Solution chemistry of uranyl ion with iminodiacetate and oxydiacetate: A combined NMR/EXAFS and potentiometry/calorimetry study

The solution chemistry of uranyl ion with iminodiacetate (IDA) and oxydiacetate (ODA) was investigated using NMR and EXAFS spectroscopies, potentiometry, and calorimetry. From the NMR and EXAFS data and depending on stoichiometry and pH, three types of metal:ligand complex were identified in solution in the pH range 3-7: 1:1 and 1:2 monomers; a 2:2 dimer. From NMR and EXAFS data for the IDA system and previous studies, we propose the three complex types are [UO(2)(IDA)(H(2)O)(2)], [UO(2)(IDA)(2)](2)(-), and [(UO(2))(2)(IDA)(2)(mu-OH)(2)](2)(-). From EXAFS spectroscopy, similar 1:1, 2:2, and 1:2 complexes are found for the ODA system, although (13)C NMR spectroscopy was not a useful probe in this system. For the 1:1 and 1:2 complexes in solution, EXAFS spectroscopy is ambiguous because the data can be fitted with either a long U-N/O(ether) value (ca. 2.9 A) suggesting 1,7-coordination of the ligand or a U-C interaction at a similar distance, consistent with terminal bidentate coordination. However, the NMR data of the IDA system suggest that 1,7-coordination is the more likely. The stability constants of the three complexes were determined by potentiometric titrations; the log beta values are 9.90 +/-, 16.42 +/-, and 10.80 +/- for the 1:1, 1:2, and 2:2 uranyl-IDA complexes, respectively, and 5.77 +/-, 7.84 +/-, and 4.29 +/- for the 1:1, 1:2, and 2:2 uranyl-ODA complexes, respectively. The thermodynamic constants for the complexes were calculated from calorimetric titrations; the enthalpy changes (kJ mol(-)(1)) and entropy changes (J K(-)(1) mol(-)(1)) of complexation for the 1:1, 1:2, and 2:2 complexes respectively are the following. IDA: 12 +/- 2, 230 +/- 8; 8 +/- 2, 151 +/- 9; -33 +/- 3, -283 +/- 11. ODA: 26 +/- 2, 198 +/- 12; 20 +/- 2, 106 +/- 8; -24 +/- 2; -219 +/- 8.     

Synthesis, variable temperature NMR investigations and solid state characterization of novel octafluorofluorene compounds

The preparation of a number of new 9-substituted octafluorofluorene derivatives, solution NMR studies, and the first examples of solid state structures of octafluorofluorenes [1,2,3,4,5,6,7,8-octafluorofluorene, C₁₃H₂F₈, 1; 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenylfluorene, C₁₉HF₁₃, 8; 1,1′,2,2′,3,3′,4,4′,5,5′,6,6′,7,7′,8,8′-hexadecafluoro-9,9′-bifluorenyl, C₂₆H₂F₁₆, 11] are reported. Variable temperature ¹⁹F NMR investigations have been performed on the 9-aryl substituted compounds 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenyl-9-hydroxyfluorene, C₁₉HF₁₃O, 4, 1,2,3,4,5,6,7,8-octafluoro-9-(nonafluoro-4′-biphenylyl)-9-hydroxyfluorene, C₂₅HF₁₇O, 5, and 8, and the energetic barriers to rotation of the aryl have been determined. A lower rotational barrier is observed for compound 4 with respect to compound 8, while 5 does not show fluxional behaviour below 338 K. The results of the variable temperature experiments performed on 8 have been rationalized by 2D NMR studies, and compared to the solid state data resulting from the X-ray structural analysis.     

Synthesis and characterization of an amethyrin-uranyl complex displaying aromatic character

Abstract

The reaction between amethyrin and non-aqueous uranyl silylamide (UO₂[N(SiMe₃)₂]₂) under anaerobic conditions affords a bench-stable uranyl complex. UV–vis spectroscopy, cyclic voltammetry, as well as proton NMR spectroscopic analyses provide support for the conclusion that all six pyrrole subunits participate in coordination of the uranyl dication and that, upon complexation, the amethyrin-core undergoes a 2-electron oxidation to yield a formal 22 π-electron aromatic species.     

