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Spiropyran-based reversible, light-modulated sensing with reduced photofatigue

Radu, Aleksandar and Byrne, Robert and Alhashimy, Nameer and Fussaro, Massimo and Scarmagnani, Silvia and Diamond, Dermot (2009) Spiropyran-based reversible, light-modulated sensing with reduced photofatigue. Journal of Photochemistry and Photobiology A: Chemistry, 206 (2-3). pp. 109-115. ISSN 1010-6030

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Abstract

Switchable materials have tremendous potential for application in sensor development that could be applied to many fields. We are focusing on emerging area of wireless sensor networks due to the potential impact of this concept in society. Spiropyran-based sensors are probably the most studied type of photoswitchable sensing devices. They suffer from many issues but photofatigue, insufficient selectivity and lack of sensitivity are probably the most important characteristics that hinder their wider application. Here, we are address these issues and demonstrate that covalent attachment of modified spiropyran into a polymeric film significantly reduces photodegradation. The observed signal loss after 12th cycle of switching between the spiropyran and merocyanine forms is only about 27% compared to the loss of 57% of the initial signal in an equivalent experiment based on non-immobilized spiropyran. This has enabled us to demonstrate at least five reversible cycles of detection of an ion of interest (in our case H+) with minimal signal loss. Furthermore, we demonstrate that the sensitivity can be increased by incorporation of additional binding groups in the parent spiropyran molecule. Using molecular modelling to calculate the relevant bond lengths as a measure of interaction between MC and H+, the calculated increase of H-bond strength is approximately an order of magnitude for a derivative containing a methoxy group incorporated in the o-position of the parent spiropyran in comparison to the equivalent unsubstituted phenol. This theoretical result was found to correspond very well with experimental observation. As a result, we have increased the sensitivity to H+ by approximately one order of magnitude.

Item Type:Article (Published)
Refereed:Yes
Uncontrolled Keywords:photoswitch; spiropyran; photodegradation; surface-immobilization; sensor; light-modulation; molecular modelling;
Subjects:Physical Sciences > Photochemistry
Physical Sciences > Analytical chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Research Initiatives and Centres > CLARITY: The Centre for Sensor Web Technologies
Research Initiatives and Centres > National Centre for Sensor Research (NCSR)
Publisher:Elsevier
Official URL:http://dx.doi.org/10.1016/j.jphotochem.2009.05.022
Copyright Information:© 2009 Elsevier B.V.
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:Enterprise Ireland, EI 07/RFP/MASF812, Science Foundation Ireland, SFI 07/CE/I1147
ID Code:4624
Deposited On:24 Jun 2009 10:47 by Aleksandar Radu. Last Modified 29 Apr 2010 13:43

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