Mechanistic studies of nitric oxide reactions with water soluble iron(II), cobalt(II), and iron(III) porphyrin complexes in aqueous solutions: implications for biological activity.

The reactions of nitric oxide and carbon monoxide with water soluble iron and cobalt porphyrin complexes were investigated over the temperature range 298-318 K and the hydrostatic pressure range 0.1-250 MPa [porphyrin ligands: TPPS = tetra-meso-(4-sulfonatophenyl)porphinate and TMPS = tetra-meso-(sulfonatomesityl)porphinate]. Large and positive DeltaS(double dagger) and DeltaV(double dagger) values were observed for NO binding to and release from iron(III) complexes Fe(III)(TPPS) and Fe(III)(TMPS) consistent with a dissociative ligand exchange mechanism where the lability of coordinated water dominates the reactivity with NO. Small positive values for Delta and Delta for the fast reactions of NO with the iron(II) and cobalt(II) analogues (k(on) = 1.5 x 10(9) and 1.9 x 10(9) M(-1) s(-1) for Fe(II)(TPPS) and Co(II)(TPPS), respectively) indicate a mechanism dominated by diffusion processes in these cases. However, reaction of CO with the Fe(II) complexes (k(on) = 3.6 x 10(7) M(-1) s(-1) for Fe(II)(TPPS)) displays negative Delta and Delta values, consistent with a mechanism dominated by activation rather than diffusion terms. Measurements of NO dissociation rates from Fe(II)(TPPS)(NO) and Co(II)(TPPS)(NO) by trapping free NO gave k(off) values of 6.3 x 10(-4) s(-1) and 1.5 x 10(-4) s(-1). The respective M(II)(TPPS)(NO) formation constants calculated from k(on)/k(off) ratios were 2.4 x 10(12) and 1.3 x 10(13) M(-1), many orders of magnitude larger than that (1.1 x 10(3) M(-1)) for the reaction of Fe(III)(TPPS) with NO.     

Electroprecipitation of Ag(II)/Ag(III) tetraphenylsulfonate porphyrin and electrocatalytic behavior of the films

The electrochemical precipitation on glassy carbon and gold electrodes of Ag(II) tetraphenylsulfonate porphyrin (Ag(II)TPPS) from aqueous HClO₄ solutions, is reported. Electrochemical quartz crystal microbalance (EQCM) results indicate the possible formation of an Ag(II)–Ag(III) porphyrin dimer species. This species is oxidized and reduced in two consecutive steps: oxidation at +0.31 and +0.36 V (vs. SCE) and reduction at +0.11 and +0.07 V. The films show catalytic behavior toward O₂ reduction in 10⁻² M HClO₄ at relatively low potentials (E<−0.1 V) but catalyze NO reduction at relatively high-reduction potentials (E<0.4 V). The electrochemical results seem to indicate that the catalytic cycle in the case of NO involves formation of Ag(II)TPPS–Ag(II)TPPS(NO)⁺ and its electroreduction to regenerate Ag(II)TPPS–Ag(III)TPPS and NO-reduction products.     

Raman and infrared spectral study of meso-sulfonatophenyl substituted porphyrins (TPPSn,n = 1, 2A, 2O, 3, 4)

Raman and IR spectra of the free base p-sulfonatophenyl and phenyl meso-substituted porphyrins [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4); 5,10,15-tris(4-sulfonatophenyl)-20-phenyl-porphyrin (TPPS3); 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2A); 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyrin (TPPS2O); and 5-(4-sulfonatophenyl)-10, 15,20-trisphenylporphyrin (TPPS1)] and their N-diprotonated derivatives (porphyrin diacids) were studied. The Raman spectra of the deuterated analogues of these porphyrins, in which the central hydrogen atoms were substituted with deuterium, were also measured. The observed vibrational bands were assigned on the basis of the deuteration shifts and compared with the structural analogues of these compounds. In IR spectra of the free-base porphyrins, the p-sulfonation of phenyl groups results in evident alteration for the phenyl modes and the porphyrin skeleton modes that are strongly coupled with phenyl vibrations. While the p-sulfonation of phenyl groups causes only slight changes for the high-frequency Raman bands (> 850 cm(-1)), dramatic shifts and band splitting were observed in the low-frequency region (< 500 cm(-1)) of Raman spectra. The observed differences of low-frequency Raman spectra were attributed to the alteration of the structure of the porphyrin ring, especially the CalphaCmCalpha bond-angles, by different meso-sulfonatophenyl substitutions. In addition, different packing style of TPPSn molecules in the aggregates is also responsible for the alteration of the vibrational spectra of the aggregated TPPSn.     

