A Cost-Effective Way to Produce Gram-Scale ¹⁸O‑Labeled Aromatic Aldehydes

Obtaining 18O-labeled organic substances is of great research importance and also an extremely challenging work. In this work, depending on the reversed Knoevenagel reaction, 18O-labeled aromatic aldehydes (3a–3x) are successfully obtained with high total yields (52–72%) and sufficient 18O abundance (90.90–96.09%)

Simple Way to Fabricate Emissive Boron-Containing Covalent Organic Frameworks

Highly fluorescent covalent organic frameworks (COFs) are rarely obtained because of the π–π stacked layers with aggregation-caused quenching behavior. Unarguably, highly fluorescent COFs with tunable emission colors are even more rarely achieved. Herein, a general strategy to modify the classical COF material (named COF-1) by different fluorescent molecules via N → B interaction was developed. In this method, the boron-containing COF-1 acted as a porous and crystalline matrix as well as a reaction partner of Lewis acid; after interacting with fluorescent molecules with the anchoring group of pyridine (Lewis base), COF-1 takes a gorgeous transfiguration from a non-emissive powder into a highly fluorescent COF material with tunable emission colors. This disclosed method endowed the typical COFs with new emissive life and is speculated with the general research concept for all boron-containing COFs. Benefiting from the prominent fluorescent emission in the aggregation state, sensitive probes toward amines are achieved