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1.
Intramolecular Oxidative O‐Demethylation of an Oxoferryl Porphyrin Complexed with a Per‐O‐methylated β‐Cyclodextrin Dimer
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The intramolecular oxidation of ROCH3 to ROCH2OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met‐hemoCD3) with cumene hydroperoxide in aqueous solution. Met‐hemoCD3 is composed of meso‐tetrakis(4‐sulfonatophenyl)porphinatoiron(III) (FeIIITPPS) and a per‐O‐methylated β‐cyclodextrin dimer having an ‐OCH2PyCH2O‐ linker (Py=pyridine‐3,5‐diyl). The O=FeIVTPPS complex was formed by the reaction of met‐hemoCD3 with cumene hydroperoxide, and isolated by gel‐filtration chromatography. Although the isolated O=FeIVTPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to FeIITPPS (t1/2=7.6 h). This conversion was accompanied by oxidative O‐demethylation of an OCH3 group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=FeIVTPPS from ROCH3 yields HO‐FeIIITPPS and ROCH2.. This was followed by radical coupling to afford FeIITPPS and ROCH2OH. The hemiacetal (ROCH2OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two‐electron oxidation. 相似文献
2.
Prof. Dr. Koji Kano Toshiro Ochi Sayuri Okunaka Yusuke Ota Keiichi Karasugi Takunori Ueda Dr. Hiroaki Kitagishi 《化学:亚洲杂志》2011,6(11):2946-2955
Poly(acrylic acid) (PAA) is modified by 5‐(4‐β‐alanylaminophenyl)‐10,15,20‐tris(4‐sulfonatophenyl) porphinatoiron(III) to yield iron porphyrin‐bearing PAAs (FeP(n)s) through a condensation reaction. FeP(n)s were further functionalized by Py3CD, which is a per‐O‐methylated β‐cyclodextrin (CD) dimer with a pyridine linker and includes the porphyrin pendants to form ferric hemoCD‐P(n)s. Ferrous hemoCD‐P(3), having three porphyrin chromophores in a polymer chain, is shown to bind molecular oxygen (P1/2=7.9±1.4 Torr) in aqueous solution at pH 7.0 and 25 °C, affording oxy‐hemoCD‐P(3). Oxy‐hemoCD‐P(3) is biphasically autoxidized to ferric hemoCD‐P(3), with 27 % of the dioxygen adducts being rapidly oxidized. The rate of autoxidation of oxy‐hemoCD‐P(15), having 15 porphyrin chromophores in a polymer chain, was much faster than that of oxy‐hemoCD‐P(3), thus suggesting self‐catalyzed autoxidation of oxy‐hemoCD‐P(n)s. Oxy‐hemoCD‐P(n)s are markedly stabilized by catalase, thereby indicating that hydrogen peroxide generated from oxy‐hemoCD‐P(n) accelerates the autoxidation. Most of the hemoCD‐P(3) molecules injected into the femoral vein of a rat remained in the body, though about 16 % of the hemoCD‐P(3) molecules were excreted in the urine as a carbon monoxide adduct. 相似文献
3.
Gold nanoparticles (AuNPs) prepared by citrate reduction of aurochloric acid (HAuCl4) were functionalized by tris(4‐sulfonatophenyl)porphinatoiron(III) (FeIIIP2) and poly(ethylene glycol) with thiolated arms (PEG‐SH). FeIIIP2 on the AuNP surface existed as its μ‐oxo dimer, which was reduced by Na2S2O4 to yield monomeric FeIIP2. FeIIP2‐bearing AuNPs were further functionalized through inclusion of two sulfonatophenyl groups of FeIIP2 by a per‐O‐methylated β‐cyclodextrin dimer with a pyridine linker (Py3CD) to obtain AuNPs capable of carrying diatomic molecules in the body. The resulting AuNPs (hemoCD‐AuNPs) bound O2 as well as CO in an aqueous solution. Although a noncolloidal 1:1 complex of 5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphinatoiron(II) and Py3CD injected into the femoral vein of a rat was rapidly excreted in the urine, no excretion was observed with ferric hemoCD‐AuNPs, which were gradually accumulated in the spleen and liver of a rat. These results suggest that hemoCD‐AuNPs can be used as a carrier of diatomic molecules such as O2 and CO in vivo. 相似文献
4.
