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Dehiwala Liyanage C, Ortiz-Garcia JJ, Struckmeier A, McCoy CL, Kienzler MA, Quardokus RC. A Scanning Tunneling Microscopy Study of the Photoisomerization of Diazocine. J Phys Chem Lett 2024; 15:4082-4087. [PMID: 38587451 DOI: 10.1021/acs.jpclett.4c00096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Azobenzenes are fascinating molecular machines that can reversibly transform between two isomeric forms by an external stimulus. Diazocine, a type of bridged azobenzene, has been shown to possess enhanced photoexcitation properties. Due to the distortion caused by the ethyl bridge in the E-isomer, the Z-form becomes the thermodynamically stable configuration. Despite a comprehensive understanding of its photophysical properties, there is still much to learn about the behavior of diazocine on a metal surface. Here we show the operando photoswitching of diazocine molecules deposited directly on a Au(111) surface using scanning tunneling microscopy. Molecules were shown to aggregate into disordered islands with edge sites being susceptible to photon-induced movement. A few molecules were shown to undergo directional movement under UV irradiation with the motion reversed under blue light exposure. These findings contribute new insight into the activity of single and ensemble molecular systems toward purposefully guided motion.
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Affiliation(s)
| | - José J Ortiz-Garcia
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Annalena Struckmeier
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Christian L McCoy
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Michael A Kienzler
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Rebecca C Quardokus
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
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2
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Liyanage CD, Ortiz-Garcia JJ, Struckmeier A, Kienzler M, Quardokus RC. Light-induced Photoswitching of 4-(Phenylazo)benzoic Acid on Au(111). Chemphyschem 2023; 24:e202300160. [PMID: 37369072 DOI: 10.1002/cphc.202300160] [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: 03/02/2023] [Revised: 06/13/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023]
Abstract
Photochromic molecules can undergo a reversible conversion between two isomeric forms upon exposure to external stimuli such as electromagnetic radiation. A significant physical transformation accompanying the photoisomerization process defines them as photoswitches, with potential applications in various molecular electronic devices. As such, a detailed understanding of the photoisomerization process on surfaces and the influence of the local chemical environment on switching efficiency is essential. Herein, we use scanning tunneling microscopy to observe the photoisomerization of 4-(phenylazo)benzoic acid (PABA) assembled on Au(111) in kinetically constrained metastable states guided by pulse deposition. Photoswitching is observed at low molecular density and is absent in tight-packed islands. Furthermore, switching events were noted in PABA molecules coadsorbed in a host octanethiol monolayer, suggesting an influence of the surrounding chemical environment on photoswitching efficiency.
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Affiliation(s)
| | - José J Ortiz-Garcia
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT, USA
| | - Annalena Struckmeier
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT, USA
| | - Michael Kienzler
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT, USA
| | - Rebecca C Quardokus
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT, USA
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3
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Du X, Zhang S, Wang L, Wang Y, Fan P, Jia W, Zhang P, Huang S. Single-Molecule Interconversion between Chiral Configurations of Boronate Esters Observed in a Nanoreactor. ACS NANO 2023; 17:2881-2892. [PMID: 36655995 DOI: 10.1021/acsnano.2c11286] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Isomers of some chemical compounds may be dynamically interconvertible. Due to a lack of sensing methods with a sufficient resolution, however, direct monitoring of such processes can be difficult. Engineered Mycobacterium smegmatis porin A (MspA) nanopores can be applied as nanoreactors so that chemical reactions can be directly monitored. Here, an MspA modified with a phenylboronic acid (PBA) adapter was prepared and was used to observe dynamic interconversion between chiral configurations of boronate esters, which appears as telegraphic switching on top of nanopore events. The mechanism of this behavior was further confirmed by trials with different halogenated catechols, dopamine, adenosine, 1,2-propanediol, and (2R,3R)-2,3-butanediol, and its generality has been demonstrated. These results suggest that an engineered MspA possesses an exceptional resolution in its monitoring of chemical reaction processes and may inspire the future design of nanopore small-molecule sensors.
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Affiliation(s)
- Xiaoyu Du
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Shanyu Zhang
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Liying Wang
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Yuqin Wang
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Pingping Fan
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Wendong Jia
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
| | - Panke Zhang
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
| | - Shuo Huang
- State Key Laboratory of Analytical Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023Nanjing, China
- Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, 210023Nanjing, China
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4
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Effects and Influence of External Electric Fields on the Equilibrium Properties of Tautomeric Molecules. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020695. [PMID: 36677753 PMCID: PMC9865840 DOI: 10.3390/molecules28020695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023]
Abstract
In this review, we have attempted to briefly summarize the influence of an external electric field on an assembly of tautomeric molecules and to what experimentally observable effects this interaction can lead to. We have focused more extensively on the influence of an oriented external electric field (OEEF) on excited-state intramolecular proton transfer (ESIPT) from the studies available to date. The possibilities provided by OEEF for regulating several processes and studying physicochemical processes in tautomers have turned this direction into an attractive area of research due to its numerous applications.
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5
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Zhao Y, Gobbi M, Hueso LE, Samorì P. Molecular Approach to Engineer Two-Dimensional Devices for CMOS and beyond-CMOS Applications. Chem Rev 2021; 122:50-131. [PMID: 34816723 DOI: 10.1021/acs.chemrev.1c00497] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two-dimensional materials (2DMs) have attracted tremendous research interest over the last two decades. Their unique optical, electronic, thermal, and mechanical properties make 2DMs key building blocks for the fabrication of novel complementary metal-oxide-semiconductor (CMOS) and beyond-CMOS devices. Major advances in device functionality and performance have been made by the covalent or noncovalent functionalization of 2DMs with molecules: while the molecular coating of metal electrodes and dielectrics allows for more efficient charge injection and transport through the 2DMs, the combination of dynamic molecular systems, capable to respond to external stimuli, with 2DMs makes it possible to generate hybrid systems possessing new properties by realizing stimuli-responsive functional devices and thereby enabling functional diversification in More-than-Moore technologies. In this review, we first introduce emerging 2DMs, various classes of (macro)molecules, and molecular switches and discuss their relevant properties. We then turn to 2DM/molecule hybrid systems and the various physical and chemical strategies used to synthesize them. Next, we discuss the use of molecules and assemblies thereof to boost the performance of 2D transistors for CMOS applications and to impart diverse functionalities in beyond-CMOS devices. Finally, we present the challenges, opportunities, and long-term perspectives in this technologically promising field.
