title: meso-Aryl phenanthroporphyrins: synthesis and spectroscopic properties.
abstract: The successful synthesis of tetraphenyltetraphenanthroporphyrin (TPTPhenP; 5a) in 2006 under modified Rothemund-Lindsey conditions yielded a tetraphenyl porphyrinoid with a B band redshifted to an unprecedented 576 nm. Radially symmetric fused-ring expansion of tetraphenylporphyrin with phenanthrene moieties results in very deep saddling due to steric crowding and very marked redshifts of the Q and B (or Soret) porphyrinoid absorption bands. The extent to which the TPTPhenP structure can be further modified is explored, and the optical properties of TPTPhenPs are analyzed based on a perimeter model approach that makes use of time-dependent DFT calculations and magnetic circular dichroism spectroscopy and also based on a detailed analysis of the fluorescence emission. Attempts to introduce substituents at the ortho and meta positions of the meso-phenyl groups and to insert a central metal proved unsuccessful. The synthesis of a series of TPTPhenPs with strong electron-withdrawing (-CN, -NO(2)) and -donating (-CH(3), -N(CH(3))(2)) substituents at the para positions of the meso-phenyl rings is reported. Marked redshifts of the main spectral bands were consistently observed. The most pronounced spectral changes were observed with -N(CH(3))(2) groups (5i) due to a marked destabilization of the HOMO, which has large MO coefficients on the meso-carbon atoms. Protonation of 5i at both the ligand core and at the -N(CH(3))(2) groups resulted in unprecedented Q(00) band absorption at wavelengths greater than 1200 nm.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Xu
authors.forename: John
authors.initials: J
authors.lastname: Mack
authors.forename: Ana B
authors.initials: AB
authors.lastname: Descalzo
authors.forename: Zhen
authors.initials: Z
authors.lastname: Shen
authors.forename: Nagao
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Xiao-Zeng
authors.initials: XZ
authors.lastname: You
authors.forename: Knut
authors.initials: K
authors.lastname: Rurack
mesh_terms: D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D011166:Porphyrins; C409084:tetraphenylporphyrin