Self-assembly of planar macrocycles leads to a class of organic crystals containing a molecular scale one-dimensional (1D) channel, into which guest molecules can be incorporated to form a host-guest complex. The confinement of guest molecules inside a 1D channel can lead to several benefits, such as controlling the selectivity of reactions among the guest molecules, improvement of light emission properties of fluorescent guests through reduction of aggregation of the guest molecules, facilitating exchange of guests through 1D transport, and controlling conductivity in the host through charge-transfer doping by guests. The orientations of guest molecules in a subnanoscale channel is an important factor to control reaction selectivity, energy transfer, and charge transfer among the guest molecules. Understanding the arrangement of guest molecules in the host channel can facilitate the improved control of these processes. In this study, we incorporated 5-(Dimethylamino)-5’-nitro-2,2-bithiophene into well-defined columnar channels located in a self-assembled structure of phenylethynylene bis-urea macrocycle to form a host-guest complex, and measured the orientation of the fluorescent guest confined in the channel using polarimetric fluorescence microscopy and image analysis. Additionally, we computed the optimized structure of the guest molecules in the host channel. This presentation will discuss measurement procedures, the results from the measurements indicating the orientation of the guests, and compare the results to the computational model of the guests in the host channel.

Polarization anisotropy measurements for determining the orientation of guest molecules in a self-assembled bis-urea macrocycle host

253rd National Meeting (2017)

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