Probing Ion/Molecule Interactions in Aqueous Solutions with Vibrational Energy Transfer

Interactions between model molecules representing building blocks of proteins and the thiocyanate anion, a strong protein denaturant agent, were investigated in aqueous solutions with intermolecular vibrational energy exchange methods. It was found that thiocyanate anions are able to bind to the charged ammonium groups of amino acids in aqueous solutions. The interactions between thiocyanate anions and the amide groups were also observed. The binding affinity between the thiocyanate anion and the charged amino acid residues is about 20 times larger than that between water molecules and the amino acids and about 5–10 times larger than that between the thiocyanate anion and the neutral backbone amide groups. The series of experiments also demonstrates that the chemical nature, rather than the macroscopic dielectric constant, of the ions and molecules plays a critical role in ion/molecule interactions in aqueous solutions

Seven new records of plant in Zhejiang, China(7种浙江新记录植物)

报道了发现于浙江的7种新记录植物，分别是厚叶铁线莲(Clematis crassifolia)、尾叶紫薇(Lagerstroemia caudata)、轮叶赤楠(Syzygium buxifolium var. verticillatum)、毛枝蛇葡萄(Ampelopsis rubifolia)、绒果梭罗（Reevesia tomentosa)、广西地海椒（Physaliastrum chamaesarachoides）和卡开芦(Phragmites karka)

Molecular Conformations and Dynamics on Surfaces of Gold Nanoparticles Probed with Multiple-Mode Multiple-Dimensional Infrared Spectroscopy

Knowledge about molecular conformations and nuclear and electronic motions on surfaces of metal nanomaterials is critical for many applications but extremely difficult to obtain. We demonstrate that valuable information of this sort can be determined using multiple-mode multiple-dimensional vibrational spectroscopy. A model compound, 4-mercaptophenol, on the surface of 3.5 nm gold nanoparticles demonstrates the method. Its 3D molecular conformations and vibrational dynamics on the particle surfaces were determined with the method. The experimental results imply that on the particle surfaces, the ligand molecules cannot form energy-optimized hydrogen bonds because of the surface geometry constraint. The conclusion is supported with experiments on the ligand molecules in the crystalline phase and in a dilute solution. Our experiments also showed that the effect of the particle surface nonadiabatic electron/vibration coupling does not play a significant role in the vibrational relaxation of high-frequency modes (>1000 cm^–1) about 3 Å away from the surface. Simple theoretical calculations support this observation. The method holds promise as a general tool for the studies of molecular structures and dynamics on the surfaces of nanomaterials. The capability of resolving 3D molecular conformations on nanomaterials surfaces is expected to be helpful for understanding specific intermolecular interactions and conformation-selective reactions (e.g., chirality selectivity) on the surfaces of these materials