1
|
Wu A, Fan Y, Tao C, Chen X, Dappe YJ, Du J, Zhang Q. Molecular Diodes Induced by a Schottky Barrier with a Gold-Silicon Doped Electrode. J Phys Chem Lett 2024; 15:7011-7019. [PMID: 38949616 DOI: 10.1021/acs.jpclett.4c01351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
To create complementary metal oxide semiconductor compatible molecular devices, more insights into the electrode property regarding its metal/semiconductor doping level and creating a functional molecular device are required. In this work, we constructed an EGaIn/alkanethiol/Au-Si molecular diode (with a rectification ratio R of 50.70) induced by Schottky barriers within a gold-silicon doped electrode instead of the functional property of molecules. The relationship between the rectification ratio and the number of methylene units in alkanethiol was analyzed, revealing a gradual increase in the ratio from 3.33 for C6H14S to 50.70 for C16H34S. The rectification ratio of the junction is well modulated by the temperature due to the change in the Schottky barrier. Such a mechanism is explained by the energy band diagrams of the surface space charge region and a combination of density functional theory and Keldysh-Green formalism calculations.
Collapse
Affiliation(s)
- An Wu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Yidan Fan
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Changyuan Tao
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Xiaoping Chen
- College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000, China
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette Cedex 91191, France
| | - Jun Du
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Qian Zhang
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| |
Collapse
|
2
|
Li M, Jiang Y, Ju H, He S, Jia C, Guo X. Electronic Devices Based on Heterostructures of 2D Materials and Self-Assembled Monolayers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2402857. [PMID: 38934535 DOI: 10.1002/smll.202402857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/11/2024] [Indexed: 06/28/2024]
Abstract
2D materials (2DMs), known for their atomically ultrathin structure, exhibit remarkable electrical and optical properties. Similarly, molecular self-assembled monolayers (SAMs) with comparable atomic thickness show an abundance of designable structures and properties. The strategy of constructing electronic devices through unique heterostructures formed by van der Waals assembly between 2DMs and molecular SAMs not only enables device miniaturization, but also allows for convenient adjustment of their structures and functions. In this review, the fundamental structures and fabrication methods of three different types of electronic devices dominated by 2DM-SAM heterojunctions with varying architectures are timely elaborated. Based on these heterojunctions, their fundamental functionalities and characteristics, as well as the regulation of their performance by external stimuli, are further discussed.
Collapse
Affiliation(s)
- Mengmeng Li
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
| | - Yu Jiang
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
| | - Hongyu Ju
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, 300072, P. R. China
| | - Suhang He
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
| | - Chuancheng Jia
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
| | - Xuefeng Guo
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, P. R. China
- Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| |
Collapse
|
3
|
Hight MO, Wong JY, Pimentel AE, Su TA. Intramolecular London Dispersion Interactions in Single-Molecule Junctions. J Am Chem Soc 2024; 146:4716-4726. [PMID: 38325000 PMCID: PMC10885141 DOI: 10.1021/jacs.3c12183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
This work shows the first example of using intramolecular London dispersion interactions to control molecular geometry and quantum transport in single-molecule junctions. Flexible σ-bonded molecular junctions typically occupy straight-chain geometries due to steric effects. Here, we synthesize a series of thiomethyl-terminated oligo(dimethylsilmethylene)s that bear [CH2-Si(CH3)2]n repeat units, where all backbone dihedral states are sterically equivalent. Scanning tunneling microscopy break-junction (STM-BJ) measurements and theoretical calculations indicate that in the absence of a strong steric bias concerted intramolecular London dispersion interactions staple the carbosilane backbone into coiled conformations that remain intact even as the junction is stretched to its breakpoint. As these kinked conformations are highly resistive to electronic transport, we observe record-high conductance decay values on an experimental junction length basis (β = 1.86 ± 0.12 Å-1). These studies reveal the potential of using intramolecular London dispersion interactions to design single-molecule electronics.
Collapse
Affiliation(s)
- Matthew O Hight
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Joshua Y Wong
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Ashley E Pimentel
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Timothy A Su
- Department of Chemistry, University of California, Riverside, California 92521, United States
- Materials Science & Engineering Program, University of California, Riverside, California 92521, United States
| |
Collapse
|
4
|
Xiong Z, Zhang J, Sun JZ, Zhang H, Tang BZ. Excited-State Odd-Even Effect in Through-Space Interactions. J Am Chem Soc 2023; 145:21104-21113. [PMID: 37715315 DOI: 10.1021/jacs.3c08164] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
The odd-even effect is a fantastic phenomenon in nature, which has been applied in diverse fields such as organic self-assembled monolayers and liquid crystals. Currently, the origin of each odd-even effect remains elusive, and all of the reported odd-even effects are related to the ground-state properties. Here, we discover an excited-state odd-even effect in the through-space interaction (TSI) of nonconjugated tetraphenylalkanes (TPAs). The TPAs with an even number of alkyl carbon atoms (C2-TPA, C4-TPA, and C6-TPA) show strong TSI, long-wavelength emission, and high QY. However, the odd ones (C1-TPA, C3-TPA, C5-TPA, and C7-TPA) are almost nonexistent with negligible QY. Systematically experimental and theoretical results reveal that the excited-state odd-even effect is synthetically determined by three factors: alkyl geometry, molecular movability, and intermolecular packing. Moreover, these flexible luminescent TPAs possess tremendous advantages in fluorescent information encryptions. This work extends the odd-even effect to photophysics, demonstrating its substantial importance and universality in nature.
Collapse
Affiliation(s)
- Zuping Xiong
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, China
- Centre of Healthcare Materials, Shaoxing Institute, Zhejiang University, Shaoxing 312000, China
| | - Jianyu Zhang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong 999077, China
| | - Jing Zhi Sun
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
- Centre of Healthcare Materials, Shaoxing Institute, Zhejiang University, Shaoxing 312000, China
| | - Haoke Zhang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, China
- Centre of Healthcare Materials, Shaoxing Institute, Zhejiang University, Shaoxing 312000, China
| | - Ben Zhong Tang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong 999077, China
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), Guangzhou 518172, China
| |
Collapse
|
5
|
Park S, Kim E, Choi Y, Jang J, Kwak K, Cho M, Yoon HJ. Thermoresponse of Odd-Even Effect in n-Alkanethiolate Self-Assembled Monolayers on Gold Substrates. Chemistry 2023; 29:e202203536. [PMID: 36548089 DOI: 10.1002/chem.202203536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/22/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022]
Abstract
This study examines thermoresponse of odd-even effect in self-assembled monolayers (SAMs) of n-alkanethiolates (SCn , n=3-18) formed on template-stripped gold (AuTS ) using macro- and microscopic analytical techniques, contact angle goniometry (CAG) and vibrational sum frequency generation (VSFG) spectroscopy, respectively. Both CAG and VSFG analyses showed that the odd-even effect in liquid-like SAMs (n=3-9) disappeared upon heating at 50-70 °C, indicating that the heating led to increased structural disorder regardless of odd and even carbon numbers. In contrast, the opposite thermoresponse was observed for odd and even SCn molecules in wax- and solid-like SAMs (n=10-18). Namely, temperature-dependent orientational change of terminal CH3 relative to the surface normal was opposite for the odd and even molecules, thereby leading to mitigated odd-even effect. Our work offers important insights into thermoresponse of supramolecular structure in condensed organic matter.
