2,6-二(苯并咪唑-2′)吡啶与钴(Ⅱ)的显色反应

在 (CTMAB)存在下 ,在 p H =3.5— 4 .5的 HAc- Na Ac缓冲溶液中 ,2 ,6 -二 (苯并咪唑 - 2′)吡啶(H2 Bzimpy)与钴 ( )形成稳定的 3∶ 1配合物 ,其最大吸收波长为 36 0 .6 nm,表观摩尔吸光系数为 4 .4 6 7× 1 0 4L· mol-1 · cm-1 ,钴 ( )的质量浓度在 0— 2 0μg/ 2 5 m L范围内服从比耳定律。该法用于维生素 B1 2 和含钴分子筛中微量钴的测定 ,结果令人满意     

离子缔合物光度法测定微量BrO3-

在 0 .1 6 mol/ L H2 SO4介质中 ,2 - (5 -氯 - 2 -吡啶偶氮 ) - 5 -二乙氨基苯酚 (5 - Cl- PADAP)与 Br O-3 和 SCN-形成紫红色三元离子缔合物 ,最大吸收波长为 5 6 0 nm,表观摩尔吸光系数为 1 .9× 1 0 4L· mol-1 · cm-1 ,Br O-3 含量在 0— 2× 1 0 -5mol/ L范围内符合比耳定律。方法可用于化学试剂中微量 Br O-3 的测定。     

分光光度法测定烟草样品中的钙

在 p H为 8.0的柠檬酸钠 -氢氧化钠缓冲介质中 ,Triton X- 10 0存在下 ,2 - [2 - (4 -甲基喹啉 ) -偶氮 ]- 5 -二乙氨基苯酚 (QADP)与钙显色反应 ,生成 1∶ 1稳定络合物 ,λmax=5 70 nm,ε=5 .12× 10 4L· mol-1·cm-1。钙含量在 0— 2 0 μg/2 5 m L范围内符合比耳定律 ,方法用于烟草中钙含量的测定 ,结果令人满意。     

钒(Ⅴ)-5-Br-PADAP-H2O2-吐温-80显色体系的研究与应用

研究了在非离子表面活性剂吐温 - 80存在下 ,钒 ( )与 2 - [(5 -溴 - 2 -吡啶 ) -偶氮 ]- 5 -二乙氨基苯酚 (5 -Br- PADAP)及 H2 O2 的显色反应。实验表明 :在 p H1.5— 4 .0范围内 ,钒 ( )与 5 - Br- PADAP、H2 O2 形成稳定的配合物 ,最大吸收峰位于 5 95 nm处 ,表观摩尔吸光系数为 6 .2× 10 4L· mol-1· cm-1,配合物组成比为钒 ( )∶ 5 - Br- PADAP∶ H2 O2 =1∶ 1∶ 1。钒含量在 0— 15μg/ 2 5 m L范围内服从比耳定律。该方法灵敏度较高 ,用于合成水样中钒的测定 ,结果令人满意。     

2-(2-喹啉偶氮)-间苯二酚固相萃取光度法测定镉

在 p H=8.0的硼酸 -氢氧化钠缓冲介质中 ,Triton X- 10 0存在下 ,2 - (2 -喹啉偶氮 ) -间苯二酚 (QAR)与镉反应生成 2∶ 1稳定络合物 ,最大吸收波长为 5 45 nm,摩尔吸光系数ε=6 .88× 10 4L· mol-1· cm-1。样品中的镉用强阴离子交换固相萃取柱固相萃取预分离和富集后 ,光度法测定 ,结果令人满意     

4-(2-羟基-4-硝基苯偶氮)-1-苯基-3-甲基吡唑啉酮光度法测定烟草中镁

研究了 4 - (2 -羟基 - 4-硝基苯偶氮 ) - 1-苯基 - 3-甲基吡唑啉酮 (HNAPMP)与镁的显色反应 ,在 p H=10的硼砂 -氢氧化钠缓冲介质中 ,HNAPMP与镁反应生成 2∶ 1稳定络合物 ,λmax=5 2 2 nm,ε=3.5 8× 10 4L·mol-1· cm-1。镁含量在 0— 2 0 μg/2 5 m L范围内符合比耳定律 ,方法用于烟草样品中镁含量的测定 ,结果令人满意     

