本文要点：
共价有机框架(COFs)是具有广泛应用可能性的结晶多孔材料，但其结构多样性仍然受到简单网络拓扑的限制，限制了功能的多样性。
为了应对这一挑战，作者开发了一种整合具有错配几何结构的连接子的策略，例如在2D瓷砖中整合了五边形图案的[4-c+2-c+3-c]系统。
这种方法的核心是长度比参数α的推导，它为评价三元体系中连接物的相容性提供了定量指导。
使用优化到理想α的模型系统，证明了精确的尺寸匹配能够形成定域固溶体和异质外延界面。
这些发现展示了扩展COFs结构和功能复杂性的途径，为定制材料设计开辟了新途径。
Figure 1: A: Phase diagram of a selection of possible periodic square triangle tilings, where mixed phases display pentagonal pores, B: Schematic of the pure phase COFs synthesized here.
Figure 2: A: Ternary diagram of the relative lengths of q, l and t in relation to α0 (normalized to q + l + t = 1 for each 3-tuple). The background shading indicates the deviation of α from α0 with white being the closest to α0. Each dot describes an element consisting of a 4-c, 2-c and 3-c building block. Each grid highlights a set of combinations for a fixed 4-c building block. The identity of each point can be determined from the legend. B: Depiction of the two pentagons with the linker lengths marked. C: Molecular structures of the fragments used for the calculations. The orientation of imines does not affect the distance calculations and was not varied.
Figure 3: Simulated PXRD of the hcb, mcm, cem-d and sql structures for the 1Q-8L-10T-COF system compared with HR-PXRD data (λ = 0.1653 Å) (A). Peak positions of the first and second reflex compared to the composition of the ternary COF(B), the size of the points reflect the FWHM. HR-PXRD data of mixed ternary COF (C).
Figure 4: PXRD of fine-grained ternary mixtures of 1Q-5L-10T-COF (ESI) (left) and 1Q-8L-10T-COF (right) (A) and peak fit each point was determined based on the relative FWHM of the peaks to one another at the given content of 1Q (B).
Figure 5: TEM image (A) of the local structure of the “random shape” phase of the 150%-8-1050%-COF showing adjacent hexagonal and tetragonal regions (B, C, F), four fused pentagons (D) similar to the pentagons observed in the mcm structure (G) and alternating spots and stripes (E) that could be attributed to a structural motif also occurring in the cem-d structure (H).
Figure 6: Heteroepitaxial interfaces in the 1Q-8L-10T-COF. A: TEM image of two different aligned heteroepitaxial interfaces between the sql phase and the hcb phase. Color overlays are based on the d-spacing observed in the corresponding regions: green higher d-spacing component (~2.94 nm) corresponding to the sql phase; blue corresponds to the lower d-spacing component (~2.41 nm), which corresponds to the hcb phase in this image. B, D: details of the grain boundaries and C,E: corresponding FFT images. F: simulated structure of how the epitaxial interface can be constructed between the sql 1Q-8L- and hcb 8L-10T COF.
Figure 7 Nitrogen sorption isotherms for the ternary COFs (A). The solid and open symbols represent adsorption and desorption, respectively. Column chart depicts the BET throughout the ternary COF mixtures. The color of the column corresponds to the color of the mixtures of the sorption isotherms.
https://chemrxiv.org/engage/chemrxiv/article-details/679a850881d2151a0274e78c
