Porphyrin Chemistry

A green and sustainable method for the oxidation of 1,3-dihydrobenzo[c] thiophenes to sulfones using metalloporphyrin complexes Two efficient methods are reported for the oxidation of 1,3-dihydrobenzo[c]thiophenes to sulfones in good to high yields using H 2 O 2 in the presence of catalytic amounts of porphyrin-based catalysts in ethanol or acetonitrile as solvents at room temperature. The presence of electron-donating or electron-withdrawing groups, in the benzene ring of 1,3-dihydrobenzo[c]thiophene, is well tolerated.

A simple route to tetraaryltetrabenzoporphyrins (Ar 4 TBPs) is developed; the procedure allows for the introduction of substituents on both benzo-and phenyl-rings and employs readily available, inexpensive components. † Electronic supplementary information (ESI) available: experimental data. See http://www.rsc.org/suppdata/cc/b0/b008816l/ Scheme 1 Reagents and conditions: a, DMM, py, 140 °C, pressure tube, 85%; b1, (i) PhSCl. CH 2 Cl 2 ; (ii) Et 3 N; (iii) Oxone, MOH, 86% for three steps; b2, (i) PhSCl, CH 2 Cl 2 ; (ii) MCPBA; (iii) DBU, 81% for three steps; c, CNCH 2 CO 2 t Bu, t BuOK, THF, Ar, 0 °C, 80-95%; d, TFA-CH 2 Cl 2 , Ar, rt, 35-40%; e, (i) YC 6 H 4 CHO, BF 3 ·Et 2 O, CH 2 Cl 2 ; (ii) DDQ, 25-35% for two steps; d + e, YC 6 H 4 CHO (X = H), AcOH, TosOH, CH 2 Cl 2 , 8-12%; f, (i) M(OAc) 2 , MeOH-CHCl 3 ; (ii) DDQ, THF or MeCN, reflux, M = Zn, Cu, Ni, 98% for two steps.

In this report, we describe an iron(III) complex containing a carbazole-based tridentate ligand that catalyzes highly enantioselective asymmetric epoxidation of (E)-alkenes at room temperature. The nonheme iron(III) complex has a five-coordinated trigonalbipyramidal structure, and its two-electron oxidized state has the similar electronic structure as that of iron porphyrins.

Second harmonic generation (SHG)-based probes are useful for nonlinear optical imaging of biological structures, such as the plasma membrane. Several amphiphilic porphyrin-based dyes with high SHG coefficients have been synthesized with different hydrophilic head groups, and their cellular targeting has been studied. The probes with cationic head groups localize better at the plasma membrane than the neutral probes with zwitterionic or non-charged ethylene glycol-based head groups. Porphyrin dyes with only dications as hydrophilic head groups localize inside HEK293T cells to give SHG, whereas tricationic dyes localize robustly at the plasma membrane of cells, including neurons, in vitro and ex vivo. The copper(II) complex of the tricationic dye with negligible fluorescence quantum yield works as an SHG-only dye. The free-base tricationic dye has been demonstrated for two-photon fluorescence and SHG-based multimodal imaging. This study demonstrates the importance of a balance between the hydrophobicity and hydrophilicity of amphiphilic dyes for effective plasma membrane localization.

Environmentally friendly and efficient synthesis of 2,5-furandicarboxylic acid (FDCA), a polyester building block chemical from biomass, was carried out in water by aerobic oxidation of 5-hydroxymethylfurfural (HMF) with highly cross-linked, robust structured, and thermally stable Fe III -porous organic polymer (Fe III -POP-1) material containing basic porphyrin subunits and iron metal center. EPR analysis confirmed that the catalyst retained the oxidation state of Fe(III) after catalysis and can be reused.

"Lanthanide (Yb3+, Nd3+) complexes equipped with red-absorbing hydroporphyrin (chlorin) antennae were synthesized and characterized. The syntheses are scalable, highly modular, and enable the introduction of different chlorins functionalized with a single reactive group (COOH or NH2).
Absorption maxima were dependent on chlorin substitution pattern (monomeso aryl or dimeso aryl) and metalation state (free base or zinc chelate). The complexes benefit from dual chlorin (610−639 nm) and lanthanide (980 or 1065 nm for Yb- or Nd-complexes, respectively) emission in the biologically relevant red and near IR region of the spectrum."

