Related Experiment Video
Updated: Nov 30, 2025
09:48
Investigating Single Molecule Adhesion by Atomic Force Spectroscopy
Published on: February 27, 2015
10.7K
Single-Molecule Sensing of Interfacial Acid-Base Chemistry
Cai-Ping Tao1, Chen-Chen Jiang1, Ya-Hao Wang1
1Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
The Journal of Physical Chemistry Letters
|November 12, 2020
Summary
This study uses scanning tunneling microscopy break junction (STM-BJ) to probe single-molecule acid-base chemistry at solid-liquid interfaces. Researchers developed a prototype single-molecule pH sensor based on carboxylic acid molecules on a gold surface.
Area of Science:
- Surface Chemistry
- Nanotechnology
- Analytical Chemistry
Background:
- Bronsted acid-base interactions are fundamental in chemistry.
- Probing these interactions at the solid-liquid interface at the single-molecule level is challenging.
Purpose of the Study:
- Investigate single-molecule acid-base chemistry of carboxylic acids on a gold surface.
- Develop a prototype single-molecule pH sensor.
Main Methods:
- Scanning tunneling microscopy break junction (STM-BJ) technique.
- Utilized a Au (111) model surface with carboxylic acid-based molecules.
- Performed single-molecule measurements under varying environmental conditions.
Main Results:
- Junction formation probability correlates with the deprotonated carboxylate (-COO-) form population.
- Conductance peak intensity variation with pH follows a Henderson-Hasselbalch type equation.
- Established a linear relationship between -COOH dissociation degree and environmental pH.
Conclusions:
- Demonstrated a feasible method for single-molecule pH sensing.
- The study provides a pathway for designing single-molecule chemical and biosensors.
- Highlights the potential for single-molecule scale detection applications.
