基于不同碱基含量的[FeFe]-氢化酶模型化合物功能化聚合物的合成与表征

将含二炔基的[2Fe2S]模型化合物[Fe₂(μ-SCH₂C≡CH)₂(CO)₆](A)和双叠氮单体2,6-(N₃CH₂)Py(B, Py=吡啶)与含碱性基团的双炔单体(2-PyCH₂)N(CH₂C≡CH)₂(C, Py=吡啶)通过“点击反应”以不同比例进行共聚,得到了6种含不同碱基量的[FeFe]-氢化酶模型化合物功能聚合物Polymer-1~Polymer-6.通过红外光谱、硫元素分析、热重、扫描电镜和电化学对这些聚合物进行了表征.红外光谱和电化学研究表明二铁六羰基单元A以二铁五羰基的形式存在于聚合物中.在共聚过程中,增加单体C的含量能显著改变聚合物的形貌和增加其在有机溶剂中的溶解度,同时热稳定性也有所增加.这些聚合物在含有醋酸的DMF介质中催化质子还原的行为表明,通过单体C引入的碱性基团所形成的次级配位环境对二铁中心的催化性能有显著影响.     

以2-(1-吡唑基甲基)吡啶类化合物为配体的羰基钼、钨衍生物的合成及结构

合成了2-[1-(3-叔丁基)吡唑基甲基]吡啶(CH2(Py)(3-ButPz)),并研究了羰基钼(钨)与该配体及其类似物2-(1-吡唑基甲基)吡啶(CH2(Py)(Pz))和2-[1-(3,5-二甲基)吡唑基甲基]吡啶(CH2(Py)(3,5-Me2Pz))的反应,合成了6个含双齿螯合的2-(1-吡唑基甲基)吡啶类配体的四羰基金属衍生物CH2(Py)(3-ButPz)M(CO)4,CH2(Py)(Pz)M(CO)4和CH2(Py)(3,5-Me2Pz)M(CO)4(M=Mo或W)。当用SnCl4处理CH2(Py)(3,5-Me2Pz)M(CO)4时,Sn-Cl键对金属中心发生氧化加成得到2个杂双核金属有机化合物CH2(Py)(3,5-Me2Pz)M(CO)3(Cl)SnCl3。所有新化合物均通过了红外和核磁的表征,CH2(Py)(3-ButPz)W(CO)4和CH2(Py)(3,5-Me2Pz)W(CO)3(Cl)SnCl3的结构还得到了X-射线单晶衍射的确证。用循环伏安法测定了四羰基金属衍生物的电化学性质。     

四面体三核原子簇合物的合成

本文报道以卤代的卡拜化合物[Mo(≡CC~6H~5)Br(CO)~2(PY)~2](Py=吡啶)(1)为原料,分别与八羰基二钴、九羰基二铁和十羰基二锰反应,制得未见报道的三核原子簇合物[Co~2Mo(μ~3-CC~6H~5)Br(CO)~8(Ph)~2](2)、[Fe~2Mo(μ~3-CC~6H~5)(μ-CO)Br(CO)~8(Py)~2](3)和[Mn~2Mo(μ~3-CC~6H~5)Br(CO)~1~0(Py)~2](4)。但1与含钼钼三重键的化合物[(C~5H~5)~2Mo~2-(CO)~4]的加成反应未能实现。通过元素分析、IR、^1H和^1^3CNMR推断了2～4的结构。     

新型二茂铁炔基苯胺化合物及其钴羰基簇合物的合成及其电化学性质

以乙炔基双二茂铁丙烷和对碘苯胺为原料,合成了一个新的二茂铁乙炔基化合物[FcC(CH3)2Fc'-C≡CC6H4-NH2(1)];以1为配体,与Co2(CO)8反应合成了一个新的炔桥钴羰基簇合物{[FcC(CH3)2Fc'-C≡CC6H4-NH2]Co2(CO)6},其结构经1H NMR,13C NMR,IR和MS表征。利用循环伏安法对1的电化学性质进行了初步研究,实验结果表明:扫描速率为30 mV·s-1时,1具有两个较为明显的还原峰Epc1(0.279 V)和Epc2(0.496 V)。     

