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Chevalier RB, Pantano J, Kiesewetter MK, Dwyer JR. N-Heterocyclic carbene-based gold etchants. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2023; 14:865-871. [PMID: 37674545 PMCID: PMC10477970 DOI: 10.3762/bjnano.14.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023]
Abstract
N-Heterocyclic carbenes (NHCs) are an emerging alternative to thiols for the formation of stable self-assembled monolayers (SAMs) on gold. We examined several different species that have been used to produce NHC-based monolayers on gold, namely 1,3-diisopropyl-5-nitrobenzimidazolium iodide, 1,3-diisopropyl-5-nitrobenzimidazolium hydrogen carbonate, bis(1,3-diisopropyl-5-nitrobenzimidazolium)gold(I) iodide, and 1,3-diisopropyl-5-nitrobenzimidazole-2-ylidene. Contrary to expectation, solutions containing the first two species in tetrahydrofuran and dichloromethane caused visible loss of gold from thin-film-coated glass slides. The use of toluene solutions of all species resulted in no apparent dissolution of gold. We present scanning electron micrographs and elemental imaging analyses by energy dispersive X-ray spectroscopy to examine the effect of solutions of each species on the gold film. This work highlights the risk of unwanted etching during some routes to NHC-based surface functionalization but also the potential for deliberate etching, with the outcome determined by choice of chemically synthesized organic species and solvent.
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Affiliation(s)
- Robert B Chevalier
- Department of Chemistry, University of Rhode Island, 140 Flagg Road, Kingston, RI, 02881, USA
| | - Justin Pantano
- Department of Chemistry, University of Rhode Island, 140 Flagg Road, Kingston, RI, 02881, USA
| | - Matthew K Kiesewetter
- Department of Chemistry, University of Rhode Island, 140 Flagg Road, Kingston, RI, 02881, USA
| | - Jason R Dwyer
- Department of Chemistry, University of Rhode Island, 140 Flagg Road, Kingston, RI, 02881, USA
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2
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Jeong H, Kim D, Xiang D, Lee T. High-Yield Functional Molecular Electronic Devices. ACS NANO 2017; 11:6511-6548. [PMID: 28578582 DOI: 10.1021/acsnano.7b02967] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An ultimate goal of molecular electronics, which seeks to incorporate molecular components into electronic circuit units, is to generate functional molecular electronic devices using individual or ensemble molecules to fulfill the increasing technical demands of the miniaturization of traditional silicon-based electronics. This review article presents a summary of recent efforts to pursue this ultimate aim, covering the development of reliable device platforms for high-yield ensemble molecular junctions and their utilization in functional molecular electronic devices, in which distinctive electronic functionalities are observed due to the functional molecules. In addition, other aspects pertaining to the practical application of molecular devices such as manufacturing compatibility with existing complementary metal-oxide-semiconductor technology, their integration, and flexible device applications are also discussed. These advances may contribute to a deeper understanding of charge transport characteristics through functional molecular junctions and provide a desirable roadmap for future practical molecular electronics applications.
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Affiliation(s)
- Hyunhak Jeong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dongku Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dong Xiang
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
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3
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Lin L, Liu Z, Li X, Gu H, Ye J. Quantifying the reflective index of nanometer-thick thiolated molecular layers on nanoparticles. NANOSCALE 2017; 9:2213-2218. [PMID: 28120991 DOI: 10.1039/c6nr08501f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To precisely measure the refractive index (RI) of molecular layers is of great help to understand their fundamental optical properties and to develop advanced molecular layer-based devices including biosensors, photodetectors, and metamaterials. However, accurate quantification of the RI of ultra-thin nanometer-thick molecular layers immobilized on the surface of aqueous nanoparticles (NPs) remains a challenge. Here we have developed a method to quantify the effective RI of ultra-thin thiolated molecular layers with a thickness down to a sub-nanometer scale on the surface of plasmonic gold (Au) NPs. This method is realized by measuring and calculating the localized surface plasmon resonance (LSPR) shift of NPs due to the change of the surrounding RI and by quantifying the accurate molecular layer thickness via the TEM visualization of a nanogap junction in core-shell nanomatryoshka particles. The effective RI of the molecular layer is determined by fitting the experimental and calculated LSPR shifts using the least squares method. We have applied this method to quantify the effective RI of 1,4-benzenedithiol, 4,4'-biphenyldithiol, and 4,4'-terpheyldithiol molecules, proving their effectiveness and feasibility in ultra-thin molecular layers adsorbed on the NPs.
