Sensing of Metal Ions by Hybrid Systems of a Chiral Schiff Base Zn(II) Complex and Spiropyran

Takashi Onodera,Asami Wada,Masahiko Aonuma,Satomi Morito,Takashiro Akitsu

doi:10.6000/1929-5030.2013.02.02.3

Takashi Onodera, Asami Wada + Show 3 more

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https://doi.org/10.6000/1929-5030.2013.02.02.3

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Abstract

We have constructed three (hybrid) systems for quantitative fluorescence sensing of metal ions by using chiral Schiff base Zn(II) complexes. System 1 is a hybrid system composed of a trans-type chiral Schiff base Zn(II) complex and merocyanine (Mc), which is open-form of spiropyran (Sp) after photoisomerization. Depending on intermolecular interactions and quenching, increase (Zn2+) or decrease (Cu2+ and Gd3+) of fluorescence intensity of Zn(II) complex could be observed as functions of concentration of metal ions. System 2 is a sole component of a salen-type chiral Schiff base Zn(II) complex which can coordinate metal ions. After coordination of Zn2+, Cu2+, and Gd3+ ions, decreasing of fluorescence intensity could be found for all the cases for system 2 under the same condition to system 1. System 3 is a hybrid system being consisted of a salen-type chiral Schiff base Zn(II) complex and Mc. Decrease or increase of fluorescence intensity is in agreement with intermolecular interactions, namely affinity for the Zn(II) complex is Zn2+ > Cu2+ > Gd3+, whereas it is reverse order for Mc. The quantitative spectroscopic nature (detected as absorption, CD, and fluorescence) of these systems is predominantly attributed to both organic ligands and Zn(II) center in a probe complex

Highlights

We make use of finding and collection of metal ions in environment and human body, of which importance is increasing year by year [1,2,3,4,5]
Unclear behavior of ions concentration dependence of intensity may be attributed to incomplete association of metal ions
In the case of Zn2+ ion, quantitative spectral changes could be observed for Circular Dichroism (CD) bands at 260, 280, and 410 nm and little spectral changes could be observed for UV-vis bands at 530 nm in contrast to Cu2+ or Gd3+ ion

Summary

Introduction

We make use of finding and collection of metal ions in environment and human body, of which importance is increasing year by year [1,2,3,4,5]. For this reason specific detection of metal ions in complicate systems composed of many components is needed. Many fluorescent sensors for Zn(II) ion used in solutions have been reported so far [9,10,11,12,13,14], and one of typical recent examples exhibit a strong fluorescence response after coordination Zn(II) ion to non-fluorescent organic ligand [15]. In order to realize such requirement, we will examine multi-functional compounds or hybrid functional systems composed of both fluorescent part of Zn(II) ion and external controlling parts of several mechanisms

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Conclusion