Novel and Efficient Synthesis of DHPMs Catalyzed by di‐DACH‐Pyridylamide Ligands

Di‐DACH‐pyridylamide ligands, symmetrical bridged bis‐Schiff base, and spiro pyrrolizines as catalysts in the synthesis of dihydropyrimidinethiones (DHPMs) using the Biginelli reaction is first reported. This new protocol has the advantages of environmental friendliness, short reaction time, excellent yields, and simple post‐treatment procedure. A series of DHPMs were obtained in high yields (up to 98%) in only 6 h. Moreover, based on the optimized condition, a novel Biginelli‐like reaction was first developed.     

Pincer‐Type Platinum(II) Complexes Containing N‐Heterocyclic Carbene (NHC) Ligand: Structures,Photophysical and Anion‐Binding Properties,and Anticancer Activities

Two classes of pincer‐type Pt^II complexes containing tridentate N‐donor ligands ( 1 – 8 ) or C‐deprotonated N^C^N ligands derived from 1,3‐di(2‐pyridyl)benzene ( 10 – 13 ) and auxiliary N‐heterocyclic carbene (NHC) ligand were synthesized. [Pt(trpy)(NHC)]²⁺ complexes 1 – 5 display green phosphorescence in CH₂Cl₂ (Φ: 1.1–5.3 %; τ: 0.3–1.0 μs) at room temperature. Moderate‐to‐intense emissions are observed for 1 – 7 in glassy solutions at 77 K and for 1 – 6 in the solid state. The [Pt(N^C^N)(NHC)]⁺ complexes 10 – 13 display strong green phosphorescence with quantum yields up to 65 % in CHCl₃. The reactions of 1 with a wide variety of anions were examined in various solvents. The tridentate N‐donor ligand of 1 undergoes displacement reaction with CN^? in protic solvents. Similar displacement of the N^C^N ligand by CN^? has been observed for 10 , leading to a luminescence “switch‐off” response. The water‐soluble 7 containing anthracenyl‐functionalized NHC ligand acts as a light “switch‐on” sensor for the detection of CN^? ion with high selectivity. The in vitro cytotoxicity of the Pt^II complexes towards HeLa cells has been evaluated. Complex 12 showed high cytotoxicity with IC₅₀ value of 0.46 μM , whereas 1 – 4 and 6 – 8 are less cytotoxic. The cellular localization of the strongly luminescent complex 12 traced by using emission microscopy revealed that it mainly localizes in the cytoplasmic structures rather than in the nucleus. This complex can induce mitochondria dysfunction and subsequent cell death.     

Ba3V2S4O3: A Mott Insulating Frustrated Quasi‐One‐Dimensional S=1 Magnet

Through a solid‐state reaction, a practically phase pure powder of Ba₃V₂S₄O₃ was obtained. The crystal structure was confirmed by X‐ray single‐crystal and synchrotron X‐ray powder diffraction (P6₃, a=10.1620(2), c=5.93212(1) Å). X‐ray absorption spectroscopy, in conjunction with multiplet calculations, clearly describes the vanadium in charge‐disproportionated V^IIIS₆ and V^VSO₃ coordinations. The compound is shown to be a strongly correlated Mott insulator, which contradicts previous predictions. Magnetic and specific heat measurements suggest dominant antiferromagnetic spin interactions concomitant with a weak residual ferromagnetic component, and that intrinsic geometric frustration prevents long‐range order from evolving.     

Formation of Diverse Mesophases Templated by a Diprotic Anionic Surfactant

The synthesis system for mesophase formation, using the diprotic anionic surfactant N‐myristoyl‐L ‐glutamic acid (C₁₄GluA) as the structure‐directing agent (SDA) and N‐trimethoxylsilylpropyl‐N,N,N‐trimethylammonium chloride (TMAPS) as the co‐structure‐directing agent (CSDA), has been investigated and a full‐scaled synthesis‐field diagram is presented. In this system we have obtained mesophases including three‐dimensional (3D) micellar cubic Fm m, Pm n, Fd m, micellar tetragonal P4₂/mnm, two‐dimensional (2D) hexagonal p6mm and bicontinuous cubic Pn m, by varying the C₁₄GluA/NaOH/TMAPS composition ratios. From the diagram it can be concluded that the mesophase formation is affected to a high degree by the organic/inorganic‐interface curvature and the mesocage–mesocage electrostatic interaction. Bicontinuous cubic and 2D‐hexagonal phases were found in the low organic/inorganic‐interface curvature zones, whereas micellar cubic and tetragonal mesophases were found in the high organic/inorganic‐interface curvature zones. Formation of cubic Fm m and tetragonal P4₂/mnm was favoured in highly alkaline zones with strong mesocage–mesocage interactions, and formation of cubic Pm n and Fd m was favoured with moderate mesocage–mesocage interactions in the less alkaline zones of the diagram.     

Mesoporous silicas by self-assembly of lipid molecules: ribbon, hollow sphere, and chiral materials

Using lipids (N-acyl amino acids) and 3-aminopropyltriethoxysilane as structure- and co-structure-directing agents, mesoporous silicas with four different morphologies, that is, helical ribbon (HR), hollow sphere, circular disk, and helical hexagonal rod, were synthesized just by changing the synthesis temperature from 0 degrees C to 10, 15, or 20 degrees C. The structures were studied by electron microscopy. It was found that 1) the structures have double-layer disordered mesopores in the HR, radially oriented mesopores in the hollow sphere, and highly ordered straight and chiral 2D-hexagonal mesopores in the disklike structure and helical rod, respectively; 2) these four types of mesoporous silica were transformed from the flat bilayered lipid ribbon with a chain-interdigitated layer phase through a solid-solid transformation for HR formation and a dissolving procedure transformation for the synthesis of the hollow sphere, circular disk, and twisted morphologies; 3) the mesoporous silica helical ribbon was exclusively right-handed and the 2D-hexagonal chiral mesoporous silica was excessively left-handed when the L-form N-acyl amino acid was used as the lipid template; 4) the HR was formed only by the chiral lipid molecules, whereas the 2D-hexagonal chiral mesoporous silicas were formed by chiral, achiral, and racemic lipids. Our findings give important information for the understanding of the formation of chiral materials at the molecular level and will facilitate a more efficient and systematic approach to the generation of rationalized chiral libraries.     

