Discrete Triptycene-Based Hexakis(metalsalphens): Extrinsic Soluble Porous Molecules of Isostructural Constitution

Abstract

In 2013 the concept of OMIMs (organic molecules of intrinsic microporosity) was introduced by McKeown et al. These OMIMs are constructed on the basis of rigid molecular cores such as triptycene, spirobifluorenes, and others. Like shape-persistent organic cages, these are soluble discrete molecules and therefore an interesting alternative to 3D, insoluble porous materials, such as metal-organic frameworks, covalent-organic frameworks, or zeolites. OMIMs are chemically and thermally robust because the formation of strong covalent bonds has been used for their synthesis. To date, a few OMIMs have been reported, though most of them did not contain any functional unit to enhance gas sorption properties. This work introduces an isostructural series of metal-salphene based OMIMs with different metal ions (Zn²⁺ , Ni²⁺ , Cu²⁺ , Pd²⁺ , and Pt²⁺ ) integrated into the backbone. The influence of the metal centers on interaction with gas molecules has been investigated by gas sorption experiments.

Keywords: gas sorption; metal coordination; porosity; salphens; triptycene.