. 2025 Aug 26;15(37):30102–30122. doi: 10.1039/d5ra03168k

Table 1. Vibrational frequencies (cm⁻¹) and tentative band assignments for DAPH and Ni–DAPH complex.

Wavenumber (cm⁻¹)		Assignment	Observation
Ligand	Complex	Assignment	Observation
3100–3600	3100–3680	O–H	The presence of hydroxyl group is indicated by a broad band indicative of hydrogen bonding. With a sharp bans at 3450 for free ligand disappearing for the complex
3080	2930	C–H	Stretching band for aromatic C–H bonds
1650	1620	C O	Carbonyl band, resulting from conjugation with the ring double bonds, characteristic of coumarins (shifted at a lower wavenumber in the complex)
1440–1600	1450–1600	C C	Aromatic double bonds, observed as multiple bands
1030–1390	1030–1350	C–O	Ester function bands, observed as multiple bands
840	840	C–H	Out-of-plane deformation of the benzene ring

Table 1. Vibrational frequencies (cm−1) and tentative band assignments for DAPH and Ni–DAPH complex.