Diamondoid Porous Organic Salts toward Applicable Strategy for Construction of Versatile Porous Structures

To achieve efficient construction of organic porous materials with versatile properties, we propose a widely applicable novel strategy using organic salts comprising triphenylmethylamine (TPMA) and sulfonic acids. We demonstrate that TPMA and sulfonic acids having polyaromatic moieties give a new class of porous structures consisting of diamond networks, named as diamondoid porous organic salts (d-POSs). In the d-POSs, TPMA and the sulfonic acids are assembled into stable tetrahedral supramolecular clusters via charge-assisted hydrogen bonding as primary building blocks. Subsequently, the clusters are accumulated by pi-pi interactions between the polyaromatic moieties to yield the d-POSs through formation of the diamond networks. Large steric hindrance of the clusters prevents the diamond networks from constructing highly interpenetrated structures, giving continuous open channels. It should be noted that the interpenetration degree of the diamond networks is controlled by tuning the bulkiness of the cluster with alteration of sulfonic acids. Anthracene-2-sulfonic acid (2-AS) constructs a 3-fold structure with one-dimensional channels, whereas pyrene-l-sulfonic acid (1-PyS) yields a 2-fold structure having two-dimensional channels. Furthermore, the organic salt of TPMA and 2-AS also give polymorphic structures in response to host guest ratio and guest species, indicating not only their stability but the flexibility of the d-POSs.