- Nano Express
- Open Access
Controlling Contact Configuration of Carboxylic Acid-Based Molecular Junctions Through Side Group
Nanoscale Research Letters volume 14, Article number: 253 (2019)
In this paper, the contact configuration of single molecular junction is controlled through side group, which is explored by electrochemical jump-to-contact STM break junction. The conductance values of 2-methoxy-1,3-benzenedicarboxylic acid (2-M-1,3-BDC) is around 10–3.65 G0, which is different from that of 5-methoxy-1,3-benzenedicarboxylic acid (5-M-1,3-BDC) with 10–3.20 G0. Interestingly, the conductance value of 2-M-1,3-BDC is the same as that of 1,3-benzenedicarboxaldehyde (1,3-BDCA), while single molecular junctions of 5-M-1,3-BDC and 1,3-benzenedicarboxylic acid (1,3-BDC) give out similar conductance value. Since 1,3-BDCA binds to the Cu electrode through one oxygen atom, the dominated contact configuration for 1,3-BDC is through two oxygen atoms. The different conductance values between 2-M-1,3-BDC and 5-M-1,3-BDC can be attributed to the different contact configurations caused by the position of the side group. The current work provides a feasible way to control the contact configuration between the anchoring group and the electrode, which may be useful in designing future molecular electronics.
A well understanding of the electron transport through single molecular junctions is a fundamental interest in the development of molecular electronics [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. In recent years, numerous literature have indicated that the single molecular conductance can be influenced by intrinsic molecular structure [10, 15,16,17,18], anchoring groups , contact configurations [20, 21], electrode materials [22,23,24], and so on [4, 14, 25, 26]. Among them, contact configurations play an important role in electron transport of single molecular junctions [27,28,29]. However, there is rather limited report on this issue, because of the difficulty in controlling the contact configuration.
About contact configuration, some experimental works show multiple sets of conductance values for single molecular junctions corresponding to different contact configurations [20, 30]. However, multiple configurations bring complexity and difficulty in the analysis of the single molecular conductance. The ability to control contact configuration between electrodes and anchoring groups is extremely important, for it can exclude the complexity of contact configurations for future molecular electronics. One way to control the contact configurations is mechanical controlling of single-molecule junctions, and conductance values can be switched between low and high values by mechanically switching of the molecule and electrode contact configurations . Such mechanically controlling may still bring different configurations and is difficult to be used in the future molecular electronics. Recently, the adding of side groups are demonstrated to prevent the molecular conductance from switching during mechanical modulation , which shows the possibility of controlling contact configuration through side groups. Therefore, the adding of side groups may provide a feasible way to prevent forming several configurations between molecules and electrodes.
Herein, we choose benzene-based carboxylic acid molecules with various side groups as target molecules to investigate the possible contact configurations in single molecular junctions. The carboxylic acid group has been demonstrated to form single molecular junctions with various electrodes [19, 24, 30, 32]. The target molecules include 2-methoxy-1,3-benzenedicarboxylic acid (2-M-1,3-BDC), 1,3-benzenedicarboxylic acid (1,3-BDC), 5-methoxy-1,3-benzenedicarboxylic acid (5-M-1,3-BDC), and 1,3-benzenedicarboxaldehyde (1,3-BDCA) (Fig. 1). Electrochemical jump-to-contact STM break junction (ECSTM-BJ) is used to construct and measure the single molecular junctions with Cu electrodes (Fig. 1). The Cu electrode is chosen, for it can form more effective molecular junctions with carboxylic acid than Au electrode as reported in our previous works . Especially, electrochemical surrounding can prevent the Cu from oxidation, while the single molecular junctions of the carboxylic acid-based molecule cannot be formed with Cu electrode in the air .
Na2SO4, CuSO4, and 1,3-BDC were purchased from Alfa-Aesar, 2-M-1,3-BDC and 5-M-1,3-BDC were purchased from Sigma-Aldrich, and 1,3-BDCA was obtained from TCI (Tokyo Chemical Industry Co., Ltd.). All of them were used as received. Naturally formed Au (111) on single crystal bead was used as a substrate, while the Pt-Ir insulated by thermosetting polyethylene glue was used as a tip. Pt and Cu wires were used as the counter and reference electrode, respectively.
