Highly selective thioalcohol modified phthalocyanine sensors for Ag(i) and Pd(ii) based on target induced J- and H-type aggregations: synthesis, electrochemistry and peripheral metal ion binding studies
Abstract
We have described highly selective 1(4),8(11),15(18),22(25)-(1-hydroxyhexan-3-ylthio)-phthalocyanine sensors, M{Pc[α-SCH(C3H7)(C2H5OH)]4} (MPc(α-HHT)4, where M = Zn(II) (2), Cu(II ) (3) or Co(II ) (4) and HHT: –SCH(C3H7)(C2H5OH)). The formation of S–M–S {S = sulfur; M = Ag(I) or Pd(II)} bonds on the periphery in the case of Ag(I) and Pd(II) metal ions induces H- or J-aggregation, respectively, which results in significant changes in the absorption of the B- and, in particular, the Q-band. The binding ratios of Ag(I) to the periphery of 2 and 3 were found to be ca. 2 : 1 and 3 : 2, respectively. On the other hand, the binding ratios of Pd(II) to the periphery of the same compounds were found to be 3 : 1 and 4 : 1. The fluorescence of 2 exhibited distinct changes in response to treatment with Ag(I) and Pd(II) ions in solution. The fluorescence spectra emission intensity of 2 was quenched upon