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  • Substituent and isomeric effects on self-assembled phthalocyanine monolayers on HOPG as studied by scanning tunneling microscopy and DFT calculations

This content will become publicly available on February 1, 2026

Title: Substituent and isomeric effects on self-assembled phthalocyanine monolayers on HOPG as studied by scanning tunneling microscopy and DFT calculations
A comprehensive Scanning Tunneling Microscopy (STM)-driven ab initio investigation was conducted to explore the effects of peripheral substitution and central metalation on the molecular self-assembly of phthalocyanines on highly oriented pyrolytic graphite (HOPG). This study reports, for the first time, the self-assembly behavior of phthalocyanines with phenoxy and ethoxy substitutions and Co and Mg as central metals. Through periodic boundary simulations, we demonstrate that the peripheral substitutions significantly influence the energetic stability and monolayer structure, while central metal variations play a minor role. Our findings suggest that phthalocyanines with identical peripheral substitutions exhibit similar unit cell structures on Highly Oriented Pyrolytic Graphite (HOPG), regardless of the central metal. Furthermore, while substituent positional isomerism does not significantly impact the adsorption energy, the orientation of the peripheral substituents critically affects intermolecular interactions, influencing the stability of the monolayers. The study also reveals that octa-substituted phthalocyanines, such as H2Pc(OPh)8, form more stable, well-packed monolayers compared to tetra-substituted derivatives, like H2Pc(OEt)4, which exhibit phase segregation and disorder. Additionally, solvent molecules such as phenyl octane (PhOct) stabilize the disordered H2Pc(OEt)4monolayers by filling cavities between molecules. These results offer valuable insights into the design principles for engineering stable phthalocyanine monolayers, contributing to advancements in surface chemistry and materials science.  more » « less
Award ID(s):
2306316 2306317
PAR ID:
10589211
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
worldscinet
Date Published:
Journal Name:
Journal of Porphyrins and Phthalocyanines
Volume:
29
Issue:
01n02
ISSN:
1088-4246
Page Range / eLocation ID:
250 to 261
Subject(s) / Keyword(s):
self-assembly phthalocyanine monomer STM DFT adsorption isomeric effects
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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