Highly effective water-soluble fluorescence quenchers of conjugated polymer thin films in aqueous environments

Macromolecules

Volumn 39, Issue 21, 2006, Pages 7175-7177

  Joly, Guy D ^a   Geiger, Lars ^a   Kooi, Steven E ^a   Swager, Timothy M ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

HYDROPHOBIC INTERACTIONS; SENSORY SYSTEMS; SOLID-STATE DEVICES; VIOLOGEN QUENCHERS;

COMPLEXATION; ELECTROLYTES; FLUORESCENCE; HYDROPHOBICITY; ORGANIC POLYMERS; QUENCHING;

THIN FILMS;

EID: 33751313880     PISSN: 00249297     EISSN: None     Source Type: Journal    
DOI: 10.1021/ma061618h     Document Type: Article

References (29)

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6. 7 in aqueous solution, see: (a) Reference 2a.
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15. PPEs 1 (ref 9) and 3 (ref 12c) have been previously reported. For the preparation of PPE 2, see the Supporting Information.
16. Crown ethers are excellent hosts for viologens. See: Allwood, B. L.; Shahriari-Zavareh, H.; Stoddart, J. F.; Williams, D. J. J. Chem. Soc., Chem. Commun. 1987, 1064.
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19. For the synthesis of viologens 5-8, see the Supporting Information.
20. THF was required to solubilize PPE 1, as PPE 1 is not soluble in aqueous Tris buffer alone.
21. For previous studies involving fluorescence quenching of Langmuir-Blodgett films of 1 in organic solvents, see: (a) Levitsky, I. A.; Kim. J.; Swager, T. M. J. Am. Chem. Soc. 1999, 121, 1466.
22. (b) Levitsky, I. A.; Kim, J.; Swager, T. M. Macromolecules 2001, 34, 2315. For additional previous studies involving Langmuir-Blodgett films of 3, see:
23. (c) Kim, J.; Swager, T. M. Nature (London) 2001, 411, 1030.
24. Stern-Volmer constants for LB monolayers were obtained from a linear fit of the data at low quencher concentration where the Stern-Volmer plot is linear. As quencher concentration increased, the quenching responses of LB monolayers exhibited downward curvature due to overlapping quenching spheres at high quencher concentration. See the Supporting Information for the linear portion of the Stern-Volmer responses of the LB monolayers.
25. Thin film optimization revealed no significant dependence of sensitivity or stability upon the nature of the substrate (hydrophobic vs hydrophilic), surface pressure at which the LB films were deposited, or dipping direction. The most important factor was layer thickness; the best stability was achieved with monolayer films. Thicker films proved to be too unstable upon exposure to aqueous buffer as emission from these films trends down with time. See the Supporting Information.
26. This work was guided by the hypothesis that hydrophobic functionalization of the viologen quencher would decrease the water solubility of the quencher, thereby facilitating desolvation of the quencher upon binding to the hydrophobic polymer. Increased quencher hydrophobicity should increase the driving force for the viologen quencher to come out of aqueous solution and into the hydrophobic polymer thin film.
27. For conjugated polymer-based protease sensors, see: (a) Wosnick, J. H.; Mello, C. M.; Swager, T. M. J. Am. Chem. Soc. 2005, 127. 3400.
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