Chiral hierarchical molecular nanostructures on two-dimensional surface by controllable trinary self-assembly

The bottom-up fabrication of surface hierarchical nanostructures is of great importance for the development of molecular nanostructures for chiral molecular recognition and enantioselective catalysis. Herein, we report the construction of a series of 2D chiral hierarchical structures by trinary molecular self-assembly with copper phthalocyanine (CuPc), 2,3,7,8,12,13-hexahexyloxy-truxenone (TrO23), and 1,3,5-tris(10-carboxydecyloxy) benzene (TCDB). A series of flower-like chiral hierarchical molecular architectures with increased generations are formed, and the details of these structures are investigated by high resolution scanning tunneling microscopy (STM). The flower-like hierarchical molecular architectures could be described by a unified configuration in which the lobe of each architecture is composed of a different number of triangular shape building units (TBUs). The off-axis edge-to-edge packing of TBUs confers the organizational chirality of the hierarchical assemblies. On the other hand, the TBUs can tile the surface in a vertex-sharing configuration, resulting in the expansion of chiral unit cells, which thereby further modulate the periodicity of chiral voids in the multilevel hierarchical assemblies. The formation of desired hierarchical structures could be controlled through tuning the molar ratio of each component in liquid phase. The results are significant for the design and fabrication of multicomponent chiral hierarchical molecular nanostructures.     

Synthesis, cytotoxicities and DNA-binding affinities of benzofuran-3-ols and their fused analogs

A series of benzofuropyrazoles 2a-i were synthesized in 10-92% from the reaction of 2-aroylbenzofuran-3-ols 1a-i with hydrazine hydrate, and screened for their antitumor activities toward four human solid tumor cell lines, including gastric carcinoma cells MKN45, hepatocellular carcinoma cells HepG2, breast cancer cells MCF-7, and lung cancer cells A549. The results indicated that both compounds 1a-i and 2a-i displayed moderate antitumor activities. Among them, compound 2e exhibited potent inhibitory activity toward all the four tumor cell lines. In addition, compounds 1e and 2e showed strong DNA-binding affinities, and induced an increase in the viscosity of calf-thymus DNA, suggesting that they might act as an intercalator.     

Three New Neolignans and One New Phenylpropanoid from the Leaves and Stems of Toona ciliata var. pubescens

Three new neolignans, (7S,8S,7′E)‐4,9‐dihydroxy‐3,7,3′,9′‐tetramethoxy‐8,4′‐oxyneolign‐7′‐ene ( 1 ), (7R,8S,7′E)‐4, 9‐dihydroxy‐3,7,3′,9′‐tetramethoxy‐8,4′‐oxyneolign‐7′‐ene ( 2 ), (7S,8S,7′E)‐5, 9‐dihydroxy‐3,7,3′,5′,9′‐pentamethoxy‐8,4′‐oxyneolign‐7′‐ene ( 3 ), and one new phenylpropanoid, threo‐5‐hydroxy‐3,7‐dimethoxyphenylpropane‐8,9‐diol ( 4 ), were isolated from the leaves and stems of Toona ciliata var. pubescens. Their structures were determined on the basis of spectroscopic analysis, especially 2D‐NMR, HR‐ESI‐MS, and CD data. The antiproliferative activities of these compounds against four tumor cell lines (A549, Colo 205, QGY‐7703, and LOVO) were also evaluated by MTT (=(3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) method.     

From simple to complex: topological evolution and luminescence variation in a copper(I) pyridylpyrazolate system tuned via second ligating spacers