Collapse
Affiliation(s)
- Sohyun Park
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Eunchan Kim
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.,Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul, 02841, Republic of Korea
| | - Youngjin Choi
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.,Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul, 02841, Republic of Korea
| | - Jiung Jang
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Kyungwon Kwak
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.,Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul, 02841, Republic of Korea
| | - Minhaeng Cho
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.,Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul, 02841, Republic of Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| |
Collapse
|
6
|
Zhao Z, Soni S, Lee T, Nijhuis CA, Xiang D. Smart Eutectic Gallium-Indium: From Properties to Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2203391. [PMID: 36036771 DOI: 10.1002/adma.202203391] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/30/2022] [Indexed: 05/27/2023]
Abstract
Eutectic gallium-indium (EGaIn), a liquid metal with a melting point close to or below room temperature, has attracted extensive attention in recent years due to its excellent properties such as fluidity, high conductivity, thermal conductivity, stretchability, self-healing capability, biocompatibility, and recyclability. These features of EGaIn can be adjusted by changing the experimental condition, and various composite materials with extended properties can be further obtained by mixing EGaIn with other materials. In this review, not only the are unique properties of EGaIn introduced, but also the working principles for the EGaIn-based devices are illustrated and the developments of EGaIn-related techniques are summarized. The applications of EGaIn in various fields, such as flexible electronics (sensors, antennas, electronic circuits), molecular electronics (molecular memory, opto-electronic switches, or reconfigurable junctions), energy catalysis (heat management, motors, generators, batteries), biomedical science (drug delivery, tumor therapy, bioimaging and neural interfaces) are reviewed. Finally, a critical discussion of the main challenges for the development of EGaIn-based techniques are discussed, and the potential applications in new fields are prospected.
Collapse
Affiliation(s)
- Zhibin Zhao
- Institute of Modern Optics and Center of Single Molecule Sciences, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, 300350, Tianjin, P. R. China
| | - Saurabh Soni
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands
| | - Takhee Lee
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Christian A Nijhuis
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands
| | - Dong Xiang
- Institute of Modern Optics and Center of Single Molecule Sciences, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, 300350, Tianjin, P. R. China
| |
Collapse
|
7
|
Karuppannan SK, Nijhuis CA. A Method to Investigate the Mechanism of Charge Transport Across Bio-Molecular Junctions with Ferritin. Methods Mol Biol 2023; 2671:241-255. [PMID: 37308649 DOI: 10.1007/978-1-0716-3222-2_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To investigate the mechanisms of charge transport (CT) across biomolecular tunnel junctions, it is required to make electrical contacts by a non-invasive method that leaves the biomolecules unaltered. Although different methods to form biomolecular junctions are available, here we describe the EGaIn-method because it allows us to readily form electrical contacts to monolayers of biomolecules in ordinary laboratory settings and to probe CT as a function of voltage, temperature, or magnetic field. This method relies on a non-Newtonian liquid-metal ally of Ga and In with a few nm thin layer of GaOx floating on its surface giving this material non-Newtonian properties allowing it to be shaped in to cone-shaped tips or stabilized in microchannels. These EGaIn structures form stable contacts to monolayers making it possible to investigate CT mechanisms across biomolecules in great detail.
Collapse
Affiliation(s)
- Senthil Kumar Karuppannan
- National Quantum Fables Foundry (NQFF), Institute of Materials Research and Engineering, Singapore, Singapore
| | - Christian A Nijhuis
- Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands.
| |
Collapse
|
8
|
Estimating the Number of Molecules in Molecular Junctions Merely Based on the Low Bias Tunneling Conductance at Variable Temperature. Int J Mol Sci 2022; 23:ijms232314985. [PMID: 36499309 PMCID: PMC9737784 DOI: 10.3390/ijms232314985] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022] Open
Abstract
Temperature (T) dependent conductance G=G(T) data measured in molecular junctions are routinely taken as evidence for a two-step hopping mechanism. The present paper emphasizes that this is not necessarily the case. A curve of lnG versus 1/T decreasing almost linearly (Arrhenius-like regime) and eventually switching to a nearly horizontal plateau (Sommerfeld regime), or possessing a slope gradually decreasing with increasing 1/T is fully compatible with a single-step tunneling mechanism. The results for the dependence of G on T presented include both analytical exact and accurate approximate formulas and numerical simulations. These theoretical results are general, also in the sense that they are not limited, e.g., to the (single molecule electromigrated (SET) or large area EGaIn) fabrication platforms, which are chosen for exemplification merely in view of the available experimental data needed for analysis. To be specific, we examine in detail transport measurements for molecular junctions based on ferrocene (Fc). As a particularly important finding, we show how the present analytic formulas for G=G(T) can be utilized to compute the ratio f=Aeff/An between the effective and nominal areas of large area Fc-based junctions with an EGaIn top electrode. Our estimate of f≈0.6×10-4 is comparable with previously reported values based on completely different methods for related large area molecular junctions.
Collapse
|
9
|
Soh EJH, Astier HPAG, Daniel D, Isaiah Chua JQ, Miserez A, Jia Z, Li L, O'Shea SJ, Bhaskaran H, Tomczak N, Nijhuis CA. AFM Manipulation of EGaIn Microdroplets to Generate Controlled, On-Demand Contacts on Molecular Self-Assembled Monolayers. ACS NANO 2022; 16:14370-14378. [PMID: 36065994 DOI: 10.1021/acsnano.2c04667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid metal droplets, such as eutectic gallium-indium (EGaIn), are important in many research areas, such as soft electronics, catalysis, and energy storage. Droplet contact on solid surfaces is typically achieved without control over the applied force and without optimizing the wetting properties in different environments (e.g., in air or liquid), resulting in poorly defined contact areas. In this work, we demonstrate the direct manipulation of EGaIn microdroplets using an atomic force microscope (AFM) to generate repeated, on-demand making and breaking of contact on self-assembled monolayers (SAMs) of alkanethiols. The nanoscale positional control and feedback loop in an AFM allow us to control the contact force at the nanonewton level and, consequently, tune the droplet contact areas at the micrometer length scale in both air and ethanol. When submerged in ethanol, the droplets are highly nonwetting, resulting in hysteresis-free contact forces and minimal adhesion; as a result, we are able to create reproducible geometric contact areas of 0.8-4.5 μm2 with the alkanethiolate SAMs in ethanol. In contrast, there is a larger hysteresis in the contact forces and larger adhesion for the same EGaIn droplet in air, which reduced the control over the contact area (4-12 μm2). We demonstrate the usefulness of the technique and of the gained insights in EGaIn contact mechanics by making well-defined molecular tunneling junctions based on alkanethiolate SAMs with small geometric contact areas of between 4 and 12 μm2 in air, 1 to 2 orders of magnitude smaller than previously achieved.
Collapse
Affiliation(s)
- Eugene Jia Hao Soh
- Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634
| | | | - Dan Daniel
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634
- Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Jia Qing Isaiah Chua
- Biological and Biomimetic Material Laboratory, Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553
| | - Ali Miserez
- Biological and Biomimetic Material Laboratory, Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553
| | - Zian Jia
- Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Ling Li
- Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Sean J O'Shea
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634
| | - Harish Bhaskaran
- Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom
| | - Nikodem Tomczak
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore, Singapore 117543
- Hybrid Materials for Optoelectronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands
| |
Collapse
|
10
|
Influence of Aliphatic Chain Length on Structural, Thermal and Electrochemical Properties of n-alkylene Benzyl Alcohols: A Study of the Odd-Even Effect. Molecules 2022; 27:molecules27123781. [PMID: 35744908 PMCID: PMC9229344 DOI: 10.3390/molecules27123781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 02/01/2023] Open
Abstract
The century-old, well-known odd–even effect phenomenon is still a very attractive and intriguing topic in supramolecular and nano-scale organic chemistry. As a part of our continuous efforts in the study of supramolecular chemistry, we have prepared three novel aromatic alcohols (1,2-bis[2-(hydroxymethyl)phenoxy]butylene (Do4OH), 1,2-bis[2-(hydroxymethyl)phenoxy]pentylene (Do5OH) and 1,2-bis[2-(hydroxymethyl)phenoxy]hexylene (Do6OH)) and determined their crystal and molecular structures by single-crystal X-ray diffraction. In all compounds, two benzyl alcohol groups are linked by an aliphatic chain of different lengths (CH2)n; n = 4, 5 and 6. The major differences in the molecular structures were found in the overall planarity of the molecules and the conformation of the aliphatic chain. Molecules with an even number of CH2 groups tend to be planar with an all-trans conformation of the aliphatic chain, while the odd-numbered molecule is non-planar, with partial gauche conformation. A direct consequence of these structural differences is visible in the melting points—odd-numbered compounds of a particular series display systematically lower melting points. Crystal and molecular structures were additionally studied by the theoretical calculations and the melting points were correlated with packing density and the number of CH2 groups. The results have shown that the generally accepted rule, higher density = higher stability = higher melting point, could not be applied to these compounds. It was found that the denser packaging causes an increase in the percentage of repulsive H‧‧‧H interactions, thereby reducing the stability of the crystal, and consequently, the melting points. Another interesting consequence of different molecular structures is their electrochemical and antioxidative properties—a non-planar structure displays the highest oxidation peak of hydroxyl groups and moderate antioxidant activity.
