Mesoporous Molecular Sieve MCM‐41 as a Novel and Efficient Catalyst to Synthesis of 2‐Substituted Benzimidazoles

o‐Phenylenediamine derivatives readily react with benzoyl chloride derivatives in the presence of MCM‐41 as catalyst to yield 2‐substituted benzimidazoles in very good yields.     

Fe(HSO4)3: An efficient, heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyi-14H-dibenzo[a.j]xanthenes

Fe(HSO4)3 has been used as an efficient and reeyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.     

Synthesis and Crystal Structure of CeIII and BiIII Complexes and Solution Studies of ZnII,CdII, PbII,CeIII, and BiIII Complexes Obtained from Proton Transfer Compounds Containing 2,6‐Pyridinedicarboxylate Ion

The two complexes (pydaH)₂[Ce(pydc)₂(H₂O)₂]₂ · 2H₂O (1) and (phenH)₂[Bi(pydc)₂(H₂O)]₂ · 5H₂O (2) were prepared from the proton transfer compounds containing the 2,6‐pyridinedicarboxylate ion. 1 was synthesized from the reaction of Ce(NO)₃ · 6H₂O with the proton transfer compound, (pydaH₂)(pydc), (pyda=2,6‐diaminopyridine, pydcH₂=2,6‐pyridinedicarboxylic acid). 2 was synthesized from the reaction of proton transfer compound, (phenH)₂(pydc), (phen=1,10‐phenanthroline), with Bi(NO₃)₃ · 5H₂O. The characterization was carried out using IR, ¹H and ¹³C NMR spectroscopy, elemental analysis and single crystal X‐ray diffraction. The complex 1 crystallizes in the space group of the triclinic system, and contains two molecules per unit cell. The structure has been refined to a final value for the crystallographic R factor of 0.0342 based on 8851 reflections. The unit cell parameters are: a = 9.753(2) Å, b = 10.503(2) Å, c = 10.774(2) Å, α = 83.905(4)°, β = 88.089(4)°, and γ = 82.636(3)°. The crystal structure illustrates that cerium atoms are connected together through the four‐membered ring Ce₂O₂. 2,6‐Pyridinedicarboxylate fragment acts as a tridentate ligand. The molecular structure contains four (pydc)^2? ligands, two of which are bridge ligands linking the two central atoms. The complex 2 crystallizes in the space group of the triclinic system and contains two molecules per unit cell. The unit cell dimensions are: a = 8.8860(4) Å, b = 12.0132(6) Å, c = 13.0766(6) Å, α = 100.967(1)°, β = 96.681(1)° and γ = 94.191(1)°. The structure has been refined to a final value for the crystallographic R factor of 0.0471 based on 9576 reflections. In this complex, 2,6‐pyridinedicarboxylate moiety has acted as a tridentate ligand and the lattice is composed of binuclear unit, [Bi(pydc)₂(H₂O)]₂^2?, (phenH)⁺ counter ions and five lattice waters. In both complexes hydrogen bonds, π‐π stacking and ion‐pairing play important roles in stabilizing the corresponding lattice. The stoichiometry and stability of the Zn^II, Cd^II, Pb^II, and Ce^III complexes with (pydaH₂)(pydc) in aqueous solution were investigated by potentiometric pH titration. The solution studies revealed that the stoichiometry of the crystalline complexes of the proton transfer system (pydaH₂)(pydc) with Ce^III, obtained in this study, and those with Zn^II, Cd^II and Pb^II, reported in our previous studies, are in close agreements. The complexation reactions of phen, pydc, and 2phen+pydc with Bi^III in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described.     

Observation of Kerr nonlinearity in microcavities at room temperature

We have devised and experimentally verified a method for observation of the optical Kerr effect in microcavities at room temperature. The technique discriminates against the much larger and typically dominant thermal component of nonlinearity by using its relatively slow frequency response. Measurement of the Kerr coefficient or equivalently of the third-order nonlinear susceptibility of the cavity material is demonstrated for a silica microcavity. With this approach, useful information about the characteristic thermal response time in microresonators can also be acquired.     

Multi-component synthesis of spiro[diindeno[1,2-b:2′,1′-e]pyridine-11,3′-indoline]-triones using zinc terephthalate metal-organic frameworks

The present article describes an efficient one-pot method for the preparation of spiro[diindeno[1,2-b:2′,1′-e]pyridine-11,3′-indoline]-trione derivatives from a three-component condensation reaction of 1,3-indandione, aromatic amines and isatins in the presence of a zinc terephthalate metal-organic framework Zn (BDC) MOF as the catalyst under solvent-free conditions. High yields, short reaction times, simple workup and environmentally benign procedure are advantages of this protocol. The Zn (BDC) MOF catalyst can be recovered and reused several times without loss of activity. The catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infra red, X-ray powder diffraction and thermal gravimetric analysis.     

