N-confused Tetraphenylporphyrin Research Articles

Bis[iridium(I)] Complex of Inverted N-Confused Porphyrin

The reaction of N-confused tetraphenylporphyrin with IrCl(CO)2(p-toluidine) gave a novel bis[iridium(I)] complex, wherein the confused pyrrole ring took an inverted conformation.

Rhenium Complexes of N-Methyl N-Confused Tetraphenylporphyrin and Its Normal Isomer

Abstract The rhenium tricarbonyl complexes bearing tridentate porphyrin ligands, N-methyltatraphenylporphyrin and N-methyl N-confused tatraphenylporphyrin, were prepared and their structures were studied by X-ray crystallographic analysis. Drastic change of HOMO–LUMO gap by confusion of N-methylpyrrole moiety was illustrated from experimental and theoretical studies.

Synthesis and crystal structure of the first lanthanide complex of N-confused porphyrin with an η2agostic C–H interaction

The reaction of Ln[N(SiMe3)2]3.[LiCl(THF)3](x)(Ln = Yb and Er) with N-confused tetraphenylporphyrin (H2NCTPP) followed by Na(L(OMe))(L(OMe)=(eta5-C5H5)Co[P(=O)(OMe)2]) gives (NCTPP)Ln(L(OMe)), whose X-ray structures exhibit an eta2 agostic interaction between the metal centre and the inner C-H bond of the NCTPP ligand.

Spectroscopic and electrochemical characterization of solutions and films of a new redox couple: Co(II)/Co(III) N-confused porphyrin

Co(II) ion was introduced in N-confused tetraphenylporphyrin (NCTPP) as evidenced by ESR and UV–Vis spectroscopy as well as electrochemical methods. The Co(II)NCTPP complex shows a typical ESR spectrum of a high spin 3d 7 Co(II) ion, Soret bands at 460 and 445 nm in CH 2Cl 2 and CH 3CN, respectively, and oxidation potential of +0.55 V vs. Ag/AgCl/KCl (satd.). Adsorbed films of Co(II)NCTPP on glassy carbon electrodes are stable and show reversible redox waves in aqueous basic solutions attributed to the Co(II)/Co(III)NCTPP couple with E 1/2 = +0.025 V at pH 14. It is also shown that NCTPP can be electropolymerized and the films readily metallate with Co(II) ions.

One-step synthesis and characterization of difunctionalized N-confused tetraphenylporphyrins.

Three disubstituted N-confused porphyrins (2-4) were prepared in ca. 4% yield using a one-pot synthesis. These porphyrins bear 3,5-di-tert-butylphenyl groups substituted at the C(5) and C(20) meso positions and para-substituted (Br, NO(2), ethynyl) phenyl groups at the C(10) and C(15) meso positions. The specific orientation of the aryl rings around the macrocycle in porphyrin 2 was definitively determined using a combination of 1D ((1)H and (13)C) and 2D (gHMQC and gHMBC) NMR spectroscopy. The absorption spectra of 2-4 in CH(2)Cl(2) and dimethylacetamide are similar to those of N-confused tetraphenylporphyrin in the same solvents but have Soret and Q-bands that are shifted to lower energies. Steady-state fluorescence measurements revealed Q(x)(0,0) and Q(x)(0,1) bands similar in energy to the unsubstituted NCPs 1i and 1e. The fluorescence quantum yield results for two of these NCPs (2, 4) are atypical of porphyrin behavior and are being further investigated by time-resolved spectroscopy.

Modulation of axial coordination in N-confused porphyrin–antimony(v) dibromide complex by proton stimulus

The change of the axial bond length in the antimony(V) N-confused tetraphenylporphyrin dibromide complex was demonstrated by protonation and confirmed from X-ray single crystal analyses.

Dimeric and monomeric forms of manganese N-confused porphyrin.

The synthesis and structural characterization of a manganese adduct of N-confused tetraphenylporphyrin (NCTPP) is presented; in the absence of coordinating ligands this complex forms a novel dimer structure and demonstrates a potential manganese agostic interaction with the interior pyrrolic CH as seen in other first row transition metal NCTPP compounds.