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Affiliation(s)
- Yuda Zhao
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France.,School of Micro-Nano Electronics, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, 310027 Hangzhou, People's Republic of China
| | - Marco Gobbi
- Centro de Fisica de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, E-20018 Donostia-San Sebastián, Spain.,CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Luis E Hueso
- CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Paolo Samorì
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France
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6
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Diez Cabanes V, Van Dyck C, Osella S, Cornil D, Cornil J. Challenges for Incorporating Optical Switchability in Organic-Based Electronic Devices. ACS APPLIED MATERIALS & INTERFACES 2021; 13:27737-27748. [PMID: 34105343 DOI: 10.1021/acsami.1c05489] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Transistors operate by controlling the current flowing from a source to a drain electrode via a third electrode (gate), thus giving access to a binary treatment (ON/OFF or 0/1) of the signal currently exploited in microelectronics. Introducing a second independent lever to modulate the current would allow for more complex logic functions amenable to a single electronic component and hence to new opportunities for advanced electrical signal processing. One avenue is to add this second dimension with light by incorporating photochromic molecules in current organic-based electronic devices. In this Spotlight, we describe different concepts that have been implemented in organic thin films and in molecular junctions as well as some pitfalls that have been highlighted thanks to theoretical modeling.
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Affiliation(s)
- Valentin Diez Cabanes
- Laboratoire de Physique et Chimie Théoriques, Université de Lorraine & CNRS, 54000 Nancy, France
| | - Colin Van Dyck
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
| | - Silvio Osella
- Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warszawa, Poland
| | - David Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons, Belgium
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7
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Gulaczyk I, Kręglewski M. Floppy molecules—their internal dynamics, spectroscopy and applications. PHYSICAL SCIENCES REVIEWS 2021. [DOI: 10.1515/psr-2020-0035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Floppy molecules can be defined as molecules performing large amplitude vibrations (LAVs). There are different types of LAVs among which the most common are inversion and internal rotation. Molecules with LAVs have been of great interest for a very long time since their dynamic, geometry and molecular spectra were very often considered as a challenge. In the review, we present an outline of the history and development of various theoretical approaches concerning molecules with LAVs. Different types of LAVs are described with the emphasis on inversion tunneling (wagging) and internal rotation (torsion). Furthermore, strategies for building explicit and effective Hamiltonians are given and explained in detail using a hydrazine molecule, which is an exemplary molecule performing three LAVs—two inversions and one internal rotation. Since floppy molecules play a significant role in numerous areas as chemistry, pharmacy, astrophysics, biology, agriculture etc., we also provide an overview of their applications.
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Affiliation(s)
- Iwona Gulaczyk
- Faculty of Chemistry , Adam Mickiewicz University in Poznań , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland
| | - Marek Kręglewski
- Faculty of Chemistry , Adam Mickiewicz University in Poznań , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland
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8
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Riaz S, Friedrichs G. Vibrational sum-frequency generation study of molecular structure, sterical constraints and nonlinear optical switching contrast of mixed alkyl-azobenzene self-assembled monolayers. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2020-1655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Abstract
Self-assembled monolayers (SAMs) of azobenzene (AB) functionalized alkyl thiols on gold diluted with simple alkyl thiols provide a straightforward way to photochromic surfaces with high and tunable photoswitching efficiency. Trans-cis isomerization of the AB molecule changes the physical properties of the surface, including the nonlinear optical (NLO) response. Vibrational sum-frequency generation (VSFG) spectroscopy as a nonlinear type of laser spectroscopy offers surface- and orientation-sensitive insight into the molecular structure of mixed SAMs. In this study, VSFG as well as ultraviolet-visible (UV/Vis) spectroscopy has been employed to investigate the morphology, molecular structure, and NLO response of mixed SAMs with systematically varied surface composition. Methylazobenzene (MeAB) has been used as the molecular switch with the methyl substituent serving as orientational VSFG marker. Both short-chain and long-chain alkyl thiol co-ligands have been used to gain insight into the interplay between SAM structure and sterical constraints that are known to limit the free switching volume. Underlining the dominating role of sterical effects for controlling photochromic properties, a strong inhibition of the photoswitching efficiency and NLO response has been observed for the SAMs with an alkyl thiol co-ligand long enough to spatially extend into the layer of the MeAB chromophore. Overall, with <12% signal change, the relative NLO switching contrasts remained low in all cases. VSFG spectral trends clearly revealed that the presumably higher photoswitching efficiency upon dilution with the co-ligand is counteracted by a loss of structural order of the chromophore.
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Affiliation(s)
- Saira Riaz
- Islamabad College for Girls , F-6/2 , Islamabad, 44000 , Pakistan
| | - Gernot Friedrichs
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1, 24118 , Kiel , Germany
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9
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Imen H, Xiaonan S, Denis F, Frédéric L, Jean-Christophe L. Multi-functional switches of ditopic ligands with azobenzene central bridges at a molecular scale. NANOSCALE 2019; 11:23042-23048. [PMID: 31774086 DOI: 10.1039/c9nr06350a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ligands are designed to have ditopic bipyridine terminal groups linked through photochromic azobenzene central units, which exhibit multi-switchable properties by different external stimuli. The molecule can switch between cis-and trans-conformations at their bipyridine terminal groups upon protonation and at their central azobenzene units upon irradiation of photons. As a result, the system shows four different isomeric states: cis-TRANS, trans-TRANS, cis-CIS and trans-CIS. The four conformers are switched and are visualized by scanning tunneling microscopy at the solid-liquid interface, which gives a direct demonstration of the multi-functional switches at a molecular level.
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Affiliation(s)
- Hnid Imen
- Université de Paris, ITODYS, CNRS, UMR 7086, 15 rue J-A de Baïf, F-75013 Paris, France.
| | - Sun Xiaonan
- Université de Paris, ITODYS, CNRS, UMR 7086, 15 rue J-A de Baïf, F-75013 Paris, France.
| | - Frath Denis
- Université de Paris, ITODYS, CNRS, UMR 7086, 15 rue J-A de Baïf, F-75013 Paris, France. and Université Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - Lafolet Frédéric
- Université de Paris, ITODYS, CNRS, UMR 7086, 15 rue J-A de Baïf, F-75013 Paris, France.
