The 3,4-dimethoxybenzyl group as solubilizing protective group for the in situ deprotection/deposition of extended aromatic thiolate monolayers
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While self-assembled monolayers (SAMs) of aromatic thiolates are frequently used in a wide range of applications, their formation is often hampered by the low solubilities of their precursors. Here we introduce the 3,4-dimethoxybenzyl group as a protective group for the thiol moiety, which increases the solubility and stability of the precursor, but becomes cleaved off during monolayer formation, especially at elevated temperature (60 °C) and in presence of protons (trifluoroacetic acid). For a series of substituted terphenylthiols as model systems, it could be demonstrated by using ellipsometry, infrared-reflection absorption spectroscopy, and scanning-tunneling microscopy that the resulting SAMs have the same structure and quality as the ones obtained from the respective unprotected thiols. The protective group has the additional advantage to be stable under Pd-catalyzed C–C bond formation reaction conditions, facilitating the syntheses of the respective precursors.
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The 3,4-dimethoxybenzyl group as solubilizing protective group for the in situ deprotection/deposition of extended aromatic thiolate monolayers
)
Abstract
While self-assembled monolayers (SAMs) of aromatic thiolates are frequently used in a wide range of applications, their formation is often hampered by the low solubilities of their precursors. Here we introduce the 3,4-dimethoxybenzyl group as a protective group for the thiol moiety, which increases the solubility and stability of the precursor, but becomes cleaved off during monolayer formation, especially at elevated temperature (60 °C) and in presence of protons (trifluoroacetic acid). For a series of substituted terphenylthiols as model systems, it could be demonstrated by using ellipsometry, infrared-reflection absorption spectroscopy, and scanning-tunneling microscopy that the resulting SAMs have the same structure and quality as the ones obtained from the respective unprotected thiols. The protective group has the additional advantage to be stable under Pd-catalyzed C–C bond formation reaction conditions, facilitating the syntheses of the respective precursors.
References(42)
Holmlin, R. E.; Haag, R.; Chabinyc, M. L.; Ismagilov, R. F.; Cohen, A. E.; Terfort, A.; Rampi, M. A.; Whitesides, G. M. Electron transport through thin organic films in metal-insulator-metal junctions based on self-assembled monolayers. J. Am. Chem. Soc. 2001, 123, 5075–5085.
Bowers, C. M.; Rappoport, D.; Baghbanzadeh, M.; Simeone, F. C.; Liao, K. C.; Semenov, S. N.; Żaba, T.; Cyganik, P.; Aspuru-Guzik, A.; Whitesides, G. M. Tunneling across SAMs containing oligophenyl groups. J. Phys. Chem. C 2016, 120, 11331–11337.
Zharnikov, M. Probing charge transfer dynamics in self-assembled monolayers by core hole clock approach. J. Electron Spectrosc. Rel. Phenom. 2015, 200, 160–173.
Borchert, J. W.; Weitz, R. T.; Ludwigs, S.; Klauk, H. A critical outlook for the pursuit of lower contact resistance in organic transistors. Adv. Mater. 2022, 34, 2104075.
Ried, W.; Freitag, D. Oligophenyls, oligophenylenes, and polyphenyls, a class of thermally very stable compounds. Angew. Chem., Int. Ed. 1968, 7, 835–844.
Shen, C.; Buck, M.; Wilton-Ely, J. D. E. T.; Weidner, T.; Zharnikov, M. On the importance of purity for the formation of self-assembled monolayers from thiocyanates. Langmuir 2008, 24, 6609–6615.
Lukkari, J.; Meretoja, M.; Kartio, I.; Laajalehto, K.; Rajamäki, M.; Lindström, M.; Kankare, J. Organic thiosulfates (bunte salts): Novel surface-active sulfur compounds for the preparation of self-assembled monolayers on gold. Langmuir 1999, 15, 3529–3537.
Han, M. S.; Seong, S.; Han, S.; Lee, N. S.; Noh, J. Molecular self-assembly of phenylselenyl chloride on a Au (111) surface. Bull. Korean Chem. Soc. 2020, 41, 1048–1051.
Niebel, C; Calard, F.; Jarrosson, T.; Lère-Porte, J. P.; Breton, T.; Serein-Spirau, F. Spontaneous assembly of silylethane-thiol derivatives on Au (111): A chemically robust thiol protecting group as the precursor for the direct formation of aromatic gold thiolate monolayers. Chem. Commun. 2015, 51, 7622–7625.
