Induction, transmission, and manipulation of chirality in molecular systems are well known, widely applied concepts. However, our understanding of how chirality of nanoscale entities can be controlled, measured, and transmitted to the environment is considerably lacking behind. Future discoveries of dynamic assemblies engineered from chiral nanomaterials, with a specific focus on shape and size effects, require exact methods to assess transmission and amplification of nanoscale chirality through space. Here we present a remarkably powerful chirality amplification approach by desymmetrization of plasmonic nanoparticles to nanorods. When bound to gold nanorods, a one order of magnitude lower number of chiral molecules induces a tighter helical distortion in the surrounding liquid crystal–a remarkable amplification of chirality through space. The change in helical distortion is consistent with a quantification of the change in overall chirality of the chiral ligand decorated nanomaterials differing in shape and size as calculated from a suitable pseudoscalar chirality indicator.

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Understanding and controlling the growth of organic crystals deposited from the vapor phase is important for fundamental materials science and necessary for applications in pharmaceutical and organic electronics industries. Here, this process is studied for the paradigmatic case of pentacene on silica by means of a specifically tailored computational approach inspired by the experimental vapor deposition process. This scheme is able to reproduce the early stages of the thin-film formation, characterized by a quasi layer-by-layer growth, thus showcasing its potential as a tool complementary to experimental techniques for investigating organic crystals. Crystalline islands of standing molecules are formed at a critical coverage, as a result of a collective reorientation of disordered aggregates of flat-lying molecules. The growth then proceeds by sequential attachment of molecules at the cluster and then terrace edges. Free-energy calculations allowed us to characterize the step-edge barrier for descending the terraces, a fundamental parameter for growth models for which only indirect experimental measurements are available. The barrier is found to be layer-dependent (approximately 1 kcal/mol for the first monolayer on silica, 2 kcal/mol for the second monolayer) and to extend over a distance comparable with the molecular length.

We have studied chiral induction in a nematic in contact with a chiral surface using computer simulations. Nematic and surface particles have been modelled using the GayÈBerne (GB) potential considering, additionally, a short-range chiral term for the inducing surface. We Ðnd that, close to the chiral surface, a twist of the local director with respect to the surface molecules is induced, even in the isotropic phase. In the nematic phase, the twist is maintained through orientational correlation and, even well inside, the sample molecules are e †ectively twisted with respect to the surface director. This process can highlight the basic mechanism of the chiral induction of a cholesteric, i.e. chiral nematic, phase. A detailed description of the molecular organization at various distances from the inducing surface is presented, using scalar and pseudoscalar orientational correlation functions.A well known but still fascinating e †ect is the induction of a chiral nematic phase upon dissolving a small quantity of a chiral solute in a nematic,1,2 which can exhibit a huge susceptivity to this chiral perturbation. Such induced chiral nematic phases have a helical structure with a repeat distance that can be of a length comparable to the wavelength of visible or IR light, depending on soluteÈsolvent characteristics and solute concentration. The induction of a macroscopic twist seems likely to be connected to the extent of orientational pair correlation. In fact, the induced optical activity, which is a measurable quantity related to chirality, is very weak in the isotropic phase compared to that measurable in nematic phases.3,4 Since the concentration of chiral dopants needed to induce a cholesteric phase can be very low, even mole fractions of the chiral inducer below 10~4 are sufficient,5 it is difficult to understand how the local director twist is generated and propagated. Indeed, every chiral molecule is expected to have an environment with a large predominance of achiral molecules and yet the chiral induction is very e †ective. This is further complicated by the fact that chiral interactions are expected to be, on one hand, weak and, on the other, fairly shortranged.6,7 The induction of a chiral nematic phase has been extensively studied, both experimentally and theoretically (see e.g. ref. 8 and references therein). However, we are aware of no detailed computer simulation study of systems of chiral molecules dissolved in a nematic phase. Such a study would, in any case, be very complicated, using computer simulations, particularly since the low concentrations involved would make it very difficult to calculate meaningful statistics.We have thus decided to study by computer simulation the chiral induction in a simpler and more controlled system, where a nematic is put in contact with a surface covered by chiral molecules which cannot di †use into the nematic bulk. Such systems could be prepared by coating the surface in contact with the nematic with a layer of chiral molecules or with a chiral polymer.In this work ...

We present a computational approach to model hole transport in an amorphous semiconducting fluorene-triphenylamine copolymer (TFB), which is based on the combination of molecular dynamics to predict the morphology of the oligomeric system and Kinetic Monte Carlo (KMC), parameterized with quantum chemistry calculations, to simulate hole transport. Carrying out a systematic comparison with available experimental results, we discuss the role that different transport parameters play in the KMC simulation and in particular the dynamic nature of positional and energetic disorder on the temperature and electric field dependence of charge mobility. It emerges that a semi-quantitative agreement with experiments is found only when the dynamic nature of the disorder is taken into account. This study establishes a clear link between microscopic quantities and macroscopic hole mobility for TFB and provides substantial evidence of the importance of incorporating fluctuations, at the molecular level, to obtain results that are in good agreement with temperature and electric field-dependent experimental mobilities. Our work makes a step forward towards the application of nanoscale theoretical schemes as a tool for predictive material screening.