Coordination features of difunctionalized B-cyclodextrins with carnosine: ESI-MS and spectroscopic investigations on 6A,6D-di-(B-alanyl-L-histidine)-6A,6D-dideoxy-B-cyclodextrin and 6A,6C-di-(B-alanyl-L-histidine)-6A,6C-dideoxy-B-cyclodextrin and their co

The synthesis and characterization of two ß-cyclodextrins (ß-CD) functionalized with two units of carnosine (ß-alanyl-l-histidine) through the amino group, 6A,6C-(ß-alanyl-L-histidine)-6A,6C-dideoxy-ß-cyclodextrin (ACCDAH) and 6A,6D-(ß-alanyl-L-histidine)-6A,6D-dideoxy-ß-cyclodextrin (ADCDAH), are reported. NMR and C.D. data of the ligands indicate a different interaction of dipeptide chains with upper rim and cavity of ß-CD. Analogously, spectroscopic and electrospray ionization mass spectrometry data show different copper(II) complex species formed by the two regioisomers. The ability of carnosine-cyclodextrin derivs. to bind copper ions in a head-to-tail fashion induces the formation of oligomeric species (up to hexamers) in the case of ACCDAH, where the two carnosine moieties are adjacent, while in the ADCDAH case the mutual interaction between the peptidic chains of two ADCDAH mols. allows the almost exclusive formation of a copper-assisted self-assembled dimeric species.