Synthesis, Characterization, Cyclic Voltammetry, and Biological Studies of Co(II), Ni(II), and Cu(II) Complexes of a Tridentate Schiff Base, 1-((E)-(2-Mercaptophenylimino) Methyl) Naphthalen-2-ol (H₂L₁)

Table 4

Electronic spectral data of the ligand and its corresponding complexes.

Compounds	λ (nm) and ν (cm^−1)	ε (L·mol^−1·cm^−1)	Assignments	Suggested structures
H2L1	362 nm (27624 cm^−1)	2901	π ⟶ π	—
	465 nm (21505 cm^−1)	740	n ⟶ π
CuL1	332 nm (30120 cm^−1)	1610	H2L1 chromophore (π ⟶ π)	Square planar
	436 nm (22935 cm^−1)	1113	Charge transfer (L ⟶ M)
	586 nm (17064 cm^−1)	40	^2B1g ⟶ ^2A1g
CoL1	339 nm (29498 cm^−1)	1137	H2L1 chromophore (π ⟶ π)	Tetrahedral
	476 nm (21598 cm^−1)	578	Charge transfer (L ⟶ M)
	640 nm (15625 cm^−1)	176	^4A2 ⟶ ^4T1 (P)
NiL1	329 nm (30395 cm^−1)	626	H2L1 chromophore (π ⟶ π)	Tetrahedral
	453 nm (22075 cm^−1)	772	Charge transfer (L ⟶ M)
	564 nm (17730 cm^−1)	46	^3T1(F) ⟶ ^3T2 (F)