Multimodal Molecular Logic System: Designed on the Unimolecular Platform of an Intramolecular Charge Transfer-Based...

A novel unimolecular platform based on an intramolecular charge transfer-active hydrazone probe was developed to construct versatile, opto-chemically driven molecular logic devices. The probe exhibited dual-channel responses: a ∼13.5-fold fluorescence quenching at 442 nm with CN^- and a 35 nm red-shift with Hg²⁺. These discrete responses enabled the fabrication of XOR, INHIBIT, and XNOR logic gates at specific wavelengths (440, 355, and 395 nm, respectively), facilitating a molecular half-subtractor and comparator. Time-dependent optical transitions with Cu²⁺ and Hg²⁺ inputs produced dynamic gate switching (TRANSFER to OR, N-TRANSFER to IMPLICATION). Furthermore, multianalyte combinations with F^-, CN^-, and Hg²⁺ enabled the creation of a 3-input, 3-output Boolean circuit. Threshold-guided absorbance (e.g., >0.15 for ON) ensured quantifiable logic states. The reversible nature of ion binding, demonstrated using EDTA, enhances reusability. This work advances tunable, multigate molecular computing for next-generation bio-optoelectronic interfaces.