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.

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