Fig. 8. Vibrational spectroscopy analysis of compounds 1a and 4a.

a Raman spectra (acquired with a 785 nm laser) of 1a recorded at 323 K (red), 193 K (blue), and 93 K (yellow); b Raman spectra (acquired with a 785 nm laser) of 4a recorded at 283 K (red), 243 K (blue) and 133 K (yellow); c temperature dependent Infrared absorption spectrum of compound 1a and d temperature dependent Infrared absorption spectrum of compound 4a.