We describe here the direct connection between the molecular conformation of a conjugated macrocycle and its macroscopic charge transport properties. We incorporate chiral, helical perylene diimide ribbons into the two separate macrocycles as the n-type, electron transporting material. As the macrocycles' films and electronic structures are analogous, the important finding is that the macrocycles' molecular structures and their associated dynamics determine device performance in organic field effect transistors. We show the more flexible macrocycle has a 4-fold increase in electron mobility in field effect transistor devices. Using a combination of spectroscopy and density functional theory calculations, we find that the origin of the difference in device performance is the ability of more flexible isomer to make intermolecular contacts relative to the more rigid counterpart.
This work presents a synergy between organic electronics and supramolecular chemistry, in which a host–guest complex is designed to function as an efficacious electronic material. Specifically, the noncovalent recognition of a fullerene, phenyl‐C61‐butyric acid methyl ester (PC61BM), by an alternating perylene diimide (P)‐bithiophene (B) conjugated macrocycle (PBPB) results in a greater than five‐fold enhancement in electron mobility, relative to the macrocycle alone. Characterization and quantification of the binding of fullerenes by host PBPB is provided alongside evidence for intermolecular electronic communication within the host–guest complexes.
Most elastomers undergo strain‐induced crystallization (SIC) under tension; as individual chains are held rigidly in a fixed position by an applied strain, their alignment along the strain field results in a shift from strain‐hardening (SH) to SIC. A similar degree of stretching is associated with the tension necessary to accelerate mechanically‐coupled, covalent chemical responses of mechanophores in overstretched chains, raising the possibility of an interplay between the macroscopic response of SIC, and the molecular response of mechanophore activation. Here we report thiol‐yne‐derived stereoelastomers, doped covalently with a dipropiolate‐derivatized spiropyran (SP) mechanophore (0.25‐0.38 mol%). Material properties of SP‐containing films are consistent with undoped controls, indicating that the SP behaves as a reporter of the mechanical state of the polymer film. Uniaxial tensile tests reveal correlations between mechanochromism and SIC, which are strain rate‐dependent. Potential consequences of the correlations between mechanochromism and SIC include the possibility that mechanochromophores may provide a pathway to bridge these phenomena, since molecular‐level mechanochemical activation results in a macroscopic color change in the bulk material. When mechanochromic films are stretched slowly to the point of mechanophore activation, the covalently tethered mechanophore remains trapped in a force‐activated state, even after the applied stress is removed. Additionally, the kinetics of mechanophore reversion correlate with the applied strain rate, resulting in highly tunable decoloration rates. Because these polymers are not covalently cross‐linked, they can be recycled by melt‐pressing into new films, which increases their potential range of strain‐sensing, morphology‐sensing, and shape‐memory applications.This article is protected by copyright. All rights reserved
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