Conductance measurement of single molecular junctions was carried out on a modified Nanoscope IIIa STM (Veeco, Plainview, NY, USA) and in an aqueous solution containing 1 mM CuSO4 + 50 mM Na2SO4 + 1 mM target molecules. The Pt-Ir tip and Au (111) substrate were set at − 5 and 45 mV versus Cu wire, respectively. In this case, the Cu bulk deposition could occur on the tip but not the substrate. After that, the tip was driven toward the substrate to a sufficiently close distance, and then the jump-to-contact process happened. The tip was pulled away from the substrate at a speed of 20 nm/s. During this process, the conductance trace was recorded till the breaking of single molecular junctions, while Cu clusters were simultaneously produced. Thousands of conductance traces were collected to construct the conductance histogram without data selection. More details for the ECSTM-BJ were reported in our previous works [23, 34, 35].
We carried out the theoretical calculation of the single molecular junction. Standard density functional theory (DFT) method is used to relax the junction structure, where there are 3–4 buffer layers attached to both sides and a large vacuum layer (about 15 Å) inserted outside. Nonequilibrium Green’s function (NEGF) method is adopted to calculate the transport properties, i.e., the transmission coefficients of the junctions at equilibrium [36, 37]. In all the above calculations, Perdew-Burke-Ernzerhof (PBE) functional is used for the exchange-correlation core, and for the sake of both accuracy and efficiency, double-zeta polarized (DZP) basis set is used for organic molecule and the outmost layer of copper atoms and single-zeta polarized (SZP) basis set is used for the other copper layers deep into the electrodes. A (4,4) K-sampling is set along the transverse plane. All the calculations are completed with the open-source package SHINE (Shanghai Integrated Numeric Engineering).
Results and Discussion
Single Molecular Conductance of 2-M-1,3-BDC with the Methoxy Side Group on 2-Position of Molecule
We firstly investigated the single molecular junctions of 2-M-1,3-BDC, which has one methoxy side group on 2-position of 1,3-BDC. The experiment was carried out in an aqueous solution containing 1 mM 2-M-1,3-BDC + 1 mM CuSO4 + 50 mM Na2SO4 by using the ECSTM-BJ approach. Cu clusters were simultaneously produced as a side product (Fig. 2a). Figure 2b displays typical conductance traces in logarithm scale and shows the conductance plateaus of Cu-(2-M-1,3-BDC)-Cu around 10–3.65 G0. Thousands of conductance traces were collected to construct conductance histogram of 2-M-1,3-BDC without data selection in logarithm scale (Fig. 2c). An obvious peak is found around 10–3.65 G0, which is consistent with conductance step in conductance traces. Here, the pronounced peak shows the single molecular conductance with the dominated molecule-electrode contact configuration.
Surprisingly, the conductance value of 2-M-1,3-BDC is obviously different from the conductance of 1,3-BDC. Figure 2d displays the conductance histogram of 1,3-BDC and shows dominated conductance peak forming around 10–3.20 G0, which is similar to a previous report . The methoxy side group cannot bind to the electrode forming effective molecular junctions, thus 2-M-1,3-BDC should bind to the electrode through carboxylic acid anchoring group. The large conductance difference between 2-M-1,3-BDC and 1,3-BDC shows the important role of the methoxy side group on the single-molecule conductance.
The methoxy side group has an effect of pulling electron, which may change the conductance value . However, less than 20% of conductance change is found for molecules with different side groups in the literature (only changing one side group) , while the conductance difference is about 300% between 2-M-1,3-BDC and 1,3-BDC. Thus, only pulling an electron effect of the side group cannot cause such a large conductance difference.
Single Molecular Conductance of 5-M-1,3-BDC with the Methoxy Side Group on the 5-Position of Molecule
In order to further study the important role of the side group, we investigated the single molecular conductance of molecules with methoxy on the 5-position of 1,3-BDC, named 5-M-1,3-BDC. Comparing with 2-M-1,3-BDC, the adding of the side group of methoxy on 5-M-1,3-BDC is away from the anchoring groups.
Figure 3 presents the conductance histograms of 5-M-1,3-BDC, constructing from more than 1000 conductance traces. Comparing with the conductance of 2-M-1,3-BDC, conductance histogram of 5-M-1,3-BDC shows a well-distinguished peak around 10–3.20 G0 and gives out the same conductance value as that of 1,3-BDC (10–3.20 G0). This result illustrates that the position of the side group plays a very important role in the single molecular conductance. Though there is the same methoxy group in molecules of 5-M-1,3-BDC and 2-M-1,3-BDC, there are quite different conductance values between them.
