A mild and efficient approach for the selective deprotection of benzyl and phenyl trimethylsilyl ethers in 1-butyl-3-methyl-imidazolium chloride

1-Butyl-3-methyl-imidazolium chloride ([bmim]Cl) in the absence of any catalyst mediated the selective deprotection of benzyl and phenyl trimethylsilyl (TMS) ethers to the corresponding alcohols and phenol in good yields at room temperature even in presence of alkyl silyl ethers. The work-up of reactions is very simple and the products do not require further purification. The ionic liquid (IL) can be recycled and reused for several runs without any significant loss of activity.     

Efficient,Convenient and Mild Three‐Component Template Preparation and Characterization of Some New Schiff Base Complexes

A few kinds of novel Schiff base complexes have been prepared by three‐component reaction of the substituted hydroxyacetophenone with several aliphatic diamines and transition metals such as; Cu(II), Co(II), Mn(II), Zn(II) and UO₂(II) under mild reaction conditions. The products have been afforded with excellent yields and appropriate reaction times. The structures of these ligands have been characterized by their IR, ¹H NMR, ¹³C NMR and MS spectral and physical data.     

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.     

Lifshitz interaction between dielectric bodies of arbitrary geometry

A formulation is developed for the calculation of the electromagnetic-fluctuation forces for dielectric objects of arbitrary geometry at small separations, as a perturbative expansion in the dielectric contrast. The resulting Lifshitz energy automatically takes on the form of a series expansion of the different many-body contributions. The formulation has the advantage that the divergent contributions can be readily determined and subtracted off, and thus makes a convenient scheme for realistic numerical calculations, which could be useful in designing nanoscale mechanical devices.     

Propulsion of a molecular machine by asymmetric distribution of reaction products

A simple model for the reaction-driven propulsion of a small device is proposed as a model for (part of) a molecular machine in aqueous media. The motion of the device is driven by an asymmetric distribution of reaction products. The propulsive velocity of the device is calculated as well as the scale of the velocity fluctuations. The effects of hydrodynamic flow as well as a number of different scenarios for the kinetics of the reaction are addressed.     

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.