1,3-diynes are of interest because of their luminescent properties. 4-(trifluoromethoxy)-phenylacetylene was used to prepare a 1,4-diaryl-1,3-diyne derivative with electron-withdrawing trifluoromethoxy substituents, compound 1. 4-ethynlanisole, 3-ethynlanisole, and 2-ethynlanisole were used to prepare 1,4-diaryl-1,3-diyne derivatives with an electron-donating methoxy substituent, compounds 2-4 respectively. Both 4-(trifluoromethoxy)-phenylacetylene and 4-ethynlanisole were used to prepare a 1,4-diaryl-1,3-diyne derivative with both the electron-withdrawing trifluoromethoxy and the electron-donating methoxy substituents, compound 5. The percent yields for compound 2-4 were in the range of 90-96%. The percent yield for compound 1 was 56%. The percent yield compound 5 was not determined, but 60 mg of the compound was obtained from a synthesis that used 25 and 35 mg of the starting materials. The steady state photophysical properties of each compound were assessed in acetonitrile solution at room temperature. Compound 1 had absorption maxima at 247, 288, 306, and 327 nm (ε= 4.72x103, ε= 3.88x104, ε= 4.82x104, ε= 4.64x104, respectively), and an emission maximum at 426 nm. Compound 2 had absorption maxima at 203, 267, 280, 298, 317, and 339nm (ε= 4.17x104, ε= 2.84x104, ε= 2.86x104, ε= 3.18x104, ε= 3.64x104, ε= 3.23x104, respectively), and an emission maximum at 476 nm. Compound 3 had absorption maxima at 213, 258, 312, and 331 nm (ε= 5.69x104, ε= 2.68x104, ε= 2.43x104, ε= 2.42x104, respectively), and a broad emission maximum around 415 nm. Compound 4 had absorption maxima at 208, 259, 325, and 348 nm (ε= 6.98x104, ε= 2.74x104, ε= 3.22x104, ε= 2.95x104, respectively), and emissions maxima at 382 and 354nm. Compound 5 had absorption maxima at 261, 297, 315, and 336 nm (ε= 1.74x104, ε= 2.50x104, ε= 4.33x104, ε= 2.58x104, respectively), and an emission maximum at 438 nm. Steady state data in methylcyclohexane (at room temperature and 77 K) and chloroform (at room temperature) will be presented along with time-resolved photophysical data. TD-DFT studies were done to help understand how the structures of 1-5 relate to their excited state properties.

Synthesis, pohtophysical, and computational studies of a series of 1,4-diaryl-1,3-butadiynes

253rd National Meeting (2017)

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