Molecular half-subtractor based on 3,3′- bis(1H-benzimidazolyl-2-yl)[1,1′]-binaphthalenyl-2,2′-diol

Title fluorophore (1) possessing 2,2'-binaphthol and benzimidazole moieties has been investigated for elaboration of half-subtractor logic operation. For comparison differently substituted systems have been studied. Fluorophore 1 showed strong fluorescence at 585 nm due to ESIPT phenomena which was completely quenched on addition of HClO4 with concomitant appearance of a new emission band at 435 nm with hypsochromic shift of 150 nm. The addition of TBAOH to the solution of 1 gave a new hypsochromically shifted emission band at 515 nm (Delta lambda = 70 nm) with concomitant quenching at 585 nm. Thus, fluorophore 1 with large differentials of emission maxima under neutral, acidic and basic conditions provides four opportunities for arithmetic operation half-subtractor. i.e. with 435/515 nm (INHIBIT) and 475 nm (XOR) gates and with 435/515 nm (INHIBIT) and 585 nm (XNOR) gates which have been elaborated as combinatorial logic circuits for a molecular half-subtractor with acid and base as input variables. The elaboration of half-subtractor with only XOR logic in the case of fluorophore 2 possessing a molecular structure half that of fluorophore 1 and complete lack of logic gates in fluorophore 5 with change in position of benzimidazole moiety further signify the importance of the structural architecture in fluorophore 1.