Volatile Organic Compounds(VOCs)are highly harmful to human beings and other organisms,and thus the elimination of VOCs is extremely urgent.Here,La-Si co-doped TiO_(2)microsphere photocatalysts,which were prepared by ...Volatile Organic Compounds(VOCs)are highly harmful to human beings and other organisms,and thus the elimination of VOCs is extremely urgent.Here,La-Si co-doped TiO_(2)microsphere photocatalysts,which were prepared by a hydrothermal method,exhibited high photocatalytic activity in the decomposition of formaldehyde compared with TiO_(2).The improved activity can be attributed to the promoted separation efficiency and density of the charge carriers,as verified by the electrochemical results in combination with density functional theory calculations.In addition,the Si dopant changed the microstructure and surface acidity,while the addition of La promoted the separation efficiency of charge carriers.More interestingly,it was found that singlet oxygen was the key species in the activation of molecular dioxygen,and it played a pivotal role in the photocatalytic decomposition of formaldehyde.This work provides a novel strategy for the selective activation of dioxygen for use in the decomposition of formaldehyde.展开更多
The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinitie...The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.展开更多
A copper-TiO2 based catalyst（Cu-OH-Cl-TiO2） was prepared through a slurry impregnation approach and the catalyst was found to be active and selective for the epoxidation of propylene by dioxygen. With a feed gas of ...A copper-TiO2 based catalyst（Cu-OH-Cl-TiO2） was prepared through a slurry impregnation approach and the catalyst was found to be active and selective for the epoxidation of propylene by dioxygen. With a feed gas of 10% C3H6, 10% O2 and 80% N2 at a gas hourly space velocity（GHSV） of 4000 h-1, a propylene conversion of 4.8% and a propylene oxide（PO） selectivity of 38.9% were achieved over the obtained Cu-OH-Cl-TiO2 catalyst at a reaction temperature of 500 K. It revealed that Cu2＋ provided by crystalline Cu2（OH）3Cl plays a key role in catalytic conversion of propylene to PO.展开更多
The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The hi...The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.展开更多
The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with c...The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.展开更多
The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （...The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.展开更多
The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performan...The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid （PTA） were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X （X = Cl, OCH3） and Y （Y = H, CH3, Cl） groups bonded to the aromatic rings of the Co （Ⅱ） complexes were investigated.展开更多
AIM: To evaluate whether serum and tumor indoleamine 2,3-dioxygenase activities can predict lymphatic invasion (LI) or lymph node metastasis in colorectal carcinoma.METHODS: The study group consisted of 44 colorectal ...AIM: To evaluate whether serum and tumor indoleamine 2,3-dioxygenase activities can predict lymphatic invasion (LI) or lymph node metastasis in colorectal carcinoma.METHODS: The study group consisted of 44 colorectal carcinoma patients. The patients were re-grouped according to the presence or absence of LI and lymph node metastasis. Forty-three cancer-free subjects without any metabolic disturbances were included into the control group. Serum neopterin was measured by enzyme linked immunosorbent assay. Urinary neopterin and biopterin, serum tryptophan (Trp) and kynurenine (Kyn) concentrations of all patients were determined by high performance liquid chromatography. Kyn/Trp was calculated and its correlation with serum neopterin was determined to estimate the serum indoleamine 2,3-dioxygenase activity. Tissue sections from the studied tumors were re-examined histopathologically and were stained by immunohistochemistry with indoleamine-2,3-dioxygenase antibodies.RESULTS: Neither serum nor urinary neopterin was significantly different between the patient and control groups (both P > 0.05). However, colorectal carcinoma patients showed a