Oxygen atom transfer from nitrite mediated by Fe(III) porphyrins in aqueous solution

Aqueous solutions of the iron(III) porphyrin complex FeIII(TPPS) (1, TPPS = tetra(4-sulfonatophenyl)-porphyrinato) and nitrite ion react with various substrates S to generate the ferrous nitrosyl complex FeII(TPPS)(NO) (2) plus oxidized substrate. When S is a water-soluble sulfonated phosphine, the product is the resulting monoxide. When air is introduced to the product solutions, 2 is rapidly reoxidized to 1; however, even in the absence of air, there is a slow regeneration of the ferric species with concomitant production of nitrous oxide. Thus, in an anaerobic aqueous environment, FeIII(TPPS) catalyzes oxygen atom transfer from nitrite ion to substrates with the eventual formation of N2O.     

Fast nitroxyl trapping by ferric porphyrins

Iron(II) porphyrin nitrosyl complexes are obtained in high yields from the reaction of iron(III) porphyrins with the nitroxyl donors sodium trioxodinitrate and toluensulfohydroxamic acid. The reaction was found to proceed both in organic solvents and in aqueous media from iron(III) (meso-tetraphenyl) porphyrinate ([FeIII(TPP)]+) and iron(III) meso-tetrakis (4-sulfonatophenyl) porphyrinate ([FeIII(TPPS)]3-) or iron(III) protoporphyrin IX, respectively. The kinetic rate constant for the reaction of ([FeIII(TPPS)]3-) with sodium trioxodinitrate (kon) was estimated to be 1.00 +/- 0.04 x 107 M-1 s-1. As well as resulting in a versatile method for obtaining ferrous nitrosyl porphyrins, the reaction points at ferric porphyrins as efficient nitroxyl traps and provides a tool to model nitroxyl reactivity toward hemeproteins.     

Chiral conversion and memory of TPPS J-aggregates in complex micelles: PEG-b-PDMAEMA/TPPS

In the presence of tryptophan (Trp), complex micelles were prepared by 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) and poly(ethylene glycol)-block-poly(2-(dimethylamino)ethyl methylacrylate) (PEG-b-PDMAEMA) in aqueous solutions at pH 1.8. Different mixing sequences led to different morphologies. Spheres and nanorods of small size were obtained in sequence I (P/Trp+TPPS) where TPPS was added into the mixed solution of PEG-b-PDMAEMA and Trp. More nanorods of larger length were achieved in sequence II (TPPS/Trp+P) where the copolymer was added as the last component. Two types of supramolecular chirality of TPPS aggregates caused by mixing sequences were investigated. In (P/Trp+TPPS), the circular dichroism (CD) signal of H-band was in line with the chirality of Trp while that of J-band exhibited an opposite signal (Chirality I). In (TPPS/Trp+P), chiral signals at both H- and J-bands followed that of Trp (Chirality II). The conversion between the two types of chirality can be accomplished by modulating the molar ratio of the repeating units on block PDMAEMA to TPPS, or a cycle of pH 1.8-5.5-1.8 processing on the micelle solution. In addition, the supramolecular chirality can be memorized via strong electrostatic interaction with achiral copolymer even after removal of the chiral template, but only Chirality II can be cyclically "switched-off-on".     