Koji Kano 《Colloid and polymer science》2008,286(1):79-84
This mini-review reports supramolecular system composed of O-methylated β-cyclodextrins and metalloporphyrins that mimic the
functions of myoglobin (Mb) in aqueous solution. Although many Mb functional models have been demonstrated so far, most models
can bind dioxygen only in organic solvents such as toluene. Recently, we prepared the model systems composed of O-methylated
β-cyclodextrin dimers having pyridine and imidazole linkers and tetrakis(4-sulfonatophenyl)porphinato iron(II) (hemoCD and
Fe(II)PImCD). HemoCD binds dioxygen reversibly in aqueous solution, and the dioxygen adduct of hemoCD is very stable (a half-lifetime
is 30 h at pH 7). Although the dioxygen affinity of Fe(II)PImCD is much higher than hemoCD, the stability and the reversibility
of this system is lower. This review compares the functions of these model systems with those in biological systems.
This review was written to dedicate to Professor Janos H. Fendler on the occasion of his 70th birthday. He gave me a chance
to study biomimetic chemistry when he was a professor of Texas A&M University. 相似文献
5.
Yongfeng Yang Tao Li Yanmei Chen 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(10):903-907
The title compound, poly[[diaqua‐1κ2O‐tetrakis(μ3‐pyridine‐2,3‐dicarboxylato)‐2:1:2′κ10N,O2:O2′,O3:O3′;2:1:2′κ8O3:O3′:N,O2‐diiron(III)strontium(II)] dihydrate], {[Fe2Sr(C7H3O4)4(H2O)2]·2H2O}n, which has triclinic (P) symmetry, was prepared by the reaction of pyridine‐2,3‐dicarboxylic acid, SrCl2·6H2O and Fe(OAc)2(OH) (OAc is acetate) in the presence of imidazole in water at 363 K. In the crystal structure, the pyridine‐2,3‐dicarboxylate (pydc2−) ligand exhibits μ3‐η1,η1:η1:η1 and μ3‐η1,η1:η1,η1:η1 coordination modes, bridging two FeIII cations and one SrII cation. The SrII cation, which is located on an inversion centre, is eight‐coordinated by six O atoms of four pydc2− ligands and two water molecules. The coordination geometry of the SrII cation can be best described as distorted dodecahedral. The FeIII cation is six‐coordinated by O and N atoms of four pydc2− ligands in a slightly distorted octahedral geometry. Each FeIII cation bridges two neighbouring FeIII cations to form a one‐dimensional [Fe2(pydc)4]n chain. The chains are connected by SrII cations to form a three‐dimensional framework. The topology type of this framework is tfj . The structure displays O—H...O and C—H...O hydrogen bonding. 相似文献
6.
Exploring the Strength of the H‐Bond in Synthetic Models for Heme Proteins: The Importance of the N−H Acidity of the Distal Base
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Dr. Mariza N. Alberti Dr. Yevhen Polyhach Dr. Manolis D. Tzirakis Laura Tödtli Prof. Dr. Gunnar Jeschke Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10194-10202
The distal hydrogen bond (H‐bond) in dioxygen‐binding proteins is crucial for the discrimination of O2 with respect to CO or NO. We report the preparation and characterization of a series of ZnII porphyrins, with one of three meso‐phenyl rings bearing both an alkyl‐tethered proximal imidazole ligand and a heterocyclic distal H‐bond donor connected by a rigid acetylene spacer. Previously, we had validated the corresponding CoII complexes as synthetic model systems for dioxygen‐binding heme proteins and demonstrated the structural requirements for proper distal H‐bonding to CoII‐bound dioxygen. Here, we systematically vary the H‐bond donor ability of the distal heterocycles, as predicted based on pKa values. The H‐bond in the dioxygen adducts of the CoII porphyrins was directly measured by Q‐band Davies‐ENDOR spectroscopy. It was shown that the strength of the hyperfine coupling between the dioxygen radical and the distal H‐atom increases with enhanced acidity of the H‐bond donor. 相似文献
7.