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Affiliation(s)
- Li Lin
- Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, P. R. China.
| | - Zhonghui Liu
- Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, P. R. China.
| | - Xiyao Li
- Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, P. R. China.
| | - Hongchen Gu
- Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, P. R. China.
| | - Jian Ye
- Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, P. R. China. and Shanghai Key Laboratory of Gynecologic Oncology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, P. R. China
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4
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Operamolla A, Punzi A, Farinola GM. Synthetic Routes to Thiol-Functionalized Organic Semiconductors for Molecular and Organic Electronics. ASIAN J ORG CHEM 2016. [DOI: 10.1002/ajoc.201600460] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alessandra Operamolla
- Dipartimento di Chimica; Università degli Studi di Bari Aldo Moro; Via Orabona 4 70126 Bari Italy
- CNR-ICCOM Istituto di Chimica dei Composti Organometallici; Via Orabona 4 70126 Bari Italy
| | - Angela Punzi
- Dipartimento di Chimica; Università degli Studi di Bari Aldo Moro; Via Orabona 4 70126 Bari Italy
| | - Gianluca M. Farinola
- Dipartimento di Chimica; Università degli Studi di Bari Aldo Moro; Via Orabona 4 70126 Bari Italy
- CNR-ICCOM Istituto di Chimica dei Composti Organometallici; Via Orabona 4 70126 Bari Italy
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5
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Jia J, Kara A, Pasquali L, Bendounan A, Sirotti F, Esaulov VA. On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study. J Chem Phys 2015; 143:104702. [PMID: 26374051 DOI: 10.1063/1.4929350] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S-C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.
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Affiliation(s)
- Juanjuan Jia
- Institut des Sciences Moléculaires d'Orsay, Université-Paris Sud, 91405 Orsay, France
| | - Abdelkader Kara
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Luca Pasquali
- Dipartimento di Ingegneria "E. Ferrari," Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena, Italy
| | - Azzedine Bendounan
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Fausto Sirotti
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Vladimir A Esaulov
- Institut des Sciences Moléculaires d'Orsay, Université-Paris Sud, 91405 Orsay, France
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6
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Hiszpanski AM, Lee SS, Wang H, Woll AR, Nuckolls C, Loo YL. Post-deposition processing methods to induce preferential orientation in contorted hexabenzocoronene thin films. ACS NANO 2013; 7:294-300. [PMID: 23228001 DOI: 10.1021/nn304003u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The structuring in organic electrically active thin films critically influences the performance of devices comprising them. Controlling film structure, however, remains challenging and generally requires stringent deposition conditions or modification of the substrate. To this end, we have developed post-deposition processing methods that are decoupled from the initial deposition conditions to induce different out-of-plane molecular orientations in contorted hexabenzocoronene (HBC) thin films. As-deposited HBC thin films lack any long-range order; subjecting them to post-deposition processing, such as hexanes-vapor annealing, thermal annealing, and physical contact with elastomeric poly(dimethyl siloxane), induces crystallization with increasing extents of preferential edge-on orientation, corresponding to greater degrees of in-plane π-stacking. Accordingly, transistors comprising HBC thin films that have been processed under these conditions exhibit field-effect mobilities that increase by as much as 2 orders of magnitude with increasing extents of molecular orientation. The ability to decouple HBC deposition from its subsequent structuring through post-deposition processing affords us the unique opportunity to tune competing molecule-molecule and molecule-solvent interactions, which ultimately leads to control over the structure and electrical function of HBC films.
