Modular Synthesis of Benzene-Centered Porphyrin Trimers and a Dendritic Porphyrin Hexamer

Abstract

Rigid, star-shaped D 3-symmetric arrays have been synthesized in which three porphyrin macrocycles are attached to the 1, 3, and 5 positions each of a benzene core through linkers consisting of collinear repetitive phenylethynyl units. Using the same methodology, a dendridic porphyrin hexamer having an external diameter of ca. 10 nm has been also obtained. By successive substitution of the three benzene positions, both a porphyrin trimer, the three linkers of which are of different length, and a starlike porphyrin, in which the complexed metal ions are different from each other, have been synthesized. The latter is the first example of a prochiral arrangement of metal ions in a D 3-symmetric ligand. To investigate their capability of forming ordered self-assembled monolayers on gold substrates, some of the porphyrin trimers and the dendritic porphyrin hexamer described in this work bear meta-thioanisole units at the apical positions. Analogously to similar multiporphyrin systems described in the literature, in which, however, the chromophores were arranged collinearly, the interaction between the chromophores of the multiporphyrin arrays described in this work is negligible, in the ground state, while effective energy transfer takes place in the singlet excited state.

Synthesis of Phenylacetylene Dendrimers Having Sterically Congested Diazo Units and Characterization of Their Photoproducts

“…2-(3,5-Diiodophenyl)-1-(trimethylsilyl)acetylene (4) [16] was selected for the convergent synthesis. This monomer is easily prepared [16] in good yield from 1,3,5-triiodobenzene.…”

Synthesis of a Human Urate Transporter-1 Inhibitor, an Arginine Vasopressin Antagonist, and a 17β-Hydroxysteroid Dehydrogenase Type-3 Inhibitor, Using Ring-Expansion of Cyclic Ketoximes with DIBALH

“…Sonogashira coupling of methyl 3-bromo-6-iodobenzoate 17 and trimethylsilylacetylene followed by basic removal of the trimethylsilyl (TMS) group gave arylacetylene 18. The second Sonogashira coupling with iodobenzene or 3-iodo-1-methylthiobenzene 14,15) provided 1,2-diarylacetylenes 19. While hydrogenation of 19a smoothly gave ester 20a with catalytic platinum oxide under atmospheric pressure, reduction of 19b required high-pressure (70 atm) conditions for the high-yielding process.…”

Meso-Linked Multiporphyrins as Model for Light Harvesting Systems: Review

“…In the covalently linked porphyrin arrays, a variety of linkages such as ethyne [36,37], polyyne [38][39][40], ethylene [41], alkane [42,43] and aromatic entities [44][45][46] have been used to bridge the individual porphyrins. Lindsey et al have reported the synthesis of numerous phenylene-and diphenyl ethynyl-bridged multiporphyrins for mimicking the biological light-harvesting antenna systems and their photo physical properties have been studied [46][47][48].…”