Improving performance of single-pass real-time holographic projection

© 2019 Elsevier B.V. This work describes a novel approach to time-multiplexed holographic projection on binary phase devices. Unlike other time-multiplexed algorithms where each frame is the inverse transform of independently modified target images, Single-Transform Time-Multiplexed (STTM) hologram generation produces multiple sub-frames from a single inverse transform. Uniformly spacing complex rotations on the diffraction field then allows the emulation of devices containing 2N modulation levels on binary devices by using N sub-frames. In comparison to One-Step Phase Retrieval (OSPR), STTM produces lower mean squared error for up to N=5 than the equivalent number of OSPR sub-frames with a generation time of [Formula presented] of the equivalent OSPR frame. A mathematical justification of the STTM approach is presented and a hybrid approach is introduced allowing STTM to be used in conjunction with OSPR in order to combine performance benefits.Engineering and Physical Sciences Research Council (EP/L016567/1 and EP/L015455/1

Photomodulation of fluoride ion binding through anion-pi interactions using a photoswitchable azobenzene system

The discovery of photoswitchable azobenzene-systems that undergo trans-to-cis photoisomerisation was a milestone in supramolecular chemistry. Such photoswitches have possible applications in data storage, stimuli responsive delivery systems, and molecular machines due to fast and selective switching. However, the light induced cis isomer of azobenzene is rather unstable and reverts thermally and photochemically to the thermodynamically stable trans configuration. We report, for the first time, controlled photoswitching of an azo-naphthalenediimide (azo-NDI) which can be achieved upon binding of fluoride ions through anion-φ interaction. This NDI-F-NDI "sandwich' stabilises the cis configuration through the generation of an NDI-radical anion, and a dianionic, NDI 2- species that becomes unusually stable in the cis form. The sandwiched cis form reverts to the trans form only upon de complexation of F -. A model pollutant was successfully degraded using the photogenerated NDI-F-NDI sandwich. This opens a wide range of applications in molecular and supramolecular nanotechnology

Construction of Donor–Acceptor Polymers via Cyclopentannulation of Poly(arylene ethynylene)s

A one-step postpolymerization modification that converts three high bandgap poly­(arylene ethynylene)­s into low bandgap donor–acceptor copolymers is described. The strategy relies on a palladium-catalyzed cyclopentannulation reaction between the main-chain ethynylene functionality and a small molecule aryl bromide (6-bromo-1,2-dimethylaceanthrylene). The reaction installs new cyclopenta­[<i>hi</i>]­aceanthrylene electron-accepting groups between the electron rich arylenes along the polymer backbone. The modified polymers include poly­(9,9-didodecyl-fluorene-2,7-ethynylene), poly­(9-dodecyl-carbazole-2,7-ethynylene), and poly­(2,5-dioctyloxyphenylene-1,4-ethynylene). The functionalization efficiency was evaluated via isotopic ¹³C labeling of the polymeric ethynylene carbons and then monitoring the chemical environment of those carbons via NMR spectroscopy. Near complete conversion of the sp carbon species to sp² carbon species was observed, which demonstrates the high efficiency of the modification strategy. Gel permeation chromatography shows that the hydrodynamic radius of the polymers is reduced considerably going from linear to kinked polymer morphology upon functionalization, and molecular dynamics simulations illustrate the underlying morphological change. The newly formed donor–acceptor polymers showed dramatically different optical and electrochemical properties from the precursor poly­(arylene ethynylene) polymers. A new absorption band centered at ∼650 nm represents a red-shift of >300 nm for the onset of absorption compared with that of precursor polymers and cyclic voltammetry shows two new low-lying reduction peaks that coincide with the cyclopenta­[<i>hi</i>]­aceanthrylene moiety