One key issue for the development of molecular electronic devices is to understand the electron transport of single- molecule junctions. In this work, we explore the electron transport of iodine-terminated alkane single molecular junctions using the scanning tunneling microscope-based break junction approach. The result shows that the conductance decreases −1 exponentially with the increase of molecular length with a decay constant β =0.5 per –CH (or 4 nm ). Importantly, the N 2 tunneling decay of those molecular junctions is much lower than that of alkane molecules with thiol, amine, and carboxylic acid as the anchoring groups and even comparable to that of the conjugated oligophenyl molecules. The low tunneling decay is attributed to the small barrier height between iodine-terminated alkane molecule and Au, which is well supported by DFT calculations. The work suggests that the tunneling decay can be effectively tuned by the anchoring group, which may guide the manufacturing of molecular wires. Keywords: Electron transport, Barrier height, Single molecular junction, Iodine, Alkyl-based molecules Background possible to tune the molecular energy level towards the Understanding the electron transport of single-molecule Fermi level to achieve the low decay [21–24]. junctions is crucial for the development of molecular In single-molecule junctions, the anchoring group electronic devices [1–16]. The non-resonant tunneling plays an important role in the control of electronic model has often been used to describe the electron coupling between the organic backbones with the transport process through small molecule, where contact electrodes [21, 23–25]. A series of conductance mea- conductance, molecular length, and the tunneling decay surements for the alkane-based molecules have showed constant are the main parameters [17, 18]. In most mo- a significant effect of different anchoring groups on the lecular systems, decay constant is highly related to the binding geometry, junction formation probabilities, con- electronic properties of organic backbone. For example, tact conductance, and even conductance channel the conjugated molecular systems have low tunneling (through LUMO or HOMO) of molecular junctions decay, unlike non-conjugated ones [17, 19]. Since the [21–25]. Since the anchoring group can regulate the tunneling decay is decided by the barrier height between frontier orbitals in the molecular junction, the tunneling the Fermi level of electrode and lowest unoccupied mo- decay of the molecule may also be tuned by the ancho- lecular orbital (LUMO) or highest occupied molecular ring group . However, limited study has been orbital (HOMO) of molecular junctions [17, 20], it is focused on this area. Herein, we report the electron transport of alkane molecules terminated with iodine group by using scanning tunneling microscopy break junction (STM- * Correspondence: email@example.com; firstname.lastname@example.org; BJ) (Fig. 1)[26, 27]. The single molecular con- email@example.com ductance measurements show that the conductance Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, decreases exponentially with the increase of molecular Zhejiang, China lengths and the decay constant of alkane molecules Department of Applied Chemistry, Zhejiang Gongshang University, with iodine group is much lower than that of the Hangzhou 310018, China Shanghai Key Laboratory of Materials Protection and Advanced Materials in analogues with other anchoring groups. The different Electric Power, Shanghai University of Electric Power, Shanghai 200090, China © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Peng et al. Nanoscale Research Letters (2018) 13:121 Page 2 of 6 repeatedly moving the tip into and out of the substrate at a constant speed. During the process, the molecules could anchor between the two metal electrodes and form single molecular junctions. Thousands of such curves were collected for statistical analysis. All the experiments were performed with a fix bias voltage of 100 mV. Since molecules with iodine as the anchoring group are a photosensitive material, the experiment was carried out under shading. Results and