Electron transfer reactions between O-benzoyl t-butylhydroxyl- amine,t-BuNHOCOPh(1)and perfluorodiacyl peroxides(RfCO_2)_2(2)may serve as a novel method for generating useful t-hutyl perfluoroalkyl nitroxldes at room ...Electron transfer reactions between O-benzoyl t-butylhydroxyl- amine,t-BuNHOCOPh(1)and perfluorodiacyl peroxides(RfCO_2)_2(2)may serve as a novel method for generating useful t-hutyl perfluoroalkyl nitroxldes at room temperature in CFCl2-CF2Cl.展开更多
Five-membered pyrroline nitroxides with high-potential is fascinating as catholyte for aqueous organic redox flow batteries(AORFBs),however,it suffers from a primary deficiency of insufficient stability due to ring-op...Five-membered pyrroline nitroxides with high-potential is fascinating as catholyte for aqueous organic redox flow batteries(AORFBs),however,it suffers from a primary deficiency of insufficient stability due to ring-opening side reaction.Herein we report a spatial structure regulation strategy by host-vip chemistry,encapsulating 3-carbamoyl-2,2,5,5-tetramethylpyrroline-1-oxyl(CPL)into hydrosoluble cyclodextrins(CDs)with an inclusion structure of N–O⋅head towards cavity bottom,to boost the solubility and cyclability of pyrroline nitroxides significantly.The armor-clad CPL(CPL⊂HP-β-CD)catholyte in 0.05–0.5 M presents a battery capacity fade rate as low as 0.002%/cycle(0.233%/day)compared to the sole CPL in 0.05 M(0.039%/cycle or 5.23%/day)over 500 cycles in assembled AORFBs.The optimized reclining spatial structure with N–O⋅head towards CD cavity bottom effectively inhibits the attack of Lewis base species on the hydrogen abstraction site in pyrroline ring,and thus avoids the ring-opening side reaction of pyrroline nitroxides.展开更多
Studies on the protective action of glutathione (1) via the destruction of free radicals in biological system are of great significance. The authors have previously reported the reaction of glutathione with 2,2, 6,6-t...Studies on the protective action of glutathione (1) via the destruction of free radicals in biological system are of great significance. The authors have previously reported the reaction of glutathione with 2,2, 6,6-tetramethyl-4-hydroxypiperidine-1-展开更多
A new cobalt(Ⅱ)-radical complex:[Co(im4-py)_(2)(PNB)_(2)](im4-py=2-(4'-pyridyl)-4,4,5,5-tetramethylimidazole-1-oxyl,HPNB=p-nitrobenzoic acid)has been synthesized and characterized by X-ray diffraction analysis,el...A new cobalt(Ⅱ)-radical complex:[Co(im4-py)_(2)(PNB)_(2)](im4-py=2-(4'-pyridyl)-4,4,5,5-tetramethylimidazole-1-oxyl,HPNB=p-nitrobenzoic acid)has been synthesized and characterized by X-ray diffraction analysis,elemental analysis,IR,and magnetic properties.X-ray diffraction analysis shows that the complex exists as mononuclear molecules and Co(Ⅱ)ion is four-coordinated with two radicals and two PNB-ligands.The magnetic susceptibility study indicates the complex exhibits weak ferromagnetic interactions between cobalt(Ⅱ)and im4-py radical.The magnetic property is explained by the magnetic and structure exchange mechanism.CCDC:976028.展开更多
Nitrogen hyperfine splitting constants (aN values) of seven symmetrically para-disubstituted diphenyl nitroxides (1-Y's) were measured by EPR and used in conjunction with five literature values in our correlation ...Nitrogen hyperfine splitting constants (aN values) of seven symmetrically para-disubstituted diphenyl nitroxides (1-Y's) were measured by EPR and used in conjunction with five literature values in our correlation analysis. The correlation of these ON values by single-parameter Eq. 1 and dual-parameter Eq. 2 shows that the application of Eq. 2 does not significantly improve the correlation. But our data can also be interpreted by the proposition that the spin-delocalization effect is not completely nonexistent and that it might have revealed itself through the aN values of two very weakly polar substituents with pronounced spin-stabilizing abilities, i.e., SMe and SiMe3.展开更多
The kinetics of reduction of nitroxides including 4-hydroxy-TEMPO, 4-methoxy-TEMPOand 4-hexanoyloxy-TEMPO, which are of different lipophilicities, by vitamin C in cationic,non-ionic and anionic micelles, i. e. CTAB, T...The kinetics of reduction of nitroxides including 4-hydroxy-TEMPO, 4-methoxy-TEMPOand 4-hexanoyloxy-TEMPO, which are of different lipophilicities, by vitamin C in cationic,non-ionic and anionic micelles, i. e. CTAB, Triton X-100 and SDS, respectively, have beenstudied by ESR spectroscopy by a stopped-flow technique. A mechanism for the reactionconducted in micelles is proposed and the rate constants for the elementary reactions areevaluated. It is found that the rates of single electron transfer reactions involving the ni-troxides are dependent on the nature of the micelle and the lipophilicity of the nitroxide.The rates are increased in CTAB, decreased in SDS, whereas unaffected in Triton X-100.And the greater the lipophilicity of the nitroxide, the more pronounced the rate variation.As high as a 3600-fold increase in the rate was observed for 4-hexanoyloxy-TEMPO in CTABover that in SDS. The micellar effects are rationalized on the basis of analysis of parame-ters and line shape of the ESR spectra for the nitroxides in the micelles.展开更多
