Determination of phenolic compounds by MALDI–TOF and essential oil composition by GC–MS during three development stages of Origanum majorana L.

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC–MS. Thirty compounds were detected representing 100% of the total essential oil. p‐Menth‐1‐en‐4‐ol was the major compound (37.15–76.94%) followed by cyclohexanol‐3,3,5 trimethyl (5.41–15.99%) and α‐terpineol (0.94–11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix‐assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.     

Mössbauer Spectra of FePS3-Cobaltocene Intercalation Compound

Abstract

Mössbauer spectra of the FePS₃-cobaltocene intercalation compound were measured in the temperature range of 300K to 10K. The spectra, distinct from those of pure FePS₃, suggest the charge transfer from cobaltocene to Fe-S antibonding orbitals of the FePS₃ host lattice.     

Kinetics of Desolvation of Related Organic Inclusion Compounds

Abstract

This study dealt mainly with the structure-reactivity relationship of selected organic inclusion compounds. The crystal structures of the inclusion compounds of three related hosts, 2,2′–bis(2,7–di-tert-butyl-9–hydroxy-9–fluorenyl)biphenyl, 2,2′–bis (2,7–dichloro-9–hydroxy-9–fluoienyl)biphenyl and 2, 2′–bis(2,7-dibromo-9–hydroxy-9–fluorenyl)biphenyl with 1,4–dioxane (Compound 1), 1,3–dioxane (Compound 2) and 1,3–dioxolane (Compound 3) respectively were elucidated, using single crystal X-ray crystallography. It was found that the guests were either located in channels or constricted channels (cavities), formed by the host framework. The kinetics of desolvation of these compounds were studied and their activation energies were compared.     

Growth of certain harmonic functions in an n-dimensional cone

We give the growth properties of harmonic functions at infinity in a cone, which generalize the results obtained by Siegel-Talvila.     

Alkyl Derivatives of Boehmite Having the Second Stage Structure

Abstract

The reaction of aluminum alkoxide in straight-chain primary alcohols at elevated temperatures yielded the alkyl derivatives of boehmite [AlO(OH)_1-x (OR) _x ], a class of intercalation compound where the guest moieties are covalently bonded to the host boehmite layers. The addition of small amounts of water to the reaction system yielded another phase having a larger basal spacing. XRD, IR, and elemental analysis showed that the products had the boehmite layer structure with the alkyl moieties incorporated between the boehmite layers. IR spectra of the products also exhibited bands due to hydrogen bonding between the boehmite layers. These results suggest that the products are the alkyl derivatives of boehmite having the second stage structure. Because water in the reaction medium facilitated the hydrolysis of intermediate aluminum alkoxides, the product with the second stage structure had smaller alkyl/Al ratio and therefore had smaller basal spacing than that expected from the corresponding first stage product.     

A μ3-OH- bridged two-dimensional zinc(Ⅱ) coordination polymer based on an anthryl ligand：Synthesis, characterization and luminescent properties

A two-dimensional (2D) 3,3,3,4,5,5,6-connected ZnⅡ coordination compound [Zn5(L)2(OH)6]∞ (L=9,10-dioxo-9,10-dihydroanthracene-1,8-dicarboxylate) has been synthesized and characterized by IR, elemental analysis, X-ray powder diffraction and single crystal X-ray diffraction analysis. Moreover, the luminescent properties of the ligand and corresponding compound have been briefly investigated.     

一步法合成的FeOOH/黑磷纳米复合材料协同实现体系优异的析氧性能

通过水热法，在黑磷(BP)纳米片表面生长FeOOH纳米材料，制备出FeOOH/BP纳米复合材料。作为电化学析氧反应(OER)催化剂，该复合材料在20 mA·cm^-2时的过电位仅为191 mV，Tafel斜率为49.9 mV dec^-1；在循环1 000圈后，过电位仅仅增加了3 mV，且循环过程中元素价态不变，表现出优秀的稳定性。纳米FeOOH负载于BP表面，客观上能隔断氧气对BP的氧化，保护BP的载流子传导性能。同时，生长的FeOOH颗粒尺度小，结晶性弱，这有利于丰富其活性位点，增大活性面积。     

Enantioselective Protonation of Cyclic Carbonyl Ylides by Chiral Lewis Acid Assisted Alcohols

Chiral Lewis acid-catalyzed asymmetric alcohol addition reactions to cyclic carbonyl ylides generated from N-(α-diazocarbonyl)-2-oxazolidinones featuring a dual catalytic system are reported. Construction of a chiral quaternary heteroatom-substituted carbon center was accomplished in which the unique heterobicycles were obtained in good yields with high stereoselection. The alcohol adducts were successfully converted to optically active oxazolidine-2,4-diones by hydrolysis. Mechanistic studies by DFT calculations revealed that alcohols could be activated by Lewis acids, enabling enantioselective protonation of the carbonyl ylides.     

3D Uranyl Organic Frameworks Supported by Rigid Octadentate Carboxylate Ligand: Synthesis,Structure Diversity,and Luminescence Properties

Seven three dimensional (3D) uranyl organic frameworks (UOFs), formulated as [NH₄][(UO₂)₃(HTTDS)(H₂O)] ( 1 ), [(UO₂)₄(HTTDS)₂](HIM)₆ ( 2 , IM=imidazole), [(UO₂)₄(TTDS)(H₂O)₂(Phen)₂] ( 3 , Phen=1,10-phenanthroline), [Zn(H₂O)₄]_0.5[(UO₂)₃(HTTDS)(H₂O)₄] ( 4 ), and {(UO₂)₂[Zn(H₂O)₃]₂(TTDS)} ( 5 ), {Zn(UO₂)₂(H₂O)(Dib)_0.5(HDib)(HTTDS)} ( 6 , Dib=1,4-di(1H-imidazol-1-yl)benzene) and [Na]{(UO₂)₄[Cu₃(u₃-OH)(H₂O)₇](TTDS)₂} ( 7 ) have been hydrothermally prepared using a rigid octadentate carboxylate ligand, tetrakis(3,5-dicarboxyphenyl)silicon(H₈TTDS). These UOFs have different 3D self-assembled structures as a function of co-ligands, structure-directing agents and transition metals. The structure of 1 has an infinite ribbon formed by the UO₇ pentagonal bipyramid bridged by carboxylate groups. With further introduction of auxiliary N-donor ligands, different structure of 2 and 3 are formed, in 2 the imidazole serves as space filler, while in 3 the Phen are bound to [UO₂]²⁺ units as co-ligands. The second metal centers were introduced in the syntheses of 4–7 , and in all cases, they are part of the final structures, either as a counterion ( 4 ) or as a component of framework ( 5 − 7 ). Interesting, in 7 , a rare polyoxometalate [Cu₃(μ₃-OH)O₇(O₂CR)₄] cluster was found in the structure. It acts as an inorganic building unit together with the dimer [(UO₂)₂(O₂CR)₄] unit. Those uranyl carboxylates were sufficiently determined by single crystal X-ray diffraction, and their topological structures and luminescence properties were analyzed in detail.     

Efficient production of nanoporous silicon carbide from rice husk at relatively low temperature

Nanoporous silicon carbide with a specific surface area of up to 186.45 m² g⁻¹ has been efficiently synthesized from waste rice husk using a magnesiothermic reduction at 950 °C as a key step. Throughout the entire process, the recovery rates of silicon, potassium and phosphorus from rice husk can reach 88.46, 91.5 and 65.5%, respectively. Turning rice husk waste into a real treasure, this promising method for producing porous SiC protects the environment and brings economic benefits.