Collapse
|
11
|
Shi J, Jiang F, Long S, Lu Z, Liu T, Zheng H, Shi J, Yang Y, Hong W, Tian ZQ. The influence of water on the charge transport through self-assembled monolayers junctions fabricated by EGaIn technique. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.139304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
12
|
Xie Z, Bâldea I, Nguyen QV, Frisbie CD. Quantitative analysis of weak current rectification in molecular tunnel junctions subject to mechanical deformation reveals two different rectification mechanisms for oligophenylene thiols versus alkane thiols. NANOSCALE 2021; 13:16755-16768. [PMID: 34604892 DOI: 10.1039/d1nr04410a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Metal-molecule-metal junctions based on alkane thiol (CnT) and oligophenylene thiol (OPTn) self-assembled monolayers (SAMs) and Au electrodes are expected to exhibit similar electrical asymmetry, as both junctions have one chemisorbed Au-S contact and one physisorbed, van der Waals contact. Asymmetry is quantified by the current rectification ratio RR apparent in the current-voltage (I-V) characteristics. Here we show that RR < 1 for CnT and RR > 1 for OPTn junctions, in contrast to expectation, and further, that RR behaves very differently for CnT and OPTn junctions under mechanical extension using the conducting probe atomic force microscopy (CP-AFM) testbed. The analysis presented in this paper, which leverages results from the previously validated single level model and ab initio quantum chemical calculations, allows us to explain the puzzling experimental findings for CnT and OPTn in terms of different current rectification mechanisms. Specifically, in CnT-based junctions the Stark effect creates the HOMO level shifting necessary for rectification, while for OPTn junctions the level shift arises from position-dependent coupling of the HOMO wavefunction with the junction electrostatic potential profile. On the basis of these mechanisms, our quantum chemical calculations allow quantitative description of the impact of mechanical deformation on the measured current rectification. Additionally, our analysis, matched to experiment, facilitates direct estimation of the impact of intramolecular electrostatic screening on the junction potential profile. Overall, our examination of current rectification in benchmark molecular tunnel junctions illuminates key physical mechanisms at play in single step tunneling through molecules, and demonstrates the quantitative agreement that can be obtained between experiment and theory in these systems.
Collapse
Affiliation(s)
- Zuoti Xie
- Department of Materials Science and Engineering, Guangdong Technion-Israel Institute of Technology, Shantou, Guangdong, 515063, China.
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
| | - Ioan Bâldea
- Theoretical Chemistry, Heidelberg University, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
| | - Quyen Van Nguyen
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
| |
Collapse
|
13
|
Sand AM, Malme JT, Hoy EP. A multiconfiguration pair-density functional theory-based approach to molecular junctions. J Chem Phys 2021; 155:114115. [PMID: 34551556 DOI: 10.1063/5.0063293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Due to their small size and unique properties, single-molecule electronics have long seen research interest from experimentalists and theoreticians alike. From a theoretical standpoint, modeling these systems using electronic structure theory can be difficult due to the importance of electron correlation in the determination of molecular properties, and this electron correlation can be computationally expensive to consider, particularly multiconfigurational correlation energy. In this work, we develop a new approach for the study of single-molecule electronic systems, denoted NEGF-MCPDFT, which combines multiconfiguration pair-density functional theory (MCPDFT) with the non-equilibrium Green's function formalism (NEGF). The use of MCPDFT with NEGF allows for the efficient inclusion of both static and dynamic electron correlations in the description of the junction's electronic structure. Complete active space self-consistent field wave functions are used as references in the MCPDFT calculation, and as with any active space method, effort must be made to determine the proper orbital character to include in the active space. We perform conductance and transmission calculations on a series of alkanes (predominantly single-configurational character) and benzyne (multiconfigurational character), exploring the role that active space selection has on the computed results. For the alkane junctions explored (where dynamic electron correlation dominates), the MCPDFT-NEGF results agree well with the DFT-NEGF results. For the benzyne junction (which has a significant static correlation), we see clear differences in the MCPDFT-NEGF and DFT-NEGF results and evidence that NEGF-MCPDFT is capturing additional electron correlation effects beyond those provided by the Perdew-Burke-Ernzerhof functional.
Collapse
Affiliation(s)
- Andrew M Sand
- Department of Chemistry and Biochemistry, Butler University, Indianapolis, Indiana 46208, USA
| | - Justin T Malme
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, New Jersey 08028, USA
| | - Erik P Hoy
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, New Jersey 08028, USA
| |
Collapse
|
14
|
Cheng HW, Yan S, Shang G, Wang S, Zhong CJ. Strain sensors fabricated by surface assembly of nanoparticles. Biosens Bioelectron 2021; 186:113268. [PMID: 33971524 DOI: 10.1016/j.bios.2021.113268] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/05/2021] [Accepted: 04/16/2021] [Indexed: 01/02/2023]
Abstract
Harnessing interparticle spatial properties of surface assembly of nanoparticles (SAN) on flexible substrates is a rapidly emerging front of research in the design and fabrication of highly-sensitive strain sensors. It has recently shown promising potentials for applications in wearable sensors and skin electronics. SANs feature 3D structural tunability of the interparticle spatial properties at both molecular and nanoscale levels, which is transformative for the design of intriguing strain sensors. This review will present a comprehensive overview of the recent research development in exploring SAN-structured strain sensors for wearable applications. It starts from the basic principle governing the strain sensing characteristics of SANs on flexible substrates in terms of thermally-activated interparticle electron tunneling and conductive percolation. This discussion is followed by descriptions of the fabrication of the sensors and the proof-of-concept demonstrations of the strain sensing characteristics. The nanoparticles in the SANs are controllable in terms of size, shape, and composition, whereas the interparticle molecules enable the tunability of the electrical properties in terms of interparticle spatial properties. The design of SAN-derived strain sensors is further highlighted by describing several recent examples in the explorations of their applications in wearable biosensor and bioelectronics. Fundamental understanding of the role of interparticle spatial properties within SANs at both molecular and device levels is the focal point. The future direction of the SAN-derived wearable sensors will also be discussed, shining lights on a potential paradigm shift in materials design in exploring the emerging opportunities in wearable sensors and skin electronics.
Collapse
Affiliation(s)
- Han-Wen Cheng
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, 201418, China; Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, 13902, USA.
| | - Shan Yan
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, 13902, USA
| | - Guojun Shang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, 13902, USA
| | - Shan Wang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, 13902, USA
| | - Chuan-Jian Zhong
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, 13902, USA.
| |
Collapse
|
15
|
Electrochemical and surface enhanced infrared absorption spectroscopy studies of TEMPO self-assembled monolayers. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
16
|
Ben Amara F, Dionne ER, Kassir S, Pellerin C, Badia A. Molecular Origin of the Odd-Even Effect of Macroscopic Properties of n-Alkanethiolate Self-Assembled Monolayers: Bulk or Interface? J Am Chem Soc 2020; 142:13051-13061. [PMID: 32597648 DOI: 10.1021/jacs.0c04288] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidating the influence of the monolayer interface versus bulk on the macroscopic properties (e.g., surface hydrophobicity, charge transport, and electron transfer) of organic self-assembled monolayers (SAMs) chemically anchored to metal surfaces is a challenge. This article reports the characterization of prototypical SAMs of n-alkanethiolates on gold (CH3(CH2)nSAu, n = 6-19) at the macroscopic scale by electrochemical impedance spectroscopy and contact angle goniometry, and at the molecular level, by infrared reflection absorption spectroscopy. The SAM capacitance, dielectric constant, and surface hydrophobicity exhibit dependencies on both the length (n) and parity (nodd or neven) of the polymethylene chain. The peak positions of the CH2 stretching modes indicate a progressive increase in the chain conformational order with increasing n between n = 6 and 16. SAMs of nodd have a greater degree of structural gauche defects than SAMs of neven. The peak intensities and positions of the CH3 stretching modes are chain length independent but show an odd-even alternation of the spatial orientation of the terminal CH3. The correlations between the different data trends establish that the chain length dependencies of the dielectric constant and surface hydrophobicity originate from changes in the polymethylene chain conformation (bulk), while the odd-even variation arises primarily from a difference in the chemical composition of the interface related to the terminal group orientation. These findings provide new physical insights into the structure-property relation of SAMs for the design of ultrathin film dielectrics as well as the understanding of stereostructural effects on the electrical characteristics of tunnel junctions.
