Thermally Programmable Gas Storage and Release in Single Crystals of an Organic van der Waals Host

Abstract

A single crystal of a low density form of guest-free p-tert-butylcalix[4]arene can take up and release small guest molecules by controlling the temperature and pressure without changing the structure. Using NMR spectroscopy with flowing hyperpolarized xenon, we have shown that at room temperature access of xenon to the pore system is difficult, whereas it is relatively easy at 100 degrees C. There are good prospects for simple van der Waals materials such as the title material to be used as programmable zeolite mimics.

A Channel‐Free Soft‐Walled Capsular Calixarene Solid for Gas Adsorption

“…The position of the signal together with the sign and span of the CSA imply Xe occupies the space within the calixarene capsule. [16] Similar to microporous materials with nanochannels, [17] the signal moves downfield with increased Xe pressure (see the Supporting Information). An estimate of the void space inside the calixarene capsule using single-crystal X-ray diffraction data [12] (Figure 1) allows one to conclude that the deep cavity should not be available for Xe adsorption because it already contains a fragment of one of the acyl arms.…”

Diversity in Single- and Multiple-Component Crystals. The Search for and Prevalence of Polymorphs and Cocrystals

“…Cocrystals containing materials that are gaseous under ambient conditions (air, NO, SO 2 , and Xe) were found to be stable at ambient temperature, releasing the guests on heating. 99 Thus, the calixarene was suggested to be useful as a thermally programmable gas storage and release system. Triphenylphosphine oxide (TPPO) was found to cocrystallize with a variety of different organic compounds, including N-acetyl-p-toluenesulfonamide, acetanilide, triphenylcarbinol, saccharin, and phenol.…”

Pseudopolymorphism of Aliphatic Amine/4‐tert‐Butylcalix[4]arene Inclusion Compounds: Supramolecular Stabilization as a Route to Polar Clusters and Layers

“…[1][2][3][4][5][6][7][8][9][10] This research ultimately is driven by a desire to develop functional materials for various applications, such as gas adsorption [1,11,12] and catalysis. [13] The vast majority of such studies revolve around the synthesis of increasingly complex host molecules, so that insight into the weak forces guiding the self-assembly of such systems in the solid state is of secondary importance.…”

“…A family of interrelated polymorphs and pseudopolymorphs of 4tBC4A and its simple inclusion compounds have been characterized, including a low-density form which has shown potential as a gas adsorbent. [11,12,[24][25][26] In light of some of the elaborate covalently modified calixarene receptors previously reported, [16,27,28] self-assembly of 4tBC4A frameworks with guest molecules…”