Alteration of native gelation properties of anthracene and pyrene cored first generation poly (aryl ether) dendrons, G1-An & G1-Py, by introducing a common acceptor, 2,4,7-trinitro-9H-fluoren-9-one (TNF), results in forming charge transfer gels in long chain alcoholic solvents. This strategy leads to significant perturbation of optical and electronic properties within the gel matrix. Consequently, a noticeable increase of their electrical conductivities is observed, making these poly (aryl ether) dendron based gels as potential candidates for organic electronics. While the dc-conductivity (σ) value for the native gel from G1-An is 2.8 × 10-4 S m-1, the value increased three times (s = 8.7 × 10-4 S m-1) for its corresponding charge transfer gel. Further, the dc-conductivity for the native gel self-assembled from G1-Py dramatically enhanced by approximately an order of magnitude from 4.9 × 10-4 S m-1 to 1.3 × 10-3 S m-1, under the influence of an acceptor. Apart from H-bonding and π---π interactions, charge transfer results in the formation of robust 3D network of fibers, with improved aspect ratio, providing high thermo-mechanical stability to the gels compared to the native ones. The charge transfer gels self-assembled from G1-An / TNF (1:1) and G1-Py / TNF (1:1) exhibits 7.3 and 2.5 fold increase in their yield stress, respectively, compared to their native assemblies. Similar trend follows in case of their thermal stabilities. This attributes to the typical bilayer self-assembly of the former which is not present in the case of G1-Py / TNF charge transfer gel. Density functional calculations provide deeper insights accounting for the role of charge transfer interactions in the mode of self-assembly. The 1D potential energy surface for the G1-An / TNF dimer and G1-Py / TNF dimer is found to be 11.8 kcal mol-1 and 1.9 kcal mol-1 more stable than their corresponding native gel dimers, G1-An / G1-An and G1-Py / G1-Py, respectively.

Charge transfer modulated self-assembly in poly (aryl) ether dendron derivatives with improved stability and transport characteristics

253rd National Meeting (2017)

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