钼的含硫配位体络合物对于偶氮类及炔类化合物的络合和活化作用

本文改进了Jownt合成MoO[S_2P(OEt)_2]_2的方法,还发现了两个新的合成方法。合成了新加合物MoO(S_2CNEt_2)_2·(Ac)(Ac=CH≡CCH_2OH,CH≡CCH_2OEt,CH≡CCH_2C1,CH≡CCH_2Br,HOCH_2C≡CCH_2OH)和MoO[S_2P(OEt)_2]_2·(EtO_2CN=NCO_2Et)。研究了Mo_2O_3[S_2P(OEt)_2]_4·、MoO(S_2P(OEt)_2)_2、Mo_2O_3(S_2CNEt_2)_4、MoO(S_2CNEt_2)_2,Mo_2O_3(S_2COEt)_4(以下分别简写为P(5)、P(4)、N(5)、N(4),O(5))络合和活化炔类化合物的性能,并发现与炔键络合的是Mo(Ⅳ)络合物,且含硫配位体的供电子能力愈强,Mo(Ⅳ)络合物络合和活化炔键的能力亦愈强。     

含氟炔酮和炔醛类化合物的质谱研究

本文报道18个含氟炔酮和炔醛类化合物的质谱及其解析结果。在含氟炔酮中,当全氟烷基联结于羰基碳或炔碳上时,质谱的断裂规律有所不同,观察到苯基或取代苯基或全氟烷基重排脱CO的碎片离子,在含氟炔醛中,出现脱CO和脱氟或部分氟碳烷基的碎片的离子(CF2C≡CH)[+]。另外亦出现脱氟或部分氟碳烷基的碎片离子(CF2C≡CCHO)[+],此碎片离子的相对丰度次序为:n-C3F7>C2F5>CF3。在化合物5～15中,有氟重排离子(M-R1R2+F)[+]出现。     

含碳硼烷半夹心型钴硫16电子化合物与二炔烃的反应性研究

含双硫取代碳硼烷二齿配体的半夹心型钴16电子化合物CpCo[S2C2(B10H10)](Co16e)分别与1,4-二乙炔基苯(L1)、(S)-2,2′-二乙酰氧基-6,6′-二乙炔基-1,1′-联萘(L2)、2-溴-5-乙炔基噻吩(L3)和2,5-二乙炔基噻吩(L4)反应,分别得到18电子单核化合物CpCo(S2C2B10H9)(H2CCPhC≡CH)(1),CpCo(S2C2B10H9)[H2CC(C24H16O4)C≡CH](2),CpCo(S2C2B10H9)[H2CC(C4H2S)Br](3),和CpCo(S2C2B10H9)[H2CC(C4H2S)C≡CH](4)。化合物1～4的结构中都发生了金属诱导B-H键活化并生成了新的C-B键。在Co16e与L4的反应中,还得到了两分子炔烃以头对头二聚插入到金属中心的18电子化合物CpCo(S2C2B10H9)[HC≡C(C4H2S)C=CH-CH=C(C4H2S)C≡CH](5)。上述化合物通过NMR、IR、MS、元素分析等方法进行表征。     

含手性三联苯腰接型液晶聚乙炔的合成及其“甲壳效应”

设计、合成了一种新单体,并由[Rh(nbd)Cl]2/Et3N(nbd =2,5-降冰片二烯)催化聚合反应制备了一种具有较高相对分子质量(质均相对分子质量为30300)的含手性三联苯液晶聚乙炔PAM3OCO(TPh)(OR*)2{一[(CH=C(CH2)3OCO-terphenyl(OR*)2]n—,R*=(S)-2-甲基丁基}.由于手性基团和三联苯液晶基元的引入,单体具有互变手性近晶C相,而聚合物则呈现互变的手性近晶A相液晶行为.三联苯液晶基元以重心位置连接于聚合物主链并围绕主链所产生的“甲壳效应”赋予了聚合物很高的热稳定性(356℃)、发光性能和聚集诱导增强发光特性.其薄膜状态下的发光强度明显大于其在稀溶液状态下的发光强度,且内量子效率和外量子效率分别为0.214和0.023.紫外光激发下,聚合物在液晶状态下的发光强度明显优于溶液和薄膜状态,并且发光谱带发生了红移.     

