【摘要】 2,6-二氨基吡啶(DAPD)衍生物都有较强的荧光。除DMHND(2,4-二甲基-7-羟-基1,8-萘啶)外,2,4-二甲基-7-胺基-1,8-萘啶(DMAND)和2,4-二甲基-7-丙烯酰胺基-1,8-萘啶(DMAAN)在加入过渡金属离子后,荧光强度增强,发射光谱红移,可以作为过渡金属离子的荧光探针。根据Irving-Williams顺序,以过渡金属中络合能力较强的Cu2+为代表,求算了DMAND和DMAAN与Cu2+的结合比,通过非线性拟合计算了结合常数,比较了它们与金属离子结合的强弱,DMAND较DMAAN为更灵敏的过渡金属离子荧光探针。更多还原

【Abstract】 Three derivatives of 2,6-diaminopyridine were synthesized with naphthyridine ring and —NH2,—OH and —NHCOCHCH2 groups.They are 2,4-dimethyl-7-hydroxyl-1,8-naphthyridine(DMHND),2,4-Dimethyl-7-amino-1,8-naphthyridine(DMAND) and DMAAN.The binding ability of the derivatives of 2,6-diaminopyridine for metal ions in acetonitrile was investigated using UV-Vis and fluorescence spectrometry.The changes of the dyes spectra were observed in the presence of transition metal ions,but were not observed in the presence of K+,Na+,Mg2+,Ca2+ and Pd2+.Except for DMHND that has weak binding ability for Cu2+,two dyes can bind with Cu2+ at the ratios of DMAAN∶Cu2+=1∶1,DMAND∶Cu2+=1∶1.The resulting binding curves were analyzed by nonlinear regression methods,giving the association constant for DMAAN to be about 4.4×105 L·mol-1,and about 6.3×106 L·mol1 for DMAND.DMAND contains an electron-donating group(amino group) conjugated to an electron-withdrawing group(the pyridine ring),and undergoes intramolecular charge transfer from the donor to the acceptor upon excitation by light.When Cu2+ interacting with the N of the pyridine ring enhances the electron-withdrawing character of this group,the spectrum is thus red-shifted and the intensity is increased.DMAND displayed a high sensitivity among the three derivatives of 2,6-diaminopyridine as the fluorescence probe of transition metal ions.更多还原