Synthesis of covalently linked unsymmetrical porphyrin pentads containing three different porphyrin subunits

The tetrafunctionalized AB3-type porphyrin building blocks containing two different types of functional groups with N4, N3O, N3S, and N2S2 porphyrin cores were synthesized by following various synthetic routes. The AB3-type tetrafunctionalized N4 porphyrin building block was synthesized by a mixed condensation approach, the N3S and N3O porphyrin building blocks by a mono-ol method, and N2S2 porphyrin building block by an unsymmetrical diol method. The tetrafunctionalized porphyrin building blocks were used to synthesize monofunctionalized porphyrin tetrads containing two different types of porphyrin subunits by coupling of 1 equiv of tetrafunctionalized N4, N3O, N3S, and N2S2 porphyrin building block with 3 equiv of monofunctionalized ZnN4 porphyrin building block under mild copper-free Pd(0) coupling conditions. The monofunctionalized porphyrin tetrads were used further to synthesize unsymmetrical porphyrin pentads containing three different types of porphyrin subunits by coupling 1 equiv of monofunctionalized porphyrin tetrad with 1 equiv of monofunctionalized N2S2 porphyrin building blocks under the same mild Pd(0) coupling conditions. The NMR, absorption, and electrochemical studies on porphyrin tetrads and porphyrin pentads indicated that the monomeric porphyrin subunits in tetrads and pentads retain their individual characteristic features and exhibit weak interaction among the porphyrin subunits. The steady state and time-resolved fluorescence studies support an efficient energy transfer from donor porphyrin subunit to acceptor porphyrin subunit in unsymmetrical porphyrin tetrads and porphyrin pentads.     

新型手性基团修饰的金属卟啉的合成及性质研究

合成了一种手性基团修饰的金属卟啉化合物[5-对(L-亮氨酰氧乙氧基)苯基-10, 15, 20-三苯基卟啉锌]. 通过元素分析、紫外可见光谱、红外光谱、圆二色光谱及核磁共振波谱对该化合物进行了较详细的表征. 同时, 采用分子力学方法搜索了主体的最低能量构象, 从理论上进一步解释实验结果. 利用Z扫描技术测定了该化合物的三阶非线性光学性质.     

四羟基苯基金属卟啉（MTHPP）／TiO2的合成及其光催化活性的研究

采用Alder法合成四羟基苯基卟啉,并用四种醋酸盐：醋酸锌,醋酸镍,醋酸铜,醋酸钴与原卟啉合成了相应4种金属卟啉（MTHPP）．采用金属卟啉为敏化剂,并与蒸汽热法制备的纯锐钛矿型TiO2作用,得到相应的金属卟啉敏化TiO2复合光催化剂．利用红外、紫外、SEM、和XRD对所得金属卟啉以及金属卟啉-TiO2复合光催化剂进行了表征和分析．结果表明,所合成的金属卟啉均为目标化合物,金属卟啉负载于TiO2表面,未改变TiO2的晶型和形貌．金属卟啉与TiO2之间存在氢键的作用力．可见光降解亚甲基蓝（MB）实验结果表明,用锌卟啉（ZnTHPP）敏化的复合催化剂性能最好,复合催化剂性质稳定,可重复使用多次．     

Preparation and Photophysical and Photoelectrochemical Properties of a Covalently Fixed Porphyrin–Chemically Converted Graphene Composite

Chemically converted graphene (CCG) covalently linked with porphyrins has been prepared by a Suzuki coupling reaction between iodophenyl‐functionalized CCG and porphyrin boronic ester. The covalently linked CCG–porphyrin composite was designed to possess a short, rigid phenylene spacer between the porphyrin and the CCG. The composite material formed stable dispersions in DMF and the structure was characterized by spectroscopic, thermal, and microscopic measurements. In steady‐state photoluminescence spectra, the emission from the porphyrin linked to the CCG was quenched strongly relative to that of the porphyrin reference. Fluorescence lifetime and femtosecond transient absorption measurements of the porphyrin‐linked CCG revealed a short‐lived porphyrin singlet excited state (38 ps) without yielding the porphyrin radical cation, thereby substantiating the occurrence of energy transfer from the porphyrin excited state to the CCG and subsequent rapid decay of the CCG excited state to the ground state. Consistently, the photocurrent action spectrum of a photoelectrochemical device with a SnO₂ electrode coated with the porphyrin‐linked CCG exhibited no photocurrent response from the porphyrin absorption. The results obtained here provide deep insight into the interaction between graphenes and π‐conjugated systems in the excited and ground states.     