A homologous series of b-brominated Mn-porphyrins were prepared and their catalytic activities were investigated in the oxidation of cyclooctene with urea hydrogen peroxide (UHP). The highest conversion of cyclooctene with UHP in ethanol was obtained in the presence of b-tetra-brominated meso-tetraphenylporphyrinatomanganese(III) acetate (MnTPPBr 4 (OAc)). Therefore MnTPPBr 4 (OAc) has been selected for oxidation of different alkenes and alkanes. In order to achieve maximum conversion, the effect of different parameters such as solvent, temperature, amount of oxidant, acetic acid as oxidant activator and also the amount of axial base as co-catalyst were investigated.

Cu(II) and Ni(II) complexes of the general type [M(N 2 O 2 )] are described. The N 2 O 2 ligands used are [N,N -bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,Nbis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1 H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48 nm were formed by thermal reduction of [N,N -bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles.

Syntheses of soluble tetrabenzoporphyrins (TBP) and tetranaphtho [2,3]porphyrins (TNP), with multiple substituents in the conjugated aromatic rings but bearing no substituents in the mesopositions, is reported. Both types of porphyrins were obtained by direct aromatization of precursor porphyrins, annealed with either cyclohexene or dihydronaphthalene fragments. TBPs and TNPs possess powerful absorption bands in the near-infrared (λ ) 610-710 nm, ) 100,000-300,000 M -1 cm -1 ) and exhibit strong luminescence. Free bases and Zn complexes fluoresce with quantum yields of up to 50%, whereas Pd and Pt complexes phosphoresce in solutions at ambient temperatures. Remarkably, the phosphorescence quantum yields of Pd and Pt TBPs reach as high as 20-50%, which places them among the brightest near-infrared phosphors known to date. Klimant, I.; Frank, B.; Holst, G.; Wolfbeis, O. S. Appl. Spectrosc. 2000, 54, 548. (d) Minamitani, H.; Tsukada, K.; Sekizuka, E.; Oshio, C. J. Pharm. Sci. 2003, 93, 227. (e) Kress, M.; Meier, T.; Steiner, R.; Dolp, F.; Erdmann, R.; Ortmann, U.; Ruck, A.

A novel general synthetic route to tetraaryltetrabenzoporphyrins (Ar 4 TBP) with various peripheral functional groups is developed. The procedure includes (i) Barton-Zard condensation of 1-nitro-or 1-phenylsulfonylcyclohexenes with isocyanoacetic acid esters, (ii) condensation of the resulting 4,5,6,7-tetrahydroisoindoles with aromatic aldehydes to give fused tetraaryltetracylohexenoporphyrins (Ar 4 TCHP), and (iii) aromatization of the metal complexes of Ar 4 TCHP's into the corresponding Ar 4 TBP's. Cu and Zn complexes of Ar 4 TBP's are further demetalated to give the corresponding Ar 4 TBP free bases. The overall yields for the sequence range from 15% to 40%, making the method suitable for the preparation of gram quantities of Ar 4 TBP's in a single run. The scope of the method, the selection of the peripheral substituents, the choice of the metal ions, and their influence on the yields of aromatization are discussed. The basic spectroscopic properties of newly synthesized Ar 4 TBP's and Ar 4 TCHP's are reported together with the first X-ray crystallographic structure of the NiAr 4 TBP complex. Tsvirko, M. P.; Sapunov, V. V.; Soloviyev, K. N. Opt. Spektrosk. 1973, 34, 1094. d) Edwards, L.; Gouterman, M.; Rose, C. B. J. Am. Chem. Soc. 1976, 98, 7638. (e) Koehorst, R. B. M.; Kleibeuker, J. F.; Tjeerd, J. S.; de Bie, D. A.; Geursten, B.; Henrie, R. N.; van der Plas, H. C. J. Chem. Soc. 1981, 1005. (f) Aartsma, T. J.; Gouterman, M.; Jochum, C.; Kwiram, A. L.; Pepich, B. V.; Williams, L. D. Tsiguo, Y.; Osami, O.; Kunihiro, I.; Hisayuki, M.; Masako, S. Inorg. Chim. Acta 1991, 185, 39. (g) Liou, K. Y.; Newcomb, T. P.; Heagy, M. D.; Thompson, J. A.; Heuer, W. B.; Musselman, R. L.; Jacobsen, C. S.; Hoffman, B. M.; Ibers, J. A.

