骨架金属原子对Keggin阴离子电子结构和物化性质的研究

使用第一原理密度泛函理论中的离散变分方法(DFT-DVM)对(PM~1~2O~4~0)^n^-(M=Mo,W,V),(PMo~9W~3O~4~0)^3^-,(PMo~9V~3O~4~0)^6^-五种Keggin结构杂多阴离子进行了电子结构计算,讨论了骨架金属原子对Keggin结构杂多阴离子的电荷分布、成键作用、热稳定性、氧化还原性等的影响。结果表明,骨架金属原子对Keggin阴离子的电荷分布和成键作用均有一定的影响,以Mo,W,V作骨架金属原子的Keggin阴离子(PM~1~2O~4~0)^n^-的热稳定性顺序为:(PW~1~2O~4~0)~3^->(PMo~1~2O~4~0)^3^->(PV~1~2O~4~0)^1^5^-。提出了判断杂多阴离子氧化性强弱的两因素法---脱出晶格氧的难易程度和LUMO轨道电负性,并根据两因素法得到氧化性强弱顺序为:(PV~1~2O~4~0)^1^5^->(PMo~1~2O~4~0)^3^->(PW~1~2O~4~0)~3^-。同时,讨论了当(PMo~1~2O~4~0)~3^-中的Mo部分被W和V取代后,即(PMo~9W~3O~4~0)^3^-,(PMo~9V~3O~4~0)^6^-,其中取代原子对电子结构的影响,结果表明,W取代使整个阴离子的稳定性增强,但氧化性减弱,V取代,使稳定性减弱,但氧化性增强。     

骨架金属原子对Keggin阴离子电子结构和物化性质的研究

使用第一原理密度泛函理论中的离散变分方法(DFT-DVM)对(PM~1~2O~4~0)^n^-(M=Mo,W,V),(PMo~9W~3O~4~0)^3^-,(PMo~9V~3O~4~0)^6^-五种Keggin结构杂多阴离子进行了电子结构计算,讨论了骨架金属原子对Keggin结构杂多阴离子的电荷分布、成键作用、热稳定性、氧化还原性等的影响。结果表明,骨架金属原子对Keggin阴离子的电荷分布和成键作用均有一定的影响,以Mo,W,V作骨架金属原子的Keggin阴离子(PM~1~2O~4~0)^n^-的热稳定性顺序为:(PW~1~2O~4~0)~3^->(PMo~1~2O~4~0)^3^->(PV~1~2O~4~0)^1^5^-。提出了判断杂多阴离子氧化性强弱的两因素法---脱出晶格氧的难易程度和LUMO轨道电负性,并根据两因素法得到氧化性强弱顺序为:(PV~1~2O~4~0)^1^5^->(PMo~1~2O~4~0)^3^->(PW~1~2O~4~0)~3^-。同时,讨论了当(PMo~1~2O~4~0)~3^-中的Mo部分被W和V取代后,即(PMo~9W~3O~4~0)^3^-,(PMo~9V~3O~4~0)^6^-,其中取代原子对电子结构的影响,结果表明,W取代使整个阴离子的稳定性增强,但氧化性减弱,V取代,使稳定性减弱,但氧化性增强。     

中心原子对Keggin结构杂多阴离子的电子结构和催化性质的影响

使用SCC-DV-Xα方法计算了Keggin结构的杂多阴离子(SiMo12O40)^4^-,(GeMo12O40)^4^-, (AsMo12O40)^3^-的电子结构, 并与文献对(PMo12O40)^3^-的计算结果作了对比分析。讨论了中心原子对Keggin结构的杂多阴离子的电子结构和催化性质的影响。结果表明, 中心原子对Keggin结构杂多阴离子的电子云、静电势、总态密度的分布影响不明显; 但中心原子不同, 前线轨道HOMO, LUMO的组成有一定差异。四种阴离子的εLUMO和εFermi的相对大小关系为:(AsMo12O40)^3^->(PMo12-O40)^3^->(GeMo12O40)^4^->(SiMo12O40)^4^-, 其氧化能力和催化活性也具有相同的顺序。(XMO12-O40)^n^-(X=Si, Ge, P)中端氧Ot, 桥氧Ob, Mo以及X都具有催化活性, 在催化反应中都可能成为催化活性中心,而(AsMo12O40)^3^-中仅有As和Ob可作为催化活性中心。     