significant positive correlation between the serum neopterin levels and Kyn/Trp (r = 0.450, P < 0.01). Urinary biopterin was significantly higher in cancer cases (P < 0.05). Serum Kyn/Trp was significantly higher in colorectal carcinoma patients (P < 0.01). Lymphatic invasion was present in 23 of 44 patients, of which only 12 patients had lymph node metastasis. Eleven patients with LI had no lymph node metastasis. Indoleamine-2,3-dioxygenase intensity score was significantly higher in LI positive cancer group (44.56% ± 6.11%) than negative colorectal cancer patients (24.04% ± 6.90%), (P < 0.05). Indoleamine 2,3-dioxygenase expression correlated both with the presence of LI and lymph node metastasis (P < 0.01 and P < 0.05, respectively). A significant difference between the accuracy of diagnosis by using either total indoleamine-2,3-dioxygenase immunostaining score or of lymph node metastasis was found during the evaluation of cancer patients.CONCLUSION: Indoleamine-2,3-dioxygenase expression may predict the presence of unrecognized LI and lymph node metastasis and may be included in the histopathological evaluation of colorectal carcinoma cases.展开更多
The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed...The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.展开更多
Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co ...Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co 2PP 8 and Co 2PP 4) in N,N dimethylformamide at room temperature. The partial pressure of dioxygen necessary for half oxygenation ( P 1/2 ) and Hill coefficient ( n ) at 298 K were determined as follows: P 1/2 =54.2 kPa, n =2.0 for Co 2PP 8 and P 1/2 =6.8 kPa, n =1.8 for Co 2PP 4,respectively. The rate equations of reversible oxygen binding by Co 2PP 8 were determined and the reaction path was proposed. The results of thermodynamic and kinetic studies indicate that there exists strong cooperative effect during oxygenation of the compounds. The ESR observation reveals that the dioxygen complexes formed in the solutions are of superoxo (Co O - 2) type.展开更多
ith an improved EHMO method, three modes (flat-lying, vertical , and in-clined insertion) for adsorption and activation of dioxygen on (100) , (110) and(111) surfaces of Na_2O and of K,O have been exaniinecl, and the ...ith an improved EHMO method, three modes (flat-lying, vertical , and in-clined insertion) for adsorption and activation of dioxygen on (100) , (110) and(111) surfaces of Na_2O and of K,O have been exaniinecl, and the interaction ofthese dioxygen adspecies with CH_4 and with CH_3 · (radical) from gas pliase liasbeen investigated. The results indicate that both oxides tend to forni less cliargedadspecies of dioxygen, with the flat-lying adsorption on (110) surface most favor-able energetically. All these cliemisorbed dioxygen species are capable of interactingeffectively with CH_4 and Abstract ing one hydrogen atom from the CH_4 molecule andtheir tendencies to reassociate with CH_3 · , which would easily lead to deep oxida-tion of the fragments of hydrocarbons, are enhanced with inereasing negativecliarges on them. In comparison with Na_2O, K_2O has a little stronger tendency tostabilize less charged dioxygen adspecies; this has a close relation with the knownexperimental fact that K￣+ showed better promoting effect than Na￣+ in improvingC_2-selectivity in methane oxidative coupling (MOC ).展开更多
An active and recyclable catalyst system, poly(maleic acid-divinyi benzene)-ruthenium complexes selectively catalyze the oxidation of styrene with dioxygen to benzaldehyde (60-70% yield) and phenyl acetaldehyde (10-3...An active and recyclable catalyst system, poly(maleic acid-divinyi benzene)-ruthenium complexes selectively catalyze the oxidation of styrene with dioxygen to benzaldehyde (60-70% yield) and phenyl acetaldehyde (10-30%yield). The polymer supports play an important role in the in-situ generation and stabization of catalytically active ruthenium species, RCOORu(IV).展开更多
