Abstract
Calcium dication has an important role at various stages of blood coagulation mechanism. On the other hand, pindone is an important anticoagulant rodenticide which undergoes 1,3-type proton tautomerism to yield two enolic isomers of pindone. Although, the anticoagulant mode of action of pindone is attributed to blocking of a liver enzyme responsible for the recycling of vitamin K, nothing is known about whether the interaction of it with calcium dication has some role as well. In the present study, the interactions of pindone and its tautomers with Ca++ have been investigated within the restrictions of density functional theory at the level of B3LYP/6-311++G(d,p). It has been found that Ca++ highly affects pindone and its tautomers in many respects at the molecular level, hence their anticoagulation effect should vary.