Fe(III)-Activated Sulfite Revisited: The Overlooked Role of High-Valent Iron(IV)-Oxo Complex (Fe(IV)) in Water Treatment

Sulfate radical (SO4•−) and its secondary radical (hydroxyl radical, •OH) are commonly recognized as the primary reactive intermediates formed by Fe(III)/sulfite system. However, it still remains unknown whether Fe(IV) is involved in this system where the well documented Fe(IV)-precursors (i.e., Fe(II) and persulfates) were in-situ generated. Intriguingly, we observed that methyl phenyl sulfone (PMSO2), indicative of Fe(IV) formation, was formed during methyl phenyl sulfoxide (PMSO) transformation in Fe(III)/sulfite system, which unprecedently verified that Fe(IV) played a crucial role in it. In parallel, the involvement of SO4•− and •OH in this system were also identified, but the limited •OH was proposed to be derived from hydrolysis of both Fe(IV) and SO4•−, rather than by self-decay of SO4•− alone. Moreover, the contribution of Fe(IV) relative to it of free radicals was explored by monitoring the yield of PMSO2. It was disclosed that the relative contribution of Fe(IV) was progressively promoted as Fe(III)-sulfite reaction proceeding with an upper limit of 80%-90%, and it was accelerated by promoting Fe(III) and sulfite dosages, while was declined with increasing pH. Furthermore, a kinetic model was developed, which precisely simulated kinetic traces of PMSO transformation and dissolved oxygen evolution in Fe(III)/sulfite system. More importantly, the kinetic model offered the first insight into the evolution of Fe(IV), SO4•−, and •OH, which provided in-depth mechanistic understanding of the iron-catalyzed sulfite auto-oxidation process. Considering the different chemical properties between Fe(IV) and free radicals, it is urgent to re-evaluate the decontamination process by iron/sulfite system.

The Effect of Molecular Aggregation of Thermally Activated Delayed Fluorescence Sensitizer for Hyperfluorescence in Organic Light-Emitting Diodes

The exciton behavior of a new synthetic material, 11-phenyl-11H-9,16-dioxa-11-aza-4b-boraindeno[1,2-a]naphtho[3,2,1-de] anthracene (Ph-OBNA), which displays a multi-resonance effect, and bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) with a donor–acceptor-donor structure was analyzed. First, we conducted quantum mechanical...

Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (BR) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The BR values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

Asymmetric synthesis of CF2-functionalized aziridines by combined strong Brønsted acid catalysis

A diastereo- and enantioselective approach to access chiral CF2-functionalized aziridines from difluorodiazoethyl phenyl sulfone (PhSO2CF2CHN2) and in situ-formed aldimines is described. This multicomponent reaction is enabled by a combined strong Brønsted acid catalytic platform consisting of a chiral disulfonimide and 2-carboxyphenylboronic acid. The optical purity of the obtained CF2-substituted aziridines could be further improved by a practical dissolution–filtration procedure.