Collapse
Affiliation(s)
- Fadwa Ben Amara
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Eric R Dionne
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Sahar Kassir
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Christian Pellerin
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Antonella Badia
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| |
Collapse
|
17
|
Pradeilles JA, Zhong S, Baglyas M, Tarczay G, Butts CP, Myers EL, Aggarwal VK. Odd-even alternations in helical propensity of a homologous series of hydrocarbons. Nat Chem 2020; 12:475-480. [PMID: 32123339 DOI: 10.1038/s41557-020-0429-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 01/24/2020] [Indexed: 11/09/2022]
Abstract
Odd and even homologues of some n-alkane-based systems are known to exhibit notably different trends in solid-state properties; a well-known illustration is the zigzag plot of their melting point versus chain length. Odd-even effects in the solid state often arise from intermolecular interactions that involve fully extended molecules. These effects have also been observed in less condensed phases, such as self-assembled monolayers; however, the origins of these effects in such systems can be difficult to determine. Here we combined NMR and computational analysis to show that all-syn contiguously methyl-substituted hydrocarbons, with chain lengths from C6 to C11, exhibit a dramatic odd-even effect in helical propensity. The even- and odd-numbered hydrocarbons populate regular and less-controlled helical conformations, respectively. This knowledge will guide the design of helical hydrocarbons as rigid scaffolds or as hydrophobic components in soft materials.
Collapse
Affiliation(s)
| | - Siying Zhong
- School of Chemistry, University of Bristol, Bristol, UK
| | - Márton Baglyas
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, Eötvös University, Budapest, Hungary.,MTA-ELTE, Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, Eötvös University, Budapest, Hungary
| | - György Tarczay
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, Eötvös University, Budapest, Hungary.,MTA-ELTE, Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, Eötvös University, Budapest, Hungary
| | - Craig P Butts
- School of Chemistry, University of Bristol, Bristol, UK.
| | - Eddie L Myers
- School of Chemistry, National University of Ireland Galway, Galway, Ireland.
| | | |
Collapse
|
18
|
Song H, Kim T, Kang S, Jin H, Lee K, Yoon HJ. Ga-Based Liquid Metal Micro/Nanoparticles: Recent Advances and Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1903391. [PMID: 31583849 DOI: 10.1002/smll.201903391] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/21/2019] [Indexed: 05/20/2023]
Abstract
Liquid metals are emerging as fluidic inorganic materials in various research fields. Micro- and nanoparticles of Ga and its alloys have received particular attention in the last decade due to their non toxicity and accessibility in ambient conditions as well as their interesting chemical, physical, mechanical, and electrical properties. Unique features such as a fluidic nature and self-passivating oxide skin make Ga-based liquid metal particles (LMPs) distinguishable from conventional inorganic particles in the context of synthesis and applications. Here, recent advances in the bottom-up and top-down synthetic methods of Ga-based LMPs, their physicochemical properties, and their applications are summarized. Finally, the current status of the LMPs is highlighted and perspectives on future directions are also provided.
Collapse
Affiliation(s)
- Hyunsun Song
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Taekyung Kim
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Seohyun Kang
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Haneul Jin
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Kwangyeol Lee
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Hyo Jae Yoon
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul, 02841, Republic of Korea
| |
Collapse
|
19
|
Xie Z, Bâldea I, Frisbie CD. Energy Level Alignment in Molecular Tunnel Junctions by Transport and Spectroscopy: Self-Consistency for the Case of Alkyl Thiols and Dithiols on Ag, Au, and Pt Electrodes. J Am Chem Soc 2019; 141:18182-18192. [PMID: 31617711 DOI: 10.1021/jacs.9b08905] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report here an extensive study of transport and electronic structure of molecular junctions based on alkyl thiols (CnT; n = 7, 8, 9, 10, 12) and dithiols (CnDT; n = 8, 9, 10) with various lengths contacted with different metal electrodes (Ag, Au, Pt). The dependence of the low-bias resistance (R) on contact work function indicates that transport is HOMO-assisted (p-type transport). Analysis of the current-voltage (I-V) characteristics for CnT and CnDT tunnel junctions with the analytical single-level model (SLM) provides both the HOMO-Fermi energy offset εhtrans and the average molecule-electrode coupling (Γ) as a function of molecular length (n), electrode work function (Φ), and the number of chemical contacts (one or two). The SLM analysis reveals a strong Fermi level (EF) pinning effect in all the junctions, i.e., εhtrans changes very little with n, Φ, and the number of chemical contacts, but Γ depends strongly on these variables. Significantly, independent measurements of the HOMO-Fermi level offset (εhUPS) by ultraviolet photoelectron spectroscopy (UPS) for CnT and CnDT SAMs agree remarkably well with the transport-estimated εhtrans. This result provides strong evidence for hole transport mediated by localized HOMO states at the Au-thiol interface, and not by the delocalized σ states in the C-C backbones, clarifying a long-standing issue in molecular electronics. Our results also substantiate the application of the single-level model for quantitative, unified understanding of transport in benchmark molecular junctions.
Collapse
Affiliation(s)
- Zuoti Xie
- Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Ioan Bâldea
- Theoretische Chemie , Universität Heidelberg , INF 229 , D-69120 Heidelberg , Germany
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| |
Collapse
|
20
|
Cheng HW, Wu ZP, Yan S, Li J, Shan S, Wang L, Porter MD, Zhong CJ. A simple vaporous probe with atomic-scale sensitivity to structural ordering and orientation of molecular assembly. Chem Sci 2019; 10:7104-7110. [PMID: 31588278 PMCID: PMC6677115 DOI: 10.1039/c9sc01656b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/12/2019] [Indexed: 11/29/2022] Open
Abstract
Understanding the structural ordering and orientation of interfacial molecular assemblies requires an insight into the penetration depth of the probe molecules which determines the interfacial reactivity. In contrast to the conventional liquid probe-based contact angle measurement in which penetration depth is complicated by the liquid cohesive interaction, we report here a new approach that features a simple combination of vaporous hexane, which involves only van der Waals interaction, and quartz crystal microbalance operated at the third harmonic resonance, which is sensitive to sub-monolayer (0.2%) adsorption. Using this combination, we demonstrated the ability of probing the structural ordering and orientation of the self-assembled monolayers with a sensitivity from penetrating the top portion of the monolayers to interacting with the very top atomic structure at the interface. The determination of the dependence of the adsorption energy of vaporous hexane on the penetration depth in the molecular assembly allowed us to further reveal the atomic-scale origin of the odd-even oscillation, which is also substantiated by density functional theory calculations. The findings have broader implications for designing interfacial reactivities of molecular assemblies with atomic-scale depth precision.
Collapse
Affiliation(s)
- Han-Wen Cheng
- School of Chemical and Environmental Engineering , Shanghai Institute of Technology , Shanghai 201418 , China .
