Electrically Conductive π-Intercalated Graphitic Metal–Organic Framework Containing Alternate π-Donor/Acceptor Stacks

Published

June 26, 2023

Author(s)

Ashok Yadav, Shiyu Zhang, Paola Benavides, Wei Zhou, Sourav Saha

Abstract

Electrical conductivity of metal-organic frameworks (MOFs) is a function of charge-carrier density and long-range charge transport capability. Although two-dimensional graphitic MOFs (GMOF) exhibit high intrinsic conductivity (σ ≥ 1 S/m) chiefly due to efficient through-bond charge movement within the hexagonal sheets consisting of metal-ligand coordination networks, less efficient out-of-plane charge movement through slipped-parallel stacked layers often creates large disparities between anisotropic conductivities in orthogonal directions and limits the bulk conductivity. Herein, we demonstrate a novel strategy to boost out-of-plane charge movement capacity and the bulk conductivity of GMOFs by developing the first π-intercalated GMOF (iGMOF-1) containing built-in alternating π-donar/acceptor stacks of π-donor 2,3,6,7,10.11-hexaminotriphenylene (HATP) ligands of Cu₃(HATP)₂ scaffold and non-coordinatively intercalated π-acidic hexacyanotriphenylene (HCTP) molecules. Since post-synthetic guest intercalation between closely π-stacked GMOF layers is not feasible, iGMOF-1 was prepared in a bottom-up fashion by introducing Cu²⁺ to preassembled supramolecular [HATP/HCTP]_{n array. iGMOF-1 pellets consistently displaced an order of magnitude higher electrical conductivity and notable smaller activation energy than Cu}d3^(HATP)₂ pellets (σ_average = 25 vs. 2 S/m, E_a = 36 vs. 65 meV) prepared and measured under the same conditions, which can be attributed to improved out-of-plane charge movement through the alternating HATP/HCTP stacks present in the former, as both materials possessed similar in-plane through-bond charge transport pathways. This breakthrough clears the access to other iGMOFs containing built-in alternating π-donor/acceptor stacks of different redox-complementary ligands and intercalated guests that can precisely regulate the efficacy of out-of-plane charge movement, reduce the differences between anisotropic conductivity, and thereby boost their bulk conductivity.

Citation

Journal of American Chemical Society

Volume

62

Issue

26

Pub Type

Journals

Download Paper

https://doi.org/10.1002/anie.202303819

Local Download

Keywords

Porous Material, Electrical Conductivity, Intercalation, Charge Transfer

Citation

Yadav, A. , Zhang, S. , Benavides, P. , Zhou, W. and Saha, S. (2023), Electrically Conductive π-Intercalated Graphitic Metal–Organic Framework Containing Alternate π-Donor/Acceptor Stacks, Journal of American Chemical Society, [online], https://doi.org/10.1002/anie.202303819, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934947 (Accessed April 30, 2024)