酒石酸铅锆的制备、表征及其燃烧催化作用

以酒石酸、硝酸氧锆和硝酸铅为原料,合成出了双金属盐酒石酸铅锆,采用有机元素分析、X射线荧光光谱和FTIR对其进行了表征。在程序升温条件下,利用TG/DTG、DSC、固相原位反应池/FTIR联用技术,研究了酒石酸铅锆的热行为和热分解机理,描述了酒石酸铅锆的热分解过程,分析得出其最终分解产物为ZrO2、PbO和C。利用螺压工艺制备了含酒石酸铅锆的推进剂样品,研究了酒石酸铅锆对双基系推进剂燃烧性能的影响,分析了其燃烧催化作用。结果表明,酒石酸铅锆对双基系推进剂的燃烧具有良好的催化作用,是一种高效的燃烧催化剂;酒石酸铅锆热分解的最终产物PbO是催化燃烧的主要活性物质,推进剂燃烧过程中形成了氧化铅-铅循环催化体系,而锆和碳则起辅助催化的作用。     

Z型光催化剂Sb2WO6/g-C3N4的制备及光催化性能

通过水热反应合成了Sb₂WO₆改性的g-C₃N₄复合材料(Sb₂WO₆ /g-C₃N₄). 通过X射线衍射(XRD)、 扫描电子显微镜(SEM)、 紫外-可见漫散射反射光谱(UV-Vis DRS)和光致发光光谱(PL)等表征了样品的性质. 结果表明, Sb₂WO₆在g-C₃N₄的表面上生长, 并且复合材料光吸收能力有一定的增强, 光生电子-空穴的重组率降低. 通过罗丹明B(RhB)的光降解评价了Sb₂WO₆/g-C₃N₄复合材料的光催化性能. 结果表明, 模拟日光下Sb₂WO₆质量分数为10%的Sb₂WO₆/g-C₃N₄复合材料在60 min内对RhB的降解率为99.3%, 高于纯g-C₃N₄和Sb₂WO₆. Sb₂WO₆/g-C₃N₄复合材料的这种高度增强的光催化活性主要归因于强的界面相互作用促进了光生电子-空穴分离和迁移. 添加自由基清除剂的实验结果表明, ·O^2-和h⁺是光催化反应中的主要活性物质. Sb₂WO₆/g-C₃N₄复合材料在几个反应周期内表现出优异的稳定性. 根据实验结果提出了一种可能的Z型光催化机理.     

Novel 1,3,5-thiadiazine-2-thione derivatives containing a hydrazide moiety: Design,synthesis and bioactive evaluation against phytopathogenic fungi in vitro and in vivo

A series of novel 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety were designed, synthesized and evaluated for their biological activities against phytopathogenic fungi. The antifungal bioassays indicated that the title compound 5b impressively displayed the obvious selectivity and specificity aganist Rhizoctonia solani (Rs) in vitro and in vivo. The above researches provide a significant reference for the further structural optimization of 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety as potential fungicides.     

Littordial F,a novel phloroglucinol meroterpenoid from the leaves of Psidium littorale

Littordial F (1), a novel meroterpenoid with an unique 6/8/9/4-tetracyclic nucleus, was isolated from the leaves of Psidium littorale. The structure of 1 was established by spectroscopic data, and its absolute configuration was confirmed by computational ¹³C NMR and optical rotation data. Compound 1 exhibited potential cytotoxic activities on A549, B16, and HepG-2 cell lines. A plausible biosynthetic pathway for littordial F was proposed.     

Synthesis,characterization and antimicrobial studies on 13-membered-N6-macrocyclic transition metal complexes containing trimethoprim

Asymmetrical macrocyclic complexes of Mn^II, Co^II, Ni^II, Cu^II and Zn^II have been synthesized by the template process using bis(benzil)ethylenediamine as precursor. Bis(benzil)ethylenediamine reacts with transition metal chlorides and trimethoprim in a 1:1:1 molar ratio in methanol to give several solid metal complexes of the general composition [M(L)X₂] (M = Mn^II, Co^II, Ni^II, Cu^II and Zn^II, L = ligand and X = Cl^?). They were characterized by physicochemical and spectroscopic techniques. Based on analytical, spectral and magnetic moments, all the complexes are identified as distorted octahedral structures. All the complexes are of the [M(L)X₂] type. The shifts of the ν(CN) (azomethine) stretches have been monitored. To find out the donor sites of the ligands, the activity data show that the metal complexes are more potent than the parent ligand. The [M(L)X₂] complexes showed a broad spectrum of antimicrobial activity in vitro against both gram-positive and gram-negative human pathogenic bacterial isolates and the antimicrobial spectrum enhanced only with a combination of metal chlorides and trimethoprim complex. From the results it is imperative that the synthesized macrocyclic [M(L)X₂] complexes exhibit potent broad spectrum antibacterial activity.     

Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.     

