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1.
化学体系中随机共振现象的特性、机理、本质和应用的研究是非常重要的前沿课题。综述中国科学技术大学非线性化学实验室,在化学体系随机共振现象的理论研究中,所取得的主要成果,并阐述化学体系随机共振现象研究中所提出来的若干重要问题:非均相化学体系中随机共振;化学体系中内信号随机共振;化学体系中多重随机共振;化学体系中随机共振的调制;化学体系中色噪声作用下的随机共振;化学体系中时空随机共振;耦合化学体系中随机共振;化学体系中双参量随机共振。  相似文献   

2.
混杂光固化或双重固化是指在同一体系中采用两种或两种以上不同类型的聚合反应来使体系固化的方法 ,它是原位改性高分子的一种新方法 .混杂光固化体系包括自由基 阳离子混杂光固化体系、自由基 缩聚混杂体系和自由基 自由基混杂体系等 .本文综述了混杂光固化体系的原理及其应用  相似文献   

3.
多组分高分子体系动态流变学研究   总被引:16,自引:0,他引:16  
根据动态流变学基本理论介绍了多组分高分子体系动态流变学行为,评述了动态流变学方法在研究高分子共混体系、嵌段共聚物体系、填充高分子体系及溶胶-凝胶体系的形态、结构方面的最新进展,认为动态流变学方法是研究多组分高分子体系形态与结构的一种有效方法。  相似文献   

4.
刘艳  刘璐  付玲  江虹 《分析试验室》2022,41(1):90-95
采用定性与定量相结合,建立了测定饮料及糖果中共存色素亮蓝(BRIB)、苋菜红(AMA)及柠檬黄(TAR)的简便吸收光谱法。BRIB,AMA及TAR在pH 3.50 Tris-HCl条件下,分别与乙基绿反应生成离子缔合物,产生新的特征吸收光谱。定量测定波长分别为588 nm(BRIB体系)、532 nm(AMA体系)和426 nm(TAR体系),表观摩尔吸光系数(κ)分别为4.24×10^(4)L/(mol·cm)(BRIB体系)、3.35×10^(4)L/(mol·cm)(AMA体系)和2.64×10^(4)L/(mol·cm)(TAR体系),线性范围分别为0.05~18.8 mg/L(BRIB体系)、0.05~13.3 mg/L(AMA体系)和0.05~11.7 mg/L(TAR体系),检出限分别为35μg/L(BRIB体系)、27μg/L(AMA体系)和30μg/L(TAR体系),定量限分别为0.61 mg/kg(BRIB体系)、0.47 mg/kg(AMA体系)和0.52 mg/kg(TAR体系)。该方法用于市售饮料及糖果中共存BRIB,AMA及TAR的测定,加标回收率为97.8%~103%(BRIB体系)、97.9%~102%(AMA体系)和98.1%~103%(TAR体系),相对标准偏差分别为2.0%~2.8%(BRIB体系),1.2%~2.6%(AMA体系)和1.6%~2.6%(TAR体系)。  相似文献   

5.
丙烯酰胺双水相聚合体系稳定性研究   总被引:11,自引:0,他引:11  
通过浊点滴定法测定了不同温度下PAAmPEGH2O双水相体系相图,发现分相浓度随着温度的升高先增后降,55℃时分相浓度最低.双水相聚合体系微观结构显示,分散相以砾状液滴形式均匀分散在连续相中.研究了聚合过程中聚合体系粘度的变化,以及聚合温度、分散介质、单体、引发剂及乳化剂等对聚合体系最终粘度的影响,聚合体系最终粘度在一定范围内随分散介质和单体浓度增加变化不大,但是超过某一浓度后聚合体系粘度急剧增加;聚合体系中加入少量乳化剂对体系粘度影响不大,但加入大量乳化剂后体系稳定性变差,聚合体系粘度急剧增加;聚合体系最终粘度随着聚合温度升高先降后增,与相图的预测结果一致.  相似文献   

6.
通过光学显微镜观测和流变实验研究了应力弛豫过程中高浓度不相容聚合物共混体系相形态演变与流变性能的关系,发现随体系浓度增大,共混体系内液滴弛豫变慢,同时体系应力弛豫过程变慢,这与高浓度体系中液滴之间相互作用有关.结合有效介质思想提出适用于较高浓度共混体系的形态张量模型,较好地预测了共混体系的相形态与应力弛豫行为.  相似文献   