Crystal structures of new nitronyl nitroxide derivatives 1, 2 and 3 were determined with X-ray diffraction analysis: 1, monoclinic, C-2/c, a = 1.204 (5) nm; b = 0.9730 (5) nm, c = 2.7049 (10) nm, beta = 98.189 (15)deg...Crystal structures of new nitronyl nitroxide derivatives 1, 2 and 3 were determined with X-ray diffraction analysis: 1, monoclinic, C-2/c, a = 1.204 (5) nm; b = 0.9730 (5) nm, c = 2.7049 (10) nm, beta = 98.189 (15)degrees, V = 3.2315 (24) nm(3), Z = 8; 2, orthorhombic, Pbca, a = 0.61262(2) nm, b = 1.11426(6) nm, c = 2.30543(13) nm, V = 1.57373(13) nm(3), Z = 4; 3, monoclinic, P2(1)/n, a = 0.64253(4) nm, b = 2.55003(17) nm, c = 1.15497(6) nm, beta = 95.000(3)degrees, V = 1.8852(2) nm(3), Z = 4. Their magnetic properties were measured with SQUID and analyzed based on their crystal structures with simple singlet-triplet, modified one dimensional antiferromagnetic chain and modified singlet-triplet models respectively: 1, J/k(b) = -2.5 K; 2, J/k(b) = 7.8 K, theta = 2.8 K; 3, J/k(b) = -0.96 K, theta = 0.21 K.展开更多
Stable s-butyl n-heptafluorobutyryl nitroxide 3 has been generated in an electron transfer reaction in F113 ( CFCl2CF2Cl ) solution at r.t. The aN values for 3 in 11 aprotic solvents show a linear correlation with cy...Stable s-butyl n-heptafluorobutyryl nitroxide 3 has been generated in an electron transfer reaction in F113 ( CFCl2CF2Cl ) solution at r.t. The aN values for 3 in 11 aprotic solvents show a linear correlation with cybotactic solvent parameters ET and Z. The physical significance for slopes, slope×ET or slope×Z, and the extrapolated intercepts on the aN axis are well established. The plots of aN versus noncybotactic solvent parameters, such as dipolar moment and dielectric constant, are badly behaved.展开更多
The electron spin resonance spectra of N-carbamoyl-N-(l-oxyl-2,2,5,5-tetramethyl-pyrrolin-3-yl) urea compounds in ten solvents with different polarities were determined. It was found that the hyperfine splitting const...The electron spin resonance spectra of N-carbamoyl-N-(l-oxyl-2,2,5,5-tetramethyl-pyrrolin-3-yl) urea compounds in ten solvents with different polarities were determined. It was found that the hyperfine splitting constant AN and spin density pN. as well as the energy difference between two adjacent energy levels E of different pyrroline nitroxides in the same solvent increase with the increase of electron-withdrawing α-bility of the substituted groups on the aromatic ring. There was a linear correlation between AN and Reichardt ET value, and between AN and Z value as well. Such a linear correlation was also found between solvent viscosity n and ESR rotational correlation time r. On the other hand, the correlation between T and the relative height hr of peak on high field was reverse. The results are discussed in the paper.展开更多
The halogen and hydrogen bonding complexes and trihalomethanes （CHX3, X=C1, Br, I） are between 2,2,6,6-tetramethylpiperidine-noxyl simulated by computational quantum chem- istry. The molecular electrostatic potentia...The halogen and hydrogen bonding complexes and trihalomethanes （CHX3, X=C1, Br, I） are between 2,2,6,6-tetramethylpiperidine-noxyl simulated by computational quantum chem- istry. The molecular electrostatic potentials, geometrical parameters and interaction energy of halogen and hydrogen bonding complexes combined with natural bond orbital analysis are obtained. The results indicate that both halogen and hydrogen bonding interactions obey the order CI〈Br〈I, and hydrogen bonding is stronger than the corresponding halogen bond- ing. So, hydrogen bonding complexes should be dominant in trihalomethanes. However, it is possible that halogen bonding complex is competitive, even preponderant, in triiodomethane due to the similar interaction energy. This work might provide useful information on specific solvent effects as well as for understanding the mechanism of nitroxide radicals as a bioprobe to interact with the halogenated compounds in biological and biochemical fields.展开更多