A simple and convenient copper-catalyzed direct oxyphosphorylation of enamides with P（O）-H compounds and dioxygen has been developed under mild conditions. This methodology can allow the synthesis of a series of val...A simple and convenient copper-catalyzed direct oxyphosphorylation of enamides with P（O）-H compounds and dioxygen has been developed under mild conditions. This methodology can allow the synthesis of a series of valuable β-ketophosphine oxides β-ketophosphonates in moderate to good yields with a broad substrate scope simply by using readily-available starting materials.展开更多
The dinuclear complex of [Fe2L{O2P(OPh)2}](ClO4)2· Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N’, N’-tetrakis (N-ethyl-2-benzimidazolyemethyl)2-hydroxy-1, 3-diamino-propane) h...The dinuclear complex of [Fe2L{O2P(OPh)2}](ClO4)2· Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N’, N’-tetrakis (N-ethyl-2-benzimidazolyemethyl)2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P1 with cell constants a = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3)° nm, α = 94.41(3)°, β = 115.31(3)°, γ = 99.90(3)°, V = 3.267(1) nm3, z = 2, R = 0.084 7 and Rw = 0.177 8. The Fe(II) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(II) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (?60°C). The 1/O2 adduct is stable at ? 60°C but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-O) and 897 cm-1 (γO-O), and the latter is the characteristic of a μ-1,2-peroxo species, indicating that dioxygen adducts can serve as models for the putative oxygenated intermediate of some non-heme diiron-oxo proteins.展开更多
The activation of dioxygen and incorporation into hydrocarbons have been achieved under mild conditions by a methane monooxygenase (MMO)-like system using a dinuclear iron complex [Fe2Dhist(OAc)2] BPh4 ·3H2O as t...The activation of dioxygen and incorporation into hydrocarbons have been achieved under mild conditions by a methane monooxygenase (MMO)-like system using a dinuclear iron complex [Fe2Dhist(OAc)2] BPh4 ·3H2O as the model complex, zinc powder as the electron donor, HOAc as the proton source and methylviologen as the electron transfer agent. The results show that styrene is oxygenated predominantly to styrene oxide (1 396 mol/100 mol of the Fe2 complex), benzaldehyde (16160) and acetophenone (986), and cyclohexane to cyclohexanol (9370) and cyclo-hexanone (2670). EPR studies indicate that the hypervalent ironoxo spiecs FeⅣFeⅣ=O, derived from FeⅢFeⅢ core via reduction, O2-binding and protonation, is the active intermediate which inserts the activated oxygen atom into C=C or C-H bond giving each product. The system closely resembles MMO and its close relative hemerythrin in the aspects of reaction phenomena, EPR characteristics and product distributions. The Mn2 analog cmplex、 Fe-Zn het-erodinuclear complex and mononuclear iron complex show no catalytic activity, indicating that dinuclear iron core is in-despansable to catalytic activity.展开更多
A mixed-valent high spin (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex bearing N,N′-bis(5-tertbutylsalicylidene)-1,2-diaminobenzene(Salophen^(tBu)) ligand was synthesized by reacting (Salophen^(tBu))Co(Ⅱ)(Py) with O_(2) at lo...A mixed-valent high spin (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex bearing N,N′-bis(5-tertbutylsalicylidene)-1,2-diaminobenzene(Salophen^(tBu)) ligand was synthesized by reacting (Salophen^(tBu))Co(Ⅱ)(Py) with O_(2) at low temperature.This complex was isolated and structurally characterized by single crystal X-ray diffraction and infrared spectrum.Magnetic measurement showed a quartet ground state for this complex at room temperature,which was also supported by electron paramagnetic resonance (EPR)characterization.Computational investigations indicated the deviation of the equatorial N_(2)O_(2) coordination geometry around the Co(Ⅱ) center from plane stabilized the quartet state.The end-on type O_(2) adduct of this (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex was isolated as dark-brown crystals and structurally and spectroscopically characterized.EPR measurement of this compound in solid state at room temperature presented an isotropic singlet at g~2,revealing the superoxide-like electronic feature of the coordinated O_(2) and was in line with the calculation results.The reactivity of the Co(Ⅲ)-O_(2) complex with N-hydroxyphthalimide,which can act as hydrogen atom donor,was also examined.展开更多
Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized grou...Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized groups on one or two matrix molecule(s),the approaches to simply and simultaneously deposit two oxygen atoms from dioxygen into two specific C(sp^(3))positions of pure saturated hydrocarbons have rarely succeeded because they are involved in the targeted activation of three inert C–Hσbonds all at once.Here,we show that a TiO_(2)-CH_(3)CN photocatalytic suspension system enables the insertion of dioxygen into one C(sp^(3))–C(sp^(3))bond of strained cycloparaffin derivatives,by which difunctionalized hydroxyketone products are obtained in a one-pot reaction.With the cleavage event to release strain as the directional driving force,as-designed photocatalytic reaction systems show 21 examples ofβ-hydroxyketone products with 31%–76%isolated yields for three-membered ring derivatives and 5 examples ofγ-hydroxyketone products with 30%–63%isolated yields for four-membered ring substrates.^(18)O isotopic labeling experiments using^(18)O2,Ti^(18)O_(2) and intentionally added H218O,respectively,indicated that both oxygen atoms of hydroxyketone products were exclusively from dioxygen,suggesting a previously unknown H^(+)/TiO_(2)-e−catalyzed arrangement pathway of the hydroperoxide intermediate to convert dioxygen into hydroxyketone units.展开更多
A reflux-treatment of soluble polyaniline(SPA)in dimethylformamide(DMF)containing CoCl_2 yields an active catalyst for dioxygen reduction which can be adsorbed on the electrode surface firmly.The catalytic reduction o...A reflux-treatment of soluble polyaniline(SPA)in dimethylformamide(DMF)containing CoCl_2 yields an active catalyst for dioxygen reduction which can be adsorbed on the electrode surface firmly.The catalytic reduction of dioxygen at the glassy carbon(GC)electrode modified by the cata- lyst was studied with cyclic voltammetry(CV),rotating disk electrode(RDE)and rotating ring-disk electrode(RRDE).The kinetic process of dioxygen reduction at the modified electrode was analyzed with a new RRDE theory dealing with a nondiffusion-controlled process on ring electrode.The rate constants for each scheme of dioxygen reduction were calculated,showing that only 2-electron reduction to H_2O_2 was conducted at the modified electrode.The effect of solution acidity on the electrocatalytic behaviour for dioxygen reduction was investigated.A possibility of initiating catalytic activity for dioxygen reduction was explored with ESCA method.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.22076063,22076098,and 21477047)the Natural Science Foundation of Shandong Province(No.ZR2020MB033)+1 种基金the Key Laboratory of Photochemical Conversion and Optoelectronic Materials,TIPC,CAS(No.PCOM202106)the program for Taishan Scholars of Shandong Province,and the Science and Technology Programof the University of Jinan(No.XKY2111).
文摘Volatile Organic Compounds(VOCs)are highly harmful to human beings and other organisms,and thus the elimination of VOCs is extremely urgent.Here,La-Si co-doped TiO_(2)microsphere photocatalysts,which were prepared by a hydrothermal method,exhibited high photocatalytic activity in the decomposition of formaldehyde compared with TiO_(2).The improved activity can be attributed to the promoted separation efficiency and density of the charge carriers,as verified by the electrochemical results in combination with density functional theory calculations.In addition,the Si dopant changed the microstructure and surface acidity,while the addition of La promoted the separation efficiency of charge carriers.More interestingly,it was found that singlet oxygen was the key species in the activation of molecular dioxygen,and it played a pivotal role in the photocatalytic decomposition of formaldehyde.This work provides a novel strategy for the selective activation of dioxygen for use in the decomposition of formaldehyde.
文摘The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
基金This work is supported by the National Natural Science Foundation of China(Grant No.2007205).
文摘The oxygenation of cobalt (II) hydroxamates (CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined. The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.
