State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China.
Anal Chem. 2019 Nov 19;91(22):14508-14513. doi: 10.1021/acs.analchem.9b03332. Epub 2019 Oct 28.
Water infrared probe has been employed for in situ monitoring of the detailed self-assembly processes of four thiol molecules with different end groups (-CH, -NH, -COOH, and -OH) on gold nanoparticles (Au NPs) film in aqueous solution. Based on the change of water IR signal, the significant influence of end group properties on the kinetics and thermodynamics of thiols self-assembly can be estimated. It is found that the assembly kinetics of thiols decreases with the increase of the hydrophobicity of the end groups. In addition, the charges carried by the end groups (-COOH and -NH terminated thiols) will also slow down the self-assembly kinetics owing to the electrostatic repulsions. However, the isothermal adsorption is only affected by the wettability of the end groups of thiols. The higher hydrophilicity of the end groups results in larger equilibrium constant of the self-assembly process. Results show that water infrared probe offers an additional approach to the monitoring of thiols self-assembly processes with higher sensitivity and more detailed information as compared to traditional molecule fingerprints.
水红外探针已被用于原位监测四种具有不同末端基团（-CH、-NH、-COOH 和 -OH）的巯基分子在金纳米粒子（Au NPs）薄膜上在水溶液中的详细自组装过程。基于水 IR 信号的变化，可以估计末端基团性质对硫醇自组装动力学和热力学的显著影响。结果发现，随着末端基团疏水性的增加，硫醇的组装动力学会减慢。此外，由于静电排斥，末端基团（-COOH 和 -NH 端基的硫醇）所携带的电荷也会使自组装动力学减慢。然而，等温吸附仅受硫醇末端基团润湿性的影响。末端基团的亲水性越高，自组装过程的平衡常数就越大。结果表明，与传统的分子指纹图谱相比，水红外探针提供了一种更灵敏、更详细的监测硫醇自组装过程的方法。