Synthesis, characterization, and reactivity of a uranyl beta-diketiminate complex

Addition of 1 equiv of Li(Ar2nacnac) (Ar2nacnac = (2,6-(i)Pr2C6H3)NC(Me)CHC(Me)N(2,6-(i)Pr2C6H3)) to an Et2O suspension of UO2Cl2(THF)3 generates the uranyl dimer [UO2(Ar2nacnac)Cl]2 (1) in good yield. A second species can be isolated in low yield from the reaction mixtures of 1, namely [Li(OEt2)2][UO2(Ar2nacnac)Cl2] (2). The structures of both 1 and 2 have been confirmed by X-ray crystallography. Complex 1 reacts with Ph3PO to generate UO2(Ar2nacnac)Cl(Ph3PO) (3). In addition, 1 reacts with AgOTf and either 1 equiv of DPPMO2 or 2 equiv of Ph2MePO to provide [UO2(Ar2nacnac)(DPPMO2)][OTf] (4) and [UO2(Ar2nacnac)(Ph2MePO)2][OTf] (5), respectively. Both 4 and 5 have been fully characterized, including analysis by X-ray crystallography and cyclic voltammetry. Reduction of 4 with Cp2Co provides UO2(Ar2nacnac)(CH{Ph2PO}2) (6), a uranyl(VI) complex that is generated by the formal loss of H* from the DPPMO2 ligand. Labeling studies have been performed in an attempt to elucidate the mechanism of hydrogen loss. In contrast, reduction of 5 with Cp2Co provides UO2(Ar2nacnac)(Ph2MePO)2 (7), a rare example of a uranyl(V) complex. As expected, the solid-state molecular structure of 7 reveals slightly longer U-O(oxo) bond lengths relative to 5. Furthermore, complex 7 can be converted back into 5 by oxidation with AgOTf in toluene.     

硫杂蒽酮的合成和表征

为了寻求合成硫杂蒽酮的高效新方法,以2,2′-二硫代二苯甲酸和苯酚为原料,硫酸为溶剂和催化剂,考察了沸石分子筛、Al2O3和P2O5、温度、原料的物质的量之比、反应时间对反应收率的影响,确定了最佳反应条件,推测了可能的反应过程;进而以2,2′-二硫代二苯甲酸和相应的苯衍生物为原料,在H2SO4-P2O5体系中于最佳反应条件下制备了13个硫杂蒽酮类化合物,并利用柱色谱分离以及红外光谱与核磁共振谱对产物进行表征.结果表明,在反应体系中引入P2O5有利于促进反应的完成;最佳反应条件为:温度70℃、2,2′-二硫代二苯甲酸/苯衍生物物质的量之比1∶6、反应时间6h.邻苯二酚与二硫代水杨酸的反应产物——化合物11(a)和11(b)为同分异构体.     

Synthesis and characterization of organogallium-antimony compounds

The simple Lewis acid–base adduct Me₃Ga←Sb(SiMe₃)₃ (1) was prepared by the reaction of Me₃Ga and Sb(SiMe₃)₃. Dehalosilylation reaction between Me₂GaCl and Sb(SiMe₃)₃ in 1:1 mol ratio yields the trimeric [Me₂GaSb(SiMe₃)₂]₃ (2). 1 and 2 were fully characterized by mass and NMR spectroscopy. In addition, the solid state structure of compound 2 was determined by single crystal X-ray diffraction.     

