Issue 45, 2017

Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors

Abstract

The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish self-consistent H-bond acceptor parameters (β) for benzoate, azide, chloride, thiocyanate anions, a series of phosphine oxides, phosphate ester, sulfoxide and a tertiary amide. The results demonstrate both the transferability of H-bond parameters between different solvents and the utility of the naphthol-based dual molecular recognition probe to exploit orthogonal spectroscopic techniques to determine the HBA properties of neutral and charged solutes. The benzoate anion is the strongest HBA studied with a β parameter of 15.4, and the neutral tertiary amide is the weakest H-bond acceptor investigated with a β parameter of 8.5. The H-bond acceptor strength of the azide anion is higher than that of chloride (12.8 and 12.2 respectively), and the thiocyanate anion has a β value of 10.8 and thus is a significantly weaker H-bond acceptor than both the azide and chloride anions.

Graphical abstract: Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors

Supplementary files

Article information

Article type
Paper
Submitted
22 aug 2017
Accepted
05 okt 2017
First published
06 nov 2017
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2017,15, 9603-9610

Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors

S. J. Pike and C. A. Hunter, Org. Biomol. Chem., 2017, 15, 9603 DOI: 10.1039/C7OB02092A

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