Synthesis and photochemistry of a new benzothiazolinic oxazine salt and its application in the detection of hydrogen sulfate ion

•A salt form of new photochromic benzothiazole oxazine was synthesized and characterized.•Single crystal X-ray crystallography validated structure and intermolecular interactions.•The benzothiazole oxazine salt converted to closed to its closed form under UV light.•The benzothiazolinic oxazine in the salt form detected the presence of hydrogen sulfate ions.•Computational studies established the greater stability of the complex compared to the closed form.