Dawson结构钼磷酸的合成与表征

合成了H_6P_2Mo_(18)O_(62)杂多酸及其四丁基铵盐和四丁基鏻盐,用IR、~(31)P NMR、GV等手段核查其纯度并研究了热稳定性、酸性和氧化还原性。结果表明,Dawson结构钼磷酸较Keggin结构钼磷酸有更强的氧化性。     

双帽Keggin型杂多阴离子[PM12O40(VO)2]n-(M=Mo,n=5; M=V, n=9)的离散变分方法研究

使用密度泛函理论的离散变分方法(DFT-DVM)研究了双帽Keggin型杂多阴离子[PM12O40(VO)2]n-(M=Mo, n=5; M=V, n=9),即[PMo12O40(VO)2]5- (a)和[PV12O40(VO)2]9- (b)的电子结构,讨论了双帽的形成对Keggin型杂多阴离子的电子结构和催化性质的影响,并与其Keggin型杂多阴离子(PM12O40)n-(M=Mo, n=3; M=V, n=15)的计算结果进行了对比分析,计算结果表明,双帽的形成对Keggin型杂多阴离子的电子结构产生了很大的影响,因而它们在催化活性上可能会表现出较大的差异.     

双帽Keggin型杂多阴离子[PM12O40(VO)2]n-(M=Mo,n=5;M=V,n=9)的离散变分方法研究

使用密度泛函理论的离散变分方法(DFT-DVM)研究了双帽Keggin型杂多阴离子[PM₁₂O₄₀(VO)₂]^n--(M=Mo,n=5; M=V,n=9),即[PMo₁₂O₄₀(VO)₂]^5- (a)和[PV₁₂O₄₀(VO)₂]^9- (b)的电子结构,讨论了双帽的形成对Keggin型杂多阴离子的电子结构和催化性质的影响,并与其Keggin型杂多阴离子(PM₁₂O₄₀)_n-(M=Mo,n=3; M=V,n=15)的计算结果进行了对比分析,计算结果表明,双帽的形成对Keggin型杂多阴离子的电子结构产生了很大的影响,因而它们在催化活性上可能会表现出较大的差异.     

Keggin结构和Dawson结构杂多酸(盐)及其衍生物的氧化还原性质研究

本文系统研究了Keggin结构和Dawson结构两大系列几十个杂多酸(盐)及其钒和稀土衍生物LnHSiMo_(12),SiMo_(12-n)V_n,M_(1.5)PMo_(12),PMo(12-n)V_n,PW_(12-n)V_n,Ln(PMon_(11))_2,Sm(XMon_(11))_2和P_2Mo_(13-n)V_n等在溶液中的氧化还原性质,得到了它们的氧化序。发现Keggin结构杂多阴离子及其稀土衍生物还原电势与nq~2线性相关(n,q分别为中心离子的主量子数和电荷)。根据静电模型对两大系列杂多化合物的氧化还原规律性给予了合理说明。     

杂多化合物的合成与结构性能研究的近代发展

本文对含有各种新组分的新合成的杂多化合物物种进行了综述,并概述了Keggin型阴离子的酸性、氧化性和稳定性的一些规律性与结构的关系问题。     

Dawson结构硫钼杂多阴离子的电子结构

使用第一原理密度泛函理论中的离散变分方法（DFT-DVM）对（S2Mo18O62）4-的电子结构进行了理论计算,并与Keggin结构（SMo12O40）2-的电子结构作了比较分析,结果表明,（S2Mo18O62）中的电子离域地分布在整个阴离子骨架中,但极位和赤道位原子的电荷分布有明显差异。端氧与Mo之间的键均较强,中心氧与Mo之间形成的键最弱。（S2Mo18O62）4-的化学行为的活性中心是赤道位钼Moe、极位端氧Opt、极位共顶桥氧Opea、赤道位端氧Oet和赤道位共边桥氧Oeb。与（SMo12O40）2-相比,（S2Mo18O62）4-的稳定性和氧化性均较弱。但在两种类型的硫钼杂多阴离子中,Mo对其氧化性的产生起了重要的作用。     

