Guest-induced assembly of tetracarboxyl-cavitand and tetra(3-pyridyl)-cavitand into a heterodimeric capsule via hydrogen bonds and CH-halogen and/or CH-pi interaction: control of the orientation of the encapsulated guest

The guest- or solvent-induced assembly of a tetracarboxyl-cavitand 1 and a tetra(3-pyridyl)-cavitand 2 into a heterodimeric capsule 1.2 in a rim-to-rim fashion via four intermolecular CO(2)H.N hydrogen bonds has been investigated both in solution and in the solid state. In the (1)H NMR study, a 1:1 mixture of1a and 2a (R = (CH(2))(6)CH(3)) in CDCl(3) gave a mixture of various complicated aggregates, whereas this mixture in CDCl(2)CDCl(2) or p-xylene-d(10) exclusively produced the heterodimeric capsule 1a.2a. It was found that an appropriate 1,4-disubstituted-benzene is a suitable guest for inducing the exclusive formation of 1a.2a in CDCl(3). The ability of a guest to induce the formation of guest-encapsulating heterodimeric capsule, guest@(1a.2a), increased in the order p-ethyltoluene < 1-ethyl-4-methoxybenzene < or = 1-ethyl-4-iodobenzene < or = 1,4-dibromobenzene < 1-iodo-4-methoxybenzene < or= 1,4-dimethoxybenzene < or = 1,4-diiodobenzene. The (1)H NMR study revealed that a CH-halogen interaction between the inner protons of the methylene-bridge rims (-O-H(out)CH(in)-O-) of the 1a and 2a units and the halogen atoms of 1,4-dihalobenzenes and a CH-pi interaction between the methoxy protons of 1,4-dimethoxybenzene and the aromatic cavities of the 1a and 2a units play important roles in the formation of 1,4-dihalobenzene@(1a.2a) and 1,4-dimethoxybenzene@(1a.2a), respectively. A preliminary single-crystal X-ray diffraction analysis of guest@(1b.2b) (R = (CH(2))(2)Ph; guest = 1-iodo-4-methoxybenzene or p-xylene) confirmed that the guest encapsulated in 1b.2b is oriented with the long axis of the guest along the long axis of 1b.2b and that the iodo and the methoxy groups of the encapsulated 1-iodo-4-methoxybenzene are specifically oriented with respect to the cavities of the 2b and 1b units, respectively.     

A GaCl3-catalyzed [4+1] cycloaddition of alpha,beta-unsaturated carbonyl compounds and isocyanides leading to unsaturated gamma-lactone derivatives

A GaCl3-catalyzed reaction of alpha,beta-unsaturated ketones with isocyanides leading to the formation of unsaturated lactone derivatives is described. This is the first example of the catalytic [4+1] cycloaddition of alpha,beta-unsaturated ketones and isocyanides. GaCl3 is an excellent catalyst due to its lower oxophilicity, which is desirable for all of the key steps, such as E/Z isomerization, cyclization, and deattachment from the products.     

A novel method for determination of inorganic oxyanions by electrospray ionization mass spectrometry using dehydration reactions

Novel methods for the determination of inorganic oxyanions by electrospray (ES) ionization mass spectrometry have been developed using dehydration reactions between oxyanions and carboxylic acids at the ES interface. Twelve oxyanions (VO₃^?, CrO₄^2?, MoO₄^2?, WO₄^2?, BO₃^3?, SiO₃^2?, SiO₄^4?, AsO₄^4?, AsO₂^?, SeO₄^2?, SeO₃^2? and NO₂^?), out of 16 tested, reacted with at least one of four aminopolycarboxylic acids, i.e. iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), trans‐1,2‐diaminocyclohexane‐N,N,N′,N′‐tetraacetic acid and triethylenetetramine‐N,N,N′,N″,N′″,N′″‐hexaacetic acid, at the ES interface to produce the dehydration products that gave intense mass ion responses, sufficient for trace analysis. As examples, trace determinations of Cr^VI and silica in water samples were achieved after online ion exchange chromatography, where the dehydration product of CrO₄^2? and NTA (m/z 290) and that of SiO₄^4? and IDA (m/z 192) were measured. The limits of detection of the respective methods were 17 nM (0.83 ng Cr/ml) for Cr^VI and 0.17 μM (4.8 ng Si/mL) for SiO₄^4?. Copyright © 2016 John Wiley & Sons, Ltd.     

Distorted Porphyrins with High Stability: Synthesis and Characteristic Electronic Properties of Mono- and Di-Nuclear Tricarbonyl Rhenium Tetraazaporphyrin Complexes

Mono- and di-nuclear tricarbonyl Re(I) tetraazaporphyrin complexes ( Re₁TAP and Re₂TAP ) are investigated and compared with Re(I) phthalocyanine complexes ( Re₁Pc and Re₂Pc ). Although Re₂Pc is unstable in polar solvents, and easily undergoes demetallation reaction, the coordination of the TAP ligand significantly improves the tolerance toward polar solvents, affording more stability to Re₂TAP . Additionally, the incorporation of [Re(CO)₃]⁺ unit(s) and the TAP ligand results in remarkable positive shifts in both oxidation and reduction potentials. Consequently, the more positive oxidation potentials of the ReTAP complexes significantly increase the tolerance toward oxidation, while the reduction potential indicates that Re₂TAP is suitable for a soluble electron acceptor. In contrast to Re₁Pc and Re₂Pc , Re₁TAP and Re₂TAP show unique broad Q bands, which can be attributed to the admixture of the π-π* and metal-to-ligand charge transfer characters, owing to the lowered π orbital energy in the TAP complexes. This study is useful for controlling electronic properties and realizing high stability in Pc analogues.     

Physical and Chemical Properties of Four-Membered Bis(triphenylphosphane)platinum(II) Sulfenato Thiolato Complexes

The reaction of isolable dithiirane 1-oxides with (Ph 3 P) 2 Pt( m 2 -C 2 H 4 ) provided the title complexes in high yields. 31 P NMR spectroscopy of the phosphine ligands of the complexes and x-ray crystallographic analysis of a complex were reported.     

Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by [PMO12O40]3-[C5H5N+(CH2)15CH3]3

Applicatims a Mo- and W-based heteropoly acids (HPA) as a catalyst in the oxidation of olefins have extensively been investigated¹. However, a patent work is only attempted concerning the evoxidatim of olefins with H₂0₂ by HPA²⁾ since the oxirane ring is cleaved because of a strong acidity of HPA itself. Herein, an effective epoxidatim of some allylic alcohols with H₂0₂ by a new Mo-species (MPCP), which was prepared from 12-molybdatophosphoric acid (H₃PMo₁₂0₄₀) and cetylpyridinium chloride (C₅H₅N (CH₂), ₁₅CH₃- C1^-) under two-phase conditions using chloroform as an organic solvent, is described.