Synthesis of new conjugated organic molecules with light emission properties that can be manipulated by making structural or solvent polarity changes is important to the field of molecular electronics.  In recent years, our group has explored the synthesis and photophysical properties of molecules containing quinoxaline rings (electron acceptors) that are substituted with electron donors, such as thiophene or bithiophene.  These donor-acceptor chromophores were highly fluorescent and exhibited a strong, positive solvatochromism.  In addition to solvent polarity, the absorption and emission properties of these chromophores can be altered by overlapping them to varying degrees.  This was accomplished by synthesizing two diastereomers where the chromophores are suspended from a rigid aliphatic scaffold that holds the quinoxaline rings together, but the donors either overlap or are separated.  The unique geometry of these diastereomers was shown to facilitate a variable degree of pi-stacking interactions in the ground state and in the excited state.  This led to differences in their photophysical properties compared to one another and compared to those of a single donor-acceptor chromophore.  Our progress toward extending this work to fluorene-substituted quinoxaline analogs will be presented, including the synthesis, NMR spectroscopy, and photophysical studies.

Synthesis and photophysical studies of solvatochromic compounds containing fluorene-quinoxaline donor-acceptor chromophores

253rd National Meeting (2017)

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