Self-assembly of a cyclic metalladecapyridine from the reaction of 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine with silver(I)

Reaction of Ag( p-MeC 6H 4SO 3) with 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine (PY5) in CH 2Cl 2 gave [Ag (I) 2(PY5) 2](p-MeC 6H 4SO 3) 2 (1). Treatment of 2,6-bis(bis(2-pyridyl)hydroxymethane)pyridine (PY5-OH) with AgNO 3 in MeOH gave [Ag (I) 2(PY5-OH) 2](NO3) 2 (2); in the presence of PPh 3, this reaction afforded [Ag (I)(PY5-OH)(PPh 3)]NO 3 (3). The structures of 1- 3 have been determined by X-ray crystal analysis, revealing four-coordinate Ag (I) ions in these complexes. Both 1 and 2 feature a quadruply branched 28-membered C 16N 10M 2 metallamacrocycle fused to 10 pyridyl groups. On the basis of (1)H NMR measurements, the dinuclear 1 and 2 dissociate into a mononuclear complex upon dissolving in MeCN but in MeOH an equilibrium between the mono- and dinuclear species can be detected.     

Gold(I)-catalyzed intermolecular hydroarylation of alkenes with indoles under thermal and microwave-assisted conditions

An efficient method for intermolecular hydroarylation of aryl and aliphatic alkenes with indoles using a combination of [(PR(3))AuCl]/AgOTf as catalyst under thermal and microwave-assisted conditions has been developed. The gold(I)-catalyzed reactions of indoles with aryl alkenes were achieved in toluene at 85 degrees C over a reaction time of 1-3 h with 2 mol% of [(PR(3))AuCl]/AgOTf as catalyst. This method works for a variety of styrenes bearing electron-deficient, electron-rich, and sterically bulky substituents to give the corresponding products in good to high yields (60-95%). Under microwave irradiation, coupling of unactivated aliphatic alkenes with indoles gave the corresponding adducts in up to 90% yield. Selective hydroarylation of terminal C=C bond of conjugated dienes with indoles gave good product yields (62-81%). On the basis of deuterium-labeling experiments, a reaction mechanism involving nucleophilic attack of Au(I)-coordinated alkenes by indoles is proposed.     

基于磁泳的生物分离分析技术

利用磁场诱导的微粒运动即磁泳对磁响应性粒子进行精细分离,是近年来发展起来的选择性分离细胞和高分子量核酸的有效技术。本文在阐明磁泳分离原理的基础上,介绍了磁泳分离的分流薄层分级技术、四极磁场流动分离技术和微芯片上的自由流磁泳分离技术的装置构造、工作原理及其在生物分离分析中的应用。     

Controlling Metallophilic Interactions in Chiral Gold(I) Double Salts towards Excitation Wavelength‐Tunable Circularly Polarized Luminescence

Materials exhibiting excitation wavelength‐dependent photoluminescence (Ex‐De PL) in the visible region have potential applications in bioimaging, optoelectronics and anti‐counterfeiting. Two multifunctional, chiral [Au(NHC)₂][Au(CN)₂] (NHC=(4R,5R)/(4S,5S)‐1,3‐dimethyl‐4,5‐diphenyl‐4,5‐dihydro‐imidazolin‐2‐ylidene) complex double salts display Ex‐De circularly polarized luminescence (CPL) in doped polymer films and in ground powder. Emission maxima can be dynamically tuned from 440 to 530 nm by changing the excitation wavelength. The continuously tunable photoluminescence is proposed to originate from multiple emissive excited states as a result of the existence of varied Au^I???Au^I distances in ground state. The steric properties of the NHC ligand are crucial to the tuning of Au^I???Au^I distances. An anti‐counterfeiting application using these two salts is demonstrated.     

Iron‐Catalyzed Highly Enantioselective cis‐Dihydroxylation of Trisubstituted Alkenes with Aqueous H2O2

Reliable methods for enantioselective cis‐dihydroxylation of trisubstituted alkenes are scarce. The iron(II) complex cis‐α‐[Fe^II(2‐Me₂‐BQPN)(OTf)₂], which bears a tetradentate N₄ ligand (Me₂‐BQPN=(R,R)‐N,N′‐dimethyl‐N,N′‐bis(2‐methylquinolin‐8‐yl)‐1,2‐diphenylethane‐1,2‐diamine), was prepared and characterized. With this complex as the catalyst, a broad range of trisubstituted electron‐deficient alkenes were efficiently oxidized to chiral cis‐diols in yields of up to 98 % and up to 99.9 % ee when using hydrogen peroxide (H₂O₂) as oxidant under mild conditions. Experimental studies (including ¹⁸O‐labeling, ESI‐MS, NMR, EPR, and UV/Vis analyses) and DFT calculations were performed to gain mechanistic insight, which suggested possible involvement of a chiral cis‐Fe^V(O)₂ reaction intermediate as an active oxidant. This cis‐[Fe^II(chiral N₄ ligand)]²⁺/H₂O₂ method could be a viable green alternative/complement to the existing OsO₄‐based methods for asymmetric alkene dihydroxylation reactions.