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Affiliation(s)
- Anna M Hiszpanski
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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7
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Organic transistors with high thermal stability for medical applications. Nat Commun 2012; 3:723. [DOI: 10.1038/ncomms1721] [Citation(s) in RCA: 247] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 02/01/2012] [Indexed: 11/08/2022] Open
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8
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Valkenier H, Huisman EH, van Hal PA, de Leeuw DM, Chiechi RC, Hummelen JC. Formation of High-Quality Self-Assembled Monolayers of Conjugated Dithiols on Gold: Base Matters. J Am Chem Soc 2011; 133:4930-9. [DOI: 10.1021/ja110358t] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Paul A. van Hal
- Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands
| | - Dago M. de Leeuw
- Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands
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9
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Bruno G, Babudri F, Operamolla A, Bianco GV, Losurdo M, Giangregorio MM, Hassan Omar O, Mavelli F, Farinola GM, Capezzuto P, Naso F. Tailoring density and optical and thermal behavior of gold surfaces and nanoparticles exploiting aromatic dithiols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8430-8440. [PMID: 20433150 DOI: 10.1021/la101082t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Self-assembled monolayers (SAMs) derived of 4-methoxy-terphenyl-3'',5''-dimethanethiol (TPDMT) and 4-methoxyterphenyl-4''-methanethiol (TPMT) have been prepared by chemisorption from solution onto gold thin films and nanoparticles. The SAMs have been characterized by spectroscopic ellipsometry, Raman spectroscopy and atomic force microscopy to determine their optical properties, namely the refractive index and extinction coefficient, in an extended spectral range of 0.75-6.5 eV. From the analysis of the optical data, information on SAMs structural organization has been inferred. Comparison of SAMs generated from the above aromatic thiols to well-known SAMs generated from the alkanethiol dodecanethiol revealed that the former aromatic SAMs are densely packed and highly vertically oriented, with a slightly higher packing density and a absence of molecular inclination in TPMT/Au. The thermal behavior of SAMs has also been monitored using ellipsometry in the temperature range 25-500 degrees C. Gold nanoparticles functionalized by the same aromatic thiols have also been discussed for surface enhanced Raman spectroscopy applications. This study represents a step forward tailoring the optical and thermal behavior of surfaces as well as nanoparticles.
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Affiliation(s)
- Giovanni Bruno
- Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona 4, 70126 Bari, Italy.
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10
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Rajalingam K, Hallmann L, Strunskus T, Bashir A, Wöll C, Tuczek F. Self-assembled monolayers of benzylmercaptan and para-cyanobenzylmercaptan on gold: surface infrared spectroscopic characterization. Phys Chem Chem Phys 2010; 12:4390-9. [PMID: 20407711 DOI: 10.1039/b923628g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Self-assembled monolayers (SAMs) on gold substrates were prepared from benzylmercaptan (BM) and para-cyanobenzylmercaptan (pCBM), and the resulting surfaces were investigated using conventional infrared reflection-absorption spectroscopy (IRRAS) as well as polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). IRRAS data are analyzed by comparison with transmission IR spectra and theoretical (DFT) simulations. The spectroscopic results indicate the presence of well-ordered monolayers of BM and pCBM with an orientation perpendicular to the surface. IRRAS and PM-IRRAS data are compared to each other and the respective merits of both methods are discussed.
