Superamphiphilic Silicon Wafer Surfaces and Applications for Uniform Polymer Film Fabrication

Silicon wafers have been widely used in the semiconductor industry for many decades. Over the past decades, with the development of organic optoelectronic materials, silicon-based organic–inorganic hybrid devices have received more and more interest in fundamental and applied research. To obtain uniform organic films for hybrid devices, superamphiphilic surfaces, on which both water and oil can spread completely, show great advantages. Herein, we prepared superamphiphilic silicon wafer surfaces with contact angles (CAs) near 0° for both water and typical organic liquids. Interestingly, lateral force mode (LFM) atomic force microscopy (AFM) images indicate that the superamphiphilicity is induced by alternating hydrophilic and hydrophobic nanodomains. By making use of these superamphiphilic silicon wafer surfaces, uniform polypyrrole (PPy) films were generated in both water and cyclopentanone, providing a versatile and effective way for the integration of organic optoelectronic materials with inorganic microelectronic devices.     

Rapid Chemical Reaction Monitoring by Digital Microfluidics‐NMR: Proof of Principle Towards an Automated Synthetic Discovery Platform

Microcoil nuclear magnetic resonance (NMR) has been interfaced with digital microfluidics (DMF) and is applied to monitor organic reactions in organic solvents as a proof of concept. DMF permits droplets to be moved and mixed inside the NMR spectrometer to initiate reactions while using sub‐microliter volumes of reagent, opening up the potential to follow the reactions of scarce or expensive reagents. By setting up the spectrometer shims on a reagent droplet, data acquisition can be started immediately upon droplet mixing and is only limited by the rate at which NMR data can be collected, allowing the monitoring of fast reactions. Here we report a cyclohexene carbonate hydrolysis in dimethylformamide and a Knoevenagel condensation in methanol/water. This is to our knowledge the first time rapid organic reactions in organic solvents have been monitored by high field DMF‐NMR. The study represents a key first step towards larger DMF‐NMR arrays that could in future serve as discovery platforms, where computer controlled DMF automates mixing/titration of chemical libraries and NMR is used to study the structures formed and kinetics in real time.     

Exploring a Route to Cyclic Acenes by On‐Surface Synthesis

A route to generate cyclacenes by on‐surface synthesis is explored. We started by synthesizing two tetraepoxycyclacenes by sequences of Diels–Alder cycloadditions. Subsequently, these molecules were deposited onto Cu(111) and scanning‐tunneling‐microscopy(STM)‐based atom manipulation was employed to dissociate the oxygen atoms. Atomic force microscopy (AFM) with CO‐functionalized tips enabled the detailed characterization of the reaction products and revealed that, at most, two oxygens per molecule could be removed. Importantly, our experimental results suggest that the generation of cyclacenes by the described route might be possible for larger epoxycyclacenes.     

Single‐Molecule Visualization of the Activity of a Zn2+‐Dependent DNAzyme

We demonstrate the single‐molecule imaging of the catalytic reaction of a Zn²⁺‐dependent DNAzyme in a DNA origami nanostructure. The single‐molecule catalytic activity of the DNAzyme was examined in the designed nanostructure, a DNA frame. The DNAzyme and a substrate strand attached to two supported dsDNA molecules were assembled in the DNA frame in two different configurations. The reaction was monitored by observing the configurational changes of the incorporated DNA strands in the DNA frame. This configurational changes were clearly observed in accordance with the progress of the reaction. The separation processes of the dsDNA molecules, as induced by the cleavage by the DNAzyme, were directly visualized by high‐speed atomic force microscopy (AFM). This nanostructure‐based AFM imaging technique is suitable for the monitoring of various chemical and biochemical catalytic reactions at the single‐molecule level.