Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework

Abstract

We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni­(II) tetraaza[14]­annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = nitrogen) compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni­(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR).

Conductive Metallophthalocyanine Framework Films with High Carrier Mobility as Efficient Chemiresistors

“…It was determined as a p‐type semiconductor with a charge carrier density of 2.14×10 13 cm −3 and a carrier mobility of 0.15 cm 2 V s −1 . The mobility of NiPc‐CoTAA ranks as one of the highest values and is comparable with those of several landmark COF and MOF semiconductors (Table S3) [18–20] . Furthermore, its conductivity was evaluated using the four‐point probe measurement on a pressed powder pellet.…”

“…Several examples have been established based on this structural advantage, such as 2D‐NiPc‐BTDA COF, [19a] DMPc‐ADI‐COFs, [19b] and DA‐COF [19c] . Recently, a new conductive framework was successfully constructed with the Ni II tetraaza[14]annulene complex as the linkage [20] . The triphenylene‐based NiTAA‐MOF combined the structural advantages of conductive MOFs and COFs, simultaneously possessing the metal ions and covalent bonds in the network connectivity.…”

Electrical conductivity and magnetic bistability in metal–organic frameworks and coordination polymers: charge transport and spin crossover at the nanoscale

“…The out-of-plane disposition of layer fits better with a slipped-parallel stacking mode. 162 The structural differences commented above, give rise to acute differences in the porosity of MOGs. They are all in the microporous range (pore apertures from 0.2 to 20 nm), but the smaller pores of MOGs with benzene linkers logically yield lower values.…”

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronics

“…After the first 2D c-MOF reported by Yaghi group in 2012, 19 various ortho-substituted benzene-and triphenylene (TP)-based building blocks have been developed/employed for the formation of 2D c-MOFs, such as 1,2,3,4,5,6-hexahydroxybenzene (HHB), 39 1,2,3,4,5,6-hexaaminobenzene (HAB), 40 1,2,3,4,5,6benzenehexathiol (BHT, also denoted asHTB), 41 1,2,3,4,5,6benzenehexaselenol (HSeB), 42 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), 19 2,3,6,7,10,11-hexaaminotriphenylene (HATP), 43,44 2,3,6,7,10,11-triphenylenehexathiol (THT, also denoted as HTTP), 45 2,3,6,7,10,11-triphenylenehexaselenol (HSeTP). 46 Larger conjugated monomers have been developed and explored for the synthesis of 2D c-MOFs as well (Fig.…”