Efficient Synthesis of Light-Harvesting Arrays Composed of Eight Porphyrins and One Phthalocyanine

Abstract

Effective light-harvesting arrays require multiple photoactive energy donors that funnel energy to an energy acceptor. Porphyrins and phthalocyanines are attractive components for light-harvesting arrays due to their strong absorption in the blue and red regions, respectively, and because energy transfer can occur from porphyrin to phthalocyanine regardless of their respective metalation states. Star-shaped light-harvesting arrays comprised of eight peripheral porphyrins and one core phthalocyanine have been prepared by a streamlined synthesis involving minimal reliance on protecting groups, a high degree of convergence, and facile chromatographic purification. The synthesis involves three distinct stages of complementary chemistries (porphyrin formation, Pdmediated porphyrin dimer formation, phthalocyanine formation). Statistical reaction of piodobenzaldehyde, a phthalonitrile-linked benzaldehyde, and 5-mesityldipyrromethane afforded the desired trans-iodo/phthalonitrile-substituted porphyrin, which underwent Pd-mediated coupling with a monoethynyl porphyrin to give the porphyrin dimer bearing a phthalonitrile unit. Reaction of the dimer in 1-pentanol in the presence of MgCl 2 and DBU for 48 h at 145 °C afforded the allmagnesium (porphyrin) 8 -phthalocyanine nonamer (MgP) 8 MgPc in 5.0% yield. The same reaction with lithium pentoxide in 1-pentanol for 2 h at 145 °C gave the all-free base nonamer (H 2 P) 8 H 2 Pc in 34% yield. The all-zinc nonamer (ZnP) 8 ZnPc was prepared by addition of zinc acetate at the end of the reaction. Similar treatment of a monomeric porphyrin-phthalonitrile afforded the pentameric (ZnP) 4 ZnPc in 58% yield. The (MgP) 8 MgPc was also obtained by magnesium insertion of (H 2 P) 8 H 2 -Pc. The three nonamers were readily purified and are soluble in solvents such as toluene, THF, and CH 2 Cl 2 . Each nonamer absorbs strongly across the solar spectrum and exhibits efficient energy transfer from the porphyrins to the phthalocyanine.

Excited‐State Deactivation of Branched Phthalocyanine Compounds

“…The two hydrogen atoms in the center of the macrocycle can be replaced by various metal atoms. [1,[24][25][26][27] Pcs can also be covalently or noncovalently linked to other chromophores,s uch as fullerene, [28][29][30][31] perylenediimide, [12,32,33] carotene, [34][35][36] or porphyrins [37,38] to build supermolecular systems that used as new ecological materials, especially as donor-acceptor systemst oa ccomplish energy and/or electron migration. Thus, their original physical parameters and chemical character,such as their solubility,a ggregation status, extinction…”

Synthesis, Characterization and Self-Assembly Properties of a New Copper-Phthalocyanine Core Acrylate Block Copolymer

“…The first attempt to synthesize CuPc was by refluxing 1 in 2-(dimethylamino)ethanol in the presence of copper acetate under an argon atmosphere, but no characteristic green color of Pc was obtained, even after 3 days. Next, we tried to synthesize the CuPc via its Li2Pc [35]. After purification, the desired CuPc was obtained, but in very low yield (12%).…”

Synthesis and third-order nonlinear optical properties of novel ethynyl-linked heteropentamer composed of four porphyrins and one pyrene

“…Effective and simple synthetic pathway to alkyne-linked porphyrin arrays with well-defi ned arrangement has attracted great attention for many researchers [16][17][18][19][20][21][22][23]. In this paper, we have designed and synthesized novel multi-porphyrins-pyrene arrays 1 and 2 with a star arrangement (Scheme 1), in which four meso-tetraphenyl porphyrins are linked to the center unit of pyrene by four acetylenyl bonds.…”