A Triethylenetetramine Bearing Anthracene and Benzophenone as a Fluorescent Molecular Logic Gate with Either−Or Switchable Dual Logic Functions.

Fluorescence behaviors of a triethylenetetramine bearing anthracene (AN) and benzophenone (BP) fragments at the respective ends, L1, have been studied in water, where effects of pH (H) and metal cations on the emission properties have been studied in detail. L1behaves as a fluorescent molecular logic gate driven by H(Input1) and metal cations (Input2) as input chemicals. The most notable feature of L1is that this molecule expresses the “either−or” switchable dual logic functions. Operation of L1with Cu2as Input2expresses the INHIBIT logic function, where a strong AN fluorescence appears only at pH 4 (with H) without Cu2Input1(1)-Input2(0). In contrast, operations of L1with all other metal cations as Input2express the TRANSFER logic function, where the presence of Hallows strong AN fluorescence regardless of whether the metal cation exists or not Input1(1)-Input2(0); Input1(1)-Input2(1). These emission switching behaviors of L1are driven by the difference in the coordination stability between L1and metal cations and the photoinduced intramolecular electron and energy transfer processes:  (i) a pH-induced electron transfer from unprotonated nitrogen atoms of the polyamine chain to the photoexcited AN ELT(N→AN); (ii) a pH- and metal coordination-induced electron transfer from the photoexcited AN to the ground-state BP ELT(AN→BP); and (iii) a Cu2coordination-induced energy transfer from the photoexcited AN to Cu2ENT(AN→Cu2). [ABSTRACT FROM AUTHOR]