Three new lanthanide-nitronyl nitroxide radical complexes were successfully synthesized with the formula of [Ln（hfac）3（PyNONIT）2]（Ln=Dy（1）, Tm（2）, Ho（3））. All the complexes were isostructural and crystalli...Three new lanthanide-nitronyl nitroxide radical complexes were successfully synthesized with the formula of [Ln（hfac）3（PyNONIT）2]（Ln=Dy（1）, Tm（2）, Ho（3））. All the complexes were isostructural and crystallized in C2/c space group, in which the central metal ions were eight-coordinated in slightly distorted square antiprism coordination geometries（D4d symmetry）. Magnetic studies indicated the existence of antiferromagnetic interaction in complexes 1–3.展开更多
A new binuclear Cu（Ⅱ） complex with nitronyl nitroxide radicals [Cu（NIT3Py）2Cl2]2（NIT3Py = 2-（3＇-pyridinyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been synthesized and structurally characterized b...A new binuclear Cu（Ⅱ） complex with nitronyl nitroxide radicals [Cu（NIT3Py）2Cl2]2（NIT3Py = 2-（3＇-pyridinyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been synthesized and structurally characterized by X-ray diffraction analysis.It crystallizes in monoclinic,space group C2/c with a = 38.483（4）,b = 7.2450（8）,c = 27.559（3） ,β = 134.0180（10）°,V = 5525.6（10） 3,C48H64Cl4Cu2N12O8,Mr = 1206.00,Z = 4,Dc = 1.450 g/cm3,μ（MoKα） = 1.025 mm-1,F（000） = 2504,S = 1.066,the final R = 0.0471 and wR = 0.1121 for 3286 observed reflections（I 2σ（I））.The title complex consists of centrosymmetric dinuclear units [Cu（NIT3Py）2Cl2]2,in which the copper ions are square-pyramidally coordinated by two pyridyl nitrogen atoms of two radical ligands and three chlorine anions,two of which bridge the copper ions.The magnetic measurements show ferromagnetic interactions between the copper ions and the radical ligands.展开更多
Two new tri-spin radical-Ln（III）-radical complexes, [Ln（hfac）3（NITPh-Ph）2] （Ln = Dy （1） and Tb （2）, NITPh-Ph = 4＇-biphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and hfac = hexafluoroacetylacetonat...Two new tri-spin radical-Ln（III）-radical complexes, [Ln（hfac）3（NITPh-Ph）2] （Ln = Dy （1） and Tb （2）, NITPh-Ph = 4＇-biphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and hfac = hexafluoroacetylacetonate） have been synthesized and characterized by X-ray diffraction analysis, elemental analysis, IR, Uv-visible and magnetic properties. X-ray analysis reveals that the two complexes are isomorphous and crystallize in the triclinic system, space group P1. For complex 1, a = 12.402（3）, b = 15.414（3）, c = 17.383（3） A, a = 68.61（3）, β = 81.97（3）, y = 79.40（3）°, V = 3031.7（11） A3, Z = 2, Mr = 1401.86, Dc = 1.536 g/cm^3, kt = 1.344 mm^-1, F（000） = 1398, the final GOF = 1.173, R = 0.0670 and wR = 0.1376 for 9035 observed reflections with 1 〉 2a（/）; while for complex 2, a = 12.397（3）, b = 15.391（3）, c = 17.395（4） A, a = 68.62（3）, fl = 81.97（3）, ）, = 79.60（3）°, V = 3030.0（11） A3, Z = 2, Mr = 1398.29, Dc = 1.537 g/cm^3,μ = 1.344 mm-1, F（000） = 1398, the final GOF = 1.130, R = 0.0644 and wR = 0.1382 for 8989 observed reflections with 1 〉 2a（/）. They all consist of the discrete adducts, in which the central Ln（lll） ions are coordinated by six oxygen atoms from three hfacs and two oxygen atoms from nitronyl radicals. The temperature dependency of magnetic susceptibilities for these two complexes is studied, showing that the magnetic interactions are governed by the depopulation of the Ln Stark levels.展开更多
A new complex, [Ni（acac）2（NITQ）2]-2CH2C12 1 （acac = acetylacetone, NITQ = 2-（2＂-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide）, was synthesized and charac- terized by elemental analysis, IR spec...A new complex, [Ni（acac）2（NITQ）2]-2CH2C12 1 （acac = acetylacetone, NITQ = 2-（2＂-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide）, was synthesized and charac- terized by elemental analysis, IR spectroscopy, UV-Vis absorption spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 9.6970（19）, b = 20.410（4）, c = 12.166（2） A, β = 93.89（3）°, Mr = 997.43, V= 2402.3（8） A3, Z = 2, Dc = 1.379 g/cm3, F（000） = 1040,μ = 0.684 mm-1, the final R = 0.0423 and wR = 0.1197 for 2884 observed reflections （1 〉 2σ（I））. Compound 1 is found to assume a mononuclear structure, which is further linked into a three-dimensional （3D） supramolecular network by hydrogen-bonding, C1...O weak contact and π...π stacking interactions. Moreover, the luminescent properties of the ligand and compound 1 were further investigated in detail.展开更多
