title: Synthesis of phosphorescent asymmetrically π-extended porphyrins for two-photon applications.
abstract: Significant effort has been directed in recent years toward porphyrins with enhanced two-photon absorption (2PA). However, the properties of their triplet states, which are central to many applications, have rarely been examined in parallel. Here we report the synthesis of asymmetrically π-extended platinum(II) and palladium(II) porphyrins, whose 2PA into single-photon-absorbing states is enhanced as a result of the broken center-of-inversion symmetry and whose triplet states can be monitored by room-temperature phosphorescence. 5,15-Diaryl-syn-dibenzoporphyrins (DBPs) and syn-dinaphthoporphyrins (DNPs) were synthesized by [2 + 2] condensation of the corresponding dipyrromethanes and subsequent oxidative aromatization. Butoxycarbonyl groups on the meso-aryl rings render these porphyrins well-soluble in a range of organic solvents, while 5,15-meso-aryl substitution causes minimal nonplanar distortion of the macrocycle, ensuring high triplet emissivity. A syn-DBP bearing four alkoxycarbonyl groups in the benzo rings and possessing a large static dipole moment was also synthesized. Photophysical properties (2PA brightness and phosphorescence quantum yields and lifetimes) of the new porphyrins were measured, and their ground-state structures were determined by DFT calculations and/or X-ray analysis. The developed synthetic methods should facilitate the construction of π-extended porphyrins for applications requiring high two-photon triplet action cross sections.
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Esipova
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Vinogradov
mesh_terms: D018360:Crystallography, X-Ray; D008163:Luminescent Measurements; D008665:Metalloporphyrins / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D055668:Photochemical Processes; D017785:Photons; D010984:Platinum / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D008665:Metalloporphyrins; D011166:Porphyrins; D011725:Pyridines; D010984:Platinum; D010165:Palladium