Dimer formation in phthalocyanine-doped sol-gel materials

Peter D. Fuqua; Bruce S. Dunn; Jeffrey I. Zink

doi:10.1117/12.188956

13 October 1994 Dimer formation in phthalocyanine-doped sol-gel materials

Peter D. Fuqua, Bruce S. Dunn, Jeffrey I. Zink

Proceedings Volume 2288, Sol-Gel Optics III; (1994) https://doi.org/10.1117/12.188956
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

Abstract

A number of different organic molecules have been used as optical probes of the sol-gel process. There is relatively little information, however, as to whether these molecules remain well isolated within the sol-gel structure or if they tend to form dimers or higher aggregates within the network. This issue is particularly important for doped sol-gel optical materials as dimer formation can exert a significant influence on the optical properties of dyes. The present paper uses the optical absorption characteristics of copper phthalocyanine tetrasulfonate (CuPcts) to determine how the state of the dye is affected by the chemical changes during the sol-gel process. The absorption spectra of CuPcts indicate that the dye molecules are dimerized in acid-catalyzed silica xerogels prepared from TMOS. The dimerization is largely controlled by the chemical environment inside the pores. By using appropriate reference solutions, we are able to identify the factors which cause dimerization and the stages of the sol-gel-xerogel transformation when the dimers form. These factors include the quantity of solvent remaining in the pores, the alcohol/water content of the solvent and its acidity. It is shown that by modifying the sol-gel processing conditions and the solvent chemistry within the pores, it is possible to reduce significantly dimer formation in silica xerogels.

Citation Download Citation

Peter D. Fuqua, Bruce S. Dunn, and Jeffrey I. Zink "Dimer formation in phthalocyanine-doped sol-gel materials", Proc. SPIE 2288, Sol-Gel Optics III, (13 October 1994); https://doi.org/10.1117/12.188956

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