A highly enantiopure biconcave porphyrin with effective D4-structure

A first representative of an effectively D4-symmetric biconcave porphyrin (1) was prepared from a tetramerizing condensation of a C2-symmetric pyrrole (2). The chiral pyrrole 2 was synthesized in a six-step reaction sequence starting from the C2h-symmetric 2,6-di-tert-butylanthracene. The relevant stereochemistry was introduced in a highly diastereo-discriminating Diels-Alder reaction with fumaric acid di(-)menthyl ester, catalyzed by aluminum chloride. X-ray analyses of two of the dimenthyl esters prepared unambiguously secured their tentatively assigned absolute configuration and that of the pyrrole 2 (as the S,S isomer). The enantiomeric purity of the pyrrole 2 was determined as 99% ee, using the Co11 complex of the porphyrin 1 as a chiral shift reagent. The pyrrole 2 lent itself to a stereochemically nearly uniform preparation of the chiral, biconcave porphyrin 1. Applying Horeau's principle, 1 was calculated to be present in an enantiomeric excess of about 10(9):1. The validity of the statistical considerations relevant for this estimate were verified by examination of the results from preparative tetramerization experiments in which the enantiomeric purity of the pyrrole 2 was deliberately lowered.     

Siamese‐Twin Porphyrin: A Pyrazole‐Based Expanded Porphyrin of Persistent Helical Conformation

The 3+3‐type synthesis of a pyrazole‐based expanded porphyrin 22 H₄ , a hexaphyrin analogue named Siamese‐twin porphyrin, and its homobimetallic diamagnetic nickel(II) and paramagnetic copper(II) complexes, 22 Ni₂ and 22 Cu₂ , are described. The structure of the macrocycle composed of four pyrroles and two pyrazoles all linked by single carbon atoms, can be interpreted as two conjoined porphyrin‐like subunits, with the two opposing pyrazoles acting as the fusion points. Variable‐temperature 1D and 2D NMR spectroscopic analyses suggested a conformationally flexible structure for 22 H₄ . NMR and UV/Vis spectroscopic evidence as well as structural parameters proved the macrocycle to be non‐aromatic, though each half of the molecule is fully conjugated. UV/Vis and NMR spectroscopic titrations of the free base macrocycle with acid showed it to be dibasic. In the complexes, each metal ion is coordinated in a square‐planar fashion by a dianionic, porphyrin‐like {N₄} binding pocket. The solid‐state structures of the dication and both metal complexes were elucidated by single‐crystal diffractometry. The conformations of the three structures are all similar to each other and strongly twisted, rendering the molecules chiral. The persistent helical twist in the protonated form of the free base and in both metal complexes permitted resolution of these enantiomeric helimers by HPLC on a chiral phase. The absolute stereostructures of 22 H₆ ²⁺, 22 Ni₂ , and 22 Cu₂ were assigned by a combination of experimental electronic circular dichroism (ECD) investigations and quantum‐chemical ECD calculations. The synthesis of the first member of this long‐sought class of expanded porphyrin‐like macrocycles lays the foundation for the study of the interactions of the metal centers within their bimetallic complexes.     

Molecular structures and magnetic resonance spectroscopic investigations of highly distorted six-coordinate low-spin iron(III) porphyrinate complexes.