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Affiliation(s)
- K Rajalingam
- Institut für Anorganische Chemie, Christian-Albrechts Universität Kiel, Max-Eyth-Strasse 2, 24098 Kiel, Germany
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11
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Dulić D, Pump F, Campidelli S, Lavie P, Cuniberti G, Filoramo A. Controlled stability of molecular junctions. Angew Chem Int Ed Engl 2010; 48:8273-6. [PMID: 19728349 DOI: 10.1002/anie.200902168] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Diana Dulić
- CEA, Laboratoire d'Electronique Moléculaire, IRAMIS/SPEC, 91191 Gif sur Yvette cedex, France
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12
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Dulić D, Pump F, Campidelli S, Lavie P, Cuniberti G, Filoramo A. Controlled Stability of Molecular Junctions. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200902168] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Zakrassov A, Bitler A, Etgar L, Leitus G, Lifshitz E, Naaman R. Controlling the anisotropic magnetic dipolar interactions of PbSe self-assembled nanoparticles on GaAs. Phys Chem Chem Phys 2009; 11:7549-52. [DOI: 10.1039/b905341g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Barden WRT, Singh S, Kruse P. Roughening of gold atomic steps induced by interaction with tetrahydrofuran. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:2452-2458. [PMID: 18257587 DOI: 10.1021/la701757e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Exposure of a clean gold surface to tetrahydrofuran (THF) under ambient conditions was observed to cause roughening of atomic step edges. This change was followed in situ using a scanning tunneling microscope during the exposure of a gold surface to a controlled stream of THF vapor. THF is a common solvent used in depositing molecules, self-assembled monolayers, and polymer films on surfaces, in electrochemistry, and in chemical reactions. Unlike other solvents, such as methanol, ethanol and diethyl ether, however, we found that THF itself has a profound effect on the surface morphology that needs to be taken into account when reporting on the interactions of solutes with a gold surface. At the same time, this finding may present new opportunities in catalysis or nanostructuring of surfaces.
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Affiliation(s)
- Warren R T Barden
- Department of Chemistry, McMaster University, 1280 Main St. W., Hamilton, Ontario, L8S 4M1, Canada
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15
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Krapchetov DA, Ma H, Jen AKY, Fischer DA, Loo YL. Deprotecting thioacetyl-terminated terphenyldithiol for assembly on gallium arsenide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:851-856. [PMID: 18163654 DOI: 10.1021/la702430j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We characterize the assembly of terphenyldithiol (TPDT) on gallium arsenide (GaAs) from ethanol (EtOH) and tetrahydrofuran (THF) as a function of ammonium hydroxide (NH4OH) concentration. NH4OH facilitates the conversion of thioacetyl end groups of the TPDT precursor to thiolates in the assembly solution. The final structure of TPDT assembled on GaAs is sensitive not only to the assembly solvent but also to NH4OH concentration. In the presence of low concentrations of NH4OH (1 mM), TPDT assemblies from EtOH are oriented upright. The same assemblies are less upright when adsorption is carried out at higher NH4OH concentrations. In THF, TPDT does not adsorb significantly on GaAs at low NH4OH concentrations. The surface coverage and structural organization of these assemblies improve with increasing NH4OH concentrations, although these assemblies are never as organized as those from EtOH. The difference in the final structure of TPDT assemblies is attributed to differences in the thiolate fraction in the assembly solution at the point of substrate immersion.
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Affiliation(s)
- Dmitry A Krapchetov
- Chemical Engineering Department, University of Texas at Austin, Austin, Texas 78712, USA
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16
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Operamolla A, Hassan Omar O, Babudri F, Farinola GM, Naso F. Synthesis of S-Acetyl Oligoarylenedithiols via Suzuki−Miyaura Cross-Coupling. J Org Chem 2007; 72:10272-5. [DOI: 10.1021/jo701918z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alessandra Operamolla
