Tolyl-Substituted Siloles: Synthesis, Substituent Effects, and Aggregation-Induced Emission

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Journal of Inorganic and Organometallic Polymeric Materials


Silole, Aggrigration induced emission, Luminescence, Substituent effects


The syntheses, spectroscopic characteristics, and electrochemical behavior of 1,1-dimethyl-2,5-diphenyl-3,4-bis(p-methylphenyl)silole and 1,1-dimethyl-2,3,4,5-tetra(p-methylphenyl)silole are reported. The compounds are weakly luminescent in dilute fluid solution but exhibit dramatic aggregation-induced emission (AIE). Absorbance, luminescence, and voltammetric characteristics are compared to 1,1-dimethyl-2,3,4,5-tetraphenylsilole and 1,1-dimethyl-3,4-diphenyl-2,5-bis(p-methylphenyl)silole, allowing a comparison of the effects of the position of the substituents on the silole ring. In addition, HOMO and LUMO energies and band gaps, derived from electrochemical, spectroscopic, and computational data, are reported. Substitution of the weakly electron-donating p-methyl groups on the peripheral aryl groups at the 2- and 5-positions of the silole ring results in slight red shifts in absorption and emission maxima, slight enhancement of luminescence quantum yields, slightly longer luminescence lifetimes, and more anodic oxidation potentials.


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The financial support of the National Science Foundation (NSF #CHE-0808813 and #CHE-0923028), NASA, through the Maine Space Grant Consortium Undergraduate Research Scholarship Program, the University of New England (UNE), and the University of Southern Maine (USM) made this work possible.