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10
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Wang T, Du W, Tomczak N, Wang L, Nijhuis CA. In Operando Characterization and Control over Intermittent Light Emission from Molecular Tunnel Junctions via Molecular Backbone Rigidity. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1900390. [PMID: 31637155 PMCID: PMC6794720 DOI: 10.1002/advs.201900390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/19/2019] [Indexed: 05/06/2023]
Abstract
In principle, excitation of surface plasmons by molecular tunnel junctions can be controlled at the molecular level. Stable electrical excitation sources of surface plasmons are therefore desirable. Herein, molecular junctions are reported where tunneling charge carriers excite surface plasmons in the gold bottom electrodes via inelastic tunneling and it is shown that the intermittent light emission (blinking) originates from conformational dynamics of the molecules. The blinking rates, in turn, are controlled by changing the rigidity of the molecular backbone. Power spectral density analysis shows that molecular junctions with flexible aliphatic molecules blink, while junctions with rigid aromatic molecules do not.
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Affiliation(s)
- Tao Wang
- Department of ChemistryNational University of Singapore3 Science Drive 3117543SingaporeSingapore
| | - Wei Du
- Department of ChemistryNational University of Singapore3 Science Drive 3117543SingaporeSingapore
| | - Nikodem Tomczak
- Department of ChemistryNational University of Singapore3 Science Drive 3117543SingaporeSingapore
- Institute of Materials Research and EngineeringA*STAR (Agency for Science, Technology and Research)2 Fusionopolis Way, Innovis138634SingaporeSingapore
| | - Lejia Wang
- Department of ChemistryNational University of Singapore3 Science Drive 3117543SingaporeSingapore
| | - Christian A. Nijhuis
- Department of ChemistryNational University of Singapore3 Science Drive 3117543SingaporeSingapore
- Centre for Advanced 2D Materials and Graphene Research CentreNational University of Singapore6 Science Drive 2117546SingaporeSingapore
- NUSNNI NanocoreNational University of Singapore117411SingaporeSingapore
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11
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Geng WC, Sun H, Guo DS. Macrocycles containing azo groups: recognition, assembly and application. J INCL PHENOM MACRO 2018. [DOI: 10.1007/s10847-018-0819-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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12
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Frath D, Yokoyama S, Hirose T, Matsuda K. Photoresponsive supramolecular self-assemblies at the liquid/solid interface. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2018. [DOI: 10.1016/j.jphotochemrev.2017.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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13
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Affiliation(s)
- Evgeny Katz
- Department of Chemistry and Biomolecular Science; Clarkson University; Potsdam, NY 13699-5810 USA
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14
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Bâldea I. Floppy molecules as candidates for achieving optoelectronic molecular devices without skeletal rearrangement or bond breaking. Phys Chem Chem Phys 2018; 19:30842-30851. [PMID: 29135004 DOI: 10.1039/c7cp06428d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Molecular species investigated as possible candidates for molecular photoswitches often toggle between two (low and high conductance) conformations implying skeletal rearrangement, bond breaking, and substantial changes of molecular length. All these represent shortcomings that impede the switching speed and straightforward incorporation in nanodevices. In the present paper we propose a mechanism wherein the photoinduced switching is from a nonplanar conformation to a planar conformation, and involves neither skeletal rearrangement nor bond breaking or significant molecular length changes. Specifically, by choosing typical floppy molecules consisting of two benzene or benzene-like rings that can easily rotate relative to each other, we present results of both ab initio and DFT quantum chemical calculations demonstrating that the lowest electronic excitation corresponds to a planar molecular conformation (φ = 0), in contrast to the nonplanar ground state characterized by φ ≠ 0. Because the low bias conductance scales as G ∝ cos2 φ, the planar conformation has a higher conductance than the non-planar conformation, acting therefore as ON and OFF states of the molecular switch, respectively. We analyze recent experimental data on illuminated single-molecule junctions (E.-D. Fung et al., Nano Lett., 2017, 17, 1255) and show that the measured photoinduced conductance enhancement is consistent with the presently proposed mechanism. Furthermore, based on recent results demonstrating the substantial impact of the SAM coverage on the twisting angle (I. Bâldea, Faraday Discuss., 2017, 204, 35) we show that a photoinduced conductance enhancement can be much stronger than the rather modest enhancement obtained in the aforementioned experiment.
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Affiliation(s)
- Ioan Bâldea
- Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
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15
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Atesci H, Kaliginedi V, Celis Gil JA, Ozawa H, Thijssen JM, Broekmann P, Haga MA, van der Molen SJ. Humidity-controlled rectification switching in ruthenium-complex molecular junctions. NATURE NANOTECHNOLOGY 2018; 13:117-121. [PMID: 29203913 DOI: 10.1038/s41565-017-0016-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/13/2017] [Indexed: 05/09/2023]
Abstract
Although molecular rectifiers were proposed over four decades ago 1,2 , until recently reported rectification ratios (RR) were rather moderate 2-11 (RR ~ 101). This ceiling was convincingly broken using a eutectic GaIn top contact 12 to probe molecular monolayers of coupled ferrocene groups (RR ~ 105), as well as using scanning tunnelling microscopy-break junctions 13-16 and mechanically controlled break junctions 17 to probe single molecules (RR ~ 102-103). Here, we demonstrate a device based on a molecular monolayer in which the RR can be switched by more than three orders of magnitude (between RR ~ 100 and RR ≥ 103) in response to humidity. As the relative humidity is toggled between 5% and 60%, the current-voltage (I-V) characteristics of a monolayer of di-nuclear Ru-complex molecules reversibly change from symmetric to strongly asymmetric (diode-like). Key to this behaviour is the presence of two localized molecular orbitals in series, which are nearly degenerate in dry circumstances but become misaligned under high humidity conditions, due to the displacement of counter ions (PF6-). This asymmetric gating of the two relevant localized molecular orbital levels results in humidity-controlled diode-like behaviour.