Three bis-axially ligated complexes of iron(III) octaethyltetraphenylporphyrin, (OETPP)Fe(III), have been prepared, which are low-spin complexes, each with two axial nitrogen-donor ligands (N-methylimidazole (N-MeIm), 4-(dimethylamino)pyridine (4-NMe(2)Py), and 2-methylimidazole (2-MeImH)). The crystal and molecular structure of the bis-(2-MeImH) complex shows the macrocycle to be in a saddled conformation, with the ligands in perpendicular planes aligned at 14 degrees to the porphyrin nitrogens so as to relieve the steric interaction between the 2-methyl groups and the porphyrin. The Fe-N(por) bond lengths are typical of nonplanar six-coordinate low-spin Fe(III) complexes, while the axial Fe-N(ax) bond lengths are substantially longer than those of [(TPP)Fe(2-MeImH)(2)](+) (2.09(2) A as compared to 2.015(4) and 2.010(4) A). The crystal and molecular structure of the bis-(4-NMe(2)Py) complex also shows the macrocycle to be in a mainly saddled conformation, but with a significant ruffled component. As a result, the average Fe-N(por) bonds are significantly shorter (1.951 A as compared to 1.974 A) than those of the bis-(2-MeImH) complex. One ligand is aligned at 9 degrees to two trans porphyrin nitrogens, while the other is at 79 degrees to the same porphyrin nitrogens, producing a dihedral angle of 70 degrees between the ligand planes. The EPR spectrum of this complex, like that of the bis-(2-MeImH) complex, is of the "large g(max)" type, with g(max) = 3.29 and 3.26, respectively. However, in frozen CD(2)Cl(2), [(OETPP)Fe(N-MeIm)(2)](+) exhibits both "large g(max)" and normal rhombic signals, suggesting the presence of both "perpendicular" and "parallel" ligand orientations. The 1- and 2D (1)H NMR spectra of each of these complexes, as well as the chloroiron(III) starting material, were investigated as a function of temperature. The COSY and NOESY/EXSY spectra of the chloride complex are consistent with the expected J-coupling and saddle inversion dynamics, respectively. Complete spectral assignments for the bis-(N-MeIm) and -(4-NMe(2)Py) complexes have been made using 2D (1)H NMR techniques. In each case, the number of resonances due to methylene (two) and phenyl protons (one each) is consistent with D(2)(d)() symmetry, and therefore an effective perpendicular orientation of the axial ligands on the time scale of the NMR experiments. The temperature dependences of the (1)H resonances of these complexes show significant deviations from Curie behavior, and also evidence of extensive ligand exchange and rotation. Spectral assignment of the eight methylene resonances of the bis-(2-MeImH) complex to the four ethyl groups was possible through the use of 2D (1)H NMR techniques. The complex is fluxional, even at -90 degrees C, and ROESY data suggest that the predominant process is saddle inversion accompanied by simultaneous rotation of the axial ligands. Saddle inversion becomes slow on the 2D NMR time scale as the temperature is lowered in the ligand order of N-MeIm > 4-NMe(2)Py > 2-MeImH, probably due mainly to progressive destabilization of the ground state rather than progressive stabilization of the transition state of the increasingly "hindered" bis-ligand complexes.     

Spectral, structural, and electrochemical properties of ruthenium porphyrin diaryl and aryl(alkoxycarbonyl) carbene complexes: influence of carbene substituents, porphyrin substituents, and trans-axial ligands

A wide variety of ruthenium porphyrin carbene complexes, including [Ru(tpfpp)(CR(1)R(2))] (CR(1)R(2) = C(p-C(6)H(4)Cl)(2) 1 b, C(p-C(6)H(4)Me)(2) 1 c, C(p-C(6)H(4)OMe)(2) 1 d, C(CO(2)Me)(2) 1 e, C(p-C(6)H(4)NO(2))CO(2)Me 1 f, C(p-C(6)H(4)OMe)CO(2)Me 1 g, C(CH==CHPh)CO(2)CH(2)(CH==CH)(2)CH(3) 1 h), [Ru(por)(CPh(2))] (por=tdcpp 2 a, 4-Br-tpp 2 b, 4-Cl-tpp 2 c, 4-F-tpp 2 d, tpp 2 e, ttp 2 f, 4-MeO-tpp 2 g, tmp 2 h, 3,4,5-MeO-tpp 2 i), [Ru(por)[C(Ph)CO(2)Et]] (por=tdcpp 2 j, tmp 2 k), [Ru(tpfpp)(CPh(2))(L)] (L = MeOH 3 a, EtSH 3 b, Et(2)S 3 c, MeIm 3 d, OPPh(3) 3 e, py 3 f), and [Ru(tpfpp)[C(Ph)CO(2)R](MeOH)] (R = CH(2)CH==CH(2) 4 a, Me 4 b, Et 4 c), were prepared from the reactions of [Ru(por)(CO)] with diazo compounds N(2)CR(1)R(2) in dichloromethane and, for 3 and 4, by further treatment with reagents L. A similar reaction of [Os(tpfpp)(CO)] with N(2)CPh(2) in dichloromethane followed by treatment with MeIm gave [Os(tpfpp)(CPh(2))(MeIm)] (3 d-Os). All these complexes were characterized by (1)H NMR, (13)C NMR, and UV/Vis spectroscopy, mass spectrometry, and elemental analyses. X-ray crystal structure determinations of 1 d, 2 a,i, 3 a, b, d, e, 4 a-c, and 3 d-Os revealed Ru==C distances of 1.806(3)-1.876(3) A and an Os==C distance of 1.902(3) A. The structure of 1 d in the solid state features a unique "bridging" carbene ligand, which results in the formation of a one-dimensional coordination polymer. Cyclic voltammograms of 1 a-c, g, 2 a-d, g-k, 3 b-d, 4 a, b, and 3 d-Os show a reversible oxidation couple with E(1/2) values in the range of 0.06-0.65 V (vs Cp(2)Fe(+/0)) that is attributable to a metal-centered oxidation. The influence of carbene substituents, porphyrin substituents, and trans-ligands on the Ru==C bond was examined through comparison of the chemical shifts of the pyrrolic protons in the porphyrin macrocycles ((1)H NMR) and the M==C carbon atoms ((13)C NMR), the potentials of the metal-centered oxidation couples, and the Ru==C distances among the various ruthenium porphyrin carbene complexes. A direct comparison among iron, ruthenium, and osmium porphyrin carbene complexes is made.     

