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Creating new chiral molecular and macromolecular systems that can polarize the spin of electrons has the dual promise of both applications in spintronics and a fundamental understanding of their origins. Here, we put forward two optically active helical ladder dimers from perylene diimide-based twistacenes and helicenes. We detail a scalable method to separate the helices for each of these systems and methods to functionalize them with thiol groups that allow for self-assembled monolayer formation on metal surfaces. We probed these monolayers with conductive atomic force microscopy, revealing that they are highly conductive. If the substrate is magnetized, then the current we measure with conductive atomic force microscopy is controlled by the handedness of the helices used to form the monolayers. Furthermore, helices of the same handedness for either the twistacene or helicene (right-handed helices vs left-handed helices) produce high (or low) currents in devices with the same magnetization. Importantly, we find a correlation between the magnetic field dependence of the conductivity and the helicity of the molecules, suggesting a link between these two properties, independent of the sign of their electronic circular dichroism. 

Abstract In this manuscript, we report the first demonstration of controlled helicity in extended graphene nanoribbons (GNRs). We present a wealth of new graphene nanoribbons that are a direct consequence of the high‐yielding and robust synthetic method revealed in this study. We created a series of defect‐free, ultralong, chiral cove‐edged graphene nanoribbons where helical twisting of the graphene nanoribbon backbone is tuned through functionalization with chiral side chains.S‐configured point chiral centers in the side chains transfer their chiral information to induce a helically chiral, right‐handed twist in the graphene nanoribbon. As the backbone is extended, these helically twisted graphene nanoribbons exhibit a substantial increase in their circular dichroic response. The longest variant synthesized consists of an average of 268 linearly fused rings, reaching 65 nm in average length with nearly 10 full end‐to‐end helical rotations. The structure exhibits an extraordinary |Δε| value of 6780 M⁻¹cm⁻¹at 550 nm—the highest recorded for an organic molecule in the visible wavelength range. This new chiroptic material acts as room‐temperature spin filters in thin films due to its chirality‐induced spin selectivity. 

Recent years have seen tremendous progress towards understanding the relation between the molecular structure and function of organic field effect transistors. The metrics for organic field effect transistors, which are characterized by mobility and the on/off ratio, are known to be enhanced when the intermolecular interaction is strong and the intramolecular reorganization energy is low. While these requirements are adequate when describing organic field effect transistors with simple and planar aromatic molecular components, they are insufficient for complex building blocks, which have the potential to localize a carrier on the molecule. Here, we show that intramolecular conductivity can play a role in controlling device characteristics of organic field effect transistors made with macrocycle building blocks. We use two isomeric macrocyclic semiconductors that consist of perylene diimides linked with bithiophenes and find that the trans -linked macrocycle has a higher mobility than the cis -based device. Through a combination of single molecule junction conductance measurements of the components of the macrocycles, control experiments with acyclic counterparts to the macrocycles, and analyses of each of the materials using spectroscopy, electrochemistry, and density functional theory, we attribute the difference in electron mobility of the OFETs created with the two isomers to the difference in intramolecular conductivity of the two macrocycles.