Interaction of VOCs with pyrene tetratopic ligands layered on ZnO nanorods under visible light

In this work, the relationship between photosensitivity and chemical sensitivity of zinc oxide (ZnO) nanorods coated with pyrene based tetratopic ligands (PTL) is investigated under visible light. The electrical resistance of ZnO-PTL is affected by adsorption of different volatile organic compounds (VOCs) such as ethanol, n-hexane, trimethylamine, and triethylamine. The illumination strongly affects the response to the VOCs. To elucidate the interaction mechanism between PTL and VOCs, the experimental studies have been complemented by first principles calculations. Both experimental and computational results have shown that the amines are bound to PTL with higher affinity followed by ethanol (alcohol) and n-hexane (alkane). Our results have proved that the COOH functional group at the peripheral site of PTL is not only used for anchoring the molecule onto the ZnO, but it is also the main adsorption site for the VOCs, in particular for amines. In practice, the photo-optical properties of pyrene molecules are complemented by the high affinity of COOH group for amines in order to achieve a photo-activated sensor. The complementary use of optical dyes and chemical ligands can provide an innovative methodology for chemical sensors design. (C) 2016 Elsevier B.V. All rights reserved.