Dr. Suman Maji Dr. Jason C.‐M. Lee Yu‐Jhang Lu Dr. Chang‐Li Chen Mu‐Cheng Hung Dr. Peter P.‐Y. Chen Prof. Steve S.‐F. Yu Prof. Sunney I. Chan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(13):3955-3968
The dioxygen activation of a series of CuICuICuI complexes based on the ligands ( L ) 3,3′‐(1,4‐diazepane‐ 1,4‐diyl)bis(1‐{[2‐(dimethylamino)ethyl](methyl)amino}propan‐2‐ol) ( 7‐Me ) or 3,3′‐(1,4‐diazepane‐1,4‐diyl)bis(1‐{[2‐(diethylamino)ethyl](ethyl)amino}propan‐2‐ol) ( 7‐Et ) forms an intermediate capable of mediating facile O‐atom transfer to simple organic substrates at room temperature. To elucidate the dioxygen chemistry, we have examined the reactions of 7‐Me , 7‐Et , and 3,3′‐(1,4‐diazepane‐1,4‐diyl)bis[1‐(4‐methylpiperazin‐1‐yl)propan‐2‐ol] ( 7‐N‐Meppz ) with dioxygen at ?80, ?55, and ?35 °C in propionitrile (EtCN) by UV‐visible, 77 K EPR, and X‐ray absorption spectroscopy, and 7‐N‐Meppz and 7‐Me with dioxygen at room temperature in acetonitrile (MeCN) by diode array spectrophotometry. At both ?80 and ?55 °C, the mixing of the starting [CuICuICuI( L )]1+ complex ( 1 ) with O2‐saturated propionitrile (EtCN) led to a bright green solution consisting of two paramagnetic species: the green dioxygen adduct [CuIICuII(μ‐η2:η2‐peroxo)CuII( L )]2+ ( 2 ) and the blue [CuIICuII(μ‐O)CuII( L )]2+ species ( 3 ). These observations are consistent with the initial formation of [CuIICuII(μ‐O)2CuIII( L )]1+ ( 4 ), followed by rapid abortion of this highly reactive species by intercluster electron transfer from a second molecule of complex 1 to give the blue species 3 and subsequent oxygenation of the partially oxidized [CuIICuICuI( L )]2+ ( 5 ) to form the green dioxygen adduct 2 . Assignment of 2 to [CuIICuII(μ‐η2:η2‐peroxo)CuII( L )]2+ is consistent with its reactivity with water to give H2O2 and the blue species 3 , as well as its propensity to be photoreduced in the X‐ray beam during X‐ray absorption experiments at room temperature. In light of these observations, the development of an oxidation catalyst based on the tricopper system requires consideration of the following design criteria: 1) rapid dioxygen chemistry; 2) facile O‐atom transfer from the activated cluster to substrate; and 3) a suitable reductant to rapidly regenerate complex 1 to accomplish efficient catalytic turnover. 相似文献
8.
Heterotrimetallic Coordination Polymers: {CuIILnIIIFeIII} Chains and {NiIILnIIIFeIII} Layers: Synthesis,Crystal Structures,and Magnetic Properties
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Dr. Maria‐Gabriela Alexandru Dr. Diana Visinescu Prof. Marius Andruh Dr. Nadia Marino Dr. Donatella Armentano Dr. Joan Cano Prof. Francesc Lloret Prof. Miguel Julve 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5429-5446
The use of the [FeIII(AA)(CN)4]? complex anion as metalloligand towards the preformed [CuII(valpn)LnIII]3+ or [NiII(valpn)LnIII]3+ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H2valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[CuII(valpn)LnIII(H2O)3(μ‐NC)2FeIII(phen)(CN)2 {(μ‐NC)FeIII(phen)(CN)3}]NO3 ? 7 H2O}n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3] ? NO3 ? H2O ? CH3CN ( 4 ) were obtained with the [CuII(valpn)LnIII]3+ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[NiII(valpn)LnIII(ONO2)2(H2O)(μ‐NC)3FeIII(bipy)(CN)] ? 2 H2O ? 2 CH3CN}n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [NiII(valpn)LnIII]3+ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3]+, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {FeIII(bipy)(CN)4} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {NiII(valpn)LnIII} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the CuII?LnIII ( 1 – 3 ) and NiII?LnIII ( 5 – 7 ) units, as well as through the single cyanide bridge between the FeIII and either NiII ( 5 – 7 ) or CuII ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor (τo) and energy barrier (Ea) through the Arrhenius equation being 2.0×10?12 s and 29.1 cm?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (NiII–DyIII) and single cyanide (FeIII–NiII) pathways are masked by the depopulation of the Stark levels of the DyIII ion, this feature most likely accounting for the continuous decrease of χM T upon cooling observed for this last compound. 相似文献
9.
The amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H2 L ) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [FeII(H2 L )3](ClO4)2·0.6MeOH·0.9H2O a 1:1 mixture of mer and fac isomers is present whereas [FeII(H2 L )3](BF4)2·MeOH·H2O, [CoII(H2 L )3](ClO4)2·2H2O and [NiII(H2 L )3](ClO4)2·MeOH·H2O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [FeII(H2 L )3]2+ complex core to exist in the low‐spin state, whereas the [CoII(H2 L )3]2+ complex core resides in its high‐spin state, even at very low temperatures. 相似文献
10.
Olsson E Martinez A Teigen K Jensen VR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(13):3746-3758
The first part of the catalytic cycle of the pterin‐dependent, dioxygen‐using nonheme‐iron aromatic amino acid hydroxylases, leading to the FeIV?O hydroxylating intermediate, has been investigated by means of density functional theory. The starting structure in the present investigation is the water‐free Fe? O2 complex cluster model that represents the catalytically competent form of the enzymes. A model for this structure was obtained in a previous study of water‐ligand dissociation from the hexacoordinate model complex of the X‐ray crystal structure of the catalytic domain of phenylalanine hydroxylase in complex with the cofactor (6R)‐L ‐erythro‐5,6,7,8‐tetrahydrobiopterin (BH4) (PAH‐FeII‐BH4). The O? O bond rupture and two‐electron oxidation of the cofactor are found to take place via a Fe‐O‐O‐BH4 bridge structure that is formed in consecutive radical reactions involving a superoxide ion, O2?. The overall effective free‐energy barrier to formation of the FeIV?O species is calculated to be 13.9 kcal mol?1, less than 2 kcal mol?1 lower than that derived from experiment. The rate‐limiting step is associated with a one‐electron transfer from the cofactor to dioxygen, whereas the spin inversion needed to arrive at the quintet state in which the O? O bond cleavage is finalized, essentially proceeds without activation. 相似文献
11.
Single crystals of the FeII metal‐organic framework (MOF) with 1,3,5‐benzenetricarboxylate (BTC) as a linker were solvothermally obtained under air‐free conditions. X‐ray diffraction analysis of the crystals demonstrated a structure for FeII‐MOF analogous to that of [Cu3(BTC)2] (HKUST‐1). Unlike HKUST‐1, however, the FeII‐MOF did not retain permanent porosity after exchange of guest molecules. The Mössbauer spectrum of the FeII‐MOF was recorded at 80 K in zero field yielding an apparent quadrupole splitting of ΔEQ = 2.43 mm · s–1, and an isomer shift of δ = 1.20 mm · s–1, consistent with high‐spin central iron(II) atoms. Air exposure of the FeII‐MOF was found to result in oxidation of the metal atoms to afford FeIII. These results demonstrate that FeII‐based MOFs can be prepared in similar fashion to the [Cu3(BTC)2], but that they lack permanent porosity when degassed. 相似文献
12.
