Chromogenic indicator for anion reporting based on an N-substituted oxoporphyrinogen

5,10,15,20-Tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen and its di-N-benzylated derivative are solvatochromic dyes capable of binding anionic species. The influence of solvent polarity and hydrogen bonding on their electronic absorption spectra was observed. Hydrogen bonding by the porphyrinogen amine protons of acetone solvent molecules could be observed in the solid state. The acetone solvate of N21N23-dibenzyl-5,10,15,20-tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen crystallized under anhydrous conditions in the space group P with cell dimensions a = 12.1693(11) A, b = 17.5849(13) A, c = 21.0965(17) A, alpha = 69.870(4) degrees , beta = 78.140(4) degrees , gamma = 82.865(5) degrees . These porphyrinogens are capable of binding a variety of anions and can be used to distinguish fluoride chromogenically from the other halide anions. Solvatochromism was combined with anion binding in an attempt to provide more selective tests for anions. The anion binding properties were investigated using UV/vis spectrophotometry and 1H NMR spectroscopy.     

Triplet pi-diradical dication of directly meso-beta-linked porphyrin dimer

Directly linked bisporphyrin, Zn(II)2 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)-2-(10,15,20-tris(3,5-di-tert-butylphenyl)porphyrin-5-yl)porphyrin, was investigated on the basis of the magnetic property of its bis(pi-radical cation). A stable triplet state of the bis(pi-radical cation) of the bisporphyrin, which obeys the Curie law, was successfully observed.     

1,3-Dioxopyrrolo[3,4-b]porphyrins: synthesis and chemistry

A novel 1,3-dioxopyrrolo[3,4-b]porphyrin (2) has been synthesized in 70% yield following a [4 + 2] cycloaddition reaction of pyrrolo[3,4-b]porphyrin 1 with (1)O(2). The new imide was used as a template to other 1,3-dioxopyrrolo[3,4-b]porphyrins and to the corresponding open counterparts. The UV/vis absorption spectra of the new compounds show significant red-shifts when compared with those of the nonsubstituted analogues. The structure of an imide derivative was confirmed by single-crystal X-ray diffraction.     

β to β Terpyridylene-bridged porphyrin nanorings

β β to Terpyridine bridged cyclic porphyrin dimer, trimer, tetramer and pentamer were obtained through one-pot Suzuki-Miyaura crossing coupling reaction in good yields with template free. These porphyrin nanorings possess high fluorescence quantum yields and large extinction coefficients.     

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。     

Ultrafast photoinduced electron transfer in directly linked porphyrin-ferrocene dyads

The ultrafast electron transfer occurring upon Soret excitation of three new porphyrin-ferrocene (XP-Fc) dyads has been studied by femtosecond up-conversion and pump-probe techniques. In the XP-Fc dyads (XP-Fcs) designed in this study, the ferrocene moiety is covalently bonded to the meso positions of 3,5-di-tert-butylphenyl zinc porphyrin (BPZnP-Fc), pentafluorophenyl zinc porphyrin (FPZnP-Fc), and 3,5-di-tert-butylphenyl free-base porphyrin (BPH2P-Fc). Charge separation and recombination in the XP-Fcs were confirmed by transient absorption spectra, and the lifetimes of the charge-separated states were estimated from the decay rate of the porphyrin radical anion band to be approximately 20 ps. The charge-separation rates of the XP-Fcs were found to be >10(13) s-1 from the S2 state and 6.3x10(12) s-1 from the S1 state. Charge separation from the S2 state was particularly efficient for BPZnP-Fc, whereas the main reaction pathway was from the S1 state for BPH2P-Fc. Charge separation from the S2 and S1 states occurred at virtually the same rate in benzene and tetrahydrofuran and was much faster than their solvation times. Analysis of these results using semiquantum Marcus theory indicates that the magnitude of the electronic-tunneling matrix element is rather large and far outside the range of nonadiabatic approximation. The pump-probe data show the presence of vibrational coherence during the reactions, suggesting that wavepacket dynamics on the adiabatic potential energy surface might regulate the ultrafast reactions.     

