A Dual Threat: Redox‐Activity and Electronic Structures of Well‐Defined Donor–Acceptor Fulleretic Covalent‐Organic Materials

Abstract

The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two‐ and three‐dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight‐fold conductivity enhancement. The first evaluation of redox behavior of buckyball‐ or tetracyanoquinodimethane‐integrated crystalline was conducted. In parallel with tailoring the D‐A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli‐controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials.

Confinement‐Driven Photophysics in Hydrazone‐Based Hierarchical Materials

“…First, the pore size of the selected scaffolds should be sufficient to accommodate bulky photochromic molecules. Second, the framework should provide the mechanisms for post‐synthetic installation of the hydrazone linkers (e.g., functional groups, “missing” linkers, or unsaturated metal nodes) [78–87] . Finally, the host should maintain structural integrity after coordinative immobilization of hydrazone derivatives and for the duration of the corresponding photophysical experiments.…”

Donor‐Acceptor Type Covalent Organic Frameworks

“…In addition to the dynamic covalent linkages, geometric matching of the monomers plays an important role in the synthesis of the targeted COFs. Based on the topological diagram, hexagonal 2D COFs could be generated with the combination of [C 3 + C 2 ] [14,35,46,49,52,53,57,62,63] or [C 3 + C 3 ]; [40b,48a] tet- ragonal 2D COFs could be formed from [C 4 + C 2 ] [34,42,47,51] or [C 4 + C 4 ], and [C 2 + D 2h ] may give rise to rhombic COFs with a single kind of pore [41b,44,54,58,59] or kagome type COFs with six small evenly-arranged trigonal pores surrounding a large hexagonal pore. Moreover, COFs containing unique small trigonal pores could be obtained through [C 6 + C 2 ], and asymmetric topologies could be accessed with a multi-component (MC) approach.…”

“…Even diverse electron donors, for example, thiophene, thienothiophene, carbazole, phenoxazine, phenazine and triphenylamine could combine with different electron acceptors, for example, benzophenone, benzothiadiazole, triazine, and fullerene to form DÀ A type small molecules and linear polymers for various applications. [44,9c] However, only a few kinds of building blocks have been used in DÀ A COFs, including C 4 symmetric porphyrin [56] and phathalocynanine, [34,47,51] C 3-geometric triphenylamine, [48a] triphenylbenzene, [52,53,61] triazine and triphenylene, [14,35,46,49,63] C 2 -type benzothiadiazole and bithiophene and D 2h tetraphenylethylene [55] and pyrene. [41,44,54,58,59] As a result, the topologies of DÀ A COFs are thus far only limited to hexagonal, [14,35,40b,46,48a,49,52,53,57,62,63] tetragonal[ 34,42,47,51] and rhombic [41b,44,54,56,58,59,60] lattices.…”

“…Redox behaviors of TCNQ-grafted COF exhibited less negative reduction and oxidation potentials compared with pure TCNQ. [52] The curved π-bowl (πB), i. e. corannulene or dibenzo [ghi,mno]fluoranthene, is an unique electron acceptor with distinct electronic properties from the planar aromatic hydrocarbons (Figure 6D). Rice et al reported a π-bowl containing DÀ A COF by a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction between azide-substituted [π-C 20 H 9 N 3 ] and ethynyl-incorporated COF.…”

Quantum Capacitance through Molecular Infiltration of 7,7,8,8-Tetracyanoquinodimethane in Metal–Organic Framework/Covalent Organic Framework Hybrids

“…Since Talin et al described the example of tuning the electrical conductivity in MOFs via the incorporation of redox-active 7,7,8,8-tetracyanoquinodimethane (TCNQ) within the pores of Cu 3 BTC 2 (also called HKUST-1; BTC= 1,3,5-benzenetricarboxylate), 21 a series of structural and computational studies were undertaken to explore the influence of the electronacceptor guest TCNQ on the electron-donor host MOFs or COFs. [34][35][36][37][38] Noteworthy, Feng et al have demonstrated the electronic doping of MOF with TCNQ by employing TCNQ@Cu 3 (BTC) 2 as an active material micro-supercapacitors. 39 Hitherto, the infiltration of TCNQ into MOFs@COFs and their application in energy storage is still unexplored.…”