Observation of a CuII2(μ‐1,2‐peroxo)/CuIII2(μ‐oxo)2 Equilibrium and its Implications for Copper–Dioxygen Reactivity
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Dr. Matthew T. Kieber‐Emmons Jake W. Ginsbach Dr. Patrick K. Wick Dr. Heather R. Lucas Dr. Matthew E. Helton Dr. Baldo Lucchese Prof. Masatatsu Suzuki Prof. Andreas D. Zuberbühler Prof. Kenneth D. Karlin Prof. Edward I. Solomon 《Angewandte Chemie (International ed. in English)》2014,53(19):4935-4939
Synthesis of small‐molecule Cu2O2 adducts has provided insight into the related biological systems and their reactivity patterns including the interconversion of the CuII2(μ‐η2:η2‐peroxo) and CuIII2(μ‐oxo)2 isomers. In this study, absorption spectroscopy, kinetics, and resonance Raman data show that the oxygenated product of [(BQPA)CuI]+ initially yields an “end‐on peroxo” species, that subsequently converts to the thermodynamically more stable “bis‐μ‐oxo” isomer (Keq=3.2 at ?90 °C). Calibration of density functional theory calculations to these experimental data suggest that the electrophilic reactivity previously ascribed to end‐on peroxo species is in fact a result of an accessible bis‐μ‐oxo isomer, an electrophilic Cu2O2 isomer in contrast to the nucleophilic reactivity of binuclear CuII end‐on peroxo species. This study is the first report of the interconversion of an end‐on peroxo to bis‐μ‐oxo species in transition metal‐dioxygen chemistry. 相似文献
13.
Dr. Claire Deville Sandeep K. Padamati Dr. Jonas Sundberg Prof. Dr. Vickie McKee Prof. Dr. Wesley R. Browne Prof. Dr. Christine J. McKenzie 《Angewandte Chemie (International ed. in English)》2016,55(2):545-549
A MnII complex, [Mn(dpeo)2]2+ (dpeo=1,2‐di(pyridin‐2‐yl)ethanone oxime), activates O2, with ensuing stepwise oxidation of the methylene group in the ligands providing an alkoxide and ultimately a ketone group. X‐ray crystal‐structure analysis of an intermediate homoleptic alkoxide MnIII complex shows tridentate binding of the ligand via the two pyridyl groups and the newly installed alkoxide moiety, with the oxime group no longer coordinated. The structure of a MnII complex of the final ketone ligand, cis‐[MnBr2(hidpe)2] (hidpe=2‐(hydroxyimino)‐1,2‐di(pyridine‐2‐yl)ethanone) shows that bidentate oxime/pyridine coordination has been resumed. H218O and 18O2 labeling experiments suggest that the inserted O atoms originate from two different O2 molecules. The progress of the oxygenation was monitored through changes in the resonance‐enhanced Raman bands of the oxime unit. 相似文献
14.
Qing‐Biao Hou Li‐Juan Chen Jing Guo Shen Lin 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(3):302-305
A novel neutral polymer, {[Co2(C7H3NO4)2(H2O)4]·2H2O}n, was hydrothermally synthesized using pyridine‐2,5‐dicarboxylate (2,5‐PDC2−) as the organic linker. It features a two‐dimensional layer structure constructed from one‐dimensional {[Co(2,5‐PDC)2]2−}n chains interlinked by [Co(H2O)4]+ units. The two CoII cations occupy special positions, sitting on inversion centres. Each 2,5‐PDC2− anion chelates to one CoII cation via the pyridine N atom and an O atom of the adjacent carboxylate group, and links to two other CoII cations in a bridging mode via the O atoms of the other carboxylate group. In this way, the 2,5‐PDC2− ligand connects three neighbouring CoII centres to form a two‐dimensional network. The two‐dimensional undulating layers are linked by extensive hydrogen bonds to form a three‐dimensional supramolecular structure, with the uncoordinated solvent molecules occupying the interlamellar region. 相似文献
15.
