Probing Iodine Atom Interactions in 4-Iodo-L-phenylalanine Crystals by X-Ray Absorption Near-Edge Structure...

Area of Science:

• Solid-state chemistry
• Materials science
• Spectroscopy

Background:

• Crystalline materials containing iodine atoms exhibit unique properties influenced by their atomic arrangements.
• X-ray absorption near-edge structure (XANES) spectroscopy is a powerful tool for probing electronic states and local atomic environments.
• Understanding the relationship between crystal structure and XANES spectra is crucial for materials development.

Purpose of the Study:

• To characterize different crystalline forms of iodine-containing compounds using Iodine L-edge XANES.
• To investigate the influence of atomic interactions on XANES spectral features.
• To establish correlations between specific interactions and spectral responses.

Main Methods:

• Iodine L-edge X-ray absorption near-edge structure (XANES) measurements.
• Single-crystal X-ray structure analysis.
• Analysis of C···I contacts and I···I halogen bonds.

Main Results:

• Each crystalline form of 4-iodo-L-phenylalanine (4ILP) displayed a unique XANES spectral shape.
• Diverse atomic interactions, including C···I contacts and I···I halogen bonds, were identified around iodine atoms.
• Spectral changes at the I L1 edge correlated with van der Waals contacts, while L2 and L3 edges responded to halogen bonds.

Conclusions:

• Weak nonconventional atomic interactions critically impact XANES spectra.
• Iodine L-edge XANES is sensitive to subtle structural variations and intermolecular forces.
• This study provides insights for designing and evaluating crystalline materials based on their XANES signatures.