The Possible Reason for Different Conductance Values Among 2-M-1,3-BDC and 5-M-1,3-BDC
What is the reason for a large conductance difference between 2-M-1,3-BDC and 5-M-1,3-BDC? The influence of the side group on destructive quantum interference (DQI) effects in meta-benzene-based molecule might cause this phenomenon [39, 40]. Typically, the conductance of meta-benzene-based molecule is more than one order of magnitude lower than that of a para-benzene-based molecule, while there are other backbones between benzene and anchoring group [41,42,43]. The substituent effect was theoretically reported on such meta-benzene molecule with DQI, which can largely tune the electron transport of DQI molecules . However, the conductance of meta-benzene-based molecule (1,3-BDC with 10–3.20 G0) is larger than that of a para-benzene-based molecule (1,4-benzenedicarboxylic acid, 1,4-BDC, with 10–3.40 G0) , showing there is no DQI effect in the 1,3-BDC. DQI is also not found for those molecules having the same backbone but with thiol and amine as anchoring groups .
The carboxylic acid can bind to Cu electrode through carbonyl (one oxygen atom) or carboxylate (two oxygen atoms) form, while the dominated peak is contributed to configuration through two oxygen atoms for 1,4-BDC . Our calculations demonstrate that there is no DQI effect in those molecular junctions with contact configurations of anchoring group contacting to Cu electrodes through two oxygen atoms of carboxylate (Fig. 4). No obvious conductance difference is found between 2-M-1,3-BDC and 5-M-1,3-BDC, and the possible reason of DQI influenced by the position of the side group can be ruled out.
Another possibility is that the different dominated contact configuration is formed due to the adding of methoxy on different positions. It was reported that the carboxylic acid can bind to Cu electrode through one oxygen atom or two oxygen atoms form, while the dominated peak is contributed to configuration through two oxygen atoms for 1,4-BDC . Thus the situation may be similar to 1,3-BDC and 5-M-1,3-BDC, and the conductance value of 10–3.20 G0 might be contributed to the two oxygen atoms (carboxylate) contacting to Cu electrodes. For 2-M-1,3-BDC, the existence of the methoxy side group near the carboxylic acid may prevent single molecular junctions from contacting Cu electrode through two oxygen atoms of carboxylate, and then the conductance value of 10–3.65 G0 is found. Thus, we may attribute the conductance difference between 2-M-1,3-BDC and 1,3-BDC to the different contact configurations, which is caused by the adding of neighboring methoxy side group. This point is further demonstrated by the conductance measurement of 1,3-BDCA with carbonyl group.
The Validation of Contact Configuration for 2-M-1,3-BDC by the Measurement of Single Molecular Junctions of 1,3-BDCA
From above, the neighboring side group has an effect on the single molecular conductance and may influence the contact configuration between carboxylic acid and Cu electrodes. In order to prove this hypothesis, we carried out the conductance measurement of 1,3-BDCA with only carbonyl anchoring group. The carbonyl anchoring group can bind to Cu electrode through one oxygen atom [30, 45]. Figure 5 shows the conductance histogram of 1,3-BDCA with obvious peak located around 10–3.65 G0. Comparing with the conductance histogram of 1,3-BDC, the conductance of 1,3-BDCA shows a smaller conductance value. However, this value is similar to the conductance of 2-M-1,3-BDC, which may show the same dominated contact configuration formed between 1,3-BDCA and 2-M-1,3-BDC. Especially, we still can find a shoulder peak of 10–3.70 G0 near the dominated peak value of 10–3.20 G0 for 1,3-BDC (Fig. 2d). This value (10–3.70 G0) may be explained by the contact configuration through one oxygen of carboxylate between the anchoring group and the electrode, while dominated peak (10–3.20 G0) is caused by two oxygens of carboxylate binding to the electrode. Due to the neighboring side group at 2-position, the carboxylate group of 2-M-1,3-BDC fails to form molecular junctions through two oxygens of carboxylate, and only one oxygen from carboxylate group bonds to the electrode.
