Detection of cationic guest molecules by quenching of luminescence of a self-assembled host molecule consisting of terbium(III) and calix[4]arene-p-tetrasulfonates

By self-assembly in aqueous solution, calix- (CAS) and thiacalix[4]arene-p-tetrasulfonate (TCAS) formed luminescent complexes Tb-III.(CAS)(2) and Tb-III.TCAS, respectively, which were utilized as a host for cationic guests. Addition of 1-ethylpyridinium guest quenched luminescence of Tb-III.(CAS)2 in accordance with the Stern-Volmer (SV) relation with a low detection limit (D.L.) of 5.94 x 10(-8) M (S/N=3, M equivalent to mol dm(-3)). On the other hand, 1-ethylquinolinium quenched luminescence of Tb-III.TCAS most efficiently, affording a very low D.L. (6.71 x 10(-10) M). The agreement of the SV coefficients obtained with luminescent intensity (K-SV.all = 6.74 x 10(6) M-1) and lifetime (K-SV.Tb = 6.50 x 10(6) M-1) implied that dynamic quenching of D-5(4) excited state of Tb-III was predominant in the quenching processes. The quenching rate was estimated to be k(q.Tb) = 9.94 x 10(9) M-1 s(-1), which was as fast as diffusion-limited rate. Quenching of Tb-III.(CAS)(2) was also applied to detection of NAD*, with a D.L. of 2.78 x 10(-7) M. (C) 2009 Elsevier B.V. All rights reserved.