新型手性金属卟啉的合成及非线性光学性质研究

本文合成了一种新型Boc(叔丁氧羰基)保护手性苏氨酸修饰的自由卟啉及其锌配合物。通过元素分析、紫外-可见光谱、荧光光谱、核磁共振氢谱、CD光谱等多种谱图对结构进行了表征,并结合理论计算采用模拟退火的方法搜索了手性锌卟啉配合物的最低能量构象。此外,利用Z-扫描技术测定了手性卟啉化合物的三阶非线性折射率。     

Anion chelation-induced porphyrin protonation and its application for chloride anion sensing

The protonation of a simple meso-tetraphenylporphyrin in an organic-aqueous system was found to be induced by the counteranions. During the process of protonation, the counteranion of the proton sources binds with the porphyrin core and thus promotes the complexation of the porphyrin and protons. The interaction of porphyrin and anion was characterized by fluorescence, UV-visible, cyclic voltammetry, (1)H NMR, and IR. Moreover, it could be exploited in selective fluorescent sensing of Cl(-). The sensing mechanism was based on extraction of protons from the aqueous phase into the organic phase by free base porphyrin and simultaneous coextraction of Cl(-), which promoted porphyrin protonation, and hence resulted in significant changes of the porphyrin fluorescence spectra. Selectivity trends turned out to be dependent upon the lipophilicity of anion and the binding affinity and structure complementarity between the protonated porphyrin and anions. The fluorescence enhancement of the porphyrin band at 684 nm showed modest selectivity for Cl(-) and NO(3)(-).     

A giant supramolecular light-harvesting antenna-acceptor composite

A giant light-harvesting antenna-acceptor composite was constructed by heterodimerization of imidazolylmanganese(III)porphyrin to molecular terminals of the zinc porphyrin array composed of meso-meso linked bis(imidazolylzincporphyrin). Fluorescence quenching titration indicated that the terminal imidazolylmanganase(III)porphyrin quenched excited zinc porphyrin separated by a large number of intervening porphyrins and that the meso-meso linked bis(imidazolylzincporphyrin) array was an efficient light-harvesting antenna.     

Preparation and photophysical and photoelectrochemical properties of a covalently fixed porphyrin-chemically converted graphene composite

Chemically converted graphene (CCG) covalently linked with porphyrins has been prepared by a Suzuki coupling reaction between iodophenyl-functionalized CCG and porphyrin boronic ester. The covalently linked CCG-porphyrin composite was designed to possess a short, rigid phenylene spacer between the porphyrin and the CCG. The composite material formed stable dispersions in DMF and the structure was characterized by spectroscopic, thermal, and microscopic measurements. In steady-state photoluminescence spectra, the emission from the porphyrin linked to the CCG was quenched strongly relative to that of the porphyrin reference. Fluorescence lifetime and femtosecond transient absorption measurements of the porphyrin-linked CCG revealed a short-lived porphyrin singlet excited state (38 ps) without yielding the porphyrin radical cation, thereby substantiating the occurrence of energy transfer from the porphyrin excited state to the CCG and subsequent rapid decay of the CCG excited state to the ground state. Consistently, the photocurrent action spectrum of a photoelectrochemical device with a SnO(2) electrode coated with the porphyrin-linked CCG exhibited no photocurrent response from the porphyrin absorption. The results obtained here provide deep insight into the interaction between graphenes and π-conjugated systems in the excited and ground states.     

