From chaos to order: Chain-length dependence of the free energy of formation of meso-tetraalkylporphyrin self-assembled monolayer polymorphs

Reimers, JR; Panduwinata, D; Visser, J; Chin, Y; Tang, C; Goerigk, L; Ford, MJ; Baker, M; Sum, TJ; Coenen, MJJ; Hendriksen, BLM; Elemans, JAAW; Hush, NS; Crossley, MJ

From chaos to order: Chain-length dependence of the free energy of formation of meso-tetraalkylporphyrin self-assembled monolayer polymorphs

Reimers, JR

Panduwinata, D Visser, J Chin, Y Tang, C Goerigk, L Ford, MJ

Baker, M Sum, TJ Coenen, MJJ Hendriksen, BLM Elemans, JAAW Hush, NS Crossley, MJ

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Publication Type:: Journal Article
Citation:: Journal of Physical Chemistry C, 2016, 120 (3), pp. 1739 - 1748
Issue Date:: 2016-01-28

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Field	Value	Language
dc.contributor.author	Reimers, JR https://orcid.org/0000-0001-5157-7422	en_US
dc.contributor.author	Panduwinata, D	en_US
dc.contributor.author	Visser, J	en_US
dc.contributor.author	Chin, Y	en_US
dc.contributor.author	Tang, C	en_US
dc.contributor.author	Goerigk, L	en_US
dc.contributor.author	Ford, MJ https://orcid.org/0000-0002-8595-5900	en_US
dc.contributor.author	Baker, M	en_US
dc.contributor.author	Sum, TJ	en_US
dc.contributor.author	Coenen, MJJ	en_US
dc.contributor.author	Hendriksen, BLM	en_US
dc.contributor.author	Elemans, JAAW	en_US
dc.contributor.author	Hush, NS	en_US
dc.contributor.author	Crossley, MJ	en_US
dc.date.available	2020-05-25T19:03:51Z
dc.date.issued	2016-01-28	en_US
dc.identifier.citation	Journal of Physical Chemistry C, 2016, 120 (3), pp. 1739 - 1748	en_US
dc.identifier.issn	1932-7447	en_US
dc.identifier.uri	http://hdl.handle.net/10453/42187
dc.description.abstract	© 2016 American Chemical Society. We demonstrate that systematic errors can be reduced and physical insight gained through investigation of the dependence of free energies for meso-tetraalkylporphyrin self-assembled monolayers (SAMs) polymorphism on the alkyl chain length m. These SAMs form on highly ordered pyrolytic graphite (HOPG) from organic solution, displaying manifold densities and atomic structures. SAMs with m = 11-19 are investigated experimentally while those with m = 6-28 are simulated using density-functional theory (DFT). It is shown that, for m = 15 or more, the alkyl chains crystallize to dominate SAM structure. Meso-tetraalkylporphyrin SAMs of length less than 11 have never been observed, a presumed effect of inadequate surface attraction. Instead, we show that free energies of SAM formation actually enhance as the chain length decreases. The inability to image regular SAMs stems from the appearance of many polymorphic forms of similar free energy, preventing SAM ordering. We also demonstrate a significant odd/even effect in SAM structure arising from packing anomalies. Comparison of the chain-length dependence of formation free energies allows the critical dispersion interactions between molecules, solvent, and substrate to be directly examined. Interpretation of the STM data combined with measured enthalpies indicates that Grimme's D3 explicit-dispersion correction and the implicit solvent correction of Floris, Tomasi and Pascual Ahuir are both quantitatively accurate and very well balanced to each other.	en_US
dc.relation.ispartof	Journal of Physical Chemistry C	en_US
dc.relation.isbasedon	10.1021/acs.jpcc.5b11621	en_US
dc.subject.classification	Physical Chemistry	en_US
dc.title	From chaos to order: Chain-length dependence of the free energy of formation of meso-tetraalkylporphyrin self-assembled monolayer polymorphs	en_US
dc.type	Journal Article
utslib.citation.volume	3	en_US
utslib.citation.volume	120	en_US
utslib.for	0306 Physical Chemistry (incl. Structural)	en_US
utslib.for	0912 Materials Engineering	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	09 Engineering	en_US
utslib.for	10 Technology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/DVC (Research)
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
utslib.copyright.status	open_access
pubs.issue	3	en_US
pubs.publication-status	Published	en_US
pubs.volume	120	en_US

Abstract:

© 2016 American Chemical Society. We demonstrate that systematic errors can be reduced and physical insight gained through investigation of the dependence of free energies for meso-tetraalkylporphyrin self-assembled monolayers (SAMs) polymorphism on the alkyl chain length m. These SAMs form on highly ordered pyrolytic graphite (HOPG) from organic solution, displaying manifold densities and atomic structures. SAMs with m = 11-19 are investigated experimentally while those with m = 6-28 are simulated using density-functional theory (DFT). It is shown that, for m = 15 or more, the alkyl chains crystallize to dominate SAM structure. Meso-tetraalkylporphyrin SAMs of length less than 11 have never been observed, a presumed effect of inadequate surface attraction. Instead, we show that free energies of SAM formation actually enhance as the chain length decreases. The inability to image regular SAMs stems from the appearance of many polymorphic forms of similar free energy, preventing SAM ordering. We also demonstrate a significant odd/even effect in SAM structure arising from packing anomalies. Comparison of the chain-length dependence of formation free energies allows the critical dispersion interactions between molecules, solvent, and substrate to be directly examined. Interpretation of the STM data combined with measured enthalpies indicates that Grimme's D3 explicit-dispersion correction and the implicit solvent correction of Floris, Tomasi and Pascual Ahuir are both quantitatively accurate and very well balanced to each other.

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http://hdl.handle.net/10453/42187