Valkenier, H.; Huisman, E. H.; Van Hal, P. A.; De Leeuw, D. M.; Chiechi, R. C.; Hummelen, J. C. Formation of high-quality self-assembled monolayers of conjugated dithiols on gold: Base matters. J. Am. Chem. Soc. 2011, 133, 4930–4939.
Bashir, A.; Iqbal, D.; Jain, S. M.; Barbe, K.; Abu-Husein, T.; Rohwerder, M.; Terfort, A.; Zharnikov, M. Promoting effect of protecting group on the structure and morphology of self-assembled monolayers: Terphenylylethanethioactate on Au (111). J. Phys. Chem. C 2015, 119, 25352–25363.
Badin, M. G.; Bashir, A.; Krakert, S.; Strunskus, T.; Terfort, A.; Wöll, C. Kinetically stable, flat-lying thiolate monolayers. Angew. Chem., Int. Ed. 2007, 46, 3762–3764.
Park, T.; Kang, H. G.; Seong, S.; Han, S.; Son, Y. J.; Ito, E.; Hayashi, T.; Hara, M.; Noh, J. Formation and structure of highly ordered self-assembled monolayers by adsorption of acetyl-protected conjugated thiols on Au (111) in tetrabutylammonium cyanide solution. J. Phys. Chem. C 2019, 123, 9096–9104.
Ciszek, J. W.; Tour, J. M. Mechanistic implications of the assembly of organic thiocyanates on precious metals. Chem. Mater. 2005, 17, 5684–5690.
Lee, M. T.; Hsueh, C. C.; Freund, M. S.; Ferguson, G. S. Electrochemical self-assembly of monolayers from alkylthiosulfates on gold. Langmuir 2003, 19, 5246–5253.
Ossowski, J.; Nascimbeni, G.; Żaba, T.; Verwüster, E.; Rysz, J.; Terfort, A.; Zharnikov, M.; Zojer, E.; Cyganik, P. Relative thermal stability of thiolate- and selenolate-bonded aromatic monolayers on the Au (111) substrate. J. Phys. Chem. C 2017, 121, 28031–28042.
Wyczawska, S.; Cyganik, P.; Terfort, A.; Lievens, P. Ion-beam-induced desorption as a method for probing the stability of the molecule-substrate interface in self-assembled monolayers. ChemPhysChem 2011, 12, 2554–2557.
Füser, M. A.; Sauter, E.; Zharnikov, M.; Terfort, A. Synergism in bond strength modulation opens an alternative concept for protective groups in surface chemistry. J. Phys. Chem. C 2018, 122, 28839–28845.
Raiber, K.; Terfort, A.; Benndorf, C.; Krings, N.; Strehblow, H. H. Removal of self-assembled monolayers of alkanethiolates on gold by plasma cleaning. Surf. Sci. 2005, 595, 56–63.
Neese, F.; Wennmohs, F.; Becker, U.; Riplinger, C. The ORCA quantum chemistry program package. J. Chem. Phys. 2020, 152, 224108.
Perdew, J. P. Density-functional approximation for the correlation energy of the inhomogeneous electron gas. Phys. Rev. B 1986, 33, 8822–8824.
Becke, A. D. Density-functional exchange-energy approximation with correct asymptotic behavior. Phys. Rev. A 1988, 38, 3098–3100.
Weigend, F. Accurate Coulomb-fitting basis sets for H to Rn. Phys. Chem. Chem. Phys. 2006, 8, 1057–1065.
O’Byrne, A.; Murray, C.; Keegan, D.; Palacio, C.; Evans, P.; Morgan, B. S. The thio-adduct facilitated, enzymatic kinetic resolution of 4-hydroxycyclopentenone and 4-hydroxycyclohexenone. Org. Biomol. Chem. 2010, 8, 539–545.
Zeysing, B.; Gosch, C.; Terfort, A. Protecting groups for thiols suitable for Suzuki conditions. Org. Lett. 2000, 2, 1843–1845.
Nuzzo, R. G.; Korenic, E. M.; Dubois, L. H. Studies of the temperature-dependent phase behavior of long chain n-alkyl thiol monolayers on gold. J. Chem. Phys. 1990, 93, 767–773.