两种结构钼磷酸的催化氧化行为

考察了Dawson与Keggin结构钼磷酸的催化氧化行为,并与结构特性进行了关联,结果发现,Dawson结构的杂多酸对氧化脱氢及插入氧反应均有更高的活性。     

六次甲基四胺与H_nXMo_(12)O_(40)·mH_2O(X=P,Si,Ge)电荷转移盐的合成、表征及二阶非线性光学性质

合成了由六次甲基四胺与Ｈ３ＰＭｏ１２Ｏ４０·ｎＨ２Ｏ,Ｈ４ＳｉＭｏ１２Ｏ４０·ｎＨ２Ｏ 和Ｈ４ＧｅＭｏ１２ Ｏ４０·ｎＨ２Ｏ 形成的具有二阶非线性光学性质的电荷转移盐,并由元素分析,红外光谱,电子光谱进行了表征。结果表明六次甲基四胺分子中有两个Ｎ 原子参与盐的形成,固体中阴阳离子之间存在强的相互作用;非线性光学性质研究表明,三种电荷转移盐的倍频效应分别为ＫＤＰ和０．０２ ,０ ．１１ 和０．０６ 倍。     

杂多酸(盐)及单缺位磷钨杂多化合物在醇类氧化反应中的催化活性

在相转移条件下,研究了杂多化合物在苄醇,环己醇氧化反应中的催化活性.六种Keggin结构杂多酸的催化活性按GeMo~12(H~4GeMo~12O~40的简写,其余类推,PW~12,PMo~12,SiMo~12,GeW~12,SiW~12顺序下降,杂多酸中的质子可分别被其它阳离逐渐取代而达到酸性修饰. H~3PW~12O~40随着其质子逐步被Na^+取代,酸性下降,催化活性大大提高;杂多酸(盐)的催化活性随体系pH值的改变将发生奇妙剧烈的变化;单缺位杂多化合物显示出较饱和杂多酸(盐)更高催化活性.溶剂对催化活性有明显影响.     

Hydrogen-bonded assemblies of two-electron reduced mixed-valence [XMo12O40] (X = P and Si) with p-phenylenediamines

Hydrogen-bonded assemblies of the two-electron reduced mixed-valence Keggin clusters [PMo(12)O(40)](5-) and [SiMo(12)O(40)](6-) were obtained by the one-pot electron-transfer reactions between p-phenylenediamine (PPD) or 2,3,5,6-tetramethyl-PPD (TMPPD) (donors) and H(+)(3)[PMo(12)O(40)](3-) or H(+)(4)[SiMo(12)O(40)](4-) (acceptors) in CH(3)CN. The redox states of the [PMo(12)O(40)](5-) and [SiMo(12)O(40)](6-) clusters were confirmed by the redox titrations and electronic absorption measurements. In (HPPD(+))(3)(H(+))(2)[PMo(12)O(40)](5-)(CH(3)CN)(3-6) (1), the N-H ~ O hydrogen-bonded interactions between the monoprotonated HPPD(+) (or diprotonated H2PPD(2+)) and the [PMo(12)O(40)](5-) resulted in a windmill-like assembly and hydrophilic one-dimensional channels are formed with a cross-sectional area of 0.065 nm(2), and these are filled by the CH(3)CN molecules. Also, the CH(3)CN molecules in salt 1 were removed by immersing the single crystals of 1 into H(2)O, CH(3)OH, and C(2)H(5)OH solvents. In the compound, (HTMPPD(+))(6)[SiMo(12)O(40)](6-)(CH(3)CN)(6) (2), the N-H ~ O hydrogen-bonded interactions between the monoprotonated HTMPPD(+) molecules and the [SiMo(12)O(40)](6-) formed a "Saturn-ring"-like assembly. Each Saturn-ring was arranged into an hexagonally packed array via hydrogen-bonded and π-stacking interactions of HTMPPD(+), while the CH(3)CN solvent present in salt 2 are only found in the zero-dimensional isolated cavities.     

