Luminescent and Chiroptical Properties of 1 : 1 Eu (III) : Tetracycline Species Probed by Circularly Polarized Luminescence

Publication Date

December 2019

Document Type

Article

Publication Title

ChemPlusChem

Volume

84

Issue

12

DOI

10.1002/cplu.201900627

First Page

1796

Last Page

1804

Abstract

This study investigates the significantly different luminescent and chiroptical properties of tetracycline (TC) when coordinated to Eu(III). The approach involves understanding the 1) speciation of TC and 2) conformation and species formed between Eu(III) and TC in a ratio of 1 : 1 in a dimethylformamide (DMF) solution and as a function of the pH value. By identifying the conformational changes of the various 1 : 1 Eu(III) : TC species, the results from this study explain information on the local microenvironment about the Eu(III) metal center. In particular, 5D0←7F0 Eu(III) laser excitation spectroscopy was employed to distinguish the different types of species found in solution in order to understand the interaction between Eu(III) and TC. On the other hand, circularly polarized luminescence (CPL) spectroscopy was used to understand the structural changes within the 1 : 1 Eu(III) : TC complex that could be related to the chirality of the Eu(III)‐containing species. The CPL spectrum serves as a “fingerprint” to indicate the conformational changes within the 1 : 1 Eu(III) : TC complex as a result of the chiroptical signal arising from the various Eu(III) : TC species.

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