2-羟基-4-磺酰氨基苯重氮氨基偶氮苯的合成及与锌的显色反应

在 Triton X- 10 0表面活性剂存在下 ,p H=9.5— 11.5的 Na2 B4O7- Na OH缓冲溶液中 ,2 -羟基 - 4-磺酰氨基苯重氮氨基偶氮苯 (HSDAA)与锌 ( )生成 2∶ 1型深红色配合物。最大吸收峰为 λ=5 30 nm处 ,表观摩尔吸光系数为 1.2 4× 10 5L· mol-1· cm-1。 Zn2 的浓度在 0— 4 80μg/L范围内符合比耳定律。用于测定样品中的微量锌 ,结果满意。     

2-(2-喹啉偶氮)-1,5-苯二酚固相萃取光度法测定银的研究

研究了新试剂 2 (2 喹啉偶氮 ) 1,5 苯二酚 (QADHB)与银的显色反应 ,在 pH =5 0柠檬酸 氢氧化钠 (内含 0 0 1mol·L- 1 Na2 EDTA)缓冲介质中 ,十二烷基磺酸钠 (SDS)存在下 ,QADHB与银反应生成摩尔比为 2∶1的稳定络合物 ,该络合物可被WatersSep ParkC1 8固相萃取小柱萃取富集。富集在小柱上的络合物用乙醇 (含 1%乙酸 )洗脱后 ,在乙醇介质中 ,其吸收光谱的λmax=5 5 0nm ,ε=6 99× 10 4 L·mol- 1 ·cm- 1 。银含量在 0～ 1 2 μg·mL- 1 范围内符合比尔定律。方法用于环境水样中痕量银的测定 ,结果令人满意     

1-偶氮苯-3-(5-氯-2-吡啶)-三氮烯的合成及与锌的显色反应

合成了新显色剂1-偶氮苯-3-(5-氯-2-吡啶)-三氮烯.在表面活性剂OP存在下,pH为10.5-11.5的Na2B4O7-NaOH缓冲溶液中,新显色剂1-偶氮苯-3-(5-氯-2-吡啶)-三氮烯与锌发生显色反应,生成4∶1的红色配合物.配合物的最大吸收峰位于530nm,表观摩尔吸光系数为1.25×105L·mol-1·cm-1,Zn2 浓度在0-480μg/L范围内遵守比耳定律.测定废水中微量锌,结果令人满意.     

2-(2-喹啉偶氮)-1,5-苯二酚分光光度法测定烟草样品中的钙

在 p H为 8.0的柠檬酸钠 -氢氧化钠缓冲介质中 ,Triton X- 10 0存在下 ,2 - (2喹啉偶氮 ) - 1,5苯二酚(QADHB)与钙反应生成 1∶ 1稳定配合物 ,λmax=5 5 5 nm,ε=4 .18× 10 4L· mol-1· cm-1。钙含量在 0 .1—2 5μg/ 2 5 m L的范围内符合比耳定律 ,方法用于烟草中钙含量的测定 ,结果令人满意。     

The magnetic phase in 2-2-1-2 superconducting materials

Three related aspects of the magnetic phase diagram are presented here: the first deals with the disruption of the antiferromagnetic order in the electron rich phase obtained by Ce doping, the second concern the role of Bi planes as a sink-buffer of carriers, the third focuses the magnetization vs. temperature curves in a variety of different bilayer materials as seen by the muons and discusses the “anomalous” behaviour in relation to theoretical predictions and neutron scattering data.     

A Quantum Monte Carlo Study on Mixed-Spin Chains of 1／2-1／2-1-1 and 3／2-3／2-1-1

The ground-state and thermodynamic properties of quantum mixed-spin chains of 1/2-1/2-1-1 and 3/2-3/2-1-1 are investigated by a quantum Monte Carlo simulation with the loop-cluster algorithm. For 1/2-1/2-1-1 chain, we find it hastwo phases separated by an energy-gap vanishing point in the ground-state. For 3/2-3/2-1-1 chain,the numerical results show two energy-gap vanishing points isolated by different phases in its ground-state. Our calculations indicate that all these ground state phases can be understood by means of valence-bond-solid picture, and the thermodynamic behavior at finite temperatures is continuous as a function of parameter α=J2/J1.     

