Fig. 1. Optimized DFT/PBE50 structures of Zn salts. In red, symmetries: a Zn porphyrin (Zn-2); b Zn porphene (Zn-1); c bond length map for P2mm and P4mm forms of Zn-1; d Zn z-isoporphene; e Zn s-isoporphene. In parentheses, calculated energies relative to Zn-1 (kcal/mol.macrocycle). Black, green, and red circles are α, β, and meso carbon atoms, respectively; nitrogen atoms are blue, and larger purple circles are zinc atoms. In free bases 1 and 2,they represent two diagonally disposed H atoms. Red lines define unit cells: Zn-1:8.26Å×8.36Å (P2mm) or 8.29 Å × 8.29 Å (P4mm). From T.F. Magnera et al., Nat Commun 14, 6308 (2023)
Most two-dimensional materials (substances with a thickness of a few nanometers or less) such as graphene, silicene, germanene, and the transition metal dichalcogenides are inorganic, with properties that resist tuning. But they are prime candidates for elucidating tuning methods because their unique properties make them excellent candidates for a wide range of practical applications including nanoelectronics, spintronics, photonics, electrocatalysis, separations, and more.
A team of researchers from the University of Colorado, Boulder; the Czech Academy of Sciences; The University of Chicago; and the National Renewable Energy Laboratory elected to prepare and study a new two-dimensional material, Zn porophene, which had previously existed only as a hypothetical organic metalloporphene.
The material for study was synthesized on a water surface via two-dimensional oxidative polymerization of a Langmuir layer of Zn porphyrin with K2IrCl6.
The team employed a variety of research techniques including grazing incidence x-ray diffraction and x-ray reflectivity at the Liquid Surface/Interface X-ray Scattering facility at the NSF’s ChemMatCARS 15-ID x-ray beamlime of the Advanced Photon Source, Argonne National Laboratory.
Their results refute earlier theory that posited metallic conductivity for the heretofore unstudied material. It turns out that Zn porophene is, in reality, a p-type semiconductor, an intrinsic semiconductor doped with boron or indium. This state of semiconduction stems from a predicted unit-cell Peierls distortion from square to rectangular, much like bond-lengths apparent from the altering of anti-aromatic molecules. The potential for desirable tunability arises from the reversible insertion of certain metal ions, possibly carrying a fifth or sixth ligand. A potential application is preparation of circuit patterns on an atomic canvas without removing any π centers from conjugation.
See: Thomas F. Magnera1, PaulI.Dron1,2, Jared P. Bozzone1, Milena Jovanovic1 Igor Rončević2, Edward Tortorici1, Wei Bu3, Elisa M. Miller4, Charles T. Rogers1, and Josef Michl1,2*, “Porphene and porphite as porphyrin analogs of graphene and graphite,” Nat Commun 14, 6308 (2023).
Author affiliations: 1University of Colorado, Boulder; 2,Czech Academy of Sciences; 3The University of Chicago, 4National Renewable Energy Laboratory
Correspondence: *josef.michl@colorado.edu
We thank Dr. Binhua Lin (University of Chicago) and the ChemMatCARS Sector 15 facility, supported by NSF/CHE-1834750, for assistance with GIXD and XR at APS, an Office of Science User Facility operated for DOE by Argonne and supported by DOE under DE-AC02-06CH11357. This work was supported by the following entities: (i) Army Research Laboratory and Army Research Office grant W911NF-15-1-0435; (ii) U.S. National Science Foundation grant CHE 1900226; (iii) DARPA grant HR00111810006; (iv) University of Colorado Boulder Research Computing Group, funded by National Science Foundation grants ACI-1532235 and ACI-1532236, and Colorado State University; (v) University of Colorado Boulder; (vi) Institute of Organic Chemistry and Biochemistry, RVO: 61388963; (vii) The Czech Science Foundation grant 20-03691X; (viii) Czech Ministry of Education, Youth and Sports grant e-INFRA CZ, ID:90140; (ix) Wallonia-Brussels International Excellence Grant; (x) Department of Energy Office of Science, BES, Division of Chemical Sciences, Geosciences and Biosciences, Solar Photochemistry; (xi) Alliance for Sustainable Energy, LLC, operating NREL for Department of Energy grant DE-AC36-08GO28308.
For information on liquid surface/interface studies at NSF’s ChemMatCARS contact
Wei Bu
(630) 252-0470
weibu@uchicago.edu