Solvent induced ordered-supramolecular assembly of highly branched protoporphyrin IX derivative

Protoporphyrin IX species bearing highly branched alkyl chains were self-assembled into well-defined nanostructures such as rod-like in CHCl₃–cylcohexane (1:9, v/v) and a honeycomb-like morphology in a polar solvent dimethyl sulfoxide (DMSO). The rod-like morphologies observed in the atomic force microscopy (AFM) and transmission electron microscopy (TEM) suggest that the lamellar phase self-organises into multilamellar vesicles. The X-ray diffraction (XRD) results indicate molecular arrangements resulting from longitudinal and transverse stacking of the porphyrin head groups in the lamellar structure. The typical nanostructures were derived from a high level of cooperativity between the porphyrin cores via π–σ interactions and supported by hydrogen bonding and van der Waals interactions. The nanostructures were characterised by means of UV–vis, fluorescence, AFM, TEM and XRD analysis. Our methodology confirms the potential of protoporphyrin IX derivatives in supramolecular chemistry.     

Two-dimensional assembly of functionalized 4-aryl-1-alkenyl-3,5-dioxo-1,2,4-triazolidines

Acid functionalized derivatives of 4-aryl-1-alkenyl-3,5-dioxo-1,24-triazolidines (4-arylurazoles), i.e. 4-(-but-1-en-3-yl-3, 5-dioxo-1,2,4-triazolidin-4-yl) benzoic acid (1), 4-urazoyl benzamide, i.e. 4-(1-but-1-en-3-yl-3, 5-dioxo-1,2,4-triazolidin-4-yl) benzamide (2), and 4-urazoylphenylazobenzoic acid, i.e. 4-(1-but-1-en-3-yl-3, 5-dioxo-1,2,4-triazolidin-4-yl) phenylazobenzoic acid (3), organize into two-dimensional supramolecular assemblies via intermolecular hydrogen bonding. Hydrogen bonds are formed between two acid (or amide) and two urazole groups, as well as between a carbonyl group of the urazole heterocycle and a hydrogen atom of the phenyl ring. These two-dimensional layers also persist if the polar groups are attached randomly to flexible polybutadiene chains.     

Synthesis and characterization of alkanethiolate-coordinated iron porphyrins and their dioxygen adducts as models for the active center of cytochrome p450: direct evidence for hydrogen bonding to bound dioxygen.

Two kinds of novel cytochrome P450 models, which have alkanethiolate axial ligands and hydroxyl groups inside molecular cavities, were designed and synthesized as functional O(2) binding systems. A superstructured porphyrin, designated as "twin-coronet" porphyrin, was used as the common framework of the model complexes. This porphyrin bears four binaphthalene bridges on the both sides and forms two pockets surrounded by the bulky aromatic rings. Thiobenzyloxy and thioglycolate moieties, which contain an alkanethiolate group exhibiting various electron-donating abilities and degrees of bulkiness, were covalently linked to twin-coronet porphyrin to yield thiolate-coordinated hemes, TCP-TB and TCP-TG (twin-coronet porphyrin with thiobenzyloxy and thioglycolate groups), respectively. Both ferric complexes exhibited high stability during usual experimental manipulation under air and were characterized by MS, UV/vis, ESR spectroscopies, and CV. The ESR spectra exhibited low-spin signals (TCP-TB: g = 2.334, 2.210, 1.959; TCP-TG: g = 2.313, 2.209, 1.966). The cyclic voltammogram of TCP-TB in CH(3)CN gave a quasi-reversible wave which corresponds to the Fe(III)/Fe(II) redox couple: E(p)()(/2) = -1.35 V (vs Fc/Fc(+)). On the other hand, TCP-TG showed a fine reversible wave: E(1/2) (Fe(III)/Fe(II)) = -1.12 V. The stable dioxygen adducts were formed in the reaction of the ferric complexes with KO(2) under an oxygen atmosphere and characterized by UV/vis and resonance Raman (RR) spectroscopies. In the RR spectra, the nu(O--O) bands of the dioxygen adducts were observed at 1138 cm(-1) (TCP-TB) and 1137 cm(-1) (TCP-TG). The hypothesis that hydrogen bonding between the bound oxygen and the hydroxyl groups of the binaphthyl moieties could increase their stability was verified by RR spectroscopy. When all hydroxyl groups were deuterated, only the frequencies of the nu(O--O) bands were upshifted by 2 cm(-1) without any perturbation in the porphyrin skeleton. This work shows the first direct evidence for a hydrogen bond to dioxygen in an oxy form of a thiolate-coordinated heme model system. These results are discussed in context of the process of dioxygen binding and activation in cytochrome P450.     