New mixed-substituent amino/carboxyphenylporphyrins for a dye-sensitized TiO 2 solar cell were prepared using several synthetic routes. The reaction of 4-carbomethoxy-and 4-acetamidobenzaldehydes with pyrrole in propionic acid under aerobic conditions afforded mixtures of mixed amide/ester substituted tetraphenylporphyrins which were separated using centrifugal chromatography then deprotected to give the target compounds. Condensation of p-nitrophenyldipyrromethane with 4-carbomethoxybenzaldehyde in CH 2 Cl 2 catalyzed by trifluoroacetic acid, followed by oxidation with dichlorodicyanoquinone gives trans-dicarbomethoxy/ dinitrophenylporphyrin, which when treated with SnCl 2 and HCl affords the trans-diamino/dicarboxy derivative, trans-TA 2 C 2 PP. Commercially available tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP) was converted to mixtures of mixed amino/carbomethoxyphenylporphyrins using hydroxylamine hydrochloride in polyphosphoric acid with methanol workup. Relative yields and product distributions from each route are discussed and the optoelectronic characteristics of the synthesized porphyrins were studied using UV-visible spectroscopy and cyclic voltammetry. Copyright

A biomimetic heterogeneous catalyst was prepared by immobilization of meso-tetrakis(4-carboxyphenyl)porphyrinatoiron(III) chloride (Fe(TCPP)Cl) on multiwalled carbon nano-tubes (MWCNTs). The anchored catalyst was characterized by transmission electron mi-croscopy, powder X-ray diffraction, ultravioletevisible, and Fourier transform infrared spectroscopy. The amount of Fe-porphyrin loaded on the nanotubes was estimated by atomic absorption spectroscopy The thermogravimetric analysis demonstrated that the catalyst was thermally stable up to almost 350 C, exhibiting high thermal stability. Oxidation of sulfides and phenols with urea hydrogen peroxide (UHP) in water was efficiently enhanced with excellent selectivity under the influence of [Fe(TCPP)Cl@MWCNT]. The title heterogeneous catalytic system facilitates a greener reaction because the reaction solvent is water and UHP is used as a safe oxidant.

New mixed-substituent amino/carboxyphenylporphyrins for a dye-sensitized TiO 2 solar cell were prepared using several synthetic routes. The reaction of 4-carbomethoxy-and 4-acetamidobenzaldehydes with pyrrole in propionic acid under aerobic conditions afforded mixtures of mixed amide/ester substituted tetraphenylporphyrins which were separated using centrifugal chromatography then deprotected to give the target compounds. Condensation of p-nitrophenyldipyrromethane with 4-carbomethoxybenzaldehyde in CH 2 Cl 2 catalyzed by trifluoroacetic acid, followed by oxidation with dichlorodicyanoquinone gives trans-dicarbomethoxy/ dinitrophenylporphyrin, which when treated with SnCl 2 and HCl affords the trans-diamino/dicarboxy derivative, trans-TA 2 C 2 PP. Commercially available tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP) was converted to mixtures of mixed amino/carbomethoxyphenylporphyrins using hydroxylamine hydrochloride in polyphosphoric acid with methanol workup. Relative yields and product distributions from each route are discussed and the optoelectronic characteristics of the synthesized porphyrins were studied using UV-visible spectroscopy and cyclic voltammetry. Copyright

A green and sustainable method for the oxidation of 1,3-dihydrobenzo[c] thiophenes to sulfones using metalloporphyrin complexes Two efficient methods are reported for the oxidation of 1,3-dihydrobenzo[c]thiophenes to sulfones in good to high yields using H 2 O 2 in the presence of catalytic amounts of porphyrin-based catalysts in ethanol or acetonitrile as solvents at room temperature. The presence of electron-donating or electron-withdrawing groups, in the benzene ring of 1,3-dihydrobenzo[c]thiophene, is well tolerated.