Discussion Conductance Measurement of Iodine-Terminated Alkane Single Molecular Junctions The conductance measurements were first carried out Fig. 1 Schematic diagram of scanning tunneling microscopy on Au(111) with monolayer of 1,4-butanediiodo by break junction (STM-BJ) and molecular structures. a Schematic of the STM-BJ with molecular junction. b Molecular structures of STM-BJ. Figure 2a gives out the typical conductance alkane iodine molecules traces exhibiting the stepwise feature. Conductance traces show plateau at 1 G , indicating the formation of stable Au atomic contact. Plateau at a conductance value −3.6 tunneling decay constants for alkane molecules with of 10 G (19.47 ns) is also found besides the 1 G , 0 0 varied anchoring groups are explained by barrier owing to the formation of molecular junction. A height between molecule and electrode. conductance histogram could also be obtained by treating with logarithm and binning of conductance Methods value from more than 3000 conductance traces, and 1,4-Butanediiodo, 1,5-pentanediiodo, and 1,6-hexane- then, the intensity of conductance histogram was diiodo were purchased from Alfa Aesar. All solutions normalized by the number of traces used and shows a −3.6 were prepared with ethanol. Au(111) was used as the conductance peak at 10 G (19.44 ns) (Fig. 2b). Those substrate, while mechanically cut Au tips were used as show that the iodine group can serve as an effective the tips. Before each experiment, the Au(111) was anchoring group forming molecular junction. However, electrochemically polished and carefully annealed in a this value is smaller than the single molecular butane flame and then dried with nitrogen. conductance value of 1,4-butanediamine with amine as The Au(111) substrate was immersed into a freshly the anchoring group, which may stem from weak prepared ethanol solution containing 0.1 mM target interaction between iodine and Au electrode . molecules for 10 min. The conductance measurement In comparison with 1,4-diiodobutane, pronounced −3.8 −4.0 was carried out on the modified Nanoscope IIIa STM peaks at 10 G (12.28 ns) and 10 G (7.75 ns) are 0 0 (Veeco, USA.) by using the STM-BJ method at room found for 1,5-pentanediiodo and 1,6-hexanediiodo, temperature [28–30], which simply measured the con- respectively (Fig. 3). The conductance values decrease ductance of single-molecule junctions formed by with the increasing of molecule length. Meanwhile, the Fig. 2 Single molecular conductance of Au–1,4-butanediiodo–Au junctions. a Typical conductance curves of Au–1,4-butanediiodo–Au junctions measured at a bias of 100 mV. b Log-scale conductance histogram of 1,4-butanediiodo junctions with Au contacts Peng et al. Nanoscale Research Letters (2018) 13:121 Page 3 of 6 Fig. 3 Single molecular conductance of 1,5-pentanediiodo and 1,6-hexanediiodo with Au electrode. Log-scale conductance histogram of single molecular junctions with a 1,5-pentanediiodo and b 1,6-hexanediiodo conductance values of 1,5-pentanediiodo and 1,6- distances are comparable to the length of molecules. hexanediiodo are smaller than those of 1,5- Eder et al. reported that the adsorption of 1,3,5-tri pentanediamine and 1,6-hexanediamine, respectively (4-iodophenyl)-benzene monolayer onto Au(111) may , which may be caused by the different interaction in cause partial dehalogenation ; however, a very alkane-based molecular junctions between iodine and larger conductance value for those Au–C covalent amine anchoring groups binding to Au electrodes . contact molecular junctions can be found for −1 The two-dimensional conductance histograms were also molecules with four (around 10 G )and six (bigger −2 constructed for those molecular junctions (Additional file 1: than 10 G ) –CH – units . Thus, we propose 0 2 Figure S1) and give out similar conductance values of that the current investigated molecules contact to the one-dimensional histograms. Typically, the breaking off Au through the Au–I contact. distance of molecular junctions increases with the increas- ing of molecular length. We also analyze the distance from Tunneling Decay Constant of Iodine-Terminated Alkane −5.0 −0.3 the conductance