Interaction of porphyrins with a dendrimer template: self-aggregation controlled by pH

The interaction between self-aggregated porphyrins such as 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and 5,10,15,20-tetrakis(4-phosphonatophenyl)porphyrin (TPPP), and a generation 5 (G5) PAMAM dendrimer template is governed by minute differences of porphyrin acido-basic properties. While at neutral pH both monomeric TPPS and TPPP form complexes with G5, decreasing pH did not lead to porphyrin ring protonation (pK(a) approximately 5) but rather to the preferential formation of H-aggregates (probably H-dimers), most likely due to protonation of the G5. Upon further acidification of the solution, this face-to-face orientation of the porphyrin units is being converted to edge-to-edge aligned J-aggregates with a tightly defined structure. This process starts by protonation of the porphyrin ring at pH below 2.3 and 2.8 for TPPS and TPPP, respectively. The AFM imaging of porphyrin/G5 nanostructures obtained at pH 0.7 shows the formation of long nanorods of TPPS with partially aggregated G5 and small aggregates of TPPP connected to individual G5 molecules.     

Kinetics and mechanism of the oxidation of water soluble porphyrin FeIIITPPS with hydrogen peroxide and the peroxomonosulfate ion

The overall six-electron oxidation of water soluble porphyrin Fe(III)TPPS by hydrogen peroxide and peroxomonosulfate ion was studied by the stopped-flow method with UV-vis detection. A three-step consecutive reaction was observed with two intermediates: Fe(III)TPPS --> Int(1)--> Int(2)--> products. The products were identified as the iron(iii) complex of the biliverdin analog formed from TPPS and 4-sulfobenzoic acid. All the rate constants with both oxidizing agents were determined. Intermediate Int(1) is proposed to be the species (TPPS (+))Fe(IV)=O. Although no unambiguous proposal for the structure of Int(2) can be made, it is most probably the product of the four-electron oxidation of the original Fe(III)TPPS, contains an iron-oxo center and has a dissociable proton with a pK of around 3.1. In spite of the protolytic equilibria occuring in the pH region 2-4, the kinetic observations do not show pH dependence.     

Spectrophotometric determination of copper with α, β, γ, δ-tetraphenylporphine trisulfonate

Water-soluble porphyrin, α, β, γ, δ-tetraphenylphorphine trisulfonate (TPPS, H₂R), was found to be a very useful agent for both the direct spectrophotometric determination and the photometric titration of copper(II). The molar absorptivity of H₄R²⁺ at 434 nm is 5.0·10⁵ and the spectrophotometric sensitivity is 0.00013 μg Cu cm^?2 for A=0.001. Beer's law is followed in the range 0.006 μg–0.06 μg Cu ml^?1. Among twenty-two elements examined, only zinc(II) seriously interfered. Acid dissociation constants and salt effects on the spectra of TPPS were evaluated.     

Ion-association aggregation of an anionic porphyrin at the liquid/liquid interface studied by second harmonic generation spectroscopy

Interfacial ion-association adsorption and aggregation of a water-soluble porphyrin, tetrakis(4-sulfonatephenyl)porphyrin (TPPS) diacid, which was promoted by a cationic cetyltrimethylammonium ion (CTA(+)), was studied by second harmonic generation (SHG) spectroscopy. Comparing the interfacial SH spectrum with the transmission absorption spectrum of TPPS in the aqueous solution elucidated the aggregation behavior of TPPS at the heptane/water interface. The time-dependent SHG spectra for TPPS aggregation and the interfacial tension lowering in the presence of CTA(+) were discussed on the basis of an electrostatic adsorption model. Then, it was suggested that TPPS diacid was highly concentrated by the ion-association with CTA(+) at the interface, which was the intermediate state before the final aggregated state.     

