Competing Intermolecular and Molecule-Surface Interactions: Dipole-Dipole-Driven Patterns in Mixed Carborane Self-Assembled Monolayers

0584549 - ÚACH 2025 RIV US eng J - Journal Article
White, K. E. - Avery, E. - Cummings, E. - Hong, Z. - Langecker, Jens - Vetushka, Aliaksi - Dušek, Michal - Macháček, Jan - Višňák, Jakub - Endres, J. - Bastl, Zdeněk - Mete, E. - Alexandrova, A. N. - Baše, Tomáš - Weiss, P. S.
Competing Intermolecular and Molecule-Surface Interactions: Dipole-Dipole-Driven Patterns in Mixed Carborane Self-Assembled Monolayers.
Chemistry of Materials. Roč. 36, č. 4 (2024), s. 2085-2095. ISSN 0897-4756. E-ISSN 1520-5002
R&D Projects: GA MŠMT(CZ) LTAIN19152; GA MŠMT EF16_026/0008382; GA MŠMT(CZ) LM2018096
Research Infrastructure: e-INFRA CZ - 90140
Institutional support: RVO:61388980 ; RVO:68378271 ; RVO:61388955
Keywords : Molecular interactions * Molecules * Molecular structure * Scanning tunneling microscopy * Supramolecular chemistry
OECD category: Inorganic and nuclear chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D); Physical chemistry (UFCH-W)
Impact factor: 8.6, year: 2022
Method of publishing: Limited access
https://pubs.acs.org/doi/10.1021/acs.chemmater.3c03210

Carboranedithiol isomers adsorbing with opposite orientations of their dipoles on surfaces are self-assembled together to form mixed monolayers where both lateral dipole-dipole and lateral thiol-thiolate (S-H···S) interactions provide enhanced stability over single-component monolayers. We demonstrate the first instance of the ability to map individual isomers in a mixed monolayer using the model system carboranedithiols on Au{111}. The addition of methyl groups to one isomer provides both an enhanced dipole moment and extra apparent height for differentiation via scanning tunneling microscopy (STM). Associated computational investigations rationalize favorable interactions of mixed pairs and the associated stability changes that arise from these interactions. Both STM images and Monte Carlo simulations yield similarly structured mixed monolayers, where approximately 10% of the molecules have reversed dipole moment orientations but no direct chemical attachment to the surface, leading to homogeneous monolayers with no apparent phase separation. Deprotonating the thiols by depositing the molecules under basic conditions eliminates the lateral S-H···S interactions while accentuating the dipole-dipole forces. The molecular system investigated is composed of isomeric molecules with opposite orientations of dipoles and identical surface packing, which enables the mapping of individual molecules within the mixed monolayers and enables analyses of the contributions of the relatively weak lateral interactions to the overall stability of the assemblies.
Permanent Link: https://hdl.handle.net/11104/0352461