A team of Korean researchers, affiliated with UNIST, has recently announced the principle of producing porous organic materials in the blink of an eye. This is similar to the mechanism of chemical reaction in explosives, in which pulling the trigger causes the detonator to explode.
The breakthrough has been led by Professor Jong-Beom Baek in the School of Energy and Chemical Engineering at UNIST. The study demonstrates a synthetic protocol for the formation of a 3D porous organic network via a solid-state explosion of organic single crystals.
Three-dimensional porous materials have a high surface area, which could be useful for various applications, such as catalytic supports, gas capture and storage, energy conversion and storage, optoelectronics and semiconductors. Typical examples are zeolites and zeolite-like materials. But in recent years, extensive studies have been conducted to produce porous materials from more durable organic materials. They make sure of a synthetic approach to produce a 3D porous organic network in liquid-phase reactions in the presence of suitable solvents and/or catalysts. However, the resultant products are of a low purity and therefore post-treatment for purification became necessary.
Professor Baek and his team introduced a new synthetic methodology for fabrication of a 3D porous organic network with high specific surface area via a solid-state explosion of organic single crystals containing primer molecules. The explosive reaction is realized by the Bergman reaction of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoathracene (HEA), which is a self-polymerizable trifunctional (M3) building block with three enediyne groups. In general, solid-organic materials can easily melt when heat is applied. However, their newly-developed HEA single crystals trigger an explosive Bergman reaction and quickly changes to 3D porous materials, without the presence of solvents and catalysts when heat is applied.
"Solid-state reaction can yield products of high purity and therefore post-treatment for purification may become not necessary," says Dr. Seo-Yoon Bae in the School of Energy and Chemical Engineering, the first author of the study. "Besides, the resultant products are of high purity and therefore they have more advantages than a solution or gas-phase reactions."
The HEA single crystal consists of nine HEA molecules with two acetone and one water molecules in the lattice. Huge exothermic heat is explosively released because the boiling point of water and acetone is low, according to the research team. Because water boils at 100°C and acetone boils at 56°C, there is an increase in the kinetic energies between the two molecules when heat is applied. Before the organic single crystals melt, the acetone and water molecules (primer to trigger explosion) is released outside, HEA molecules in the crystal lattice start rearranging and this is followed by huge exothermic heat proceeds.
The paper on this study was published in Nature Communications.