The conductance values for all studied molecules are summarized in Table 1. The conductance value of 2-M-1,3-BDC is the same as that of 1,3-BDCA, while single molecular junctions of 5-M-1,3-BDC and 1,3-BDC give out a similar conductance value. Since 1,3-BDCA can only bind to the Cu electrode through one oxygen atom, the dominated contact configuration for 1,3-BDC is found through two oxygen atoms. The above conductance values for different molecules show the solid evidence that different contact configurations are formed between 2-M-1,3-BDC and 5-M-1,3-BDC. The adding of methoxy on a neighboring site of anchoring group may have steric hindrance effect, which may forbid the formation of contacting configuration between carboxylic acid and electrode through two oxygen atoms at one or both ends. The current work shows the ability to control the contact configuration through the position of the side group.
In conclusion, we have measured the single-molecule conductance carboxylic acid-based molecules binding to Cu electrode by using ECSTM-BJ. It is shown that the contact configuration may be controlled by the position of the side group, which can prevent single molecular junctions from contacting Cu electrode through two oxygen atoms of carboxylate for 2-M-1,3-BDC. Such an effect can be invalidated by putting the side group on the 5-position of the molecule (5-M-1,3-BDC). This research provides a feasible way to control the contact configuration between the anchoring group and the electrode, which may be useful in designing future molecular electronics.
Availability of Data and Materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Destructive quantum interference
Electrochemical jump-to-contact STM break junction
Venkataraman L, Klare JE, Nuckolls C, Hybertsen MS, Steigerwald ML (2006) Dependence of single-molecule junction conductance on molecular conformation. Nature 442:904–907
Perrin ML, Burzuri E, van der Zant HSJ (2015) Single-molecule transistors. Chem Soc Rev 44:902–919
Leary E, La Rosa A, Gonzalez MT, Rubio-Bollinger G, Agrait N, Martin N (2015) Incorporating single molecules into electrical circuits. The role of the chemical anchoring group. Chem Soc Rev 44:920–942
Tao NJ (2006) Electron transport in molecular junctions. Nat Nanotechnol 1:173–181
Ulgut B, Abruna HD (2008) Electron transfer through molecules and assemblies at electrode surfaces. Chem Rev 108:2721–2736
Zhang Q, Tao SH, Yi RW, He CH, Zhao CZ, Su WT, Smogunov A, Dappe YJ, Nichols RJ, Yang L (2017) Symmetry effects on atenuation factors in graphene-based molecular junctions. J Phys Chem Lett 8:5987–5992
Aragonès AC, Haworth NL, Darwish N, Ciampi S, Bloomfield NJ, Wallace GG, Diez-Perez I, Coote ML (2016) Electrostatic catalysis of a Diels–Alder reaction. Nature 531:88–91
Yang Y, Liu JY, Feng S, Wen HM, Tian JH, Zheng JT, Schollhorn B, Amatore C, Chen ZN, Tian ZQ (2016) Unexpected current-voltage characteristics of mechanically modulated atomic contacts with the presence of molecular junctions in an electrochemically assisted-MCBJ. Nano Res 9:560–570
Zheng J-T, Yan R-W, Tian J-H, Liu J-Y, Pei L-Q, Wu D-Y, Dai K, Yang Y, Jin S, Hong W, Tian Z-Q (2016) Electrochemically assisted mechanically controllable break junction studies on the stacking configurations of oligo (phenylene ethynylene) s molecular junctions. Electrochim Acta 200:268–275
Sebechlebska T, Sebera J, Kolivoska V, Lindner M, Gasior J, Meszaros G, Valasek M, Mayor M, Hromadova M (2017) Investigation of the geometrical arrangement and single molecule charge transport in self-assembled monolayers of molecular towers based on tetraphenylmethane tripod. Electrochim Acta 258:1191–1200
Zhang Y-P, Chen L-C, Zhang Z-Q, Cao J-J, Tang C, Liu J, Duan L-L, Huo Y, Shao X, Hong W, Zhang H-L (2018) Distinguishing diketopyrrolopyrrole isomers in single-molecule junctions via reversible stimuli-responsive quantum interference. J Am Chem Soc 140:6531–6535