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| | - Zhi-Peng Wu
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| | - Shan Yan
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| | - Jing Li
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| | - Shiyao Shan
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| | - Lichang Wang
- Department of Chemistry and Biochemistry , Southern Illinois University , Carbondale , Illinois 62901 , USA
| | - Marc D Porter
- Department of Chemistry and Chemical Engineering , University of Utah , Salt Lake City , Utah 84112 , USA .
| | - Chuan-Jian Zhong
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , USA .
| |
Collapse
|
21
|
Assunção IP, Carneiro Neto AN, Moura RT, Pedroso CCS, Silva IGN, Felinto MCFC, Teotonio EES, Malta OL, Brito HF. Odd-Even Effect on Luminescence Properties of Europium Aliphatic Dicarboxylate Complexes. Chemphyschem 2019; 20:1931-1940. [PMID: 31231943 DOI: 10.1002/cphc.201900603] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Indexed: 01/04/2023]
Abstract
The odd-even effect in luminescent [Eu2 (L)3 (H2 O)x ]⋅y(H2 O) complexes with aliphatic dicarboxylate ligands (L: OXA, MAL, SUC, GLU, ADP, PIM, SUB, AZL, SEB, UND, and DOD, where x=2-6 and y=0-4), prepared by the precipitation method, was observed for the first time in lanthanide compounds. The final dehydration temperatures of the Eu3+ complexes show a zigzag pattern as a function of the carbon chain length of the dicarboxylate ligands, leading to the so-called odd-even effect. The FTIR data confirm the ligand-metal coordination via the mixed mode of bridge-chelate coordination, except for the Eu3+ -oxalate complex. XRD results indicate that the highly crystalline materials belong to the monoclinic system. The odd-even effect on the 4 f-4 f luminescence intensity parameters (Ω2 and Ω4 ) is explained by using an extension of the dynamic coupling mechanism, herein named the ghost-atom model. In this method, the long-range polarizabilities ( α * ) were simulated by a ghost atom located at the middle of each ligand chain. The values of α * were estimated using the localized molecular orbital approach. The emission intrinsic quantum yield ( Q L n L n ) of the Eu3+ complexes also presented an the odd-even effect, successfully explained in terms of the zigzag behavior shown by the Ω2 and Ω4 intensity parameters. Luminescence quenching due to water molecules in the first coordination sphere is also discussed and rationalized.
Collapse
Affiliation(s)
- Israel P Assunção
- Department of Fundamental Chemistry Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, São Paulo-SP, 05508-000, Brazil
| | - Albano N Carneiro Neto
- Department of Fundamental Chemistry, Federal University of Pernambuco, Av. Prof. Moraes Rego, Recife-PE, 50670-901, Brazil.,Physics Department and CICECO-Aveiro Institute of Materials, University of Aveiro Campus Universitário de Santiago, Aveiro, 3810-193, Portugal
| | - Renaldo T Moura
- Department of Chemistry and Physics, Federal University of Paraíba, Campus II Cidade Universitária, Areia-PB, 58397-000, Brazil
| | - Cássio C S Pedroso
- Department of Fundamental Chemistry Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, São Paulo-SP, 05508-000, Brazil
| | - Ivan G N Silva
- Department of Fundamental Chemistry Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, São Paulo-SP, 05508-000, Brazil
| | - Maria C F C Felinto
- Nuclear and Energy Research Institute-IPEN/CNEN, Av. Prof. Lineu Prestes, São Paulo-SP, 05508-000, Brazil
| | - Ercules E S Teotonio
- Department of Chemistry, Federal University of Paraíba Jardim Universitário,-João Pessoa-PB, 58051-970, Brazil
| | - Oscar L Malta
- Department of Fundamental Chemistry, Federal University of Pernambuco, Av. Prof. Moraes Rego, Recife-PE, 50670-901, Brazil
| | - Hermi F Brito
- Department of Fundamental Chemistry Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, São Paulo-SP, 05508-000, Brazil
| |
Collapse
|
22
|
Du W, Han Y, Hu H, Chu HS, Annadata HV, Wang T, Tomczak N, Nijhuis CA. Directional Excitation of Surface Plasmon Polaritons via Molecular Through-Bond Tunneling across Double-Barrier Tunnel Junctions. NANO LETTERS 2019; 19:4634-4640. [PMID: 31184489 DOI: 10.1021/acs.nanolett.9b01665] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Directional excitation of surface plasmon polaritons (SPPs) by electrical means is important for the integration of plasmonics with molecular electronics or steering signals toward other components. We report electrically driven SPP sources based on quantum mechanical tunneling across molecular double-barrier junctions, where the tunneling pathway is defined by the molecules' chemical structure as well as by their tilt angle with respect to the surface normal. Self-assembled monolayers of S(CH2)nBPh (BPh = biphenyl, n = 1-7) on Au, where the alkyl chain and the BPh units define two distinct tunnel barriers in series, were used to demonstrate and control the geometrical effects. The tilt angle of the BPh unit with respect to the surface normal depends on the value of n, and is 45° when n is even and 23° when n is odd. The tilt angle of the alkyl chain is fixed at 30° and independent of n. For values of n = 1-3, SPPs are directionally launched via directional tunneling through the BPh units. For values of n > 3, tunneling along the alkyl chain dominates the SPP excitation. Molecular level control of directionally launching SPPs is achieved without requiring additional on-chip optical elements, such as antennas, or external elements, such as light sources. Using the molecular tunneling junctions, we provide the first direct experimental demonstration of molecular double-barrier tunneling junctions.
Collapse
Affiliation(s)
- Wei Du
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Yingmei Han
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Hongting Hu
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Hong-Son Chu
- Department of Electronics and Photonics, Institute of High Performance Computing , A*STAR (Agency for Science, Technology and Research) , 1 Fusionopolis Way, #16-16 Connexis , 138632 Singapore
| | - Harshini V Annadata
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Tao Wang
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
| | - Nikodem Tomczak
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
- Institute of Materials Research and Engineering , A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis , 138634 Singapore
| | - Christian A Nijhuis
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , 117543 Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
| |
Collapse
|
23
|
Duffin TJ, Nerngchamnong N, Thompson D, Nijhuis CA. Direct measurement of the local field within alkyl-ferrocenyl-alkanethiolate monolayers: Importance of the supramolecular and electronic structure on the voltammetric response and potential profile. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.04.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
24
|
Li H, Garner MH, Shangguan Z, Chen Y, Zheng Q, Su TA, Neupane M, Liu T, Steigerwald ML, Ng F, Nuckolls C, Xiao S, Solomon GC, Venkataraman L. Large Variations in the Single-Molecule Conductance of Cyclic and Bicyclic Silanes. J Am Chem Soc 2018; 140:15080-15088. [DOI: 10.1021/jacs.8b10296] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - Marc H. Garner
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Zhichun Shangguan
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University, Shanghai 200234, China
| | - Yan Chen
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University, Shanghai 200234, China
| | - Qianwen Zheng
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University, Shanghai 200234, China
| | | | | | - Taifeng Liu
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University, Shanghai 200234, China
| | | | | | | | - Shengxiong Xiao
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University, Shanghai 200234, China
| | - Gemma C. Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | | |
Collapse
|
25
|
Chen J, Kim M, Gathiaka S, Cho SJ, Kundu S, Yoon HJ, Thuo MM. Understanding Keesom Interactions in Monolayer-Based Large-Area Tunneling Junctions. J Phys Chem Lett 2018; 9:5078-5085. [PMID: 30126267 DOI: 10.1021/acs.jpclett.8b01731] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Charge transport across self-assembled monolayers (SAMs) has been widely studied. Discrepancies of charge tunneling data that arise from various studies, however, call for efforts to develop new statistical analytical approaches to understand charge tunneling across SAMs. Structure-property studies on charge tunneling across SAM-based junctions have largely been through comparison of average tunneling rates and associated variance. These early moments (especially the average) are dominated by barrier width-a static property of the junction. In this work, we show that analysis of higher statistical moments (skewness and kurtosis) reveals the dynamic nature of the tunnel junction. Intramolecular Keesom (dipole-dipole) interactions dynamically fluctuate with bias as dictated by stereoelectronic limitations. Analyzing variance in the distribution of tunneling data instead of the first statistical moment (average), for a series of n-alkanethiols containing internal amide and aromatic terminal groups, we observe that the direction of dipole moments affects molecule-electrode coupling. An applied bias induces changes in the tunneling probability, affecting the distribution of tunneling paths in large-area molecular junctions.
