Synchronized Offset Stacking: A Concept for Growing Large-Domain and Highly Crystalline 2D Covalent Organic Frameworks

Abstract

Covalent organic frameworks (COFs), formed by reversible condensation of rigid organic building blocks, are crystalline and porous materials of great potential for catalysis and organic electronics. Particularly with a view of organic electronics, achieving a maximum degree of crystallinity and large domain sizes while allowing for a tightly π-stacked topology would be highly desirable. We present a design concept that uses the 3D geometry of the building blocks to generate a lattice of uniquely defined docking sites for the attachment of consecutive layers, thus allowing us to achieve a greatly improved degree of order within a given average number of attachment and detachment cycles during COF growth. Synchronization of the molecular geometry across several hundred nanometers promotes the growth of highly crystalline frameworks with unprecedented domain sizes. Spectroscopic data indicate considerable delocalization of excitations along the π-stacked columns and the feasibility of donor-acceptor excitations across the imine bonds. The frameworks developed in this study can serve as a blueprint for the design of a broad range of tailor-made 2D COFs with extended π-conjugated building blocks for applications in photocatalysis and optoelectronics.

Design Principles for Covalent Organic Frameworks in Energy Storage Applications

“…These improved COFs were used as effective scaffolds for photocatalytic hydrogen generation.S eemingly in contrast, ar eport by Bein and co-workers, who used an onplanar tetraphenylethylene linker,s howedt hat, if properly designed, nonplanar aromatic systems could "lock" COF layers into place, resulting in improved long-range crystallinity. [15] Electronic effects can also play ar ole, as demonstrated by Jiang et al through the use of electronically complementarym onomers. [15] Electronic effects can also play ar ole, as demonstrated by Jiang et al through the use of electronically complementarym onomers.…”

Equilibration of Imine‐Linked Polymers to Hexagonal Macrocycles Driven by Self‐Assembly

“…The product of this reaction, performed under identical reactionc onditions, exhibited as imilar GPC chromatogram ( Figure S4) and selectivity for the hexagonal structural by MALDI-MS ( Figure S5). [37][38][39] The long-range order of the aggregated macrocycles was characterized by in situ wide-angle X-ray scattering.A1-PDA macrocycle suspension in 1,4-dioxane providedd iffraction peaks consistent with ah exagonal packed arrangemento f macrocycles with P6 symmetry ( Figure 4A). These conditions delay the onset of macrocycle precipitation to approximately 35 min, providing more time to monitor the solution composition.…”

“…We prepared and isolated separate samples of the 1-PDA and 2-PDA polymers. [37][38][39] The long-range order of the aggregated macrocycles was characterized by in situ wide-angle X-ray scattering.A1-PDA macrocycle suspension in 1,4-dioxane providedd iffraction peaks consistent with ah exagonal packed arrangemento f macrocycles with P6 symmetry ( Figure 4A). When equal equivalents of the two polymers were mixed and redispersedi n1 ,4-dioxane in the presence of CF 3 CO 2 H, a nearly statistical distribution of macrocycles containing mixtures of 1 and 2 was obtained ( Figure 3).…”

Tunable Crystallinity and Charge Transfer in Two‐Dimensional G‐Quadruplex Organic Frameworks

“…[13] Themuch larger f(mXy-Pyr) = 828 8,however,make the mXy and Pyr moieties orthogonal to one another and prevent the stacking interaction. [13] Themuch larger f(mXy-Pyr) = 828 8,however,make the mXy and Pyr moieties orthogonal to one another and prevent the stacking interaction.…”