Deducing the conformational space for an octa-proline helix.

A molecular dyad, PY-P-PER, comprising a proline octamer sandwiched between pyrene and perylene terminals has been synthesized in order to address the dynamics of electronic energy transfer (EET) along the oligo-proline chain. A simple pyrene-based control compound equipped with a bis-proline attachment serves as a reference for spectroscopic studies. The N-H NMR signal at the terminal pyrene allows distinction between and amides and, although the crystal structure for the control has the conformation, temperature-dependent NMR studies provide clear evidence for / isomerisation in D-DMSO.