Supramolecular synthons and pattern recognition in adenine amides – synthesis,structures and thermal properties

An effective method for the synthesis of novel adenine amides was developed and successfully implemented, leading to 4-propyloxy-N-(9H-purin-6-yl)benzamide (1) and 4-dodecyloxy-N-(9H-purin-6-yl)benzamide (2). The compounds were fully characterised by means of spectroscopic (¹H NMR, ¹³C NMR, FT-IR) and thermal (TG, DSC) analysis. The crystallographic analysis revealed that the formation of supramolecular chains relies on hydrogen bonding between amide functionalities. All supramolecular synthons found in the crystal structure of 1 were confirmed with the temperature-dependent IR method. The temperature-dependent IR method is useful in determining supramolecular interactions for compound 2, for which the crystal structure could not be obtained. A detailed analysis of temperature-dependent FT-IR spectra was used for the first time to identify the hydrogen bonds that exist in the solid state of our compounds; it can therefore be considered a promising method for the pattern recognition of hydrogen bonding in supramolecular chemistry.     

基于双嘧啶和双巴比妥酸的氢键组装体的理论研究

用AM1方法对双嘧啶和双巴比妥酸以及二者以1:1的摩尔比通过分子间多重氢键自组织形成的二体进行了几何构型优化,得到氢键键能。并在此基础上用INDO-CI方法讨论了三者的UV-Vis光谱,结果与实验值符合得很好,证实了多重氢键导致新的超分子聚集体的生成,并讨论了氢键在超分子聚集体形成过程中的作用本质。     

Androgynous porphyrins. Silver(II) quinoxalinoporphyrins act as both good electron donors and acceptors

The metal-centered and macrocycle-centered electron-transfer oxidations and reductions of silver(II) porphyrins were characterized in nonaqueous media by electrochemistry, UV-vis spectroelectrochemistry, EPR spectroscopy, and DFT calculations. The investigated compounds are {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b']porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':7,8-b']porphyrinato}silver(II), and {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':12,13-b']porphyrinato}silver(II). The first one-electron oxidation and first one-electron reduction both occur at the metal center to produce stable compounds with Ag(III) or Ag(I) metal oxidation states, irrespective of the type of porphyrin ligand. The electrochemical HOMO-LUMO gap, determined by the difference in the first oxidation and first reduction potentials, decreases by introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle. This provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors, something not previously observed in other metalloporphyrin complexes. The second one-electron oxidation and second one-electron reduction of the compounds both occur at the porphyrin macrocycle to produce Ag(III) porphyrin pi-radical cations and Ag(I) porphyrin pi-radical anions, respectively. The macrocycle-centered oxidation potentials of each quinoxalinoporphyrin are shifted in a negative direction, while the macrocycle-centered reduction potentials are shifted in a positive direction as compared to the same electrode reactions of the porphyrin without the fused quinoxaline ring(s). Both potential shifts are due to a stabilization of the radical cations and radical anions by pi-extension of the porphyrin macrocycle after fusion of one or two quinoxaline moieties at the beta-pyrrolic positions of the macrocycle. Introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors.     

