Synthesis and spectroscopic characterisation of fluorescent indicators for Na+ and K+ based on (di)pyridino crown ethers
作者:Abdellah Tahri、Els Cielen、Koen J. Van Aken、Georges J. Hoornaert、Frans C. De Schryver、Noël Boens
DOI:10.1039/a901941c
日期:——
The synthesis and the spectral and cation binding properties of a fluorescent indicator for Na+, caesium 5-5-[3,6,9,12-tetraoxa-18-azabicyclo[12.3.1]octadeca-1(18),14,16-trien-16-yl]-2-thienyl}isophthalate (SPYR), and of two fluorescent indicators for K+, caesium 5-5-[3,6,9,12,15-pentaoxa-21-azabicyclo[15.3.1]henicosa-1(21),17,19-trien-19-yl]-2-thienyl}isophthalate (PPYR) and dicaesium 5-5-[21-(5-1-[3,5-di(caesiooxycarbonyl)phenyl]}-2-thienyl)-3,6,14,17-tetraoxa-23,24-diazatricyclo[17.3.1.18,12]tetracosa-1(23),8(24),9,11,19,21-hexaene-10,21-diyl]-2-thienyl}isophthalate (BIPY) are reported. To investigate the effect of an sp2-nitrogen in the aza-crown ether cavity on the complex formation behaviour, a (bi)pyridino crown compound with an appropriate cavity for the sodium and the potassium cation, respectively, is linked to an aryl thiophene fluorophore. New, versatile routes for the synthesis of 4-substituted pyridino crown ethers and 4,4′-substituted sym-dipyridino crown ethers are described. The chelating abilities of the indicators with monovalent cations have been studied in aqueous solution by their fluorescence properties. Both the free and complexed forms of the indicators have an absorption maximum around 345 nm and an emission maximum at 410 nm, displaying only a decrease in the fluorescence intensity upon cation binding. While SPYR cannot discriminate between Na+ and other monovalent cations, PPYR and BIPY show a peak selectivity for K+ with a dissociation constant of 1.2 ± 0.3 mM and 4.4 ± 0.7 mM, respectively.
报道了荧光钠指示剂铯5-5-[3,6,9,12-四氧杂-18-氮杂双环[12.3.1]十八烷-1(18),14,16-三烯-16-基]-2-噻吩基}异酞酸酯(SPYR)以及两种荧光钾指示剂铯5-5-[3,6,9,12,15-五氧杂-21-氮杂双环[15.3.1]二十一烷-1(21),17,19-三烯-19-基]-2-噻吩基}异酞酸酯(PPYR)和二铯5-5-[21-(5-1-[3,5-二(铯氧羰基)苯基]}-2-噻吩基)-3,6,14,17-四氧杂-23,24-二氮杂三环[17.3.1.18,12]四十二烷-1(23),8(24),9,11,19,21-六烯-10,21-二基]-2-噻吩基}异酞酸酯(BIPY)的合成与光谱和阳离子结合特性。为了研究aza-冠醚腔中的sp2-氮对配位行为的影响,分别将适合钠和钾阳离子的(双)吡啶冠醚化合物与苯并噻吩荧光团相连。描述了4-取代的吡啶冠醚和4,4′-取代的对称-二吡啶冠醚的新颖合成路线。通过其荧光性质在水中研究了这些指示剂与一价阳离子的配位能力。指示剂的自由形式和配合形式在345 nm处均有最大吸收峰,在410 nm处有最大发射峰,仅在阳离子结合时荧光强度降低。虽然SPYR无法区分Na+和其他一价阳离子,但PPYR和BIPY显示对K+具有峰选择性,其解离常数分别为1.2±0.3 mM和4.4±0.7 mM。