Cucurbituril mediated single molecule detection and identification via recognition tunneling

Xiao, Bohuai; Liang, Feng; Liu, Simin; Im, JongOne; Li, Yunchuan; Liu, Jing; Zhang, Bintian; Zhou, Jianghao; He, Jin; Chang, Shuai

doi:10.1088/1361-6528/aacb63

Cited by 28 publications

(38 citation statements)

References 49 publications

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“…However, it is worth noting that compared with CB[7], the Mel@CB[7] complex showed a smaller conductance at the same pH. Guest molecule in the cavity of CB[7] had an impact on electronic transport process, which is consistent with the previous report (Xiao et al, 2018 ). Furthermore, the mean lifetime of the switching events for Mel@CB[7] was between 6 and 7 ms, which was smaller than that for CB[7].…”

Section: Single Molecule Conductance Measurements Of Mel@cb[7]supporting

confidence: 90%

“…Where I is current, I 0 is the tunneling current before the observation of the current jump, V is the applied bias. In this report, the baseline current I 0 is 20 nA, and the bias V is 0.1 V, which follows the previous report (Xiao et al, 2018 ). The histograms of conductance G vs. G 0 were plotted in semi-log scale, where G 0 is quantum of conductance 77.4 μS, as shown in Figure 2A (in PB) and C (in TCB).…”

Section: Single Molecule Conductance Measurements Of Cb[7]supporting

confidence: 86%

“…The time-dependent STM image of CB[7] functionalized gold substrate was shown in Figure S1A. The appearance of pits in the STM image suggested that CB [7] can interact with the gold substrate to relocate the surface gold atoms (Xiao et al, 2018), which indicated the successful modification of CB [7]. This was further proven by the decrease of contact angle after modifying CB[7] ( Figure S1B).…”

Section: Resultsmentioning

confidence: 93%

“…For each sample, 2~3 gold probes were used to collect hundreds of experimental runs over different sample positions. The PZT servo response time was about 30 ms, as described previously (Xiao et al, 2018 ). Current spikes were analyzed by home-built Labview programs.…”

Section: Methodsmentioning

confidence: 99%

“…The single molecule conductance of CB[7] can be determined by transient current changes (Haiss et al, 2004 ; Xiao et al, 2018 ).…”

Section: Single Molecule Conductance Measurements Of Cb[7]mentioning

confidence: 99%

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pH-Mediated Single Molecule Conductance of Cucurbit[7]uril

Liang

2020

Front. Chem.

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Recognition tunneling technique owns the capability for investigating and characterizing molecules at single molecule level. Here, we investigated the conductance value of cucurbit[7]uril (CB[7]) and melphalan@CB[7] (Mel@CB[7]) complex molecular junctions by using recognition tunneling technique. The conductances of CB[7] and Mel@CB[7] with different pH values were studied in aqueous media as well as organic solvent. Both pH value and guest molecule have an impact on the conductance of CB[7] molecular junction. The conductances of CB[7] and Mel@CB[7] both showed slightly difference on the conductance under different measurement systems. This work extends the molecular conductance measurement to aqueous media and provides new insights of pH-responsive host-guest system for single molecule detection through electrical measurements.

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Section: Single Molecule Conductance Measurements Of Mel@cb[7]supporting

confidence: 90%

Section: Single Molecule Conductance Measurements Of Cb[7]supporting

confidence: 86%

Section: Resultsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

“…The single molecule conductance of CB[7] can be determined by transient current changes (Haiss et al, 2004 ; Xiao et al, 2018 ).…”

Section: Single Molecule Conductance Measurements Of Cb[7]mentioning

confidence: 99%

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pH-Mediated Single Molecule Conductance of Cucurbit[7]uril

Liang

2020

Front. Chem.

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Photoconductance Induced by Excited‐State Intramolecular Proton Transfer (ESIPT) in Single‐Molecule Junctions

Wang,

Chen,

Lei

et al. 2024

Advanced Materials

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Excited‐state intramolecular Proton Transfer (ESIPT) molecules have been drawing considerable attention due to their unique photophysical properties and potential applications in optoelectronic devices. Although ground and excited‐state tautomerism in various proton transfer systems associated with ESIPT has been extensively studied both experimentally and theoretically, the charge‐transport characteristics of ESIPT molecules at the single‐molecule level has been little investigated. In this work, scanning tunneling microscope‐based fixed junction technique (STM‐FJ) is employed with theoretical calculations to explore the electronic properties of SMe‐PhOH (with ESIPT properties), together with its photoconductance induced by ESIPT photocycle processes under continuous light illumination (254/275/295/310 nm). The conductance variation of SMe‐PhOH with different UV wavelengths exhibits a continuous photoconductance distribution, which is highly consistent with the results of its UV–vis absorption spectrum. Theoretical calculations indicate that the interaction between localized HOMO and delocalized LUMO of SMe‐PhOH K*‐state gives rise to Fano resonance, thereby leading to enhanced conductance compared with its E‐state. It reveals the microscopic mechanism of ESIPT process at the nanoscale and provides a constructive perspective for optimizing the photoresponsive properties of ESIPT‐type molecules, as well as designing high‐performance single‐molecule devices.

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Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

Xiao

Sun

et al. 2022

Angewandte Chemie

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We introduce a versatile recognition tunneling technique using doubly cucurbit[7]uril‐functionalized electrodes to form supramolecular junctions that capture analytes dynamically by host–guest complexation. This results in characteristic changes in their single‐molecule conductance. For structurally related drug molecules (camptothecin, sanguinarine, chelerythrine, and berberine) and mixtures thereof, we observed distinct current switching signals related to their intrinsic conductance properties as well as pH‐dependent effects which can be traced back to their different states (protonated versus neutral). The conductance variation of a single molecule with pH shows a sigmoidal distribution, allowing us to extract a pKa value for reversible protonation, which is consistent with the reported macroscopic results. The new electronic method allows the characterization of unmodified drug molecules and showcases the transfer of dynamic supramolecular chemistry principles to single molecules.

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Cucurbituril mediated single molecule detection and identification via recognition tunneling

Cited by 28 publications

References 49 publications

pH-Mediated Single Molecule Conductance of Cucurbit[7]uril

pH-Mediated Single Molecule Conductance of Cucurbit[7]uril

Photoconductance Induced by Excited‐State Intramolecular Proton Transfer (ESIPT) in Single‐Molecule Junctions

Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

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