Coordination compounds of copper, nickel and iron with Schiff bases derived from hydroxynaphthaldehydes and salicylaldehydes

Bromate formation in ozone-based advanced oxidation processes (AOPs) was investigated by laboratory experiments in combination with kinetic modeling. Oxidant concentrations were monitored during the experiments, which allows us to account for the relative contributions of ozone and OH radical pathways. It has been shown by gamma-irradiation of bromide-containing solutions in the pH range 6-8 that bromate can be formed by a pure OH radical mechanism and that hypobromous acid/hypobromite (HOBr/ OBr-) is a requisite intermediate in bromate formation. The presence of hydrogen peroxide (H2O2), as in H2O2-based AOPs, leads to a reduction of HOBr/OBr- and therefore becomes a key reaction for the control of bromate formation. The steady-state concentration of OH radicals in AOPs is usually not high enough to compensate for this reduction reaction. Therefore, in gamma-irradiation experiments, no bromate was formed in the presence of H2O2 because OH radicals were the only possible oxidants to further oxidize HOBr/OBr-. However, in ozone-based AOPs at pH 7, where ozone is present in combination with H2O2, bromate was still formed. This was attributed to the oxidation of Br-. by O-3, which was investigated at pH 7. Our experimental findings could be best explained by a corresponding second-order rate constant k = 1.5 x 10(8) M-1 s(-1).

Advanced Oxidation of Bromide-Containing Waters: Bromate Formation Mechanisms

Intramolecular hydrogen bonding and tautomerism in Schiff bases. Structure of N-(2-pyridil)-2-oxo-1-naphthylidenemethylamine

Traditionally, the properties and functions of covalent organic frameworks (COFs) are defined by their constituting building blocks, while the chemical bonds that connect the individual subunits have not attracted much attention as functional components of the final material. We have developed a new series of dual-pore perylene-based COFs and demonstrated that their imine bonds can be protonated reversibly, causing significant protonation-induced color shifts toward the near-infrared, while the structure and crystallinity of the frameworks are fully retained. Thin films of these COFs are highly sensitive colorimetric acid vapor sensors with a detection limit as low as 35 μg L-1 and a response range of at least 4 orders of magnitude. Since the acidochromism in our COFs is a cooperative phenomenon based on electronically coupled imines, the COFs can be used to determine simultaneously the concentration and protonation strength of nonaqueous acid solutions, in which pH electrodes are not applicable, and to distinguish between different acids. Including the imine bonds as function-determining constituents of the framework provides an additional handle for constructing multifunctional COFs and extending the range of their possible applications.

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Perylene-Based Covalent Organic Frameworks for Acid Vapor Sensing.

John W. Ledbetter

Papers

Infrared spectra of N-aryl imines of o-hydroxybenzaldehyde between 2000 and 1500 cm-1

Spectroscopic Evidence for the Enol Imine-Keto Enamine Tautomerism of N-(o- and p-Hydroxybenzylidene) Anils in Solution

Substituent effects on the tautomerism of Schiff bases

Resonance Raman spectra of the tautomers of pyridoxal and salicylaldehyde Schiff bases

Tautomerism of N-(o-hydroxybenzylidene) anils in nonacidic solvents