7.
硫脲氧化反应动力学研究进展   总被引:1,自引:0,他引:1  
本文综述了硫脲氧化反应动力学的研究进展,根据氧化剂和氧化方式不同,将硫脲氧化体系分成含卤氧化体系和非卤氧化体系两大类,其中含卤氧化体系包括亚氯酸、碘酸、溴酸、卤素单质氧化硫脲的反应体系;非卤氧化体系包括双氧水、自由基、电化学和金属酸盐氧化硫脲的反应体系。总结了不同反应体系的动力学现象和反应机理研究状况,文中还介绍了在硫脲氧化反应动力学研究中光电磁及色谱方法的发展状况,提出硫脲氧化反应动力学机理研究突破可能途径。  相似文献   

8.
离子液体在蛋白质萃取分离中的应用   总被引:1,自引:0,他引:1  
离子液体具有独特的物化性质如热稳定性好、不挥发、不易燃和良好的生物兼容性,近年来作为传统有机溶剂的替代物在有机合成、电化学、催化和萃取分离等领域得到了广泛应用。本文简要综述了以离子液体为媒介的萃取体系在蛋白质分离富集和分析中的相关研究和应用进展,包括辅助萃取体系、直接萃取体系、双水相萃取体系、微乳萃取体系、结晶体系和基于离子液体的固相萃取体系等。  相似文献   

9.
采用分子动力学方法建立了二乙基甲苯二胺/双酚A缩水甘油醚环氧树脂体系(DETDA/DGEBA体系)和间苯二胺/双酚A缩水甘油醚环氧树脂体系(mPDA/DGEBA体系)的交联模型,在此基础上,分析了固化剂分子结构的差异对树脂性能的影响,研究发现mPDA/DGEBA体系的玻璃化转变温度、模量以及阻碍水分子的扩散性能均高于DETDA/DGEBA体系。为了进一步揭示交联环氧树脂分子结构与性能之间的关系,研究了上述两体系的自由体积和内聚能密度。结果表明,与DETDA/DGEBA体系相比,mPDA/DGEBA体系具有较小的自由体积和较高的内聚能密度。较小的自由体积和较高的内聚能密度是造成mPDA/DGEBA体系玻璃化转变温度、模量以及阻碍水分子的扩散性能均高于DETDA/DGEBA体系的原因。  相似文献   

10.
本文综述了表面化学反应体系中若干重要非线性问题的研究现状及作者所取得的研究成果, 其中包括表面催化反应体系中的非平衡动力学相变, 分形表面反应体系中的非线性动力学行为, 表面反应体系中噪声诱导的时空有序结构及其转变规律, 表面反应体系中的随机共振等。  相似文献   

11.
Rhodium(III) and iridium(III) complexes containing bis(pyrazolyl)methane ligands (pz = pyrazole, L' in general; specifically, L1 = H2C(pz)2, L2 = H2C(pzMe2)2, L3 = H2C(pz4Me)2, L4 = Me2C(pz)2), have been prepared in a study exploring the reactivity of these ligands toward [Cp*MCl(mu-Cl)]2 dimers (M = Rh, Ir; Cp* = pentamethylcyclopentadienyl). When the reaction was carried out in acetone solution, complexes of the type [Cp*M(L')Cl]Cl were obtained. However, when L1 and L2 ligands have been employed with excess [Cp*MCl(mu-Cl)]2, the formation of [Cp*M(L')Cl][Cp*MCl3] species has been observed. PGSE NMR measurements have been carried out for these complexes, in which the counterion is a cyclopentadienyl metal complex, in CD2Cl2 as a function of the concentration. The hydrodynamic radius (rH) and, consequently, the hydrodynamic volume (VH) of all the species have been determined from the measured translational self-diffusion coefficients (Dt), indicating the predominance of ion pairs in solution. NOE measurements and X-ray single-crystal studies suggest that the [Cp*MCl3]- approaches the cation, orienting the three Cl-legs of the "piano-stool" toward the CH2 moieties of the bis(pyrazolyl)methane ligands. The reaction of 1 equiv of [Cp*M(L')Cl]Cl or [Cp*M(L')Cl][Cp*MCl3] with 1 equiv of AgX (X = ClO4 or CF3SO3) in CH2Cl2 allows the generation of [Cp*M(L')Cl]X, whereas the reaction of 1 equiv of [Cp*M(L')Cl] with 2 equiv of AgX yields the dicationic complexes [Cp*M(L')(H2O)][X]2, where single water molecules are directly bonded to the metal atoms. The solid-state structures of a number of complexes were confirmed by X-ray crystallographic studies. The reaction of [Cp*Ir(L')(H2O)][X]2 with ammonium formate in water or acetone solution allows the generation of the hydride species [Cp*Ir(L')H][X].  相似文献   

