3D Cage COFs: A Dynamic Three-Dimensional Covalent Organic Framework with High-Connectivity Organic Cage Nodes

Abstract

Three-dimensional (3D) covalent organic frameworks (COFs) are rare because there is a limited choice of organic building blocks that offer multiple reactive sites in a polyhedral geometry. Here, we synthesized an organic cage molecule ( Cage-6-NH 2 ) that was used as a triangular prism node to yield the first cage-based 3D COF, 3D-CageCOF-1 . This COF adopts an unreported 2-fold interpenetrated acs topology and exhibits reversible dynamic behavior, switching between a small-pore ( sp ) structure and a large-pore ( lp ) structure. It also shows high CO 2 uptake and captures water at low humidity (<40%). This demonstrates the potential for expanding the structural complexity of 3D COFs by using organic cages as the building units.

Three-Dimensional Triptycene-Based Covalent Organic Frameworks with ceq or acs Topology

“…35 Subsequently, Cooper and co-workers also reported the first cage-based 3D COF, 3D-CageCOF-1, which is fabricated by an organic cage molecule as a triangular prism node and adopts a 2-fold interpenetrated acs topology. 36 It must be noted, however, that except for a few successful examples, 3D COFs using high-connectivity monomers still remain largely unexplored.…”

Electrochemical Recognition of Aromatic Species with Ferrocenylated 1,3,5‐Triazine‐ or 1,3,5‐Triphenylbenzene‐Containing Highly Organized Molecules

“…[7][8][9] Cage or cage-like compounds, which are commonly synthesized by utilizing dynamic covalent chemistry concepts starting from various building blocks, act as the prominent class of highly organized organic compounds for various applications. [10][11][12][13][14][15] Importantly, the introduction of redox-active species to the above-discussed molecules is an interesting approach toward tuning their properties and functions and opening new areas of applications. [16][17][18][19] Ferrocene (Fc), a redox-active metallocene, is commonly a first-or best-choice molecule for such purpose, because of its stability in air, good solubility in many organic solvents, as well as its electrochemical and thermal stability.…”

π‐Interpenetrated 3D Covalent Organic Frameworks from Distorted Polycyclic Aromatic Hydrocarbons

“…[2a-d,f-h,j,k,m,o] This is in part because of the low number of 3D organic monomers available, their limited geometries (imposed by the sp, sp 2 and sp 3 hybridization of carbon), and reduced points of extension. For instance, most of the reported 3D COFs have been obtained from tetrahedral (T d ) [4,5] monomers and only a few exceptions of 3D COFs have been obtained from triangular (D 3 ), [6] square (D 4 ), [6] triangular prismatic (D 3h ) [7] and cubic (O h ) [8] monomers. This is illustrated by the small number of topologies reported for 3D COFs (acs, [7b] bcu, [8] bor, [5e] ctn, [5e] dia, [5a-d] ffc, [9] fjh, [6c] lon, [5a] pts, [4, 5f-i] rra, [5j] srs, [6a] stp, [7a] tbo [6b] ), compared to the large number of topologies reported for metal-organic frameworks (> 60).…”

“…Although interpenetration is often regarded as something to be avoided because of its detrimental effect on porosity, [2d,l,n,o] its potential benefits on the overall properties of 3D COFs remains practically unexplored. [11] Herein, we report the synthesis of 3D COFs from a distorted polycyclic aromatic hydrocarbon monomer with a triangular antiprismatic (D 3d ) structure, namely 2,3, 6,7,10,11,14,15,18,19,22,23-dodecahydroxy-cata-hexabenzocoronene (3D-HBC, Figure 1 A). The structure of 3D-HBC deviates from the typical graphitic geometries because of the steric congestion between hydrogens on the peripheral rings, which forces, alternately, the catechol residues on the outer rim above and below the coronene plane.…”

“…3D-HBC was synthesized by ether cleavage of 2,3, 6,7,10,11,14,15,18,19,22,23-dodecamethoxy-cata-hexabenzocoronene [12] in the presence of BBr 3 in a quantitative yield. Marta-COF-3 and 4 were synthesized by solvothermal condensation of 3D-HBC with benzene-1,4-diboronic acid and with pyrene-2,7-diboronic acid, respectively (Figure 1), in N,N-dimethylacetamide/mesitylene (1:1, v/v) at 140 8C for 7 days in sealed pre-scored ampoules, which afforded green crystalline powders in % 90 % yields.…”