The fact that iodine changes color in different solvents due to solvatochromism and donor-acceptor interactions is a standard textbook observation, so no citation is needed.
The claim describes a well-known chemical phenomenon regarding solvatochromism and iodine solution colors (e.g., violet in nonpolar solvents, brown/purple in donor solvents) which is basic chemical common knowledge demonstrated across introductory chemistry curricula.