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Affiliation(s)
- Huseyin Atesci
- Huygens-Kamerlingh Onnes Laboratorium, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands
| | - Veerabhadrarao Kaliginedi
- Huygens-Kamerlingh Onnes Laboratorium, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland.
| | - Jose A Celis Gil
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Hiroaki Ozawa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, 112-8551, Japan
| | - Joseph M Thijssen
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Peter Broekmann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland
| | - Masa-Aki Haga
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, 112-8551, Japan
| | - Sense Jan van der Molen
- Huygens-Kamerlingh Onnes Laboratorium, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
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16
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Katano S, Wei T, Sasajima T, Kasama R, Uehara Y. Localized electronic structures of graphene oxide studied using scanning tunneling microscopy and spectroscopy. Phys Chem Chem Phys 2018; 20:17977-17982. [DOI: 10.1039/c8cp01168k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Scanning tunneling microscopy (STM) has been used to elucidate the nanoscale electronic structures of graphene oxide (GO).
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Affiliation(s)
- Satoshi Katano
- Research Institute of Electrical Communication
- Tohoku University
- Sendai 980-8577
- Japan
| | - Tao Wei
- Research Institute of Electrical Communication
- Tohoku University
- Sendai 980-8577
- Japan
| | - Takumi Sasajima
- Research Institute of Electrical Communication
- Tohoku University
- Sendai 980-8577
- Japan
| | - Ryuhei Kasama
- Research Institute of Electrical Communication
- Tohoku University
- Sendai 980-8577
- Japan
| | - Yoichi Uehara
- Research Institute of Electrical Communication
- Tohoku University
- Sendai 980-8577
- Japan
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17
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Cocchi C, Draxl C. Understanding the effects of packing and chemical terminations on the optical excitations of azobenzene-functionalized self-assembled monolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:394005. [PMID: 28664870 DOI: 10.1088/1361-648x/aa7ca7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In a first-principles study based on many-body perturbation theory, we analyze the optical excitations of azobenzene-functionalized self-assembled monolayers (SAMs) with increasing packing density and different terminations, considering for comparison the corresponding gas-phase molecules and dimers. Intermolecular coupling increases with the density of the chromophores independently of the functional groups. The intense [Formula: see text] resonance that triggers photo-isomerization is present in the spectra of isolated dimers and diluted SAMs, but it is almost completely washed out in tightly packed architectures. Intermolecular coupling is partially inhibited by mixing differently functionalized azobenzene derivatives, in particular when large groups are involved. In this way, the excitation band inducing the photo-isomerization process is partially preserved and the effects of dense packing partly counterbalanced. Our results suggest that a tailored design of azobenzene-functionalized SAMs which optimizes the interplay between the packing density of the chromophores and their termination can lead to significant improvements in the photo-switching efficiency of these systems.
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Affiliation(s)
- Caterina Cocchi
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany. European Theoretical Spectroscopic Facility (ETSF
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18
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Volkov PA, Petrushenko KB, Ivanova NI, Khrapova KO, Larina LI, Gusarova NK, Trofimov BA. Oxidative coupling of hydroxy- or aminoazobenzenes with secondary phosphine chalcogenides: Towards new media-responsive molecular switches. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.04.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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19
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Zhang L, Huang J, Wang W, Li Q, Yang J. Transport properties of a three-shell icosahedral matryoshka cluster: a first-principles study. RSC Adv 2017. [DOI: 10.1039/c7ra01003f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The molecular junction based on three-shell icosahedral matryoshka cluster with huge magnetic moment exhibits robust spin-filtering effect, which highlights it for promising applications in molecular devices.
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Affiliation(s)
- Lu Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
- China
| | - Jing Huang
- School of Materials and Chemical Engineering
- Anhui Jianzhu University
- Hefei
- China
| | - Weiyi Wang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
- China
| | - Qunxiang Li
- Hefei National Laboratory for Physical Sciences at the Microscale
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
- China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
- China
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20
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Piosik E, Kotkowiak M, Korbecka I, Galewski Z, Martyński T. Photo-switching of a non-ionic azobenzene amphiphile in Langmuir and Langmuir–Blodgett films. Phys Chem Chem Phys 2017; 19:23386-23396. [DOI: 10.1039/c7cp03514d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The concept of programmable and reconfigurable soft matter has emerged in science in the last few decades and can be realized by photoisomerization of azobenzene derivatives.
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Affiliation(s)
- Emilia Piosik
- Faculty of Technical Physics
- Poznan University of Technology
- 60-965 Poznań
- Poland
| | - Michał Kotkowiak
- Faculty of Technical Physics
- Poznan University of Technology
- 60-965 Poznań
- Poland
| | | | | | - Tomasz Martyński
- Faculty of Technical Physics
- Poznan University of Technology
- 60-965 Poznań
- Poland
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21
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Cocchi C, Moldt T, Gahl C, Weinelt M, Draxl C. Optical properties of azobenzene-functionalized self-assembled monolayers: Intermolecular coupling and many-body interactions. J Chem Phys 2016; 145:234701. [DOI: 10.1063/1.4971436] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Caterina Cocchi
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- European Theoretical Spectroscopic Facility (ETSF)
| | - Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Cornelius Gahl
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Claudia Draxl
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- European Theoretical Spectroscopic Facility (ETSF)
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22
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Yao H, Shiratsu T. Individual and collective modes of surface magnetoplasmon in thiolate-protected silver nanoparticles studied by MCD spectroscopy. NANOSCALE 2016; 8:11264-11274. [PMID: 27188783 DOI: 10.1039/c6nr00631k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiol (DT)-, azobenzenethiol (ABT)-, and ABT/DT mixed-monolayer-protected Ag nanoparticles. ABT-protected Ag nanoparticles are somewhat aggregated and thus exhibit a broad, collective mode of plasmonic absorption, whereas other samples with highly-dispersed nanoparticles show an individual mode of LSPR absorption. In all Ag nanoparticles, a derivative-like MCD signal is observed under an applied magnetic field of 1.6 T, which can be explained in terms of two circular modes of magnetoplasmon caused by the increase (or decrease) in the Lorentz force imparted on the free electrons that oscillate in the left (or right) circular orbits in the nanosphere. For the Ag nanoparticles exhibiting an individual LSPR mode, in particular, simultaneous deconvolution analysis of UV-vis absorption and MCD spectra reveal that (i) the amplitude of the magnetoplasmonic component with lower frequency (ω-), resulting from the reduction in the confinement strength of collective electrons by the Lorentz force, is stronger than that with a higher frequency (ω+); (ii) the accurate shift or cyclotron frequency between two magnetoplasmonic modes (ωc = ω+-ω-) is size-dependent, and presents a very large value with implications for the apparent enhancement of the local magnetic-field in the Ag nanoparticles. These results strongly suggest that the Ag-thiolate layer or Ag-S bonding on the nanoparticle surface plays a significant role in the MO enhancement.
