A novel triptycene-based azo polymer (TBAP) was explored as a switching material in an atomic switch showing resistive change under voltage sweep and pulse. Current atomic force microscope (C-AFM) measurements...

Understanding and control of molecular alignment at the nanoscale in self-assembled supramolecular structures is a prerequisite for the subsequent exploitation of molecules in functional devices. Here, we have clarified the...

Beyond explaining scientific curiosity, molecular self-assembly is an essential tool for the controlled fabrication of nanoscale devices with the desired functionalities. Molecules containing azo groups are potential candidates for photoswitchable optoelectronic applications. Herein, we synthesized an alkylated azobenzene (AAB) molecule and studied its interfacial selfassembly by surface manometry and molecular dynamics (MD) simulation. The alkylated azobenzene molecules form a stable and reversible monolayer at the air−water interface. The monolayer phase transforms from a liquid expanded (LE) to liquid condensed (LC) phase upon compression, as observed by surface pressure (π)−area per molecule (A) and surface potential (ΔV)−A isotherms and Brewster angle microscopy (BAM). Using MD simulation, the resultant molecular ordering is analyzed via orientational structural profiles, spatial and radial distributions, order parameters, and densmap profiles. Not only the simulated isotherm corroborated the experimental observations, but the MD simulation also revealed that the number of hydrogen bonds in the molecule−molecule interaction dominates over the molecule− water interaction in the LC phase. However, a perfectly ordered alignment of tail groups is not seen due to the hindrance between the head groups featured by the diazo benzene group. This study elucidates the molecular interactions controlling the self-assembly responsible for forming a stable monolayer at the air−water interface.

With excellent charge carrier mobility, tendency to form long-range assembly with self-healing ability, and remarkable chemical and mechanical stability, highly conjugated discotic molecules constitute an important class of materials for electronic applications. Here, we report formation of the stable free-standing molecular film of heterocoronene-based discotic liquid crystal (DLC) molecules, held solely by supra-molecular non-covalent interactions. The films of monolayer thickness (∼4 nm) were lifted from Langmuir trough directly onto a circular ring of diameter up to 2 mm as well as onto TEM grids. Films remain free-standing up to a macroscopic length scale, as revealed by optical and secondary electron microscopy, presumably due to the synergistic effect of intermolecular π−π interactions and the dispersion forces between the peripheral alkyl chains as well as their interdigitation. The monolayer is more than 97% transparent in the visible range. Further, resistive switching measurements carried out on the monolayer DLC film transferred on a silver substrate revealed electrochemical metallization to be the governing process. The switching time was found to decrease exponentially with voltage indicating nucleation to be a possible rate-limiting step. We anticipate that the method presented here will facilitate utilization of such non-covalent freestanding films in flexible memristor and nano-electromechanical systems.