A self-assembled porphyrin-based dimeric capsule constructed by a Pd(II)-pyridine interaction which shows efficient guest inclusion

Novel self-assembled molecular capsules were constructed from two moles of pyridine-containing porphyrin derivatives and four moles of Pd(II) complexes utilizing a pyridine-Pd(II) interaction. The (1)H NMR spectral studies established that these self-assembled molecular capsules 5 and 6 have a highly symmetrical D(4)(h)() structure as well as a large inside cavity. It was shown that molecular capsule 6 can include a large bipyridine guest by a two-point simultaneous pyridine-Zn(II) interaction.     

N-porphyrinylamino and -amido compounds by addition of an amino or amido nitrogen to a porphyrin meso position

This report describes the synthesis and characterization of a series of octaethylporphyrin derivatives in which the porphyrin pi-network is connected to phenyl, 3-fluoranthenyl, or 1-pyrenyl aromatic systems through a meso amino or amido nitrogen. Metal-free bases and zinc(II) and iron(III) complexes have been obtained. These compounds represent the first examples of linkages between porphyrins and extended pi-networks through a nitrogen atom directly attached to a porphyrin meso position. 1H NMR studies of the metal-free bases and zinc complexes showed that in the amido-linked adducts, the plane containing the aryl substituent was oriented perpendicular to the plane of the porphyrin. Linkage through the secondary amino nitrogen, however, allowed the aryl plane to rotate toward coplanarity with the porphyrin plane, resulting in conjugation of the highest occupied aryl and porphyrin molecular orbitals through the nitrogen lone pair. In developing routes to the amino-linked compounds, the facile formation of fused azaaryl chlorins via an oxidative intramolecular cycloaddition was observed. An aryl carbon ortho to the meso linkage attacked the beta-carbon of an adjacent pyrrole ring, accompanied by 1,2-migration of a pyrrole beta-ethyl substituent and a two-electron oxidation of the initially formed macrocycle. The resulting structures are analogous to benzochlorins. The electronic spectra of the metal-free bases are characterized by intense, long-wavelength bands in the visible region. Molecular structures of the chloroferric complexes of the azabenzofluorantheno- and azabenzpyrenoporphyrin macrocycles (derived from fusion of the fluoranthenyl and pyrenyl substituents, respectively) were obtained by X-ray diffraction. The porphyrin moiety in the azabenzofluoranthenoporphyrin adopted a gable structure, with a 22 degrees fold along a diagonal including the pyrrole-ring C4 and C16 alpha-carbons. By contrast, the azabenzpyrenoporphyrin was virtually planar.     