A Quantum Monte Carlo Study on Mixed-Spin Chains of 1/2-1/2-1-1 and 3/2-3/2 -1-1

The ground-state and thermodynamic properties of quantum mixed-spin chains of1/2-1/2-1-1and 3/2-3/2-1-1are investigated by a quantum Monte Carlo simulation with the loop-cluster algorithm. For 1/2-1/2-1-1 chain, we find it has two phases separated by an energy-gap vanishing point in the ground-state. For 3/2-3/2-1-1 chain, the numerical results show two energy-gap vanishing points isolated by different phases in its ground-state. Our calculations indicate that all these ground state phases can be understood by means of valence-bond-solid picture, and the thermodynamic behavior at finite temperatures is continuous as a function of parameterα=J2/J1.     

2-甲基-6-(2-甲苯基)-2-庚烯的波谱学研究

采用色谱法从蒲儿根花部位中分离得到2-甲基-6-(2-甲苯基)-2-庚烯,该化合物第一次以单体的形式得到,通过测定氢-氢相关谱(1H-1H COSY)、DEPT谱、异核单量子相关谱(HSQC)及异核多键相关谱(HMBC)等二维谱确定了该化合物的结构,并对该化合物的1H NMR和13C NMR谱进行了归属.     

An unusual synthesis of 3-(2-(arylamino)thiazol-4-yl)-2H-chromen-2-ones from ethyl 2-(chloromethyl)-2-hydroxy-2H-chromene-3-carboxylate via benzopyran ring opening

An unusual and unexpected synthesis of 3-(2-(arylamino)thiazol-4-yl)-2H-chromen-2-ones has been observed by the reaction of ethyl 2-(chloromethyl)-2-hydroxy-2H-chromene-3-carboxylate with various arylthioureas in ethanol under mild reaction conditions with excellent yields. The ambiguity in the structure of the obtained products has been solved by recording its single-crystal X-ray analysis. This protocol has been found to be a novel approach for the preparation of title compounds via benzopyran ring opening. A systematic plausible mechanism has been proposed for the formation of the product. Also, an efficient one-pot three-component method has been demonstrated for the formation of title compounds starting from salicylaldehyde.

     

Novel and convenient synthesis of 1-(pyridinylmethyl)-2-naphthols and 1-(pyridinylmethylene)-2-tetralones from 2-tetralones

The reaction of 2/4-pyridine carboxaldehyes with 2-tetralone analogs in the presence of catalytic amounts of Pd/C and trimethylsilyl chloride in DMF resulted in the formation of 1-(pyridin-2/4-ylmethyl)-2-naphthols in moderate to good yields as opposed to the expected 1-(pyridin-2/4-ylmethylene)-2-tetralones. 3-Pyridine carboxaldehyde, however, formed 1-(pyridin-3-ylmethylene)-2-tetralones with 2-tetralone analogs under similar conditions. When representative reactions were repeated in the presence of anhydrous HCl gas in acetic acid, including one with 3-pyridine carboxaldehyde, 1-(pyridinylmethyl)-2-naphthols were the only products obtained with significantly improved yields. A possible mechanism explaining these results is discussed.     

Identification ofμ +-sites in the 1-2-3 compoundin the 1-2-3 compound

Possibleμ ⁺ sites have been identified by a comparison of measured spontaneous internal fields in YBa₂Cu₃O_6+δ and REBa₂Cu₃O_7−δ and of measured second moments and width of transverse field powder spectra with the corresponding calculated quantities. In the YBa₂Cu₃O₇ system only one possibleμ ⁺ site emerges at a distance of ∼1.05 A from a chain oxygen O(4) at the position (0.15(1), 0.44(1), 0.071(1)). In the system YBa₂Cu₃O₆ the only possibleμ ⁺ sites are near to an oxygen O(1) with z/c=0.133 and the same distance as above. The analysis leads also to improved valuesμ _Ho = 2.2(1)μ _B andμ _Cu = 0.67(4)μ _B and to a determination of the latters direction:μ _Cu ‖〈110〉.     

Mössbauer study of tin-doped 1-2-3 and 2-1-4 highT c superconductors

Samples of YBa₂(Cu_0.85Sn_0.15)₃O_7–y (1-2-3), La₂(Cu_0.95Sn_0.05)O4_4–x, and La_1.85Ba_0.15(Cu_0.95Sn_0.05)O_4–x (2-1-4), with different oxygen stoichiometry, have been studied by Mössbauer spectroscopy. These measurements reveal the existence of two inequivalent sites for Sn in the (1-2-3) compounds. The (1-2-3) spectra display two quadrupole doublets which we associate with Sn in Cu(1) and Cu(2) sites, respectively. La compounds show a single quadrupole doublet.