Collapse
Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering , Iowa State University , Ames , Iowa 50010 , United States
| | - Miso Kim
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Symon Gathiaka
- School of Pharmacy and Pharmaceutical Science , University of California , La Jolla , California 92093-0657 , United States
| | - Soo Jin Cho
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Souvik Kundu
- Department of Electrical and Computer Engineering , Iowa State University , Ames , Iowa 50010 , United States
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seongbuk-gu , Seoul 02841 , South Korea
| | - Martin M Thuo
- Department of Materials Science and Engineering , Iowa State University , Ames , Iowa 50010 , United States
| |
Collapse
|
26
|
Kakihara S, Saeki M, Ichimura S, Tamaki Y, Miyamura K. Inversion of Odd-Even Effect Observed in the Crystal Structure of ω-Cyclohexylalkylammonium-[Ni(dmit) 2] − Salts. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2018. [DOI: 10.1246/bcsj.20180090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Shunta Kakihara
- Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Masahiro Saeki
- Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Shuhei Ichimura
- Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Yoshinori Tamaki
- School of Dentistry, Faculty of Dentistry, Meikai University, 1-1 Keyakidai, Sakado, Saitama 350-0283, Japan
| | - Kazuo Miyamura
- Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| |
Collapse
|
27
|
Hoy EP, Mazziotti DA, Seideman T. Development and application of a 2-electron reduced density matrix approach to electron transport via molecular junctions. J Chem Phys 2018; 147:184110. [PMID: 29141419 DOI: 10.1063/1.4986804] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Can an electronic device be constructed using only a single molecule? Since this question was first asked by Aviram and Ratner in the 1970s [Chem. Phys. Lett. 29, 277 (1974)], the field of molecular electronics has exploded with significant experimental advancements in the understanding of the charge transport properties of single molecule devices. Efforts to explain the results of these experiments and identify promising new candidate molecules for molecular devices have led to the development of numerous new theoretical methods including the current standard theoretical approach for studying single molecule charge transport, i.e., the non-equilibrium Green's function formalism (NEGF). By pairing this formalism with density functional theory (DFT), a wide variety of transport problems in molecular junctions have been successfully treated. For some systems though, the conductance and current-voltage curves predicted by common DFT functionals can be several orders of magnitude above experimental results. In addition, since density functional theory relies on approximations to the exact exchange-correlation functional, the predicted transport properties can show significant variation depending on the functional chosen. As a first step to addressing this issue, the authors have replaced density functional theory in the NEGF formalism with a 2-electron reduced density matrix (2-RDM) method, creating a new approach known as the NEGF-RDM method. 2-RDM methods provide a more accurate description of electron correlation compared to density functional theory, and they have lower computational scaling compared to wavefunction based methods of similar accuracy. Additionally, 2-RDM methods are capable of capturing static electron correlation which is untreatable by existing NEGF-DFT methods. When studying dithiol alkane chains and dithiol benzene in model junctions, the authors found that the NEGF-RDM predicts conductances and currents that are 1-2 orders of magnitude below those of B3LYP and M06 DFT functionals. This suggests that the NEGF-RDM method could be a viable alternative to NEGF-DFT for molecular junction calculations.
Collapse
Affiliation(s)
- Erik P Hoy
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - David A Mazziotti
- Department of Chemistry and The James Frank Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Tamar Seideman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| |
Collapse
|
28
|
Chang B, Martin A, Gregory P, Kundu S, Du C, Orondo M, Thuo M. Functional Materials through Surfaces and Interfaces. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
29
|
Duong VV, Ayzner AL. Influence of conjugation length on ultrafast electronic tunneling in organic semiconductor thin films. Phys Chem Chem Phys 2018; 20:25085-25095. [DOI: 10.1039/c8cp04746d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron delocalization in conjugated organic molecules is a rate-limiting step in maximizing the photo conversion efficiency of next generation photovoltaics and molecular electronics.
Collapse
|
30
|
Chen J, Giroux TJ, Nguyen Y, Kadoma AA, Chang BS, VanVeller B, Thuo MM. Understanding interface (odd–even) effects in charge tunneling using a polished EGaIn electrode. Phys Chem Chem Phys 2018; 20:4864-4878. [DOI: 10.1039/c7cp07531f] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Charge transport across large area molecular tunneling junctions is widely studied due to its potential in the development of quantum electronic devices.
Collapse
Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| | - Thomas J. Giroux
- Department of Mechanical Engineering
- Iowa State University
- Ames
- USA
| | - Yen Nguyen
- Department of Chemistry
- Iowa State University
- Ames
- USA
| | - Atte A. Kadoma
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| | - Boyce S. Chang
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| | | | - Martin M. Thuo
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| |
Collapse
|
31
|
Chen J, Wang Z, Oyola-Reynoso S, Thuo MM. Properties of Self-Assembled Monolayers Revealed via Inverse Tensiometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13451-13467. [PMID: 28777587 DOI: 10.1021/acs.langmuir.7b01937] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembled monolayers (SAMs) have emerged as a simple platform technology and hence have been broadly studied. With advances in state-of-the-art fabrication and characterization methods, new insights into SAM structure and related properties have been delineated, albeit with some discrepancies and/or incoherencies. Some discrepancies, especially between experimental and theoretical work, are in part due to the misunderstanding of subtle structural features such as phase evolution and SAM quality. Recent work has, however, shown that simple techniques, such as the measurement of static contact angles, can be used to delineate otherwise complex properties of the SAM, especially when complemented by other more advanced techniques. In this article, we highlight the effect of nanoscale substrate asperities and molecular chain length on the SAM structure and associated properties. First, surfaces with tunable roughness are prepared on both Au and Ag, and their corresponding n-alkanethiolate SAMs are characterized through wetting and spectroscopy. From these data, chain-length- and substrate-morphology-dependent limits to the odd-even effect (structure and properties vary with the number of carbons in the molecules and the nature of the substrate), parametrization of gauche defect densities, and structural phase evolution (liquidlike, waxy, crystalline interfaces) are deduced. An evaluation of the correlation between the effect of roughness and the components of surface tension (polar-γp and dispersive-γd) reveals that wetting, at nanoscale rough surfaces, evolves proportionally with the ratio of the two components of surface tension. The evolution of conformational order is captured over a range of molecular lengths and parametrized through a dimensionless number, χc. By deploying a well-known tensiometry technique (herein the liquid is used to characterize the solid, hence the term inverse tensiometry) to characterize SAMs, we demonstrate that complex molecular-level phenomena in SAMs can be understood through simplicity.
Collapse
Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Martin M Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| |
Collapse
|
32
|
Zhang Y, Qiu X, Gordiichuk P, Soni S, Krijger TL, Herrmann A, Chiechi RC. Mechanically and Electrically Robust Self-Assembled Monolayers for Large-Area Tunneling Junctions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:14920-14928. [PMID: 28729893 PMCID: PMC5512119 DOI: 10.1021/acs.jpcc.7b03853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/12/2017] [Indexed: 05/28/2023]
Abstract
This paper examines the relationship between mechanical deformation and the electronic properties of self-assembled monolayers (SAMs) of the oligothiophene 4-([2,2':5',2″:5″,2‴-quaterthiophen]-5-yl)butane-1-thiol (T4C4) in tunneling junctions using conductive probe atomic force microscopy (CP-AFM) and eutectic Ga-In (EGaIn). We compared shifts in conductivity, transition voltages of T4C4 with increasing AFM tip loading force to alkanethiolates. While these shifts result from an increasing tilt angle from penetration of the SAM by the AFM tip for the latter, we ascribe them to distortions of the π system present in T4C4, which is more mechanically robust than alkanethiolates of comparable length; SAMs comprising T4C4 shows about five times higher Young's modulus than alkanethiolates. Density functional theory calculations confirm that mechanical deformations shift the barrier height due to changes in the frontier orbitals caused by small rearrangements to the conformation of the quaterthiophene moiety. The mechanical robustness of T4C4 manifests as an increased tolerance to high bias in large-area EGaIn junctions suggesting that electrostatic pressure plays a significant role in the shorting of molecular junctions at high bias.
