Seminar Series - Synthesis of Porphene, an Antiaromatic Analog of Graphene
12. 10. 2022 - 15:00
CEITEC BUT, Purkyňova 123, Brno - large meeting room S
Prof. Josef Michl
Department of chemistry, University of Colorado, Boulder, USA
Two-dimensional organic materials offer atomic precision for optoelectronics and energy-efficient nanoelectronics, but most are not easily patterned and tuned. The fully conjugated Zn-porphene, (C20N4Zn)4 has now been prepared from Zn porphyrin by oxidative polymerization on aqueous surface and transferred to solid substrates. Its structure was established by imaging as well as in-situ and ex-situ spectroscopy. Reversible insertion of other metal ions is possible and promises an atomic canvas for painting with thousands of distinct metal ions and ligands without taking any › centers out of conjugation. Unlike earlier computational results, which predicted a P4mm (D4h) square unit cell and metallic conductivity, ours resemble those for antiaromatic molecules and predict Zn-porphene to be a two-dimensional antiaromatic semiconductor with a pair of P2mm (D2h) rectangular unit cells, rapidly interconverting via a P4mm (D4h) square structure by tunneling and/or thermal excitation. This result is supported by measurements of electrical conductivity and of N(1s) chemical shift in X-ray photoelectron spectra.