Syntheses, structures, photoluminescence, photocatalysis, and photoelectronic effects of 3D mixed high-connected metal–organic frameworks based on octanuclear and dodecanuclear secondary building units†
Abstract
Four novel metal–organic frameworks (MOFs) based on high-nuclear metal carboxylate clusters, namely, [Zn4(L)2(μ3-OH)2(H2O)1.5]·2H2O (1), [Zn5Na(L)2(μ3-OH)4(CH3CH2O)(H2O)2] (2), [Cd4(L)2(BIME)0.5(μ3-OH)2(H2O)1.5]·2H2O (3), and [Zn4(L)2(BET)0.5(μ3-OH)2(H2O)] (4), where H3L = (3,5-dicarboxyl-phenyl)-(4-(2′-carboxyl-phenyl)-benzyl)ether, BET = 1,1′-(2′-oxybis(ethane-2,1-diyl))bis(1,2,4-triazol-1-yl), BIME = 1,2-bis(imidazol-1-yl)ethane, have been synthesized under hydrothermal conditions. In 1, each planar octanuclear zinc cluster [Zn8(μ3-OH)8(CO2)12(H2O)3] is linked by twelve L anions to give an unusual (3,12)-connected framework with (43)2(420·628·818) topology. In 2, dodecanuclear heterometallic clusters [Zn10Na2(μ3-OH)8(CO2)12(CH3CH2O)2(H2O)4] are surrounded by twelve L anions to form a (3,12)-connected net with the same topology as 1. However, 3 exhibits a rare (3,14)-connected (43)(324)(34·420·514·634·711·88) net based on octanuclear cadmium cluster [Cd8(BIME)2(μ3-OH)4(CO2)12(H2O)4]·2H2O as a 14-connected node and H3L as a 3-connected node. In 4, each octanuclear zinc cluster [Zn8(BET)2(μ3-OH)4(CO2)12(H2O)2] is linked by twelve L anions to furnish a (3,14)-connected net with the same topology as 3. The optical energy gaps and photoluminescence were investigated for the compounds. Moreover, compounds 1–4 exhibit good photocatalytic activities for degradation of