基金Supported by the National Basic Research Program of China(No.2007CB613303)the National Natural Science Foundation of China(No.20731003)
文摘A copper-TiO2 based catalyst（Cu-OH-Cl-TiO2） was prepared through a slurry impregnation approach and the catalyst was found to be active and selective for the epoxidation of propylene by dioxygen. With a feed gas of 10% C3H6, 10% O2 and 80% N2 at a gas hourly space velocity（GHSV） of 4000 h-1, a propylene conversion of 4.8% and a propylene oxide（PO） selectivity of 38.9% were achieved over the obtained Cu-OH-Cl-TiO2 catalyst at a reaction temperature of 500 K. It revealed that Cu2＋ provided by crystalline Cu2（OH）3Cl plays a key role in catalytic conversion of propylene to PO.
文摘The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.
基金the National Natural Science Foundation of China.
文摘The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.
基金The authors gratefully acknowledge the grants from the National Natural Science Foundation of China(No.20072025)Education 0ffice Foundation of Sichuan Province(No.2005C012)Sichuan Provincial Department of Science&Technology(No.2006J13-143)in support of this work.
文摘The oxygenation constants （Ko2） of cobalt（Ⅱ） hydroxamates （CoL^1 2-CoL^3 2） with benzo-15-crown-5 （B15C5） pendants were measured over the range of -5 to ＋20 ℃, and the values of thermodynamic parameters （ΔH^0 and ΔS^0） were calculated based on these （Ko2） values, Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL^4 2.
基金supported by the National Natural Science Foundation of China(No.2007205).
文摘The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid （PTA） were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X （X = Cl, OCH3） and Y （Y = H, CH3, Cl） groups bonded to the aromatic rings of the Co （Ⅱ） complexes were investigated.
基金Supported by Gazi UniversityScientific Research Projects DivisionNo.01/2007-62
文摘AIM: To evaluate whether serum and tumor indoleamine 2,3-dioxygenase activities can predict lymphatic invasion (LI) or lymph node metastasis in colorectal carcinoma.METHODS: The study group consisted of 44 colorectal carcinoma patients. The patients were re-grouped according to the presence or absence of LI and lymph node metastasis. Forty-three cancer-free subjects without any metabolic disturbances were included into the control group. Serum neopterin was measured by enzyme linked immunosorbent assay. Urinary neopterin and biopterin, serum tryptophan (Trp) and kynurenine (Kyn) concentrations of all patients were determined by high performance liquid chromatography. Kyn/Trp was calculated and its correlation with serum neopterin was determined to estimate the serum indoleamine 2,3-dioxygenase activity. Tissue sections from the studied tumors were re-examined histopathologically and were stained by immunohistochemistry with indoleamine-2,3-dioxygenase antibodies.RESULTS: Neither serum nor urinary neopterin was significantly different between the patient and control groups (both P > 0.05). However, colorectal carcinoma patients showed a significant positive correlation between the serum neopterin levels and Kyn/Trp (r = 0.450, P < 0.01). Urinary biopterin was significantly higher in cancer cases (P < 0.05). Serum Kyn/Trp was significantly higher in colorectal carcinoma patients (P < 0.01). Lymphatic invasion was present in 23 of 44 patients, of which only 12 patients had lymph node metastasis. Eleven patients with LI had no lymph node metastasis. Indoleamine-2,3-dioxygenase intensity score was significantly higher in LI positive cancer group (44.56% ± 6.11%) than negative colorectal cancer patients (24.04% ± 6.90%), (P < 0.05). Indoleamine 2,3-dioxygenase expression correlated both with the presence of LI and lymph node metastasis (P < 0.01 and P < 0.05, respectively). A significant difference between the accuracy of diagnosis by using either total indoleamine-2,3-dioxygenase immunostaining score or of lymph node metastasis was found during the evaluation of cancer patients.CONCLUSION: Indoleamine-2,3-dioxygenase expression may predict the presence of unrecognized LI and lymph node metastasis and may be included in the histopathological evaluation of colorectal carcinoma cases.
文摘The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.