Synthesis and characterization of intermediate sitting-atop (i-SAT) complexes of free base meso-tetraarylporphyrins and tin(IV) chloride

The reaction of meso-tetraarylporphyrins (H₂T(X)PP) with SnCl₄ affords green intermediate sitting-atop (i-SAT) complexes, [(H₂T(X)PP)SnCl₄]. UV–Vis, ¹H NMR and ¹³C NMR spectral data show that the porphyrin core of the complexes is distorted, thus two nitrogen atoms of the pyrrolenine groups on one side of the porphyrin plane act as electron donors to the tin center of SnCl₄. The intermediate sitting-atop (i-SAT) complex is formed each time during the incorporation of the metal center, where in the intermediate state the pyrrolic protons still remain on the porphyrin.     

Disproportionation of Iron(III) Porphyrin pi-Cation Radicals in the Presence of Sterically Hindered Pyridines. Spectroscopic Detection of Asymmetric Highly Oxidized Intermediates

The reactivity of iron(III) tetraphenylporphyrin pi-cation radical (TPP(*))Fe(III)(ClO(4))(2), (1-1) iron(III) tetra-p-tolylporphyrin pi-cation radical (TTP(*))Fe(III)(ClO(4))(2) (1-2) and iron(III) tetramesitylporphyrin pi-cation radical (TMP(*))Fe(III)(ClO(4))(2) (1-3) complexes with 2,4,6-collidine, 2,3,6-collidine, 2-picoline, 2,6-di-tert-butylpyridine, and 2,6-dibromopyridine has been examined by (1)H NMR spectroscopy in dichloromethane-d(2) solution at low temperatures. These complexes undergo hydration processes which are essential in the generation of highly oxidized species via acid base/equilibria of coordinated water followed by disproportionation pathway, giving as sole stable products [(TPP(*))Fe(III)OFe(III)(TPP)](+) (4-1), [(TTP(*))Fe(III)OFe(III)(TTP)](+) (4-2), and (TMP)Fe(III)(OH) (6) respectively. The sterically hindered pyridines act as efficient proton scavengers. Two novel highly oxidized iron complexes have been detected by (1)H NMR spectroscopy after addition of 2,4,6-collidine to (TTP(*))Fe(III)(ClO(4))(2) or (TPP(*))Fe(III)(ClO(4))(2) in dichloromethane-d(2) solution at 202 K. New intermediates have been identified as iron porphyrin N-oxide complexes, i.e., iron(III) porphyrin N-oxide cation radical (2-n) and iron(IV) porphyrin N-oxide radical (3-n). The (1)H NMR results indicate that the D(4)(h)() symmetry of the parent iron(III) pi-cation radical is drastically reduced upon disproportionation in the presence of proton scavengers. Both species are very unstable and were observed from 176 to 232 K. The intermediate 2-2 has a (1)H NMR spectrum which demonstrates large hyperfine shifts (ppm) for the meso p-tolyl substituents (ortho 98.0, 94.8, 92.9, 91.7; meta -34.8, -38.7, -41.5, -42.3; p-CH(3) -86.3, -88.0) which are consistent with presence of an N-substituted iron porphyrin radical in the product mixture. The characteristic (1)H NMR spectrum of 2-2 includes six pyrrole resonances at 149.6, 118.2, 115.4, 88.3, 64.6, and 55.7 ppm at 202 K, i.e., in the positions corresponding to iron(III) high-spin porphyrins. On warming to 222 K, the pyrrole resonances broaden and then coalesce pairwaise. Such dynamic behavior is accounted for by a rearrangement mechanism which involves an inversion of the porphyrin puckering. The pattern of p-tolyl resonances revealed the cation radical electronic structure of 3-2. The p-tolyl resonances are divided in two distinct sets showing opposite direction of the isotropic shift for the same ring positions. The pyrrole resonances of 3-2 also demonstrated downfield and upfield shifts. A disproportionation mechanism of the hydrated iron porphyrin cation radicals to generate 2 and 3 has been proposed. Both intermediates react with triphenylphosphine to produce triphenylphosphine oxide and high-spin iron porphyrins. Addition of 2,4,6-collidine to (TMP(*))Fe(III)(ClO(4))(2) does not produce analogs of 2 and 3 found for sterically unprotected porphyrins. It results instead in the formation of a variety of X(TMP(*))Fe(IV)O (5) complexes also accounted for by the disproportionation process.     

