Ester formation at the liquid-solid interface.

Nguyen T N Ha,Lars Smykalla,Tobias Rüffer,Nguyen D C Yen,Maik Schlesinger,Roy Buschbeck,Heinrich Lang,Michael Mehring,Michael Hietschold,Thiruvancheril G Gopakumar,Carola Mende

doi:10.3762/bjnano.8.213

Abstract

A chemical reaction (esterification) within a molecular monolayer at the liquid–solid interface without any catalyst was studied using ambient scanning tunneling microscopy. The monolayer consisted of a regular array of two species, an organic acid (trimesic acid) and an alcohol (undecan-1-ol or decan-1-ol), coadsorbed out of a solution of the acid within the alcohol at the interface of highly oriented pyrolytic graphite (HOPG) (0001) substrate. The monoester was observed promptly after reaching a threshold either related to the increased packing density of the adsorbate layer (which can be controlled by the concentration of the trimesic acid within the alcoholic solution via sonication or extended stirring) or by reaching a threshold with regards to the deposition temperature. Evidence that esterification takes place directly at the liquid–solid interface was strongly supported.

Highlights

On-surface reactions are a widespread class of chemical reactions taking place on a surface or at an interface involving active participation of two-dimensional molecular entities
This is consistent with the reported linear pattern (LP) of alcohol and Trimesic acid (TMA) coadsorbed on the highly oriented pyrolytic graphite (HOPG) (0001) surface [26,27]
TMA interacts with undecanol via noncovalent hydrogen bonding and forms the observed LP

Summary

Introduction

On-surface reactions are a widespread class of chemical reactions taking place on a surface or at an interface involving active participation of two-dimensional molecular entities. This participation is usually beyond the role of just being a solid support for the reactants. Using scanning tunneling microscopy (STM) it is possible to actively study the elementary processes of on-surface reactions. Have been explored on surfaces [1,2,3,4,5,6,7,8,9,10,11,12,13,14].

Results

Discussion

Conclusion