Chemosensor L showed a nonlinear fluorescence response on specific binding to Cr³⁺ ion in the presence of various alkali, alkaline-earth, transition, and lanthanide metal ions. A luminescence band with maxima at 512 nm for L was observed (λ_ext = 330 nm) for a twisted intramolecular charge transfer (TICT) transition following antienergy gap law behavior. However, normal energy gap law behavior prevailed on formation of a new nonluminescent charge transfer complex, Mⁿ⁺·L. For paramagnetic metal ions, paramagnetism induced luminescence quenching could have also contributed to this. A new switched on fluorescence response at λ_ems of 356 nm (λ_ext of 330 nm) was observed due to Franck–Condon charge transfer (FC-CT) transition only on the formation of a complex, (Cr³⁺)₂·L. Spectral studies revealed a unique dynamic coordination behavior and migration of Cr³⁺ from the terpyridyl fragment to the N_NMe2 center of L as a function of the varying concentration of another ion (Zn²⁺) and the subtle difference in the binding affinities of the terpyridyl moiety toward Cr³⁺ and Zn²⁺. Further, spectral responses of L toward Zn²⁺, different concentration of Cr³⁺, H⁺ and on subsequent addition of F^– as different ionic inputs could be correlated well for demonstrating various basic and combinatorial circuits.