Discriminability of tryptophan containing dipeptides using quantum control

We show that the coherent manipulation of molecular wavepackets in the excited states of trp-containing dipeptides allows efficient discrimination among them. Optimal dynamic discrimination fails, however, for some dipeptide couples. When considering the limited spectral resources at play (3nm bandwidth at 266nm), we discuss the concept of discriminability, which appears uncorrelated to both static spectra and relaxation lifetime

In Situ ATR-FTIR Investigation of Photodegradation of 3,4-Dihydroxybenzoic Acid on TiO2

The catalytic photo-oxidation of 3,4-dihydroxybenzoic acid on TiO2 has been studied by in situ ATR-FTIR in flowing water and in flowing wet air/nitrogen gas. In flowing water it was difficult to observe photodegradation intermediates despite photocatalytic action during UV illumination. In the flowing wet air/nitrogen system carboxylic acids and carbonates were observed. It was shown that water plays an important role in the formation of oxidation active species. Oxygen shows a prominent role for carboxylic acid degradation, but the photogenerated hole plays the important role for the 3,4-dihydroxybenzoic acid ring cleavage

Functionalized silicate nanochannels: towards applications in drug delivery and solar energy conversion

The defined pore networks of silicate-based molecular sieves are attractive for the development of highly organized inorganic/organic hybrid materials. Efficient energy transfer systems are obtained upon inclusion of dye molecules into the one-dimensional channels of zeolite L. The resulting host-guest materials form the basis for an advanced luminescent solar concentrator. The selective functionalization of the channel entrances with zinc phthalocyanine offers further possibilities in terms of employing the dye-zeolite composites for the sensitization of organic solar cells. Having larger pore sizes than zeolites as well as highly modifiable channel walls, mesoporous silicas have recently emerged as versatile starting materials for the synthesis of drug delivery devices. One of the most challenging aspects in this context is the control and the analysis of the functional group distribution. This topic is discussed on the basis of our recent work on the reaction of aminopropylalkoxysilanes with mesoporous silica MCM-41

In Situ ATR-IR Study on the Photocatalytic Decomposition of Amino Acids over Au/TiO 2 and TiO 2

The photocatalytic degradation of l-asparagine and l-glutamic acid over Au/TiO2 and TiO2 catalysts was investigated in situ by attenuated total reflection infrared (ATR-IR) in combination with modulation excitation spectroscopy. Oxalate was detected on the catalyst surface, which has not been reported before for degradation of amino acids by studies focusing on intermediates in solution. The ATR-IR spectra provide valuable information on the fate of the nitrogen. Ammonium was detected, in agreement with previous studies. Most importantly, strong signals of cyanide were observed, and this assignment has been corroborated by 15N labeling experiments. Cyanide was not reported before, to the best of our knowledge, for the photocatalytic degradation of amino acids. Cyanide was formed in the presence and the absence of gold particles on the TiO2 surface. The cyanide leads to leaching of gold via Au(CN)2− species that were detected in solution by mass spectrometry

Adsorption and stability of malonic acid on rutile TiO2 (110), studied by near edge X-ray absorption fine structure and photoelectron spectroscopy

The adsorption of malonic acid on rutile TiO2 (110) has been studied using photoelectron spectroscopy and C K-edge, near edge X-ray fine structure spectroscopy (NEXAFS). Analysis of the O 1s and Ti 2p spectra suggest that the molecule adsorbs dissociatively in a doubly-bidentate adsorption geometry as malonate. The data are unable to distinguish between a chelating bonding mode with the backbone of the molecule lying along the [001] azimuth or a bridging geometry along the direction. Work carried out on a wiggler beamline suggests that the molecule is unstable under irradiation by high-flux synchrotron radiation from this type of insertion device