Design and synthesis of intramolecular hydrogen bonding systems. Their application in metal cation sensing based on excited-state proton transfer reaction

[摘要] We reported the design and synthesis of a new type of metal-cation probes, 3-hydroxy-4-(1,4,7,10-tetraoxa-13-azacyclopentadec-13-ylmethyl)naphthalene-2-carbaldehyde (1a) and its single hydrogen-bond analogue 1-(1,4,7,10-tetraoxa-13-azacylopentadec-13-ylmethyl)-2-naphthol (2a), in which 1-aza-15-crown-5 ether in combination with the naphthol oxygen acts as a receptor, while the mechanism of excited-state intramolecular proton transfer (ESIPT) is exploited as a signal transducer. The association constant of (2.5 +/- 0.5) X 10(4), (3.8 +/- 0.4) X 10(4), (5.5 +/- 0.5) X 10(3) and (1.2 +/- 0.3) X 10(4) M-1 for the formation of 1a/Na+ , 1a/Ca2+, 2a/Na+ and 2a/Ca2+ complexes, respectively, in CH3CN plus drastic fluorescence changes due to the fine-tuning of ESIPT reaction upon complexation, lead la and 2a to be highly sensitive fluorescent sensors. The results add a new class into the category of metal-cation probes, with the perspective of designing ESIPT systems capable of sensing bio-analytes. (C) 2004 Elsevier Ltd. All rights reserved.

[发布日期] 2004-12-13

[关键词] hydrogen bonding;metal-cation probes;excited state intramolecular proton transfer reaction;receptors