Electrically Conductive 3D Metal–Organic Framework Featuring π-Acidic Hexaazatriphenylene Hexacarbonitrile Ligands with Anion–π Interaction and Efficient Charge-Transport Capabilities

Published

September 8, 2020

Author(s)

Ashok Yadav, Dillip K. Panda, Shiyu Zhang, Wei Zhou, Sourav Saha

Abstract

Owing to their unparalleled synthetic simplicity, structural tunability, and functional versatility, electrically conductive metal–organic frameworks (MOFs) have emerged as one of the most promising electronic materials of the 21^st century. With much of the recent efforts focused on developing conducting MOFs using various electron-rich aromatic ligands, electron-deficient (i.e.,π-acidic) N-heteroaromatic ligands with soft coordination sites have been largely overlooked. Encouraged by its dual capabilities to bind both cations and anions, herein, we introduced a highly π-acidic 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-heaxacarbonitrile (HATHCN) ligand to construct a novel 3D [Ag₂(HATHCN)(CF₃SO₃)₂] MOF where each ligand coordinated six Ag₊ ions with its four bidentate core-N atoms and four CN groups and engaged four TfO^– anions in anion–πinteraction with the aromatic core. The MOF features staircase-like chains made of alternating Ag⁺ cations and HATHCN ligands that can support through-bond charge movement, while the TfO^–/HATHCN interactions render the ligands a radical anion character. Computational studies revealed a fairly narrow electronic band gap (1.35 eV) foreshadowing high electrically conductivity and significant overlap between the Ag⁺-4d and ligand-2p orbitals in the valence band maximum and conduction band minimum, indicating the possibility of through-bond charge transport. The in-situ pressed MOF pellets displayed an impressive electrical conductivity (7.3×10^–2 S/m, 293 K) that ranked very high among 3D conductive MOFs. This study demonstrated for the first time that the anion–π interaction and through-bond charge transport capabilities of a π-acidic HATHCN ligand could lead to high electrical conductivity and narrow electronic band gap in 3D MOFs.

Citation

ACS Applied Materials and Interfaces

Volume

12

Issue

36

Pub Type

Journals

Download Paper

DOI Link

Keywords

porous materials, anion-induced electron transfer, band gap, electrical conductivity

Citation

Yadav, A. , Panda, D. , Zhang, S. , Zhou, W. and Saha, S. (2020), Electrically Conductive 3D Metal–Organic Framework Featuring π-Acidic Hexaazatriphenylene Hexacarbonitrile Ligands with Anion–π Interaction and Efficient Charge-Transport Capabilities, ACS Applied Materials and Interfaces, [online], https://doi.org/10.1021/acsami.0c12388 (Accessed May 10, 2024)