- Dipartimento di Chimica, Università degli Studi di Bari, via Orabona, 4 I-70126 Bari, Italy, and Dipartimento di Chimica, CNR ICCOM-Dipartimento di Chimica, via Orabona, 4 I-70126 Bari, Italy
| | - Omar Hassan Omar
- Dipartimento di Chimica, Università degli Studi di Bari, via Orabona, 4 I-70126 Bari, Italy, and Dipartimento di Chimica, CNR ICCOM-Dipartimento di Chimica, via Orabona, 4 I-70126 Bari, Italy
| | - Francesco Babudri
- Dipartimento di Chimica, Università degli Studi di Bari, via Orabona, 4 I-70126 Bari, Italy, and Dipartimento di Chimica, CNR ICCOM-Dipartimento di Chimica, via Orabona, 4 I-70126 Bari, Italy
| | - Gianluca M. Farinola
- Dipartimento di Chimica, Università degli Studi di Bari, via Orabona, 4 I-70126 Bari, Italy, and Dipartimento di Chimica, CNR ICCOM-Dipartimento di Chimica, via Orabona, 4 I-70126 Bari, Italy
| | - Francesco Naso
- Dipartimento di Chimica, Università degli Studi di Bari, via Orabona, 4 I-70126 Bari, Italy, and Dipartimento di Chimica, CNR ICCOM-Dipartimento di Chimica, via Orabona, 4 I-70126 Bari, Italy
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17
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Zhou C, Walker AV. UV photooxidation and photopatterning of alkanethiolate self-assembled monolayers (SAMs) on GaAs (001). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8876-81. [PMID: 17628086 DOI: 10.1021/la7007864] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We have investigated the photooxidation of alkanethiolate self-assembled monoalyers (SAMs) adsorbed on GaAs (001) using time-of-flight secondary ion mass spectrometry. Both -CH3- and -COOH-terminated SAMs undergo photoreaction to form sulfonated species upon exposure to UV light from a 500 W Hg arc lamp (lambda = 280-440 nm) in the presence of oxygen. In contrast to SAMs adsorbed on metals, the photooxidation of octadecanethiol adsorbed on GaAs can be fit to two first-order reactions: a fast initial reaction followed by a second slower reaction ( approximately 6 times slower). For SAMs with shorter alkyl chain lengths, the photooxidation process is can be fit to a single first-order reaction. Using the optimal photooxidation time, we also demonstrate that SAMs can be successfully UV photopatterned on GaAs substrates producing sharp, well-defined patterns.
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Affiliation(s)
- Chuanzhen Zhou
- Department of Chemistry and Center for Materials Innovation, Washington University in St. Louis, Campus Box 1134, One Brooking Drive, St. Louis, Missouri 63130, USA
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18
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McGuiness CL, Blasini D, Masejewski JP, Uppili S, Cabarcos OM, Smilgies D, Allara DL. Molecular self-assembly at bare semiconductor surfaces: characterization of a homologous series of n-alkanethiolate monolayers on GaAs(001). ACS NANO 2007; 1:30-49. [PMID: 19203128 DOI: 10.1021/nn7000596] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Structural trends for a homologous series of n-alkanethiolate self-assembled monolayers (SAMs), C(n)H(2n+1)S- with 12 < or = n < or = 19, on GaAs(001), studied by a combination of grazing incidence X-ray diffraction and infrared spectroscopy, along with ancillary probes, show an overall decay in organization with decreasing n, with the largest changes occurring below n = 15-16. The long-chain monolayers form a mosaic structure with < or =10 nm domains of molecules organized in an incommensurate pseudo-hcp arrangement with nearest neighbor distances of 4.70 and 5.02 A, a 21.2 A(2) area per chain, two chains per subcell in a herringbone packing with a chain tilt angle of 14 degrees , and preferential domain alignment along the substrate [110]([110]) step edge direction. In contrast, for n < 14 no evidence of translational ordering is seen and the alkyl chains exhibit a loss of conformational ordering and coverage relative to the n > 16 cases. A 4'-methyl-biphenyl-4-thiolate companion SAM shows evidence for ordered structures but with lattice parameters close to those expected for a structure commensurate with the intrinsic GaAs(001) square lattice. These trends are explained on the basis of competitions between lattice, interfacial, and intermolecular forces controlling the nanoscale structures of the SAMs. Overall these results provide an important aspect of understanding the effects of SAM formation on surface properties such as electronic and chemical passivation.