By systematically varying the geometric length and electronic properties of the second ligating ligands of halogen (Cl(-), Br(-), and I(-)) and pseudohalogen (CN(-), SCN(-), and N(3)(-)) anions, we synthesized 11 isomeric/isostructural copper(I) complexes: [Cu(2)(L3-3)I](n) (1), [Cu(2)(L4-4)Br](n) (2-Br), [Cu(2)(L4-4)Cl](n) (2-Cl), [Cu(2)(L3-4)(CN)](n) (3), [Cu(2)(L3-3)(CN)](n) (4), [Cu(3)(L4-4)(CN)(2)](n) (5), {[Cu(2)(L4-4)Br](2)·CuBr}(n) (6-Br), {[Cu(2)(L4-4)Cl](2)·CuCl}(n) (6-Cl), [Cu(2)(L4-4)(SCN)](n) (7α-SCN), [Cu(2)(L4-4)(SCN)](n) (7β-SCN), and [Cu(2)(L4-4)(N(3))](n) (7α-N(3)). These structures are based on a series of isomeric pyridylpyrazole ligands, namely, 3,5-bis(3-pyridyl)-1H-pyrazole (HL3-3), 3-(3-pyridyl)-5-(4-pyridyl)-1H-pyrazole (HL3-4), and 3,5-bis(4-pyridyl)-1H-pyrazole (HL4-4), and their structural features range from 1-D (1), 2-D (2), and 3-D noninterpenetration (3), to 3-D 2-fold interpenetration (4 and 5), to 3-D self-catenation (6 and 7), exhibiting a trend from simple to complex with dimension expansion and an interpenetrating degree increase. The five most complex structures (6 and 7) with self-catenated networks are based on 2-fold interpenetrated networks linked via appropriate second ligating spacers (Cl(-), Br(-), SCN(-), and N(3)(-)), representing a strategy to construct self-catenated coordination polymers through cross-linking interpenetrated frameworks. Moreover, these complexes exhibit strong photoluminescence, which is mainly ascribed to Cu(I)-related charge transfers (MLCT, MC, and MMLCT) regulated by the electronic properties of halogen or pseudohalogen. The topological evolution and luminescence variation presented in this work open an avenue to understanding the luminescence origin and the structure-property relationship of luminescent coordination polymers.     

Multifunctional NO-delivery vessel derived from aminopropyl-modified mesoporous zeolites

A new strategy, releasing nitric oxide (NO) and adsorbing nitrosamines simultaneously by zeolitic materials in the digestive system, is validated in this paper. Three types of moisture-saturated molecular sieves, HZSM-5 zeolite, mesoporous zeolite, and mesoporous silica MCM-41, are used as NO-delivery vessels in mimic gastric juice after modification of γ-aminopropyltriethoxysilane (APTES). APTES modification dramatically increased the capability of zeolite and mesoporous silica in NO release in acidic solution, because more NO can be adsorbed in the composite and stored in the form of nitrite. Some composites released the NO 10 times more than their parent materials, and synchronously captured the carcinogen nitrosamines in mimic gastric juice. The influences of APTES modification on the porous structure and surface state of zeolite and mesoporous silica were investigated by XRD, N(2) adsorption, and FTIR tests, through which the mesoporous zeolite is proven to be the optimal support. With this hierarchical material a controllable APTES modification is realized in which a lot of aminopropyl groups are grafted in mesopores while the zeolitic structure is maintained, so the resulting sample exhibits a high capability in releasing NO and adsorbing nitrosamines. This investigation provides a clue for elevating the efficiency of zeolites in the application of life science.     

Low-cost and effective phenol and basic dyes trapper derived from the porous silica coated with hydrotalcite gel

Novel low-cost and effective adsorbents of phenol and basic dyes were made by coating amorphous silica with hydrotalcite (HT) gel followed by soaking in alkaline solution, and the surface basic-acidic properties of resulting composites were evaluated by CO(2)-TPD, Hammett indicator method and NH(3)-TPD, respectively. Both BET surface area and microporous surface area of the composites were increased after they were soaked with alkaline solution; meanwhile the center of pore size distribution was changed from 9 to 3-4 nm. These composites efficiently captured phenol in gaseous and liquid phases, superior to mesoporous silica such as MCM-48 or SBA-15 and zeolite NaY, and the equilibrium data of gaseous adsorption could be well fitted to Freundlich model. These modified silicas also exhibited high adsorption capacity forward basic dyes such as crystal violet (CV) and leuco-crystal violet (LCV), reaching the adsorption equilibrium within 1 h and offering a new material for environment protection.     

