Triphenylamine-based pH chemosensor: Synthesis, crystal structure, photophysical properties and computational studies

A triphenylamine-containing pH chemosensor, N,N'-di[3-(diphenylamine)benzyl]-piperazine, was designed and synthesized with Ullmann reaction. The compound crystallize in the monoclinic space group P21/n: a=9.8004(12)angstrom, b=13.3321(17)angstrom, c=12.9575(16)angstrom, beta=103.510(2)degrees, V=1646.2(4)angstrom(3), Z=2 and rho = 1.212 Mg/m(3). The synthesized compound excited by UV light produce intensive emission and a quantum yield of 0.56 relative to quinine sulfate was achieved. The fluorescence intensity of synthesized compound in water/DMF (4:1, v/v) under excitation of 307 nm decreased with the decrease of pH, experimental and computational studies further confirmed that the protonation of N-triphenylamine leads to the fluorescence quenching. The results clearly indicate the potential of synthesized compound as highly efficient on-off switcher for protons. (C) 2009 Elsevier B.V. All rights reserved.