轮古常渣及其组分中金属钒卟啉的分离与鉴定

采用改进的溶剂萃取方法对轮古常渣及其组分中的金属钒卟啉进行分离。结果表明,从轮古常渣中分离出的卟啉钒的质量分数为18.5%,从轮古常渣正庚烷可溶质和沥青质中分离出的卟啉钒的质量分数分别为68.0%和9.2%。用紫外-可见光谱对萃取出来的金属钒卟啉和甲磺酸脱金属后得到的游离卟啉进行表征。结果表明,轮古常渣及其正庚烷可溶质和沥青质中的金属钒卟啉主要是初卟啉。对轮古常渣中的游离卟啉进行基质辅助激光解吸电离飞行时间质谱分析证明,轮古常渣中的金属钒卟啉主要是初卟啉。     

卟啉/TiO2界面的相互作用研究

采用吸收光谱、荧光光谱和瞬态光伏技术研究了卟啉/TiO2体系的吸收光特性、荧光特性和光伏特性, 并研究了卟啉和TiO2之间的界面相互作用. 研究结果表明, 卟啉环在与钬原子结合前后与TiO2之间的作用不同, TiO2的粒径也影响界面的相互作用. 卟啉与粒径为10 nm的TiO2作用后, 能级发生了简并, 同时带隙发生了红移. 卟啉与粒径为56 nm的TiO2相互作用后只有特征吸收峰发生红移, 带隙和峰的数量几乎未发生变化. 这说明在粒径为10 nm的TiO2与卟啉的大π键之间出现了离域的相互作用, 这也被荧光光谱和瞬态光伏曲线所证实.     

EFFECT OF UVA AND BLUE LIGHT ON PORPHYRIN BIOSYNTHESIS IN EPIDERMAL CELLS*

Abstract— To study porphyrin biosynthesis in normal human keratinocytes and A431 cells derived from human epidermoid carcinoma, cultured cells were incubated with delta-aminolevulinic acid (ALA), the precursor of porphyrin synthesis, and accumulation of porphyrins was measured spectrofluorometrically. Both human keratinocytes and A431 cells accumulated porphyrins in a time-dependent and a dose-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated by both cell types. Porphyrin accumulation was enhanced by Ca Mg ethylene-diaminetetraacetic acid, a ferrochelatase inhibitor, and the enhancement was reversed by the addition of iron, suggesting the utilization of iron by ferrochelatase. The effect of light on porphyrin accumulation was evaluated by exposing the ALA-loaded A431 cells to ultraviolet-A (UVA) and blue light radiation, followed by continued incubation with ALA for 2–48 h. There was an enhancement of porphyrin accumulation 2–48 h after the radiation as compared with nonirradiated controls. Consistent with this finding, ferrochelatase activity decreased in these cells at 24 h and 48 h. These data demonstrate that human keratinocytes and A431 cells are capable of porphyrin biosynthesis, and that exposure of porphyrin-containing A431 cells to light, which includes the Soret band spectrum, decreases the ferrochelatase activity, which is responsible, at least in part, for the further increase in porphyrin level.     

Rh(III) porphyrins as building blocks for porphyrin coordination arrays: from dimers to heterometallic undecamers