Mechanistic studies of (porphinato)iron-catalyzed isobutane oxidation. Comparative studies of three classes of electron-deficient porphyrin catalysts

We report herein a comprehensive study of (porphinato)iron [PFe]-catalyzed isobutane oxidation in which molecular oxygen is utilized as the sole oxidant; these catalytic reactions were carried out and monitored in both autoclave reactors and sapphire NMR tubes. In situ 19F and 13C NMR experiments, coupled with GC analyses and optical spectra obtained from the autoclave reactions have enabled the identification of the predominant porphyrinic species present during PFe-catalyzed oxidation of isobutane. Electron-deficient PFe catalysts based on 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin [(C6F5)4PH2], 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl) porphyrin [Br8(C6F5)4PH2], and 5,10,15,20-tetrakis(heptafluoropropyl) porphyrin [(C3F7)4PH2] macrocycles were examined. The nature and distribution of hydrocarbon oxidation products show that an autoxidation reaction pathway dominates the reaction kinetics, consistent with a radical chain process. For each catalytic system examined, PFeII species were shown not to be stable under moderate O2 pressure at 80 degrees C; in every case, the PFeII catalyst precursor was converted quantitatively to high-spin PFeIII complexes prior to the observation of any hydrocarbon oxidation products. Once catalytic isobutane oxidation is initiated, all reactions are marked by concomitant decomposition of the porphyrin-based catalyst. In situ 17O NMR spectroscopic studies confirm the incorporation of 17O from labeled water into the oxidation products, implicating the involvement of PFe-OH in the catalytic cycle. Importantly, Br8(C6F5)4PFe-based catalysts, which lack macrocycle C-H bonds, do not exhibit augmented stability with respect to analogous catalysts based on (C6F5)4PFe and (C3F7)4PFe species. The data presented are consistent with a hydrocarbon oxidation process in which PFe complexes play dual roles of radical chain initiator, and the species responsible for the catalytic decomposition of organic peroxides. This modified Haber-Weiss reaction scheme provides for the decomposition of tert-butyl hydroperoxide intermediates via reaction with PFe-OH complexes; the PFeIII species responsible for hydroperoxide decomposition are regenerated by reaction of PFeII with dioxygen under these experimental conditions.     

Photochemisch induzierte oxidative addition von aldehyden an dekacarbonyldirhenium(0)

Decacarbonyldirhenium(O) (I) reacts photochemically with acetaldehyde or propionaldehyde (II, III) to give predominantly tetradecacarbonyl-μ-hydridotrirhenium (VI). In addition, μ-acyloctacarbonyl-μ-hydridodirhenium complexes (IV, V) are obtained in oxidative addition reactions with simultaneous loss of two CO ligands. Complexes IV and V were characterized by their elemental analyses, IR, ¹H NMR, and ¹³C NMR spectra. Furthermore, the molecular structure of IV was determined by X-ray structure analysis. IV shows approximate (C_s-symmetry. Two Re(CO₄) groups are connected via the C and O atoms of the carbonyl function of an acetyl bridge, and from the steric arrangement of the Re(CO)₄ moieties and NMR spectroscopic evidence, a hydrido bridge has to be assumed between the Re atoms, which rules out a ReRe bond. The two coordination octahedrons are joined by the hydrido bridge. The connection of two further edges by the acetyl bridge causes an eclipsed arrangement of the CO ligands in IV.     

