Electronic energy levels of porphyrins are influenced by the local chemical environment

Abstract

Self-assembled islands of 5,10,15,20-tetrakis(pentafluoro-phenyl)porphyrin (2HTFPP) on Au(111) contain two bistable molecular species that differ by shifted electronic energy levels.

Light‐induced Photoswitching of 4‐(Phenylazo)benzoic Acid on Au(111)

“…Before azobenzene deposition, the gold sample was imaged under the STM to ensure proper surface cleaning. A ~1 mM solution of 4‐(phenylazo)benzoic acid (PABA) dissolved in chloroform was deposited on the clean Au surface using a pulsed‐solenoid valve in the vacuum chamber [24,68,69] . Gentle annealing of the sample was carried out at 343 K to remove excess solvent and study the effects of different molecular packing on the surface.…”

“…A.03 [73] . Simulated STM images were computed using the Tersoff Hamman approximation as done in prior papers [68,69,74–78] . The tip was modeled as an s‐orbital and the surface as featureless and having a constant density of states to reproduce a constant current experiment.…”

“…[73] Simulated STM images were computed using the Tersoff Hamman approximation as done in prior papers. [68,69,[74][75][76][77][78] The tip was modeled as an s-orbital and the surface as featureless and having a constant density of states to reproduce a constant current experiment. Through the Tersoff and Hamman approximation, the tunneling current is proportional to the local density of states, thus providing information on the local density of states at a specific energy and a discrete location.…”

Synthesis of extended covalently bound porphyrins on the Au(111) surface

“…39 STM images were simulated using the Tersoff and Hamann approximation 40,41 as done previously. 36,42,43 Molecular manipulation experiments were performed to determine the flexibility of the COFs and to corroborate that the molecules were covalently coupled. The pulse deposition of TBrPP leads to the formation of selfassembled porphyrin islands.…”

“…35 Moreover, recent studies have demonstrated that the Au(111) herringbone affects the electronic states of a TFPP porphyrin, leading to the formation of two equivalent conformations of the molecule with shifted electronic states. 36 Therefore, investigating the interplay between the underlying Au(111) substrate and its role in the electronic structure and chemical properties of porphyrins is crucial for further understanding. Here, the Au(111) herringbone plays a role in the self-assembly and on-surface metalation of a pulse-deposited solution of TBrPP.…”