‘To kill many birds with one stone’: Addressing half-adder, half-subtractor, demultiplexer, 2-to-4 decoder, comparator, keypad lock with unimolecular system.

Unimolecular system SBU shows multiple output responses on interaction with Cu 2+ /F − ions individually and simultaneously. The complexation of Cu 2+ with imine ( C N) and OH groups results in blue-shift from 332 to 303 nm and de-protonation of OH group with F − ions causes red-shift of the absorption maxima from 332 to 405 nm. The addition of F − to SBU∩Cu 2+ solution or addition of Cu 2+ to SBU∩F − solution shifts the absorption maxima from 303 to 374 nm or 405–303 nm, respectively. Similarly, the complexation of Cu 2+ ions, inhibits the ESIPT emission at 512 nm with concommitant release of emission at 425 nm, whereas F − results in quenching of emission at 512 nm up to 10 μM, followed by blue-shift to 425 nm at >10 μM F − ions. The addition of F − to SBU∩Cu 2+ solution causes quenching of emission at 512 and 425 nm, whereas addition of Cu 2+ to complex SBU∩F − solution revives the emission at 425 nm considerably. These multiple output response leads to elaboration of YES, NOT, NOR, INH, AND, XOR and XNOR logic gates and Half-adder, Half-subtractor, 2-to-4 decoder, 1:2 demultiplexer, Magnitude Comparator, complimentary OR/NOR circuit and molecular keypad lock logic circuits. [ABSTRACT FROM AUTHOR]