Preparation and characterization of uranyl complexes with phosphonate ligands

The preparation, spectroscopic characterization and thermal stability of neutral complexes of uranyl ion, UO₂ ²⁺, with phosphonate ligands, such as diphenylphosphonic acid (DPhP), diphenyl phosphate (DPhPO) and phenylphosphonic acid (PhP) are described. The complexes were prepared by a reaction of hydrated uranyl nitrate with appropriate ligands in methanolic solution. The ligands studied and their uranyl complexes were characterized using thermogravimetric and elemental analyses, ESI-MS, IR and UV–Vis absorption and luminescence spectroscopy as well as luminescence lifetime measurements. Compositions of the products obtained dependent on the ligands used: DPhP and DPhPO form UO₂L₂ type of complexes, whereas PhP forms UO₂L complex. Based on TG and DTG curves a thermal stability of the complexes was determined. The complexes UO₂PhP·2H₂O and UO₂(DPhPO)₂ undergo one-step decomposition, while UO₂PhP · 2H₂O is decomposed in a two-step process. The thermal stability of anhydrous uranyl complexes increases in the series: DPhPO < PhP < DPhP. Obtained IR spectra indicate bonding of P–OH groups with uranyl ion. The main fluorescence emission bands and the lifetimes of these complexes were determined. The complex of DPhP shows a green uranyl luminescence, while the uranyl emission of the UO₂PhP and UO₂(DPhPO)₂ complexes is considerably weaker.     

Synthesis and characterization of new cyclotriphosphazene compounds

In the present study, spiro (1a), dispiro (1b, 2, 3), per-substituted spermine-bridged (6–9) and dispiroansa spermine (10) derivatives of cyclotriphosphazene have been synthesized. The structures of the novel compounds (1b, 6–10) have been characterized by elemental analysis, FTIR, mass spectrometry, ¹H and ³¹P NMR spectroscopy. The molecular structures of 1b, 2, 8, and 10 were determined by single crystal X-ray crystallography. In order to investigate the anti-tumour properties of the newly synthesized cyclotriphosphazene derivatives, in vitro cytotoxic activity test (MTT assay) has been performed using HT-29 (human colon adenocarcinoma) and Hep2 (human epidermoid larynx carcinoma) cell lines. The result of the MTT assay showed that while compound 1a has cytotoxic effect on both Hep2 and HT-29 cell lines, compound 3 has only cytotoxic effect towards the Hep 2 cells.     

Synthesis and characterization of macrocyclic compounds with a hydroxyl functional group

A novel [1+1] Schiff-base macrocyclic compound 3 has been synthesized from precursor 1, 1,3-bis(2'-formylphenoxy)-2-propanol, and precursor 2, resorcinol-bis(4-aminophenyl)ether, via condensation and cyclizaction using Ba2+ as template. The macrocycle 3 was further reduced giving saturated macrocycle 4. The structures of 3 and 4 were characterized by elemental analysis, 1H NMR, IR, and MS spectra, and their structures were determined via single crystal X-ray diffraction studies. X-ray diffraction analysis revealed that the macrocyclic compound 3 has a folded conformation, and the corresponding reduced product 4 adopts a twisted and folded conformation due to its flexible nature.     

Synthesis,characterization and thermodynamic data of compounds with NZP structure

Data on synthesis, thermal behavior and thermodynamic properties for the NZP phosphates NaMe₂(PO₄)₃ and Na₅Me(PO₄)₃ (Me=Ti, Zr, Hf) are reported. The compounds were synthesized by sol-gel method and solid-state reactions and characterized by X-ray powder diffraction, IR spectroscopy, electron microprobe and chemical analysis. Their thermal behavior was studied by the DTA measurements. The heat capacities of the phosphates were measured between temperatures 7 and 650 K. The fractal dimensions for the phosphates were calculated. The obtained thermodynamic characteristics of these phosphates and also literature data for the compounds of NZP type structure are summarized.     

Synthesis and characterization of new crown-type compounds with 4-pyrone Units

We report here the syntheses and characterization of new crown-type compounds 8 and 9 incorporated with one and two 4-pyrone units. The reaction of compound 3 with 1,5-bis(2-hydroxyphenoxy)-3-oxapentane or catechol gave the desired molecules 8 and 9 in 65% and 25% yields, respectively. Compound 3 resulted from 1 by Wohl-Ziegler bromination in small amounts and could be separated from five bromination by-products by column chromatography. For example, 8 binds K⁺ and a pyrylium salt 11 (single crystal X-ray structure analysis) can also be prepared starting from 3 by treatment of the latter with perchloric acid in the presence of acetonitrile.     