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Affiliation(s)
- Hiroshi Yao
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
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23
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Nakamura M, Yoshida S, Katayama T, Taninaka A, Mera Y, Okada S, Takeuchi O, Shigekawa H. Mechanically activated switching of Si-based single-molecule junction as imaged with three-dimensional dynamic probe. Nat Commun 2015; 6:8465. [PMID: 26439280 PMCID: PMC5426520 DOI: 10.1038/ncomms9465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/24/2015] [Indexed: 01/26/2023] Open
Abstract
Understanding and extracting the full functions of single-molecule characteristics are key factors in the development of future device technologies, as well as in basic research on molecular electronics. Here we report a new methodology for realizing a three-dimensional (3D) dynamic probe of single-molecule conductance, which enables the elaborate 3D analysis of the conformational effect on molecular electronics, by the formation of a Si/single molecule/Si structure using scanning tunnelling microscopy (STM). The formation of robust covalent bonds between a molecule and Si electrodes, together with STM-related techniques, enables the stable and repeated control of the conformational modulation of the molecule. By 3D imaging of the conformational effect on a 1,4-diethynylbenzene molecule, a binary change in conductance with hysteresis is observed for the first time, which is considered to originate from a mechanically activated conformational change. Mechanically induced conformational modulation can be used to control the conductance of single molecules junctions, but it is hard to be realized due to broken junctions. Here, the authors probe three-dimensional dynamics of Si/single-molecule/Si junctions, whose conductance shows a binary change.
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Affiliation(s)
- Miki Nakamura
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Shoji Yoshida
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Tomoki Katayama
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Atsushi Taninaka
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Yutaka Mera
- Shiga University of Medical Science, Shiga 520-2122, Japan
| | - Susumu Okada
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Osamu Takeuchi
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Hidemi Shigekawa
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
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24
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Jothi M, Kumaradhas P. Probing the effect of electric field in 9,10-dimethoxy-2,6-bis(2- p-tolylethynyl)anthracene molecular nanowire using quantum chemical and charge density analysis. MOLECULAR SIMULATION 2015. [DOI: 10.1080/08927022.2013.879471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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25
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Liu Y, Yang W, Liu H. Azobenzene-Functionalized Cage Silsesquioxanes as Inorganic-Organic Hybrid, Photoresponsive, Nanoscale, Building Blocks. Chemistry 2015; 21:4731-8. [DOI: 10.1002/chem.201406142] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Indexed: 11/08/2022]
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26
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Ivan LM, Closca V, Burlea M, Rusu E, Airinei A, Dorohoi DO. About intermolecular interactions in binary and ternary solutions of some azo-benzene derivatives. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 136:2008-2014. [PMID: 25168003 DOI: 10.1016/j.saa.2014.07.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 07/28/2014] [Accepted: 07/30/2014] [Indexed: 06/03/2023]
Abstract
The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (ADi, i=1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet-Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute-solvent molecular pairs were obtained analyzing the ternary solutions of ADi, i=1, 2, 3 compounds in solvent mixture Methanol (M)+n-Hexane (H).
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Affiliation(s)
- Liliana Mihaela Ivan
- Faculty of Physics, Alexandru Ioan Cuza University, 11 Carol I Bvd., Iasi RO-700506, Romania
| | - Valentina Closca
- Faculty of Physics, Alexandru Ioan Cuza University, 11 Carol I Bvd., Iasi RO-700506, Romania
| | - Marin Burlea
- "Gr.T. Popa" University of Medicine and Pharmacy, Faculty of Medicine, 16 University Street, 700115 Iasi, Romania
| | - Elena Rusu
- ''Petru Poni" Institute of Macromolecular Chemistry, 41 A, Aleea Grigore Ghica Voda, Iasi RO-700487, Romania
| | - Anton Airinei
- ''Petru Poni" Institute of Macromolecular Chemistry, 41 A, Aleea Grigore Ghica Voda, Iasi RO-700487, Romania
| | - Dana Ortansa Dorohoi
- Faculty of Physics, Alexandru Ioan Cuza University, 11 Carol I Bvd., Iasi RO-700506, Romania
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27
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Kundu PK, Klajn R. Watching single molecules move in response to light. ACS NANO 2014; 8:11913-11916. [PMID: 25474733 DOI: 10.1021/nn506656r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nature has long inspired scientists with its seemingly unlimited ability to harness solar energy and to utilize it to drive various physiological processes. With the help of man-made molecular photoswitches, we now have the potential to outperform natural systems in many ways, with the ultimate goal of fabricating multifunctional materials that operate at different light wavelengths. An important challenge in developing light-controlled artificial molecular machines lies in attaining a detailed understanding of the photoisomerization-coupled conformational changes that occur in macromolecules and molecular assemblies. In this issue of ACS Nano, Bléger, Rabe, and co-workers use force microscopy to provide interesting insights into the behavior of individual photoresponsive molecules and to identify contraction, extension, and crawling events accompanying light-induced isomerization.
