title: Diphenylphosphine-Oxide-Fused and Diphenylphosphine-Fused Porphyrins: Synthesis, Tunable Electronic Properties, and Formation of Cofacial Dimers.
abstract: Diphenylphosphine-oxide-fused NiIIporphyrin 8 was synthesized from 3,5,7-trichloroporphyrin 5 via a reaction sequence of nucleophilic aromatic substitution with lithium diphenylphosphide, oxidation with H2O2, and palladium-catalyzed intramolecular cyclization. Reduction of 8 with HSiCl3gave diphenylphosphine-fused NiIIporphyrin 9. The embedded P=O and P moieties serve as a strong electron-accepting and electron-donating group to perturb the optical and electrochemical properties of the NiIIporphyrin. NiIIporphyrin 9 is diamagnetic with a low-spin NiIIcenter in solution but becomes paramagnetic with a five-coordinated NiIIcenter with high-spin (S=1) state in the solid state. Diphenylphosphine-oxide-fused ZnIIporphyrin 10 was also synthesized and shown to form a face-to-face dimer with mutual O-Zn bonds in the crystal and in nonpolar and moderately polar solvents. The dimerization of 10 in CDCl3has been revealed to be an entropy-driven process with a large entropy gain (ΔSD=207 J K-1mol-1).
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kasuga
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Norihito
authors.initials: N
authors.lastname: Fukui
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Atsuhiro
authors.identifier: http://orcid.org/0000-0001-8697-8488
authors.initials: A
authors.lastname: Osuka
keywords: aggregation; entropy-driven dimerization; high-spin nickel; phosphorus; porphyrin