Switching the Proton Conduction in Nanoporous, Crystalline Materials by Light
Müller, K. / Helfferich, J. /Zhao, F. / Verma, R. / Kanj, A.B. / Meded, V. / Bléger, D. / Wenzel, W. / Heinke, L. (2018)
Adv Mater, 2018, 30, 8, doi: 10.1002/adma.201706551
- Date: Januar 2018
Proton conducting nanoporous materials attract substantial attention with respect to applications in fuel cells, supercapacitors, chemical sensors, and information processing devices inspired by biological systems. Here, a crystalline, nanoporous material which offers dynamic remote-control over the proton conduction is presented. This is realized by using surface-mounted metal-organic frameworks (SURMOFs) with azobenzene side groups that can undergo light-induced reversible isomerization between the stable trans and cis states. The trans-cis photoisomerization results in the modulation of the interaction between MOF and guest molecules, 1,4-butanediol and 1,2,3-triazole; enabling the switching between the states with significantly increased (trans) and reduced (cis) conductivity. Quantum chemical calculations show that the trans-to-cis isomerization results in the formation of stronger hydrogen bridges of the guest molecules with the azo groups, causing stronger bonding of the guest molecules and, as a result, smaller proton conductivity. It is foreseen that photoswitchable proton-conducting materials may find its application in advanced, remote-controllable chemical sensors, and a variety of devices based on the conductivity of protons or other charged molecules, which can be interfaced with biological systems.