Modular Total Synthesis in Reticular Chemistry

Abstract

The idea of modularity in organic total synthesis has promoted the construction of diverse targeted natural products by varying the building blocks and assembly sequences. Yet its utilization has been mainly limited to the synthesis of molecular compounds based on covalent bonds. In this work, we expand the conceptual scope of modular synthesis into framework materials, which bridges metal-and covalent organic frameworks (MOFs and COFs) hierarchically in reticular chemistry. While the assembly sequences are determined by the coordination or the covalent bond strengths, a modular synthesis strategy which progressively links simple building blocks into increasingly sophisticated superstructures was reported. As a result, a series of hierarchical COF-on-MOF structures with architectural intricacy were obtained through sequence-defined reactions of diverse building blocks. The tunability of spatial apportionment, compositions, and functionality was successfully managed in these framework materials. To the best of our knowledge, this is the first report on the synthesis of COF@MOF composites and also the first discovery of controlled COF alignment. This generalizable modularity strategy will not only accelerate the discovery of multicomponent framework materials by the hierarchical assembly of MOFs and COFs but also offer a predictable retrosynthetic route to smart materials with unusual tunability owing to the diverse inorganic or organic building units.

Hybrid Porous Crystalline Materials from Metal Organic Frameworks and Covalent Organic Frameworks

“…TFPT-TAPT Heterostructure Sequential COF-on-MOF growth Photocatalytic degradation [87] UiO-66 TAPB-DMTP MOF@COF Sequential COF-on-MOF growth - [88] Ce-MOF MCA Heterostructure Sequential MOF-on-COF growth Aptasensing [89] UiO-66-NH 2 TFPT-DETH MOF@COF Sequential COF-on-MOF growth Photocatalytic hydrogen evolution [90] MOF-5 M5C Heterostructure Sequential COF-on-MOF growth Dye adsorption [91] ZIF-90 COF-42 MOF@COF Sequential COF-on-MOF growth Biomacromolecule encapsulation [92] NH 2 -MIL-125 TAPB-PDA MOF@COF Sequential COF-on-MOF growth Photocatalytic oxidation [93] NH 2 -MIL-125 (Ti)@Pt DM-LZU1 MOF@COF Sequential COF-on-MOF growth Photocatalytic hydrogenation of olefins [94] UiO-66 COF1 (Tp-PDA)COF2 (Tp-TPE) MOF@COF Sequential COF-on-MOF growth Ratiometric fluorescence sensing [95] MOF-5 COF-303 COF@MOF Sequential MOF-on-COF growth - [96] Pd/UiO-66-NH 2 TAPT-Da MOF@COF Sequential COF-on-MOF growth Hydrogenation of olefins [97] Fe 3 O 4 @UiO-66 TzDa-COF Heterostructure Sequential COF-on-MOF growth Photocatalytic degradation [98] IR-MOF3 LZU1 MOF@COF Sequential COF-on-MOF growth Photocatalytic degradation [99] (Continued) Figure 2. Schematics of the preparation of the Pd-doped TiATA@LZU1 core-shell hybrid.…”

“…Recently, Zhou and coworkers have explored the use of crystals of a three‐dimensional (3D) COF as the core for stepwise growth of heterostructures, from which a generalizable modular strategy for complex hierarchical MOF/COF hybrids is proposed. [ 96 ] As shown in Figure 11 , highly crystalline COF‐303 was prepared as needle‐like crystals via the condensation of tetrakis(4‐formylphenyl)methane (TFM) with 1,4‐phenyldiamine (Pa) using the monomer‐mediated crystal growth method. [ 116 ] Thereafter, COF‐303 microrod crystals were immersed into the reaction system containing Zn(NO 3 ) 2 and terephthalic acid (H 2 BDC) for the growth of MOF‐5 crystal layer.…”

“…Scale bar is 100 μm in (d-f). Reproduced with permission [96]. Copyright 2020, American Chemical Society.…”

Directional asymmetry over multiple length scales in reticular porous materials

“…In addition, the same group modified their strategy to form Janus-like composites of MOFs with COFs, where the latter served as a core scaffold. 50 …”

Metal–Organic Framework‐Based Hybrid Frameworks

“…[ 30 ] Furthermore, Feng et al proposed a modularity strategy for the construction of hierarchically arranged framework materials. [ 75 ] Specifically, the whole integration was divided into smaller individual “modules” that could be exchanged to build different structures without affecting other modules. As a proof of concept, they chose COF‐303 as a module platform for the secondary growth of MOF‐5.…”