Issue 48, 2019

Amplified vibrational circular dichroism as a manifestation of the interaction between a water soluble gold nanocluster and cobalt salt

Abstract

Vibrational circular dichroism (VCD) is a powerful tool for the structure determination of dissolved molecules. However, the application of VCD to nanostructures is limited up to now due to the weakness of the effect and hence the low signal intensities. Here we show that the addition of a small amount of cobalt(II) drastically enhances the VCD signals of a thiolate-protected gold cluster Au25(Capt)18 (Capt = captopril) in aqueous solution. An increase of VCD signal intensity of at least one order of magnitude is observed. The enhancement depends on the amount of CoCl2 added but almost an order of magnitude enhancement is already observed at a cluster : CoCl2 ratio of 1 : 1. In contrast, circular dichroism (CD) and infrared spectra hardly change. The increase in VCD intensity goes along with a qualitative change of the spectrum and the enhancement increases with time reaching a stable state only after several hours. The enhancement is due to an interaction between the cobalt(II) and the cluster, which also leads to quenching of its fluorescence. The behaviour is completely different for free captopril, where the addition of cobalt(II) salt does not affect the VCD spectrum.

Graphical abstract: Amplified vibrational circular dichroism as a manifestation of the interaction between a water soluble gold nanocluster and cobalt salt

Supplementary files

Article information

Article type
Paper
Submitted
31 Aug 2019
Accepted
09 Nov 2019
First published
11 Nov 2019
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2019,11, 23226-23233

Amplified vibrational circular dichroism as a manifestation of the interaction between a water soluble gold nanocluster and cobalt salt

S. Roy Bhattacharya and T. Bürgi, Nanoscale, 2019, 11, 23226 DOI: 10.1039/C9NR07534H

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