Science Daily August 25, 2020
To ensure safety and efficiency factories often need to be monitored for potentially toxic gasses or even excess humidity. Sensors for water vapor are particularly important for monitoring toxic gasses or even excess humidity. But they may have limited lifetimes or require external power. An international team of researchers (Japan, Spain) formed van der Waals porous crystal (VPC-1) from an aromatic dendrimer containing carbon rings anchored to a dibenzophenazine core. Even though van der Waals forces are usually considered to be relatively weak, the crystal stays together during operation. Upon exposure to water vapor, the planes of the outermost carbazole units in the crystal twist simultaneously. This motion changes the energies of the electronic orbitals, which cause the electrons to absorb different colors of light. The invention could lead to sensitive “vapochromic” sensors without the need for external power…read more. Open Access TECHNICAL ARTICLE
Schematic representations of the hydrochromism of VPC-1 upon hydration/dehydration. Credit: Communications Chemistry volume 3, Article number: 118 (2020)