9-(cycloheptatrienylidene)-fluorene derivative: remarkable ratiometric pH sensor and computing switch with NOR logic gate.

2,7-Bis(4-dimethylaminophenyl)-9-(cycloheptatrienylidene)fluorene (1) was synthesized and characterized. 1 could be used as a fluorescent sensor either for pH or for pyridinium halide. Integrated with the ratiometric method and an NOR logic gate, a tunable two-input/multi-output system was presented on the basis of this single molecule. [structure: see text]