Photo-switchable surfaces: a new approach to chemical sensing

Aleksandar Radu; Silvia Scarmagnani; Robert Byrne; Conor Slater; Nameer Alhashimy; Dermot Diamond

doi:10.1117/12.737098

29 October 2007 Photo-switchable surfaces: a new approach to chemical sensing

Aleksandar Radu, Silvia Scarmagnani, Robert Byrne, Conor Slater, Nameer Alhashimy, Dermot Diamond

Proceedings Volume 6749, Remote Sensing for Environmental Monitoring, GIS Applications, and Geology VII; 67491Z (2007) https://doi.org/10.1117/12.737098
Event: SPIE Remote Sensing, 2007, Florence, Italy

Abstract

Here, we discuss an interesting concept that brings an added flexibility in chemo/bio sensing. We present system that can be switched photonically between two states, only one of which exhibits ion-binding behaviour. The system is based on molecular photoswitch spiropyran, which is probably the most studied compound exhibiting above characteristics. Upon irradiation with UV light the passive spiropyran (SP) molecule undergoes a heterocyclic ring cleavage that results with the formation of the merocyanine (MC) which is zwitterionic form capable of ion binding. In contrast to the uncharged and colourless spiropyran form, the merocyanine form is highly charged and can be utilized as ligand for other charged species. Moreover, it is strongly coloured, and the colour tells us which form is present. In addition it provides interesting information about the immediate environment of the merocyanine binding site (e.g. polarity, presence of certain ions etc.). In this work, we present a SP-based system in which SP is immobilized and protected within a polymeric matrix. Such system may be used for detection of metal ions in highly polar solvents, e.g. water. The response characteristics and kinetics of MC-Cr³⁺ complex formation and SP-MC switching within the polymer matrix have been determined. Simple light emitting diodes (LEDs) have been employed for photoswitching and colorimetric measurement of SP-MC switching and MC-Cr³⁺ complex formation as light sources and detectors.

Citation Download Citation

Aleksandar Radu, Silvia Scarmagnani, Robert Byrne, Conor Slater, Nameer Alhashimy, and Dermot Diamond "Photo-switchable surfaces: a new approach to chemical sensing", Proc. SPIE 6749, Remote Sensing for Environmental Monitoring, GIS Applications, and Geology VII, 67491Z (29 October 2007); https://doi.org/10.1117/12.737098

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