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Affiliation(s)
- Pintu K Kundu
- Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel
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28
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Snegir SV, Yu P, Maurel F, Kapitanchuk OL, Marchenko AA, Lacaze E. Switching at the nanoscale: light- and STM-tip-induced switch of a thiolated diarylethene self-assembly on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13556-13563. [PMID: 25264847 DOI: 10.1021/la5029806] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The light-induced and STM-tip-induced switching of photochromic thiol functionalized terphenylthiazole-based diarylethene self-assembly on Au(111) has been investigated in ambient conditions. For such a purpose, we took advantage of the formation of highly ordered domains of opened-ring (1o) or closed-ring (1c) diarylethene isomers. We evidenced a STM-tip-induced switching for the 1o isomer characterized by a tip bias threshold of 1000 mV above which switching of all molecules of the ordered 1o domains occurs into the 1c isomer. In contrast, switching from 1c form into 1o form is not observed at the same tunnelling conditions within a domain formed by ordered 1c molecules. We compared tip-induced switching of ordered 1o domains and switching of single 1o isomers embedded in 1c domains. This led to the demonstration that the process of switching of the 1o isomer is determined by geometry of the molecules but also that the stability of the switched 1c isomer depends on the nature of the surrounding isomers. We also compare tip-induced switching and switching under the action of external UV light irradiation of ordered 1o domains. In contrast with STM tip-induced switching, the UV light induces switching of 1o domains into their stable 1c form, in agreement with a collective switching under irradiation, which cannot occur under the action of STM tip.
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Affiliation(s)
- Sergii V Snegir
- CNRS, UMR 7588, Institut des Nanosciences de Paris, 4 place Jussieu, F-75005, Paris, France
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29
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Liu JJ, Wang Y, Wu ST, Lin MJ, Huang CC, Dai WX. Discrete polynuclear manganese nanorods: syntheses, crystal structures and magnetic properties. RSC Adv 2014. [DOI: 10.1039/c4ra07015a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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30
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Tian Z, Wen J, Ma J. Dynamic simulations of stimuli-responsive switching of azobenzene derivatives in self-assembled monolayers: reactive rotation potential and switching functions. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.918974] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Pipolo S, Corni S. Wettability of azobenzene self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4415-4421. [PMID: 24673397 DOI: 10.1021/la404922f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The wettability properties of azobenzene self-assembled monolayers (SAMs), in the trans and cis forms, are investigated herein by classical Molecular Dynamics simulations of validated assembly structures described with a dedicated force field. The two different methodologies used for the calculation of the contact angle, one based on the Young's equation and the other on geometrical models, have provided a consistent description of the SAMs wettability in line with available experimental results. Furthermore, we provide an atomistic description of the first layers of water molecules at the solvent-SAM interface, which rationalizes the wettability difference between the cis- and trans-SAMs.
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Affiliation(s)
- Silvio Pipolo
- Center S3, CNR Institute of Nanoscience and Department of Physics, University of Modena and Reggio Emilia , Via Campi 213/A, 41125 Modena, Italy
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32
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Nematollahi D, Zohdijamil Z, Salehzadeh H. An efficient electrochemical method for the synthesis of N,N,N′,N′-tetraalkyl-4,4′-azodianiline. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2014.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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33
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Jung U, Kubitschke J, Herges R, Magnussen O. Studies of the molecular switching of azobenzene-functionalized platform adlayers on Au(111) by chronoamperometry. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.06.123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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34
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Nguyen P, Li J, Sreeprasad TS, Jasuja K, Mohanty N, Ikenberry M, Hohn K, Shenoy VB, Berry V. Covalent functionalization of dipole-modulating molecules on trilayer graphene: an avenue for graphene-interfaced molecular machines. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3823-8. [PMID: 23713056 DOI: 10.1002/smll.201300857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Indexed: 05/05/2023]
Abstract
The molecular dipole moment plays a significant role in governing important phenomena like molecular interactions, molecular configuration, and charge transfer, which are important in several electronic, electrochemical, and optoelectronic systems. Here, the effect of the change in the dipole moment of a tethered molecule on the carrier properties of (functionalized) trilayer graphene--a stack of three layers of sp(2)-hybridized carbon atoms--is demonstrated. It is shown that, due to the high carrier confinement and large quantum capacitance, the trans-to-cis isomerisation of 'covalently attached' azobenzene molecules, with a change in dipole moment of 3D, leads to the generation of a high effective gating voltage. Consequently, 6 units of holes are produced per azobenzene molecule (hole density increases by 440 000 holes μm(-2)). Based on Raman and X-ray photoelectron spectroscopy data, a model is outlined for outer-layer, azobenzene-functionalized trilayer graphene with current modulation in the inner sp(2) matrix. Here, 0.097 V are applied by the isomerisation of the functionalized azobenzene. Further, the large measured quantum capacitance of 72.5 μF cm(-2) justifies the large Dirac point in the heavily doped system. The mechanism defining the effect of dipole modulation of covalently tethered molecules on graphene will enable future sensors and molecular-machine interfaces with graphene.
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Affiliation(s)
- Phong Nguyen
- Department of Chemical Engineering, Kansas State University, 66506, USA
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35
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Pijper TC, Kudernac T, Katsonis N, van der Maas M, Feringa BL, van Wees BJ. Reversible light induced conductance switching of asymmetric diarylethenes on gold: surface and electronic studies. NANOSCALE 2013; 5:9277-9282. [PMID: 24163831 DOI: 10.1039/c3nr00832k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on the light-induced switching of conductance of a new generation of diarylethene switches embedded in an insulating matrix of dodecanethiol on Au(111), by using scanning tunneling microscopy (STM). The diarylethene switches we synthesize and study are modified diarylethenes where the thiophene unit at one side of the molecular backbone introduces an intrinsic asymmetry into the switch, which is expected to influence its photo-conductance properties. We show that reversible conversion between two distinguishable conductance states can be controlled via photoisomerisation of the switches by using alternative irradiation with UV (λ = 313 nm) or visible (λ > 420 nm) light. We addressed this phenomenon by using STM in ambient conditions, based on switching of the apparent height of the molecules which convert from 4-6 Å in their closed form to 0-1 Å in their open form. Furthermore, the levels of the frontier molecular orbital levels (HOMO and LUMO) were evaluated for these asymmetric switches by using Scanning Tunneling Spectroscopy at 77 K, which allowed us to determine a HOMO-LUMO energy gap of 2.24 eV.
