Masataka Umetani

Single- and double-helices of α,α′-dibenzylaminotripyrrin: solution and solid state studies† The dimeric association of α,α′-di(benzylamino)tripyrrin in chloroform was found to be 40 times less effective than that of previously reported α,α′-dianilinotripyrrin, which, however, led us to observe the co-crystal structure of single and double helix forms. Attachment of chiral phenylethylamines on the same tripyrrin platform was also performed to induce helical chirality.

5,20-Diheterohexaphyrins: metal-template-free synthesis and aromaticity switching As the first example of expanded heteroporphyrins with heteroatoms at meso-positions, 5,20-dithiahexaphyrins and 5,20-diazahexaphyrins were synthesized via nucleophilic substitution reactions of α,α’-dibromotripyrrin as the key step.

A new motif for artificial double helices was developed on the basis of α,α’-disubstituted tripyrrin. α,α’-Dibromotripyrrin 3 was prepared by a gentle bromination at the pyrrolic α-positions of 5,10-diphenyltripyrrane followed by oxidation with DDQ.