Self-assembly film of azobenzene and layered double hydroxide and its application as a light-controlled reversible sensor for the detection of Be2+

This paper reports the fabrication of optical chemosensors based on the self-assembly of Azobenzene (2-(3,6-disulfo-8-hydroxynaphthylazo)-1,8-dihydroxynaphthalene-3,6-disulfonate) and layered double hydroxides (LDHs) nanosheet, which demonstrates sensory property for Be2+ and reversible response to UV and visible light. The fluorescence intensity of the UTF is linear proportional to Be2+ concentration in the range 0.1-1.2 p,M. The absolute detection limit is 3 nM (S/N = 3). Moreover, the UTF shows reversibly optical behavior through alternate irradiating by UV and visible light. Combining sensory and light response property, the light-controlled reversible sensor for detection of Be2+ was realized. The chemosensor displays a good repeatability (RSD less than 1.1% in 5 consecutive measurements). Study on the mechanism shows the light-controlled reversible behavior leads to reversible change of elements, structure and morphology of the UTF confirmed by XPS, Raman, XRD, and AFM. Therefore, we provided a high efficient, clean and environmental-friendly method to achieve reversibility of optical chemosensor by employing light as controlled condition, which open a new avenue to design the advanced optical sensors and switches. (C) 2015 Elsevier B.V. All rights reserved.