The coordination chemistry of a Rh(III) porphyrin building block was investigated with a view to the construction of heterometallic arrays of porphyrins. The Rh(III) porphyrin was found to coordinate methanol in the solid state and weakly in CDCl(3) solution. Crystallization afforded five coordinate pi stacked Rh(III) porphyrins. The distribution of products from reaction of Rh(III) porphyrin with DABCO, 4,4'-bipyridine, and 4,4'-bipyrimidine could be displaced toward dimeric species by silica gel column chromatography or recrystallization which served to remove excess ligand. Weak coordination to nitriles was observed, although it was sufficiently strong to organize a dimeric complex of 5,5'-dicyano-2,2'-bipyridine in the solid state. Complexes with 4,4'-bipyrimidine and 5,5'-dicyano-2,2'-bipyridine possess uncoordinated chelating nitrogen atoms. Larger heterometallic porphyrin arrays were assembled using a combination of Sn(IV) and Rh(III) porphyrin coordination chemistry. A Sn(IV) porphyrin acted as a core around which were coordinated two isonicotinate groups, carboxylic acid functionalized porphyrins, or porphyrin trimer dendrons. Rh(III) porphyrins were coordinated to pyridyl groups at the periphery of these entities. In this way an eleven porphyrin array, with four different porphyrin metalation states, was assembled. The diamagnetic nature of both the Rh(III) and Sn(IV) porphyrins, the slow ligand exchange kinetics on the NMR time scale, and tight ligand binding permitted the porphyrin arrays to be analyzed by two-dimensional (1)H NMR techniques.     

一种新型二硒卟啉的合成及其与牛血清白蛋白的相互作用

以5-(4-羟基苯基)-10,15,20-三苯基卟啉和硒粉为原料,合成了新型二硒双卟啉,用紫外可见光谱（UV-Vis）,红外光谱（IR）,核磁共振氢谱（1H NMR）,高分辩质谱（HR-MS）对目标产物的结构进行了确认。同时,考察了新化合物与牛血清白蛋白(BSA)相互作用的荧光光谱,由实验数据求得该二硒双卟啉与BSA的结合常数Ksv＝3.35×104 L/mol。分析荧光结果表明二硒双卟啉与BSA之间发生了较强的静态猝灭。     

Porphyrin‐containing Polyimide with Enhanced Light Absorption and Photocatalysis Activity

A series of porphyrin‐containing polyimide (PI) photocatalysts were synthesized by a one‐step solvothermal method. Characterization results revealed that porphyrin was uniformly coupled into the PI framework through covalent bonding and the visible‐light absorption was greatly improved. The photodegradation activity of porphyrin‐containing PIs for methyl orange (MO) under visible light was enhanced significantly, with the highest pseudo‐first‐order rate constant 35 times higher than that of neat porphyrin and 10 times higher than that of porphyrin‐free PI. The enhancement is mainly attributed to an increased light harvesting accompanied by a varied HOMO level, which was clarified by control experiments, characterizations and theoretical calculations. This work provides an insight into multiple effects of dye molecules in dye‐containing heterogeneous photocatalysts.     

并入两个四氢键组装单体的卟啉衍生物的合成研究

报道了一个新的卟啉四氢键超分子聚合物组装单体29的合成研究。通过对 Gong等最近报道的四氢键二聚体组装板块进行修饰，合成了两个相应的新的苯甲酸 衍生物中间体11和21，以间－硝基苯甲醛为原料以较高产率合成了一个二硝基四苯 基卟啉26，氯化亚锡还原得到另－卟啉二胺中间体28。以DCC为缩合剂，该卟啉二 胺与其中一个酸11发生缩合反应得到相应卟啉组装单体目标分子29。化合物29在弱 极性溶剂中具有良好的溶解度。     

Synthesis of cationic porphyrin modified amino acids

Derivatives of amino acids bearing a porphyrin moiety on a side chain were synthesized by coupling a porphyrin to a glutamic acid side chain; the utility of these compounds was demonstrated by their use in solid-phase synthesis of a peptide bearing a cationic porphyrin and by studying its DNA-binding properties.     

Three-dimensionally arranged windmill and grid porphyrin arrays by AgI-promoted meso-meso block oligomerization