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36
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Valley DT, Onstott M, Malyk S, Benderskii AV. Steric hindrance of photoswitching in self-assembled monolayers of azobenzene and alkane thiols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11623-11631. [PMID: 23924041 DOI: 10.1021/la402144g] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Surface-bound azobenzenes exhibit reversible photoswitching via trans-cis photoisomerization and have been proposed for a variety of applications such as photowritable optical media, liquid crystal displays, molecular electronics, and smart wetting surfaces. We report a novel synthetic route using simple protection chemistry to form azobenzene-functionalized SAMs on gold and present a mechanistic study of the molecular order, orientation, and conformation in these self-assembled monolayers (SAMs). We use vibrational sum-frequency generation (VSFG) to characterize their vibrational modes, molecular orientation, and photoisomerization kinetics. Trans-cis conformational change of azobenzene leads to the change in the orientation of the nitrile marker group detected by VSFG. Mixed SAMs of azobenzene and alkane thiols are used to investigate the steric hindrance effects. While 100% azobenzene SAMs do not exhibit photoisomerization due to tight packing, we observe reversible switching (>10 cycles) in mixed SAMs with only 34% and 50% of alkane thiol spacers.
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Affiliation(s)
- David T Valley
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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37
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Pipolo S, Benassi E, Corni S. Structural properties of azobenzene self-assembled monolayers by atomistic simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:10505-10512. [PMID: 23879669 DOI: 10.1021/la401645k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Azobenzene self-assembled monolayers (SAMs) are examples of optomechanical nanostructures capable of producing mechanical work through the well-known azobenzene photoisomerization process. Experimental studies have provided information on their structural properties, but an atomistic description of the SAMs in both the cis and trans forms is still lacking. In this work, a computational investigation of the SAM structures is conducted by classical molecular dynamics with a dedicated force. Experimental data on the SAM unit cell is used to set up SAM models of different molecular densities. The optimal structures are identified through the comparison with structural data from X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies. The resulting SAM atomistic models are validated by comparing simulated and experimental scanning tunneling microscopy images.
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Affiliation(s)
- Silvio Pipolo
- Center S3, CNR Institute of Nanoscience, Via Campi 213/A, 41121 Modena, Italy.
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38
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FARMANZADEH DAVOOD, ASHTIANI ZEINAB. MANIPULATING PERFORMANCE OF A MOLECULAR WIRE WITH CHEMICAL MODIFICATION AND EXTERNAL ELECTRIC FIELD. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2013. [DOI: 10.1142/s0219633613500405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this work, a detailed theoretical investigation of the substituent groups effect on the geometric and electronic properties of the newly proposed molecular wire has been performed with the DFT-B3LYP/6-31G* level of theory by considering the influence from the external electric field (EF). The results show that the performance of molecular wire is very sensitive to the electron donating (– NH2 and – OH ), electron withdrawing (– NO2 and – F ) groups and external EF intensities. The energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), ELUMO–EHOMO (HLG) in all cases decreased, furthermore, the electron withdrawing – NO2 group had a much lower HLG than the other substituted groups. Results of this study indicate that the substitutions and external electric field can be used to tune the properties of a molecular scale device effectively.
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Affiliation(s)
- DAVOOD FARMANZADEH
- Department of Physical Chemistry, Faculty of Chemistry, University of Mazandaran, P. O. Box 453, Babolsar, I. R. Iran
| | - ZEINAB ASHTIANI
- Department of Physical Chemistry, Faculty of Chemistry, University of Mazandaran, P. O. Box 453, Babolsar, I. R. Iran
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39
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Ishikawa D, Ito E, Han M, Hara M. Effect of the steric molecular structure of azobenzene on the formation of self-assembled monolayers with a photoswitchable surface morphology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4622-4631. [PMID: 23249363 DOI: 10.1021/la302552v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The growth processes of self-assembled monolayers (SAMs) of two azobenzene disulfides formed on flat gold surfaces were studied to confirm the effect of the intermolecular interactions between azobenzene molecules on the light-triggered surface morphologies of the SAMs. Scanning tunneling microscopy (STM), atomic force microscopy (AFM), thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) absorption spectroscopy were employed to study the SAMs and their growth processes. The SAMs studied were of bulky-substituted azobenzene disulfide (Et-2S), and nonsubstituted azobenzene disulfide (Me-2S), formed on a gold-covered substrate, and had a twisted and a planar structure, respectively. STM-based imaging of the initial stage of the self-assembly of the Et-2S molecules revealed that cleavage of the disulfide bond occurred on the gold surface, and phase-separated domains composed of azobenzenethiolate and dodecanethiolate were formed. Time-dependent AFM-based imaging illustrated the mechanism through which the Et-2S SAM grew-it was through the formation of dendritic aggregates and islands-eventually resulting in phase-separated domains with a wormlike structure. This wormlike structure showed noticeable changes in its surface morphology upon irradiation with UV and visible light. On the other hand, while the growth process for the Me-2S SAM was similar to that of the Et-2S SAM, the final Me-2S SAM had smooth domains whose morphology did not exhibit photoswitchability. The TD and XP spectra of the SAMs showed that the number of adsorbed Et-2S molecules reached a point of saturation after a 24 h long immersion while the number of Me-2S molecules increased even after a 336 h long immersion. Furthermore, the area occupied by the azobenzene moiety in the Et-2S SAM was constant regardless of the immersion time, whereas that in the Me-2S SAM decreased with the immersion time. These results indicated that the strength of the interactions between the azobenzene molecules significantly influenced the aggregate-forming ability in SAMs.
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Affiliation(s)
- Daisuke Ishikawa
- Department of Electronic Chemistry, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8502, Japan
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Enchev V, Monev V, Markova N, Rogozherov M, Angelova S, Spassova M. A model system with intramolecular hydrogen bonding: Effect of external electric field on the tautomeric conversion and electronic structures. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2012.11.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Kim Y, Garcia-Lekue A, Sysoiev D, Frederiksen T, Groth U, Scheer E. Charge transport in azobenzene-based single-molecule junctions. PHYSICAL REVIEW LETTERS 2012; 109:226801. [PMID: 23368145 DOI: 10.1103/physrevlett.109.226801] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Indexed: 05/21/2023]
Abstract
Azobenzene-derivative molecules change their conformation as a result of a cis-trans transition when exposed to ultraviolet or visible light irradiation and this is expected to induce a significant variation in the conductance of molecular devices. Despite extensive investigations carried out on this type of molecule, a detailed understanding of the charge transport for the two isomers is still lacking. We report a combined experimental and theoretical analysis of electron transport through azobenzene-derivative single-molecule break junctions with Au electrodes. Current-voltage and inelastic electron tunneling spectroscopy (IETS) measurements performed at 4.2 K are interpreted based on first-principles calculations of electron transmission and IETS spectra. This qualitative study unravels the origin of a slightly higher conductance of junctions with the cis isomer and demonstrates that IETS spectra of cis and trans forms show distinct vibrational fingerprints that can be used for identifying the isomer.