Collapse
Affiliation(s)
- Yanxi Zhang
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Xinkai Qiu
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Pavlo Gordiichuk
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Saurabh Soni
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Theodorus L. Krijger
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Andreas Herrmann
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ryan C. Chiechi
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Zernike
Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| |
Collapse
|
33
|
Chen J, Chang B, Oyola-Reynoso S, Wang Z, Thuo M. Quantifying Gauche Defects and Phase Evolution in Self-Assembled Monolayers through Sessile Drops. ACS OMEGA 2017; 2:2072-2084. [PMID: 31457561 PMCID: PMC6640986 DOI: 10.1021/acsomega.7b00355] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/04/2017] [Indexed: 05/31/2023]
Abstract
Self-assembled monolayers (SAMs) are widely used in surface modifications, specifically in tuning the surface chemistry of materials. The structure and properties of SAMs have been extensively studied often with sophisticated tools, even for the simplest n-alkanethiolate SAMs. In SAMs, especially in linear n-alkanethiolates, the properties are dependent on the chain length, which is best manifested in the so-called odd-even effect, a simple yet not fully understood phenomenon. One main challenge is fully delineating the origin of length-dependent properties, which can be due to the structure (ideal SAMs), defect evolution, or substrate-molecule effects. This study demonstrates that utilizing the wetting behavior of polar (water) and nonpolar (hexadecane (HD)) solvents on n-alkanethiolate SAMs formed on ultraflat gold and silver surfaces, the evolution of chain-length-dependent gauche defects can be revealed and parameterized through a newly defined dimensionless number (χ). The observation of the odd-even effect in hydrophobicity, however, depends on the thiol chain length, and it was only observed on longer-chain (>C8) molecules. The trend in this odd-even effect demonstrates that there are three main transitions in the nature of wetting, hence structure, across n-alkanethiols. From wetting with HD, the role of dispersive components in wetting reveal that the SAMs are dynamic, which we attribute to rotations associated with previously reported evolution in gauche defects and changes in packing density. Therefore, from re-expression of the Young-Dupre equation, we define a new dimensionless number associated with molecular conformations, whose periodicity mirrors the energetics of Goodman's conformations of n-alkanes in unbound states and associated four- or two-twist turns. Therefore, we infer that the evolution in surface energy is largely due to molecular conformations and associated relaxations of the bound thiolates.
Collapse
Affiliation(s)
- Jiahao Chen
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Division
of Materials Science and Engineering, Ames
Laboratory, Ames, Iowa 50011, United
States
- Micro-Electronic
Research Center, Iowa State University, 133 Applied Sciences Complex I,
1925 Scholl Road, Ames, Iowa 50011, United States
| | - Boyce Chang
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Division
of Materials Science and Engineering, Ames
Laboratory, Ames, Iowa 50011, United
States
| | - Stephanie Oyola-Reynoso
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
| | - Zhengjia Wang
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
| | - Martin Thuo
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Micro-Electronic
Research Center, Iowa State University, 133 Applied Sciences Complex I,
1925 Scholl Road, Ames, Iowa 50011, United States
- Biopolymer
and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University, 1041 Food Sciences Building, Ames, Iowa 50011, United States
| |
Collapse
|
34
|
Gryn'ova G, Ollitrault PJ, Corminboeuf C. Guidelines and diagnostics for charge carrier tuning in thiophene-based wires. Phys Chem Chem Phys 2017; 19:23254-23259. [DOI: 10.1039/c7cp04295g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Reported experimental trends in charge carrier tuning in single molecule junctions of oligothiophene-based wires are rationalized by means of frontier molecular orbital theory.
Collapse
Affiliation(s)
- Ganna Gryn'ova
- Institut des Sciences et Ingénierie Chimiques, École polytechnique fédérale de Lausanne
- CH-1015 Lausanne
- Switzerland
| | - Pauline J. Ollitrault
- Institut des Sciences et Ingénierie Chimiques, École polytechnique fédérale de Lausanne
- CH-1015 Lausanne
- Switzerland
| | - Clémence Corminboeuf
- Institut des Sciences et Ingénierie Chimiques, École polytechnique fédérale de Lausanne
- CH-1015 Lausanne
- Switzerland
| |
Collapse
|
35
|
Chen J, Liu J, Tevis ID, Andino RS, Miller CM, Ziegler LD, Chen X, Thuo MM. Spectroscopic evidence for the origin of odd–even effects in self-assembled monolayers and effects of substrate roughness. Phys Chem Chem Phys 2017; 19:6989-6995. [DOI: 10.1039/c6cp07580k] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper reports the effects of substrate roughness on the odd–even effect in n-alkanethiolate self-assembled monolayers (SAMs) probed by vibrational sum frequency generation (SFG) spectroscopy.
Collapse
Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
- Microelectronic Research Centre
| | - Jian Liu
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | - Ian D. Tevis
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| | - Richard S. Andino
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | | | | | - Xin Chen
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | - Martin M. Thuo
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
- Microelectronic Research Centre
| |
Collapse
|
36
|
Thompson D, Nijhuis CA. Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers. Acc Chem Res 2016; 49:2061-2069. [PMID: 27598413 DOI: 10.1021/acs.accounts.6b00256] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This Account describes a body of research in atomic level design, synthesis, physicochemical characterization, and macroscopic electrical testing of molecular devices made from ferrocene-functionalized alkanethiol molecules, which are molecular diodes, with the aim to identify, and resolve, the failure modes that cause leakage currents. The mismatch in size between the ferrocene headgroup and alkane rod makes waxlike highly dynamic self-assembled monolayers (SAMs) on coinage metals that show remarkable atomic-scale sensitivity in their electrical properties. Our results make clear that molecular tunnel junction devices provide an excellent testbed to probe the electronic and supramolecular structures of SAMs on inorganic substrates. Contacting these SAMs to a eutectic "EGaIn" alloy top-electrode, we designed highly stable long-lived molecular switches of the form electrode-SAM-electrode with robust rectification ratios of up to 3 orders of magnitude. The graphic that accompanies this conspectus displays a computed SAM packing structure, illustrating the lollipop shape of the molecules that gives dynamic SAM supramolecular structures and also the molecule-electrode van der Waals (vdW) contacts that must be controlled to form good SAM-based devices. In this Account, we first trace the evolution of SAM-based electronic devices and rationalize their operation using energy level diagrams. We describe the measurement of device properties using near edge X-ray absorption fine structure spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy complemented by molecular dynamics and electronic structure calculations together with large numbers of electrical measurements. We discuss how data obtained from these combined experimental/simulation codesign studies demonstrate control over the supramolecular and electronic structure of the devices, tuning odd-even effects to optimize inherent packing tendencies of the molecules in order to minimize leakage currents in the junctions. It is now possible, but still very costly to create atomically smooth electrodes and we discuss progress toward masking electrode imperfections using cooperative molecule-electrode contacts that are only accessible by dynamic SAM structures. Finally, the unique ability of SAM devices to achieve simultaneously high and atom-sensitive electrical switching is summarized and discussed. While putting these structures to work as real world electronic devices remains very challenging, we speculate on the scientific and technological advances that are required to further improve electronic and supramolecular structure, toward the creation of high yields of long-lived molecular devices with (very) large, reproducible rectification ratios.