Zeolite ionic crystals assembled through direct incorporation of polyoxometalate clusters within 3D metal-organic frameworks

Polyoxometalate-based metal-organic frameworks {[Gd(dpdo)(4)(H(2)O)(3)](PMo(12)O(40))(H(2)O)(2)CH(3)CN}(n) (2), {[Dy(dpdo)(4)(H(2)O)(3)](PMo(12)O(40))(H(2)O)(20CH(3)CN}(n) (3), {[Gd(dpdo)(4)(H(2)O)(3)](H(3)O)(SiMo(12)O(40))(dpdo)(0.5)(CH(3)CN)(0.5) (H(2)O)(3)}(n) (4), {[Ho(dpdo)(4)(H(2)O)(3)](H(3)O)(SiMo(12)O(40))(dpdo)(0.5)(CH(3)CN)(0.5)(H(2)O)(3)}(n) (5), {[Ni(dpdo)(2)(CH(3)CN) (H(2)O)(2)](2)(SiMo(12)O(40))(H(2)O)(2)}(n) (6), and {[Ni(dpdo)(3)](4)(PW(12)O(40))(3)[H(H(2)O)(27)(CH(3)CN)(12)]}(n) (7) (where dpdo is 4,4'-bipyridine-N,N'-dioxide) were constructed via self-assembly by embedding Keggin-type polyanions within the intercrystalline voids as guests or pillars. Compounds 2 and 3 are isomorphic and exhibit three-dimensional (3D) noninterwoven 64 frameworks with distorted-honeycomb cavities occupied by the polyanions. Compounds 4 and 5 are comprised of 3D noninterwoven frameworks formed by linking the adjacent folded sheets through hydrogen bonds and pi-pi stacking interactions relative to the free isolated dpdo ligand. Compound 6 is a pillar-layered framework with the [SiMo(12)O(40)](4-) anions located on the square voids of the two-dimensional bilayer sheets formed by the dpdo ligands and nickel(II) ions. Compound 7 is a 3D metal-organic framework formed by nickel(II) and 4,4'-bipyridine-N,N'-dioxide with the globular Keggin-structure [PW(12)O(4)](3-) anion as the template. A large protonated water cluster H(+)(H(2)O)(27) is trapped and stabilized within the well-modulated cavity.     

杂多酸离子液体催化燃油萃取氧化脱硫性能研究

本文首次将一系列含有不同酸性咪唑阳离子和不同杂多酸阴离子的杂多酸离子液体[C4mim]3PW12O40、[COOH-Cmim] 3PW12O40、[SO3H-C3mim]3PW12O40、[SO3H-C3mim]3PMo12O40和[SO3H-C3mim]4 SiW12O40作为催化剂,乙腈为萃取剂,H2O2为氧化剂,用于催化含二苯并噻吩、苯并噻吩及噻吩模型油的萃取氧化脱硫研究中.实验结果显示,杂多酸离子液体催化燃油脱硫性能不仅与阳离子的酸性强弱有关,而且与阴离子结构密切相关.阳离子的催化活性顺序为:[SO3H-C3mim]+＞[COOH-Cmim]+＞[C4mim]+;阴离子的催化活性顺序为PW12O403-＞ PMo12O403-＞ SiW12O404-.其中[SO3H-C3 mim]3 PW12O40催化活性最高,在60℃反应40min的条件下,二苯并噻吩的转化率约为100％,催化不同硫化物的转化率为:二苯并噻吩＞苯并噻吩＞噻吩.此外,该杂多酸离子液体循环使用5次催化活性仅略有下降.     

