Direct CH Amidation of Benzoic Acids to Introduce meta‐ and para‐Amino Groups by Tandem Decarboxylation

The Ir‐catalyzed mild C?H amidation of benzoic acids with sulfonyl azides was developed to give reactions with high efficiency and functional‐group compatibility. Subsequent protodecarboxylation of ortho‐amidated benzoic acid products afforded meta‐ or para‐substituted (N‐sulfonyl)aniline derivatives, the latter being inaccessible by other C?H functionalization approaches. The decarboxylation step was compatible with the amidation conditions, enabling a convenient one‐pot, two‐step process.     

Iodine(III)‐Mediated para‐Selective Direct Imidation of Anilides

The direct, nucleophilic imidation of acetanilide derivatives has been performed under mild, iodine(III)‐mediated or ‐catalyzed conditions, employing lithium triflimide as the nitrogen source. The reaction exhibits exclusive regioselectivity for the para position and shows a good tolerance for varied functional groups at both the ortho or meta positions. Preliminary mechanistic data suggest that the LiNTf₂ reagent plays a key role in the reactivity.     

A Nanoparticle Catalyst for Heterogeneous Phase Para‐Hydrogen‐Induced Polarization in Water

Para‐hydrogen‐induced polarization (PHIP) is a technique capable of producing spin polarization at a magnitude far greater than state‐of‐the‐art magnets. A significant application of PHIP is to generate contrast agents for biomedical imaging. Clinically viable and effective contrast agents not only require high levels of polarization but heterogeneous catalysts that can be used in water to eliminate the toxicity impact. Herein, we demonstrate the use of Pt nanoparticles capped with glutathione to induce heterogeneous PHIP in water. The ligand‐inhibited surface diffusion on the nanoparticles resulted in a ¹H polarization of P=0.25 % for hydroxyethyl propionate, a known contrast agent for magnetic resonance angiography. Transferring the ¹H polarization to a ¹³C nucleus using a para‐hydrogen polarizer yielded a polarization of 0.013 %. The nuclear‐spin polarizations achieved in these experiments are the first reported to date involving heterogeneous reactions in water.     

Monomers that form conducting polymers as structure-directing agents: synthesis of microporous molecular sieves encapsulating poly-para-phenylenevinylene

We have developed a novel concept that uses monomers required for making conducting polymers as organic structure-directing agents, for the synthesis of microporous molecular sieves. We show that these monomers facilitate the formation of crystalline and amorphous molecular sieves depending on the synthesis procedure. The monomers filling the pores of the silicates can be polymerized under certain conditions, resulting in a polymer immobilized and protected inside the matrix. The concept was exemplified with para-phenylenemethylene-bis(1-tetrahydrothiophenium) and para-phenylenemethylene-bis(trimethylammonium) that were used to template microporous molecular sieves and subsequently to obtain poly-para-phenylenevinylene (PPV) inside the matrix. The organic self-assembled organic-inorganic material was extensively characterized and the implication on electrical conductivity is presented.     

Physisorption and ortho–para conversion of molecular hydrogen on solid surfaces

Molecular hydrogen exists in nuclear-spin isomers of ortho and para species according to the total nuclear spin. These species are correlated to the rotational states with even and odd rotational quantum numbers because of the symmetry of the total wavefunction with respect to the permutation of the two nuclei. Although interconversion between the ortho and para states is extremely slow in an isolated state, the conversion is promoted in a physisorption state via interaction with surfaces of not only magnetic but also diamagnetic materials. In a physisorption state, the rotational motion of hydrogen molecules is modified due to the potential anisotropy. The physisorption properties and interconversion rate of the ortho and para hydrogen have recently been investigated on well-defined surfaces, which allow detailed comparison with theory. Furthermore, relative abundance of the ortho and para hydrogen in astronomical circumstances has been reported in recent years, which often shows a value out of equilibrium with the environment temperature. Physisorption and ortho–para conversion on the surfaces of interstellar media are expected to enable deeper understanding of astronomical phenomena. In this article, we review recent progress of experimental and theoretical studies on the physisorption and ortho–para conversion of molecular hydrogen and its relevance to the recent astronomical observation.     

Interrupted super framework of the crystal structure of Cs[Be2(PO4)(PO4H)] cesium diberyllium phosphate hydrophosphate

The crystal structure of cesium diberyllium phosphate hydrophosphate Cs[Be₂(PO₄)(PO₄H)] obtained hydrothermally is analyzed. Unit cell parameters are: a = 4.8860(5) ?, b = 10.7330(11) ?, c = 13.0061(15) ?, α = 92.540(10)°, β = 92.451(9)°, γ = 90.948(9)°, space group P . In the structural motif consisting of PO₄ and BeO₄ tetrahedra, Be,P two-link chains and ribbons are distinguished, typical of a short a-translation of ≈4.9 ?. The presence of ternary and terminal O ligands along with bridging ones determines the term interrupted super framework. The group of two Be tetrahedra with a common edge is detected for beryllium phosphates for the first time. Original Russian Text Copyright ? 2009 by V. V. Bakakin, Yu. V. Seretkin, and S. P. Demin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 369–373, March–April, 2009.     

Spectroscopic Study of the Photophysical Properties of Rare Earth Ions Encapsulated: Water Soluble Functional Calixresorcin[4]Arene

Abstract

A novel macrocyclic compound-water soluble functional calixresorcin[4]arenes—tetra para sulfo-phenylmethyl-calixresorcin[4]arenes was synthesized for the first time. the photophysical properties of terbium and europium ions encapsulated in the macrocyclic ligand were studied in detail. the triplet state energy of the calixresorcin[4]arene was determined to be 24400 cm^?1 by the low temperature phosphorescence spectrum and it was found that it can sensitize both terbium ion and europium ion. the possible energy transfer process between the functional calixresorcin[4]arene and the encapsulated Tb³⁺ and Eu³⁺ was discussed. the luminescence quantum efficiency of Tb³⁺- calixresorcin[4]arene was calculated.     

Oxygen-17 NMR Spectroscopy: Effect of Substituents on Chemical Shifts and Width Line in Ortho Substituted Nitro Benzenes

¹⁷O-NMR spectra, of ortho, meta and para substituted nitrobenzene are reported. The ¹⁷O nucleus of NO₂ group in ortho derivatives absorb at lower field that meta and para compounds. Moreover, width line of ¹⁷O resonance appears to be strongly dependent by substituent position. The ¹⁷O chemical shifts are correlated with U. V. spectra and X-ray diffraction data.     

Addition curing thermosets endcapped with 4-amino [2.2] paracyclophane

A new family of addition curing polyimides were prepared that contained 4-amino [2.2]-paracyclophane as the endcap. An improved synthesis of the endcap 4-amino-[2.2] cyclophane was accomplished increasing the yield to 60% and simplifying the procedure. DSC and rheological analysis of endcapped polyimide oligomers confirmed that the onset for polymerization of the ethylene bridge was 250°C. ¹³C CP/MAS NMR was used to determine the structural changes of the oligomers after thermal treatment. The cyclophane capped polyimides were successfully compression molded to from void free neat resin specimens. T'_gs as high as 353°C were obtained by thermomechanical analysis for postcured samples. Preliminary thermal stability studies (TGA) suggest that these resins have a high onset of decomposition ranging from 549 to 567°C.     

凝胶净化-高效液相色谱法检测对位红在辣椒酱和辣酱油中的残留量

运用高效液相色谱(HPLC)法分析并采用凝胶净化系统(GPC)预处理,建立了测定辣椒酱、辣酱油等复杂样品中对位红残留量的检测方法。辣椒酱、辣酱油样品用乙腈提取,经过净化、浓缩,用乙腈定容进行检测。色谱柱为资生堂MG-ⅡC18柱,直接采用等度洗脱,流动相为乙腈-水;采用可变波长检测器(VWD),检测波长为485 nm。对位红标准溶液在0.02~1.0 mg/L浓度范围内,药物峰面积与浓度呈良好的线性关系,其相关系数的平方(R2)为0.9978。辣椒酱、辣酱油样品中添加药物回收率分别为:71.0%±2.5%~90.4%±4.0%和72.1%±3.1%~91.8%±2.0%;对位红在复杂样品中的残留量检测的定量限为0.05μg/g。