Synthesis of Crown Ether Metal-prophyrin and Its Anion Recognition

A benzo-15-crown-5 modified 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin(1) was synthesized and used for binding with Hg2 +ion to form crown ether metal-prophyrin complex(3). UV-Vis and1 H NMR were used to investigate the formation and self-assembly of complex 3. The difference of1 H NMR spectra of complexes 3 and 2 reveals that a synergy effect of prophyrin and crown ether exists. The anion recognition and mechanism of complex 3 were also studied. After addition of Na NH2,an obvious red shift in the UV-Vis spectra was observed accompanied with a color change from green to chartreuse viewed by naked eye. At the same time,the chemical shift of —CH2— in crown ether ring shifted from 3. 12 to 3. 16 and 3. 32 to 3. 34,respectively. This phenomenon can be explained by the strong nucleophilic property of amino anion.However,addition of other sodium salts such as Na Cl,Na H2PO4 and Na HCO3 could not result in the same phenomenon. This study provides a method for visible anion recognition.