Catalytic, Antifungal, and Antiproliferative Activity Studies of a New Family of Mononuclear [V IV O]/[V V O 2 ] Complexes.

Ligands derived from 2-(1-phenylhydrazinyl)pyridine and salicylaldehyde (HL ¹ ), 3-methoxysalicylaldehyde (HL ² ), 5-bromosalicylaldehyde (HL ³ ), and 3,5-di- tert -butylsalicylaldehyde (HL ⁴ ) react with [V ^IV O(acac) ₂ ] in MeOH followed by aerial oxidation to give [V ^V O ₂ (L ¹ )] ( 1 ), [V ^V O ₂ (L ² )] ( 2 ), [V ^V O ₂ (L ³ )] ( 3 ), and [V ^V O ₂ (L ⁴ )] ( 4 ). Complex [V ^IV O(acac)(L ¹ )] ( 5 ) is also isolable from [V ^IV O(acac) ₂ ] and HL ¹ in dry MeOH. Structures of all complexes were confirmed by single-crystal X-ray and spectroscopic studies. They efficiently catalyze benzyl alcohol and its derivatives' oxidation in the presence of H ₂ O ₂ to their corresponding aldehydes. Under optimized reaction conditions using 1 as a catalyst precursor, conversion of benzyl alcohol follows the order: 4 (93%) > 2 (90%) > 1 (86%) > 3 (84%) ≈ 5 (84%). These complexes were also evaluated for antifungal and antiproliferative activities. Complex 3 with MIC ₅₀ = 16 μg/mL, 4 with MIC ₅₀ = 12 μg/mL, and 5 with MIC ₅₀ = 16 μg/mL are efficient toward planktonic cells of Candida albicans and Candida tropicalis . On Michigan cancer foundation-7 (MCF-7) cells, they show comparable cytotoxic effects and exhibit IC ₅₀ in the 27.3-33.5 μg/mL range, and among these, 4 exhibits the highest cytotoxicity. A similar study on human embryonic kidney cells (HEK293) confirms their less toxicity at lower concentrations (4 to 16 μg/mL) compared to MCF-7.