870259-00-0Relevant articles and documents
Pyrene as chromophore and electrophore: Encapsulation in a rigid polyphenylene shell
Bernhardt, Stefan,Kastler, Marcel,Enkelmann, Volker,Baumgarten, Martin,Muellen, Klaus
, p. 6117 - 6128 (2006)
Starting from the fourfold ethynyl-substituted chromophore 1,3,6,8-tetraethynylpyrene as core, a series of polyphenylene dendrimers was prepared in high yield by combining divergent and convergent growth methods. The fluorescence quantum yields (Qf>0.92) of the encapsulated pyrene chromophore were independent of the size of the polyphenylene shell. Fluorescence quenching studies and temperature-dependent fluorescence spectroscopy were performed to investigate the site isolation of the core. They indicate that a second-generation dendrimer layer is needed to efficiently shield the encapsulated pyrene and prevent aggregate formation. Alkalimetal reduction of the encapsulated pyrene core was carried out to afford the corresponding pyrene radical anions, for which hampered electron transfer to the core was observed with increasing dendrimer generation, which is further proof of the site isolation due to the polyphenylene shell. To improve film formation and solubility of the material, solubilizing alkyl chains were introduced on the periphery of the spherical particles. Furthermore, highly transparent films obtained by a simple drop-casting method showed blue emission mainly from the unaggregated species. The materials presented herein combine high quantum efficiency, good solubility, and improved film-forming properties, which make them possible candidates for several applications in electronic devices.
Photophysical properties of 1,3,6,8-tetraarylpyrenes and their cation radicals
Vyas, Vijay S.,Lindeman, Sergey V.,Rathore, Rajendra
, p. 209 - 218 (2019/03/02)
The synthesis of 1,3,6,8-tetraaryl substituted pyrenes is described. The substituents on the aryl groups influence the optoelectronic properties of the pyrene core indicating a strong coupling between the aryl groups and the pyrene core. Electronic absroption spectra of the cation radicals generated in solution by the single electron oxidation of pyrenes reaffirmed the coupling of the aryl rings with the pyrene. The aryl groups at 1,3,6,8-positions completely inhibit the π-stacking of pyrene core in solution. Crystal structure of the cation radical salt of tetraphenyl shows charge delocalization between neutral pyrene unit and two cationic pyrene cores. Complete inhibition of the pyrene core stacking is observed in the solid state of cation radical when the dendritic pentaphenyl groups surround the pyrene core.
Synthesis, absorption, and fluorescence-emission properties of 1,3,6,8-tetraethynylpyrene and its derivatives
Venkataramana, Gandikota,Sankararaman, Sethuraman
, p. 4162 - 4166 (2007/10/03)
The synthesis of several 1,3,6,8-tetraethynylpyrene derivatives is reported. The effect of extended acetylenic conjugation on their absorption and fluorescence-emission properties is studied. Significant bathochromic shifts of both the absorption and fluorescence emission bands are observed. These derivatives emit fluorescence in the visible (400-550 nm) region. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
