Electrocatalysis by Polyoxometalate-Protected Gold Nanoparticles

Electrocatalysis by polyoxometalate (POM)-monolayer protected gold nanoparticles is herein demonstrated using a newly discovered phenomenon that makes it possible to observe the electrochemistry of dilute aqueous solutions of these colloidal nanostructures. To preserve the integrity of the gold nanoparticles’ electrostatically-stabilized POM-monolayer structures, deposition and drying of the POM-protected metal(0) NPs on the electrode surface must be avoided. Overcoming this constraint, we here show that POM-monolayer protected gold nanoparticles can be induced to reversibly associate with electrode surfaces, resulting in dramatic current amplification and well behaved, quasi-reversible cyclic voltammetric behavior at remarkably small electrolyte concentrations, thus making it possible to investigate electrocatalysis by dilute aqueous solutions of POM-protected gold NPs.     

Folic acid analogs. III. N-(2-[2-(2,4-diarnino-6-quinazolinyl)ethyl]benzoyl)-l-glutamic acid

A trideaza analog of aminopterin, N-(4[2-(2,4-diamino-6-quinazolinyl)ethyl]benzoyl)-L-glutamic acid, was prepared by a Wittig condensation of 2,4-diaminoquinazoline-6-carboxaldehyde and [P-(N-[1,3-bis(ethoxycarbonyl)propan-1-yl]aminocarbonyl)phenylmethyl]triphenylphosphonium bromide followed by catalytic reduction and mild hydrolysis. This compound was found to have confirmed inhibitory activity against leukemia L1210 in mice.     

Synthesis of 1,5-dideazariboflavin

1,5-Dideazariboflavin, an analog of riboflavin containing the original conjugated double bond system between positions 1 and 5, was synthesized by the condensation of 4,5-dimethyl- N-ribitylanthranilaldehyde and the sodium salt of 2,4,6-piperidinetrione.     

2-Azabicyclo[2.2.1]heptane-3-carboxylic acid - A bicyclic proline

Diels-Alder reaction of cyclopentadiene and methyl N-carbobenzyloxy-2-iminoacetate generated in situ from methyl 2-chloro-N-carbobenzyloxyglycinate by triethylamine gave the N-carbobenzyloxy unsaturated bicyclic proline ester. This was converted in two steps to 2-azabicylo[2.2.1]heptane-3-carboxylic acid. In contrast to N-carbobenzyloxy-L-proline methyl ester, the corresponding bicyclic proline ester was resistant to hydrolysis catalyzed by carboxypeptidase Y.     

Molecular constants for NSCl and NSF

The complete infrared spectrum of gaseous NSCl, including the hitherto unobserved ν₃, is reported. A set of force constants for gaseous NSCl consistent with a number of pieces of independent data such as the isotopic shifts (¹⁴N³²S³⁵Cl, ¹⁵N³²S³⁵Cl, ¹⁴N³²S³⁷Cl, ¹⁵N³²S³⁷Cl, ¹⁴N³⁴S³⁵Cl and ¹⁵N³⁴S³⁵Cl), centrifugal distortion constants (¹⁴N³²S³⁵Cl), and the inertia defect (¹⁴N³²S³⁵Cl) has been computed. Also, the force field of NSF has been redetermined using the vibrational frequencies and the centrifugal distortion constants.     

A Convenient Method for the Large Scale Preparation of (E)-4-Oxo-2-Butenoic Acid Ethyl Ester

A one step synthesis of (E)-4-oxo-2-butenoic acid ethyl ester via the reaction of ethyl 2-ethoxy-2-hydroxyacetate and (formylmethylene)triphenylphosphorane is described. The method proceeds in good yield on a molar scale.     

Kinetic modeling of the adsorption rate of a gaseous adsorbate on a granular adsorbent by ultra-rapid-scanning Fourier transform infrared spectrometry

A novel method for determining the rates of adsorption of gaseous adsorbates on granular adsorbents in the millisecond time regime is described. Mixtures of the adsorbate and nitrogen are passed through a solenoid valve and 100 mg of the adsorbent for periods of (typically) 100 ms. The concentration of the adsorbate passing into a low-volume, long path length gas cell is measured with an ultra-rapid-scanning Fourier transform infrared spectrometer capable of gathering 200 mid-infrared spectra per second with 6-cm(-1) resolution. The pressure of the gas entering the cell is measured simultaneously with a capacitance manometer. A dynamic mathematical model was developed to analyze and describe the results in terms of a Langmuir isotherm. The success of this approach is demonstrated by the estimation of the rate of adsorption of vapor-phase acetaldehyde on aminopropylsilylated granular silica gel.