Takayuki Ebata

TL;DR: Size-dependent development of the hydrogen bond network structure in largesized clusters of protonated water, H+(H2O)n, was probed by infrared spectroscopy of OH stretches by demonstrating that the chain structures at small sizes develop into two-dimensional net structures and then into nanometer-scaled cages.

TL;DR: In this paper, the authors report UV photodissociation (UVPD) and IR-UV double-resonance spectra of dibenzo-18crown-6 (DB18C6) complexes with alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) in a cold, 22-pole ion trap.

Abstract: Infrared (IR) spectra of benzene–(water)n cluster cations (Bz–Wn)+ (n=1–6) in the OH and CH stretching vibrational region were observed in order to investigate their structure and reactivity The cluster cations were prepared by two different production methods: one is due to collision between bare benzene cations and water clusters; and the other utilizes resonance enhanced multiphoton ionization (REMPI) of neutral clusters The former method prefers the production of the most stable isomer cluster cations, while the latter would reflect the Franck-Condon restriction in the ionization process The structures of the n=1 and n=2 clusters were determined on the basis of the comparison between the IR spectra and density functional theory (DFT) calculations In the n=1 cluster cation, the oxygen atom of the water molecule is located in the benzene ring plane and coordinates to the benzene moiety by two identical CH–O hydrogen bonds The IR spectra of the n=2 cluster cation showed absorption bands arising from two different types of isomers: one has a hydrogen-bonded water dimer interacting with the benzene cation; in the other isomer two water molecules are independently bound to the benzene cation The production ratio between the isomers was found to strongly depend on the cluster ion preparation methods Except for the case of the n=2 cluster, the cluster cations prepared by the two different methods gave identical IR spectra This means that quite extensive rearrangements of the cluster structure occur upon ionization of the neutral clusters, leading to the most stable form of the cluster cations The spectral features of the n=3 cluster cation are very similar to the n=2 cluster, suggesting similar structures among these clusters Higher clusters larger than the n=3 cluster showed quite different IR spectra from those of the n≤3 clusters, but their spectral features are very similar to those of hydrated clusters of protonated species, X–H+–(H2O)n, indicating that proton transfer reactions from the benzene cation to the water moiety occur in the larger clusters than those with n=3

TL;DR: The laser-induced fluorescence spectrum of jet-cooled L-tyrosine exhibits more than 20 vibronic bands in the 35450-35750 cm(-1) region and IR-UV spectra suggest that conformers belonging to two of the four groups have an intramolecular OH...N hydrogen bond between the COOH and NH2 groups.

TL;DR: In this paper, the activation of the activated CH/π interaction between an acidic CH group and π-electrons was studied in order to characterize the intermolecular interaction between the activa...