Luminescence enhancement and tuning via multiple cooperative supramolecular interactions in an ion-paired multinuclear complex

[(3,5-(CF(3))(2)Pz)(AgL)(2)](+)[Ag(5)(3,5-(CF(3))(2)Pz)(6)(CH(3)CN)](-) (L = 2-(N,N-diethylanilino-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine) shows bright and tunable emissions influenced by its supramolecular structure. Columnar stacks are assembled via cooperative interactions that include Ag(I)···Ag(I) argentophilic bonding, π···π stacking and Ag(I)···π interactions.     

Synthesis of porphyrins bearing uracyl groups and their assembly induced by melamine derivatives

Self‐assembled porphyrins via noncovalent bonding have attracted wide‐ranging researchers in material science. We reported herein the synthesis of the tetraphenyl porphyrin derivatives bearing uracyl groups as acceptor–donor–acceptor (ADA) type hydrogen bonding units, through the condensation of 5,10‐ or 5,15‐bis (3‐amino‐4‐ethylhexylphenyl) porphyrin derivatives with 6‐carboxyuracyl derivatives. When two porphyrins having uracyl groups at the different substituted positions were respectively mixed with a melamine derivative in benzene, ¹H NMR spectra showed that the 5,15 substituted uracyl porphyrin formed a hydrogen‐bonded suprastructure with the melamine derivative as a complementary molecule to the uracyl moiety, although the other 5,10‐substituted uracylporphyrin could not form such a structure. The SEM observation indicated that the mixture with the 5,15‐substituted uracyl porphyrin and the melamine with long alkyl chains formed a sheet‐like structure. Copyright © 2007 John Wiley & Sons, Ltd.     

Calix[4]arene-linked bisporphyrin hosts for fullerenes: binding strength, solvation effects, and porphyrin-fullerene charge transfer bands

A calix[4]arene scaffolding has been used to construct bisporphyrin ("jaws" porphyrin) hosts for supramolecular binding of fullerene guests. Fullerene affinities were optimized by varying the nature of the covalent linkage of the porphyrins to the calixarenes. Binding constants for C60 and C70 in toluene were explored as a function of substituents at the periphery of the porphyrin, and 3,5-di-tert-butylphenyl groups gave rise to the highest fullerene affinities (26,000 M(-1) for C60). The origin of this high fullerene affinity has been traced to differential solvation effects rather than to electronic effects. Studies of binding constants as a function of solvent (toluene < benzonitrile < dichloromethane < cyclohexane) correlate inversely with fullerene solubility, indicating that desolvation of the fullerene is a major factor determining the magnitude of binding constants. The energetics of fullerene binding have been determined in terms of DelatH and DeltaS and are consistent with an enthalpy-driven, solvation-dependent process. A direct relationship between supramolecular binding of a fullerene guest to a bisporphyrin host and the appearance of a broad NIR absorption band have been established. The energy of this band moves in a predictable manner as a function of the electronic structure of the porphyrin, thereby establishing its origin in porphyrin-to-fullerene charge transfer.     

Synthesis and binding ability of mono- and tetrasubstituted aminophosphonate Zn-tetraarylporphyrins towards N- and O-containing organic substrates

The 1,6-addition of mono- and tetra-amino 5,10,15,20-tetraphenylporphyrins with dimethyl-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidenemethyl)phosphonate leads to the corresponding mono- and tetrasubstituted aminophosphonate porphyrin derivatives. The binding ability of their Zn(II)-complexes towards 1,4-diazabicyclo[2,2,2]octane, imidazole, 4-(1H-imidazole-1-yl)benzyl alcohol and 4-(1H-imidazole-1-ylmethyl)benzyl alcohol in toluene was investigated by spectrophotometric and ¹H NMR titration. It has been determined that the monosubstituted Zn-tetraarylporphyrin is involved in a two-point selective binding of 4-(1H-imidazole-1-ylmethyl)benzyl alcohol. Taking into account the fact that this binding is accompanied by a clear and easily identifiable response in the UV–vis spectra of the reaction mixture, this metalloporphyrin could be considered as a molecular optical sensing device for selected bidentate N- and O-containing substrates.     

