigid rod-like compounds, but studies of molecular wires with integrated corners imposing 90° angles are very rare. By using spirobifluorene as a key bridging element and by substituting it at different positions, two isomeric series of donor-bridge-acceptor compounds with either nearly linear or angled geometries were obtained. Photoinduced ET in both series is dominated by rapid through-bond hole hopping across oligofluorene bridges over distances of up to 70 ?. Despite considerable conformational flexibility, direct through-space and through-solvent ET is negligible even in the angled series. The independence of the ET rate constant on the total number of fluorene units in the angled series is attributed to a rate-limiting tunneling step through the spirobifluorene corner. This finding is relevant for multidimensional ET systems and grids in which individual molecular wires are interlinked at 90° angles.
Gold-catalyzed oxidative coupling reactions with aryltrimethylsilanes
Brenzovich Jr., William E.,Brazeau, Jean-Francois,Toste, F. Dean
supporting information; experimental part, p. 4728 - 4731 (2010/12/25)
During continuing studies with a novel oxidative gold oxyarylation reaction, arylsilanes were found to be competent coupling partners, providing further evidence for an intramolecular electrophilic aromatic substitution mechanism. While providing yields complementary to those of the previously described boronic acid methods, the use of trimethylsilanes reduces the observation of homocoupling byproducts and allows for facile intramolecular coupling reactions.
Synthesis and characterization of highly soluble and oxygen permeable new polyimides bearing a noncoplanar twisted biphenyl unit containing tert-butylphenyl or trimethylsilyl phenyl groups
Kim, Hyung-Sun,Kim, Yun-Hi,Ahn, Seung-Kuk,Kwon, Soon-Ki
, p. 2327 - 2332 (2007/10/03)
The two new dianhydrides, 2,2′-bis(4″-tert-butylphenyl)-4,4′,5,5′-biphenyltetracar boxylic dianhydride (BBBPAn) and 2,2′-bis(4″-trimethylsilylphenyl)-4,4′,5,5′-biphenyltetr acarboxylic dianhydride (BTSBPAn), composed of a noncoplanar twisted biphenyl unit containing tert-butylphenyl or trimethylsilyphenyl groups were prepared. Two series of new organosoluble polyimides were prepared from the dianhydride and aromatic diamines by the conventional polyamide acid reaction followed by chemical imidization as well as high-temperature one-step polymerization. The structures of polymers were confirmed by various spectroscopic techniques. The weight-average molecular weight and polydispersities of resulting polymers were in the ranges 60 400-332 400 and 1.87-3.51, respectively. The polyimides showed good solubility in various organic solvents such as chloroform and THF. The polyimides exhibited 5% weight loss at 540-550°C in nitrogen as measured by thermogravimetric analysis. The polyimides showed high Tg's and good mechanical properties. The oxygen permeability coefficient (PO2) and permselectivity of oxygen to nitrogen (PO2/PN2) of the films were in the ranges 31-110 barrer and 2.8-4.3, respectively.
