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We herein present four highly fluorescent and stable D-π-D monomers (2), which were designed and synthesized using different types of aryl substituent as the donor via a Suzuki-Miyaura coupling reaction. We have studied these four symmetrical chromophores by UV-vis absorption and fluorescence emission spectroscopy both in solution and the solid state. This research shows that the introduction of the aryl groups can effectively extend the conjugation length of thiophene chromophore resulting in a shift of the wavelength of the absorption and fluorescence emission and an improvement of the fluorescence quantum yields. The notable optical features of their solid-state powders also exhibited a distinct red-shift in comparison with the emissions of their dilute solutions. These results combined with the theoretical calculations (B3LYP/6-31G*) indicate that these systems are promising candidates in the fabrication of organic electroluminescence devices.

This article presents a set of extended π‐conjugated pyrene derivatives, namely 1,3‐di(arylethynyl)‐7‐tert‐butylpyrenes, which were synthesized by a Pd‐catalyzed Sonogashira coupling reaction of 1,3‐dibromo‐7‐tert‐butylpyrenes with the corresponding arylethynyl group in good yields. Despite the presence of the tert‐butyl group located at the 7‐position of pyrene, X‐ray crystallographic analyses show that the planarity of the Y‐shaped molecules still exhibits strong face‐to‐face π‐π stacking in the solid state; all of the compounds exhibit blue or green emission with high quantum yields (QYs) in dichloromethane. DFT calculations and electrochemistry revealed that this category of compound possesses hole‐transporting characteristics. In addition, with strong electron‐donating (‐N(CH3)2) or electron‐withdrawing (‐CHO) groups in 2 d or 2 f, these molecules displayed efficient intramolecular charge‐transfer (ICT) emissions with solvatochromic shifts from blue to yellow (green) on increasing the solvent polarity. Furthermore, the compounds 2 d and 2 f possess strong CT characteristics.