By self-assembly in aqueous solution, calix- (CAS) and thiacalixarene-p-tetrasulfonate (TCAS) formed luminescent complexes TbIII·(CAS)2 and TbIII·TCAS, respectively, which were utilized as a host for cationic guests. Addition of 1-ethylpyridinium guest quenched luminescence of TbIII·(CAS)2 in accordance with the Stern-Volmer (SV) relation with a low detection limit (D.L.) of 5.94 × 10-8 M (S/N = 3, M ≡ mol dm-3). On the other hand, 1-ethylquinolinium quenched luminescence of TbIII·TCAS most efficiently, affording a very low D.L. (6.71 × 10-10 M). The agreement of the SV coefficients obtained with luminescent intensity (KSV,all = 6.74 × 106 M-1) and lifetime (KSV,Tb = 6.50 × 106 M-1) implied that dynamic quenching of 5D4 excited state of TbIII was predominant in the quenching processes. The quenching rate was estimated to be kq,Tb = 9.94 × 109 M-1 s-1, which was as fast as diffusion-limited rate. Quenching of TbIII·(CAS)2 was also applied to detection of NAD+, with a D.L. of 2.78 × 10-7 M.
- Host-guest systems
- Luminescence detection
- Nicotineamide adenine dinucleotide