Observation of Interpenetration Isomerism in Covalent Organic Frameworks

We report herein the first example of interpenetration isomerism in covalent organic frameworks (COFs). As a well-known three-dimensional (3D) COF, COF-300 was synthesized and characterized by the Yaghi group in 2009 as a 5-fold interpenetrated diamond structure (<b><i>dia-c5</i></b> topology). We found that adding an aging process prior to the reported synthetic procedure afforded the formation of an interpenetration isomer, <b><i>dia-c7</i></b> COF-300. The 7-fold interpenetrated diamond structure of this new isomer was identified by powder X-ray diffraction and rotation electron diffraction analyses. Furthermore, we proposed a universal formula to accurately determine the number of interpenetration degrees of <b><i>dia</i></b>-based COFs from only the unit cell parameters and the length of the organic linker. This work not only provides a novel example to the category of interpenetration isomerism but also provides new insights for the further development of 3D COFs

An Open-Framework Aluminophosphite with Face-Sharing AlO₆ Octahedra Dimers and Extra-Large 14-Ring Channels

PKU-25Al, an open-framework aluminophosphite possessing extra-large intersecting 14-ring (14R) channels and a novel Al/P ratio of 9/14, was hydrothermally synthesized using commercially available 4-dimethylaminopyridine (DMAP) as organic structure-directing agents (OSDA). Two types of secondary building units (SBUs), SBU-1 with 6*1 units and racemic SBU-2 composed of two chiral 41 units, are utilized to construct the porous layers with a 4.6.12-net topology and the chains with unprecedented face-sharing AlO₆ octahedra dimers, respectively. Stringing the ABAB stacked layers via the chains would achieve the PKU-25Al framework with a unique topology as well as numerous chiral channel motifs. Meanwhile, the protonated DMAP molecules interact with the inorganic framework through hydrogen bonding and reside in the voids with an exceptional triangular pattern. PKU-25Al is the first aluminophosphite with extra-large channels and enriches the materials chemistry of the open-framework families with exceptive structures

An Open-Framework Aluminophosphite with Face-Sharing AlO₆ Octahedra Dimers and Extra-Large 14-Ring Channels

PKU-25Al, an open-framework aluminophosphite possessing extra-large intersecting 14-ring (14R) channels and a novel Al/P ratio of 9/14, was hydrothermally synthesized using commercially available 4-dimethylaminopyridine (DMAP) as organic structure-directing agents (OSDA). Two types of secondary building units (SBUs), SBU-1 with 6*1 units and racemic SBU-2 composed of two chiral 41 units, are utilized to construct the porous layers with a 4.6.12-net topology and the chains with unprecedented face-sharing AlO₆ octahedra dimers, respectively. Stringing the ABAB stacked layers via the chains would achieve the PKU-25Al framework with a unique topology as well as numerous chiral channel motifs. Meanwhile, the protonated DMAP molecules interact with the inorganic framework through hydrogen bonding and reside in the voids with an exceptional triangular pattern. PKU-25Al is the first aluminophosphite with extra-large channels and enriches the materials chemistry of the open-framework families with exceptive structures