Synthesis, Photophysical and Electrochemical Study of 1,3,6,8‐Tetraarylsubstituted X‐Shaped Phenanthrene Derivatives

Abstract

X‐shaped phenanthrene derivatives containing aryl substituents at the 1,3,6,8‐positions were synthesized through Suzuki coupling reactions of two types of phenanthrenes possessing bromine and chlorine substituents. X‐shaped phenanthrenes, with four t‐butylphenyl, 9,9‐dimethyl‐9H‐fluoren‐2‐yl or 4‐diphenylaminophenyl (DPAP) groups, are highly emissive in the blue region and their fluorescence efficiencies increase as the extent of aryl π‐conjugation increases. To assess the effects of donor (D) and acceptor (A) groups at the 1,8‐ and 3,6‐positions on intramolecular charge‐transfer emission, two D−A compounds with two DPAP D‐groups and two 4‐pyridyl (Py) A‐groups were synthesized. Results of electrochemical studies reveal that the phenanthrene with four DPAP groups does not undergo oxidative polymerization in dichloromethane, but the two D−A analogs possessing both DPAP and Py groups do undergo oxidative polymerization, producing films which have electrochromic properties.

Semiconductor Properties of π‐Extended 2‐(Thiopyran‐4‐ylidene)‐1,3‐benzodithiole (TP‐BT) Analogs

“…Moreover, different types of π-extension, i. e., fused and σ-bonded systems, and their substitution positions lead to diverse physical properties. [17][18][19][20][21][22][23][24][25][26][27] In this context, the effect of the π-extension of tetrathiafulvalene (TTF) [28][29][30] and benzothienobenzothiophene (BTBT) derivatives, [31][32][33][34][35][36][37] which are important building blocks for the construction of excellent organic (semi)conductors (Figure 1), on the OFET performance has been investigated from the viewpoints of the oxidation potentials, crystal structures, and thermal stabilities. For example, fused-type π-extended dibenzotetrathiafulvalene (DBTTF) forms two-dimensional (2D) intermolecular interactions and shows a relatively high hole mobility.…”

“…π‐Extension, which is the easiest method for the development of organic semiconductor materials, allows controlling the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs). Moreover, different types of π‐extension, i. e., fused and σ‐bonded systems, and their substitution positions lead to diverse physical properties [17–27] …”