Structure, electronic states, and anion-binding properties of cyclo[4]naphthobipyrroles.
Three octaalkyl-substituted cyclo[4]naphthobipyrroles, studied in solution in the form of their sulfates, reveal absorption and magnetic circular dichroism (MCD) spectra very similar to those of the parent cyclo[8]pyrrole. A unique feature of these systems is a strong absorption in the near IR region. The analysis of MCD patterns based on a perimeter model reveals a hard-chromophore character of cyclo[4]naphthobipyrroles, i.e., ΔHOMO ≪ ΔLUMO. Comparison of Raman spectra obtained for crystalline samples and solutions, combined with the analysis of absorption and MCD spectra based on quantum chemical calculations reveals that cyclo[4]naphthobipyrroles exist in solutions as undissociated sulfates of the doubly protonated forms.
Institute of Physical Chemistry, Polish Academy of Sciences , Warsaw 01-224, Poland.
Patrycja
P
Kowalska
Sylwester
S
Gawinkowski
Tridib
T
Sarma
Pradeepta K
PK
Panda
Jacek
J
Waluk