Switchable π-electronic network of bis(α-oligothienyl)-substituted hexaphyrins between helical versus rectangular circuit

The switching phenomena of conformation with π-electronic network through deprotonation-protonation processes were investigated by employing a series of 5, 20-bis(α-oligothienyl) substituted hexaphyrins(1.1.1.1.1.1). They showed significant changes in the absorption and emission spectra with deprotonation, and returned to the initial state with protonation. Through NMR measurements and single crystal X-ray diffraction analysis, we found that the 5, 20-bis(α-oligothienyl) substituted hexaphyrins, which possess acyclic, helical electronic networks involving oligothienyl chains in dumbbell conformations (type-I) in a neutral form, underwent effective deprotonation upon treatment with tetrabutylammonium fluoride (TBAF) to generate the corresponding dianions, which display cyclic electronic networks with enhanced aromaticity in rectangular conformations (type-II). Our quantum calculation results provide an unambiguous description for the switchable conformation and π-conjugation, which revealed that a deprotonation-induced enhanced aromatic conjugation pathway is involved in the switchable π-electronic network

Dark to light! A new strategy for large Stokes shift dyes: coupling of dark donor with tunable high quantum yield acceptors

10.1039/c4sc01821dChemical Science5124812-481

Air-stable van der Waals PtTe2 conductors with high current-carrying capacity and strong spin- orbit interaction

High-performance van der Waals (vdW) integrated electronics and spintronics require reliable current-carrying capacity. However, it is challenging to achieve high current density and air-stable performance using vdW metals owing to the fast electrical breakdown triggered by defects or oxidation. Here, we report that spin-orbit interacted synthetic PtTe2 layers exhibit significant electrical reliability and robustness in ambient air. The 4-nm-thick PtTe2 synthesized at a low temperature (similar to 400 degrees C) shows intrinsic metallic transport behavior and a weak antilocalization effect attributed to the strong spin-orbit scattering. Remarkably, PtTe2 sustains a high current density approaching approximate to 31.5 MA cm(-2), which is the highest value among electrical interconnect candidates under oxygen exposure. Electrical failure is caused by the Joule heating of PtTe2 rather than defect-induced electromigration, which was achievable by the native TeOx passivation. The high-quality growth of PtTe2 and the investigation of its transport behaviors lay out essential foundations for the development of emerging vdW spin-orbitronics

Three-dimensional aromaticity in an antiaromatic cyclophane

Understanding of interactions among molecules is essential to elucidate the binding of pharmaceuticals on receptors, the mechanism of protein folding and self-assembling of organic molecules. While interactions between two aromatic molecules have been examined extensively, little is known about the interactions between two antiaromatic molecules. Theoretical investigations have predicted that antiaromatic molecules should be stabilized when they stack with each other by attractive intermolecular interactions. Here, we report the synthesis of a cyclophane, in which two antiaromatic porphyrin moieties adopt a stacked face-to-face geometry with a distance shorter than the sum of the van der Waals radii of the atoms involved. The aromaticity in this cyclophane has been examined experimentally and theoretically. This cyclophane exhibits three-dimensional spatial current channels between the two subunits, which corroborates the existence of attractive interactions between two antiaromatic π-systems

Opportunities and challenges in sustainable treatment and resource reuse of sewage sludge: A review

Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge. Recovery of enzymes, bio-plastics, bio-pesticides, proteins and phosphorus are discussed as a means to visualize sludge as a potential opportunity instead of a nuisance

Synthesis of Chlorine or Zinc Incorporated Indium Phosphide Magic Sized Cluster Families and Their Series of Multi-step Conversions

InP magic sized clusters (MSCs) have attracted great interest to better understand the underlying mechanisms of InP quantum dot (QD) synthesis. InP MSCs that host heterogeneous atoms have not been properly studied so far. We report two families of InP MSCs that incorporate chlorine atoms (InP:Cl) or zinc atoms (InP:Zn). Methods to synthesize two InP:Cl MSCs (F360-InP:Cl MSCs; F399-InP:Cl MSCs) and three InP:Zn MSCs (F360-InP:Zn MSCs; F408-InP:Zn MSCs; F393-InP:Zn MSCs) were developed to obtain each directly from molecular precursors. Alternatively, each series of MSCs could be prepared by sequential conversions (Scheme 1). 386-InP MSCs ([In37P20](O2CR)51, R=alkyl) could be converted to F360-InP:Cl MSCs, then to F399-InP:Cl MSCs. Analogously, F360-InP:Zn MSCs could be converted to F408-InP:Zn MSCs, then to F393-InP:Zn MSCs. XRD, Raman, FT-IR, XPS, and NMR spectroscopies were performed to characterize the MSCs. Time-resolved spectroscopies revealed that 386-InP MSCs and F360-InP:Cl MSCs similarly behave like small molecules whereas F399-InP:Cl MSCs have QD-like characters. F360-InP:Zn MSCs was quite distinct from F408-InP:Zn MSCs and F393-InP:Zn MSCs, where the latter two MSCs shared the same inorganic skeleton and exhibited more QD-like characteristics. Studies on MSCs as QD intermediates can reveal unprecedented ways to rationally design nanostructures beyond conventional syntheses.1