cpl isomannide isosorbideCongratulations to our Ph.D. student Valerio Zullo for the publication of the paper: "Tunable excimer circularly polarized luminescence in isohexide derivatives from renewable resources". In this study, in collaboration with Prof. Anna Iuliano, Prof. Gennaro Pescitelli, and Ph.D. Francesco Zinna, the authors showed the synthesis and chiroptical properties of pyrene and perylene derivatives of inexpensive chiral scaffolds: isomannide and isosorbide. Low-intensity ECD spectra were obtained, suggesting the absence of chromophore interaction in the ground state, except in the case of isomannide bis-perylenecarboxylate, whose ECD spectrum showed a positive exciton couplet.

All isomannide derivatives, with the only exception of the one containing a pyrenecarboxylate and a perylenecarboxylate, exhibited excimer CPL spectra, whereas isosorbide derivatives did not show any CPL. Isomannide derivatives bearing two pyrenecarboxylate or two pyrenylacetate groups showed positive CPL emission with dissymmetry factors up to 10 -2 , which depends on the conformational freedom of the appended units. The CPL sign, Stokes shift and order of magnitude of dissymmetry factor were reproduced by excited-state calculations on a representative compound. Interestingly, the mixed derivative containing pyrenic units with different spacing from the isomannide scaffold showed an oppositely signed excimer band with respect to the homo-substituted derivatives.
The work has been just accepted and it can be found at https://doi.org/10.1002/chem.202104226