Search

Abstract: Four new well-defined monodisperse linear oligofluorenes with anthracene core An-OFVn (n =1–4) have been synthesized through Heck and Wittig reaction. These conjugated oligomers exhibit good solubility in common organic solvents. It is found that the conjugation length of the oligomers can be extended and the formation of excimers can be suppressed with increasing the number of fluorene–vinylene units linked in the 9,10-positions of anthracene. [Copyright &y& Elsevier]

Abstract: Two porphyrins with oligo-phenothiazine arms have been synthesized by a combination of Heck and Adler reaction, and their photophysical properties have been investigated by absorption and steady-state fluorescence spectroscopy. It is found that the excitation energy transfer occurs from the phenothiazine units to the porphyrin core, and that the porphyrins can emit intense red light with high fluorescent quantum yields. [Copyright &y& Elsevier]

Abstract: A series of linear monodisperse vinylene-linked phenothiazine oligomers have been synthesized by alternate Heck reaction and Wittig reaction in good yields. It was found that their absorption and fluorescence emission bands red-shifted with increasing phenothiazine units due to extending of the conjugated degree. The fluorescent quantum yield increased from OPTZ1 to OPTZ6, and the Φ F of OPTZ6 was close to phenothiazine-based polymers. [Copyright &y& Elsevier]

Abstract: Novel monodisperse linear 3,9-linked oligocarbazoles (OCAs) were prepared stepwise using Ullmann coupling reaction in seal-tubes. The resulting OCAs were soluble in common organic solvents. The UV–vis spectra of OCAs exhibited small red shift and their intensities increased linearly with the increase of the carbazole moieties, suggesting that no intramolecular π-interactions appeared at ⩽8-mer. All the OCAs gave strong fluorescence and it was found that the conjugated degree of linear OCAs would be saturated when the number of carbazole units reaches four. [Copyright &y& Elsevier]

New dimesitylborylthiophene derivative with terminal tetraphenylethene TPETB has been synthesized. It was found that TPETB exhibited aggregation-induced emission behavior and reversible mechanofluorochromism. For instance, the emission intensity of TPETB in THF/H 2 O with water fraction of 90% was ca. 21 times higher than that in THF. In addition, grinding the as-prepared crystal of TPETB the emitting color changed from sky blue to yellowish green. Meanwhile, the ground powder could recover to crystalline structure with sky blue emission when it was exposed to CH 2 Cl 2 vapor. It was suggested that the transformation between crystalline and amorphous states led to the changes of solid emitting colors in response to external mechanical forces. It should be noted that TPETB could detect F − selectively, and the detection limit was 1.67 × 10 −8 mol/L in CH 2 Cl 2 . [ABSTRACT FROM AUTHOR]

Abstract: Two-component organogelators based on a discotic H-bonding donor of 1,3,5-tris(4-amidobutanoic acid)phenyl benzene (2), and acceptors of 4-(4-alkoxybenzoyloxy)-4′-stilbazole derivatives were reported. These complexes showed good gelation ability for alcohols, which are known to be unfavorable for H-bonding formation. SEM study revealed that sheet-like network, nanotapes, and nanorods were gained from the self-assembling of the complexes with small difference of the carbon chain length. Based on XRD, IR, temperature-dependent 1H NMR, and UV–vis absorption investigations, the gel-phase materials were generated from 1D columnar-type packing of complexes facilitated by cooperative H-bonding, π-stacking, and van der Walls interactions. [Copyright &y& Elsevier]

New indolocarbazole derivatives have been synthesized via Cadogan reaction. It has been found that the reductive cyclization of 3-(2-nitrophenyl)carbazoles prefers to take place on 4-position instead of 2-position in carbazole rings. Because electrophilic substitution was one of the main steps in Cadogan reaction and the Fukui function analysis for 9-methyl-3-(2-nitrophenyl)-9 H -carbazole revealed that more positive part of f − ( r ) function was localized at 4-position than at 2-position in carbazole, the 4-position was the favorite reactive site for the reductive cyclization. Such regioselective Cadogan reaction would be useful for the synthesis of π-extended N -fused heteroacenes with desired functionalities. [ABSTRACT FROM AUTHOR]

Abstract: New well-defined monodisperse oligocarbazoles-functionalized anthracenes An-OCZn (n =1, 2, 3) have been synthesized through Suzuki cross-coupling reaction of the brominated oligocarbazoles and 9,10-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)anthracene. They show good solubility in organic solvents, including dichloromethane, chloroform, toluene, ethyl acetate, and tetrahydrofuran. It should be noted that, in the case of An-OCZn, the formation of the excimer based on anthracene unit is suppressed completely due to the introduction of oligocarbazoles in 9,10-position of anthracene so that an intense blue-emitting has been afforded. In addition, the obtained An-OCZn exhibit good electrochemical and thermal stabilities. Thus, the oligocarbazoles-functionalized anthracenes can be a class of promising candidates for novel blue-emitting materials employed in OLEDs or related devices. [Copyright &y& Elsevier]