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 π–π 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-1-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.