value of 10 G to 10 G as shown Single Molecular Junctions 0 0 in Fig. 4, and rupture distances of 0.1, 0.2, and 0.3 nm are Under the current bias, those molecule conductance can found for 1,4-butanediiodo, 1,5-pentanediiodo, and 1,6- be expressed as G = Gc exp(–β N). Here, G is the hexanediiodo, respectively. Here, the rupture distances are conductance of the molecule and Gc is the contact con- obtained from the maximum peak of the rupture distance ductance and is determined by the interaction between histogram . It was reported that there is a snap back the anchoring group and the electrode. N is the methy- distance of 0.5 nm for Au after the breaking of Au–Au lene number in the molecule, and β is the tunneling contact [34, 35]; thus, the absolute distances for those decay constant, which reflects the coupling efficiency of molecular junctions between electrodes could be 0.6, 0.7, electron transport between the molecule and the elec- and 0.8 nm which are found for 1,4-butanediiodo, 1,5- trode. As show in Fig. 5, we plot a natural logarithm pentanediiodo, and 1,6-hexanediiodo, respectively. Those scale of conductance against the number of methylene; Fig. 4 Breaking off distances for iodine-terminated alkanes. Breaking off distances of a 1,4-butanediiodo, b 1,5-pentanediiodo, and c 1,6-hexane- −5.0 −0.3 diiodo obtained from conductance curves between 10 G and 10 G 0 0 Peng et al. Nanoscale Research Letters (2018) 13:121 Page 4 of 6 Additional file 1) to investigate the frontier molecular orbitals of complexes with four Au atoms at the both ends, including 1,6-hexanedithiol (C6DT), 1,6-hexane- diamineb (C6DA), 1,6-hexanedicarboxylic acid (C6DC), and 1,6-hexanediiodo (C6DI). As shown in Table 1, the HOMO and LUMO are − 6.18 and − 1.99 eV, respect- ively, for C6DT, while HOMO (6.02 eV) and LUMO (− 1.85 eV) are found for C6DA. Meanwhile, HOMO and LUMO energy levels are calculated for C6DC (-6.33 and -2.58 eV) and C6DI (-6.22 and -2.61 eV). For the Fermi level of Au electrode, we need to con- sider the influence of the adsorption of molecules. In the vacuum condition, clean Au gives out work function of 5.1 eV ; meanwhile, this value can be obviously changed by the adsorption of molecules. Kim et al.  and Yuan et al.  have found that the work function Fig. 5 Single-molecule conductance vs molecular length for of Au is around 4.2 eV (4.0–4.4 eV) upon the adsorbed iodine-terminated alkanes. Logarithmic plots of single-molecule self-assembled monolayers (SAMs) measured by the conductance vs molecular length for iodine-terminated alkanes ultraviolet photoelectron spectrometer (UPS). Low et al. also investigated the electron transport of thiophene- tunneling decay constant β of 0.5 per –CH is deter- based molecules of TOTOT (LUMO − 3.3 eV, HOMO N 2 mined from the slope of linear fitting. This tunneling − 5.2 eV) and TTO TT (LUMO − 3.6 eV, HOMO − 5. decay is very low in alkane-based molecules. For the 1 eV) with Au as the electrode (T, O, and O denote alkane-based molecules, β is usually found around 1.0 thiophene, thiophene-1,1-dioxide, and oxidized thieno- per –CH for thiol (SH) [23, 38], while around 0.9 and pyrrolodione, respectively) . The results show that 0.8 per –CH are determined for amine (NH )[23, 31] the Fermi level of Au is in the middle of LUMO and 2 2 and carboxylic acid (COOH), respectively . Thus, the HOMO. Thus, we can infer the Fermi level of Au can be tunneling decay with iodine shows the lowest value around the average energy level of LUMO and HOMO, among those anchoring groups with a trend β (thiol) > which are − 4.25 and − 4.35 eV established from β (amine) > β (carboxylic acid) > β (iodine), which TOTOT and TTO TT, respectively. The Fermi level of N N N P may be due to the difference in the alignment of mo- Au − 4.25 and − 4.35 eV are similar to that measured by lecular energy levels to the Fermi level of Au electrode UPS with − 4.2 eV . According to the above, we will [23, 31]. The tunneling decay of 0.5 per –CH can also use the − 4.2 eV as the Fermi level of Au electrode with −1 be converted to 4 nm , which is comparable to the adsorption of molecule. −1 oligophenyls with 3.5–5nm [40, 41]. Assuming