Design, synthesis and pH switching effects of the intramolecular charge transfer (ICT) dye sensor chromophore prepared by the coupling reaction of 6-methoxy-2-aminobenzothiazole (donor moiety) with 4-nitroaniline (acceptor moiety) were carried out and discussed. Optical absorption properties were monitored with the addition of increasing alkali/acid equivalence. In this determination, the prepared pH dye sensor chromophore showed reversible optical switching functions. The levels of energy potential and the electron density distribution of this dye sensor such as HOMO and LUMO values were calculated by computational simulation approaches using Material Studio 4.3. The functions of molecular switching sensor with pH stimulation of alkali-acid addition were determined in DMSO:$H_2O$, which was operated by deprotonation/protonation effects based on ICT system.