A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal...A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal structure was determined by X-ray diffraction method. The complex crystallizes in monoclinic, space group P21/n with a = 9.913(4), b = 19.057(8), c = 10.169(4) ? b = 114.292(7), V = 1751(1) 3, C26H38Cu2N8O14, Mr = 813.72, Dc = 1.543 g/cm3, m(MoKa) = 1.290 mm-1, F(000) = 840, Z = 2, the final R = 0.0398 and wR = 0.0986 for 1878 observed reflections (I>2s(I)). The imino nitroxide 2-(2-pyridyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl (im2-py) is reduced in the reaction to yield Him2-py which consists of oxalato-bridged centrosymmetric [Cu2(m-C2O4)(Him2-py)2(H2O)2]2+ ions and noncoordinated NO3- anions. Each copper(II) ion is in a distorted tetragonal pyramid environment: two nitrogen atoms from Him2-py and two oxygen atoms from the oxalate group are in the basal plane, and one water molecule at the axial position.展开更多
A new complex of formula [Co(nitmpy)2(tp)(H2O)2]n (nitmpy = 2-(3-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and tp = terephthalato dianion) has been synthesized and structurally characterized. The complex...A new complex of formula [Co(nitmpy)2(tp)(H2O)2]n (nitmpy = 2-(3-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and tp = terephthalato dianion) has been synthesized and structurally characterized. The complex crystallizes in monoclinic, space group P21/n with a = 10.647(3), b = 11.093(3), c = 16.647(5) ? b = 106.185(6), V = 1888.2(10) 3, C32H40CoN6O10, Mr = 727.63, Dc = 1.280 g/cm3, m(MoKa) = 0.513 mm-1, F(000) = 762, Z = 2, the final R = 0.0549 and wR = 0.1265 for 1753 observed reflections (I > 2s(I)). The crystal structure consists of neutral infinite chains where the Co(nitmpy)2(H2O)2 units are linked by terephthalate ligands, and the 1-D chains develop into two-dimensional network via the hydrogen bond interactions.展开更多
A new complex [Zn（NIT-1′-MeBzlm）Cl2（H2O）] （NIT-1′-MeBzlm = 2-{2′-[（1′- methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been prepared and structurally characterized by X-ray diffr...A new complex [Zn（NIT-1′-MeBzlm）Cl2（H2O）] （NIT-1′-MeBzlm = 2-{2′-[（1′- methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been prepared and structurally characterized by X-ray diffraction method. Crystal data： monoclinic, space group P21/n, Z = 4, C15H21Cl2N4O3Zn, Mr = 441.63, a = 7.2225（10）, b = 30.849（4）, c = 8.8758（13）A, β = 103.904（2）°, V = 1919.6（5）A^3, Dc = 1.528 g/cm^3, μ（MoKα） = 1.579 mm^-1, F（000） = 908, R = 0.0436 and wR = 0.1029 for 2456 observed reflections with I〉 2σ（I）. X-ray analysis reveals that the Zn（Ⅱ） ion is four-coordinated with a distorted tetrahedron. There also exist H-bonds, π-π piling interactions and weak intermolecular contacts between the NO groups which form a mutual stagger 3-D network configuration. Magnetic investigation reveals that there exists intermolecular antiferro- and ferromagnetic interactions in the title complex.展开更多
A new one-dimensional dicyanamide bridged zinc（Ⅱ） complex containing nitronyl nitroxide radicals [Zn（NO3）（NIT-1′-MeBzIm）（dca）]n·（H2O）n （NIT-1′-MeBzIm = 2-{2′-[（1′-methyl）benzimidazolyl]}-4,4,5,5...A new one-dimensional dicyanamide bridged zinc（Ⅱ） complex containing nitronyl nitroxide radicals [Zn（NO3）（NIT-1′-MeBzIm）（dca）]n·（H2O）n （NIT-1′-MeBzIm = 2-{2′-[（1′-methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, dca = dicyanamide anion） has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P^-1, with a = 7.428（3）, b = 9.839（3）, c = 16.708（6） A^°, α = 93.270（4）, β = 101.642（4）,γ= 100.632（4）°, C17.5H21N8O5.5Zn, Mr = 496.79, V = 1169.7（7） A^°^3, Dc = 1.411 g/cm^3, μ（MoKα） - 1.096 mm^-1, Z = 2, F（000） = 512, R = 0.0583 and wR = 0.1663 for 4295 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that the zinc（Ⅱ） ion is six-coordinated with a distorted octahedral geometry. These units develop as 1D species where dicyanamide ligands bridge zine（ID ions. In addition, molecules are linked by π-π piling interactions to form 1-D double-chains. Magnetic investigation indicates that the weak intramolecular interactions are antiferromagnetic with J = -0.27 cm^-1, where the spin Hamitonian is defined as H = -2∑ijJijSiS within the complex.展开更多
A novel azide-bridged copper（Ⅱ） coordination polymer, [Cu3（NITpPy）4（N3）6]n （NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazline-3-oxide-1-oxyl）, was structurally and magnetically characterized. It crystallizes i...A novel azide-bridged copper（Ⅱ） coordination polymer, [Cu3（NITpPy）4（N3）6]n （NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazline-3-oxide-1-oxyl）, was structurally and magnetically characterized. It crystallizes in the triclinic space group P with a = 7.6932（10）, b = 14.5556（19）, c = 16.122（2） , α = 108.443（2）, β = 95.251（2）, γ = 104.236（2）°, V = 1631.7（4） 3, C48H64Cu3N30O8, Mr = 1379.87, Z = 1, Dc = 1.404 g/cm3, μ（MoKα） = 1.041 mm-1, F（000） = 713, the R = 0.0510 and wR = 0.1185 for 4285 observed reflections with I 2σ（I）. X-ray analysis reveals that the Cu（Ⅱ） ions are linked by nitrogen atom of μ1,1 azido ligands to form a Cu-Cu-Cu unit. The units are linked by μ1,3 azido ligands through a bridging style to form a one-dimensional coordination polymer. The variable-temperature magnetic susceptibility data of the complex show ferromagnetic interactions in the complex.展开更多
