Three novel aza-crown ether derivatives incorporating 4-amino-7-nitrobenzaoxa-1,3-diazole (NBD) chromophore were synthesized and their structure confirmed by 1H-NMR, IR and elemental analysis. The influence of the solvent polarity and protonation on the photophysical properties of NBD-15-crown-5 was studied by UV/Vis and fluorescence methods. The influence of the investigated cations on the absorption spectra of the ligands was negligible, however emission was strongly affected. Complexation and binding stability of NBD-aza-15-crown-5 and NBD-aza-18-crown-6 were studied using fluorescence spectroscopy. NBD-aza-18-crown-6 exhibits strong selectivity toward Ca2+ and Sr2+ ions with formation constants about 103 times higher than the formation constants with the other ions included in the study.

中文翻译：

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N-(4-amino-7-nitrobenzaoxa-1,3-diazole)-取代的氮杂冠醚：与碱、碱土金属离子和铵络合

合成了三种新型氮杂冠醚衍生物，其中包含 4-amino-7-nitrobenzaoxa-1,3-diazole (NBD) 发色团，并通过 1H-NMR、IR 和元素分析证实了它们的结构。通过UV/Vis和荧光方法研究了溶剂极性和质子化对NBD-15-crown-5光物理性质的影响。所研究的阳离子对配体吸收光谱的影响可以忽略不计，但发射受到强烈影响。使用荧光光谱研究了 NBD-aza-15-crown-5 和 NBD-aza-18-crown-6 的复合和结合稳定性。NBD-aza-18-crown-6 对 Ca2+ 和 Sr2+ 离子表现出很强的选择性，其形成常数比研究中其他离子的形成常数高约 103 倍。