Marc Ostermeier Dipl.‐Chem. Marie‐Anne Berlin Dipl.‐Chem. Robert M. Meudtner Dr. Serhiy Demeshko Dr. Franc Meyer Prof. Dr. Christian Limberg Prof. Dr. Stefan Hecht Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10202-10213
2,6‐Bis(1,2,3‐triazol‐4‐yl)pyridine (btp) ligands with substitution patterns ranging from strongly electron‐donating to strongly electron‐accepting groups, readily prepared by means of Cu‐catalyzed 1,3‐dipolar cycloaddition (the “click” reaction), were investigated with regard to their complexation behavior, and the properties of the resulting transition‐metal compounds were compared. Metal–btp complexes of 1:1 stoichiometry, that is, [Ru(btp)Cl2(dmso)] and [Zn(btp)Br2], could be isolated and were crystallographically characterized: they display octahedral and trigonal‐bipyramidal coordination geometries, respectively, and exhibit high aggregation tendencies due to efficient π–π stacking leading to low solubilities. Metal–btp complexes of 1:2 stoichiometry, that is, [Fe(btp)2]2+ and [Ru(btp)2]2+, could also be synthesized and their metal centers show the expected octahedral coordination spheres. The iron compounds exhibit quite a complex magnetic behavior in the solid state including spin crossover near room temperature, and hysteresis and locking into high‐spin states on tempering at 400 K, depending on the substituents on the btp ligands. Cyclic voltammetry studies of [Ru(btp)2]2+ reveal strong modulation of the oxidation potentials by more than 0.6 V and a clear linear correlation to the Hammett constant (σpara) of the substituent at the pyridine core. Isothermal titration calorimetry was used to measure the thermodynamics of the FeII–btp complexation process and enabled accurate determination of the complexation enthalpies, which display a linear relationship with the σpara values for the terminal phenyl substituents. Detailed NMR spectroscopic studies finally revealed that in the case of FeII complexation, dynamics are rapid for all investigated btp derivatives in acetonitrile, while replacing FeII by RuII or changing the solvent to dichloromethane effectively slows down ligand exchange. The results nicely demonstrate the utility of substituent parameters, originally developed for linear free‐energy relationships to explain reactivity in organic reactions, in coordination chemistry, and to illustrate the potential to custom‐design btp ligands and complexes thereof with predictable properties. The fast equilibration of the [Fe(btp)2]2+ complexes together with their tunable stability and interesting magnetic properties should enable the design of dynamic metallosupramolecular materials with advantageous properties. 相似文献
16.
Syntheses,Crystal Structures,and Luminescent Properties of ZnII/CdII Coordination Polymers with Different Interpenetrating Networks
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Jie Du 《无机化学与普通化学杂志》2015,641(5):962-966
ZnII and CdII coordination polymers with dicarboxylate and imidazole‐containing ligands, namely, [Cd (2,3‐PDC)(L)]n ( 1 ) and {[Zn(3,4‐PDC) (L)0.5] · H2O}n ( 2 ), [2,3‐H2PDC = 2,3‐pyridine dicarboxylate, 3,4‐H2PDC = 3,4‐pyridine dicarboxylate, and L = 1,4‐bis(2‐methylimidazol‐3‐ium‐1‐yl)biphenyl], were prepared and characterized by elemental analysis, IR spectroscopy, and X‐ray diffraction. Complex 1 shows a three‐dimensional (3D) structure with threefold interpenetrating diamond topology. Complex 2 features a 3D framework with twofold interpenetrating dmc topology. Moreover, the luminescent properties of complexes 1 and 2 were also investigated. 相似文献
17.
Koji Yamamoto Riku Nameki Hiromitsu Sogawa Toshikazu Takata 《Angewandte Chemie (International ed. in English)》2020,59(41):18023-18028
A dinuclear PdII complex possessing a cyclic ligand was developed as a novel doubly threaded [3]rotaxane scaffold and applied as a rotaxane cross‐linker reagent. The dinuclear complex (PdMC)2 was prepared by one‐step macrocyclization followed by the double palladation reaction. 1H NMR analysis and UV/Vis measurements revealed the formation of a doubly threaded pseudo[3]rotaxane by the complexation of (PdMC)2 with 2 equivalents of 2,6‐disubstituted pyridine 3 through double metal coordination. The treatment of (PdMC)2 with 2 equivalents of 4‐vinylpyridine (VP) afforded a doubly threaded [3]rotaxane cross‐linker (PdMC‐VP)2 . Radical co‐polymerization of VP and t‐butylstyrene in the presence of (PdMC‐VP)2 afforded a stable rotaxane cross‐linked polymer (RCP). An elastic RCP was also prepared by using n‐butyl acrylate as a monomer. The obtained RCPs exhibited higher swelling ability and higher mechanical toughness compared with the corresponding covalent cross‐linked polymers. 相似文献
18.