Leary E, Limburg B, Alanazy A, Sangtarash S, Grace I, Swada K, Esdaile LJ, Noori M, González MT, Rubio-Bollinger G et al (2018) Bias-driven conductance increase with length in porphyrin tapes. J Am Chem Soc 140:12877–12883
Zheng JT, Liu JY, Zhuo YJ, Li RH, Jin X, Yang Y, Chen ZB, Shi J, Xiao ZY, Hong WJ, Tian ZQ (2018) Electrical and SERS detection of disulfide-mediated dimerization in single-molecule benzene-1,4-dithiol junctions. Chem Sci 9:5033–5038
Xiang D, Wang X, Jia C, Lee T, Guo X (2016) Molecular-scale electronics: from concept to function. Chem Rev 116:4318–4440
Kaliginedi V, Moreno-García P, Valkenier H, Hong W, García-Suárez VM, Buiter P, Otten JLH, Hummelen JC, Lambert CJ, Wandlowski T (2012) Correlations between molecular structure and single-junction conductance: a case study with oligo (phenylene-ethynylene)-type wires. J Am Chem Soc 134:5262–5275
Huang C, Jevric M, Borges A, Olsen ST, Hamill JM, Zheng J-T, Yang Y, Rudnev A, Baghernejad M, Broekmann P et al (2017) Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique. Nat Commun 8:15436
Fujii S, Marques-Gonzalez S, Shin JY, Shinokubo H, Masuda T, Nishino T, Arasu NP, Vazquez H, Kiguchi M (2017) Highly-conducting molecular circuits based on antiaromaticity. Nat Commun 8:15984
Arroyo CR, Frisenda R, Moth-Poulsen K, Seldenthuis JS, Bjornholm T, van der Zant HSJ (2013) Quantum interference effects at room temperature in OPV-based single-molecule junctions. Nanoscale Res Lett 8:1–6
Chen F, Li XL, Hihath J, Huang ZF, Tao NJ (2006) Effect of anchoring groups on single-molecule conductance: comparative study of thiol-, amine-, and carboxylic-acid-terminated molecules. J Am Chem Soc 128:15874–15881
Li C, Pobelov I, Wandlowski T, Bagrets A, Arnold A, Evers F (2008) Charge transport in single Au| alkanedithiol| Au junctions: coordination geometries and conformational degrees of freedom. J Am Chem Soc 130:318–326
Müller K-H (2006) Effect of the atomic configuration of gold electrodes on the electrical conduction of alkanedithiol molecules. Phys Rev B 73:045403
Kim T, Vázquez H, Hybertsen MS, Venkataraman L (2013) Conductance of molecular junctions formed with silver electrodes. Nano Lett 13:3358–3364
Zhou XS, Wei YM, Liu L, Chen ZB, Tang J, Mao BW (2008) Extending the capability of STM break junction for conductance measurement of atomic-size nanowires: an electrochemical strategy. J Am Chem Soc 130:13228–13230
Wang YH, Li DF, Hong ZW, Liang JH, Han D, Zheng JF, Niu ZJ, Mao BW, Zhou XS (2014) Conductance of alkyl-based molecules with one, two and three chains measured by electrochemical STM break junction. Electrochem Commun 45:83–86
Darwish N, Díez-Pérez I, Guo S, Tao N, Gooding JJ, Paddon-Row MN (2012) Single molecular switches: electrochemical gating of a single anthraquinone-based norbornylogous bridge molecule. J Phys Chem C 116:21093–21097
Borges A, Xia JL, Hua S, Venkataraman L, Solomon GC (2017) The role of through-space interactions in modulating constructive and destructive interference effects in benzene. Nano Lett 17:4436–4442
Kim YH, Kim HS, Lee J, Tsutsui M, Kawai T (2017) Stretching-induced conductance variations as fingerprints of contact configurations in single-molecule junctions. J Am Chem Soc 139:8286–8294
Ismael AK, Wang K, Vezzoli A, Al-Khaykanee MK, Gallagher HE, Grace IM, Lambert CJ, Xu B, Nichols RJ, Higgins SJ (2017) Side-group-mediated mechanical conductance switching in molecular junctions. Angew Chem Int Ed 56:15378–15382
Li XL, He J, Hihath J, Xu BQ, Lindsay SM, Tao NJ (2006) Conductance of single alkanedithiols: conduction mechanism and effect of molecule-electrode contacts. J Am Chem Soc 128:2135–2141
Hong ZW, Chen F, Wang YH, Mao JC, Li DF, Tang Y, Shao Y, Niu ZJ, Zhou XS (2015) The binding sites of carboxylic acid group contacting to Cu electrode. Electrochem Commun 59:48–51