Construction of new cross-linked supramolecular polymer with FRET phenomenon based on oligo(p-phenylenevinylene)-linked pillar[5]arene dimer

Cross-linked supramolecular polymers generally show distinct mechanical properties with intriguing functions, which have become one of the hot research topics in recent years. However, the cross-linked supramolecular polymers functionalised with fluorescence resonance energy transfer (FRET) properties have been rarely reported yet. Herein, a new cross-linked supramolecular polymer equipped with efficient FRET property was constructed successfully. The oligo(p-phenylenevinylene)-linked pillar[5]arene dimer (PA-OPV) functioned as a host and energy donor, while four pentanenitrile groups coupled porphyrin (CN-Por) acted as guest with energy acceptor. The supramolecular polymerisation and FRET properties were investigated by using NMR, viscosity, Fluorescence, UV–vis and SEM.     

Synthesis and spectroscopy of a series of substituted N-confused tetraphenylporphyrins

A series of N-confused tetraphenylporphyrins (H(2)NCTPPs) with substituents on either the para- or the 3,5-positions of the meso phenyl rings were prepared using Lindsey conditions. Both electron-withdrawing and electron-donating groups were chosen in order to probe the effects of peripheral substitution on the properties of the macrocycles. The series includes 5,10,15,20-tetra-(4-R-phenyl) N-confused porphyrins (where R = bromo (1), iodo (2), cyano (3), methoxy (4), 2',5'-dimethoxyphenyl (5), or ethynyl (6)) and 5,10,15,20-(3,5-di-tert-butylphenyl) N-confused porphyrin (7). Absorption and steady-state fluorescence measurements were carried out, and quantum yields were measured for all compounds in both dichloromethane (CH(2)Cl(2)) and dimethylacetamide (DMAc).     

Porphyrin–TiO2 nanoparticle heterostructure assembly by Langmuir–Blodgett method

Surface pressure–area (π–A) isotherm characteristics of 5,10,15-(4-hydroxyphenyl)-20-(4-hexadecyloxyphenyl) porphyrin monolayers on both the water and TiO₂ hydrosol subphases, the UV–vis absorption and fluorescence spectra of the monolayers deposited onto CaF₂ substrates are investigated. π–A isotherms find that the porphyrin ring extends to lie more flat on a TiO₂ hydrosol surface than on a water surface. The UV–vis absorption spectra of the deposited monolayers prove that the porphyrin TiO₂ nanoparticle heterostructure assembly is formed, in which the J-aggregated effect of porphyrin is weakened, comparing with that in the monolayer deposited from water subphase. The fluorescence spectra show that the fluorescent emission quenching by the photoinduced electron transfer from the excited porphyrin molecule to TiO₂ nanoparticle, occurs under excitation in the Soret band region of porphyrin.     

Synthesis, structure and photophysical properties of two transitional metal supramolecular complexes

Two supramolecular complexes: [Co(2,6-PDC)(Hdmpz)3]·H2O (1) and [Zn(2,6-PDC)(Hdmpz)2] (2) {2,6-PDC=pyridine-2,6-dicarboxylic acid, Hdmpz=3,5-dimethylpyrazol}, self-assembles via O-H?O and N-H?O hydrogen bondings into supramolecular networks, which are characterized by elemental analyses, IR spectra and single crystal X-ray diffraction analysis. Both of them consist of two-dimensional networks that are stacked together by typical hydrogen bonding interactions (i.e. O-H?O and N-H?O), which often play important roles in the formation of low-dimensional into high-dimensional supramolecular networks. In addition, quantum chemistry calculations and surface photovoltage spectroscopy are performed firstly with the complexes.