Spectroscopic Investigations in Chiral Crystalline and Solution Phases

Chirality is an interesting phenomenon that is not completely understood, and the present work broadens the present body of knowledge using various methods. Crystallization experiments of glycine have confirmed the previously reported phenomenon of nonphotochemical laser induced nucleation (NPLIN), and experiments utilizing a geometry with focused lasers may also display NPLIN, though the results indicate that new factors such as pH of the irradiated solution may affect the crystallizing process. Sodium bromate, NaBrO₃, may also crystallize via NPLIN, though the results are not as conclusive as the glycine experiments. For both glycine and sodium bromate, sound waves produced micron sized crystals of high quality.

The optical rotatory dispersion (ORD) curve of sodium chlorate and sodium bromate was recorded, and good agreement was found with previous literature. Laser light with a sufficient intensity gave rise to non-linear effects (NL-ORD) in the optical rotation. The NL-ORD was composed of a main contribution from n₁, but multi-photon contributions, nn₁, affected the optical rotation.

The compressibility of racemic and enantiomerically pure a-methylbenzylamine was measured using a novel apparatus, and low frequency intermolecular vibrations measured via Raman spectroscopy gave good agreement with the magnitude of the compressibility. The compressibility of the enantiomerically pure a-methylbenzylamine was slightly higher than the racemic solution.

The ORD of (S)-(a)-methylbenzylamine was recorded in a series of 39 solvents with widely ranging solvent properties. Calculations of the optical rotation via Gaussian03 were insufficient in describing the solvent effect upon the optical rotation. A good correlation of the optical rotation and the Kamlet-Taft parameters (a, b, p^*) was established, and good agreement was found between the predicted model and the experimental results.

Spectroscopic characterization of a-methylbenzylamine over the entire mole fraction concentration range in five distinct solvents (cyclohexane, toluene, nitrobenzene, DMSO, and methanol) via FTIR and NMR helped illuminate mitigating factors affecting the optical rotation. The nitrogen site was the only contributor that dominantly affected the optical rotation in the selected solvents.