Combining polarized low-frequency Raman with XRD to identify directional structural motifs in a pyrolysis precursor

Area of Science:

• Coordination Chemistry
• Materials Science
• Spectroscopy
• Crystallography

Background:

• Understanding long-range structures and dynamics is crucial in coordination chemistry.
• Experimental identification of these features remains challenging.
• Barium nitrilotriacetate is a metal-organic coordination polymer with applications as a pyrolysis precursor.

Purpose of the Study:

• To experimentally assign Raman peaks to specific long-range motions in barium nitrilotriacetate.
• To investigate the link between precursor structural motifs and the resulting carbon porosity after pyrolysis.

Main Methods:

• Combined polarized low-frequency Raman spectroscopy with single crystal X-ray diffraction (XRD).
• Studied barium nitrilotriacetate, a coordination polymer and pyrolysis precursor.

Main Results:

• Successfully assigned Raman peaks to layer shear motions and perpendicular hydrogen bond vibrations.
• Demonstrated that directional long-range interactions dictate preferred fracture directions during crystallization.
• Established a direct correlation between precursor structural features and the porosity of the derived carbon.

Conclusions:

• The study provides experimental evidence for assigning specific vibrational modes to long-range dynamics in coordination polymers.
• This work links the crystallographic structure of precursors to the microstructural properties of pyrolyzed materials.
• Findings offer insights into controlling carbon material porosity through precursor design.