文摘Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co 2PP 8 and Co 2PP 4) in N,N dimethylformamide at room temperature. The partial pressure of dioxygen necessary for half oxygenation ( P 1/2 ) and Hill coefficient ( n ) at 298 K were determined as follows: P 1/2 =54.2 kPa, n =2.0 for Co 2PP 8 and P 1/2 =6.8 kPa, n =1.8 for Co 2PP 4,respectively. The rate equations of reversible oxygen binding by Co 2PP 8 were determined and the reaction path was proposed. The results of thermodynamic and kinetic studies indicate that there exists strong cooperative effect during oxygenation of the compounds. The ESR observation reveals that the dioxygen complexes formed in the solutions are of superoxo (Co O - 2) type.
文摘ith an improved EHMO method, three modes (flat-lying, vertical , and in-clined insertion) for adsorption and activation of dioxygen on (100) , (110) and(111) surfaces of Na_2O and of K,O have been exaniinecl, and the interaction ofthese dioxygen adspecies with CH_4 and with CH_3 · (radical) from gas pliase liasbeen investigated. The results indicate that both oxides tend to forni less cliargedadspecies of dioxygen, with the flat-lying adsorption on (110) surface most favor-able energetically. All these cliemisorbed dioxygen species are capable of interactingeffectively with CH_4 and Abstract ing one hydrogen atom from the CH_4 molecule andtheir tendencies to reassociate with CH_3 · , which would easily lead to deep oxida-tion of the fragments of hydrocarbons, are enhanced with inereasing negativecliarges on them. In comparison with Na_2O, K_2O has a little stronger tendency tostabilize less charged dioxygen adspecies; this has a close relation with the knownexperimental fact that K￣+ showed better promoting effect than Na￣+ in improvingC_2-selectivity in methane oxidative coupling (MOC ).
文摘An active and recyclable catalyst system, poly(maleic acid-divinyi benzene)-ruthenium complexes selectively catalyze the oxidation of styrene with dioxygen to benzaldehyde (60-70% yield) and phenyl acetaldehyde (10-30%yield). The polymer supports play an important role in the in-situ generation and stabization of catalytically active ruthenium species, RCOORu(IV).
基金We gratefully acknowledge financial support from the National Natural Science Foundation of China （Nos. 21572217, 21402184, 21172213, and 21302109）.
文摘A simple and convenient copper-catalyzed direct oxyphosphorylation of enamides with P（O）-H compounds and dioxygen has been developed under mild conditions. This methodology can allow the synthesis of a series of valuable β-ketophosphine oxides β-ketophosphonates in moderate to good yields with a broad substrate scope simply by using readily-available starting materials.
文摘The dinuclear complex of [Fe2L{O2P(OPh)2}](ClO4)2· Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N’, N’-tetrakis (N-ethyl-2-benzimidazolyemethyl)2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P1 with cell constants a = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3)° nm, α = 94.41(3)°, β = 115.31(3)°, γ = 99.90(3)°, V = 3.267(1) nm3, z = 2, R = 0.084 7 and Rw = 0.177 8. The Fe(II) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(II) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (?60°C). The 1/O2 adduct is stable at ? 60°C but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-O) and 897 cm-1 (γO-O), and the latter is the characteristic of a μ-1,2-peroxo species, indicating that dioxygen adducts can serve as models for the putative oxygenated intermediate of some non-heme diiron-oxo proteins.
文摘The activation of dioxygen and incorporation into hydrocarbons have been achieved under mild conditions by a methane monooxygenase (MMO)-like system using a dinuclear iron complex [Fe2Dhist(OAc)2] BPh4 ·3H2O as the model complex, zinc powder as the electron donor, HOAc as the proton source and methylviologen as the electron transfer agent. The results show that styrene is oxygenated predominantly to styrene oxide (1 396 mol/100 mol of the Fe2 complex), benzaldehyde (16160) and acetophenone (986), and cyclohexane to cyclohexanol (9370) and cyclo-hexanone (2670). EPR studies indicate that the hypervalent ironoxo spiecs FeⅣFeⅣ=O, derived from FeⅢFeⅢ core via reduction, O2-binding and protonation, is the active intermediate which inserts the activated oxygen atom into C=C or C-H bond giving each product. The system closely resembles MMO and its close relative hemerythrin in the aspects of reaction phenomena, EPR characteristics and product distributions. The Mn2 analog cmplex、 Fe-Zn het-erodinuclear complex and mononuclear iron complex show no catalytic activity, indicating that dinuclear iron core is in-despansable to catalytic activity.