A new oxalato-bridged dinickel（Ⅱ） complex [Ni2（NIT-MeImz）4（C2O4）]（Ac）2·8H2O has been synthesized and characterized structurally as well as magnetically.It crystallizes in monoclinic,space group C2/c with...A new oxalato-bridged dinickel（Ⅱ） complex [Ni2（NIT-MeImz）4（C2O4）]（Ac）2·8H2O has been synthesized and characterized structurally as well as magnetically.It crystallizes in monoclinic,space group C2/c with a=24.608（4）,b=21.399（3）,c=17.992（3）,β=131.680（2）°,V=7076（2）3,C50H86N16Ni2O24,Mr=1412.77,Z=4,Dc=1.326 g/cm3,μ（MoKα）=0.614 mm-1,F（000）=2984,R=0.0751 and wR=0.1791 for 2956 observed reflections with Ⅰ＆gt;2σ（Ⅰ）.X-ray analysis reveals that the crystal structure consists of [Ni2（NIT-MeImz）4（C2O4）]2＋ moiety and two Ac^- anions. Each nickel（H） ion is six-coordinated with a distorted octahedral geometry： two nitrogen atoms and two oxygen atoms from NIT-Melmz together with two other oxygen atoms from the oxalato ion. The 2-D net structure is formed and arranged through intermolecular H-bonding interactions. Magnetic measurements show antiferromagnetic interactions for this complex.展开更多
文摘Electron transfer reactions between O-benzoyl t-butylhydroxyl- amine,t-BuNHOCOPh(1)and perfluorodiacyl peroxides(RfCO_2)_2(2)may serve as a novel method for generating useful t-hutyl perfluoroalkyl nitroxldes at room temperature in CFCl2-CF2Cl.
基金supported by grants from the National Natural Science Foundation of China(No.21875181,22209130,and 22279100)the Natural Science Basic Research Program of Shaanxi(No.2019JLP-13)the China Postdoctoral Science Foundation(No.2022M722524)。
文摘Five-membered pyrroline nitroxides with high-potential is fascinating as catholyte for aqueous organic redox flow batteries(AORFBs),however,it suffers from a primary deficiency of insufficient stability due to ring-opening side reaction.Herein we report a spatial structure regulation strategy by host-vip chemistry,encapsulating 3-carbamoyl-2,2,5,5-tetramethylpyrroline-1-oxyl(CPL)into hydrosoluble cyclodextrins(CDs)with an inclusion structure of N–O⋅head towards cavity bottom,to boost the solubility and cyclability of pyrroline nitroxides significantly.The armor-clad CPL(CPL⊂HP-β-CD)catholyte in 0.05–0.5 M presents a battery capacity fade rate as low as 0.002%/cycle(0.233%/day)compared to the sole CPL in 0.05 M(0.039%/cycle or 5.23%/day)over 500 cycles in assembled AORFBs.The optimized reclining spatial structure with N–O⋅head towards CD cavity bottom effectively inhibits the attack of Lewis base species on the hydrogen abstraction site in pyrroline ring,and thus avoids the ring-opening side reaction of pyrroline nitroxides.
文摘Studies on the protective action of glutathione (1) via the destruction of free radicals in biological system are of great significance. The authors have previously reported the reaction of glutathione with 2,2, 6,6-tetramethyl-4-hydroxypiperidine-1-
文摘A new cobalt(Ⅱ)-radical complex:[Co(im4-py)_(2)(PNB)_(2)](im4-py=2-(4'-pyridyl)-4,4,5,5-tetramethylimidazole-1-oxyl,HPNB=p-nitrobenzoic acid)has been synthesized and characterized by X-ray diffraction analysis,elemental analysis,IR,and magnetic properties.X-ray diffraction analysis shows that the complex exists as mononuclear molecules and Co(Ⅱ)ion is four-coordinated with two radicals and two PNB-ligands.The magnetic susceptibility study indicates the complex exhibits weak ferromagnetic interactions between cobalt(Ⅱ)and im4-py radical.The magnetic property is explained by the magnetic and structure exchange mechanism.CCDC:976028.
基金Project supported by the National Natural Science Foundation of China.
文摘Nitrogen hyperfine splitting constants (aN values) of seven symmetrically para-disubstituted diphenyl nitroxides (1-Y's) were measured by EPR and used in conjunction with five literature values in our correlation analysis. The correlation of these ON values by single-parameter Eq. 1 and dual-parameter Eq. 2 shows that the application of Eq. 2 does not significantly improve the correlation. But our data can also be interpreted by the proposition that the spin-delocalization effect is not completely nonexistent and that it might have revealed itself through the aN values of two very weakly polar substituents with pronounced spin-stabilizing abilities, i.e., SMe and SiMe3.
基金the National Natural Science Foundation of China.