12.
The reactions of [Cp*MCl2]2(Cp*=eta5-C5Me5, M = Rh, Ir) with thiacalix[4]arene (TC4A(OH)4) and tetramercaptothiacalix[4]arene (TC4A(SH)4) gave the mononuclear complexes [(Cp*M){eta3-TC4A(OH)2(O)2}] and the dinuclear complexes [(Cp*M)2{eta3eta3-TC4A(S)4}] respectively, while the analogous reactions with dimercaptothiacalix[4]arene (TC4A(OH)2(SH)2) produced the tetranuclear complexes [(Cp*M)2(Cp*MCl2)2-{eta3eta3eta1eta1-TC4A(O)2(S)2}].  相似文献   

13.
Bi-, tri-, and tetracyclic isoquinoline salts were readily synthesized in excellent yields at room temperature from readily available starting materials after three reaction steps. Aromatic C-H activation was first promoted by sodium acetate with [Cp*MCl2]2 (M = Rh, Ir) at room temperature to form cyclometalated compounds. Dimethylacetylenedicarboxylate was then found to insert into the metal-carbon bonds of the cyclometalated compounds. Finally, the insertion compounds underwent oxidative coupling to form the desired isoquinoline salts and regenerate [Cp*MCl2]2. All of the intermediate compounds following C-H activation, alkyne insertion, and oxidative coupling were fully characterized, including the determination of X-ray structures in several cases, and the results shed light on the overall mechanism. Moreover, it was possible to synthesize the isoquinoline salts from readily available starting materials using one-pot procedures; thus, this work provides a novel, efficient method for metal-mediated synthesis of heterocycles.  相似文献   

14.
Chelating amine and amido complexes of late transition metals are highly valuable bifunctional catalysts in organic synthesis, but complexes of bidentate amine-NHC and amido-NHC ligands are scarce. Hence, we report the reactions of a secondary-amine functionalised imidazolium salt 2a and a primary-amine functionalised imidazolium salt 2b with [(p-cymene)RuCl(2)](2) and [Cp*MCl(2)](2) (M = Rh, Ir). Treating 2a with [Cp*MCl(2)](2) and NaOAc gave the cyclometallated compounds Cp*M(C,C)I (M = Rh, 3; M = Ir, 4), resulting from aromatic C-H activation. In contrast, treating 2b with [(p-cymene)RuCl(2)](2), Ag(2)O and KI gave the amine-NHC complex [(p-cymene)Ru(C,NH(2))I]I (5). The reaction of 2b with [Cp*MCl(2)](2) (M = Rh, Ir), NaO(t)Bu and KI gave the amine-NHC complex [Cp*Rh(NH(2))I]I (6) or the amido-NHC complex Cp*Ir(C,NH)I (7); both protonation states of the Ir complex could be accessed: treating 7 with trifluoroacetic acid gave the amine-NHC complex [Cp*Ir(C,NH(2))I][CF(3)CO(2)] (8). These are the first primary amine- or amido-NHC complexes of Rh and Ir. Solid-state structures of the complexes 3-8 have been determined by single crystal X-ray diffraction. Complexes 5, 6 and 7 are pre-catalysts for the catalytic transfer hydrogenation of acetophenone to 1-phenylethanol, with ruthenium complex 5 demonstrating especially high reactivity.  相似文献   