Electrochemical synthesis and structural and physical characterization of one- and two-electron-reduced forms of [SMo12O40]2-

Isolation of a soluble [NHex4]+ salt has allowed a detailed electrochemical study of the anion alpha-[SMo12O40]2- to be undertaken. Four reversible one-electron-reduction processes are observed in CH2Cl2 solution. Controlled potential electrolysis led to isolation of tetraalkylammonium salts of the one-electron-reduced anion alpha-[SMo12O40]3- and the two-electron-reduced anion alpha-[SMo12O40].4- [SMo12O40]3- is stable to disproportionation in dry solvents (Kdis = 10(-7.4). EPR and magnetic susceptibility data indicate that [SMo12O40]3- is a simple paramagnet (S = 1/2) while [SMo12O40]4- is paramagnetic with the mu eff values decreasing at low temperatures. Solutions of the two-electron-reduced species are EPR silent, but microcrystalline powders show very weak signals. The crystal structure of alpha-[NBu4]3[SMo12O40] has been determined (triclinic P1; a = 13.840(3) A; b = 15.587(4) A; c = 19.370(3) A; alpha = 94.82(2) degrees; beta = 93.10(1) degrees; gamma = 91.05(2) degrees; Z = 2). There is disorder around the C2 axis of the central SO4(2-) tetrahedron. In the presence of aqueous HClO4 (0.045 M) in thf/H2O or MeCN/H2O (98/2 v/v), [SMo12O40]2- exhibits five two-electron-reduction processes. Under these conditions, [SMo12O40]3- protonates and disproportionates into [SMo12O40]2- and the (2e-, 2H+)-reduced anion [H2SMo12O40]2-.     

Synthesis,Properties and Crystal Structure of A New 12-Molybdogermanic Salt of Lanthanum Coordinated to N -Methyl-2-Pyrrolidone

A new compound [La(NMP) 4 (H 2 O) 4 ][HGeMo 12 O 40 ]·2NMP·3H 2 O (NMP = N -methyl-2-pyrrolidone), 1 , was synthesized and characterized. The compound crystallizes in the monoclinic space group P 2 1 / c with a = 17.3428(4), b = 18.3258(5), c = 23.0387(7) Å, g = 107.088(1)°, V = 6998.9(3) Å 3 and Z = 4. The structure was characterized crystallographically with final R 1 = 0.0589, wR 2 = 0.1596. The crystal structure contains [GeMo 12 O 40 ] 4 m anions combining with [La(NMP) 4 (H 2 O) 4 ] 3+ cations through hydrogen bonds. The La 3+ ion exhibits eight-coordination with four water molecules and four carbonyl oxygen atoms of the organic ligands. Hydrogen bonds are formed between [GeMo 12 O 40 ] 4 m anions and coordinated water molecules, coordinating to water molecules. The anti-tumor activity of 1 was estimated against Hela and P c -3m cancer cells.     

A microwave-assisted and heteropolyacids-catalysed cyclocondensation reaction for the synthesis of 4(3H)-quinazolinones

We have investigated a microwave-assisted synthesis of 4(3H)-quinazolinones by condensation of anthranilic acid, orthoesters (or formic acid) and substituted anilines,using Keggin-type heteropolyacids (H(3)PW(12)O(40).13H(2)O, H(4)SiW(12)O(40).13H(2)O,H(4)SiMo(12)O(40).13H(2)O or H(3)PMo(12)O(40).13H(2)O) as catalysts. We found that the the use of H(3)PW(12)O(40).13H(2)O acid coupled to microwave irradiation allows a solvent-free, rapid (approximately 13min) and high-yielding reaction.     

杂多酸对二甘醇脱水环化反应的催化作用

研究了杂多酸对二甘醇脱水环化的催化作用。结果表明,磷钨酸,硅钨酸,硅钼酸具有较高的催化活性,而磷钼酸的催化活性较低。采用ＴＧ,ＩＲ,ＧＣ－ＭＳ,电导等测试技术,对正丁胺酸性,杂多阴离子碱度,还原特性的测定及对产物结构的分析。