Rectification in Supramolecular Zinc Porphyrin/Fulleropyrrolidine Dyads Self‐Organized on Gold(111)

Abstract

Self-assembled donor/acceptor dyads are of current interest as they are biomimetic to the natural photosynthetic conversion system. Herein, we present an ultrahigh-vacuum scanning tunneling microscopy and scanning tunneling spectroscopy (UHV-STM/STS) study of ex situ self-assembled supramolecular dyads consisting of fulleropyrrolidines (PyC(2)C(60)) axially ligated to zinc(II) tetraphenylporphyrin (ZnTPP), self organized on a 4-aminothiophenol (4-ATP) self-assembled monolayer on gold(111). These dyads show both bias-polarity-dependent apparent height in STM images and highly rectifying behavior in tunneling spectroscopy. First-principles density functional theory calculations clarify the conformational and electronic properties of the 4-ATP/ZnTPP/PyC(2)C(60) system. Interestingly, we find easier tunneling for electrons moving from the acceptor side of the dyads to the donor side, in the inverse-rectifying sense with respect to previously reported molecular rectifiers. Such behavior cannot be explained as an elastic resonant tunneling process, but it can by using a model based on the Aviram-Ratner mechanism.

High-conductance surface-anchoring of a mechanically flexible platform-based porphyrin complex

“…In addition, scanning tunneling spectra were recorded above the intact Por-TATA (figure 1(e)). While the relative intensity of the two molecular resonances may vary on different molecules, the data reveal an energy gap 4 of ± 2.80 0.05 eV as expected for Zn-porphyrin [33,34]. This agreement between the energy gap of Por-TATA and Zn-porphyrins suggests that the molecular orbitals of the porphyrin are only weakly perturbed by orbitals of the platform and metal surface.…”

Synthesis and conformation of a novel fluorescein–Zn-porphyrin dyad and intramolecular energy transfer

“…7,[20][21][22][23][24][25] Second, multichromophoric systems based on porphyrins are designed as artificial photosynthetic systems. [26][27][28][29][30][31] Although porphyrins are very often studied as dyads, there are only a handful of publications on labeling with a fluorescent molecule, without the intention to establish interactions between the two patterns, for environmental and/or health applications. For example, porphyrin-rhodamine 32 and porphyrin-fluorescein 33,34 dyads have already been synthesized, but without the intention of using them under biological conditions.…”

Electrostatic-Interaction-Induced Molecular Deposition of a Hybrid Bilayer on Au(111): A Scanning Tunneling Microscopy Study

“…The fabrication of well-defined functional molecular nanostructures on solid surfaces, such as molecular rectifiers, , molecular nanowires, − and molecular switches, is one of the crucial steps in the development of molecular nanodevices. Self-assembly is an increasingly used bottom-up strategy for achieving the controllable construction of surface molecular nanostructures. , The tailored construction of nanoarchitectures of organic molecules on solid surfaces with defined patterns in two dimensions has been successfully demonstrated in a wide variety of systems. − However, effective methodologies, such as layer-by-layer assembly, Langmuir–Blodgett film construction, and molecular layer deposition, have been developed to obtain thin organic films with ordered structures in the vertical direction. − …”