Absorbate-Induced Piezochromism in a Porous Molecular Crystal

Atmospherically stable porous frameworks and materials are interesting for heterogeneous solid–gas applications. One motivation is the direct and selective uptake of pollutant/hazardous gases, where the material produces a measurable response in the presence of the analyte. In this report, we present a combined experimental and theoretical rationalization for the piezochromic response of a robust and porous molecular crystal built from an extensively fluorinated trispyrazole. The electronic response of the material is directly determined by analyte uptake, which provokes a subtle lattice contraction and an observable bathochromic shift in the optical absorption onset. Selectivity for fluorinated absorbates is demonstrated, and toluene is also found to crystallize within the pore. Furthermore, we demonstrate the application of electronic structure calculations to predict a physicochemical response, providing the foundations for the design of electronically tunable porous solids with the chemical properties required for development of novel gas-uptake media

C-60/Na4FeO3/Li3V2(PO4)(3)/soft carbon quaternary hybrid superstructure for high-performance battery-supercapacitor hybrid devices

To develop battery-supercapacitor hybrid devices with high energy and power densities, we propose a rational design of a quaternary hybrid superstructure by using a high-energy biotemplate. This new superstructure is composed of stable fullerene C-60 nanocages, electroactive Na4FeO3, high-energy Li3V2(PO4)(3) and soft carbon as well as tubular ordered mesoporous channels. This design takes advantage of the unique properties of each component, resulting in nanocomposites with synergistic effects to improve the charge transfer and energy storage. We found that this quaternary hybrid electrode has both high energy and power densities as well as a long cycling life in a Li/Na mixed-ion electrolyte, outperforming a multitude of other battery-supercapacitor hybrid devices reported thus far. The charge storage mechanisms of this hybrid superstructure are proposed for optimizing the electrode design

The Use of a Vanadium Species as a Catalyst in Photoinduced Water Oxidation

The first water oxidation catalyst containing only vanadium atoms as metal centers is reported. The compound is the mixed-valence [(VIV 5VV 1)O7(OCH3)12]− species, 1. Photoinduced water oxidation catalyzed by 1, in the presence of Ru(bpy)3 2+ (bpy = 2,2′-bipyridine) and Na2S2O8, in acetonitrile/aqueous phosphate buffer takes place with a quantum yield of 0.20. A hole scavenging reaction between the photochemically generated Ru- (bpy)3 3+ and 1 occurs with a bimolecular rate constant of 2.5 × 108 M−1 s−1. The time-resolved formation of the oxidized molecular catalyst 1+ in bimolecular reactions is also evidenced for the first time by transient absorption spectroscopy. This result opens the way to the use of less expensive vanadium clusters as water oxidation catalysts in artificial photosynthesis schemes