Imine linked chemosensors coupled with ZnO: Fluorescent and chromogenic detection of Al3+

doi:10.1016/j.matlet.2012.06.066

Materials Letters

Volume 84, 1 October 2012, Pages 104-106

https://doi.org/10.1016/j.matlet.2012.06.066 Get rights and content

Abstract

The surface of ZnO nanoparticles is decorated with dipodal receptors having imine linkages. The cation recognition properties of pure dipodal receptors and same receptors coated on ZnO have been compared. The dipodal receptors which were previously non-selective become highly selectivity for Al³⁺ after capping on the surface of ZnO nanoparticles. The ZnO nanoparticles were prepared by the sol–gel method and characterized through powder X-ray diffraction. Two spectroscopic techniques have been used to study the cation recognition behavior of receptors. The ZnO coated assemblies authenticate their use as sensitive sensors for Al³⁺ in a semi-aqueous medium by showing some remarkable changes in its profile.

Graphical abstract

Highlights

► The decoration of dipoadal receptors on ZnO nanoparticles. ► The morphology is changed after complexation. ► The sensor 3 showed ratiometric response for Al³⁺. ► A PET mechanism is responsible for Al³⁺ detection on fluorescence.

Introduction

For the identification and quantification of important physiological and environmental analytes, the development of chemosensors is of considerable importance [1], [2], [3], [4], [5], [6], [7]. These chemosensors when undergo complexation with cation, an informative signal in the form of changes in specific photophysical properties is detected. These changes have specific importance in analyte sensing systems particularly in environmental and biological applications [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19]. For the effective operational usage of these chemosensors, their sensitivity and selectivity should be high. A variety of chemosensors are reported in literature, including several inorganic–organic hybrids fabricated with organic receptors and metal oxides like ZnO [20]. ZnO itself shows some significant properties, which makes it an excellent candidate for hybrid solar cells. Due to ferromagnetic properties of nanostructured ZnO, it can be used in spintronics. Whereas in case of doped ZnO, the ferromagnetic properties depend upon grain boundaries [21], [22]. A grain size is also the cause on which the absorption ability of these nanostructures depends [23]. ZnO is very less toxic and a very wide range of nanostructures can be synthesized from it. The efficient excitonic emission at room temperature can be ensured due to high exciton binding energy in ZnO crystal. Where as in disordered nanoparticles and thin films, ultraviolet luminescence at room temperature has been observed. ZnO can be made extremely conductive by doping and is transparent to visible light. Exhibition of narrow emission bands and high stability has been shown by these colloidal nanocrystals against oxidants and photo-oxidant [24]. To follow the same line of research interest, present study is designed for surface decoration of ZnO with some imine linked receptors [25], [26], [27], [28]. The recognition properties of imine linked receptor and receptor decorated on ZnO is then evaluated.

Section snippets

Result and discussion

The sensors 1 and 2 were synthesized using a condensation reaction between diethylene triamine and respective aldehydes. The formation of imine linkage was characterized through a signal at 8.47 and 8.68 ppm in ¹H NMR spectra of 1 and 2 respectively. The same was further confirmed through a band in-between 1632 and 1699 cm⁻¹ in IR spectra of 1 and 2 (Fig. S2). Receptors 3 and 4 were synthesized via in-situ synthesis of ZnO in the presence of 1 and 2 respectively [24], [25]. The decoration of 1

Conclusion

The receptor 1 and 2 showed high selectivity for Al³⁺ after capping on the surface of ZnO nanoparticles. These receptors detect Al³⁺ by using two different spectroscopic techniques. The sensor 3 showed ratiometric determination on the UV–visible spectrophotometer. However, sensor 4 detects Al³⁺ on Fluorescence through PET mechanism.

Acknowledgments

Authors are thankful to SAIF Chandigarh for NMR. This work was supported by CSIR Research Project [01(2417)/10/EMR-11] and HS is thankful to IIT Ropar for fellowship.

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Imine linked chemosensors coupled with ZnO: Fluorescent and chromogenic detection of Al3+

Abstract

Graphical abstract

Highlights

Introduction

Section snippets

Result and discussion

Conclusion

Acknowledgments

Sensors Actuators B: Chem

Sensors Actuators B: Chem

Sensors Actuators B: Chem

Tetrahedron Lett

Mater Lett

J Eur Ceram Soc

Mater Lett

Tetrahedron

Inorg Chem Commun

Tetrahedron Lett

Chem Soc Rev

Appl Mater Interfaces

J Am Chem Soc

Chem Rev

Imine linked chemosensors coupled with ZnO: Fluorescent and chromogenic detection of Al³⁺