The Influence of Disorder in the Synthesis, Characterization and Applications of a Modifiable Two-Dimensional Covalent Organic Framework

Abstract

Two-dimensional covalent organic frameworks (2D-COFs) have been of increasing interest in the past decade due to their porous structures that ideally can be highly ordered. One of the most common routes to these polymers relies on Schiff-base chemistry, i.e., the condensation reaction between a carbonyl and an amine. In this report, we elaborate on the condensation of 3,6-dibromobenzene-1,2,4,5-tetraamine with hexaketocyclohexane (HKH) and the subsequent carbonylation of the resulting COF, along with the possibility that the condensation reaction on HKH can result in a trans configuration resulting in the formation of a disordered 2D-COF. This strategy enables modification of COFs via bromine substitution reactions to place functional groups within the pores of the materials. Ion-sieving measurements using membranes from this COF, reaction of small molecules with unreacted keto groups along with modeling studies indicate disorder in the COF polymerization process. We also present a Monte Carlo simulation that demonstrates the influence of even small amounts of disorder upon both the 2D and 3D structure of the resulting COF.

Two-Dimensional Polymers and Polymerizations

“…For example, linear polymer chain ends correspond to edge functionality in macromolecular sheets. Similarly, as bond breakage in a 1D polymer leads to chain scission, broken chemical bonds in the center of a 2D sheet typically introduce defects while leaving the overall 2D structure largely intact. − While linear block polymers have been explored extensively, block 2DPs have not yet been experimentally realized. However, it is conceivable that many block architectures could be prepared in the 2D limit, with opportunities to explore their assembly and phase separation.…”

Electrochemical and Spectroelectrochemical Studies on the Reactivity of Perimidine–Carbazole–Thiophene Monomers towards the Formation of Multidimensional Macromolecules versus Stable π-Dimeric States

“…However, electronic properties are also closely related to molecular chain orientation resulting from the formation of covalent linking and noncovalent intramolecular and intermolecular interactions, and so ordering on even the level of three dimensions (3D). Generally, two-, three- and multidimensional molecular network can be organized based on types of monomer linking (covalently, coordinating and/or supramolecular), where can indicate such as: covalent organic frameworks (COF) [ 5 , 6 ], coordination polymers [ 7 ], metal-organic frameworks (MOF) [ 8 ] and supramolecular polymers [ 9 , 10 , 11 ]. Supramolecular structures are self-assembled small molecules held together by reversible noncovalent interactions, such as hydrogen bonds [ 12 , 13 ], coordination [ 14 ], π–π stacking [ 15 , 16 ], and host-guest interactions [ 17 , 18 ], etc.…”

Computationally directed manipulation of cross-linked covalent organic frameworks for membrane applications

“…[1][2][3][4][5] Recently, a multitude of novel COFs and synthetic approaches have been published. [6][7][8][9][10][11] Other studies have looked closely at how to optimize current synthetic approaches 6,12 and at what molecular interactions are occurring between the stacked layers. 13 Maintaining the order of these 2D sheets remains a challenge, though, as membrane wetting can result in swelling or dispersion of the COF flakes.…”