Electrochemical crystallization of plasmonic nanostructures

We show how gold recrystallizes when under the influence of electrochemical potentials. This "cold annealing" occurs without charge transfer reactions and preserves nanoscale structural features. By performing the process on plasmonic nanostructures, grain growth is monitored noninvasively by optical spectroscopy. In this way, the influence from crystal structure on plasmon resonances can be investigated independently. Observed spectral changes are in excellent agreement with analytical models and changes in electron relaxation time and plasma frequency are calculated.     

Rhodium(II) acetate-catalysed decomposition of 2-diazo-3-oxobutanamides derived from L-phenylalanine

In order to developed a practical method for alkylating α-amino acids at the α- or β-carbon atom by intramolecular carbene C H insertion, a series of diazoamides 3a–e was synthesized and subjected to rhodium(II) acetatecatalysed decomposition. The N-benzyl derivative 3a gave mainly the azetidinones 4a and 5a , resulting from a carbene C H insertion into the N-benzyl group. The N-diphenylmethyl derivative 3c yielded, upon treatment with rhodium(II) acetate, the azetidinone 5c , the imine 6c , the cycloheptapyrrolidinone 7c as well as the desired pyrrolidinone 8c (12% yield) the latter resulting from an alkylation of the L-phenylalanine framework at the β-carbon atom.