The syntheses of soluble windmill and grid porphyrin arrays through the AgI-promoted coupling reaction of 1,4-phenylene-bridged linear porphyrin arrays, which are comprised of a central ZnII beta-free porphyrin and flanking peripheral NiII beta-octaalkylporphyrins, are described. The coupling reaction is advantageous in light of its high regioselectivity occurring only at the meso-position of the ZnII beta-free porphyrin as well as its easy extension to large porphyrin arrays. The windmill porphyrin arrays in turn serve as an effective substrate for further coupling reactions, to give three-dimensionally arranged grid porphyrin arrays. Further the grid porphyrin 12-mer (a tetramer of the linear porphyrin trimer) was also coupled to afford grid porphyrins (24-mer, 36-mer, and 48-mer). These porphyrin arrays were isolated in a discrete form by repetitive GPC/HPLC (GPC= gel-permiation chromatography). Competitive experiments with three linear porphyrin trimers bearing different peripheral metalloporphyrins (ZnII, NiII, and Cull), and the trapping experiment of the radical cation at the peripheral porphyrin with AgNO2, suggested that an initial one-electron oxidation of the easily oxidizable peripheral ZnII beta-octaalkylporphyrin with an AgI ion and a subsequent endothermic hole transfer assist the generation of the radical cation at the central ZnII beta-free porphyrin. In all ZnII-metallated windmill porphyrin arrays, the energy level of the S1 state of the meso-meso-linked diporphyrin core is lower than that of the peripheral porphyrins, thereby allowing an energy flow from the peripheral porphyrins to the central diporphyrin core; this has been confirmed by measurements of fluorescence lifetimes and picosecond time-resolved fluorescence spectra. The excitation energy transfer in the arrays encourages their potential use as an light-harvesting antenna.     

Host-guest complexation effect of 2,3,6-tri-O-methyl-β-cyclodextrin on a C60-porphyrin light-to-photocurrent conversion system

In a light-to-photocurrent conversion system based on a C₆₀-porphyrin bilayer prepared by electrostatic alternate adsorption, porphyrin units in a porphyrin polymer have been isolated by cyclodextrin utilizing the host-guest interaction. In this system, a high quantum yield was achieved by suppression of self-quenching of porphyrin units.     

水溶性锰卟啉模拟酶体系快速混合停流谱研究

采用快速混合停流技术,考察了不同pH值条件下水溶性锰卟啉MnⅢ(TMPyP)与四种单氧给体m CPBA、KHSO5、NaOCl及H2O2构建的细胞色素P 450模拟酶体系催化氧化活性物种的生成及催化烯烃环氧化过程.低pH值时,主要生成四价锰氧中间体2;而在高pH值时,首先生成五价锰氧中间体1,该中间体再向四价中间体2转化.     

Methylammonium groups at the solid walls of nanometer-sized, water-filled monolayer gaps as binding sites for a tetraanionic porphyrin

Long-chain hydrosulfides containing two secondary amide functions and either electron-poor or electron-rich carbon-carbon double bonds were self-assembled on gold surfaces around a flat-lying, octaanionic porphyrin. Rigid and reactive surface monolayers with 2 nm-wide, porphyrin-based gaps were thus obtained. The gold electrodes were then immersed in water, and the double bonds on the gaps' surfaces reacted with methylamine. It was added to the double bonds either by Michael addition or by bromination with hypobromite followed by methylamine substitution. Only the double bonds at the border of the gaps were accessible to methylamine dissolved in the bulk water volume and could react. The walls of the rigid membrane gaps now contained methylammonium groups at the sites of the double bonds in defined heights. A tetracationic copper(II) porphyrinate could not diffuse any more into the gap and did not quench the fluorescence of the octaanionic porphyrin on the bottom of the gap. A tetraanionic porphyrin, on the other hand, was fixated by the ring of ammonium groups. The bound porphyrin then acted as molecular cover for the gap with respect to ferricyanide transport from bulk water to the electrode. It was removed by raising the pH to a value of 12, where the methylammonium groups were neutralized to amines. Lowering the pH to 7 again and addition of more of the anionic porphyrin reclosed the gap.The porphyrin "cover" should be localized at distances of 8-10 and 20 A from the bottom porphyrin by multiple charge interactions. The 8-10 A distance is ideal for studies of photoinduced electron transfer between two porphyrin monomers of different redox potential. Furthermore it was found, that redox-active tyrosine could be trapped in the water volume above the porphyrin on gold.