Thermal Bevaviour of the Coordination Compound [Mn(urea)6](NO3)2·2H2O

Thermoanalytical, mass spectrometric and X-ray diffraction data were associated with a reliable assignation of the thermal transformations of the coordination compound [Mn(urea)₆](NO₃)₂·2H₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of urea on synchronous fluorescence spectra and electrochemical behaviour of cytochrome

The changes of the synchronous fluorescence spectra and the electrochemical behaviour of cytochrome c with the urea concentration are studied. It has been found that with the increase of urea concentration, there occur sequentially the deaggregation of cytochrome c molecules, the increase of exposure extent of the heme group to the solvent, the disruption of Fe-S bond of the heme group and the change in the electrochemical behaviour of cytochrome c. It is suggested that the reason why the electrochemical reaction of cytochrome c is irreversible is that cytochrome c molecules exist in the concentrated solution as oligomers which are electrochemically inactive.     

Small Molecule Soluble Epoxide Hydrolase Inhibitors in Multitarget and Combination Therapies for Inflammation and Cancer

The enzyme soluble epoxide hydrolase (sEH) plays a central role in metabolism of bioactive lipid signaling molecules. The substrate-specific hydrolase activity of sEH converts epoxyeicosatrienoic acids (EETs) to less bioactive dihydroxyeicosatrienoic acids. EETs exhibit anti-inflammatory, analgesic, antihypertensive, cardio-protective and organ-protective properties. Accordingly, sEH inhibition is a promising therapeutic strategy for addressing a variety of diseases. In this review, we describe small molecule architectures that have been commonly deployed as sEH inhibitors with respect to angiogenesis, inflammation and cancer. We juxtapose commonly used synthetic scaffolds and natural products within the paradigm of a multitarget approach for addressing inflammation and inflammation induced carcinogenesis. Structural insights from the inhibitor complexes and novel strategies for development of sEH-based multitarget inhibitors are also presented. While sEH inhibition is likely to suppress inflammation-induced carcinogenesis, it can also lead to enhanced angiogenesis via increased EET concentrations. In this regard, sEH inhibitors in combination chemotherapy are described. Urea and amide-based architectures feature prominently across multitarget inhibition and combination chemotherapy applications of sEH inhibitors.     

含吡啶二脲配体汞(II)、镉(II)配合物的合成及其晶体结构

以2,2′-二氨基二苯醚和4-吡啶异氰酸酯反应合成了含吡啶二脲配体(L),并分别与HgCl_2和Cd(ClO_4)2进行了配位反应,得到2个配位聚合物{[Hg(L)Cl_2]·2DMF}_n(1)和{[Cd(L)_2(H_2O)_2](ClO_4)_2·4DMF·2H_2O·2CH_3OH}_n(2),采用1H NMR、MS、FTIR和元素分析等对化合物L进行了表征。通过X射线单晶衍射技术测定了配体及2个配合物的单晶结构,结构解析表明,2个配合物均为一维链状结构。进一步考察了2个配合物的热稳定性及其对甲醇蒸气的吸附性能。     

Radical Anions from Urea‐type Carbonyls: Radical Cyclizations and Cyclization Cascades

Radical anions generated from urea carbonyls by reductive electron transfer are exploited in carbon–carbon bond formation. New radical cyclizations of urea radical anions deliver complex nitrogen heterocycles and, depending upon the proton source used in the reactions, a chemoselective switch between reaction pathways can deliver two heterobicyclic scaffolds. A computational study has been used to investigate the selectivity of the urea radical processes. Furthermore, radical cyclization cascades involving urea radical anions deliver unusual spirocyclic aminal architectures.     