the Fermi level of − 4.2 eV for Au with SAM, The β for the metal-molecule-metal junctions can be C6DT and C6DA are the HOMO-dominated electron simply described by the below equation [17, 20, 38], transport, while LUMO-dominated electron transport is proposed for the C6DC and C6DI. Thus, the barrier rﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃ height Φ can be established as 1.98 eV (C6DT), 1.82 eV 2mΦ β α (C6DA), 1.62 eV (C6DC), and 1.59 eV (C6DI) (Table 1). The trend for the barrier height between the molecule and where m is the effective electron mass and is the re- Au is Φ (thiol) > Φ (amine) > Φ (carboxylic C6DT C6DA C6DC duced Planck’s constant. Φ represents the barrier height, acid) > Φ (iodine), which is consistent with the trend C6DI which is decided by the energy gap between the Fermi Table 1 Energy levels of the frontier orbitals of molecules level and the molecular energy levels in the junction. contacting with four Au atoms computed by DFT method Obviously, the β value is proportional to the square Au -C6DT-Au Au -C6DA-Au Au -C6DC-Au Au -C6DI-Au 4 4 4 4 4 4 4 4 root of barrier height. Thus, we may propose that (eV) (eV) (eV) (eV) iodine-terminated alkane molecules have small Φ with E − 1.99 − 1.85 − 2.58 − 2.61 LUMO the Au electrode. E − 6.18 − 6.02 − 6.33 − 6.22 HOMO E - 2.21 2.35 1.62 1.59 Barrier Height of Single Molecular Junctions with LUMO Au Different Anchoring Groups E - 1.98 1.82 2.13 2.02 Au Taking the –(CH ) – as the backbone, we performed the 2 6 HOMO rough calculations (see computational detail in Peng et al. Nanoscale Research Letters (2018) 13:121 Page 5 of 6 of the tunneling decay (β). Thus, the unusual low Received: 10 February 2018 Accepted: 16 April 2018 tunneling decay can be contributed to the small bar- rier height between iodine-terminated alkane mole- References cules and Au. 1. Huang CC, Jevric M, Borges A, Olsen ST, Hamill JM, Zheng JT, Yang Y, Rudnev A, Baghernejad M, Broekmann P et al (2017) Single-molecule detection of dihydroazulene photo-thermal reaction using break junction Conclusions technique. Nat Commun 8:15436 2. Sedghi G, Garcia-Suarez VM, Esdaile LJ, Anderson HL, Lambert CJ, Martin S, In conclusion, we have measured the conductance of Bethell D, Higgins SJ, Elliott M, Bennett N et al (2011) Long-range electron alkane-based molecules with iodine group contacting to tunnelling in oligo-porphyrin molecular wires. Nat Nanotechnol 6:517–523 Au electrodes by STM-BJ at room temperature. A 3. Mativetsky JM, Pace G, Elbing M, Rampi MA, Mayor M, Samori P (2008) Azobenzenes as light-controlled molecular electronic switches in nanoscale tunneling decay β of 0.5 per –CH was found for those N 2 metal-molecule-metal junctions. J Am Chem Soc 130:9192–9193 molecules with Au electrodes, which is much lower than 4. Darwish N, Aragones AC, Darwish T, Ciampi S, Diez-Perez I (2014) Multi- that of alkane-based molecules with other anchoring responsive photo- and chemo-electrical single-molecule switches. Nano Lett 14:7064–7070 groups. This can be caused by the small barrier height 5. Zhang JL, Zhong JQ, Lin JD, Hu WP, Wu K, Xu GQ, ATS W, Chen W (2015) between the iodine-terminated alkane molecule and Au. Towards single molecule switches. Chem Soc Rev 44:2998–3022 The current work shows the important role of the 6. Diez-Perez I, Hihath J, Lee Y, Yu LP, Adamska L, Kozhushner MA, Oleynik II, Tao NJ (2009) Rectification and stability of a single molecular diode with anchoring group in electrical characteristics of single controlled orientation. Nat Chem 1:635–641 molecular junctions, which can tune the tunneling decay 7. Capozzi B, Xia J, Adak O, Dell EJ, Liu Z-F, Taylor JC, Neaton JB, Campos LM, of molecular junction and guide the manufacturing Venkataraman L (2015) Single-molecule diodes with high rectification ratios through environmental control. Nat Nanotechnol 10:522–527 molecular wire. 8. Xu BQ, Xiao XY, Yang XM, Zang L, Tao NJ (2005) Large gate modulation in the current of a room temperature single molecule transistor. J Am Chem Soc 127:2386–2387 Additional file 9. Osorio HM, Catarelli S, Cea P, Gluyas JBG, Hartl F, Higgins SJ, Leary E, Low PJ, Martín S, Nichols RJ et al (2015) Electrochemical single-molecule Additional file 1: Two-dimensional conductance histograms of transistors with optimized gate coupling. J Am Chem Soc 137:14319–14328 molecular junctions and computational details. (DOCX 173 kb) 10. Perrin ML, Burzuri E, van der Zant HSJ (2015) Single-molecule transistors. Chem Soc Rev 44:902–919 11. Seth C, Kaliginedi V, Suravarapu S, Reber D, Hong WJ, Wandlowski T, Lafolet F, Broekmann P, Royal G, Venkatramani R (2017) Conductance in a bis-terpyridine Abbreviations based single molecular breadboard circuit. Chem Sci 8:1576–1591 HOMO: Highest occupied molecular orbital; LUMO: Lowest unoccupied 12. Su TA, Neupane M, Steigerwald ML, Venkataraman L, Nuckolls C (2016) molecular orbital; SAMs: Self-assembled monolayers; STM-BJ: Scanning Chemical principles of single-molecule electronics. Nat Rev Mater 1:16002 tunneling microscopy break junction; UPS: Ultraviolet photoelectron 13. Yang Y, Liu JY, Feng S, Wen HM, Tian JH, Zheng JT, Schollhorn B, Amatore spectroscopy 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 Funding 14. Ie Y, Tanaka K, Tashiro A, Lee SK, Testai HR, Yamada R, Tada H, Aso Y (2015) We gratefully thank the financial support by the National Natural Science Thiophene-based tripodal anchor units for hole transport in single-molecule Foundation of China (nos. 21573198, 21273204 and 21406137), Zhejiang junctions with gold electrodes. J Phys Chem Lett 6:3754–3759 Provincial Natural Science Foundation of China (no. LR15B030002), the 15. Xin N, Jia C, Wang J, Wang S, Li M, Gong Y, Zhang G, Zhu D, Guo X (2017) Natural Science Foundation of Shanghai (no. 17ZR1447100), the Program for Thermally activated tunneling transition in a photoswitchable single- Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions molecule electrical junction. J Phys Chem Lett 8:2849–2854 of Higher Learning, and the Key Laboratory of Spectrochemical Analysis & 16. Chen F, Peng LL, Hong ZW, Mao JC, Zheng JF, Shao Y, Niu ZJ, Zhou XS Instrumentation (Xiamen University), Ministry of Education (SCAI1604). (2016) Comparative study on single-molecule junctions of alkane- and benzene-based molecules with carboxylic acid/aldehyde as the anchoring Availability of Data and Materials groups. Nanoscale Res Lett 11:380 The datasets supporting the conclusions of this article are included within 17. Salomon A, Cahen D, Lindsay S, Tomfohr J, Engelkes VB, Frisbie CD (2003) the article and its additional file. Comparison of electronic transport measurements on organic molecules. Adv Mater 15:1881–1890 18. Arroyo CR, Tarkuc S, Frisenda R, Seldenthuis JS, Woerde CHM, Eelkema R, Authors’ Contributions Grozema FC, van der Zant HSJ (2013) Signatures of quantum interference LLP, BH, ZWH, and JFZ carried out the experiments; QZ, YS, and ZJN effects on charge transport through a single benzene ring. Angew Chem contributed to the analyzed the results. HJX performed the calculations. LLP, Int Ed 52:3152–3155 XSZ, and WB conceived and designed the experiments and analyzed the 19. Xiang D, Wang X, Jia C, Lee T, Guo X (2016) Molecular-scale electronics: results and wrote the manuscript. All authors read and approved the final from concept to function. Chem Rev 116:4318–4440 manuscript. 20. Engelkes VB, Beebe JM, Frisbie CD (2004) Length-dependent transport in molecular junctions based on SAMs of alkanethiols and alkanedithiols: effect of metal work function and applied bias on tunneling efficiency and Competing Interests contact resistance. J Am Chem Soc 126:14287–14296 The authors declare that they have no competing interests. 21. 