Complexes of tetramethylensulfonatocalix[4]resorcinarene aggregates with methyl orange: Interactions with guests and driving force of color response

• Binding of guests generates color response of colloidal system resorcinarene–dye.
• It is due to displacement of dye and due to variation of aggregate dimensions.
• The latter gives a contribution to the change of the surface-bound dye protonation.

Here we report on the examination of 12 guests (G1–12) interactions with the aggregates of tetramethylensulfonated tetrapentylcalix[4]resorcinarene (H) and the azo-pH-indicator methyl orange (MO). At pH 4.2, addition of 40 and 100 equiv. of the guests to 40:1 H:MO solution resulted in deprotonation of the dye accompanied by UV/Vis spectra changes. Variation of MO deprotonation degree in the presence of G1–12 is discussed in relation to the guest interactions with the aggregated H and competition with the surface-bound MO.

Figure optionsDownload as PowerPoint slide