基于非血红素铁模型配合物[FeⅣ(O)(N4Py)]2+的新型N杂环卡宾配合物的理论设计

基于四价非血红素铁模型配合物[FeⅣ(O)(N4Py)]2+, 通过理论计算设计出一种新型N杂环卡宾配合物[FeⅣ(O)(N4Py)]2+. 采用密度泛函理论B3LYP方法, 计算了[FeⅣ(O)(N4Py)]2+的几何结构和电子结构, 并研究了[FeⅣ(O)(N4Py)]2+使环己烷C-H键羟基化的反应机理. 结果表明, [FeⅣ(O)(N4Py)]2+的五重态能量比基态三重态能量高约5.7 kJ/mol, 故五重态几乎不能参与反应. 赤道方向的配位基N杂环卡宾(NHC)对FeO单元的σ-贡献要大于N4Py的贡献, 而它的空间位阻效应也大于N4Py, 因此2+的稳定性强于[FeⅣ(O)(N4Py)]2+. [FeⅣ(O)(N4Py)]2+的三重态的反应能垒比[FeⅣ(O)(N4Py)]2+的三重态反应能垒高2.0 kJ/mol, 且为单态反应, 所以[FeⅣ(O)(N4Py)]2+的反应活性要高于[FeⅣ(O)(N4Py)]2+.     

N,N-二乙基硫代氨基甲酰硫基团(S_2CNEt_2)为假卤原子转移的原子转移自由基聚合新体系

综述了原子转移自由基聚合 (ATRP)中 ,以N ,N 二乙基硫代氨基甲酰硫基团 (S2 CNEt2 )转移实现活性聚合、控制聚合物结构的 4种新方法 :非卤化物 ,N ,N 二乙基二硫代氨基甲酸亚铜 [Cu(S2 CNEt2 ) ]催化甲基丙烯酸甲酯 (MMA)的正向ATRP ;2 ,2′ 联吡啶存在的条件下 ,过氧化苯甲酰 (BPO)与Cu(S2 CNEt2 )的氧化还原反应控制MMA的本体反向ATRP;同时含可转移卤原子、基团的氯化二乙基二硫代氨基甲酸铜 [Cu(S2 CNEt2 ) Cl]成功地用于偶氮二异丁腈或BPO引发的乙烯类单体反向ATRP.假卤原子S2 CNEt2 转移的ATRP得到窄分布的精确结构聚合物分子链ω 端含有光敏基团S2 CNEt2 ,可引发乙烯类单体的常温光聚合 ,实现ATRP与光聚合相结合制备嵌段共聚物     

Asymmetric catalysis as a method for the synthesis of chiral organophosphorus compounds

This review discusses methods for the metallo-, organo- and biocatalytic asymmetric synthesis of chiral organophosphorus compounds with many applications in stereoselective synthesis with references to updated literature reports as well as the author’s original research. Asymmetric catalytic hydrogenation and reduction with chiral organometallic complexes, together with actively used asymmetric organocatalytic versions of various reactions enable us to synthesize chiral organophosphonates and phosphinates with high enantioselectivity and purity. Asymmetric catalysis is also an effective tool to realize some classic reactions of phosphorus chemistry in a stereospecific manner.     

Natural and artificial light-harvesting systems utilizing the functions of carotenoids

Carotenoids are essential pigments in natural photosynthesis. They absorb in the blue–green region of the solar spectrum and transfer the absorbed energy to (bacterio-)chlorophylls, and so expand the wavelength range of light that is able to drive photosynthesis. This process is an example of singlet–singlet energy transfer and so carotenoids serve to enhance the overall efficiency of photosynthetic light reactions. Carotenoids also act to protect photosynthetic organisms from the harmful effects of excess exposure to light. In this case, triplet–triplet energy transfer from (bacterio-)chlorophyll to carotenoid plays a key role in this photoprotective reaction. In the light-harvesting pigment–protein complexes from purple photosynthetic bacteria and chlorophytes, carotenoids have an additional role, namely the structural stabilization of those complexes. In this article we review what is currently known about how carotenoids discharge these functions. The molecular architecture of photosynthetic systems will be outlined to provide a basis from which to describe the photochemistry of carotenoids, which underlies most of their important functions in photosynthesis. Then, the possibility to utilize the functions of carotenoids in artificial photosynthetic light-harvesting systems will be discussed. Some examples of the model systems are introduced.     