Effects of diverse acid catalysts on the reaction course in the two-step one-flask synthesis of meso-tetraphenylporphyrin

A set of 45 acids or acid combinations was examined in the condensation of pyrrole + benzaldehyde (10 mM each in CH 2 Cl 2) leading to meso-tetraphenylporphyrin (TPP). Initial screening experiments identified suitable acid catalysts and the optimal concentration (in terms of TPP formation) for each acid. Subsequent experiments followed the time course of reactions using the best conditions identified in the screening experiments. The reaction course was followed by monitoring reactions from 1 min to 24 h for the yield of TPP (by UV-vis and HPLC), the yields of N-confused tetraphenylporphyrin and tetraphenylsapphyrin (by HPLC), the quantity of unreacted benzaldehyde (by TLC), and the oligomer composition (by laser desorption mass spectrometry). Diverse acids (Brønsted or Lewis; soluble or insoluble) were found to provide yields of TPP ranging up to ~50%. Only 10 acids gave no TPP. In addition, N-confused tetraphenylporphyrin was found to be a ubiquitous byproduct, whereas tetraphenylsapphyrin was not widely observed. MgBr 2-etherate and CuCl 2 each catalyzed porphyrinogen formation and resulted in porphyrin metalation following oxidation and neutralization of the reaction mixture, thereby providing direct, one-flask syntheses of magnesium and copper porphyrins. Observations concerning the reaction course obtained from prior studies of TFA or BF 3-etherate catalysis have been found to be quite general across a broad range of acid catalysts. Collectively, these results show that many acids have potential utility in porphyrin syntheses.

Regioselective oxidative liberation of aryl-substituted tripyrrinone metal complexes from N-confused porphyrin.

[reaction: see text] A Cu(II) complex of the first aryl-substituted tripyrrinone derivative, 14-benzoyl-5,10-diphenyl-1-oxo-tripyrrinato copper(II) (3-Cu) was obtained in the reaction of N-confused tetraphenylporphyrin (NCTPP) and Cu(OAc)(2) in refluxing toluene, and subsequent treatment with acid afforded a free tripyrrolic ligand that could bind a variety of transition metals.

A Survey of Acid Catalysts for Use in Two-Step, One-Flask Syntheses of Meso-Substituted Porphyrinic Macrocycles

[reaction: see text] Diverse Lewis acids and Bronsted acids were examined in the two-step, one-flask synthesis of meso-tetraphenylporphyrin, N-confused tetraphenylporphyrin, and tetraphenylsapphyrin. The scope of acid catalysis was found to be very broad, with 35 of 45 acids providing TPP in yields ranging from 5% to 58%. NC-TPP was also widely observed in yields of 1-40%, and TPS was infrequently observed in yields of <1%. Additionally, conditions were found for direct preparation of magnesium TPP and copper TPP.

An Efficient One-Flask Synthesis of N-Confused Tetraphenylporphyrin

[formula: see text] N-Confused meso-substituted porphyrin is a porphyrin isomer previously available from one-flask porphyrin syntheses as a low-yield byproduct (< 7.5%). We have found that methanesulfonic acid catalyzed condensation of pyrrole and benzaldehyde followed by DDQ oxidation provides N-confused tetraphenylporphyrin (NC-TPP) in up to 39% yield in analytical scale experiments. Preparative synthesis provided an isolated yield of 35% (800 mg). This represents a > 5-fold yield improvement and makes significant quantities of NC-TPP readily available.

N-Confused Tetraphenylporphyrin−Silver(III) Complex1

The synthesis, characterization, and X-ray structure of the first example of an air-stable silver(III) complex of an N-confused tetraphenylporphyrin (5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin argentate(III) or Ag(III)NCTPP, 7) is reported. Crystals of Ag(III)NCTPP·CH2Cl2 belong to the monoclinic space group P21/c (No. 14), with a = 9.038(4) A, b = 15.097(3) A, c = 25.578(8) A, β = 91.32(3)°, and Z = 4. The lengths (A) of the three silver−nitrogen and one silver−carbon bonds are inequivalent [Ag−N(1), 2.06(2); Ag−N(2), 2.08(2); Ag−N(3), 2.03(2); and Ag−C(17), 2.04(2)], reflecting the asymmetric structure of the NCTPP ligand. The very small distortion from a square planar geometry is shown in N−Ag−N and N−Ag−C angles (degrees): N(1)−Ag−N(2), 89.7(8); N(1)−Ag−N(3), 179(1); N(1)−Ag−C(17), 90.3(9); N(2)−Ag−N(3), 89.6(9); N(2)−Ag−C(17), 179(1); and N(3)−Ag−C(17), 90.9(1). The diamagnetic nature of Ag(III)NCTPP was confirmed by 1H and 13C NMR and magnetic susceptibility measurements. Electrochemical and sp...