文摘The kinetics of reduction of nitroxides including 4-hydroxy-TEMPO, 4-methoxy-TEMPOand 4-hexanoyloxy-TEMPO, which are of different lipophilicities, by vitamin C in cationic,non-ionic and anionic micelles, i. e. CTAB, Triton X-100 and SDS, respectively, have beenstudied by ESR spectroscopy by a stopped-flow technique. A mechanism for the reactionconducted in micelles is proposed and the rate constants for the elementary reactions areevaluated. It is found that the rates of single electron transfer reactions involving the ni-troxides are dependent on the nature of the micelle and the lipophilicity of the nitroxide.The rates are increased in CTAB, decreased in SDS, whereas unaffected in Triton X-100.And the greater the lipophilicity of the nitroxide, the more pronounced the rate variation.As high as a 3600-fold increase in the rate was observed for 4-hexanoyloxy-TEMPO in CTABover that in SDS. The micellar effects are rationalized on the basis of analysis of parame-ters and line shape of the ESR spectra for the nitroxides in the micelles.
文摘Crystal structures of new nitronyl nitroxide derivatives 1, 2 and 3 were determined with X-ray diffraction analysis: 1, monoclinic, C-2/c, a = 1.204 (5) nm; b = 0.9730 (5) nm, c = 2.7049 (10) nm, beta = 98.189 (15)degrees, V = 3.2315 (24) nm(3), Z = 8; 2, orthorhombic, Pbca, a = 0.61262(2) nm, b = 1.11426(6) nm, c = 2.30543(13) nm, V = 1.57373(13) nm(3), Z = 4; 3, monoclinic, P2(1)/n, a = 0.64253(4) nm, b = 2.55003(17) nm, c = 1.15497(6) nm, beta = 95.000(3)degrees, V = 1.8852(2) nm(3), Z = 4. Their magnetic properties were measured with SQUID and analyzed based on their crystal structures with simple singlet-triplet, modified one dimensional antiferromagnetic chain and modified singlet-triplet models respectively: 1, J/k(b) = -2.5 K; 2, J/k(b) = 7.8 K, theta = 2.8 K; 3, J/k(b) = -0.96 K, theta = 0.21 K.
文摘Stable s-butyl n-heptafluorobutyryl nitroxide 3 has been generated in an electron transfer reaction in F113 ( CFCl2CF2Cl ) solution at r.t. The aN values for 3 in 11 aprotic solvents show a linear correlation with cybotactic solvent parameters ET and Z. The physical significance for slopes, slope×ET or slope×Z, and the extrapolated intercepts on the aN axis are well established. The plots of aN versus noncybotactic solvent parameters, such as dipolar moment and dielectric constant, are badly behaved.
文摘The electron spin resonance spectra of N-carbamoyl-N-(l-oxyl-2,2,5,5-tetramethyl-pyrrolin-3-yl) urea compounds in ten solvents with different polarities were determined. It was found that the hyperfine splitting constant AN and spin density pN. as well as the energy difference between two adjacent energy levels E of different pyrroline nitroxides in the same solvent increase with the increase of electron-withdrawing α-bility of the substituted groups on the aromatic ring. There was a linear correlation between AN and Reichardt ET value, and between AN and Z value as well. Such a linear correlation was also found between solvent viscosity n and ESR rotational correlation time r. On the other hand, the correlation between T and the relative height hr of peak on high field was reverse. The results are discussed in the paper.
基金This work is supported by the National Natural Science Foundation of China （No.20675009 and No.90922023） and the Research Fund for the Doctoral Program of Higher Education of China （No.273914）.
文摘The halogen and hydrogen bonding complexes and trihalomethanes （CHX3, X=C1, Br, I） are between 2,2,6,6-tetramethylpiperidine-noxyl simulated by computational quantum chem- istry. The molecular electrostatic potentials, geometrical parameters and interaction energy of halogen and hydrogen bonding complexes combined with natural bond orbital analysis are obtained. The results indicate that both halogen and hydrogen bonding interactions obey the order CI〈Br〈I, and hydrogen bonding is stronger than the corresponding halogen bond- ing. So, hydrogen bonding complexes should be dominant in trihalomethanes. However, it is possible that halogen bonding complex is competitive, even preponderant, in triiodomethane due to the similar interaction energy. This work might provide useful information on specific solvent effects as well as for understanding the mechanism of nitroxide radicals as a bioprobe to interact with the halogenated compounds in biological and biochemical fields.
基金Project supported by the National Natural Science Foundation of China(21421001)the Ministry of Education of China(ITR13022,13R30)
文摘Three new lanthanide-nitronyl nitroxide radical complexes were successfully synthesized with the formula of [Ln（hfac）3（PyNONIT）2]（Ln=Dy（1）, Tm（2）, Ho（3））. All the complexes were isostructural and crystallized in C2/c space group, in which the central metal ions were eight-coordinated in slightly distorted square antiprism coordination geometries（D4d symmetry）. Magnetic studies indicated the existence of antiferromagnetic interaction in complexes 1–3.
基金supported by the National Natural Science Foundation of China (No. 20901059)the Technological Development Foundation Project of Tianjin Educational Committee (No. 20080503)
文摘A new binuclear Cu（Ⅱ） complex with nitronyl nitroxide radicals [Cu（NIT3Py）2Cl2]2（NIT3Py = 2-（3＇-pyridinyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been synthesized and structurally characterized by X-ray diffraction analysis.It crystallizes in monoclinic,space group C2/c with a = 38.483（4）,b = 7.2450（8）,c = 27.559（3） ,β = 134.0180（10）°,V = 5525.6（10） 3,C48H64Cl4Cu2N12O8,Mr = 1206.00,Z = 4,Dc = 1.450 g/cm3,μ（MoKα） = 1.025 mm-1,F（000） = 2504,S = 1.066,the final R = 0.0471 and wR = 0.1121 for 3286 observed reflections（I 2σ（I））.The title complex consists of centrosymmetric dinuclear units [Cu（NIT3Py）2Cl2]2,in which the copper ions are square-pyramidally coordinated by two pyridyl nitrogen atoms of two radical ligands and three chlorine anions,two of which bridge the copper ions.The magnetic measurements show ferromagnetic interactions between the copper ions and the radical ligands.