15.
Reaction of [Cp*IrCl2]2 (1) with dpmp in the presence of KPF6 afforded a binuclear complex [Cp*IrCl(dpmp-P1,P2;P3)IrCl2Cp*](PF6) (2) (dpmp =(Ph2PCH2)2PPh). The mononuclear complex [Cp*IrCl(dpmp-P1,P2)](PF6) (4) was generated by the reaction of [Cp*IrCl2(BDMPP)](BDMPP =PPh[2,6-(MeO)2C6H3]2) with dpmp in the presence of KPF6. These mono- and binuclear complexes have four-membered ring structures with a terminal and a central P atom of the dpmp ligand coordinated to an iridium atom as a bidentate ligand. Since there are two chiral centers at the Ir atom and a central P2 atom, there are two diastereomers that were characterized by spectrometry. Complexes anti-4 and syn-4 reacted with [Cp*RhCl2]2 or [(C6Me6)RuCl2]2, giving the corresponding mixed-metal complexes, anti- and syn- [Cp*IrCl(dppm-P1,P2;P3)MCl2L](PF6) (6: M = Rh, L = Cp*; 7: M = Ru, L = C6Me6). Treatment with AuCl(SC4H8) gave tetranuclear complexes, anti- and syn-8 [[Cp*IrCl(dppm-P1,P2;P3)AuCl]2](PF6)2 bearing an Au-Au bond. Reaction of anti- with PtCl2(cod) generated the trinuclear complex anti-9, anti-[[Cp*IrCl(dppm-P1,P2;P3)]2PtCl2](PF6)2. These reactions proceeded stereospecifically. The P,O-chelated complex syn-[Cp*IrCl(BDMPP-P,O)] (syn-10)(BDMPP-P,O = PPh[2,6-(MeO)2C6H3][2-O-6-(MeO)C6H3]2) reacted with dpmp in the presence of KPF6, generating the corresponding anti-complex as a main product as well as a small amount of syn-complex, [Cp*Ir(BDMPP-P,O)(dppm-P1)](PF6) (11). The reaction proceeded preferentially with inversion. The reaction processes were investigated by PM3 calculation. anti- was treated with MCl2(cod), giving anti-[Cp*Ir(BDMPP-P,O)(dppm-P1;P2,P3)MCl2](PF6)(14: M = Pt; 15: M = Pd), in which the MCl2 moiety coordinated to the two free P atoms of anti-11. The X-ray analyses of syn-2, anti-2, anti-4, anti-8 and anti-11 were performed.  相似文献   

16.
Treatment of [{TiCp*(mu-NH)} 3(mu 3-N)] ( 1; Cp* = eta (5)-C 5Me 5) with yttrium and erbium halide complexes [MCl 3(THF) 3.5] and [MCpCl 2(THF) 3] (Cp = eta (5)-C 5H 5) gives cube-type adducts [Cl 3M{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}] and [CpCl 2M{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}]. An analogous reaction of 1 with [{MCp 2Cl} 2] in toluene affords [Cp 3M(mu-Cl)ClCpM{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}] (M = Y, Er).  相似文献   

17.
The bidentate P,N hybrid ligand 1 allows access for the first time to novel cationic phosphinine‐based RhIII and IrIII complexes, broadening significantly the scope of low‐coordinate aromatic phosphorus heterocycles for potential applications. The coordination chemistry of 1 towards RhIII and IrIII was investigated and compared with the analogous 2,2′‐bipyridine derivative, 2‐(2′‐pyridyl)‐4,6‐diphenylpyridine ( 2 ), which showed significant differences. The molecular structures of [RhCl(Cp*)( 1 )]Cl and [IrCl(Cp*)( 1 )]Cl (Cp*=pentamethylcyclopentadienyl) were determined by means of X‐ray diffraction and confirm the mononuclear nature of the λ3‐phosphinine–RhIII and IrIII complexes. In contrast, a different reactivity and coordination behavior was found for the nitrogen analogue 2 , especially towards RhIII as a bimetallic ion pair [RhCl(Cp*)( 2 )]+[RhCl3(Cp*)]? is formed rather than a mononuclear coordination compound. [RhCl(Cp*)( 1 )]Cl and [IrCl(Cp*)( 1 )]Cl react with water regio‐ and diastereoselectively at the external P?C double bond, leading exclusively to the anti‐addition products [MCl(Cp*)( 1 H ? OH)]Cl as confirmed by X‐ray crystal‐structure determination.  相似文献   

