Stabilization of Curcumin by Complexation with Divalent Cations in Glycerol/Water System

Table 1

Wave length changes of main vibration modes from infrared (KBr pellets) spectral data of curcumin and curcumin complexes. Vibrational modes: (𝜈) stretching; (𝛿) in-plane bending; (---) not observed.

Assignment	𝜈IR (cm^−1)
	Curcumin	Mg-curcumin	Cu-curcumin	Zn-curcumin	Se-curcumin
𝜈^enol(O-H)	3560	—	—	—	—
𝜈^Phenol(O-H)	3600	—	—	—	—
𝜈^Alkene(C-H)	1882	1885	1885	1891	1890
	1857	1865	1860	1868	1865
𝜈^Ketone(C=O)	1762	—	—	—	1738(Δ𝜈=13)
	1725	1800(Δ𝜈=75)	1795(Δ𝜈=70)	1800(Δ𝜈=75)	1778(Δ𝜈=53)
𝛿^enol(C-O)	1406	1402	1402	—	1406
𝛿^Phénol(C-O)	1332	1337	1337	—	1337
	1320	1315	1315	—	1315