Study of intramolecular aminolysis in peptides containing N-alkylamino acids at position 2

Many peptides and proteins, containing N^α-alkylamino acids (including proline) at the second position, are prone to intramolecular aminolysis (IA) with elimination of N-terminal dipeptide sequence as 2,5-diketopiperazines (DKP). We synthesized a series of short peptides, containing N-alkylamino acids at position 2, and studied their stability in the presence of acetic acid and amines. The presence of side chains in the second and the third amino acid residues and alkylation at N^α of the third amino acid residue slowed down IA. N^α-Alkyl residue in the first amino acid residue impeded IA only in peptides, containing three or more residues. Side chains of the first amino acids did not affect significantly the cleavage rates. Acetic acid promoted IA more strongly than aqueous ammonia, while tertiary amines were less effective. Peptides with methionine-S-oxide residues were more labile than the unoxidized analogs, suggesting intramolecular assistance of the S-oxide group in aminolysis. Surprisingly, intermediate compounds of the formula Boc–Met-MeXaa-Sar–NHR underwent rapid cleavage (endopeptolysis) upon attempted acidolytic deprotection.     

Use of grapevine cell cultures for the production of phytostilbenes of cosmetic interest

Plant cell cultures constitute pesticide-free sources for obtaining plant secondary metabolites or plant extracts. Additionally, they do not contain any fungal contaminants, mycotoxins or heavy metals providing to the consumer potential health benefits and justifying the development of this technology at an industrial scale. Significant production levels of these secondary metabolites can be obtained through the use of elicitors, which activate plant defense mechanisms. Resveratrol, a well-known grapevine polyphenolic compound which possesses potent antioxidant and antiaging activities as well as a protective action on skin, is a good example of such plant secondary metabolites. Resveratrol and its oligomeric derivatives are used by several companies of cosmetic products but their extraction from vine stems and similar vegetal sources remains difficult. Therefore grapevine cell suspensions could represent interesting systems for the large-scale bioproduction of those compounds. Here we present an update of the methods used for the production of phytostilbenes by using grapevine cell cultures and the results obtained.     

Synthesis,characterization, powder XRD and antimicrobial-antioxidant activity evaluation of trivalent transition metal macrocyclic complexes

The in vitro antimicrobial and antioxidant activities of metal complexes derived from 1,8-diaminonaphthalene and 5,5-dimethylcyclohexane-1,3-dione were evaluated. The complexes were synthesized by template method in the presence of trivalent metal salts, resulting in the formation of tetraaza macrocyclic complexes of the type [M (C₃₆H₃₆N₄) X] X₂, where M = Cr(III), Fe(III) and X = Cl^–, NO₃^–, CH₃COO^–. The synthesized complexes were characterized with the aid of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, electronic, IR, mass and powder XRD studies. Based on various studies, a five-coordinated square pyramidal geometry was proposed for these complexes. The X-ray diffraction studies suggest a monoclinic crystal system for the complexes.     

Photochemical tuning of materials: A click chemistry perspective

Light driven reactions are perpetual tools for environment sustainability. As an external trigger, most of the photon driven reactions are stereoselective, precise, efficient and offer temporal control for biomolecules. The photoinduced reactions are key to unique molecular transformations that include click and unclick reactions. Since 2003, there has been an exponential rise research papers citing light driven reactions. This review considers the light promoted development and modification of reactions that fall under the criteria of ‘Click’ series of transformations. The review lays emphasis on the light induced biochemical, carbohydrate modification, surface labelling, bioconjugation, polymer modification, dendrimer synthesis, [4 + 2] and [2 + 2] reaction, thiol–ene/yne coupling, Cu assisted cycloaddition, strain-promoted azide alkyne cycloaddition (SPAAC), nitro photoclick and photounclick reactions published in last one and half decade. This series of photoclick reactions use short wavelength radiations and are instant, clean, and near to perfect for transforming reactants to the desirable products.     

