Zn2+ selective luminescent ‘off–on’ probes derived from diaryl oxadiazole and aza-15-crown-5
作者:Sabir H. Mashraqui、Subramanian Sundaram、Tabrez Khan、A.C. Bhasikuttan
DOI:10.1016/j.tet.2007.08.031
日期:2007.11
New photo-induced electron transfer ( PET) probes OMOX and OBOX, carrying an additional binding site in the form of 'oxadiazole nitrogen' have been designed to evaluate binding interactions with biologically significant Li+, Na+, K+, Ca2+, Mg2+, and Zn2+ including environmentally toxic Ba2+ and Cd2+ using optical spectral techniques. While Li+, Na+, and K+ did not appreciably perturb either the absorption or emission spectra, Ba2+, Ca2+, Mg2+, Zn2+, and Cd2+ induced slight red shifts (2-8 nm) in the UV-visible spectra as well as pronounced chelation induced enhanced fluorescence ( CHEF). Both OMOX and OBOX exhibited the highest CHEF in contact with the zinc ion, whereas Ba2+, Ca2+, Mg2+, and Cd2+ induced relatively less emission enhancements. OBOX, which is a poorer emitter (Phi(f) = 0.0062) than OMOX (Phi(f) = 0.015), showed highly promising 160-fold emission enhancement in the presence of Zn2+. Potential, therefore is available in OBOX to function as a selective luminescent 'off-on' sensor for Zn2+ in the presence of coordinatively competing Ba2+, Ca2+, Mg2+, and Cd2+ ions. (c) 2007 Elsevier Ltd. All rights reserved.