Direct Synthesis of Amide-Linked COFs via Ester-Amine Exchange Reaction.

Achieving both crystallinity and stability is challenging for covalent organic frameworks (COFs) as the reversible reaction required for enhancing crystallinity compromises stability. Amide linkages, a type of chemically stable bond for COF construction, are predominantly synthesized via postmodifications. This work presents a direct and convenient method for synthesizing highly crystalline amide-linked COFs via the ester-amine exchange reaction.

Constrution of Quinazoline-Linked Covalent Organic Frameworks via a Multicomponent Reaction for Photocatalysis.

Quinazoline (Qz)-linked covalent organic frameworks (COFs) have been constructed via a three-component reaction of ortho-acylanilines, benzaldehydes and NHOAc. The structure of Qz-COFs has been confirmed by solid-state nuclear magnetic resonance spectroscopy, Fourier transform infrared and powder X-ray diffraction patterns. The Qz-COFs possess high chemical stability, showing good endurance to strong acid, strong base, oxidant, reductant and other conditions.

Comparison of the Revised Air Quality Index with the PSI and AQI indices.

Air pollution indices are commonly used to indicate the level of severity of air pollution to the public. The Pollution Standards Index (PSI) was initially established in response to a dramatic increase in the number of people suffering respiratory irritation due to the deteriorating air quality. The PSI was subsequently revised and implemented by the USEPA in 1999, and became known as the Air Quality Index (AQI) that includes data relating to particle suspension, PM2.