Controlling the primary particle evolution process towards silica monoliths with tunable hierarchical structure

In order to establish the hierarchical structure in multiple levels on mesoporous silica, this article reports a new strategy to prepare the monolith with the pore configuration in nanometer scale, micro-morphology in micrometer level and macroscopic shape in millimeter or larger grade. These hierarchical monoliths are synthesized in a weak acidic condition by using triblock copolymer P123, hydroxyl carboxylic acid and tetramethyl orthosilicate (TMOS), and the textural properties of the mesostructure can be facilely adjusted by simply controlling the synthesis condition without any additive. During the synthesis, the primary particles can be selectively synthesized as monodispersed sphere, noodle, prism, straight rods with different size or irregular bars, and their connection plus arrangement in 3D directions can be also regulated. Therefore, various textural properties of mesopore are able to be altered including pore size (5.5-10.6 nm), total pore volume (0.48-1.2 cm(3) g(-1)), micropore surface area (47-334 m(2) g(-1)), and pore shape (from 2D or 3D straight channel to plugged channel). Moreover, these monoliths exhibit a considerable mechanical strength; they are also applied in eliminating particulate matters and tobacco special nitrosamines (TSNA) in tobacco smoke, exhibiting various morphology-assisted functions.     

The thermal stabilities of luminescence and microstructures of Eu2+-doped KBaPO4 and NaSrPO4 with β-K2SO4 type structure

Eu(2+)-doped monophosphates NaSrPO(4) and KBaPO(4) with the β-K(2)SO(4) structure were synthesized using the conventional high temperature solid state reaction. The X-ray powder diffraction, photoluminescence excitation, and emission spectra and decay curves were measured. The phosphors can be efficiently excited by UV-visible light from 220 to 430 nm to realize emission in the visible range. The natures of the Eu(2+) emission, e.g., the chromaticity coordinates, the Stokes shifts, and the luminescence absolute quantum efficiencies, were reported. The luminescence quenching temperatures and the thermal activation energies for NaSrPO(4):Eu(2+) and KBaPO(4):Eu(2+) were obtained from the temperature dependent (10-435 K) luminescence intensities and decay curves. KBaPO(4):Eu(2+) presents only one emission center; however, Eu(2+) ions have a "disordered environment" in NaSrPO(4) lattices. The relationship between the luminescence thermal stabilities and the crystal structures was discussed. The crystallographic occupations of rare earth ions doped in these hosts were analyzed by the site-selective emission spectra and the excitation spectra of Eu(3+) ions in the (7)F(0)→(5)D(0) transitions using a pulsed, tunable, and narrow-band dye laser. In KBaPO(4), the Eu(3+) ions could be distributed in the host with a high "ordered state" in only one site in the lattices. However, the multiple site structure of Eu(3+) ions with highly disordered distributions in NaSrPO(4) lattices was suggested.     

Communication: A new approach to dual-basis second-order Møller-Plesset calculations

We describe a hierarchy of approximations (MP2[x]) that allow one to estimate second-order M?ller-Plesset (MP2) energies in a large basis set from small-basis calculations. The most cost-effective approximation, MP2[K], is significantly cheaper than full MP2 but numerical tests on small atoms and molecules indicate that it is nonetheless accurate. We conclude that MP2[K] is an attractive level of theory for large systems.     

Hydrothermal synthesis, structures and magnetic studies of transition metal sulfates containing hydrazine

By employing hydrothermal method, six transition metal sulfates containing hydrazine (N(2)H(4)) have been obtained: [M(SO(4))(2)(N(2)H(5))(2)](n) (M = Mn(1), Co(2), Ni(3)) and [M(N(2)H(4))SO(4)](n) (M = Mn(4), Co(5), Ni(6)). Their crystal structures and magnetic properties have been investigated experimentally and theoretically. Compounds 1-3 consist of one-dimensional sulfate bridged homometallic chains with protonated hydrazine molecule as terminal ligand, and compounds 4-6 are hydrazing-sulfate mixed bridged homometallic three-dimensional frameworks. Compounds 1-6 exhibit antiferromagnetic coupling between M(2+) ions, but their magnetic properties differ at low temperatures because of the different single-ion anisotropy and crystal structures. The magnetostructural correlations and the magnetic coupling mechanism are analyzed by density functional theory calculations (DFT).