Synthesis, characterization, and biological relevance of hydroxypyrone and hydroxypyridinone complexes of molybdenum

Abstract

We have prepared a number of complexes of the type cis-MoO2L2 where L represents a hydroxypyronato or hydroxypyridinonato ligand. Both the maltol (3-hydroxy-2-methyl-4-pyrone, Hma) and kojic acid (5-hydroxy-2-hydroxymethyl-4-pyrone, Hka) complexes, cis-MoO2(ma)2 (1) and cis-MoO2(ka)2 (2), have been characterized by X-ray diffraction studies. The pyrone ligands are bound to molybdenum in a cis bidentate fashion via the deprotonated hydroxyl groups and the ketone moieties. Crystals of 1 are orthorhombic, a = 12.107 (1), b = 8.6169 (8), c = 16.472 (1) Å, Z = 4, space group Pca21, and those of 2 are monoclinic, a = 8.4591 (5), b = 16.3453 (10), c = 10.2954 (7) Å, β = 103.0320 (10)°, Z = 4, space group P21/c. Hydroxypyridinone molybdenum complexes have been prepared for both maltol and kojic acid derivatives with the substituents Me, n-Pr, CH2Ph, Ph at the ring nitrogen. Crystals of the 3-hydroxy-2-methyl-1-phenyl-4-pyridinone (Hppp) derivative, MoO2(ppp)2 (9), are monoclinic, a = 10.9476 (6), b = 13.5353 (9), c = 17.4877 (10) Å, β = 93.465 (4)°, Z = 4, space group P21/n. Initial investigations into the effects molybdenum compounds have on diabetic hearts are presented. Both Na2MoO4 (used as a control) and 1 were effective in lowering blood glucose and free fatty acid levels. Diabetic rats treated with molybdate showed significant improvements in postischemic cardiac function.Key words: molybdenum, hydroxypyrones, hydroxypyridinones, heart function.

Comparison of anti-hyperglycemic effect amongst vanadium, molybdenum and other metal maltol complexes

“…Like vanadium(IV), molybdenum(VI) is oxophilic, and can form various hydroxypyrone and hydroxypyridinone complexes [41,42]. Both vanadate and molybdate can strongly inhibit protein tyrosine phosphatase activity, thus maintaining tyrosine phosphorylation in protein extracts, although molybdate is less strongly bound in the enzyme active site [43].…”

Preparation and characterization of vanadyl complexes with bidentate maltol-type ligands; in vivo comparisons of anti-diabetic therapeutic potential

“…and ethylmaltol (2-ethyl-3-hydroxy-4-pyrone, Hema), is particularly versatile and effective as ligands for increasing absorption and bioavailability of metal ions, including group 13 metals (Al [1], Ga [2], In [2]), Mo [3], Fe [4], and V [5,6,7]. 3-Hydroxy-4-pyrones typically deprotonate readily, form neutral, thermodynamically stable complexes with appropriately charged metal ions at physiological pH ranges, and are non-toxic.…”

Synthesis, solution and solid state structure of titanium–maltol complex

“…The initial product was characterized by spectroscopic and electrochemical methods. IR spectrum for Ti (maltolato) 2 (OH) 2 shows four bands in the region of 1400-1620 cm −1 , which are typical of coordinated maltol ligand [27,28]. The band at 1660 cm −1 assigned to ν(C=O) in free maltol is shifted to 1620 cm −1 while the combination bands of the ν(C=O) and ν(C=C) vibration modes at 1626 cm −1 and 1565 cm −1 are shifted to 1585 cm −1 and 1518 cm −1 .…”