四-(4-苯基磺酸基)卟啉在反相微乳内相中的聚集行为

本文系统研究了四-(4-苯基磺酸基)卟啉(TPPS)在由聚乙二醇辛基苯基醚（TX-100）构筑的反相微乳液内相中的聚集行为。通过改变反相微乳水相液滴的pH值、粒径及TPPS的浓度,发现在反相乳液内相中TPPS的表观pKa明显小于在水溶液中的pKa（4.9）,并且,TPPS的表观pKa随着水相液滴粒径的减小而降低;当水相液滴的pH > pKa时,TPPS以去质子化单体H2TPPS4-形式存在,而当pH < pKa时,TPPS以质子化单体H4TPPS2-和J-聚集两种形式存在,并且TPPS浓度的增大,促进了H4TPPS2-向J-聚集转变;在pH值不变的条件下,随着水相液滴粒径的增大,TPPS的存在状态由H2TPPS4-向H4TPPS2-转变,并形成J-聚集。     

Study on the supramolecular system of meso-tetrakis (4-sulfonatophenyl) porphyrin and cyclodextrins by spectroscopy

The ability of beta-cyclodextrin (beta-CD), sulfurbutylether-beta-CD (SBE-beta-CD) and hydroxypropyl-beta-CD (HP-beta-CD) to break the aggregate of the meso-Tetrakis (4-sulfonatophenyl) porphyrin (TPPS4) and to form 2:1 inclusion complexes has been studied by adsorption and fluorescence spectroscopy. The formation constants are calculated, respectively by fluoremetry, from which the inclusion capacity of different CDs is compared and the inclusion mechanism of charged-beta-CD (SBE-beta-CD) is quite different from that of parent beta-CD. At lower pH, the complexation between HP-beta-CD and H2TPPS(2+)4 (the form of the diprotonated TPPS4) hampers the continuous protonation of the pyrrole nitrogen of TPPS4 and the hydrophobic cavity may prefer to bind an apolar neutral porphyrin molecule. 1HNMR data support the inclusion conformation of the porphyrin-cyclodextrin supramolecular system, indicating the interaction of meso-phenyl groups of TPPS4 with the cavity of CDs. For this host-guest inclusion model, cyclodextrin, being regarded as the protein component, which acts as a carrier enveloping the active site of heme prosthetic group within its hydrophobic environment, provides a protective sheath for porphyrin, creating artificial analogues of heme-containing proteins. However, the TPPS4, encapsulated within this saccharide-coated barrier, its physico-chemical, photophysical and photochemical properties changed strongly.     

不同类型卟啉自组装膜的制备及表征

制备了不同类型的巯基卟啉自组装膜,借助多种表征技术（紫外可见光谱、电化学和X射线光电子能谱）研究了不同类型卟啉自组装膜的结构特点;研究结果表明,卟啉分子中巯基取代基数目的不同（-[SH]n-,n=1,4）,导致了卟啉环在自组装膜表面的构型不同,从而表现出不同巯基卟啉自组装膜性能的差异。 在此基础上,提出了不同巯基卟啉自组装膜的结构模型。     

阳离子表面活性剂存在下卟啉聚集的光谱研究

报导在阳离子表面活性剂溴化十六烷基三甲铵（CTMAB）存在下mcso-四（对-磺基苯基）卟啉（TPPS_4）发生聚集的电子吸收光谱、荧光光谱和共振光散射光谱特性．结果表明：CTMAB低于1．0×10~(－5)mol·L~(-1)时TPPS_4发生J-型聚集，形成一种交错卡迭式二聚体。在1．0×10~(－5)～1.0×10~(－4)mol·L~(－1)时，J-型聚集产物仍然存在，但TPPS_4的Soret蜂蓝移．如果CTMAB浓度高于1．0×10~（-4）mol·L~（-1），J-型聚集产物消失，出现游离碱卟啉的D_(2h)。吸收特征．相对于水介质，游离碱卟啉的Soret带在CTMAB胶束中红移．     

Spectrophotometric study of the interaction of tetraphenylporphyrin tetrasulfonate (TPPS4) with proteins