Identification of potential inhibitor and enzyme-inhibitor complex on trypanothione reductase to control Chagas disease

Chagas is a parasitic disease with major threat to public health due to its resistance against commonly available drugs. Trypanothione reductase (TryR) is the key enzyme to develop this disease. Though this enzyme is well thought-out as potential drug target, the accurate structure of enzyme-inhibitor complex is required to design a potential inhibitor which is less available for TryR. In this research, we aimed to investigate the advanced drug over the available existing drugs by designing inhibitors as well as to identify a new enzyme-inhibitor complex that may act as a template for drug design. A set of analogues were designed from a known inhibitor Quinacrine Mustard (QUM) to identify the effective inhibitor against this enzyme. Further, the pharmacoinformatics elucidation and structural properties of designed inhibitor proposed effective drug candidates against Chagas disease. Molecular docking study suggests that a designed inhibitor has higher binding affinity in both crystal and modeled TryR and also poses similar interacting residues as of crystal TryR-QUM complex structure. The comparative studies based on in silico prediction proposed an enzyme-inhibitor complex which could be effective to control the disease activity. So our in silico analysis based on TryR built model, Pharmacophore and docking analysis might play an important role for the development of novel therapy for Chagas disease. But both animal model experiments and clinical trials must be done to confirm the efficacy of the therapy.     

Interrelationship between total volatile organic compounds emissions,structure and properties of natural rubber/polycaprolactone bio-blends cross-linked with peroxides

Natural rubber/polycaprolactone (NR/PCL) bio-based blends with different organic peroxides were prepared using an internal batch mixer and subsequently cross-linked at 170 °C. Two types of commonly used organic peroxides, dicumyl peroxide and di(tert-butylperoxyisopropyl)benzene peroxide, were applied as free-radical initiator. Cross-linking efficiency of NR/PCL blends were investigated using oscillating disc rheometer measurements, followed by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Total volatile organic compounds (TVOCs) emissions were determined using headspace analysis integrated with gas chromatography with flame ionization detector. Determined TVOCs emissions varying in range 21.6–52.1 μg/g and generally value of this parameter decreased with increasing content of PCL phase in studied blends or with application of more efficient di(tert-butylperoxyisopropyl)benzene peroxide as cross-linking agent. It was found that increasing of TVOCs parameter indicated deterioration of mechanical properties of NR/PCL blends, which corresponded with the changes in chemical structure and thermal properties of cross-linked NR/PCL. This confirms that evaluation of TVOCs parameter is interesting alternative for “conventional methods” to characterization of the studied bio-based blends.     

Computational analysis for the determination of deleterious nsSNPs in human MTHFD1 gene

Single nucleotide polymorphisms (SNPs) are the most common genetic polymorphisms and play a major role in many inherited diseases. Methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) is one of the enzymes involved in folate metabolism. In the present study, the functional and structural consequences of nsSNPs of human MTHFD1 gene was analyzed using various computational tools like SIFT, PolyPhen2, PANTHER, PROVEAN, SNAP2, nsSNPAnalyzer, PhD-SNP, SNPs&GO, I-Mutant, MuPro, ConSurf, InterPro, NCBI Conserved Domain Search tool, ModPred, SPARKS-X, RAMPAGE, FT Site and PyMol. Out of 327 nsSNPs form human MTHFD1 gene, total 45 SNPs were predicted as functionally most significant SNPs, among which 17 were highly conserved and functional, 17 were highly conserved and structural residues. Among 45 most significant SNPs, 15 were predicted to be involved in post translational modifications. The p.Gly165Arg may interfere in homodimer interface formation. The p.Asn439Lys and p.Asp445Asn may interfere in binding interactions of MTHFD1 protein with cesium cation and potassium. The two SNPs (p.Asp562Gly and p.Gly637Cys) might interfere in interactions of MTHFD1 with ligand.     

Comparative study of kinetics isomerization of substituted polyacetylene (Cl,F and I): Ab initio and DFT calculations

Ab initio and DFT methods were used to investigate the interconversions of substituted polyacetylene conformers C₁₀H₆X₆ (X=F, Cl and I) in the vapour phase. The rates of this geometrical isomerization have been calculated and the Arrhenius parameters evaluated. In the case of unsubstituted polyacetylene as the reference, the B3LYP Arrhenius parameters obtained are A₁=2.99 × 10¹⁷ s^–1 and E_a=17.30 kcal mol^–1. The values of the equilibrium constant for the reaction have also been determined at various temperatures between 300 and 500 K and the value of the energies change calculated. The results also suggest that the straightforward kinetics characterizing the majority of substituted polyacetylene isomerizations above 300 K. The isomerization energies are positive and the barrier heights ΔE_barrier are expected to be sensitive for the magnitude of halogens effects. According to geometries features the Cis → Trans isomerization in the gas phase occurs by a rotational mechanism.