Thermodynamic characterisation of RNAase a in the presence of urea and GuHCl

It is presented a study concerning the influence of guanidinium chloride (GuHCl) and urea on thermal stability of Bovine Pancreatic Ribonuclease A (RNAase A) at differentpH values. As expected, at increasing the denaturant concentration, the protein thermostability decreases. This is shown by a decrease of both the thermodynamic parameters, temperature and heat effect, characterising the denaturation process. In order to analyse the calorimetric curves we adopt a statistical thermodynamic approach. The individual one-dimensional DSC profiles have been expanded into another dimension by varying the GuHCl concentration, so that a heat capacity surface is defined for eachpH. By means of the ICARUS program, developed in our laboratory, we accomplish a two dimensional deconvolution of the experimental data linking the binding equilibrium to the denaturation process. This analysis provides a well founded and complete statistical thermodynamic characterisation of denaturation process of RNAase A in the presence of GuHCl and allows to calculate the thermodynamic parameters associated to the binding of denaturant molecule.     

Thermodynamics ofN,N,N-octylpentyldimethyl-ammonium chloride in water-urea mixtures

Specific conductivities, densities, heat capacities, and enthalpies of dilution at 25‡C were measured forN,N,N-octylpentyldimethylammonium chloride (OPAC) in water-urea mixtures at various urea concentrations m_u as functions of the surfactant concentration m_s. From conductivity data, the cmc and the degree of the counterion dissociation Β of the OPAC micelles were calculated. The cmc increases linearly with increasingm _u while Βvs. m_u is a smooth concave curve. From the experimental thermodynamic data, the apparentY _Φ and partialY ₂ molar properties (volumes, heat capacities, and relative enthalpies) are derived as functions of m_u andm _s . The effect of urea on the dependences of the different properties on m_s are discussed. From data in the premicellar region the standard partial molar volumesV ₂ ⁰ and heat capacitiesC _p2 ⁰ were evaluated. It was observed thatV ₂ ⁰ increases linearly withm _u whileC _p2 ⁰ decreases. The properties of OPAC in the dispersed and micellized forms at the cmc were obtained and, therefore, the thermodynamic functions of micellization were calculated on the basis of the pseudo-phase transition model.     

Structure–property relationships of anionic poly(urethane–urea) dispersion cross-linked with partially methylated melamine formaldehyde

An anionic poly(urethane–urea) dispersion (PUD) was cross-linked with different amount of partially methylated melamine formaldehyde (PMMF). The isothermal curing behavior was observed by a rigid-body pendulum rheometer. The test results showed that cure response of PUD cross-linked with PMMF was a function of the concentration of PMMF. Also, PMMF self-condensation could take place during the curing process. In this experiment, the anionic poly(urethane–urea) dispersion has a large number of >N–H cross-linking or branching sites in urethane and urea groups per molecule that allow a large number of PMMF to couple into elastic PUD backbone to form branched structure with partial cross-linking. The dynamic mechanical properties of PUD cross-linked with PMMF were affected by the concentration of PMMF. It was further shown that the tensile properties were strongly influenced by the concentration of PMMF and curing temperature.     

N-5-(1H-1,2,4-三唑基）-N'-芳甲酰基脲的合成与生物活性

以5-氨基-1H-1，2，4-三唑-3-羧酸与酰基异氰酸酯反应，合成了15个新的N- 5-（1H-1，2，4-三唑基）-N'-芳甲酰基脲，用核磁共振氢谱、红外光谱和元素分 析确证了其结构，并进行了室内生物活性测试。生测试验证明部分酰基脲类化合物 具有良好的植物生长调节活性，其中N-5（3-羧基-1，2，4-三唑基）-N'-o-氯苯甲 酰基脲、N-5-（3-羧基-1，2，4-三唑基）-N'-o-溴苯甲酰基脲和N-5-(3-羧基-1， 2，4-三唑基）-N'-p(或m)-甲基苯甲酰基脲具有优良的生长素活性。     

新型手性不对称脲分子钳受体的设计合成

以芳杂环为隔离基, 手性不对称脲为手臂设计合成了一类新型的分子钳, 其结构经¹H NMR, IR, MS和元素分析所确证, 并且考察了其对卤素阴离子C1^—, Br^—, I^—的识别性能.