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 Publisher’sNote 22. Capozzi B, Chen Q, Darancet P, Kotiuga M, Buzzeo M, Neaton JB, Nuckolls C, Springer Nature remains neutral with regard to jurisdictional claims in Venkataraman L (2014) Tunable charge transport in single-molecule published maps and institutional affiliations. junctions via electrolytic gating. Nano Lett 14:1400–1404 Peng et al. Nanoscale Research Letters (2018) 13:121 Page 6 of 6 23. Chen F, Li XL, Hihath J, Huang ZF, Tao NJ (2006) Effect of anchoring groups 44. Yuan L, Franco C, Crivillers N, Mas-Torrent M, Cao L, Sangeeth CSS, Rovira C, on single-molecule conductance: comparative study of thiol-, amine-, and Veciana J, Nijhuis CA (2016) Chemical control over the energy-level carboxylic-acid-terminated molecules. J Am Chem Soc 128:15874–15881 alignment in a two-terminal junction. Nat Commun 7:12066 24. Kaliginedi V, Rudnev AV, Moreno-Garcia P, Baghernejad M, Huang C, Hong 45. Low JZ, Capozzi B, Cui J, Wei SJ, Venkataraman L, Campos LM (2017) Tuning W, Wandlowski T (2014) Promising anchoring groups for single-molecule the polarity of charge carriers using electron deficient thiophenes. Chem Sci conductance measurements. Phys Chem Chem Phys 16:23529–23539 8:3254–3259 25. Park YS, Whalley AC, Kamenetska M, Steigerwald ML, Hybertsen MS, Nuckolls C, Venkataraman L (2007) Contact chemistry and single-molecule conductance: a comparison of phosphines, methyl sulfides, and amines. J Am Chem Soc 129:15768–15769 26. Xiang LM, Hines T, Palma JL, Lu XF, Mujica V, Ratner MA, Zhou G, Tao NJ (2016) Non-exponential length dependence of conductance in iodide terminated oligothiophene single-molecule tunneling junctions. J Am Chem Soc 138:679–687 27. Komoto Y, Fujii S, Hara K, Kiguchi M (2013) Single molecular bridging of Au nanogap using aryl halide molecules. J Phys Chem C 117:24277–24282 28. Zhou XS, Liu L, Fortgang P, Lefevre A-S, Serra-Muns A, Raouafi N, Amatore C, Mao BW, Maisonhaute E, Schollhorn B (2011) Do molecular conductances correlate with electrochemical rate constants? Experimental insights. J Am Chem Soc 133:7509–7516 29. Chen L, Wang YH, He B, Nie H, Hu R, Huang F, Qin A, Zhou XS, Zhao Z, Tang BZ (2015) Multichannel conductance of folded single-molecule wires aided by through-space conjugation. Angew Chem Int Ed 54:4231–4235 30. Mao JC, Peng LL, Li WQ, Chen F, Wang HG, Shao Y, Zhou XS, Zhao XQ, Xie H, Niu ZJ (2017) Influence of molecular structure on contact interaction between thiophene anchoring group and Au electrode. J Phys Chem C 121:1472–1476 31. Venkataraman L, Klare JE, Tam IW, Nuckolls C, Hybertsen MS, Steigerwald ML (2006) Single-molecule circuits with well-defined molecular conductance. Nano Lett 6:458–462 32. 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 33. Huang C, Chen S, Ornso KB, Reber D, Baghernejad M, Fu Y, Wandlowski T, Decurtins S, Hong W, Thygesen KS, Liu S-X (2015) Controlling electrical conductance through a pi-conjugated cruciform molecule by selective anchoring to gold electrodes. Angew Chem Int Ed 54:14304–14307 34. 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. JAmChemSoc 134:5262–5275 35. Yanson AI, Bollinger GR, van den Brom HE, Agrait N, van Ruitenbeek JM (1998) Formation and manipulation of a metallic wire of single gold atoms. Nat 395:783–785 36. Eder G, Smith EF, Cebula I, Heckl WM, Beton PH, Lackinger M (2013) Solution preparation of two-dimensional covalently linked networks by polymerization of 1,3,5-tri (4-iodophenyl) benzene on Au (111). ACS Nano 7:3014–3021 37. Cheng ZL, Skouta R, Vazquez H, Widawsky JR, SchneebeliS CW, Hybertsen MS, Breslow R, Venkataraman L (2011) In situ formation of highly conducting covalent Au-C contacts for single-molecule junctions. Nat Nanotechnol 6:353–357 38. 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 39. 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 40. Wold DJ, Haag R, Rampi MA, Frisbie CD (2002) Distance dependence of electron tunneling through self-assembled monolayers measured by conducting probe atomic force microscopy: unsaturated versus saturated molecular junctions. J Phys Chem B 106:2813–2816 41. Kim T, Vázquez H, Hybertsen MS, Venkataraman L (2013) Conductance of molecular junctions formed with silver electrodes. Nano Lett 13:3358–3364 42. Michaelson HB (1977) The work function of the elements and its periodicity. J Appl Phys 48:4729–4733 43. Kim B, Choi SH, Zhu XY, Frisbie CD (2011) Molecular tunnel junctions based on π-conjugated oligoacene thiols and dithiols between Ag, Au, and Pt contacts: effect of surface linking group and metal work function. J Am Chem Soc 133:19864–19877
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Published: Apr 24, 2018
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