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Affiliation(s)
- Christine L McGuiness
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16801-6300, USA
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19
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Badin M, Bashir A, Krakert S, Strunskus T, Terfort A, Wöll C. Kinetisch stabile, flach liegende Thiolat-Monoschichten. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200605125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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20
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Badin MG, Bashir A, Krakert S, Strunskus T, Terfort A, Wöll C. Kinetically Stable, Flat-Lying Thiolate Monolayers. Angew Chem Int Ed Engl 2007; 46:3762-4. [PMID: 17415727 DOI: 10.1002/anie.200605125] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mihaela G Badin
- Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, 44780 Bochum, Germany
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21
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Haran M, Goose JE, Clote NP, Clancy P. Multiscale modeling of self-assembled monolayers of thiophenes on electronic material surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:4897-909. [PMID: 17397195 DOI: 10.1021/la063059d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Computer simulation programs, spanning different time and length scales, are used to describe the fundamentals of thin film growth morphology in organic self-assembled monolayers using thiophenes on gold as representative systems. Ab initio calculations created a catalog of the energetics between two N-[4-(thien-2ylethynyl)phenyl] hydroxyl ("1P" molecules) in vacuum and interactions in three orthogonal orientations (parallel, perpendicular, and gamma-phase) to a Au (111) surface. This energetic dataset was supplied as the input for kinetic Monte Carlo simulations of dimer and trimer representations of small organic molecules to describe both sub-monolayer and multilayer growth on a series of hypothetical model substrates. On strongly binding metallic-like substrates, sub-monolayers of the model organic molecules formed ordered phases in the x and y directions at high temperatures and a disordered polycrystalline structure at low temperatures with the molecules lying down. Only at high temperatures was a "phase inversion" observed from a completely flat to an upright structure, suggesting the upright phase to be kinetically limited. Results for multilayer deposition of 1P molecules on three substrates which differ in their binding energy to the molecule (from non-interacting to strongly binding substrates) provided a rich view of the polymorphism that can result from differing choices of temperature and flux conditions. Irrespective of the binding energy of the molecule to the substrate, on highly corrugated surfaces we always observed 3D-island growth of multiple layers of the thiophenes, in contrast to Stranski-Krastanov or Frank-van der Merwe growth on more uniform substrates. The qualitative picture we obtained agrees with the growth habits of other small organic molecule systems like the acene series. Finally, molecular dynamics studies were used to understand the packing structures of stable polymorphs of thiophene SAMs. Different deposition conditions and substrate-molecule binding captured different regimes of growth morphology, some of which have already been observed experimentally.
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Affiliation(s)
- Mohit Haran
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
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Loo YL(L. Solution-processable organic semiconductors for thin-film transistors: Opportunities for chemical engineers. AIChE J 2007. [DOI: 10.1002/aic.11151] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Krapchetov DA, Ma H, Jen AKY, Fischer DA, Loo YL. High-sensitivity transmission IR spectroscopy for the chemical identification and structural analysis of conjugated molecules on gallium arsenide surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9491-4. [PMID: 17073469 DOI: 10.1021/la0623984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We demonstrate the use of high-sensitivity, off-normal transmission IR spectroscopy with s-polarized light to probe the chemical identity and orientation of quaterphenyldithiol (QPDT) molecular assemblies on GaAs as a function of ammonium hydroxide (NH4OH) concentration. NH4OH is added to the assembly solution to convert the thioacetyl groups on the QPDT precursor to thiolates. When assembled at high NH4OH concentrations, the acetyl groups are completely removed, and QPDT is disordered on GaAs. Assembly at low NH4OH concentrations, however, results in QPDT assemblies that are preferentially upright. The molecular orientation is further quantified with near-edge X-ray absorption fine structure spectroscopy.
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Affiliation(s)
- Dmitry A Krapchetov
- Chemical Engineering Department and Center for Nano- and Molecular Science and Technology, University of Texas at Austin, Austin, Texas 78712, USA
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Genzer J, Efimenko K, Fischer DA. Formation mechanisms and properties of semifluorinated molecular gradients on silica surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:8532-41. [PMID: 16981773 DOI: 10.1021/la061016r] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The goal of this study is to elucidate the formation of molecular gradients made of semifluorinated organosilanes (SFOs) on flat substrates by using a methodology developed by Chaudhury and Whitesides (Science 1992, 256, 1539). We use surface-sensitive combinatorial near-edge X-ray absorption fine structure (combi-NEXAFS) spectroscopy to measure the position-dependent concentration and orientation of SFO molecules in SFO molecular gradients on flat silica surfaces. Using the combi-NEXAFS data, we establish the correlation between the fraction of the F(CF(2))(8)(CH(2))(2)- species on the substrate and the average tilt angle of the -(CF(2))(8)F group in the SFO as a function of the deposition gas medium (air vs nitrogen) and the end group around the silicon atom (monofunctional vs trifunctional). In addition, we utilize the gradient geometry to comprehend the mechanism of formation of SFO self-assembled monolayers (SAMs). Specifically, we provide evidence that depending on the nature of the end group in the SFO and the vapor phase the SFO molecules add themselves into the existing SAMs either as individual molecules or as multimolecular complexes.
