1232693-10-5Relevant articles and documents
Engineering the Interconnecting Position of Star-Shaped Donor–π–Acceptor Molecules Based on Triazine, Spirofluorene, and Triphenylamine Moieties for Color Tuning from Deep Blue to Green
Wang, Yafei,Liu, Wanhui,Deng, Jiyong,Xie, Guohua,Liao, Yuanwei,Qu, Zuoming,Tan, Hua,Liu, Yu,Zhu, Weiguo
, p. 2555 - 2563 (2016)
Pi-conjugated organic molecules featuring the donor–bridge–acceptor (D–π–A) structure have been widely used in semiconducting materials owing to their rigid structure, good thermal stability, excellent charge transfer, and high emission efficiency. To investigate the effect of the D–π–A molecular structure on the photophysical properties, in this contribution, three star-shaped D–π–A isomers based on the 2,4,6-triphenyl-1,3,5-triazine, spirofluorene, and triphenylamine moieties, that is, p-TFTPA, mp-TFTPA, and m-TFTPA, were synthesized by elaborately engineering the interconnecting position in the building-block units. The optophysical properties of these compounds were systematically explored by experiments and theory calculations. Definitively, changing the interconnecting position in these molecules played a significant role in the degree of π conjugation, which resulted in tunable emission colors from deep blue to green. Moreover, these isomers were employed as emissive dopants in organic light-emitting diodes. The highest external quantum efficiency of 2.3 % and current efficiency of 6.2 cd A?1 were achieved by using the p-TFTPA based device. This research demonstrates a feasible way to realize blue emitters by engineering D–π–A conjugation.
The pyridyldiisopropylsilyl group: A masked functionality and directing group for monoselective ortho-Acyloxylation and ortho-Halogenation reactions of arenes
Huang, Chunhui,Chernyak, Natalia,Dudnik, Alexander S.,Gevorgyan, Vladimir
, p. 1285 - 1305 (2011/07/07)
A novel, easily removable and modifiable silicon-tethered pyridyldiisopropylsilyl directing group for C-H functionalizations of arenes has been developed. The installation of the pyridyldiisopropylsilyl group can efficiently be achieved via two complementary routes using easily available 2-(diisopropylsilyl)pyridine (5). The first strategy features a nucleophilic hydride substitution at the silicon atom in 5 with aryllithium reagents generated in situ from the corresponding aryl bromides or iodides. The second milder route exploits a highly efficient room-temperature rhodium(I)-catalyzed cross-coupling reaction between 5 and aryl iodides. The latter approach can be applied to the preparation of a wide range of pyridyldiisopropylsilyl- substituted arenes possessing a variety of functional groups, including those incompatible with organometallic reagents. The pyridyldiisopropylsilyl directing group allows for a highly efficient, regioselective palladium(II)-catalyzed mono-ortho-acyloxylation and ortho-halogenation of various aromatic compounds. Most importantly, the silicon-tethered directing group in both acyloxylated and halogenated products can easily be removed or efficiently converted into an array of other valuable functionalities. These transformations include protio-, deuterio-, halo-, boro-, and alkynyldesilylations, as well as a conversion of the directing group into the hydroxy functionality. In addition, the construction of aryl-aryl bonds via the Hiyama-Denmark cross-coupling reaction is feasible for the acetoxylated products. Moreover, the ortho-halogenated pyridyldiisopropylsilylarenes, bearing both nucleophilic pyridyldiisopropylsilyl and electrophilic aryl halide moieties, represent synthetically attractive 1,2-ambiphiles. A unique reactivity of these ambiphiles has been demonstrated in efficient syntheses of arylenediyne and benzosilole derivatives, as well as in a facile generation of benzyne. In addition, preliminary mechanistic studies of the acyloxylation and halogenation reactions have been performed. A trinuclear palladacycle intermediate has been isolated from a stoichiometric reaction between diisopropyl(phenyl)pyrid-2-ylsilane (3a) and palladium acetate. Furthermore, both C-H functionalization reactions exhibited equally high values of the intramolecular primary kinetic isotope effect (kH/k D=6.7). Based on these observations, a general mechanism involving the formation of a palladacycle via a C-H activation process as the rate-determining step has been proposed.
A general strategy toward aromatic 1,2-ambiphilic synthons: Palladium-catalyzed ortho-halogenation of PyDipSi-arenes
Dudnik, Alexander S.,Chernyak, Natalia,Huang, Chunhui,Gevorgyan, Vladimir
supporting information; experimental part, p. 8729 - 8732 (2011/01/06)
A general and efficient strategy to synthesize 1,2-ambiphilic aromatic and heteroaromatic synthons from haloarenes has been developed. The method involves installation of the PyDipSi directing group, and subsequent palladium-catalyzed directed ortho-halogenation of aryl silanes (see scheme; Py=2-pyridyl). The usefulness of these 1,2-ambiphilic building blocks was shown in their participation as both nucleophilic aryl silane and electrophilic aryl iodide moieties.