N-Confused Tetraphenylporphyrin and Tetraphenylsapphyrin Formation in One-Flask Syntheses of Tetraphenylporphyrin.

The yields of tetraphenylporphyrin (TPP), N-confused tetraphenylporphyrin (NC-TPP), and tetraphenylsapphyrin (TPS) were examined under diverse conditions in the one-flask room-temperature reaction of pyrrole and benzaldehyde. The conditions examined included TFA and BF(3)-etherate catalysis, acid concentrations, pyrrole and benzaldehyde concentrations, pyrrole:benzaldehyde ratios, the addition of salt, and reaction times. The quantities of TPP, NC-TPP, and TPS were determined by HPLC. The yield of NC-TPP mirrored that of TPP during systematic variation of reaction parameters but was consistently lower (</=7.5%). The rate of NC-TPP formation also resembled that of TPP. Excess pyrrole was not required to form NC-TPP. About 2-fold more NC-TPP was obtained with BF(3)-etherate compared with TFA catalysis. TPS was observed in only a few of the reactions examined. The yield of TPS peaked early and declined well before the maximum yields of TPP and NC-TPP were reached. The highest yield of TPS observed was 1.2%. TPS was produced in higher yields by TFA compared with BF(3)-etherate catalysis. Additional pigments with chromatographic properties spanning the range of TPP and NC-TPP were observed in very low yield but were not characterized. N-confused tetramesitylporphyrin was isolated from the reaction of mesitaldehyde and pyrrole under BF(3)-ethanol cocatalysis. Examination of the Adler reaction of benzaldehyde and pyrrole revealed the presence of NC-TPP and TPS in the filtrate but not in the crystalline TPP material. The substantial chromatographic differences between the porphyrins and N-confused porphyrins make for straightforward isolation of the purified porphyrin devoid of contaminating N-confused porphyrin. These studies indicate that the scope of conditions yielding NC-TPP is extremely broad.

Nitration of N-Confused Porphyrin

Abstract The internal carbon of the inverted pyrrole in N-confused tetraphenylporphyrin 1 (5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin) was nitrated by using the following aqueous solutions at room temperature for several minutes; (1) NaNO2/HCl (yield 71%) and (2) 30 wt% nitric acid (yield 27%).

Specific binding of iodide ion to N-confused tetraphenylporphyrin (NC-TPP) at the air–water interface

Halide recognition by a porphyrin aggregate at the air-water interface has been studied. π-A Isotherms and UV reflection spectra of mixed monolayers of 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin, trivial name ‘N-confused tetraphenylporphyrin’(NC-TPP), with methyl octadecanoate were measured in 1 mmol dm–3 NaX aqueous solution (X = F, Cl, Br, I). π-A Isotherms of NC-TPP alone were extracted from those of the mixed monolayers at various mixing ratios. Among the anions investigated, only the I– containing subphase gave a more condensed π-A isotherm and a shifted UV reflection spectrum. The Soret band showed a red shift (465 nm) in NaI solution and blue shifts (425 nm) in pure water and in the other salt solutions, and these shifts were attributed to the occurrence of two different aggregation modes, J-like aggregate and H aggregates, respectively. X-Ray photoelectron spectroscopy (XPS) also demonstrated the incorporation of iodine but no other halogen atoms in the LB films. Loss of counterions (F–, Cl–, Br–) in concurrence with deprotonation during LB transfer apparently induced formation of the J-like aggregate of free-base NC-TPP in the transferred films. In contrast, iodide was kept in the film upon LB transfer, because the aggregation mode of NC-TPP remained unchanged. The important role of the modes of porphyrin aggregation in the anion recognition is discussed.