过氧杂多阴离子型层柱化合物的合成、表征及催化活性

通过离子交换法,将含Zr过渡金属离子1,3取代钨硅、钨磷过氧杂多酸盐嵌入Zn2Al类水滑石中,获得了层柱化合物,并用XRD,IR,UV等手段对产物的结构进行了表征.结果表明过氧杂多阴离子进入水滑石层间后,水滑石的层间距从0.92增大到1.47 nm,且过氧链没被破坏.层柱化合物在酯化反应中显示优良的催化性能.     

含硅二烃基锡(Ⅳ)邻菲咯啉配合物的合成及结构表征

1980年,Crowe等人首次报道了六配位有机锡(Ⅳ)配合物R2SnX2L2(R=烷基或苯基;X=F,C l,Br,I或NCS;L为含O或N的有机配体)对P388淋巴白血病细胞有抑制活性[1]。以后人们合成许多二烃基锡配合物,并对基作了广泛的研究[2,3]。结果表明,二烃基锡化合物的抗肿瘤活性主要取决于烃基,混合二烃基锡化合物毒性较高,使它们的应用受到一定的限制。在药物分子中,某个碳原子被硅取代,称为硅药(Sila-drug),其特点是能降低毒性,有时也能提高药效[6]。因此,开展对含硅有机锡化合物进行研究,对于探讨分子中引入硅原子后对有机锡化合物性质的影响有一定的…     

Synthesis and characterization of MDI-butanediol urethane model compounds

Hard-segment model compounds containing one to five 4,4′-methylene bis(p-phenylisocyanate) (MDI) units extended with 1,4-butanediol (BD) were synthesized. The ends of the model compounds were reacted with ethanol. The melting point (T_m) of the model compounds increased with the number of MDI units to an extrapolated value of 299°C for the homopolymer using Flory's equation accounting for chain end defects. The ΔH of fusion was 5.3 kcal/mol. Intrinsic viscosity measurements in DMA solutions revealed a Mark Houwink exponent of 1.43 suggesting that the hard-segment model compounds are rodlike in solution. Wide-angle X-ray diffraction showed that the percentage of hard-segment crystallinity decreased as the oligomer length increased. Infrared spectroscopy studies showed that the distribution of hydrogen bond distances between C?O and NH groups became broader with increasing segment length.     

哒嗪酮类阿拉伯糖苷化合物的合成与表征

近年来科学家和营养学家就阿拉伯糖(Arabinose)在肠道内对糖类代谢的作用作了大量的研究工作:临床试验表明阿拉伯糖对蔗糖的代谢转化具有阻断作用,使其在减肥、控制糖尿病等方面的应用前景看好.     

卟啉-5-氟尿嘧啶衍生物的合成与表征

5-氟尿嘧啶(5-Fu)是一种作用于DNA合成期的抗恶性肿瘤药物,主要用于消化道癌和乳腺癌,是治疗胃癌的首选药.但它的一大缺点是服药有效剂量与中毒量相近,在杀死癌细胞的同时正常细胞损伤也较严重.     

Synthesis and characterization of some new dimesogenic compounds

We have synthesized four different types of dimesogenic compounds involving the cholesteryl moiety as one of the mesogenic constituents, and have investigated their liquid crystalline properties. The molecular structures of these dimesogens have been confirmed by spectral analyses; they exhibit a rich polymorphism, as revealed by optical microscopic and differential scanning calorimetric observations. The studies show that the mesomorphic behaviour is sensitive to the nature of the terminal alkyl chains, and to the structure of the 'second mesogen' that is attached to the cholesteryl unit through a polymethylene spacer.