Surface-enhanced ATR-IR spectroscopy with interface-grown plasmonic gold-island films near the percolation threshold

Flat nano-island films prepared by wet-chemical deposition were investigated with attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) in order to analyze the correlation between film morphology and optical properties. Here we choose Au as representative coinage metal (Au, Ag, Cu) that shows strong structure-dependent surface-enhanced infrared absorption (SEIRA). Infrared spectra of octadecanethiol monolayers on films of different stages of morphologic development show effects that are characteristic for SEIRA, such as enhanced vibrational signals, Fano-type line shape, and adsorbate induced baseline shifts. Their extent was found to be strongly dependent on the structural details and the strongest enhancement occurs at the percolation threshold of the two-dimensional island system. Also films beyond percolation show significant enhancement due to residual nanoholes that are acting as hotspots.     

Photochemical control of a highly efficient addition reaction between electron-rich alkynes and tetracyanoethylene

The electron density of an alkyne moiety is enhanced by the photochromic ring closure of a diarylethene derivative, which allows the thermal addition reaction with a small π-acceptor, tetracyanoethylene, at room temperature.     

Photochemical control of dielectric properties based on intermolecular proton transfer in a hydrogen-bonded diarylethene crystal

The photochromic reaction of a diarylethene derivative having imidazoline rings reversibly modulates the dielectric properties of the crystal, which is based on the intermolecular proton transfer in one-dimensional (1D) hydrogen-bonded chains.     

Anchoring of 1,8-naphthalimide derivative into mesoporous MCM-41 molecular sieves

The fluorescent dye molecules, 4-piperidine-1,8-naphthalimide, were successfully fixed into the amino modified pore channel of mesoporous MCM-41 type materials by in situ reaction of 4-piperidinyl-1,8-naphthalic anhydride with the amino group. The formation of amide bonds on the pore surface was verified by infrared spectra. The maximum fluorescence emission peak of this hybrid material has a red shift of 13 nm compared to that of a naphthalimide derivative in ethanol solution. Moreover, the fluorescence intensity of dye molecules grafted into Ce-doped MCM-41 is higher than that in pure silica MCM-41. This phenomenon is attributed to the inhibited internal electron transfer from piperidine to naphthalimide groups by Ce⁴⁺, thus improving the fluorescence intensity of the naphthalimide group. The unique fluorescence behavior of the 1,8-naphthalimide derivative doped hybrid mesoporous material makes it a good candidate for the metal ions microdetection.     

Design of a stabilized short helical peptide and its application to catalytic enantioselective epoxidation of (E)-chalcone

Stabilized short helical heptapeptides containing a combination of an α-aminoisobutyric acid as a helical promoter and l/d-serine derivatives to produce cross-linked units were synthesized. The cyclic peptide R₃,₇R-2, which had d-serine derivatives at its 3rd and 7th positions, formed a stable right-handed (P) α-helix in solution and the crystalline state. Furthermore, its N-terminal free helical peptide catalyzed the enantioselective epoxidation of (E)-chalcone to afford the epoxide in a high yield and moderate enantioselectivity.     

铜离子交换分子筛上NO吸附的IR光谱及TPD研究

采用原位IR光谱及TPD技术研究了NO在铜离子交换分子筛上各种表面物种的生成及脱附,并与NO在Cu-ZSM-5上的分解反应性能相关联,考察了Cu-ZSM-5反应活性高的原因及O₂的生成机理。NO的吸附状态随分子筛母体种类及铜离子交换度的不同而变化,交换度较高的ZSM-5催化剂上容易形成NO-3物种,该物种对NO分解及O₂的生成具有重要作用。     

Synthesis,Structure, and Spectroscopic Properties of [Feiii(tnpa)(OH)(PhCOO)]ClO4: A Model Complex for an Active Form of Soybean Lipoxygenase-1

The cis configuration between the hydroxo and the carboxylato and the three amino groups of the tetradentate, tripodal ligand tris(6-neopentylamino-2-pyridylmethyl)amine favors the formation of hydrogen bonds which stabilize the hydroxo–Feⁱⁱⁱ complex 1 . Thus, its structure closely resembles that of the active center of Feⁱⁱⁱ –soybean lipoxygenase-1, which also contains a six-coordinate Feⁱⁱⁱ atom.     

A Kinetically Stabilized [1.1]Paracyclophane: Isolation and X-Ray Structural Analysis

Benzene rings severely bent and closely stacked face-to-face are revealed in the crystal structure of the [1.1]paracyclophane derivative 1 , which could be isolated thanks to the kinetic stabilization provided by the steric shielding of the bridgehead sites by the substituents.