Modulating vectored non-covalent interactions for layered assembly with engineerable properties

Vectored non-covalent interactions—mainly hydrogen bonding and aromatic interactions—extensively contribute to(bio)-organic self-assembling processes and significantly impact the physicochemical properties of the associated superstructures.However,vectored non-covalent interaction-driven assembly occursmainly along one-dimensional(1D)or three-dimensional(3D)directions,and a two-dimensional(2D)orientation,especially that of multilayered,graphene-like assembly,has been reported less.In this present research,by introducing amino,hydroxyl,and phenyl moieties to the triazine skeleton,supramolecular layered assembly is achieved by vectored non-covalent interactions.The planar hydrogen bonding network results in high stability,with a thermal sustainability of up to about 330°C and a Young’s modulus of up to about 40 GPa.Upon introducing wrinkles by biased hydrogen bonding or aromatic interactions to disturb the planar organization,the stability attenuates.However,the intertwined aromatic interactions prompt a red edge excitation shift effect inside the assemblies,inducing broad-spectrum fluorescence covering nearly the entire visible light region(400–650 nm).We show that bionic,superhydrophobic,pillar-like arrays with contact angles of up to about 170°can be engineered by aromatic interactions using a physical vapor deposition approach,which cannot be realized through hydrogen bonding.Our findings show the feasibility of 2D assembly with engineerable properties by modulating vectored non-covalent interactions.

Getting the Lead Out:Biomolecular Crystals as Low-Cost,High-Performance Piezoelectric Components

INTRODUCTION There are billions of piezoelectric sensors globally in our vehicles,consumer electronics,medical devices,advanced scientific equipment,fuel gauges,and structural health monitoring units.The vast majority of these sensors contain the perovskite lead zirconium titanate(PZT).It is estimated that there is 100 g of PZT distributed across a variety of integrated sensors in every one of the 1.4 billion cars on our roads.PZT requires toxic lead oxide(PbO)during its synthesis and leaches lead into water supplies at end-of-life disposal.Lead-free alternatives are a large field of research,yet the most-touted candidates,which are also ceramic materials containing elements such as niobium,bismuth,and barium,are even more damaging to the environment(Figure 1).