The 4th International Conference on Matter and Radiation at Extremes (ICMRE 2019)

497 / 2019-03-18 22:32:16

Reaction under Pressure: Compression-Induce Polymerization and Isomerization

high pressure,pressure-induced polymerization,compression,isomerization,cycloaddition

Plenary track > High Pressure Physics and Materials Science

Controlled cycloaddition reactions in solid state have great potential in organic syntheses. We have demonstrated polymerization through a copper-free 1,3-dipolar cycloaddition of azide and alkyne at room temperature in the solid state. Crystal packing facilitated by arene-perfluoroarene interactions offered a desirable spatial arrangement of the reacting functional groups, and therefore promoted a relatively well-controlled regioselective “click” polymerization giving the 1,4-triazole product. This AAC reaction in the solid state was found to be accelerated by high pressure, originated from the elevated substrate energy and decreased activation energy. A series of molecules featuring different linkers joining aromatic and fluorinated aromatic moieties, carrying the azide and alkyne groups respectively, are synthesized and their reactions show preferred regioselectivity for 1,4-triazole products.
The isomerization of spiropyrans and phenolphthalein in crystals was realized under high pressure, and corresponding mechanochromic response was visible to naked eyes. Based on this, a series of bi-chromophoric derivatives were synthesized and developed for multi-mode switching and multi-colored mechanochromic materials. They responded to both anisotropic grinding and isotropic compression. The mechanochromic property of these compounds induced by pressure provide more insights into chemical reactions under extreme conditions.