Synthesis and properties of rhodium(III) porphyrin cyclic tetramer and cofacial dimer

Rhodium(III) porphyrin complexes, [Rh(4-PyT(3)P)Cl](4) (1) and [Rh(2-PytB(3)P)Cl](2) (2) (4-PyT(3)P = 5-(4-pyridyl)-10,15,20-tritolylporphyrinato dianion, 2-PytB(3)P = 5-(2-pyridyl)-10,15,20-tri(4-tert-butyl)phenylporphyrinato dianion), were self-assembled and characterized by (1)H nuclear magnetic resonance spectroscopy, infrared spectroscopy, and electron spray ionization-mass spectroscopy methods. The spectroscopic results certified that the rhodium porphyrin complexes 1 and 2 have a cyclic tetrameric structure and a cofacial dimeric structure, respectively. The X-ray structure analysis of 1 confirmed the cyclic structure of the complex. The Soret bands of both oligomers were significantly broadened by excitonic interactions between the porphyrin units, compared to those observed for a corresponding analogue of Rh(TTP)(Py)Cl (TTP = 5,10,15,20-tetratolylporphyrinato dianion, Py = pyridine). Stepwise oxidation of the porphyrin rings in the oligomers was observed by cyclic voltammetry. The oligomers 1 and 2 are very stable in solution, and they slowly undergo reactions with pyridine to give corresponding monomer complexes only at high temperatures (approximately 80 degrees C).     

Novel mercury(II) complexes of porphyrins

Treatment of octa-alkylporphyrins (e.g. 1–3) with mercury(II) acetate in methylene chloride and tetrahydrofuran affords novel complexes (4) containing two porphyrin rings layered between three Hg atoms. A new type of stereoisomerism in regularly substituted porphyrins (e.g. 1a, 2a) is identified; it is observed by NMR spectroscopy and occurs because two forms of the complex (4) are possible, depending upon which faces of the porphyrin molecule are turned in towards the central Hg atom. The NMR spectra also indicate that in concentrated solution the double sandwich complexes (4) are stable towards disproportionation and recombination. On the basis of the inherent geometrical arrangements in the complex (4), an efficient NMR method for unambiguous identification of the four primary type isomers of the aetio- and copro-porphyrin series is described.

In very dilute solution, or in mixtures containing nucleophilic solvents such as pyridine, methanol, dioxan, or tetrahydrofuran (in the absence of excess mercury(II) acetate), the double sandwich complexes (4) are destroyed to afford normal 1:1 metalloporphyrins.     

Probing stepwise complexation in phenylazomethine dendrimers by a metallo-porphyrin core

A series of dendritic phenylazomethines (DPA), which have a meso-substituted zinc porphyrin core (DPAGX-ZnP, X = 1-4), were synthesized. Structural studies of these dendrimers were carried out using Tri-SEC (triple detection after size exclusion chromatography), intrinsic viscosity analysis, TEM (tunneling electron microscopy), and molecular modeling calculations by AM1. As a result, a sphere-like structure within a single-nanometer scale (R(h) = 22 A for DPAG4-ZnP) was observed. In addition, encapsulating effects by the DPA shell in the larger dendrimers were confirmed as fundamental properties, based on the UV-vis abosorption spectra, cyclic voltammograms, and 1H NMR spin-lattice relaxation times (T1). The DPAGX-ZnP acts as a multi-metal ion reservoir for SnCl2 and FeCl3. The generation-4 dendrimer (DPAG4-ZnP) can take up to 60 molar amounts of metal complexes around the porphyrin core. A quantitative study of the metal assembling reaction by UV-vis titration revealed stepwise layer-by-layer complexations from the inner imines nearest to the core to the surface. The redox behavior and fluorescence of the zinc porphyrin in these metal-assembled dendrimers also support the stepwise complexation of the metal ion. These analyses suggest that the finely assembled metal complexes in a dendrimer architecture strongly affect the electronic status of the porphyrin core. Results from transient absorption measurements strongly indicate a very fast electron transfer on a subpicosecond time scale between the core and assembled metal complexes.     

卵磷脂与四乙酰氧基苯基卟啉金属配合物的相互作用

本文用~(31)P.NMR和~1HNMR谱分析了卵磷脂的组分和结构,并以小角X射线散射法(SAXS)研究了所合成的六种四乙酰氧基卟啉金属配合物与卵磷脂的相互作用,发现卟啉分子镶嵌于磷脂双层的疏水链之间,使双分子层间距变大,而金属卟啉分子因其与磷脂的极性头基的静电相互作用,所形成的磷脂双分子层的间距介于纯卵磷脂和含有卟啉分子的卵磷脂所构成的双分子层之间.     

