Does Ozone–Water Complex Produce Additional OH Radicals in the Atmosphere?

Ozone–water complex has been thought to play a role in producing atmospheric OH radicals through its photolysis. Here, we re-examined the absorption cross-section of the ozone–water complex with a new method to tell whether the above speculation is valid. With argon solvation and photoionization by tunable vacuum ultraviolet light, we were able to selectively probe the ozone–water 1:1 complex. The measured cross-section of the complex is only similar to the sum of the cross-sections of ozone and water monomers at 157.6, 248.4, and 308.4 nm. In addition, we did not observe any absorption of the complex at 351.8 nm. The results indicate that the OH production through the photolysis of the ozone–water complex is much slower than previously thought

Dicyanomethylene-Functionalized Squaraine as a Highly Selective Probe for Parallel G‑Quadruplexes

DNA sequences that can form G-quadruplexes (G4s) are highly prevalent in the genome. However, the structures and functions of most G4-forming sequences in the genome are poorly understood. Therefore, the development of molecular probes for G4 recognition in biological samples, especially probes with long wavelength, are important for the basic research of G4s. Squaraines dyes exhibit sharp and intense absorption and strong emission in the red to NIR region, but very few of them have been reported as probes for the recognition of nucleic acids. Here we report the interactions of two squaraine dyes, STS and CSTS, with different kinds of DNA. The dicyanomethylene-functionalized squaraine dye, CSTS, exhibits strong interaction with the parallel G4s, but no interaction with other DNA. In aqueous conditions, this interaction causes the transformation of CSTS from H-aggregates to monomers, which results in decline and growth of the absorption spectra of both forms. The parallel G4s enhance the fluorescence of both STS and CSTS, but the fluorescence enhancement of CSTS is much higher than that of STS. CSTS is demonstrated to bind to G4s through end-stacking model on G-quartet surface. The high selectivity of CSTS to parallel G4s is attributed to its V-shaped rigid planar π scaffold. The high selectivity, very low background fluorescence, large absorption coefficient, and high fluorescence quantum yield make CSTS hold great promise as a long-wavelength probe for parallel G4 detection in biological samples or in vivo

Double-Carbon Matrix-Supported MnO₂ for High-Voltage Supercapacitors in a Neutral Aqueous System

The low conductivity and poor structural stability of MnO2 nanoparticles have impeded further enhancement in specific energy density for aqueous asymmetric supercapacitors. To address this issue, in this article, carbon nanotubes (CNTs) and mesoporous carbon (meso-C) are merged together, ultrasonically treated with poly(sodium 4-styrenesulfonate) surfactant and then immersed in a KMnO4 solution at room temperature to generate a composite, namely, double-carbon matrix (CNTs and meso-C)-supported K–MnO2 (K+ incorporated state). When this composite was employed as an electrode in the neutral aqueous electrolyte, this material behaved as a redox pseudocapacitor and delivered a maximum specific capacity of 292.5 C g–1 (∼585 F g–1). When the composite was used as one electrode and the negative-activated carbon was employed as the other electrode, the as-assembled hybrid asymmetric device in the neutral aqueous system could achieve a specific capacitance of 86.0 F g–1 within an ultrahigh potential range of 0–2.1 V, breaking through a bondage of 2.0 V. This energy-storage device could deliver 52.7 W h kg–1, correlating to a power density of 525 W kg–1. Moreover, the effects of various ratios between CNTs and meso-C on the resulting performance were also investigated and compared