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Affiliation(s)
- Jan Genzer
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA. Jan_Genzer@ ncsu.edu
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Zin MT, Yip HL, Wong NY, Ma H, Jen AKY. Arrays of covalently bonded single gold nanoparticles on thiolated molecular assemblies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:6346-51. [PMID: 16800697 DOI: 10.1021/la053256x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A simple approach to form arrays of covalently bonded single gold nanoparticles (AuNPs) is demonstrated. Asymmetric molecular assemblies composed of two layers of rigid aromatic molecules with different structures, arranged in hexagonal arrays on a template produced by edge-spreading lithography, are used to guide the assembly of AuNPs. Arrays of single AuNPs are achieved by taking advantage of the interplay of electrostatic interactions and covalent bonding in conjunction with the positional constraint on the template. Schiff base chemistry is highlighted in the surface chemical reaction to selectively modify nanoscale surface features with high yield.
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Affiliation(s)
- Melvin T Zin
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195-2120, USA
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26
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Jun Y, Zhu XY, Hsu JWP. Formation of alkanethiol and alkanedithiol monolayers on GaAs(001). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:3627-32. [PMID: 16584236 DOI: 10.1021/la052473v] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The formation of alkanethiol (H-(CH2)n-SH, n = 8-18) and 1,8-octanedithiol (HS-(CH2)8-SH) monolayer films on n-type GaAs(001) has been systematically studied. We observed a nonlinear dependence of the film thickness on molecular length, which is drastically different from monolayer films of the same molecules on metals. For 8 < or = n < or = 14, the films are only 3-4.5 A thick, significantly smaller than the corresponding molecular length. For n = 16 and 18, the measured film thicknesses were 9 and 11 A, respectively, consistent with molecules orienting with a tilt angle of approximately 60 degrees from the surface normal. Unlike the alkanethiols, the thickness of the 1,8-octanedithiol monolayer is almost the same as its molecular length, indicating that dithiol molecules orient vertically with only one thiol end group bound to the GaAs surface. Additional support for this conclusion comes from the fact that X-ray photoelectron spectroscopy of the 1,8-octanedithiol monolayer clearly resolves two types of S atoms in the monolayer: those bound to the GaAs surface and those existing as free thiols. A suggestion was made on the mechanisms for alkanethiol and alkanedithiol monolayer formation.
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Affiliation(s)
- Yongseok Jun
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Shao X, Luo X, Hu X, Wu K. Solvent Effect on Self-Assembled Structures of 3,8-Bis-hexadecyloxy-benzo[c]cinnoline on Highly Oriented Pyrolytic Graphite. J Phys Chem B 2005; 110:1288-93. [PMID: 16471676 DOI: 10.1021/jp055910n] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
3,8-Bis-hexadecyloxy-benzo[c]cinnoline (BBC16) self-assembled into two structures at highly oriented pyrolytic graphite (HOPG) surface: one was formed by molecules with a V-like configuration (C2v symmetry) and the other by molecules with a Z-like configuration (C(s) symmetry). The self-assembled structures could be tweaked by the solvents used. In the self-assembled monolayers (SAMs) on HOPG, the BBC16 molecule adopted the V-like configuration in polar solvents and the Z-like configuration in nonpolar solvents. Moreover, the solvent viscosity, solvent dissolvability of BBC16, and substrate temperature also played some roles in tuning the two-dimensional self-assembled structures.
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Affiliation(s)
- Xiang Shao
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Physical Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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