Chromium tricarbonyl complexes η6-bonded to 3-amino-9-ethylcarbazole at either the NH2-substituted aryl ring (1) or the unsubstituted aryl ring (2) have been synthesized and their UV-visible absorption spectra determined. In comparison to 2, 1 causes a subtle blue shift in the metal-to-ligand charge-transfer band along with spectral shape changes due to electron transfer from the NH2 substituent to the Cr(CO)3 center.

Two-dimensional correlation spectroscopy has been applied to study PMPCS (poly{2,5-bis[(4- methoxyphenyl)-oxycarbonyl]styrene}), a representative example of mesogen-jacketed liquid crystalline polymers. With the precise analysis of a series of Fourier transform infrared (FTIR) spectra of PMPCS recorded at varied temperatures, a reasonable mechanism of the development of liquid crystalline (LC) phase is proposed. Before the phase transition, the conformational change of individual side chains occurs sooner than that of the backbone due to the larger motional freedom of the side chains. After the phase transition, however, the readjustment of still somewhat mobile backbone occurs before the ordered, rigid, and mutually interacting side chains. That is, phase transition leading to the LC phase formation brings in a new cooperative restriction of motions to the segments.

We used two-dimensional (2D) correlation infrared spectroscopy to study further the potassium-induced conformation transition in Nephila spidroin films. It provided increased resolution and important new information on the sequence of events in the conformation transition process, showing that â-sheet formed from the helical component before they formed from random coil. It also showed more evidence that formation of the 1691cm-1 (turn/bend) peak did not proceed with the same kinetics as the 1620cm-1 (antiparallel â-sheet component) one, so we attribute the 1691cm-1 peak to turns which formed with different kinetics as the antiparallel β-sheets. We present a single coherent and detailed hypothesis for the assembly and secondary structural transition of silk proteins in vivo and in vitro based on our findings and on evidence from other laboratories.

The diffusion of different deuterium-labeled (OD) low-molecular-weight alcohols and D2O in Nylon 11 has been investigated by monitoring the NH/ND exchange in the polymer by Fourier transform near-infrared (FTNIR) spectroscopy. The results demonstrate that the diffusion process of the different penetrants is strongly controlled by their molecular structure and geometry. To characterize this phenomenon quantitatively, the diffusion coefficients for the different deuteration agents have been determined for Nylon 11. The rate of the diffusion was found to decrease with increasing size of alcohol. Furthermore, it could be shown that with this technique the less ordered regions of the polymer can be separated spectroscopically from the crystalline domains, which are not accessible for the isotopically labeled diffusants.

Raman spectra of a polythiophene film measured over a temperature range 298-98K were analyzed using generalized two-dimensional correlation spectroscopy. In the 1600-1250cm-1 region, the asynchronicity of the bands indicates the existence of different species in the investigated polythiophene sample. At least four distinct bands at 1485, 1454, 1418, and 1360cm-1 were identified. Among them, the band at 1454cm-1, attributed to the neutral species of PTh, is found to be sensitive to the temperature-induced structural changes of the polythiophene film, while the bands of the oxidized species are less sensitive to the temperature change during the cooling process.