The Synthesis and Properties of Free‐Base [14]Triphyrin(2.1.1) Compounds and the Formation of Subporphyrinoid Metal Complexes

Abstract

The synthesis of [14]triphyrin(2.1.1) compounds is described. In contrast with conventional subporphyrins, which consistently contain a central boron atom, free-base heteroaromatic compounds can be formed. A modified Lindsey method was used to prepare a range of different [14]triphyrins(2.1.1) in yields of up to 35% based on the reaction of diethylpyrrole (1a) and fused pyrroles of bicyclo[2.2.2]octadiene (BCOD) (2a-e) and dihydroethanonaphthalene (4a) with various aryl aldehydes. The concentration of BF(3)·OEt(2) catalyst plays the key role in determining the yield of the [14]triphyrin(2.1.1) macrocycle relative to the conventional tetrapyrrole porphyrin product. Retro-Diels-Alder reactions of 2a-e and 4a result in the formation of [14]tribenzotriphyrin (2.1.1) (3a-e) and [14]trinaphthotriphyrin(2.1.1) (5a). The effects of exocyclic ring annulation on the electronic structure are examined in detail based on optical spectroscopy, theoretical calculations, and electrochemical measurements. The availability of free-base compounds enables the formation of [Re(I)(CO)(3)(triphyrin)] (6a) and [Ru(II)(CO)(2)Cl(triphyrin)] (7a) complexes based on a modified retro-Diels-Alder reaction. X-ray structures are reported for 4a and 6a.

Structure Modification and Spectroscopic Properties of Artificial Porphyrinoids

“…The peripheral moieties fused to the β‐carbon atoms of the pyrroles affected the electronic and optical properties of triphyrins more strongly than did changes in the meso aryl substituents. Triphyrin 14 with three peripheral dihydroethanonaphthalene pyrroles showed a B‐like band at 373 nm, which was similar to that of 11 and 13 (λ max= 379 nm in CH 2 Cl 2 ), and broad and weak Q‐like bands 22. [14]tri‐naphtho‐triphyrin(2.1.1) 15 was obtained quantitatively based on a retro Diels‐Alder reaction and exhibited a sharp and red‐shifted B band (447 nm) and a relatively intense Q band (Scheme ; Figure 3).…”

“…A further comprehensive study on the synthesis of [14]triphyrin(2.1.1) compounds revealed that the concentration of the BF 3 ⋅Et 2 O catalyst played a crucial role in determining the yield of the [14]triphyrin(2.1.1) macrocycle relative to the conventional tetrapyrrole porphyrin 22. During the Lindsey condensation of BCOD‐fused pyrrole and benzaldehyde, when 0.4 equivalent of BF 3 ⋅Et 2 O was used, the major product was found to be the tetraarylporphyrin.…”

“…They are 20–34 nm blue‐shifted relative to those of meso aryl‐substituted [14]tiphyrin(2.1.1) 11 16. Upon coordination with low valent metal ions, such as Re(I) and Ru(I) for 15 and Mn(I) and Re(I) for 19 , the original near‐planar triphyrin ligands adopted domed or bowl‐shaped conformations with metal ions located above the plane determined by the three inner nitrogen atoms (Scheme ) 22–23. These metal complexes showed blue‐shifted and less intense absorption bands relative to metal‐free triphyrins.…”

Synthesis of [14]Oxatriphyrins(2.1.1) and Their Transformation into Ethane‐Bridged Oxatripyrrins by Boron Complexation

“…[6,7] Commonly, triphyrins are known as subphthalocyanines and subporphyrins. Thus, [14]triphyrins(2.1.1) are available as monoanionic ligands and can be converted into diverse metal complexes, [8][9][10][11][12][13][14][15][16][17] as distinct from subphthalo cyanines and subporphyrins. We and others have developed the chemistry of [14]triphyrin(2.1.1), which has a relatively planar structure with 14π-electron aromaticity and can be isolated as a free base.…”

Interaction of Fe3+meso-tetrakis (2,6-dichloro-3-sulfonatophenyl) porphyrin with cationic bilayers: magnetic switching of the porphyrin and magnetic induction at the interface

“…The molecular interactions responsible for the stability of supramolecular structures are weak forces and consequently they require calculations with a high level of chemical accuracy [29][30][31][32][33]. Considering that single reference Hartree-Fock wave function theory (WFT) quantum mechanics and local density approximation (LDA) and even the generalized gradient approximation (GGA) KS-DFT do not have the accuracy required for the calculation of weak van der Waals-dispersion interactions/forces, both WFT and KS-DFT needed to be extended and even reformulated to be applied for the dispersion forces and interactions that are responsible for the stability of the noble gas dimers and stacked aromatics compounds.…”