基金Supported by the Natural Science Foundation of Anhui Province (KJ2012B174)the Doctoral Start-up Fund of Huainan Normal University
文摘Two new tri-spin radical-Ln（III）-radical complexes, [Ln（hfac）3（NITPh-Ph）2] （Ln = Dy （1） and Tb （2）, NITPh-Ph = 4＇-biphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and hfac = hexafluoroacetylacetonate） have been synthesized and characterized by X-ray diffraction analysis, elemental analysis, IR, Uv-visible and magnetic properties. X-ray analysis reveals that the two complexes are isomorphous and crystallize in the triclinic system, space group P1. For complex 1, a = 12.402（3）, b = 15.414（3）, c = 17.383（3） A, a = 68.61（3）, β = 81.97（3）, y = 79.40（3）°, V = 3031.7（11） A3, Z = 2, Mr = 1401.86, Dc = 1.536 g/cm^3, kt = 1.344 mm^-1, F（000） = 1398, the final GOF = 1.173, R = 0.0670 and wR = 0.1376 for 9035 observed reflections with 1 〉 2a（/）; while for complex 2, a = 12.397（3）, b = 15.391（3）, c = 17.395（4） A, a = 68.62（3）, fl = 81.97（3）, ）, = 79.60（3）°, V = 3030.0（11） A3, Z = 2, Mr = 1398.29, Dc = 1.537 g/cm^3,μ = 1.344 mm-1, F（000） = 1398, the final GOF = 1.130, R = 0.0644 and wR = 0.1382 for 8989 observed reflections with 1 〉 2a（/）. They all consist of the discrete adducts, in which the central Ln（lll） ions are coordinated by six oxygen atoms from three hfacs and two oxygen atoms from nitronyl radicals. The temperature dependency of magnetic susceptibilities for these two complexes is studied, showing that the magnetic interactions are governed by the depopulation of the Ln Stark levels.
基金Supported by the National Natural Science Foundation of China(No.21071006)the Natural Science Foundation of Henan Province(No.102102210457)the Natural Science Foundation of the Henan Higher Education Institutions of China(No.2010B150001)
文摘A new complex, [Ni（acac）2（NITQ）2]-2CH2C12 1 （acac = acetylacetone, NITQ = 2-（2＂-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide）, was synthesized and charac- terized by elemental analysis, IR spectroscopy, UV-Vis absorption spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 9.6970（19）, b = 20.410（4）, c = 12.166（2） A, β = 93.89（3）°, Mr = 997.43, V= 2402.3（8） A3, Z = 2, Dc = 1.379 g/cm3, F（000） = 1040,μ = 0.684 mm-1, the final R = 0.0423 and wR = 0.1197 for 2884 observed reflections （1 〉 2σ（I））. Compound 1 is found to assume a mononuclear structure, which is further linked into a three-dimensional （3D） supramolecular network by hydrogen-bonding, C1...O weak contact and π...π stacking interactions. Moreover, the luminescent properties of the ligand and compound 1 were further investigated in detail.
基金This work was supported by the National Natural Science Foundation of China (No. 20271029)
文摘A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal structure was determined by X-ray diffraction method. The complex crystallizes in monoclinic, space group P21/n with a = 9.913(4), b = 19.057(8), c = 10.169(4) ? b = 114.292(7), V = 1751(1) 3, C26H38Cu2N8O14, Mr = 813.72, Dc = 1.543 g/cm3, m(MoKa) = 1.290 mm-1, F(000) = 840, Z = 2, the final R = 0.0398 and wR = 0.0986 for 1878 observed reflections (I>2s(I)). The imino nitroxide 2-(2-pyridyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl (im2-py) is reduced in the reaction to yield Him2-py which consists of oxalato-bridged centrosymmetric [Cu2(m-C2O4)(Him2-py)2(H2O)2]2+ ions and noncoordinated NO3- anions. Each copper(II) ion is in a distorted tetragonal pyramid environment: two nitrogen atoms from Him2-py and two oxygen atoms from the oxalate group are in the basal plane, and one water molecule at the axial position.
基金the National Natural Science Foundation of China (No. 20271029)
文摘A new complex of formula [Co(nitmpy)2(tp)(H2O)2]n (nitmpy = 2-(3-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and tp = terephthalato dianion) has been synthesized and structurally characterized. The complex crystallizes in monoclinic, space group P21/n with a = 10.647(3), b = 11.093(3), c = 16.647(5) ? b = 106.185(6), V = 1888.2(10) 3, C32H40CoN6O10, Mr = 727.63, Dc = 1.280 g/cm3, m(MoKa) = 0.513 mm-1, F(000) = 762, Z = 2, the final R = 0.0549 and wR = 0.1265 for 1753 observed reflections (I > 2s(I)). The crystal structure consists of neutral infinite chains where the Co(nitmpy)2(H2O)2 units are linked by terephthalate ligands, and the 1-D chains develop into two-dimensional network via the hydrogen bond interactions.