Azzam, W. Temperature-induced phase transition; polymorphism in BP2 SAMs on Au (111). Cent. Eur. J. Chem. 2009, 7, 884–899.
Pearce, H. A.; Sheppard, N. Possible importance of a “metal-surface selection rule” in the interpretation of the infrared spectra of molecules adsorbed on particulate metals; infrared spectra from ethylene chemisorbed on silica-supported metal catalysts. Surf. Sci. 1976, 59, 205–217.
Greenler, R. G. Infrared study of adsorbed molecules on metal surfaces by reflection techniques. J. Chem. Phys. 1966, 44, 310–315.
Gärtner, M.; Sauter, E.; Nascimbeni, G.; Petritz, A.; Wiesner, A.; Kind, M.; Abu-Husein, T.; Bolte, M.; Stadlober, B.; Zojer E. et al. Understanding the properties of tailor-made self-assembled monolayers with embedded dipole moments for interface engineering. J. Phys. Chem. C 2018, 122, 28757–28774.
Arnold, R.; Terfort, A.; Wöll, C. Determination of molecular orientation in self-assembled monolayers using IR absorption intensities: The importance of grinding effects. Langmuir 2001, 17, 4980–4989.
Abu-Husein, T.; Schuster, S.; Egger, D. A.; Kind, M.; Santowski, T.; Wiesner, A.; Chiechi, R.; Zojer, E.; Terfort, A.; Zharnikov, M. The effects of embedded dipoles in aromatic self-assembled monolayers. Adv. Funct. Mater. 2015, 25, 3943–3957.
Duan, L. L.; Garrett, S. J. An investigation of rigid p-methylterphenyl thiol self-assembled monolayers on Au (111) using reflection-absorption infrared spectroscopy and scanning tunneling microscopy. J. Phys. Chem. B 2001, 105, 9812–9816.
Shaporenko, A.; Elbing, M.; Błaszczyk, A.; Von Hänisch, C.; Mayor, M.; Zharnikov, M. Self-assembled monolayers from biphenyldithiol derivatives: Optimization of the deprotection procedure and effect of the molecular conformation. J. Phys. Chem. B 2006, 110, 4307–4317.
Azzam, W.; Bashir, A.; Biedermann, P. U.; Rohwerder, M. Formation of highly ordered and orientated gold islands: Effect of immersion time on the molecular adlayer structure of pentafluorobenzenethiols (PFBT) SAMs on Au (111). Langmuir 2012, 28, 10192–10208.
Bashir, A.; Azzam, W.; Rohwerder, M.; Terfort, A. Polymorphism in self-assembled terphenylthiolate monolayers on Au (111). Langmuir 2013, 29, 13449–13456.
Gärtner, M.; Sauter, E.; Nascimbeni, G.; Wiesner, A.; Kind, M.; Werner, P.; Schuch, C.; Abu-Husein, T.; Asyuda, A.; Bats, J. W. et al. Self-assembled monolayers with distributed dipole moments originating from bipyrimidine units. J. Phys. Chem. C 2020, 124, 504–519.
Cyganik, P.; Buck, M.; Wilton-Ely, J. D. E. T.; Wöll, C. Stress in self-assembled monolayers: ω-biphenyl alkane thiols on Au (111). J. Phys. Chem. B 2005, 109, 10902–10908.
Yang, G. H.; Liu, G. Y. New insights for self-assembled monolayers of organothiols on Au (111) revealed by scanning tunneling microscopy. J. Phys. Chem. B 2003, 107, 8746–8759.
Szelągowska-Kunstman, K.; Cyganik, P.; Schüpbach, B.; Terfort, A. Relative stability of thiol and selenol based SAMs on Au (111)-exchange experiments. Phys. Chem. Chem. Phys. 2010, 12, 4400–4406.
Gliboff, M.; Li, H; Knesting, K. M.; Giordano, A. J.; Nordlund, D.; Seidler, G. T.; Brédas, J. L.; Marder, S. R.; Ginger, D. S. Competing effects of fluorination on the orientation of aromatic and aliphatic phosphonic acid monolayers on indium Tin oxide. J. Phys. Chem. C 2013, 117, 15139–15147.
Barriet, D. Fluorinated self-assembled monolayers: Composition, structure and interfacial properties. Curr. Opin. Colloid Interface Sci. 2003, 8, 236–242.
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