Collapse
Affiliation(s)
- Damien Thompson
- Department
of Physics, Bernal Institute, University of Limerick, Limerick V94 T9PX, Ireland
| | - Christian A. Nijhuis
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
| |
Collapse
|
37
|
Wang Z, Chen J, Gathiaka SM, Oyola-Reynoso S, Thuo M. Effect of Substrate Morphology on the Odd-Even Effect in Hydrophobicity of Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10358-10367. [PMID: 27642814 DOI: 10.1021/acs.langmuir.6b01681] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Surface roughness, often captured through root-mean-square roughness (Rrms), has been shown to impact the quality of self-assembled monolayers (SAMs) formed on coinage metals. Understanding the effect of roughness on hydrophobicity of SAMs, however, is complicated by the odd-even effect-a zigzag oscillation in contact angles with changes in molecular length. We recently showed that for surfaces with Rrms > 1 nm, the odd-even effect in hydrophobicity cannot be empirically observed. In this report, we compare wetting properties of SAMs on Ag and Au surfaces of different morphologies across the Rrms ∼ 1 nm limit. We prepared surfaces with comparable properties (grain sizes and Rrms) and assessed the wetting properties of resultant SAMs. Substrates with Rrms either below or above the odd-even limit were investigated. With smoother surfaces (lower Rrms), an inverted asymmetric odd-even zigzag oscillation in static contact angles (θs) was observed with change from Au to Ag. Asymmetry in odd-even oscillation in Au was attributed to a larger change in θs from odd to even number of carbons in the n-alkanethiol and vice versa for Ag. For rougher surfaces, no odd-even effect was observed; however, a gradual increase in the static contact angle was observed. Increase in the average grain sizes (>3 times larger) on rough surfaces did not lead to significant difference in the wetting properties, suggesting that surface roughness significantly dominated the nature of the SAMs. We therefore infer that the predicted roughness-dependent limit to the observation of the odd-even effect in wetting properties of n-alkanethiols cannot be overcome by creating surfaces with large grain sizes for surfaces with Rrms > 1 nm. We also observed that the differences between Au and Ag surfaces are dominated by differences in the even-numbered SAMs, but this difference vanishes with shorter molecular chain length (≤C3).
Collapse
Affiliation(s)
- Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-Electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
| | - Symon M Gathiaka
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego , Pharmaceutical Sciences Building, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-Electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
- Biopolymer and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University , 1041 Food Sciences Building, Ames, Iowa 50011 United States
| |
Collapse
|
38
|
Carlotti M, Degen M, Zhang Y, Chiechi RC. Pronounced Environmental Effects on Injection Currents in EGaIn Tunneling Junctions Comprising Self-Assembled Monolayers. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:20437-20445. [PMID: 27738488 PMCID: PMC5053169 DOI: 10.1021/acs.jpcc.6b07089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/23/2016] [Indexed: 05/09/2023]
Abstract
Large-area tunneling junctions using eutectic Ga-In (EGaIn) as a top contact have proven to be a robust, reproducible, and technologically relevant platform for molecular electronics. Thus far, the majority of studies have focused on saturated molecules with backbones consisting mainly of alkanes in which the frontier orbitals are either highly localized or energetically inaccessible. We show that self-assembled monolayers of wire-like oligophenyleneethynylenes (OPEs), which are fully conjugated, only exhibit length-dependent tunneling behavior in a low-O2 environment. We attribute this unexpected behavior to the sensitivity of injection current on environment. We conclude that, contrary to previous reports, the self-limiting layer of Ga2O3 strongly influences transport properties and that the effect is related to the wetting behavior of the electrode. This result sheds light on the nature of the electrode-molecule interface and suggests that adhesive forces play a significant role in tunneling charge-transport in large-area molecular junctions.
Collapse
Affiliation(s)
- Marco Carlotti
- Stratingh Institute for Chemistry
& Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Maarten Degen
- Stratingh Institute for Chemistry
& Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Yanxi Zhang
- Stratingh Institute for Chemistry
& Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ryan C. Chiechi
- Stratingh Institute for Chemistry
& Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| |
Collapse
|
39
|
Wang Z, Chen J, Oyola-Reynoso S, Thuo M. Empirical Evidence for Roughness-Dependent Limit in Observation of Odd-Even Effect in Wetting Properties of Polar Liquids on n-Alkanethiolate Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8230-7. [PMID: 27448027 DOI: 10.1021/acs.langmuir.6b02159] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Substrate roughness influences the wetting properties of self-assembled monolayers (SAMs), but details on this dependency at the sub-nanometer level are still lacking. This study investigates the effect of surface roughness on interfacial properties of n-alkanethiolate SAMs, specifically wetting, and confirms the predicted limit to the observation of the odd-even effect in hydrophobicity. This article studies static contact angles of polar and nonpolar probe liquids on a series of n-alkanethiolate SAMs on surfaces with tunable roughness. We prepared Ag surfaces with root-mean-square roughness (Rrms) of ∼0.6-2.2 nm and compared the wetting properties of n-alkanethiolate SAMs fabricated on these surfaces. We measured the static contact angles, θs, formed between SAM and probe liquids [water, glycerol, and hexadecane]. Hexadecane showed an odd-even effect on all surfaces irrespective of the degree of roughness. Polar liquids (water and glycerol), however, showed a dependency on the roughness of the substrate with an odd-even effect observable only on smooth, but not rougher (Rrms ≥ 1.15 nm), surfaces. These results confirm that the previously predicted limit to observation of the odd-even effect in hydrophobicity (here extended to polar liquids) is real. From the results with glycerol, we infer that this limit is not limited just to hydrophobicity but may extend to other polar liquids. Results from hexadecane, however, suggest that this limit may not be a universal property of the SAM.
Collapse
Affiliation(s)
- Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
- Biopolymer and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University , 1041 Food Sciences Building, Ames, Iowa 50011 United States
| |
Collapse
|
40
|
Kovalchuk A, Egger DA, Abu-Husein T, Zojer E, Terfort A, Chiechi RC. Dipole-induced asymmetric conduction in tunneling junctions comprising self-assembled monolayers. RSC Adv 2016. [DOI: 10.1039/c6ra10471a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The collective action of embedded dipoles causes asymmetric tunneling charge-transport through self-assembled monolayers.
Collapse
Affiliation(s)
- Andrii Kovalchuk
- Stratingh Institute for Chemistry
- Zernike Institute for Advanced Materials
- University of Groningen
- 9747 AG Groningen
- The Netherlands
| | - David A. Egger
- Department of Materials and Interfaces
- Weizmann Institute of Science
- Rehovoth 76100
- Israel
| | - Tarek Abu-Husein
- Institut für Anorganishe und Analytische Chemie
- Universität Frankfurt
- 60438 Frankfurt
- Germany
| | - Egbert Zojer
- Institute of Solid State Physics
- NAWI Graz
- Graz University of Technology
- 8010 Graz
- Austria
| | - Andreas Terfort
- Institut für Anorganishe und Analytische Chemie
- Universität Frankfurt
- 60438 Frankfurt
- Germany
| | - Ryan C. Chiechi
- Stratingh Institute for Chemistry
- Zernike Institute for Advanced Materials
- University of Groningen
- 9747 AG Groningen
- The Netherlands
| |
Collapse
|
41
|
The Porter-Whitesides Discrepancy: Revisiting Odd-Even Effects in Wetting Properties of n-Alkanethiolate SAMs. COATINGS 2015. [DOI: 10.3390/coatings5041034] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
42
|
Sporrer J, Chen J, Wang Z, Thuo MM. Revealing the Nature of Molecule-Electrode Contact in Tunneling Junctions Using Raw Data Heat Maps. J Phys Chem Lett 2015; 6:4952-8. [PMID: 26618717 DOI: 10.1021/acs.jpclett.5b02300] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Mechanistic understanding of charge transport through molecular tunnel junctions requires reproducible and statistically relevant data sets. This challenge has been overcome by development of large area junctions, especially those based on liquid-metal physi-sorbed top-electrodes, such as eutectic gallium-indium. A challenge with these junctions, however, is an inability to diagnose the quality of contact between the top-electrode and the SAMs. Since tunneling currents are dependent on the distance between the two electrodes, we demonstrate that by analyzing all raw unfitted data derived from a measurement using heat-maps, one can deduce the quality of contact and other minor bias-dependent fluctuations in the charge transport behavior. We demonstrate that the use of 3D plots would be challenging to interpret, but adoption of heat maps clearly captures details on junction quality irrespective of the total size of the data set or molecules used. We propose representation of raw data, rather than reliance on statistics, as proof of quality junctions.
Collapse
Affiliation(s)
- Jacob Sporrer
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
| | - Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Martin M Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
- Biopolymer and Bio-composites Research Team, Center for Bioplastics and Bio-composites, Iowa State University , 1041 Food Sciences Building, Ames, Iowa 50011 United States
| |
Collapse
|