Spectral,crystallographic, theoretical and antibacterial studies of palladium(II)/platinum(II) complexes with unsymmetric diphosphine ylides

The reaction of α‐keto‐stabilized diphosphine ylides [Ph₂P(CH₂)_nPPh₂═C(H)C(O)C₆H₄‐p‐CN] (n = 1 (Y¹); n = 2 (Y²)) with dibromo(1,5‐cyclooctadiene) palladium(II)/platinum(II) complexes, [Pd/PtBr₂(cod)], in equimolar ratio gave the new cyclometalated Pd(II) and Pt(II) complexes [Br₂Pd(κ²‐Y¹)] ( 1 ), [Br₂Pt(κ²‐Y¹)] ( 2 ), [Br₂Pd(κ²‐Y²)] ( 3 ) and [Br₂Pt(κ²‐Y²)] ( 4 ). These compounds were screened in a search for novel antibacterial agents and characterized successfully using Fourier transfer infrared and NMR (¹H, ¹³C and ³¹P) spectroscopic methods. Also, the structures of complexes 1 and 2 were characterized using X‐ray crystallography. The results showed that the P,C‐chelated complexes 1 and 2 have structures consisting of five‐membered rings, while 3 and 4 have six‐membered rings, formed by coordination of the ligand through the phosphine group and the ylidic carbon atom to the metal centre. Also, a theoretical study of the structures of complexes 1 – 4 was conducted at the BP86/def2‐SVP level of theory. The nature of metal–ligand bonds in the complexes was investigated using energy decomposition analyses (EDA) and extended transition state combined with natural orbitals for chemical valence analyses. The results of EDA confirmed that the main portions of ΔE_int, about 57–58%, in the complexes are allocated to ΔE_elstat.     

Biomolecular docking,antimicrobial and cytotoxic studies on new bidentate schiff base ligand derived metal (II) complexes

Three new metal complexes [Cu(L)₂] (1), [Co(L)₂] (2) and [Zn(L)₂] (3) have been prepared by the reaction of hydrated salts of metal (II) acetate with new Schiff base ligand HL, [2‐((4‐(dimethylamino)phenylimino)methyl)‐4,6‐di‐t‐butylphenol] and characterized by different physico‐chemical analyses such as elemental analysis, single XRD, ¹H NMR, FTIR and UV–Vis spectroscopic techniques. Their biomolecular docking, antimicrobial and cytotoxicity studies have also been demonstrated. The proposed structure of Schiff base ligand HL and complex 2 are confirmed by Single crystal X‐ray crystallography study. This analysis revealed that metal (II) complexes remain in distorted tetrahedral coordination environments. The electronic properties such as HOMO and LUMO energies are carried out by gaseous phase DFT/B3LYP calculations using Gaussian 09 program. Complex 1 showed a good binding propensity to the DNA and HSA, during the assessment of docking studies. Schiff base ligand HL and its metal (II) complexes, 1–3 screened for their in vitro antimicrobial activities using the disc diffusion method against selected microbes. Complex 1 shows higher antimicrobial activity than complexes 2, 3 and Schiff base ligand HL. According to the results obtained from the cytotoxic studies, Schiff base ligand HL and its metal (II) complexes 1–3 have better cytotoxicity against MCF‐7 cell lines with potency higher than the currently used chemotherapeutic agent cyclophosphamide.     

Platinum (II) N‐heterocyclic carbene complexes: Synthesis,characterization and cytotoxic properties

Platinum (II) complexes bearing N‐heterocyclic carbene (NHC) ligands have been widely used in catalytic chemistry, but there are very few reports of biological properties of this type of complexes. A series of [PtCl₂(NHC)(PEt₃)] complexes were synthesized. The structures of all compounds were characterized by ¹H‐NMR, ¹³C‐NMR, IR and elemental analysis techniques, which supported the proposed structures. The single crystal structures of complexes 1a and 1e were determined. The title complexes show slightly distorted square‐planar coordination around the platinum (II) metal center. The cytotoxic properties of the platinum (II)–NHC complexes have been assessed in various human cancer lines, including cisplatin‐sensitive and resistant cells. IC₅₀ values of these four complexes were determined by the MTS‐based assay on three human cell lines—brain (SHSY5Y), colon (HTC116) and liver (HEP3B). These complexes have been highlighted cancer therapeutic agent with unique structures and functions.     

Synthesis,characterization and cytotoxicity of new 2‐isonicotinoyl‐N‐phenylhydrazine‐1‐carbothioamide and its metal complexes

The reaction of the newly synthesized ligand, 2‐isonicotinoyl‐N‐phenylhydrazine‐1‐carbothioamide (H₃L), with acetate salt of Co (II), Cu (II),Ni (II) and Zn (II) led to isolation of four solid complexes. The ligand and complexes structure elucidation were based on elemental analyses, spectral analyses (IR, UV–Visible, ¹H and¹³C‐NMR, MS and ESR), TGA, molar conductivity and magnetic moments measurements. The results indicated that the ligand exists in the thioketo form, while on coordination to the metal ions; it behaves as mono‐negative bidentate chelate and exists in enol form. The optical band gap measurements of the ligand and its metal complexes are in the range 3.83–4.48 eV indicating their semi‐conducting character. The cytotoxicity examination of H₃L and its Zn (II) complex showed that the ligand have very strong cytotoxicity against both HCT‐116 and HEPG‐2 cell lines while, Zn (II) complex has moderate activity.