Synthesis and characterization of hybrid matrix with encapsulated organic sensing dyes for pH sensing application

Sol–gel based optically active phenolphthalein encapsulated nanomatrices for sensing application

“…Comparing the two spectra, it can be seen that the peaks observed between 715 and 840 cm -1 can be ascribed to the vibrational characteristic modes of TiO 2 . A small peak at 730 cm -1 in hybrid matrix sample belongs to Ti-O-Ti stretching [6], whereas a peak observed near 971 cm -1 is associated with Si-O-Ti vibration. The peak around 1076 cm -1 can be associated with the transverse optical vibration mode corresponding to the asymmetric stretching of the intertetrahedral oxygen atoms in the Si-O-Si linkage.…”

“…For ST-phph hybrid sample, the obtained refractive index is 1.58, which lies in between the low silica and high titania refractive indices materials. The light can be strained from silica's lower refractive index material (1.46) to titania's high refractive index material (2.5), which is responsible for strong interaction between the chemical bonds and light [6]. Significantly, this kind of medium refractive index material can be used for multilayered functional coatings and dyesensitized solar cells.…”

“…Even though significant advances in technologies based on sol-gel thin film processing have been reported [1][2][3][4][5][6][7], still relatively little efforts are directed toward understanding the different pH-sensing dyes' immobilization behavior into sol-gelbased silica matrices without leaching problem [8][9][10]. These can be used for designing photocatalysts, for water detection, and also for developing the novel chemical sensor materials [11].…”

Micro- and nanostructured sol-gel-based materials for optical chemical sensing (2005–2015)

“…Materials other than silica have been also investigated. Beltran-Perez et al reported on the evanescent wave absorption pH sensor composed of titania-based sol-gel films doped with different colorimetric indicators [108]. By using a TiO 2 network, the authors aimed to increase the senor lifetime and reported that the pH sensor response was stable over an 8 month period.…”

Mesoporous SiO2–TiO2 nanocomposite for pH sensing

“…This mixture of indicators has spectral similarity in absorption, emission and effective behavior towards the ionic strength. These dyes have valuable properties because of their wide range from near UV to the near-IR regions of the spectrum[18,19]. The characteristics of indicator dyes are summarized in…”