A Five‐layer π‐Aromatic Structure Formed through Self‐assembly of a Porphyrin Trimer and Two Aromatic Guests

In this study we synthesized two‐ and four‐armed porphyrins – bearing two carboxyl and four 2‐aminoquinolino functionalities, respectively, at their meso positions – as a complementary hydrogen bonding pair for the self‐assembly of a D₂‐symmetric porphyrin trimer host. Two units of the two‐armed porphyrin and one unit of the four‐armed porphyrin self‐assembled quantitatively into the D₂‐symmetric porphyrin trimer, stabilized through ammidinium‐carboxylate salt bridge formation, in CH₂Cl₂ and CHCl₃. The porphyrin trimer host gradually bound two units of 1,3,5‐trinitrobenzene between the pair of porphyrin units, forming a five‐layer aromatic structure. At temperatures below ?40 °C, the rates of association and dissociation of the complexes were slow on the NMR spectroscopic time scale, allowing the 1 : 1 and 1 : 2 complexes of the trimer host and trinitrobenzene guest(s) to be detected independently when using less than 2 eq of trinitrobenzene. Vis titration experiments revealed the values of K₁ (2.1±0.4×10⁵ M^?1) and K₂ (2.2±0.06×10⁴ M^?1) in CHCl₃ at room temperature.     

Synthesis, reactivity, and properties of N-fused porphyrin rhenium(I) tricarbonyl complexes

The thermal reactions of N-fused tetraarylporphyrins or N-confused tetraarylporphyrins with Re2(CO)10 gave the rhenium(I) tricarbonyl complexes bearing N-fused porphyrinato ligands (4) in moderate to good yields. The rhenium complexes 4 are characterized by mass, IR, 1H, and 13C NMR spectroscopy, and the structures of tetraphenylporphynato complex 4a and its nitro derivative 15 are determined by X-ray single crystal analysis. The rhenium complexes 4 show excellent stability against heat, light, acids, bases, and oxidants. The aromatic substitution reactions of 4 proceed without a loss of the center metal to give the nitro (15), formyl (16), benzoyl (17), and cyano derivatives (19), regioselectively. In the electrochemical measurements for 4, one reversible oxidation wave and two reversible reduction waves are observed. Their redox potentials imply narrow HOMO-LUMO band gaps of 4 and are consistent with their electronic absorption spectra, in which the absorption edges exceed 1000 nm. Theoretical study reveals that the HOMO and LUMO of the rhenium complexes are exclusively composed of the N-fused porphyrin skeleton. Protonation of 4 takes place at the 21-position regioselectively, reflecting the high coefficient of the C21 atom in the HOMO orbital. The skeletal rearrangement reaction from N-confused porphyrin Re(I) complex (8) to N-fused porphyrin Re(I) complex (4) is suggested from the mechanistic study as well as DFT calculations.     

Phosphorus complexes of N-fused porphyrin and its reduced derivatives: new isomers of porphyrin stabilized via coordination

N-fused isophlorin 3 and its tautomeric phlorin forms 4 and 5, the new constitutional isomers of porphyrin which preserve the basic skeleton of their maternal N-fused porphyrin, have been identified in the course of investigation of phosphorus insertion into N-fused porphyrin 2. N-fused porphyrin reacts with PCl3 in toluene yielding phosphorus(V) N-fused isophlorin 3-P wherein the macrocycle acts as a trianionic tridentate ligand. The identical product has been formed in the reaction of N-confused porphyrin 1 and POCl3 or PCl3. The coordinating environment of phosphorus(V) in 3-P as determined by X-ray crystallography resembles a distorted trigonal pyramid with the nitrogen atoms occupying equatorial positions with the oxygen atom lying at the unique apex. Phosphorus(V) is significantly displaced by 0.732(1) A from the N3 plane. The P-N distances are as follows P-N(22) 1.664(2), P-N(23) 1.645(2), and P-N(24) 1.672(2). All P-N(pyrrolic) bond lengths are markedly shorter than the P-N distances in phosphorus porphyrins. 3-P is susceptible to proton addition at the inner C(9) carbon atom, yielding aromatic 4-P. The modified macrocycle acts as a dianionic ligand and allows the efficient 18 pi-electron delocalization pathway. Two stereoisomers affording the syn (4-P syn) and anti (4-P anti) location of the H(9) atom with respect to the oxygen atom of the PO unit have been identified by (1)H NMR. A regioselective reduction of free base N-fused porphyrin 2 with NaBH4 yielded a nonaromatic isomer of 4, that is, N-fused phlorin 5 due to an addition of a hydride to the C(15) carbon and a proton to one of the pyrrolic nitrogens. The isomer 5 reacts with PCl 3 yielding phosphorus(V) fused isophlorin 3-P. Density functional theory has been applied to model the molecular and electronic structure of porphyrin isomers 3, 4, and 5 and their phosphorus(V) complexes.     

