Calcium l-Lactate Frameworks as Naturally Degradable Carriers for Pesticides

Two porous, chiral metal-organic frameworks (MOFs), Ca₁₄(l-lactate)₂₀(acetate)₈(C₂H₅OH)(H₂O) (MOF-1201) and Ca₆(l-lactate)₃(acetate)₉(H₂O) (MOF-1203), are constructed from Ca²⁺ ions and l-lactate [CH₃CH(OH)COO^-], where Ca²⁺ ions are bridged by the carboxylate and hydroxyl groups of lactate and the carboxylate group of acetate to give a three-dimensional arrangement of Ca(-COO, -OH) polyhedra supporting one-dimensional pores with apertures and internal diameters of 7.8 and 9.6 Å (MOF-1201) and 4.6 and 5.6 Å (MOF-1203), respectively. These MOFs represent the first examples of extended porous structures based on Ca²⁺ and lactate. They show permanent porosity of 430 and 160 m² g^-1, respectively, and can encapsulate an agriculturally important fumigant, cis-1,3-dichloropropene. MOF-1201 shows a 100 times lower release rate compared with liquid cis-1,3-dichloropropene under the same test conditions (25 °C, air flow rate of 1 cm³ min^-1). The hydrolysis of MOF-1201 in water makes it the first example of a degradable porous solid carrier for such fumigants.