Nonclassical Crystallization Processes of Single-Crystalline Two-Dimensional Covalent Organic Frameworks.

Controlling the two-dimensional polymerization processes of two-dimensional covalent organic frameworks (2D COFs) is essential to fully realizing their distinct properties. Although most 2D COFs have been isolated as polycrystalline aggregates with only nanometer-scale crystalline domains, we have identified rapid, solvothermal conditions that provide micrometer-scale and larger single-crystal 2D polymers for a few 2D COFs. Yet it remains unclear why certain conditions produce far larger 2D polymers than others, which hinders generalizing these findings.

Nitrous oxide as a diazo transfer reagent: the synthesis of triazolopyridines.

Nitrous oxide is a potential diazo transfer reagent, but its applications in organic chemistry are scarce. Here, we show that triazolopyridines and triazoloquinolines are formed in the reactions of metallated 2-alkylpyridines or 2-alkylquinolines with NO. The reactions can be performed under mild conditions and give synthetically interesting triazoles in moderate to good yields.

Brønsted and Lewis acid adducts of triazenes.

The synthetic utility of triazenes rests on the fact that the triazene function can be cleaved by Brønsted or Lewis acids, liberating diazonium compounds. However, the preferred coordination site of the acid is still a matter of debate. We have analyzed triflic acid, B(CF), and PdCl adducts of triazenes by NMR spectroscopy and single crystal X-ray crystallography.

Synthesis and Properties of 1-Acyl Triazenes.

1-Acyl triazenes can be prepared by acid-catalyzed hydration, gold/iodine-catalyzed oxidation, or oxyhalogenation of 1-alkynyl triazenes. Crystallographic analyses reveal a pronounced effect of the acyl group on the electronic structure of the triazene function. 1-Acyl triazenes display high thermal stability, and only moderate sensitivity toward hydrolysis.