不对称希夫碱卟啉及其稀土配合物的合成与表征

以二甲基甲酰胺为溶剂,5-对氨基苯基-10,15,20-三苯基卟啉与苯甲醛直接反应得到一种不对称希夫碱卟啉化合物,并合成了它的稀土配合物.用元素分析、紫外-可见光谱、红外光谱1、H核磁共振以及X射线光电子能谱对这些化合物进行了表征,推测了稀土乙酰丙酮卟啉配合物的结构,稀土离子与乙酰丙酮的两个O原子和卟啉的4个吡咯N原子配位,配位数为6,稀土离子位于卟啉平面的上方.     

Platinum(II) complexes bearing 1,1'-bis(diphenylphosphino)ferrocene as building blocks for functionalized redox active porphyrins

Reactions of the cationic complex ions [PtMe(Me2SO)(PP)]+ (PP = dppf (1,1'-bis(diphenylphosphino)ferrocene) and dppe (1,2-bis(diphenylphosphino)ethane)) with 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin (TpyP) led to the formation of the symmetrical tetraplatinated porphyrin complexes, [PtMe(PP)]4TpyP.X4 (PP = dppf, X = CF3SO3-, 3, and PP = dppe, X = BF4-, 5) containing the organometallic fragment [PtMe(PP)]. The precursor sulfoxide platinum complexes [PtMe(Me2SO)(dppf)]CF3SO3, 2 and [PtMe(Me2SO)(dppe)]BF4, 4, were prepared by halide abstraction from [PtMeCl(dppf)], 1, and by controlled protonolysis of [PtMe2(dppe)] respectively, in the presence of a small amount of dimethyl sulfoxide. All these starting platinum(II) compounds, as well as the porphyrin derivatives 3 and 5, were fully characterized through elemental analysis, 1H NMR mono- and bidimensional, 31P[1H], 31P-1H HMBC, UV/Vis absorption and photophysical measurements. The X-ray crystal structure of complex 1 has been determined. In order to ascertain the electronic influence of ferrocene, the spectroscopic and redox properties of 3 were compared with those of TPyP and of the analogous 5. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), 1H and 31P NMR data, and UV/Vis data, all suggest a certain degree of communication between the central porphyrin and the peripheral hetero-bimetallic fragments. In contrast, no detectable interaction among these peripheral groups seem to come into play. Unlikely from the porphyrin derivative 5, formation of well defined fluorescent mesoscopic ring structures was easily achieved by simple evaporation from diluted dichloromethane solutions of 3.     

Dynamic Assembly Inclusion Complexes of Tweezer‐type Bis(zinc porphyrin) with 5,15‐Di(4‐pyridyl)porphyrin Derivatives

Dynamic assembly inclusion complexes of tweezer-type bis(zinc porphyrin) (1) with di(4-pyridyl)porphyrin derivatives have been designed and constructed. The complexes are induced by Zn-N coordination, and the weak binding allows the large-size di(4-pyridyl)porphyrin guests in random rotation. Dynamic characteristics of these assemblies, such as ligand exchange and dynamic fluorescence quenching, have been investigated by 1H NMR, UV-Vis and fluorescence spectra. The stability of such assembly has pronounced dependence on the size-matching effect and thermal effect.