Straightforward Synthesis of 1,2-Amino Phosphate Diesters and Application to the Synthesis of Novel 1,2-Amino Ether Diesters

A variety of 1,2-amino alcohol diesters 1 reacted smoothly with diethyl chlorophosphate under basic conditions to afford the corresponding 1,2-amino phosphate diesters 2 in excellent yields. These compounds served as useful precursors for subsequent nucleophilic attack by alcohols in an S_N2 fashion to provide 1,2-amino ether diesters 3.     

Homogenization of periodic bi-isotropic composite materials

In this paper, we present a new method for homogenizing the bi-periodic materials with bi-isotropic components phases. The presented method is a numerical method based on the finite element method to compute the local electromagnetic properties. The homogenized constitutive parameters are expressed as a function of the macroscopic electromagnetic properties which are obtained from the local properties. The obtained results are compared to Unfolding Finite Element Method and Maxwell–Garnett formulas.     

Electromagnetic interactions at RHIC and LHC

At LHC energies, the Lorentz factor will be 3400 for Pb+Pb collisions, and the electromagnetic interactions will play important roles. The cross sections for the electromagnetic particle productions are very large and cannot be ignored for the lifetimes of the beams and background. In this article, we are going to study some of the electromagnetic processes at the RHIC and the LHC and show the cross section calculations of the electron-positron pair production with the giant dipole resonance of the ions.     

Facile synthesis of Cu-LDH with different Cu/Al molar ratios: application as antibacterial inhibitors

Research on Chemical Intermediates - A range of Cu-LDHs has been synthesized by co-precipitation using metal nitrate precursors and sodium carbonate under varying molar ratios Cu/Al...     

Practical Preparation of β‐Amino‐α‐Hydroxy Diesters: Key Intermediates for 1,4‐Oxazin‐2‐Ones

In the presence of a catalytic amount of amino acid hydrochloride, trans‐β‐phenylglycidic ester undergoes ring opening with high stereo‐ and regioselectivity when treated with glycine esters. Alkylation of the resulting β‐amino‐α‐hydroxy diesters with benzyl bromide, followed by cyclization to furnish the expected 1,4‐oxazin‐2‐ones, is also described.     

Dihydrooxazolones and dihydroimidazolones derived from acylglycines: syntheses,molecular structures and supramolecular assembly

Syntheses and structures are described for some alkylidene‐substituted dihydrooxazolones and dihydroimidazoles derived from simple acylglycines. A second, triclinic, polymorph of 4‐benzylidene‐2‐(4‐methylphenyl)‐1,3‐oxazol‐5(4H)‐one, C₁₇H₁₃NO₂, (I), has been identified and the structure of 2‐methyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one, C₉H₇NO₂S, (II), has been rerefined taking into account the orientational disorder of the thienyl group in each of the two independent molecules. The reactions of phenylhydrazine with 2‐phenyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one or 2‐(4‐methylphenyl)‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one yield, respectively, 3‐anilino‐2‐phenyl‐5‐[(thiophen‐2‐yl)methylidene]‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₁₀H₁₅N₃OS, (III), and 3‐anilino‐2‐(4‐methylphenyl)‐5‐[(thiophen‐2‐yl)methylidene]‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₂₁H₁₇N₃OS, (IV), which both exhibit orientational disorder in their thienyl groups. The reactions of 2‐phenyl‐4‐[(thiophen‐2‐yl)methylidene]‐1,3‐oxazol‐5(4H)‐one with hydrazine hydrate or with water yield, respectively, N‐[3‐hydrazinyl‐3‐oxo‐1‐(thiophen‐2‐yl)prop‐1‐en‐2‐yl]benzamide and 2‐(benzoylamino)‐3‐(thiophen‐2‐yl)prop‐2‐enoic acid, which in turn react, respectively, with thiophene‐2‐carbaldehyde to form 2‐phenyl‐5‐[(thiophen‐2‐yl)methylidene]‐3‐{[(E)‐(thiophen‐2‐yl)methylidene]amino}‐3,5‐dihydro‐4H‐imidazol‐4‐one, C₁₉H₁₃N₃OS₂, (V), which exhibits orientational disorder in only one of its thienyl groups, and with methanol to give methyl (2Z)‐2‐(benzoylamino)‐3‐(thiophen‐2‐yl)prop‐2‐enoate, C₁₅H₁₃NO₃S, (VI). There are no direction‐specific intermolecular interactions in the crystal structure of the triclinic polymorph of (I), but the molecules of (II) are linked by two independent C—H...O hydrogen bonds to form C₂²(14) chains. Compounds (III) and (IV) both form centrosymmetric R₂²(10) dimers built from N—H...O hydrogen bonds, while compound (V) forms a centrosymmetric R₂²(10) dimer built from C—H...O hydrogen bonds. In the structure of compound (VI), a combination of N—H...O and C—H...π(arene) hydrogen bonds links the molecules into sheets. Comparisons are made with some similar compounds.     

Remote control of extended depth of field focusing

We propose a novel system allowing remote control of the location of the extended focal depth region. This system may find applications in situations where controllable optical access to an enclosure is needed and it is desirable to minimize the movement of the focusing lens. Our scheme uses three axicons, two external ones generating a ring and an internal one producing the focal region. We present a proof of concept of this system, consisting of measurements of the longitudinal and transverse intensity distributions, for a reference configuration and one with a displaced position of the extended depth of field focus.     

Polarized Infrared Spectra of the H(D) Bond in 2‐Thiophenic Acid Crystals: A Spectroscopic and Computational Study

Polarized IR spectra of the hydrogen bond in 2‐thiophenic acid crystals, isotopically neat and of mixed H/D isotopic content, are measured at 298 and 77 K in the “residual” νO? H and νO? D band frequency ranges. This crystalline system provides spectra in these band frequency ranges that differ considerably in intensity distribution from the spectra of other H‐bonded centrosymmetric dimeric species. This change in the spectral properties of the crystals is probably due to the influence of the sulfur atoms from the thiophene aromatic rings, which are directly linked to the (COOH)2 or (COOD)2 cycles. The magnitude of this effect correlates with the net electronic charge distribution at the 2‐ and 3‐positions of substituted thiophene rings, which in a different way influences the electron charge density in the hydrogen bonds of the two thiophenic acid isomers. The experimental results for spectral structures are compared to predictions obtained with theoretical calculations involving the combined effects of anharmonicities, Davydov coupling, Fermi resonances, and direct and indirect relaxations within the framework of the linear response theory. Numerical results show that mixing of all these effects allows satisfactory reproduction of the main features of the experimental IR line shapes of crystalline H‐ and D‐bonded 2‐thiophenic acid at room and liquid‐nitrogen temperatures.