1：Experimental Design and Method Selection:

The study involved the synthesis of a quinoxaline-based probe Q1 and its characterization using spectroscopic techniques. The proton sensing properties were monitored through UV-vis and fluorescence spectroscopy.

2：Sample Selection and Data Sources:

The receptor Q1 was synthesized and its protonation and deprotonation states were studied in dichloromethane solutions.

3：List of Experimental Equipment and Materials:

UV-vis absorption experiments were performed in a quartz cell with a 1 cm path length. Fluorescence spectra were measured on a RF-6000 spectrofluorophotometer. Time resolved fluorescence studies were carried out by the time correlated single photon counting technique.

4：Experimental Procedures and Operational Workflow:

The UV-vis and fluorescence spectra of Q1 were recorded with increasing concentrations of TFA. The reversibility of the receptor was tested by adding TEA.

5：Data Analysis Methods:

The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations.