A novel technique for the determination of the hydroxyl radical is described in this paper. The method employed the reaction of hydroxyl radical with dimethyl sulfoxide to generate a methyl radical quantitatively, whi...A novel technique for the determination of the hydroxyl radical is described in this paper. The method employed the reaction of hydroxyl radical with dimethyl sulfoxide to generate a methyl radical quantitatively, which then coupled with the nitroxide linked naphthalene and led to a large increase in fluorescence intensity. The proposed method was demonstrated to be capable of detecting hydroxyl radicals generated in the Fenton systems. It proved to be a simple and sensitive technique for the determination of hydroxyl radicals.展开更多
The electrochemistry of pyridoxine (vitamin B6, VB6) was studied by cyclic voltammetry at a glassy carbon electrode. The electrochemical response of VB6 could be significantly enhanced by using 4-hydroxy-2,2,6,6-tetra...The electrochemistry of pyridoxine (vitamin B6, VB6) was studied by cyclic voltammetry at a glassy carbon electrode. The electrochemical response of VB6 could be significantly enhanced by using 4-hydroxy-2,2,6,6-tetra- methylpiperidine-N-oxyl (HO-TEMPO) as a mediator via an electrocatalytic EC' mechanism with the oxoammo-nium ion of HO-TEMPO as the active oxidant. The catalytic rate constant was determined to be 5.4×103 (mol L-1)-1s-1 by using chronoamperometry.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 novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3)·EtOH]n was synthesized and characterized structurally and magnetically. It crystallizes i...A novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3)·EtOH]n was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group p21/n. Each Mn(II) ion is six-coordinated in a distorted octahedral environment. The two N atoms of the nitronyl nitroxide radical and the two O atoms of acetate ligands are in the equatorial plane, whereas the two different azido bridging ligands are in trans axial position. Mn(II) ions are linked by nitrogen atom of μ1,1-azido and oxygen atoms of two carboxy groups to form a Mn-Mn unit. Mn-Mn units are linked by azido ligands through μ1,3 bridging style to form a one-dimensional chain. The compound is connected by the coordination bonds, π-π interactions and hydrogen bonds as a three-dimensional structure. Magnetic susceptibility data support that there are stronger antiferromagnetic interactions between the radical and Mn(II) ion, weak antiferromagnetic interactions between the Mn-R units, and very weak antiferromagnetic interactions between the R-Mn-Mn-R units.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
A novel heterospin one-dimensional (1-D) chain complex containing both Cu(Ⅱ) and nitroxide radical ligands, {[Cu(tcph)(H2O)4][Cu(tcph)(NIT3Py)2]·2H2O}n (1) (H2tcph = tetrachloro-phthalic acid, NIT3Py = 2-(3′-py...A novel heterospin one-dimensional (1-D) chain complex containing both Cu(Ⅱ) and nitroxide radical ligands, {[Cu(tcph)(H2O)4][Cu(tcph)(NIT3Py)2]·2H2O}n (1) (H2tcph = tetrachloro-phthalic acid, NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), has been synthesized and structurally characterized. The structure consists of neutral chains of copper(Ⅱ) ions bridged by tcph and coordinated alternatively by nitroxide radicals as spin branches and solvated water as co-ligand. The magnetic data were fitted using an approximate theoretical model based on population analysis to obtain the coupling parameter values of JCu2-Rad = 22.4 cm-1 and J′Cu1-Cu2 = -2.4 cm-1, indicating the intramolecular ferromagnetic interaction between Cu(Ⅱ) and NIT3Py and weak antiferromagnetic interaction between Cu1 and Cu2 linked by tcph.展开更多
A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structura...A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604（7）, b = 10.3012（7）, c = 16.6684（12）A, β = 105.0290（10）^o, V = 1552.25（19）A3, C24H34CUN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm^3,μ（MoKα） = 0.876 mm^-1, F（000） = 650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper（Ⅱ） ion as an unusual didentate chelate with a k-2 N（MeImz）,O（IM） mode in the complex. The square-planar coordination sites at Cu（Ⅱ） are occupied by two 0 and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu（Ⅱ） ion and radicals.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
To allow anisotropies of optical properties in a magnetic field, nitroxide radical is introduced into the ortho-position of the phenylene ring in the side chain. A new azobenzene side-chain polymer (TEMPO-PAZ) contain...To allow anisotropies of optical properties in a magnetic field, nitroxide radical is introduced into the ortho-position of the phenylene ring in the side chain. A new azobenzene side-chain polymer (TEMPO-PAZ) containing TEMPO radical was synthesized. The polymer has a good solubility in organic solvents. The ESR spectrum of the polymer indicated three absorption lines characteristic of TEMPO radical. The optical phase conjugated responses (I-4) of the polymer films were investigated by degenerate four-wave mixing (DFWM). The experimental results showed that optical phase conjugated response of the TEMPO-PAZ could be easily controlled by choosing the appropriate direction of magnetic field presumably due to the nitroxide radical in the TEMPO-PAZ molecular structure. For the polymer investigated here, the nitroxide radical was introduced to increase optical phase conjugated response intensity in a magnetic field, aiming originally at searching for a new photo-active organic magnetic multifunctional materials.展开更多
A new one-dimensional （1-D） Zn（Ⅱ） nitronyl nitroxide complex bridged by pyridine-2,4-dicarboxylate anion, [Zn（NIT4Py）（2,4-PDA）（H2O）2], （NIT4Py = 2-（4′-pyridyl）-4,4,5,5- tetramethylimidazoline-1-oxyl-3-o...A new one-dimensional （1-D） Zn（Ⅱ） nitronyl nitroxide complex bridged by pyridine-2,4-dicarboxylate anion, [Zn（NIT4Py）（2,4-PDA）（H2O）2], （NIT4Py = 2-（4′-pyridyl）-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide and 2,4-PDA = pyridine-2,4-dicarboxylate anion）, has been synthesized and structurally characterized by X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 16.834（2）, b = 7.4376（10）, c = 18.295（3） A, β = 102.848（2）°, V = 2233.2（5） A^3, C19H23N4O3Zn, Mr = 500.78, Dc = 1.489 g/cm^3,μ（MoKa） = 1.152 mm^-1, F（000） = 1036, Z = 4, the final R = 0.0390 and wR = 0.0915 for 3234 observed reflections. In the complex, each zinc（Ⅱ） ion is six-coordinated by one nitrogen atom of the radical ligand （NIT4Py）, one nitrogen atom and two oxygen atoms of two 2,4-PDA anions and two oxygen atoms of two water molecules. Each 2,4-PDA anion bridges two Zn（Ⅱ） ions via a tridentate mode into a 1-D chain, and these 1-D chains are further linked into a 2-D network via hydrogen-bonding interactions.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
Using two new flexible and functional nitronyl nitroxide radicals as ligands, two copper (II) complexes {[Cu(hfac)<sub>2</sub>]<sub>3</sub>(NITmPhO3Py)<sub>2</sub>}<sub>n...Using two new flexible and functional nitronyl nitroxide radicals as ligands, two copper (II) complexes {[Cu(hfac)<sub>2</sub>]<sub>3</sub>(NITmPhO3Py)<sub>2</sub>}<sub>n</sub> (1) and [Cu(hfac)<sub>2</sub><sub> </sub>(NIToPhO3Py)]<sub>2</sub> (2) (NITmPhO3Py = 2-[(3-methoxy-pyridinyl)phen-3-yl]- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NIToPhO3Py = 2-[(3-methoxy-pyridinyl)phen-2-ly]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetone), have been characterized structurally and magnetically. The X-ray crystal analyses showed that complex 1 displayed a chain polymer structure which formed with {[Cu(hfac)<sub>2</sub>]<sub>3</sub>(NITmPhO3Py)<sub>2</sub>}<sub>n</sub> due to the cross-linking of two cyclic binuclear fragments {[Cu(hfac)<sub>2</sub>]<sub>2</sub>(NITmPhO3- Py)<sub>2</sub>} via the bridging unit [Cu(hfac)<sub>2</sub>];complex 2 presented a binuclear cyclic structure [Cu(hfac)<sub>2</sub>]<sub>2</sub>(NIToPhO3Py)<sub>2</sub>. The magnetic behaviors of the two complexes 1 and 2 have been investigated. Magnetic studies showed that antiferromagnetic interactions dominated in complex 1, while there existed ferromagnetic interactions between Cu(II) and coordinated NO group in complex 2.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
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 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
文摘A novel technique for the determination of the hydroxyl radical is described in this paper. The method employed the reaction of hydroxyl radical with dimethyl sulfoxide to generate a methyl radical quantitatively, which then coupled with the nitroxide linked naphthalene and led to a large increase in fluorescence intensity. The proposed method was demonstrated to be capable of detecting hydroxyl radicals generated in the Fenton systems. It proved to be a simple and sensitive technique for the determination of hydroxyl radicals.
基金Project supported by the National Natural Science Foundation of China (Nos. 20172025 and 20332020).
文摘The electrochemistry of pyridoxine (vitamin B6, VB6) was studied by cyclic voltammetry at a glassy carbon electrode. The electrochemical response of VB6 could be significantly enhanced by using 4-hydroxy-2,2,6,6-tetra- methylpiperidine-N-oxyl (HO-TEMPO) as a mediator via an electrocatalytic EC' mechanism with the oxoammo-nium ion of HO-TEMPO as the active oxidant. The catalytic rate constant was determined to be 5.4×103 (mol L-1)-1s-1 by using chronoamperometry.
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This work was supported by the National Natural Science Foundation of China(Grant Nos.20071019 and 90101028).
文摘A novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3)·EtOH]n was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group p21/n. Each Mn(II) ion is six-coordinated in a distorted octahedral environment. The two N atoms of the nitronyl nitroxide radical and the two O atoms of acetate ligands are in the equatorial plane, whereas the two different azido bridging ligands are in trans axial position. Mn(II) ions are linked by nitrogen atom of μ1,1-azido and oxygen atoms of two carboxy groups to form a Mn-Mn unit. Mn-Mn units are linked by azido ligands through μ1,3 bridging style to form a one-dimensional chain. The compound is connected by the coordination bonds, π-π interactions and hydrogen bonds as a three-dimensional structure. Magnetic susceptibility data support that there are stronger antiferromagnetic interactions between the radical and Mn(II) ion, weak antiferromagnetic interactions between the Mn-R units, and very weak antiferromagnetic interactions between the R-Mn-Mn-R units.
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.
基金Supported by the National Natural Science Foundation of China (Grant No. 20631030)973 Project (Grant No. 2007CB815305)+1 种基金Natural Science Foundation of Tianjin (Grant No. 09JCYBJC05500)100 Projects of Creative Research for the Undergraduates of Nankai University in China (Grant No. BX7-207).
文摘A novel heterospin one-dimensional (1-D) chain complex containing both Cu(Ⅱ) and nitroxide radical ligands, {[Cu(tcph)(H2O)4][Cu(tcph)(NIT3Py)2]·2H2O}n (1) (H2tcph = tetrachloro-phthalic acid, NIT3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), has been synthesized and structurally characterized. The structure consists of neutral chains of copper(Ⅱ) ions bridged by tcph and coordinated alternatively by nitroxide radicals as spin branches and solvated water as co-ligand. The magnetic data were fitted using an approximate theoretical model based on population analysis to obtain the coupling parameter values of JCu2-Rad = 22.4 cm-1 and J′Cu1-Cu2 = -2.4 cm-1, indicating the intramolecular ferromagnetic interaction between Cu(Ⅱ) and NIT3Py and weak antiferromagnetic interaction between Cu1 and Cu2 linked by tcph.
基金This work was supported by the N N S F of China (No. 20471026)the Natural Science Foundation of Henan Province (No. 0311021200)
文摘A new copper（Ⅱ） compound with imino nitroxide radicals [Cu（IM-MeImz）2].（SCN）2 （IM-meImz =2-（5-methylimidazol-4-yl）-4,4,5,5-tetramethyl-2-imidazoline- 1-oxyl） has been synthesized and characterized structurally and magnetically. It crystallizes in monoclinic, space group P21/c with a = 9.3604（7）, b = 10.3012（7）, c = 16.6684（12）A, β = 105.0290（10）^o, V = 1552.25（19）A3, C24H34CUN10O2S2, Mr = 622.27, Z = 2, Dc = 1.331 g/cm^3,μ（MoKα） = 0.876 mm^-1, F（000） = 650, the final R = 0.0374 and wR = 0.1079. X-ray analysis demonstrates that the IM-MeImz ligand is coordinated to the copper（Ⅱ） ion as an unusual didentate chelate with a k-2 N（MeImz）,O（IM） mode in the complex. The square-planar coordination sites at Cu（Ⅱ） are occupied by two 0 and two N atoms from the imino nitroxide radicals. The complex molecules are connected as a onedimensional polymer structure by intermolecular interactions. Magnetic measurements show that there are intramolecular antiferromagnetic interactions between the Cu（Ⅱ） ion and radicals.
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This work was supported by National Natural Science Foundation of China (No. 20134010) and Scientific Foundation for Returned Overseas Chinese Scholars. Ministry of Education.
文摘To allow anisotropies of optical properties in a magnetic field, nitroxide radical is introduced into the ortho-position of the phenylene ring in the side chain. A new azobenzene side-chain polymer (TEMPO-PAZ) containing TEMPO radical was synthesized. The polymer has a good solubility in organic solvents. The ESR spectrum of the polymer indicated three absorption lines characteristic of TEMPO radical. The optical phase conjugated responses (I-4) of the polymer films were investigated by degenerate four-wave mixing (DFWM). The experimental results showed that optical phase conjugated response of the TEMPO-PAZ could be easily controlled by choosing the appropriate direction of magnetic field presumably due to the nitroxide radical in the TEMPO-PAZ molecular structure. For the polymer investigated here, the nitroxide radical was introduced to increase optical phase conjugated response intensity in a magnetic field, aiming originally at searching for a new photo-active organic magnetic multifunctional materials.
基金This work was supported by the National Natural Science Foundation of China (No. 20331010 and 20571045)
文摘A new one-dimensional （1-D） Zn（Ⅱ） nitronyl nitroxide complex bridged by pyridine-2,4-dicarboxylate anion, [Zn（NIT4Py）（2,4-PDA）（H2O）2], （NIT4Py = 2-（4′-pyridyl）-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide and 2,4-PDA = pyridine-2,4-dicarboxylate anion）, has been synthesized and structurally characterized by X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 16.834（2）, b = 7.4376（10）, c = 18.295（3） A, β = 102.848（2）°, V = 2233.2（5） A^3, C19H23N4O3Zn, Mr = 500.78, Dc = 1.489 g/cm^3,μ（MoKa） = 1.152 mm^-1, F（000） = 1036, Z = 4, the final R = 0.0390 and wR = 0.0915 for 3234 observed reflections. In the complex, each zinc（Ⅱ） ion is six-coordinated by one nitrogen atom of the radical ligand （NIT4Py）, one nitrogen atom and two oxygen atoms of two 2,4-PDA anions and two oxygen atoms of two water molecules. Each 2,4-PDA anion bridges two Zn（Ⅱ） ions via a tridentate mode into a 1-D chain, and these 1-D chains are further linked into a 2-D network via hydrogen-bonding 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 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.
文摘Using two new flexible and functional nitronyl nitroxide radicals as ligands, two copper (II) complexes {[Cu(hfac)<sub>2</sub>]<sub>3</sub>(NITmPhO3Py)<sub>2</sub>}<sub>n</sub> (1) and [Cu(hfac)<sub>2</sub><sub> </sub>(NIToPhO3Py)]<sub>2</sub> (2) (NITmPhO3Py = 2-[(3-methoxy-pyridinyl)phen-3-yl]- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NIToPhO3Py = 2-[(3-methoxy-pyridinyl)phen-2-ly]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetone), have been characterized structurally and magnetically. The X-ray crystal analyses showed that complex 1 displayed a chain polymer structure which formed with {[Cu(hfac)<sub>2</sub>]<sub>3</sub>(NITmPhO3Py)<sub>2</sub>}<sub>n</sub> due to the cross-linking of two cyclic binuclear fragments {[Cu(hfac)<sub>2</sub>]<sub>2</sub>(NITmPhO3- Py)<sub>2</sub>} via the bridging unit [Cu(hfac)<sub>2</sub>];complex 2 presented a binuclear cyclic structure [Cu(hfac)<sub>2</sub>]<sub>2</sub>(NIToPhO3Py)<sub>2</sub>. The magnetic behaviors of the two complexes 1 and 2 have been investigated. Magnetic studies showed that antiferromagnetic interactions dominated in complex 1, while there existed ferromagnetic interactions between Cu(II) and coordinated NO group in complex 2.
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.
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.