18.
A series of group 6 transition metal half-sandwich complexes with 1,1-dichalcogenide ligands have been prepared by the reactions of Cp*MCl(4)(Cp* = eta(5)-C(5)Me(5); M = Mo, W) with the potassium salt of 2,2-dicyanoethylene-1,1-dithiolate, (KS)(2)C=C(CN)(2) (K(2)-i-mnt), or the analogous seleno compound, (KSe)(2)C=C(CN)(2) (K(2)-i-mns). The reaction of Cp*MCl(4) with (KS)(2)C=C(CN)(2) in a 1:3 molar ratio in CH(3)CN gave rise to K[Cp*M(S(2)C=C(CN)(2))(2)] (M = Mo, 1a, 74%; M = W, 2a, 46%). Under the same conditions, the reaction of Cp*MoCl(4) with 3 equiv of (KSe)(2)C=C(CN)(2) afforded K[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3a) and K[Cp*Mo(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))] (4) in respective yields of 45% and 25%. Cation exchange reactions of 1a, 2a, and 3a with Et(4)NBr resulted in isolation of (Et(4)N)[Cp*Mo(S(2)C=C(CN)(2))(2)] (1b), (Et(4)N)[Cp*W(S(2)C=C(CN)(2))(2)] (2b), and (Et(4)N)[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3b), respectively. Complex 4 crystallized with one THF and one CH(3)CN molecule as a three-dimensional network structure. Inspection of the reaction of Cp*WCl(4) with (KSe)(2)C=C(CN)(2) by ESI-MS revealed the existence of three species in CH(3)CN, [Cp*W(Se(2)C=C(CN)(2))(2)]-, [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-, and [Cp*W(Se(Se(2))C=C(CN)(2))(2)]-, of which [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-(5) was isolated as the main product. Treatment of 2a with 1/4 equiv of S(8) in refluxing THF resulted in sulfur insertion and gave rise to K[Cp*W(S(2)C=C(CN)(2))(S(S(2))C=C(CN)(2))](6), which crystallized with two THF molecules forming a three-dimensional network structure. 6 can also be prepared by refluxing 2a with 1/4 equiv of S(8) in THF. 3a readily added one Se atom upon treatment with 1 mol of Se powder in THF to give 4 in high yield, while the treatment of 3a or 4 with 2 equiv of Na(2)Se in THF led to formation of a dinuclear complex [(Cp*Mo)(2)(mu-Se)(mu-Se(Se(3))C=C(CN)(2))] (7). The structure of 7 consists of two Cp*Mo units bridged by a Se(2-) and a [Se(Se(3))C=C(CN)(2)](2-) ligand in which the triselenido group is arranged in a nearly linear way (163 degrees). The reaction of 2a with 2 equiv of CuBr in CH(3)CN yielded a trinuclear complex [Cp*WCu(2)(mu-Br)(mu(3)-S(2)C=C(CN)(2))(2)] (8), which crystallized with one CH(3)CN and generated a one-dimensional chain polymer through bonding of Cu to the N of the cyano groups.  相似文献   

19.
A simple new route to access heterometallic alkoxo precursors for a wide range of materials is reported. This unique synthetic method comprises elimination of the cyclopentadienyl ring from Cp2MCl2 (M = Ti, Zr) as CpH in the presence of M'(OR)2 (M' = Ca, Mn; OR = OCH2CH2OCH3 or OEt) in an alcohol as a source of protons. In one-pot reactions, we have prepared four different compounds with Ti2Ca4(mu6-O), Cp2Zr2Ca4(mu4-Cl), Zr10Mn10(mu3-O) 14, and Cp3Ti2(mu-OEt)2 motifs. The compounds were characterized by single-crystal X-ray structural analysis and NMR spectroscopy.  相似文献   

20.
Reactions of [[MCl2(Cp*)]2] (1: M=Ir, 2: M=Rh) with bidentate ligands (L) such as 1,4-diisocyano-2,5-dimethylbenzene (a), 1,4-diisocyano-2,3,5,6-tetramethylbenzene (b), pyrazine (c) or 4,4'-dipyridyl (d) gave the corresponding dinuclear complexes [[MCl2(Cp*)]2(L)] (M=Ir: 3a, 3b, 5c, 5d; M=Rh: 4b, 6c, 6d), which were converted into tetranuclear complexes [[M2(mu-Cl)2(Cp*)2]2(L)2](OTf)4 (M=Ir: 7c, 7d, 9a, 9b; M=Rh: 8e, 8d, 10b) on treatment with Ag(OTf). X-ray analyses of 8c and 8d revealed that each of four pentamethylcyclopentadienyl metal moieties was connected by two mu-Cl-bridged atoms and a bidentate ligand to construct a rectangular cavity with the dimensions of 3.7 x 7.0 A for 8c and 3.7 x 11.5 A for 8d. Both the Rh2Cl2 and pyrazine (or 4,4'dipyridyl) ring planes are perpendicular to the Rh4 plane. Treatment of Cl-bridged complexes (7c, 7d, 8e, 8d, 9b, and 10b) with a different ligand (L') resulted in cleavage of the Cl bridges to produce two-dimensional complexes [[MCl(Cp*)]4[(L)-(L')]2](OTf)4 (11ac, 11bc, 11bd, 12bc, and 12bd) with two different ligand "edges". Complex 10b reacted readily with 1,4-diisocyano-2,3,5,6-tetramethylbenzene (b) to give a tetranuclear rhodium(III) complex 12bb. The structure of tetranuclear complexes was confirmed by X-ray analysis of 11bc. Each [MCp*] moiety is surrounded by a Cl atom, isocyanide, and pyrazine (or 4,4'-dipyridyl) and the dimensions of its cavity are 7.0 x 11.6 A.  相似文献   

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