Molecular Full-adder and Full-subtractor Logic Circuit Based on Fluorescein Derivatives

Over the past decade, there has been significant progress in the development of molecular computer, which has inspired scientists to construct appropriate molecular systems that could integrate simple logic gates into combinatorial circuits. In this work, a novel fluorescein-based QHF(+) with five-state molecular switch was synthesized. The conversion of the five states of QHF(+) was observed by UV-visible absorption spectra under various pH values in CH3CH2OH/H2O(volume ratio 1:1). Spectral responses with the use of chemical inputs in the form of H+ and OH- revealed that QHF could function as a combinatorial logic circuit (XOR gate and INHIBIT gate, AND gate and XOR gate). Absorbance change at 424 and 490 nm or transmittance change at 424 nm, was monitored as output signals with threshold value of A =0. 209 (or T=61. 8%). When absorbance intensity or transmittance percentage was more than the threshold value, the output signal was 1. Otherwise, the output value was 0. In conclusion, a full-subtractor was achieved by setting the initial state to QHF(0) with outputs at 424 and 490 nm in the absorption mode, while a molecular full-adder was provided by setting the initial state to QHF(+) and observing both absorbance at 490 nm and transmittance at 424 nm.