基金the National Natural Science Foundation of China(21988101,21801044,22071122,U19B6002)Shanghai Sailing Program(18YF1401800)。
文摘A mixed-valent high spin (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex bearing N,N′-bis(5-tertbutylsalicylidene)-1,2-diaminobenzene(Salophen^(tBu)) ligand was synthesized by reacting (Salophen^(tBu))Co(Ⅱ)(Py) with O_(2) at low temperature.This complex was isolated and structurally characterized by single crystal X-ray diffraction and infrared spectrum.Magnetic measurement showed a quartet ground state for this complex at room temperature,which was also supported by electron paramagnetic resonance (EPR)characterization.Computational investigations indicated the deviation of the equatorial N_(2)O_(2) coordination geometry around the Co(Ⅱ) center from plane stabilized the quartet state.The end-on type O_(2) adduct of this (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex was isolated as dark-brown crystals and structurally and spectroscopically characterized.EPR measurement of this compound in solid state at room temperature presented an isotropic singlet at g~2,revealing the superoxide-like electronic feature of the coordinated O_(2) and was in line with the calculation results.The reactivity of the Co(Ⅲ)-O_(2) complex with N-hydroxyphthalimide,which can act as hydrogen atom donor,was also examined.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB36000000)the National Natural Science Foundation of China(21590811,21777167,21827809)and the National Key R&D Program of China(2018YFA0209302).
文摘Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized groups on one or two matrix molecule(s),the approaches to simply and simultaneously deposit two oxygen atoms from dioxygen into two specific C(sp^(3))positions of pure saturated hydrocarbons have rarely succeeded because they are involved in the targeted activation of three inert C–Hσbonds all at once.Here,we show that a TiO_(2)-CH_(3)CN photocatalytic suspension system enables the insertion of dioxygen into one C(sp^(3))–C(sp^(3))bond of strained cycloparaffin derivatives,by which difunctionalized hydroxyketone products are obtained in a one-pot reaction.With the cleavage event to release strain as the directional driving force,as-designed photocatalytic reaction systems show 21 examples ofβ-hydroxyketone products with 31%–76%isolated yields for three-membered ring derivatives and 5 examples ofγ-hydroxyketone products with 30%–63%isolated yields for four-membered ring substrates.^(18)O isotopic labeling experiments using^(18)O2,Ti^(18)O_(2) and intentionally added H218O,respectively,indicated that both oxygen atoms of hydroxyketone products were exclusively from dioxygen,suggesting a previously unknown H^(+)/TiO_(2)-e−catalyzed arrangement pathway of the hydroperoxide intermediate to convert dioxygen into hydroxyketone units.
文摘A reflux-treatment of soluble polyaniline(SPA)in dimethylformamide(DMF)containing CoCl_2 yields an active catalyst for dioxygen reduction which can be adsorbed on the electrode surface firmly.The catalytic reduction of dioxygen at the glassy carbon(GC)electrode modified by the cata- lyst was studied with cyclic voltammetry(CV),rotating disk electrode(RDE)and rotating ring-disk electrode(RRDE).The kinetic process of dioxygen reduction at the modified electrode was analyzed with a new RRDE theory dealing with a nondiffusion-controlled process on ring electrode.The rate constants for each scheme of dioxygen reduction were calculated,showing that only 2-electron reduction to H_2O_2 was conducted at the modified electrode.The effect of solution acidity on the electrocatalytic behaviour for dioxygen reduction was investigated.A possibility of initiating catalytic activity for dioxygen reduction was explored with ESCA method.
