Motoki Toganoh

Blooming of confused porphyrinoids--fusion, expansion, contraction, and more confusion.

This article introduces an overview of progressively developing chemistry of N-confused porphyrin and related macrocycles. Study on confusion results in discovery of fusion and combination with expansion or contraction has provided uniquely important classes of porphyrinoids. Syntheses, properties and coordination chemistry of such porphyrinoids are briefly described. Possibilities in applications are also mentioned.

Synthesis, reactivity, and properties of N-fused porphyrin rhenium(I) tricarbonyl complexes

The reactions of N-fused tetraphenylporphyrin (NFTPP, 1a) and its 21-substituted derivatives, 21-Br-NFTPP (1b), 21-NO(2)-NFTPP (1c), and 21-Bz-NFTPP (1d), with Mn(CO)(5)Br gave the manganese(I) tricarbonyl complexes bearing N-fused tetraphenylporphyrinato ligands (2a-d), respectively, in 46-99% yields. The complexes were characterized by mass, IR, (1)H and (13)C NMR spectroscopy, and the final structural proof was evident from the X-ray crystallographic analysis for 2a. The crystals of 2a·CH(2)Cl(2) belong to the monoclinic space group P2(1)/n (#14), with a = 15.007(2) Å, b = 12.5455(19) Å, c = 21.150(3) Å, β = 102.227(4)°, and Z = 4. The lengths (Å) of three manganese-nitrogen and three manganese-carbon bonds are inequivalent respectively [Mn-N(2), 2.007(2); Mn-N(23), 2.033(2); Mn-N(24), 1.988(3); and Mn-CO, 1.798(4), 1.804(4), 1.841(3)], reflecting the asymmetric structure of the NFp ligand. The aromatic substitution reactions of 2a, such as nitration, formylation, and chlorination, proceeded without a loss of center metal to give the corresponding 21-nitro (2c), 21-formyl (2e), and 21-chloro (2f) derivatives, regioselectively. In the electrochemical measurements of 2, one reversible oxidation and two reversible reduction waves were observed. The redox potentials of 2 indicate the narrow energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) being consistent with the electronic absorption spectra that display the absorption edges over 1000 nm. Protonation occurred at the inner core nitrogen of 2a upon the addition of acids, which is inferred from the (1)H NMR spectra as well as theoretical calculations. By a treatment with amine N-oxides, demetalation of 2 proceeded to afford the corresponding NFP free-bases (1).

Synthesis and photophysical properties of N-fused tetraphenylporphyrin derivatives: near-infrared organic dye of [18]annulenic compounds.

A variety of N-fused porphyrin derivatives were prepared and their photophysical properties were investigated. Although intact N-fused tetraarylporphyrins showed almost no emission, introduction of electron-withdrawing groups such as a nitro group and a cyano group on the macrocycles caused significant refinements in their emission efficiency. Long emission wavelengths (900-1000 nm) as well as fairly large Stokes shifts (∼1200 cm(-1)) are exceptionally unique photophysical properties among [18]annulenic compounds, which could be rationalized by the excited state intramolecular proton transfer (ESIPT) process. Relatively weak emission quantum yields (∼5.0 × 10(-4)) and unusually short S(1) state lifetimes (∼13.5 ps) are in good agreement with the ESIPT process. The solvent and substituent effects on the photophysical properties are also discussed in conjunction with the theoretical studies, where the mesityl groups at the meso-positions play a unique role.

Endocyclic extension of porphyrin π-system in etheno-bridged N-confused tetraphenylporphyrin

Etheno-bridged N-confused tetraphenylporphyrin was synthesized through flipping of the confused pyrrole ring and endocyclic extension of [18]annulenic pi-conjugated system was exemplified by the absorption spectra as well as the calculated Kohn-Sham orbitals.

C-fused norrole: a fused corrole isomer bearing a N,C-linked bipyrrole unit.

Oxidative cyclization of a doubly N-confused bilane afforded a N-confused N,C-linked corrole (N-confused norrole), which was readily oxidized to form a C-fused N,C-linked corrole (C-fused norrole).

Singly N-confused [26]hexaphyrin: A binucleating porphyrinoid ligand for mixed metals in different oxidation states

Thus, forcoordination of two different metal ions in variable oxidationstates, an unsymmetrical binucleating environment would benecessary in the macrocycles. This environment could beattained by incorporating one confused pyrrole unit into thehexaphyrin system, namely a singly N-confused hexaphyrin(N

N-Heterocyclic Carbene Embedded in an N-Confused Porphyrin Framework

A rhenium(I) complex of an N-heterocyclic carbene ligand embedded in an N-confused porphyrin core was serendipitously synthesized by the reaction of an inner-methylated N-confused porphyrin with Re(2)(CO)(10).

Endocyclic Extension of Porphyrin π-System by Interior Functionalization of N-Confused Porphyrins

Internally alkynylated or cyanated N-confused porphyrins have been prepared, and these have been characterized by NMR, UV/Vis/NIR absorption, and X-ray analysis. The desired porphyrins have been synthesized by interconversion between an N-confused porphyrin and an N-fused porphyrin. In the case of terminal alkyne derivatives, intramolecular addition of a pyrrolic NH moiety to the triple bond occurred at ambient temperature to give etheno-bridged N-confused porphyrins. Significant bathochromic shifts in the absorbances of these compounds may be reasonably explained in terms of an increase in their HOMO energy levels due to effective overlap of the porphyrin pi-orbital and the bridged alkene pi-orbital. The corresponding rhodium(I) complexes have also been prepared, and these have been characterized by NMR and X-ray analysis.

Synthesis and catalytic activity of rhodium diene complexes bearing indenyl-type fullerene η5-ligand

Abstract Rhodium η 5 -complexes bearing an indenyl-type fullerene ligand, Rh[C 60 (PhCH 2 ) 2 Ph](cod) ( 2 ), Rh[C 60 (PhCH 2 ) 2 Ph](nbd) ( 3 ) and Rh(C 70 Ph 3 )(cod) ( 4 ), have been synthesized from the corresponding fullerene tri-adducts in 93–96% yields. X-ray crystallographic analysis of 4 indicated that the structure of 4 is similar to that of Rh(Ind)(cod). The rhodium complex 2 catalyzes alkyne trimerization reactions and hydroboration reactions.

Comparative spectroscopic studies on porphyrin derivatives: electronic perturbation of N-confused and N-fused porphyrins

N-confused and N-fused porphyrins revealed quite unique photophysical properties arising from their perturbed pi-conjugation pathways induced by structural modifications such as confusion and fusion of pyrrole rings compared with their parent porphyrin molecules.