Optical and electronic properties of siloxane-bridged cyclic dimers with naphthylene or pyrenylene moieties

Synthesis and characterization of poly(tetramethylsilarylenesiloxane) derivatives bearing diphenylfluorene or diphenyldibenzosilole moieties

“…The hyperchromic effects result from the enhancement of the transition moment based on the increase in the dipole moments of the HOMO and LUMO states owing to the s-p conjugation in the HOMO and the s*-p* conjugation in the LUMO. [12][13][14][15][16][17] On the other hand, the 0-0 electronic transition was observed at around 316 nm in the case of silyl-substituted diphenylfluorene derivatives (5, M1 and P1), as shown in Figure 5a, whereas it was observed at around 324 nm in the case of silyl-substituted diphenyldibenzosilole derivatives (6, M2, and P2), as shown in Figure 5b. This bathochromic shift would be due to the stabilization of the LUMO state through s*-p* conjugation induced by the replacement of the C-9 carbon in fluorene by silicon.…”

“…[12][13][14][15][16][17] The bathochromic effect has been known to be induced by lowering the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states because of destabilization of the HOMO state through s-p conjugation and stabilization of the LUMO state through s*-p* conjugation. The hyperchromic effects result from the enhancement of the transition moment based on the increase in the dipole moments of the HOMO and LUMO states owing to the s-p conjugation in the HOMO and the s*-p* conjugation in the LUMO.…”

“…[12][13][14][15][16][17] Kitamura et al 18 reported a polysiloxane having fluorenyl moiety in the main chain; however, the obtained polysiloxane derivative was an oil product owing to the extremely low glass transition temperature (T g ). Thus, the use of polysiloxane derivatives as polymeric OLED materials seems to be inadequate because of their extremely low T g, 19,20 which allows the formation of aggregates and/or interchain excimers to induce the decline of the color stability of light emission.…”

Synthesis and characterization of poly(tetramethylsilarylenesiloxane) derivatives bearing benzodithiophene moieties

“…Furthermore, the incorporation of silyl substituents onto aromatic species has been reported [13][14][15][16][17][18][19][20][21][22] to result in a high fluorescence quantum yield. The use of polysiloxane derivatives as polymeric organic light-emitting diode (OLED) materials appears to be inadequate because of their low glass transition temperatures (T g s) [23,24], which allow the formation of aggregates and/or interchain excimers to induce a decrease in the color stability of light emission.…”

“…One of the methods for increasing the T g is to incorporate bulky and rigid moieties into the main chain [27][28][29][30][31][32][33]. For example, the T g of poly(dimethylsiloxane) has been reported to be À123°C [23]; however, those of a series of poly(tetramethylsilarylenesiloxane) derivatives have been reported to range from À52°C to 191°C depending on the arylene moiety introduced in the main chain [17][18][19][20][28][29][30][31][32][33]. From these points of view, we have reported the synthesis of several poly(tetramethylsilarylenesiloxane) derivatives with pyrene [17], dibenzosilole [19] or cyclopentadithiophene [33] moieties that exhibited high T g s and good thermostability and fluorescence properties.…”