2020 Volume 93 Issue 1 Pages 99-108
Trioxa- and trithia-truxene derivatives, 3,8,13- (para) and 2,7,12- (meta) tri-tert-butylated benzo[1,2-b:3,4-b′:5,6-b′′]-trifuran and -trisbenzothiophenes (p-tBuTxO, m-tBuTxO, p-tBuTxS, and m-tBuTxS), have been prepared by palladium-catalyzed intramolecular triple dehydrogenative cyclization. While these compounds are soluble in common organic solvents, they have high melting points, mostly more than 300 °C. m-tBuTxO shows a substantial solid state UV fluorescence with a higher quantum efficiency than p-tBuTxO. Both p-tBuTxS and m-tBuTxS, however, exhibit only weak fluorescence in both solution and solid state (the λmax of emission in solid state specifically depends on the substitution pattern), but obvious blue phosphorescence is observed in PMMA film under vacuum at r.t. as well as in MeCy at 77 K, which is attributable to the heavy atom effect of sulfur. Meanwhile, p-tBuTxS exhibits a higher hole mobility compared with that of m-tBuTxS in the evaluation of thin-film FET characteristics. These results are discussed in terms of intrinsic molecular structures and arrangements determined by X-ray crystallography.
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