基金supported by the National Natural Science Foundation of China (Nos. 20471026 and 20771054)the Henan Tackle Key Problem of Science and Technology (No. 0524220001)
文摘A new complex [Zn（NIT-1′-MeBzlm）Cl2（H2O）] （NIT-1′-MeBzlm = 2-{2′-[（1′- methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been prepared and structurally characterized by X-ray diffraction method. Crystal data： monoclinic, space group P21/n, Z = 4, C15H21Cl2N4O3Zn, Mr = 441.63, a = 7.2225（10）, b = 30.849（4）, c = 8.8758（13）A, β = 103.904（2）°, V = 1919.6（5）A^3, Dc = 1.528 g/cm^3, μ（MoKα） = 1.579 mm^-1, F（000） = 908, R = 0.0436 and wR = 0.1029 for 2456 observed reflections with I〉 2σ（I）. X-ray analysis reveals that the Zn（Ⅱ） ion is four-coordinated with a distorted tetrahedron. There also exist H-bonds, π-π piling interactions and weak intermolecular contacts between the NO groups which form a mutual stagger 3-D network configuration. Magnetic investigation reveals that there exists intermolecular antiferro- and ferromagnetic interactions in the title complex.
基金Supported by the National Natural Science Foundation of China (Nos. 20471026 and 20771054)the Henan Tackle Key Problem of Science and Technology (No. 0524220001)
文摘A new one-dimensional dicyanamide bridged zinc（Ⅱ） complex containing nitronyl nitroxide radicals [Zn（NO3）（NIT-1′-MeBzIm）（dca）]n·（H2O）n （NIT-1′-MeBzIm = 2-{2′-[（1′-methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, dca = dicyanamide anion） has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P^-1, with a = 7.428（3）, b = 9.839（3）, c = 16.708（6） A^°, α = 93.270（4）, β = 101.642（4）,γ= 100.632（4）°, C17.5H21N8O5.5Zn, Mr = 496.79, V = 1169.7（7） A^°^3, Dc = 1.411 g/cm^3, μ（MoKα） - 1.096 mm^-1, Z = 2, F（000） = 512, R = 0.0583 and wR = 0.1663 for 4295 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that the zinc（Ⅱ） ion is six-coordinated with a distorted octahedral geometry. These units develop as 1D species where dicyanamide ligands bridge zine（ID ions. In addition, molecules are linked by π-π piling interactions to form 1-D double-chains. Magnetic investigation indicates that the weak intramolecular interactions are antiferromagnetic with J = -0.27 cm^-1, where the spin Hamitonian is defined as H = -2∑ijJijSiS within the complex.
基金supported by the National Natural Science Foundations of China (Nos. 20771054 and 21071074)
文摘A novel azide-bridged copper（Ⅱ） coordination polymer, [Cu3（NITpPy）4（N3）6]n （NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazline-3-oxide-1-oxyl）, was structurally and magnetically characterized. It crystallizes in the triclinic space group P with a = 7.6932（10）, b = 14.5556（19）, c = 16.122（2） , α = 108.443（2）, β = 95.251（2）, γ = 104.236（2）°, V = 1631.7（4） 3, C48H64Cu3N30O8, Mr = 1379.87, Z = 1, Dc = 1.404 g/cm3, μ（MoKα） = 1.041 mm-1, F（000） = 713, the R = 0.0510 and wR = 0.1185 for 4285 observed reflections with I 2σ（I）. X-ray analysis reveals that the Cu（Ⅱ） ions are linked by nitrogen atom of μ1,1 azido ligands to form a Cu-Cu-Cu unit. The units are linked by μ1,3 azido ligands through a bridging style to form a one-dimensional coordination polymer. The variable-temperature magnetic susceptibility data of the complex show ferromagnetic interactions in the complex.
基金supported by the National Natural Science Foundation of China (Nos 20471026 and 20771054)the Natural Science Foundation of Henan Province (No 0311021200)
文摘A new oxalato-bridged dinickel（Ⅱ） complex [Ni2（NIT-MeImz）4（C2O4）]（Ac）2·8H2O has been synthesized and characterized structurally as well as magnetically.It crystallizes in monoclinic,space group C2/c with a=24.608（4）,b=21.399（3）,c=17.992（3）,β=131.680（2）°,V=7076（2）3,C50H86N16Ni2O24,Mr=1412.77,Z=4,Dc=1.326 g/cm3,μ（MoKα）=0.614 mm-1,F（000）=2984,R=0.0751 and wR=0.1791 for 2956 observed reflections with Ⅰ＆gt;2σ（Ⅰ）.X-ray analysis reveals that the crystal structure consists of [Ni2（NIT-MeImz）4（C2O4）]2＋ moiety and two Ac^- anions. Each nickel（H） ion is six-coordinated with a distorted octahedral geometry： two nitrogen atoms and two oxygen atoms from NIT-Melmz together with two other oxygen atoms from the oxalato ion. The 2-D net structure is formed and arranged through intermolecular H-bonding interactions. Magnetic measurements show antiferromagnetic interactions for this complex.
