Modification of Network and Pore Dimensionality in Metal-Organic Frameworks Containing a Secondary Phosphine Functionality

Three new metal-organic frameworks containing a triphenylphosphine moiety, namely, [Zn-3(tpp)(2)(DMP)(2)] nDMF (1), [Zn-3(tpp)(2)(4,4'-bpy)(2)].nDMF (2), and [Zn-3(tpp)(2)(3,31-bpy)].nDMF (3), were synthesized using 4,4',4"-phosphanetriyltribenzoic acid (H(3)tpp) as a tritopic linker. The absence or presence of additional N-donor linker molecules in the reaction mixture lead to the formation of (3,6)-c layered, (3,8)-c pillared layered, or (3,4,6)-c framer works. Compound' 1 is composed of a trinuclear zinc secondary building unit (SBU) and the tpp(3-) anion arranged in a layered (3,6)-c network with kgd topology. There are DMF guest molecules coordinated to the terminal Zn atoms of the trinuclear inorganic SBU. The addition of the neutral N-donor molecules 3,3'-bipyridine (3,3'-bpy) and 4,4'-bipyridine (4,4'-bpy) as second organic linker molecule lead to an increase of dimensionality.of the networks. Compound 2. is 'a (3,4,6),-nodal threedimensional MOP. Its structure consists of two equivalent-nterpenetrated nets with the point symbol (5(2).6(4))(5(2).6)2(5(4).6(6).7(2).8.9(2)) containing solvent filled pockets. The free electron pair of the phosphorus atom of the triphenylphosphine moiety is pointing toward the zero-dimensional pores. The structure of 3 can be described layers of 1 which are connected by 3,3'-bipyridine as contains a solvent filled three-dimensional pore system. All three materials exhibiOaptake of CO2 at 195. K after removal of the the point symbol (4(3))(2)(4(6).6(18).8(4)).pillar into a three-dimensional (3,8)-c. network with The non-interpenetrated structure of 3 guest DMF molecules. This is particularly surprising for 2, with its zero-dimenSional pores in the single-crystal structure and absence of N-2, adsorption at 77 K. Compound 3 shows alarge gate opening effect for CO2 adsorption at 195 K.