Rapid microwave promoted heterocyclization of primary amines with triethyl orthoformate and sodium azide using zinc sulfide nanoparticles as recyclable catalyst

Microwave assisted synthesis of 1-substituted-1H-tetrazoles was developed using zinc sulfide nanoparticles as heterogeneous catalyst under solvent free conditions. The tetrazole derivatives were easily prepared through hterocyclization of primary amines with triethyl orthoformate and sodium azide in the presence of ZnS NPs. The experimental results were shown that a series of 1-substituted tetrazoles were synthesized under microwave irradiation by ZnS NPs as an effective and reusable heterogeneous catalyst in excellent yields. This protocol has advantages rather than other reported methods such as non-acidic catalyst, solvent free conditions and greener process as well as a solid recyclable catalyst. The catalyst was recovered and reused for several cycles with consistent activity.     

Preparation and characterization of SbCl<Subscript>5</Subscript> supported on coconut shell as nanocatalyst for the synthesis of novel 2-amino-3-phenylsulfonyl-4-aryl-4<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">h</Emphasis>]chromens

Pentachlorid antimony supported on coconut shell as an efficient and novel catalyst for one-pot synthesis of 2-amino-3-phenylsulfonyl-4-aryl-4H-benzo[h]chromen through three-component condensation of \( \alpha \)- naphtol, arylaldehydes and phenylsulfonyl (acetonitrile). Nanocatalyst pentachloride antimony supported on coconut shell was manufactured and characterized by FT-IR, TGA/DTG, XRD, EDX, FESEM and TEM techniques. The present method has advantages such as high activity, high reaction rate, recoverability of nanocatalyst, a simple experimental procedure, without any using of hazardous organic solvents under green conditions.     

Nanoscale Optoregulation of Neural Stem Cell Differentiation by Intracellular Alteration of Redox Balance

Regulation of stem cell (SC) fate, a decision between self‐renewal and differentiation, is of immense importance in regenerative medicine and has been proven to be a powerful stimulus regulating many cell functions influencing the SC fate. This study uses triphenylphosphonium‐functionalized gold nanoparticles (TPP‐AuNPs) to explore the interplay of intracellular electromagnetic (EM) exposure and the SC fate. Localized EM waves are generated inside neural stem cells (NSCs) to stimulate TPP‐AuNPs (AuNPs), targeting the mitochondria through inducing reactive oxygen species and differentiating these cells into neurons. Following laser irradiation of TPP‐AuNPs‐transfected NSCs, their differentiation to neurons is monitored by tracing the relevant markers both at the genetic and protein levels. The electrophysiology technique is further used to examine the functionality of neurons. The results confirm that TPP‐AuNPs subjected to electromotive forces have the potential to regulate cellular fate, although further investigations are still required to shed light on the mechanisms underlying the interaction of EM‐stimulated TPP‐AuNPs on cellular fate to design highly adjustable cell differentiation and reprogramming methods.     

Atomic Layer Deposited Non‐Noble Metal Oxide Catalyst for Sodium–Air Batteries: Tuning the Morphologies and Compositions of Discharge Product

Catalysts can play a critical role in the development of sodium–air batteries (SABs). Atomic layer deposition (ALD) technology enables rational design and atomic utilization of catalyst by homogenously distributing catalytically active material on a variety of substrates. Here, a novel hierarchical nanostructured Co₃O₄ is decorated on carbon nanotubes by ALD (CNT@Co₃O₄) and used as a catalyst for SABs. CNT@Co₃O₄ demonstrates better performance and longer cycle life than a mechanically mixed CNT/Co₃O₄ nanocomposite. Well‐dispersed ALD Co₃O₄ catalyst on CNTs, which serves as functionalized active sites, enables rapid electron exchange and high oxygen reduction/evolution activities. Synchrotron‐based X‐ray analysis including X‐ray absorption near edge structure, extended X‐ray absorption fine structure, and scanning transmission X‐ray microscopy characterization techniques have been employed to elucidate the activity of Co₃O₄ and to investigate the nanoscale discharge product distribution found in SABs. This analysis reveals that Co₃O₄ catalyst can promote the electrochemical decomposition of sodium peroxide, superoxide, and carbonates. The role of the catalyst in SABs is clarified and discussed in detail.     

Modified Graphite Paste Electrode with Lewatit FO36 Nanoresin/Multi-Walled Carbon Nanotubes for Determination of Quercetin

In the present study, the electrochemical oxidation of quercetin (QUR) was investigated using a graphite paste electrode (GPE) modified with multi-walled carbon nanotube and Lewatit FO36 nanoresin (LFONR-MWCNT/GPE). LFONR-MWCNT/GPE could effectively a sensitive anodic peak at around 0.23 V (vs. SCE) in a 0.10 M phosphate buffer solution. Modified electrode revealed that activated with multiwalled carbon nanotube and LFONR was capable of facilitating electron transfer and increasing surface area. The electrochemical oxidation of QUR was studied using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Some kinetic parameters for electrochemical oxidation of QUR including total number of electrons (n) and standard heterogeneous rate constant (k_s) were also determined. The calibration graph consisted of two linear segments of 1.8–25.0 μM, and 25.0–570.0 μM with a detection limit of 0.213 μM (based on 3S_b). The applicability of the method to juice of peach, red grape, sour cherry and Gincora tablets analysis was also evaluated.