Selective binding of glucose-6-phosphate, 3,4-dihydroxyphenylalanine (DOPA) and their analogs with a boronic-acid-appended metalloporphyrin

A zinc(II) porphyrin (2) bearing an intramolecular boronic acid was synthesized. It was shown on the basis of absorption spectroscopy. ³¹P NMR spectroscopy and circular dichroism (CD) spectroscopy that 2 can bind glucose-6-phosphate (G-6-P) in a two-point interaction manner, one between the 1,2-diol moiety and the boronic acid moiety and the other between the phosphate moiety and Zn(II). This system was successfully applied to facile discrimination of G-6-P from analogous glucose-1-phosphate, which is very difficult by other methods. It was also shown that 2 is applicable to the selective binding of 3,4-dihydroxyphenylalanine and its analogs. In this system the boronic acid moiety in 2 binds the catechol moiety in amino acids and Zn(II) binds the amino group. Thus, the present study demonstrates that combination of metalloporphyrins and boronic acids enables us to design very potential receptors for guests containing a diol group and a ligand group within a molecule.