Three new iron(II)‐benzilate complexes [(N4Py)FeII(benzilate)]ClO4 ( 1 ), [(N4PyMe2)FeII(benzilate)]ClO4 ( 2 ) and [(N4PyMe4)FeII(benzilate)]ClO4 ( 3 ) of neutral pentadentate nitrogen donor ligands have been isolated and characterized to study their dioxygen reactivity. Single‐crystal X‐ray structures reveal a mononuclear six‐coordinate iron(II) center in each case, where benzilate binds to the iron center in monodentate mode via one carboxylate oxygen. Introduction of methyl groups in the 6‐positions of the pyridine rings makes the N4PyMe2 and N4PyMe4 ligand fields weaker compared to that of the parent N4Py ligand. All the complexes ( 1 – 3 ) react with dioxygen to decarboxylate the coordinated benzilate to benzophenone quantitatively. The decarboxylation is faster for the complex of the more sterically hindered ligand and follows the order 3 > 2 > 1 . The complexes display oxygen atom transfer reactivity to thioanisole and also exhibit hydrogen atom transfer reactions with substrates containing weak C?H bonds. Based on interception studies with external substrates, labelling experiments and Hammett analysis, a nucleophilic iron(II)‐hydroperoxo species is proposed to form upon two‐electron reductive activation of dioxygen by each iron(II)‐benzilate complex. The nucleophilic oxidants are converted to the corresponding electrophilic iron(IV)‐oxo oxidant upon treatment with a protic acid. The high‐spin iron(II)‐benzilate complex with the weakest ligand field results in the formation of a more reactive iron‐oxygen oxidant. 相似文献
19.
Jinhu Wei Liangliang Wu Hai‐Xu Wang Xiting Zhang Chun‐Wai Tse Cong‐Ying Zhou Jie‐Sheng Huang Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2020,59(38):16561-16571
Reliable methods for enantioselective cis‐dihydroxylation of trisubstituted alkenes are scarce. The iron(II) complex cis‐α‐[FeII(2‐Me2‐BQPN)(OTf)2], which bears a tetradentate N4 ligand (Me2‐BQPN=(R,R)‐N,N′‐dimethyl‐N,N′‐bis(2‐methylquinolin‐8‐yl)‐1,2‐diphenylethane‐1,2‐diamine), was prepared and characterized. With this complex as the catalyst, a broad range of trisubstituted electron‐deficient alkenes were efficiently oxidized to chiral cis‐diols in yields of up to 98 % and up to 99.9 % ee when using hydrogen peroxide (H2O2) as oxidant under mild conditions. Experimental studies (including 18O‐labeling, ESI‐MS, NMR, EPR, and UV/Vis analyses) and DFT calculations were performed to gain mechanistic insight, which suggested possible involvement of a chiral cis‐FeV(O)2 reaction intermediate as an active oxidant. This cis‐[FeII(chiral N4 ligand)]2+/H2O2 method could be a viable green alternative/complement to the existing OsO4‐based methods for asymmetric alkene dihydroxylation reactions. 相似文献
20.
Roxanne Bercy Dr. Jean-Noël Rebilly Dr. Christian Herrero Dr. Régis Guillot Hélène Maisonneuve Prof. Frédéric Banse 《欧洲无机化学杂志》2023,26(34):e202300236
Three new amine/pyridine FeII complexes bearing pentadentate ligand with one, two or three electron enriched 4-methoxy-3,5-dimethylpyridine were used as catalysts for the oxidation of small organic molecules by hydrogen peroxide. The distribution of products formed suggests that these ligands are not enough electron donating to promote the O−O heterolytic cleavage of the oxidant in order to generate selective FeV(O) species. Using acetic acid in the reaction mixtures results in a significant increase of the efficiency of these catalytic systems. Our investigations show that the use of AcOH leads to the protonation/dissociation of a pyridyl moiety and the formation of (N4)FeII(OAc)(OH) species. These complexes readily react with excess hydrogen peroxide to yield (N4)FeIII(OAc)(OOH) intermediates. These latter intermediates are proposed to evolve into (N4)FeIV(OAc)(O), which are more efficient than the usual (N4)FeIV(O) and (N5)FeIV(O). 相似文献