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A new iminocoumarin based receptor L (C(27)H(26)N(4)OS) is synthesized with pyridyl and benzothiazolyl functionality. Synthesis of L is easy and it is isolated in good yield. L shows a selective and distinct color change from yellow to orange with Cu(2+) over Li(+), Na(+), Ca(2+), Mg(2+), Cr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), and Ag(+) whereas a slight change in color is also observed in the case of Hg(2+) but L shows selective fluorescent quenching only in the presence of Cu(2+) in aqueous HEPES buffer (pH 7.0). The naked eye detection limit of Cu(2+) is determined at 2 μM whereas an emission experiment shows a lower detection limit at 200 nM. Selectivity studies of L in presence of 50 equivalents of other ion(s) by emission experiment show no interference toward the detection of 1 equivalent of Cu(2+). Both UV-Vis and fluorescence studies in the presence of Cu(2+)-salts of different counter anions with various sizes and shapes (Cl(-), ClO(4)(-), NO(3)(-), CF(3)SO(3)(-), SO(4)(2-) and BF(4)(-)) show almost similar spectral output in buffer media irrespective of the nature of the counter anions. The detailed UV-Vis and fluorescence titration experiments suggest the existence of both 1:1 and 2:1 (L:Cu(2+)) complexation stoichiometry and EPR study shows d(x(2)-y(2)) ground state of the Cu(II) centre in the complex. Furthermore the formation of a mononuclear [Cu(L)(CH(3)CN)].2ClO(4) complex and the flexible conformation of L in the solid state are confirmed by the single-crystal X-ray structural study., (This journal is © The Royal Society of Chemistry 2011)

A new iminocoumarin based receptor L(C27H26N4OS) is synthesized with pyridyl and benzothiazolyl functionality. Synthesis of Lis easy and it is isolated in good yield. Lshows a selective and distinct color change from yellow to orange with Cu2ꋷ Li, Na, Ca2, Mg2, Cr2, Mn2, Fe2, Co2, Ni2, Cu2, Zn2, Cd2, Pb2, and Ag숗ꭹ a slight change in color is also observed in the case of Hg2滫 Lshows selective fluorescent quenching only in the presence of Cu2 aqueous HEPES buffer (pH 7.0). The naked eye detection limit of Cu2 determined at 2 μM whereas an emission experiment shows a lower detection limit at 200 nM. Selectivity studies of Lin presence of 50 equivalents of other ion(s) by emission experiment show no interference toward the detection of 1 equivalent of Cu2. Both UV-Vis and fluorescence studies in the presence of Cu2+salts of different counter anions with various sizes and shapes (Cl−, ClO4−, NO3−, CF3SO3−, SO42−and BF4−) show almost similar spectral output in buffer media irrespective of the nature of the counter anions. The detailed UV-Vis and fluorescence titration experiments suggest the existence of both 1 : 1 and 2 : 1 (L : Cu2) complexation stoichiometry and EPR study shows dx2–y2ground state of the Cu(ii) centre in the complex. Furthermore the formation of a mononuclear [Cu(L)(CH3CN)].2ClO4complex and the flexible conformation of Lin the solid state are confirmed by the single-crystal X-ray structural study. [ABSTRACT FROM AUTHOR]