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

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.