Four cone resorcarene octamethyl ethers (10, 11, ent-10, and ent-11) tetrafunctionalized at the feet with valyl-leucine [LL- (6); DD- (ent-6)] and leucyl-valine [LL- (9); DD- (ent-9)] methyl esters have been synthesized. These compounds, obtained by conjugation of macrocycle tetracarboxylic acid chlorides with the appropriate terminal amino groups of the above dipeptides, are N-linked peptidoresorcarenes. We found that these macrocycles (M) are capable of recognizing the homologue dipeptides as guests (G), both in solution and in the gas phase, by forming relatively stable host-guest complexes ([M•G]), resistant to chromatographic purification but not to heating. Complexation phenomena between M and G in solution were investigated by NMR methods, including NMR DOSY experiments, for the detection of translational diffusion. Heteroassociation constants of 2030 and 186 M-1 were obtained by the Foster-Fyfe method for the complexes [10•6] and [10•ent-6], respectively, the latter being comparable to the self-association constant of dipeptide itself. Conversely, the structural features of the proton-bound complexes [M•H•Gn]+ (n ) 1, 2), generated in the gas phase by electrospray ionization mass spectrometry (ESI-MS), were investigated by collision-induced dissociation (CID) experiments. In both cases, the four N-linked peptidoresorcarenes were shown to act as synthetic receptors and to recognize the homologue dipeptide by means of hydrogen bonds.
|Autori:||BOTTA B.; D'ACQUARICA I.; DELLE MONACHE G.; SUBISSATI D.; UCCELLO BARRETTA G.; MASTRINI M.; NAZZI S.; SPERANZA M.|
|Titolo:||Synthesis and Host-Guest Studies of Chiral Lower Rim N-linked Peptidoresorc4arenes|
|Anno del prodotto:||2007|
|Digital Object Identifier (DOI):||10.1021/jo7016636|
|Appare nelle tipologie:||1.1 Articolo in rivista|