1：Experimental Design and Method Selection:

The study uses x-ray diffraction and visible light absorption spectroscopy to investigate the nematic and isotropic phases of aqueous solutions of a perylene dye. Theoretical models include isodesmic assembly and exciton coupling theory to analyze the data.

2：Sample Selection and Data Sources:

Aqueous mixtures of Bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride (PDI-HCl) were prepared with concentrations ranging from 0.00001 to 0.00035 wt% for absorption measurements and higher concentrations for x-ray diffraction. Samples were loaded into rectangular capillaries and sealed.

3：00001 to 00035 wt% for absorption measurements and higher concentrations for x-ray diffraction. Samples were loaded into rectangular capillaries and sealed. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a Bruker-Nonius FR591 x-ray generator with mirror-monochromater optics and a multiwire detector, an Agilent Technologies Cary 60 uv-vis spectrophotometer, an Instec HC5302 heating stage, and a Leitz Laborlux 12 Pol microscope. Materials include PDI-HCl, quartz capillary tubes, and epoxy for sealing.

4：Experimental Procedures and Operational Workflow:

Mixtures were stirred and heated at 80°C until dissolved, loaded into capillaries at 80°C, sealed, and mounted on microscope slides. Temperature was controlled for phase observation. X-ray diffraction was performed at room temperature with water background subtraction. Absorption measurements were taken over 400–700 nm wavelengths with path lengths from 10 to 100 mm, subtracting water absorption.

5：Data Analysis Methods:

X-ray data were analyzed by integrating over azimuthal angle and fitting peaks to Lorentzian functions. Absorption spectra were decomposed into Lorentzian bands and fit using exciton coupling theory and isodesmic assembly models to determine free energy changes and assembly sizes.