In this article, we report on the characterization of various molecular junctions＇ current-voltage characteristics （Ⅰ-Ⅴ curves） evolution under mechanical modulations, by employing a novel electrochemically assis...In this article, we report on the characterization of various molecular junctions＇ current-voltage characteristics （Ⅰ-Ⅴ curves） evolution under mechanical modulations, by employing a novel electrochemically assisted-mechanically controllable break junction （EC-MCBJ） method. For 1,4-benzenedithiol, the Ⅰ-Ⅴ curves measured at constant electrode pair separation show excellent reproducibility, indicating the feasibility of our EC-MCBJ method for fabricating molecular junctions. For ferrocene-bisvinylphenylmethyl dithiol （Fc-VPM）, an anomalous type of Ⅰ-Ⅴ curve was observed by the particular control over the stepping motor. This phenomenon is rationalized assuming a model of atomic contact evolution with the presence of molecular junctions. To test this hypothesized model, a molecule with a longer length, 1,3-butadiyne-linked dinuclear ruthenium（H） complex （Ru-1）, was implemented, and the Ⅰ-Ⅴ curve evolution was investigated under similar circumstances. Compared with Fc-VPM, the observed Ⅰ-Ⅴ curves show close analogy and minor differences, and both of them fit the hypothesized model well.展开更多
Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have b...Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.展开更多
基金This work was supported by the National Basic Research Program of China （Nos. 2011YQ030124, 2014CB845603, and 2015CB932301）, National Natural Science Foundation of China （Nos. 91427304, 21321062, 21303114, 21403181, and 21503179）, Natural Science Foundation of Fujian Province （No. 2012J05034）, and by CNRS UMR 8640 PASTEUR and LIA CNRS NanoBioCatEchem.
文摘In this article, we report on the characterization of various molecular junctions＇ current-voltage characteristics （Ⅰ-Ⅴ curves） evolution under mechanical modulations, by employing a novel electrochemically assisted-mechanically controllable break junction （EC-MCBJ） method. For 1,4-benzenedithiol, the Ⅰ-Ⅴ curves measured at constant electrode pair separation show excellent reproducibility, indicating the feasibility of our EC-MCBJ method for fabricating molecular junctions. For ferrocene-bisvinylphenylmethyl dithiol （Fc-VPM）, an anomalous type of Ⅰ-Ⅴ curve was observed by the particular control over the stepping motor. This phenomenon is rationalized assuming a model of atomic contact evolution with the presence of molecular junctions. To test this hypothesized model, a molecule with a longer length, 1,3-butadiyne-linked dinuclear ruthenium（H） complex （Ru-1）, was implemented, and the Ⅰ-Ⅴ curve evolution was investigated under similar circumstances. Compared with Fc-VPM, the observed Ⅰ-Ⅴ curves show close analogy and minor differences, and both of them fit the hypothesized model well.
基金supported by the National Natural Science Foundation of China(grant nos.T2222002,21973079,22032004,92161118,12174324,21991130,and 21905238)the Ministry of Science and Technology of the People’s Republic of China(grant no.2021YFA1201502)the Natural Science Foundation of Fujian Province(grant no.2021J06008).
文摘Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.
