Supramolecular Architecturing of Quantum Box Arrays from Functionalized Porphyrins and Exploring Their Quantum States

Our research is based on the analysis of structure-function correlations for a broad spectrum of functionalized porphyrins and phthalocyanines in their propensity to create increasingly complex and functional on surface architectures. [1] Thereby we use porphyrin and phthalocyanine functionalization and synthesis, ‘by design’, or ‘on-surface-supramolecular chemistry’ to create structures with specific physical properties towards e.g. future quantum devices. By using a fluoro-bi-phenyl functionalized porphyrin to create a stable, porous organic network, we manufacture arrays of identical quantum boxes. These boxes contain a specific quantum well state arising from the confinement of the electronic (Shockley) surface state within the pores. We show that the electronic quantum box state as well as the interbox coupling can be modified locally by adsorbates, e.g. C60, interacting with the barrier. In view of the wealth of available and differently acting adsorbates, this approach allows for the engineering of quantum states in on-surface network architectures. Thus, by their dance on the nose of the ‘devil’ [3], porphyrins and phthalocyanines justify the emergence of ‘on-surface supramolecular physics’ as reflected by ongoing and future research work. Fig. 1) Adsorbate-induced modification of the confining barriers in a quantum box array formed by a functionalized fluoro-bi-phenyl porphyrin on Ag(111). (Taken from [2]) [1] N. Wintjes et al. Two-dimensional phase behavior of a bimolecular porphyrin system at the solid-vacuum interface, J. Am. Chem. Soc. 2010, 132, 21, 7306-7311; N. Wintjes et al., Supramolecular synthons on surfaces: Controlling dimensionality and periodicity of tetraarylporphyrin assemblies by the interplay of cyano and alkoxy substituents Chem. Eur. J. 2008, 14, 5794. [2] S. Nowakowska et al., Adsorbate-induced modification of the confining barriers in a quantum box array, ACS Nano 2018, 12, 768. [3] W. Pauli “God made the bulk; surfaces were invented by the devil.” Quoted, e.g. in the Preface of A. Zangwill, Physics at Surfaces, Cambridge University Press, 1988. ISBN 978-0-521-34752-5 Figure 1