Porphyrin Boxes: Rationally Designed Porous Organic Cages

Abstract

The porphyrin boxes (PB-1 and PB-2), which are rationally designed porous organic cages with a large cavity using well-defined and rigid 3-connected triangular and 4-connected square shaped building units are reported. PB-1 has a cavity as large as 1.95 nm in diameter and shows high chemical stability in a broad pH range (4.8 to 13) in aqueous media. The crystalline nature as well as cavity structure of the shape-persistent organic cage crystals were intact even after complete removal of guest molecules, leading to one of the highest surface areas (1370 m(2) g(-1)) among the known porous organic molecular solids. The size of the cavities and windows of the porous organic cages can be modulated using different sized building units while maintaining the topology of the cages, as illustrated with PB-2. Interestingly, PB-2 crystals showed unusual N2 sorption isotherms as well as high selectivity for CO2 over N2 and CH4 (201 and 47.9, respectively at 273 K at 1 bar).

Topological landscapes of porous organic cages

“…and triamines by Hong et al (for which crystal structures are available); the resultant molecules showed selectivity for small gases. 68 The range of shapes possible for the Tet 6 Tri 8 topology spans from a rhombic dodecahedron 32 through an octahedron to a cube 68 as shown in Fig. 13.…”

Selective C70 encapsulation by a robust octameric nanospheroid held together by 48 cooperative hydrogen bonds

“…An established pathway to spherical structures involves the careful design and synthesis (often multi-stage) of an organic ligand with precisely spaced functional groups. Nanocapsules can be produced via reversible covalent bonds such as disulfide1314, boronic esters1516 and imines171819202122 or supramolecular interactions such as coordinative bonds23242526 and hydrogen bonding2728293031, the last being exemplified in the present work.…”

Kovalente organische Netzwerke und Käfigverbindungen: Design und Anwendungen von polymeren und diskreten organischen Gerüsten

“…Isostrukturelle Reihen von Käfigen liefern tiefere Einblicke in Struktur-Porositäts-Beziehungen. [108,299,300] Sowohl COFs als auch Käfige haben sich mittlerweile als permanent porçse Materialien etabliert, und auf den ersten Blick gibt es keine offensichtliche Präferenz füre ine der beiden Materialklassen. [138] In geordneten Phasen sind jedoch grçßere Unterschiede zu beobachten, die auf einen signifikanten Beitrag von extrinsischer Porositäti nfolge des unterschiedlichen Packungsverhaltens im Kristall schließen lassen.…”