Quek SY, Kamenetska M, Steigerwald ML, Choi HJ, Louie SG, Hybertsen MS, Neaton JB, Venkataraman L (2009) Mechanically controlled binary conductance switching of a single-molecule junction. Nat Nanotechnol 4:230–234
Martin S, Haiss W, Higgins S, Cea P, Lopez MC, Nichols RJ (2008) A comprehensive study of the single molecule conductance of α,ω-dicarboxylic acid-terminated alkanes. J Phys Chem C 112:3941–3948
Wang YH, Hong ZW, Sun YY, Li DF, Han D, Zheng JF, Niu ZJ, Zhou XS (2014) Tunneling decay constant of alkanedicarboxylic acids: different dependence on the metal electrodes between air and electrochemistry. J Phys Chem C 118:18756–18761
Peng ZL, Chen ZB, Zhou XY, Sun YY, Liang JH, Niu ZJ, Zhou XS, Mao BW (2012) Single molecule conductance of carboxylic acids contacting Ag and Cu electrodes. J Phys Chem C 116:21699–21705
Hong ZW, Ben Aissa MA, Peng LL, Xie HJ, Chen DL, Zheng JF, Shao Y, Zhou XS, Raouafi N, Niu ZJ (2016) Quantum interference effect of single-molecule conductance influenced by insertion of different alkyl length. Electrochem Commun 68:86–89
Chen JZ, Thygesen KS, Jacobsen KW (2012) Ab initio nonequilibrium quantum transport and forces with the real-space projector augmented wave method. Phys Rev B 85:155140
Taylor J, Guo H, Wang J (2001) Ab initio modeling of quantum transport properties of molecular electronic devices. Phys Rev B 63:245407
Venkataraman L, Park YS, Whalley AC, Nuckolls C, Hybertsen MS, Steigerwald ML (2007) Electronics and chemistry: varying single-molecule junction conductance using chemical substituents. Nano Lett 7:502–506
Liu J, Huang X, Wang F, Hong W (2018) Quantum interference effects in charge transport through single-molecule junctions: detection, manipulation, and application. Acc Chem Res 52:151–160
Garner MH, Solomon GC, Strange M (2016) Tuning conductance in aromatic molecules: constructive and counteractive substituent effects. J Phyc Chem C 120:9097–9103
Huang B, Liu X, Yuan Y, Hong ZW, Zheng JF, Pei LQ, Shao Y, Li JF, Zhou XS, Chen J et al (2018) Controlling and observing of sharp-valleyed quantum interference effect in single molecular junctions. J Am Chem Soc 140:17685–17690
Manrique DZ, Huang C, Baghernejad M, Zhao X, Al-Owaedi OA, Sadeghi H, Kaliginedi V, Hong W, Gulcur M, Wandlowski T et al (2015) A quantum circuit rule for interference effects in single-molecule electrical junctions. Nat Commun 6:6389
Arroyo CR, Tarkuc S, Frisenda R, Seldenthuis JS, Woerde CHM, Eelkema R, Grozema FC, van der Zant HSJ (2013) Signatures of quantum interference effects on charge transport through a single benzene ring. Angew Chem Int Ed 52:3152–3155
Kiguchi M, Nakamura H, Takahashi Y, Takahashi T, Ohto T (2010) Effect of anchoring group position on formation and conductance of a single disubstituted benzene molecule bridging Au electrodes: change of conductive molecular orbital and electron pathway. J Phys Chem C 114:22254–22261
Peng LL, Chen F, Hong ZW, Zheng JF, Fillaud L, Yuan Y, Huang ML, Shao Y, Zhou XS, Chen JZ, Maisonhaute E (2018) Precise tuning of single molecule conductance in an electrochemical environment. Nanoscale 10:7026–7032
This research was funded by the National Natural Science Foundation of China (Nos. 21872126, 21573198, and 11404206), the Planned Science and Technology Project of Zhejiang Province (No. 2018C37048), the Open Research Fund of Key Laboratory of the Ministry of Education for Advanced Catalysis Materials and Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Zhejiang Normal University, and the Program for Associate Professor of Special Appointment (Young Eastern Scholar) at Shanghai Institutions of Higher Learning.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Huang, J., Huang, H., Tao, C. et al. Controlling Contact Configuration of Carboxylic Acid-Based Molecular Junctions Through Side Group. Nanoscale Res Lett 14, 253 (2019). https://doi.org/10.1186/s11671-019-3087-7
- Carboxylic acid
- Scanning tunneling microscopy break junction
- Contact configuration