Zinc(II) and Cadmium(II) Complexes Derived from 4 '-(2-Pyridyl)-2,2 ':6 ',2 ''-terpyridine: Crystal Structures and Fluorescence Property

Complexes [Zn(2-pyterpy)(2)](ClO4)(2)center dot 0.25H(2)O (1) and [Cd(2-pyterpy)(2)](2)(ClO4)(4)center dot 2.33H(2)O center dot CH3OH ( 2) (2-pyterpy=4'-(2-pyridyl) -2,2':6',2 ''-terpyridine) were synthesized under solvothermal conditions, and structurally characterized by elemental analysis, FT-IR spectra, X-ray single crystal diffraction and powder X-ray diffraction. X-ray single crystal diffraction results show that they crystallize in the triclinic system with the P1 space group. In solid-state, complexes 1 and 2 showed the maxima emission band approximately at 539 and 547 nm upon excitation at 405 nm, respectively. In methanol solution, complexes 1 and 2 exhibited emissions at 408 and 371 nm upon excitation at 357 and 352 nm, respectively. The metastable-state photoacid mPAH1 showed fluorescence at 556 nm upon excitation at 467 nm. When complex 1 was titrated with mPAH1, the fluorescence of complex 1 at 408 nm was quenched by mPAH1 with a quenching constant K-SV of 2.961x10(4) L center dot mol(-1), but the fluorescence lifetime of complex 1 remained nearly unchanged, which is attributed to the inner filter effect. Conversely, titration of mPAH1 with complex 1 resulted in enhanced fluorescence of the mixed solution at 556 nm, which is attributed to partial protonation of complex 1 by mPAH1. CCDC: 2149901, 1; 2149905, 2.