A new method of synthesis of meso-tetraaryltetranaphtho [2,3]porphyrins (Ar 4 TNP) has been developed. Ar 4 TNPs with peripheral functional groups are obtained by oxidative aromatization of meso-tetraarylporphyrins in which pyrrole units are fused with either octahydro-or dihydronaphthalene moieties. These precursor porphyrins are synthesized in four to five steps from readily available starting materials, such as naphthalene or 1,4-benzoquinone. The pathway originating in dihydronaphthalene, i.e., the "dialine" route, was found to be superior to the alternative "octaline" route in that it (1) enables the shortening of the overall reaction sequence, (2) has a broader scope in terms of the peripheral substitution in Ar 4 TNPs, and (3) affords higher yields of the target porphyrins. Pd complexes of the synthesized Ar 4 TNPs exhibit remarkably strong absorption bands at 710-720 nm ( ∼ 200 000 M -1 cm -1 ) and phosphoresce at room temperature with moderate quantum yields (φ ) 2-3%, λ max ) 900-1000 nm). The absorption maxima of naphthoporphyrins substituted with eight methoxy groups (Ar 4 TNP(OMe) 8 ) were found to be about 15-20 nm red shifted compared to the corresponding maxima of unsubstituted Ar 4 TNPs. The X-ray crystallographic data suggest that these spectral shifts are caused not by the differences in nonplanar distortions of the macrocycles but by the purely electronic effects of the substituents.

New mixed-substituent amino/carboxyphenylporphyrins for a dye-sensitized TiO 2 solar cell were prepared using several synthetic routes. The reaction of 4-carbomethoxy-and 4-acetamidobenzaldehydes with pyrrole in propionic acid under aerobic conditions afforded mixtures of mixed amide/ester substituted tetraphenylporphyrins which were separated using centrifugal chromatography then deprotected to give the target compounds. Condensation of p-nitrophenyldipyrromethane with 4-carbomethoxybenzaldehyde in CH 2 Cl 2 catalyzed by trifluoroacetic acid, followed by oxidation with dichlorodicyanoquinone gives trans-dicarbomethoxy/ dinitrophenylporphyrin, which when treated with SnCl 2 and HCl affords the trans-diamino/dicarboxy derivative, trans-TA 2 C 2 PP. Commercially available tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP) was converted to mixtures of mixed amino/carbomethoxyphenylporphyrins using hydroxylamine hydrochloride in polyphosphoric acid with methanol workup. Relative yields and product distributions from each route are discussed and the optoelectronic characteristics of the synthesized porphyrins were studied using UV-visible spectroscopy and cyclic voltammetry. Copyright

New mixed-substituent amino/carboxyphenylporphyrins for a dye-sensitized TiO 2 solar cell were prepared using several synthetic routes. The reaction of 4-carbomethoxy-and 4-acetamidobenzaldehydes with pyrrole in propionic acid under aerobic conditions afforded mixtures of mixed amide/ester substituted tetraphenylporphyrins which were separated using centrifugal chromatography then deprotected to give the target compounds. Condensation of p-nitrophenyldipyrromethane with 4-carbomethoxybenzaldehyde in CH 2 Cl 2 catalyzed by trifluoroacetic acid, followed by oxidation with dichlorodicyanoquinone gives trans-dicarbomethoxy/ dinitrophenylporphyrin, which when treated with SnCl 2 and HCl affords the trans-diamino/dicarboxy derivative, trans-TA 2 C 2 PP. Commercially available tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP) was converted to mixtures of mixed amino/carbomethoxyphenylporphyrins using hydroxylamine hydrochloride in polyphosphoric acid with methanol workup. Relative yields and product distributions from each route are discussed and the optoelectronic characteristics of the synthesized porphyrins were studied using UV-visible spectroscopy and cyclic voltammetry. Copyright

Cu(II) and Ni(II) complexes of the general type [M(N 2 O 2 )] are described. The N 2 O 2 ligands used are [N,N -bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,Nbis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1 H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48 nm were formed by thermal reduction of [N,N -bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles.