Complexation of the adjacent actinide ions americium(III) and curium(III) by the ligand N,N'-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2bp18c6) in aqueous solution was studied to quantify and characterize its americium/curium selectivity. Liquid-liquid extraction and spectrophotometric titration indicated the presence of both fully deprotonated and monoprotonated complexes, An(bp18c6)(+) and An(Hbp18c6)(2+) (An = Am or Cm), at the acidities that would be encountered when treating nuclear wastes. The stability constants of the complexes in 1 M NaNO3 determined using competitive complexation were log β101 = 15.49 ± 0.06 for Am and 14.88 ± 0.03 for Cm, indicating a reversal of the usual order of complex stability, where ligands bind the smaller Cm(III) ion more tightly than Am(III). The Am/Cm selectivity of bp18c6(2-) that is defined by the ratio of the Am and Cm stability constants (β101 Am/β101 Cm = 4.1) is the largest reported so far for binary An(III)-ligand complexes. Theoretical density functional theory calculations using the B3LYP functional suggest that the ligand's size-selectivity for larger 4f- and 5f-element cations arises from steric constraints in the crown ether ring. Enhanced 5f character in molecular orbitals involving actinide-nitrogen interactions is predicted to favor actinide(III) complexation by bp18c6(2-) over the complexation of similarly sized lanthanide(III) cations.

The first-order phase transitions in adsorbed monolayers of 2-hydroxyethyl laurate have been studied by film balance and Brewster angle microscopy (BAM). A cusp point in the surface pressure-time (π-t) curves indicates the commencemnet of phase transition. The critical surface pressure necessary for the phase transition increases with increasing temperature. Large size circular domains having characterishtic internal stripes are observed up to 10 °C. The width of the stripes increases with increasing termperature. The separate stripes in a domain undergo continuous narrowing into a core defect which lies on the domain peripheral line at 2 °C. The core defect seems to be also present at higher temperatures but remains far out of the doman boundary at 10 °C. Two surface phases observed after the cusp points by BAM are pseudo equilibrium state and the global equilibrium is attained with the formation of one condensed surface phase after a long time.

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The iron Lewis acid [η 5 -(C 5 H 5 )Fe(CO) 2 (THF)]BF 4 (1) was found to catalyze reactions of ethyl diazoacetate (EDA) and aromatic aldehydes, yielding 3-hydroxy-2-arylacrylic acid ethyl esters and the corresponding -keto esters. According to the literature, this is the first report of the formation of enol esters from EDA and aromatic aldehydes. The yield of the enol esters increased with electronrich aldehydes. With 2,4-dimethoxybenzaldehyde the only product isolated was the corresponding enol ester in 80% yield. However, in the presence of electron-deficient aldehydes such as p-nitrobenzaldehyde, formation of enol ester decreased to 32%. The most unique feature of these reactions is that enol esters are formed by an unusual 1,2-aryl shift, from a possible intermediate 8, which in turn is formed from the reaction of the iron aldehyde complex 7 and EDA.

Both first- and second-order phase transitions have been studied in adsorbed monolayers of n-hexadecyl phosphate at the air−water interface by Brewster angle microscopy (BAM). An initial plateau region in the surface pressure−time (π−t) curve is caused by a first-order phase transition. This claim is supported by the coexistence of two surface phases which are observed by BAM. A second-order phase transition is indicated by a gradual change in the surface morphology, from a uniformly bright isotropic to an anisotropic mosaic textured phase, which is accompanied by a continuous change in surface pressure. This unusual transition from an isotropic to an anisotropic phase can be understood considering the intermediate nature of the former phase between liquid-expanded and liquid-condensed states.

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