Orientation effects on excited state dynamics of zinc porphyrin–free base porphyrin–pyromellitimide triads

✍ Scribed by Atsuhiro Osuka; Ji-Young Shin; Ryusho Yoneshima; Hideo Shiratori; Takeshi Ohno; Koichi Nozaki; Yoshinobu Nishimura; Iwao Yamazaki; Seiji Taniguchi; Takenori Shimizu; Tadashi Okada

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 151 KB
• Volume: 03
• Category: Article
• ISSN: 1088-4246
• DOI: 10.1002/(sici)1099-1409(199912)3:8<729::aid-jpp162>3.0.co;2-f

✦ Synopsis

The synthesis is described of fixed distance triads consisting of zinc porphyrin (ZP), metal-free porphyrin (HP) and pyromellitimide (I) in which the ZP and HP moieties are bridged by a rigid 4,4'biphenylene spacer and related spacers, being held with dihedral angles defined by the torsional angle () of the 4,4'-biphenylene spacer varying from nearly coplanar ( = 0°, phenanthrene spacer) to nearly orthogonal ( = 90°, 2,2',6,6'-tetramethylbiphenylene spacer). Using these models, the effects of the dihedral angle of the two porphyrins have been examined for singlet-singlet excitation energy transfer from ZP to HP, hole transfer from HP to ZP and charge recombination of ZP -HP-I À to the ground state. In the three processes examined, the observed rate constants are roughly in the order of 1d (coplanar) !1c (nearly coplanar) b1a (tilted) b1b (orthogonal).