Smart supramolecular sensing with cucurbit[n]urils: probing hydrogen bonding with SERS.

Bart De Nijs,Cloudy Carnegie,William M Deacon,Oren A Scherman,Marlous Kamp,Istvan Szabó,Wenting Wang,Rohit Chikkaraddy,Edina Rosta,Guanglu Wu,Steven J Barrow,Jeremy J Baumberg,Felix Benz

doi:10.1039/c7fd00147a

Bart De Nijs, Cloudy Carnegie + Show 11 more

Open Access

https://doi.org/10.1039/c7fd00147a

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Abstract

Rigid gap nano-aggregates of Au nanoparticles formed using cucurbit[n]uril (CB[n]) molecules are used to investigate the competitive binding of ethanol and methanol in an aqueous environment. We show it is possible to detect as little as 0.1% methanol in water and a ten times higher affinity to methanol over ethanol, making this a useful technology for quality control in alcohol production. We demonstrate strong interaction effects in the SERS peaks, which we demonstrate are likely from the hydrogen bonding of water complexes in the vicinity of the CB[n]s.

Highlights

Surface-Enhanced Raman Scattering (SERS) has attracted wide-spread interest on account of its potential for sensing down to the single molecule level.1–8 This has led to a wealth of research on detecting trace amounts of pollutants,9 poisons10 and explosives,11,12 achieved by plasmonic constructs such as core–shell nanoparticles,13 nanostars,14–18 nanoparticle aggregates,19,20 nanowire junctions21–24 and plasmonic tips25–27 (Tip-Enhanced Raman Scattering, TERS)
We demonstrate strong interaction effects in the SERS peaks, which we demonstrate are likely from the hydrogen bonding of water complexes in the vicinity of the CB[n]s
Upon adding increasing amounts of MeOH (0–1.9 v/v%) to the CB[5]–AuNP constructs in water, clear spectral changes emerge with distinct peaks at 1564 cmÀ1 and 1604 cmÀ1 (Fig. 1b and c: green)

Summary

Introduction

Surface-Enhanced Raman Scattering (SERS) has attracted wide-spread interest on account of its potential for sensing down to the single molecule level.1–8 This has led to a wealth of research on detecting trace amounts of pollutants,9 poisons10 and explosives,11,12 achieved by plasmonic constructs such as core–shell nanoparticles,13 nanostars,14–18 nanoparticle aggregates,19,20 nanowire junctions21–24 and plasmonic tips25–27 (Tip-Enhanced Raman Scattering, TERS). In addition to being useful in view of public health and safety, our results show that the hydrogen bonding between MeOH and water and EtOH and water can be directly probed using plasmonic CB [n]–AuNP constructs, opening up avenues to studying the molecular dynamics of solvent molecule mixtures using SERS. Upon adding increasing amounts of MeOH (0–1.9 v/v%) to the CB[5]–AuNP constructs in water, clear spectral changes emerge with distinct peaks at 1564 cmÀ1 and 1604 cmÀ1 (Fig. 1b and c: green).

Results

Conclusion