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Affiliation(s)
- Youngsang Kim
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
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42
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Nguyen TTT, Türp D, Wagner M, Müllen K. Photoswitchable Conductivity in a Rigidly Dendronized Salt. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/anie.201206010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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43
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Nguyen TTT, Türp D, Wagner M, Müllen K. Photoswitchable Conductivity in a Rigidly Dendronized Salt. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Huang T, Zhao J, Feng M, Popov AA, Yang S, Dunsch L, Petek H. A multi-state single-molecule switch actuated by rotation of an encapsulated cluster within a fullerene cage. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.09.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Tegeder P. Optically and thermally induced molecular switching processes at metal surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:394001. [PMID: 22964773 DOI: 10.1088/0953-8984/24/39/394001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using light to control the switching of functional properties of surface-bound species is an attractive strategy for the development of new technologies with possible applications in molecular electronics and functional surfaces and interfaces. Molecular switches are promising systems for such a route, since they possess the ability to undergo reversible changes between different molecular states and accordingly molecular properties by excitation with light or other external stimuli. In this review, recent experiments on photo- and thermally induced molecular switching processes at noble metal surfaces utilizing two-photon photoemission and surface vibrational spectroscopies are reported. The investigated molecular switches can either undergo a trans-cis isomerization or a ring opening-closure reaction. Two approaches concerning the connection of the switches to the surface are applied: physisorbed switches, i.e. molecules in direct contact with the substrate, and surface-decoupled switches incorporated in self-assembled monolayers. Elementary processes in molecular switches at surfaces, such as excitation mechanisms in photoisomerization and kinetic parameters for thermally driven reactions, which are essential for a microscopic understanding of molecular switching at surfaces, are presented. This in turn is needed for designing an appropriate adsorbate-substrate system with the desired switchable functionality controlled by external stimuli.
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Affiliation(s)
- Petra Tegeder
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, D-14195 Berlin, Germany.
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46
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Wang S, Wang W, Lin N. Visualization and manipulation of individual dopant states in single conjugated oligomers. ACS NANO 2012; 6:3404-3410. [PMID: 22397455 DOI: 10.1021/nn300428k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nonlinear excitations associated with dopant states play fundamental roles for charge transport in conjugated polymers. Here we report on real-space visualization of individual dopant states in single conjugated oligomers of poly-para-phenylene using cryogenic scanning tunneling microscopy and spectroscopy. We have found that these states exhibit a typical spatial extension of 4 nm along the oligomers. In particular, these states create a shallow level inside the band gap of the parent oligomers. The origin of these states is traced to a novel doping mechanism of dehydrogenation of the phenylene moiety. Furthermore, we use a scanning tunneling microscope tip to charge/discharge the dopant states and measure their lifetimes. The present results demonstrate a strategy to characterize and manipulate individual dopant states in conjugated polymers with subnanometer resolution.
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Affiliation(s)
- Shiyong Wang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
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Jacquart A, Williams RM, Brouwer AM, Ishow E. Decoupling fluorescence and photochromism in bifunctional azo derivatives for bulk emissive structures. Chemistry 2012; 18:3706-20. [PMID: 22322661 DOI: 10.1002/chem.201103411] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Indexed: 11/08/2022]
Abstract
Bifunctional molecules that combine independent push-pull fluorophores and azo photochromes have been synthesized to create fluorescent structures upon light-induced migration in neat thin films. Their photochromic and emissive properties have been systematically investigated and interpreted in light of those of the corresponding model compounds. Fluorescence lifetimes and photoisomerization and fluorescence quantum yields have been determined in toluene solution. Kinetic analyses of the femtosecond transient absorption spectra reveal that the fluorophores evolve in a few picoseconds into a distorted intramolecular charge-transfer excited state, strongly stabilized in energy. Radiative relaxation to the ground state occurred competitively with the energy-transfer process to the azo moiety. Introduction of a 10 Å-long rigid and nonconjugated bridge between the photoactive units efficiently inhibits the energy transfer while it imparts enhanced free volume, which favors photoactivated molecular migration in the solid state.
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Affiliation(s)
- Aurélie Jacquart
- PPSM-UMR CNRS 8531, ENS Cachan, 61 avenue du Président Wilson, 94235 Cachan cedex, France
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Chapman C, Paci I. Behavior of a chemisorbed azobenzene derivative in an STM environment: A DFT study of charged states and electric fields. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.10.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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49
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Bossi ML, Aramendía PF. Photomodulation of macroscopic properties. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2011. [DOI: 10.1016/j.jphotochemrev.2011.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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50
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Shah SM, Martini C, Ackermann J, Fages F. Photoswitching in azobenzene self-assembled monolayers capped on zinc oxide: nanodots vs nanorods. J Colloid Interface Sci 2011; 367:109-14. [PMID: 22082797 DOI: 10.1016/j.jcis.2011.10.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 09/05/2011] [Accepted: 10/17/2011] [Indexed: 11/29/2022]
Abstract
We report the synthesis and spectroscopic characterization of nanohybrid structures consisting of an azobenzene compound grafted on the surface of zinc oxide nanoparticles. Characteristic bathochromic shifts indicate that the azobenzene photochromic molecules self-assemble onto the surface of the nanocrystals. The extent of packing is dependent on the shape of the nanoparticle. ZnO nanorods, with flat facets, enable a tighter organization of the molecules in the self-assembled monolayer than in the case of nanodots that display a more curvated shape. Consistently, the efficiency of photochromic switching of the self-assembled monolayer on ZnO nanoparticles is also shown to be strongly affected by nanoparticle shape.
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Affiliation(s)
- Syed Mujtaba Shah
- CINaM, UPR 3118 CNRS - Université de la Méditerranée, Campus de Luminy, Case 913, Marseille 13288, France.
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