New ICT probes: synthesis and photophysical studies of N-phenylaza-15-crown-5 aryl/heteroaryl oxadiazoles under acidic condition and in the presence of selected metal ions
作者:Sabir H. Mashraqui、Subramanian Sundaram、A.C. Bhasikuttan
DOI:10.1016/j.tet.2006.11.094
日期:2007.2
probes. Photophysical properties have been studied under acidic condition as well as in the presence of selected metal ions, Ca2+, Ba2+, Mg2+, Na+, K+, and Li+. The changes in the ICT character of the probes, following the addition of trifluoroacetic acid, were interpreted in terms of site and degree of protonations. Based on the cation affinity, the ICT bands in both UV–vis and emission spectra experienced
结合N -phenylaza-15-crown-5和芳基/杂芳基恶二唑的分子探针6和7已被设计用作新型分子内电荷转移(ICT)探针。在酸性条件下以及在选定的金属离子,Ca 2 +,Ba 2 +,Mg 2 +,Na +,K +和Li +的存在下,已经研究了光物理性质。。加入三氟乙酸后,探针的ICT特性发生了变化,这是根据位点和质子化程度来解释的。基于阳离子亲和力,由于从共轭物中除去了氮杂冠醚氮,因此在紫外可见光谱和发射光谱中的ICT谱带都经历了不同程度的蓝移。阳离子诱导的光谱位移和稳定性常数显示了按Ca 2+ > Ba 2+ ≫Li + > Na + > K + > Mg 2+的顺序的结合强度。在离子矩阵中进行的竞争性实验还表明6和7与Ca 2+的相互作用更好。在金属离子的存在下,激发态衰变曲线基本上不受干扰。研究的探针显示出正溶剂溶剂变色,斯托克斯位移和激发态寿命随着溶剂极性的增加而增加。