Scarmagnani, Silvia, Walsh, Zarah, Slater, Conor, Alhashimy, Nameer, Macka, Mirek, Paull, Brett and Diamond, Dermot ORCID: 0000-0003-2944-4839 (2008) Polystyrene bead-based system for optical sensing using spiropyran photoswitches. Journal of Material Chemistry, 18 . pp. 5063-5071. ISSN 1364-5501
Abstract
Spiropyran derivatives have been immobilised on the surface of polystyrene microbeads using different
immobilisation strategies. These functionalised polymeric beads can be reversibly switched between the
colourless inactive spiropyran (SP) and highly coloured (purple) active merocyanine (MC) forms using
low power light sources, such as light-emitting diodes (LEDs). A UV LED (375 nm) is used for the SP
/MC conversion, and a white LED (430–760 nm) for the reverse MC/ SP conversion. The
photochromic behaviour of the coated beads has been characterised using different LEDs and
reflection spectroscopy, employing optic fibres and an in-house-designed holder. Investigations into the
metal-ion binding behaviour of the spiropyran-modified microbeads have shown that Cu2+ ions cause
an appreciable colour and spectral change when brought into contact with the beads in the MC form,
suggesting that a significant interaction is occurring. However, the Cu2+ ions can be completely expelled
by photonic-conversion of the beads into the inactive SP form using a white LED. This sequence has
been successfully repeated six times, suggesting that it is possible to cycle through activation of the
functionalised beads from a non-binding to a binding form (SP / MC) using a UV LED, allow
binding with Cu2+ ions to occur, and subsequently, expel the bound ions and regenerate the passive SP
surface using a white LED. Other metals, such as calcium, do not cause any appreciable colour or
spectral change over the same concentration range and in the presence of the same anion (final
concentration 7.1 104 M nitrate salt in ethanol). The system is therefore self-indicating in terms of
whether the active MC or inactive SP forms are present, and whether Cu2+ ions are bound to the MC
form. In principle, therefore, these functionalised beads could form the basis of a photoswitchable
stationary phase for metal ion binding and detection: irradiation of the stationary phase with UV LEDs
causes retention of guest species due to the presence of the MC form, while subsequent exposure to
white LEDs causes release of guest species into the mobile phase
Metadata
Item Type: | Article (Published) |
---|---|
Refereed: | Yes |
Subjects: | Physical Sciences > Chemistry |
DCU Faculties and Centres: | DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences Research Institutes and Centres > National Centre for Sensor Research (NCSR) |
Publisher: | Royal Society of Chemistry |
Official URL: | http://dx.doi.org/10.1039/b810080b |
Use License: | This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License |
ID Code: | 661 |
Deposited On: | 18 Aug 2009 13:52 by Silvia Scarmagnani . Last Modified 18 Sep 2018 13:11 |
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