The interaction of water-soluble porphyrin TPPS(4) (tetraphenylporphyrin tetrasulfonate) with proteins in acidic solution was studied by spectrophotometry. The absorption spectra of TPPS(4)-protein complexes, the aggregation of TPPS(4) in acidic solution, and comparison of the absorption spectra of TPPS(4)-protein conjugate with that of the TPPS(4)-protein complex was investigated in detail. The effects of denaturants including urea and SDS were also examined. A mechanism was proposed that TPPS(4) would be distributed between microphase of protein and the aqueous solution and then aggregated in the microphase.     

meso-四(4-磺酸基苯基)卟啉-铬黑T与铁(Ⅲ)混合显色反应的研究

本文研究了以铬黑T作TPPS_4和Fe(Ⅲ)的混合配位体,并在弱酸性条件下运用了铬黑T,首次突破了Fe(Ⅲ))与TPPS_4的成络反应条件:在pH4.0的HAc-NaAc缓冲溶液中,沸水浴加热15min,以1:1:1的组成形成TPPS_4-铬黑T-Fe(Ⅲ)混配络合物,λ_(max)=392um,ε＇=2.07×10~5L·mol~(-1)·cm~(-1),稳定常数为8.7×10~7,Fe(Ⅲ)含量在0～4.5μg/25ml范围内成线性关系.将此方法用于纯铜、茶叶、烟草样品中的痕量铁的测定,获得了较满意的结果.     

Construction of porphyrin-cyclodextrin self-assembly with molecular wedge

A new host porphyrin bearing four permethyl-beta-cyclodextrin moieties for multi-porphyrin assembly forms a unique 2 : 2 assembly with the tetra-anion of tetrakis(p-sulfonylphenyl)porphyrin (TPPS) in aqueous solution.     

meso-四(4-磺基苯基)卟啉(TPPS)在水及胶束体系中的二聚行为研究

研究了meso-四（4-磺基苯基）卟啉（TPPS）在胶束（TritonX－100）、KCl水溶液中的电子吸收光谱变化,计算了TPPS的二聚常数KD,用分光光度法研究了TPPS在KCI水溶液中的二聚反应动力学,提出了与实验结果相吻合的二聚机理．根据温度对二聚平衡的影响,计算了二聚平衡的乙和     

Rh(DMF)TPPS.5H2O的合成及光助还原水放氢的研究

为筛选光解水产氢的光敏剂, 用改进的方法, 分别合成了Rh4(CO)12和meso-四(对苯磺酸钠)卟啉(TPPS), 并在N,N-二甲基甲酰胺(DMF)中反应, 得到组成为Rh(DMF)TPPS.5H2O的新配合物, 用元素分析, 红外, 拉曼光谱, 质子核磁共振, 电子顺磁共振及热重分析, 确定了配合物的结构和Rh的价态, 并进行了Rh(DMF)TPPS-TiCl3-K2PtCl6三组份复合体系的放氢实验, 结果表明铑体系较诸钌体系有更高的放氢效率.     

Porphyrin J-aggregates stabilized by ferric myoglobin in neutral aqueous solution

J-aggregates of a diacid form (H4TPPS2-) of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4-) were stabilized by binding with ferric myoglobin (metMb) in aqueous solution at neutral pH. The J-aggregates gradually dissociated to monomeric H2TPPS(4-). The average half-lifetime (t1/2) of the J-aggregates in the presence of sufficient amounts of metMb was ca. 3 h in phosphate buffer at pH 7.0 and 25 degrees C. The stabilization of the J-aggregate by metMb is ascribed to encapsulation and fixation of an edge-to-edge structure of the J-aggregate by the relatively rigid protein molecules. The secondary structure of metMb was altered in some extent in the presence of an excess amount of the J-aggregates while no effect on denaturation of metMb was observed with the H2TPPS(4-) monomer or polyacrylate. The hydrophobic nature of the J-aggregate seems to play an important role for denaturation of metMb. The ability of denatured metMb to bind the azide anion was higher than that of natural metMb. The denaturation of metMb by the J-aggregates seems to induce surfacing of hemin leading to an entropy gain in coordination of the N3(-) anion to the iron(III) center.