Different sensing modes of fluoride and acetate based on a calix[4]arene with 25,27-bistriazolylmethylpyrenylacetamides
作者:Hao-Chih Hung、Yung-Yu Chang、Liyang Luo、Chen-Hsiung Hung、Eric Wei-Guang Diau、Wen-Sheng Chung
DOI:10.1039/c3pp50175b
日期:2014.2
25,27-Bis1′- N-(1-pyrenyl)-aminocarbonylmethyl-1 H-[1′,2′,3′]tri-azolyl-4′-methoxy-26,28-dihydroxycalix[4]arene, 4, is synthesized as a fluorescent chemosensor for the selective detection of both anions and ion pairs in MeCN. Sensor 4 uses bis-triazoles as ligands to bind a metal ion, bis-amides and bis-triazoles as the sites to recognize anions, and pyrenes as fluorophores. Among eight anions screened, chemosensor 4 showed a marked fluorescence change toward F−, H2PO4− and AcO−, but 4 responded to each anion in a distinct way. In the presence of F− at low concentrations, the dynamic excimer emission of compound 4 at λmax 482 nm was quenched, but an emission at λmax 472 nm appeared at large doses of F−. A control compound 6 showed very similar red shifts in the UV-vis and excitation spectra as 4 did, and its 472 nm emission band grew as the fluoride doses increased. Thus, the growth of the 472 nm emission of 4 and 6 in the presence of excess F− may be because strong H-bonding interactions of amido protons with F− favoured the formation of pyrene dimers in the ground state with charge transfer characteristics. The addition of H2PO4−, unlike F−, to a solution of 4 showed an enhanced monomer emission but a decreased excimer emission (λmax 482 nm). Adding AcO− to 4 produced a systematic change from a dynamic excimer (λmax 482 nm) to λmax 472 nm but with very little change in the UV-vis spectrum. Time-resolved fluorescence measurements on compound 6 with F− and AcO− confirmed that the 472 nm emission band mainly came from static excimers for the former, but was partly from a dynamic excimer for the latter because it contained a growth component in the fluorescence decay traces. Without pre-treatment with an anion, chemosensor 4 showed recognition of only metal ions Cu2+, Hg2+ and Cr3+, but it became sensitive to Ag+ when it was pretreated with fluoride.
25,27-双1′-N-(1-芘基)-氨基甲酰基甲基-1H-[1′,2′,3′]三唑基-4′-甲氧基-26,28-二羟基杯芳烃,4,被合成为选择性检测MeCN中阴离子和离子对的荧光化学传感器。传感器4使用双三唑作为配体来结合金属离子,使用双酰胺和双三唑作为识别阴离子的位置,芘作为荧光基团。在筛选的八种阴离子中,化学传感器4对F−、H2PO4−和AcO−表现出显著的荧光变化,但4对每种阴离子的响应方式各不相同。在低浓度下,F−存在时化合物4在λmax 482 nm的动态外消旋发射被猝灭,但在高浓度F−下则出现λmax 472 nm的发射。一种对照化合物6在UV-vis和激发光谱上显示出与4非常相似的红移,其472 nm发射带随着氟离子剂量的增加而增强。因此,4和6在过量F−存在下472 nm发射的增强可能是由于氨基质子与F−之间强的氢键相互作用促进了基态下带有电荷转移特征的芘二聚体的形成。与F−不同,向4的溶液中加入H2PO4−显示增强的单体发射,但外消旋发射(λmax 482 nm)减弱。向4中加入AcO−产生了从动态外消旋(λmax 482 nm)到λmax 472 nm的系统性变化,但在UV-vis光谱中变化很小。对化合物6进行时间分辨荧光测量,发现472 nm的发射带主要来自于前者的静态外消旋,而后者则部分来自动态外消旋,因为在荧光衰减曲线中包含了生长成分。在未进行阴离子预处理的情况下,化学传感器4仅识别金属离子Cu2+、Hg2+和Cr3+,但在预处理氟离子后则对Ag+变得敏感。