Organosilicate-surfactant lamellar mesophase with molecular-scale periodicity in the silicate layers

The synthesis of lamellar mesophases of organosilicate-surfactant composites with periodicity within the silicate layers due to periodic arrangement of phenylene- and biphenylylene-silica moieties is reported.     

Estimation of the probabilities of misclassification for a linear discriminant function in the univariate normal case

Summary The probability of misclassification inherent in the use of a linear discriminant function is not necessarily known to the experimenter using such a function. Various estimators calculated from the sample used to generate the sample discriminant function have been proposed. The purpose of this paper is to evaluate and to compare several of these estimators by using unconditional mean square error as the criterion. Discussion is restricted to the case where each of the distributions is univariate normal with common variance. This paper is partially based on the Ph.D. thesis of N. Sedransk [7] at Iowa State University.     

One-electron oxidation of anispinacolone with diaroyl peroxides: Mechanistic changeover of the peroxide function from radical to molecular oxidation

Oxidative cleavage of anispinacolone (An₃C·CO·An, An=p-methoxyphenyl) with diaroyl peroxides proceeds by electron-transfer mechanism, which starts with rate-determining decomposition of the peroxide, unimolecular for dibenzoyl and bimolecular for bis(3,5-dinitrobenzoyl) peroxide.     

Asymmetric Synthesis of 2H‐Azirines with a Tetrasubstituted Stereocenter by Enantioselective Ring Contraction of Isoxazoles

Highly strained 2H‐azirines with a tetrasubstituted stereocenter were synthesized by the enantioselective isomerization of isoxazoles with a chiral diene–rhodium catalyst system. The effect of ligands and the coordination behavior support the proposed catalytic cycle in which the coordination site is fixed in favor of efficient enantiodiscrimination by a bulky substituent of the ligand. In silico studies also support the existence of a rhodium–imido complex as a key intermediate for enantiodiscrimination.     

Excited-state intramolecular proton transfer (ESIPT) fluorescence from 3-amidophthalimides displaying RGBY emission in the solid state

Fluorescence properties of phthalimide derivatives (1) incorporating sulfonamide and acetamide functionalities at the 3-position were investigated both in solution and in the solid states to reveal the effects of the amide functionalities on the fluorescence properties. In the solid state, sulfonamides 1a and 1b, respectively, gave off red (λ^F_max 595?nm) and green (λ^F_max 537?nm) emission through an ESIPT process. Acetamides 1c and 1d, respectively displayed blue (λ^F_max 432?nm) and yellow (λ^F_max 560?nm) emission. Through simply modifying the amide functionality, phthalimide 1 displayed multicolor RGBY emission in the solid state.     

Synthesis and conformational analysis of N-aryl-N-(3-thienyl)acetamides

The cis-trans conformational equilibrium of amides is of interest because it can be used to control functional activity. Here, we designed and synthesized a series of N-(3-thienyl)amides in order to study the factors affecting their conformational equilibrium. NMR studies showed that the major conformer of N-methyl-N-(3-thienyl)amide in solution is the E-form (cis form), as is the case for N-methylacetamide. For N-aryl-N-(3-thienyl)amides bearing an N-phenyl moiety, the major conformers differ depending on not only the relative π-electron density of the N-aryl moiety, but also its size. X-ray analysis showed that their solid-state conformational preferences were similar to those in solution.