Structural Diversity, Magnetic Properties, and Luminescent Sensing of the Flexible Tripodal Ligand of 1,3,5-Tris(4-carbonylphenyloxy)benzene Based Mn(II)/Cd(II) Coordination Polymers

Abstract

Four three-dimensional (3D) Cd(II)/Mn(II) coordination polymers, namely, {[Mn1.5(TCPB)(H2O)(μ2-OH2)]·H2O}n (1), {[Cd3.5(TCPB)2(H2O)3(μ2-OH2)(μ3-OH)]·H2O}n (2), [Mn1.5(TCPB)(bib)0.5(DMF)]n (3), and {[Cd2(TCPB)(HCOO)(bib)(H2O)]·0.5dioxane}n (4), have been constructed from the flexible tripodal ligand of 1,3,5-tris(4-carbonylphenyloxy)benzene (H3TCPB) with or without the help of bib auxiliary linker (bib = 1,4-bis(imidazol-1-yl)benzene). On the basis of the one-dimensional (1D) rod-like {Mn3(COO)8(μ2-H2O)2}n secondary building units (SBUs), complex 1 displays a 3D (4,8)-connected flu net with the point symbol of {412.612.84}{46}2. Complex 2 shows a novel 3D 12-connected {312.440.512.62} net based on the 1D {Cd6(COO)12(μ3-OH)2(μ2-OH2)2}n SBUs. When the bib bridging ancillary linker was introduced, a trinuclear {Mn3(COO)6} SBU based 2-fold interpenetrated 3D (3,8)-connected {43}2{46.618.84}-tfz-d net for 3, and a binuclear {Cd2(COO)3} SBU based 3D (3,7)-connected {4.62}{47.614} net with interesting self-penetrating features for 4 were obtained. Variable-temperature magnetic susceptibilities of 1 and 3 have been investigated. The results display the antiferromagnetic exchange interactions between the adjacent MnII ions of the SBUs in 1 and 3. Fluorescence measurements show 2 and 4 have highly selective and sensitive detection for Cr3+ cations in aqueous solution and nitrobenzene derivatives in DMF.