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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. L1 behaves as a fluorescent molecular logic gate driven by H+ (Input1) and metal cations (Input2) as input chemicals. The most notable feature of L1 is that this molecule expresses the "either-or" switchable dual logic functions. Operation of L1 with Cu2+ as Input2 expresses the INHIBIT logic function, where a strong AN fluorescence appears only at pH 4 (with H+) without Cu2+ [Input1(1)-Input2(0)]. In contrast, operations of L1 with all other metal cations as Input2 express the TRANSFER logic function, where the presence of H+ allows 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 L1 are driven by the difference in the coordination stability between L1 and 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 Cu2+ coordination-induced energy transfer from the photoexcited AN to Cu2+ [ENT(AN*--Cu2+)].

[reaction: see text] A simple-structured molecule (L1) bearing anthracene fragments at both ends of diethylenetriamine chain behaves as a fluorescent molecular switch with pH-controlled absolutely switchable dual-mode fluorescence in water; each mode consists of monomer (pH9) and excimer (pH9) emissions.

N-(9-Anthrylmethyl)-1,4,7,10-tetraazacyclododecane (AC), which acts as an efficient fluorescent chemosensor for detection of pH and metal cations in aqueous solution, was covalently grafted on a Na...

The extraction and separation of transition metals has been investigated using several inorganic adsorbents (silica gel, MCM-41, and aluminum oxide), modified with ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) as chelating ligands. The metal ions in aqueous solution were coordinated successfully by the ligands on the surface of the adsorbents under moderate conditions. Metal−ligand complexes formed on the adsorbents effectively in the region of low pH (1−2) but scarcely formed at pH > 4. Silica gel modified with EDTA (silicaED) was shown to be the most effective adsorbent for the extraction of metals and to form specific metal−EDTA complexes, with stability constants lying in the order Cu2+ > Ni2+ > VO2+ > Zn2+ > Co2+ > Mn2+. The relatively good separation of these six adjacent metals was therefore also carried out using the silicaED. The metals coordinated on the silicaED could be desorbed completely by putting the material into contact with 1 mol/L aqueous HCl solu...