title: Spectroscopy and Tautomerization Studies of Porphycenes.
abstract: Tautomerization in porphycenes, constitutional isomers of porphyrins, is strongly entangled with spectral and photophysical parameters. The intramolecular double hydrogen transfer occurring in the ground and electronically excited states leads to uncommon spectroscopic characteristics, such as depolarized emission, viscosity-dependent radiationless depopulation, and vibrational-mode-specific tunneling splittings. This review starts with documentation of the electronic spectra of porphycenes: Absorption and magnetic circular dichroism are discussed, together with their analysis based on the perimeter model. Next, photophysical characteristics are presented, setting the stage for the final part, which discusses the developments in research on tautomerism. Porphycenes have been studied in different experimental regimes: molecules in condensed phases, isolated in supersonic jets and helium nanodroplets, and, recently also on the level of single molecules investigated by optical and scanning probe microscopies. Because of the rich and detailed information obtained from these diverse investigations, porphycenes emerge as very good models for studying the complex, multidimensional phenomena involved in the process of intramolecular double hydrogen transfer.
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences , 01-224 Warsaw, Kasprzaka 44/52, Poland.|Faculty of Mathematics and Science, Cardinal Stefan Wyszyński University , Dewajtis 5, 01-815 Warsaw, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Waluk
mesh_terms: D002942:Circular Dichroism; D011166:Porphyrins / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D013237:Stereoisomerism
chemical_list: D011166:Porphyrins; C051407:porphycene