Abstract
Metal-organic frameworks assembled from Ln(III), Li(I) and rigid dicarboxylate ligand, formulated as [LiLn(BDC)2(H2O)·2(H2O)] (MS1-6,7a) and [LiTb(BDC)2] (MS7b) (Ln = Tb, Dy, Ho, Er, Yb, Y0.96Eu0.04, Y0.93Tb0.07, and H2BDC = terephthalic acid), were obtained under hydrothermal conditions. The isostructural MS1-6 crystallize in monoclinic P21/c space group. While, in the case of Tb3+ a mixture of at least two phases was obtained, the former one (MS7a) and a new monoclinic C2/c phase (MS7b). All compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TGA), vibrational spectroscopy (FTIR), and scanning electron microscopy (SEM-EDX). The structures of MS1-6 and MS7a are built up of inorganic-organic hybrid chains. These chains constructed from unusual four-membered rings, are formed by edge- and vertex-shared {LnO8} and {LiO4} polyhedra through oxygen atoms O3 (vertex) and O6-O7 (edge). Each chain is cross-linked to six neighboring chains through six terephthalate bridges. While, the structure of MS7b is constructed from double inorganic chains, and each chain is, in turn, related symmetrically to the adjacent one through the c glide plane. These chains are formed by infinitely alternating {LiO4} and {TbO8} polyhedra through (O2-O3) edges to create Tb–O–Li connectivity along the c-axis. Both MS1-6,7a and MS7b structures possess a 3D framework with 1D trigonal channels running along the a and c axes, containing water molecules and anhydrous, respectively. Topological studies revealed that MS1-6 and MS7a have a new 2-nodal 3,10-c net, while MS7b generates a 3D net with unusual β-Sn topology. The photoluminescence properties Eu- and Tb-doped compounds (MS5-6) are also investigated, exhibiting strong red and green light emissions, respectively, which are attributed to the efficient energy transfer process from the BDC ligand to Eu3+ and Tb3+.
Highlights
Metal-organic frameworks (MOFs), as an important class of advanced functional materials, have received extensive attention due to their great potential application in various research areas, such as gas adsorption/storage [1,2,3,4,5], liquid separation [6], drug delivery [4,7], and heterogeneous catalysis [8,9,10]
Among different classes of MOFs, lanthanide MOFs (LnMOFs) [11,12,13,14,15], which can be synthesized using a wide range of lanthanide cations and organic ligands, have been investigated in the fields of coordination chemistry, inorganic chemistry, and material chemistry, for their diverse architectures due to high coordination numbers and large ionic radii of lanthanide cations, and for Polymers 2016, 8, 86; doi:10.3390/polym8030086
As an important class of organic ligands, those containing the carboxyl groups that have been applied in the preparation of LnMOFs due to the affinity of lanthanides cations to carboxylate oxygen atoms
Summary
Metal-organic frameworks (MOFs), as an important class of advanced functional materials, have received extensive attention due to their great potential application in various research areas, such as gas adsorption/storage [1,2,3,4,5], liquid separation [6], drug delivery [4,7], and heterogeneous catalysis [8,9,10]. Alkali-based MOFs [36] are not extensively explored, in comparison with transition metals or lanthanide-based MOFs, despite the incorporation of alkali cations into MOFs being an interesting development of MOF chemistry, through exploitation of their various coordination modes, low polarizability, and unique affinity for basic molecules [37,38] Among these compounds, the lithium-based MOFs [39,40,41,42,43,44,45,46] are attracting particular interest due to recent experimental and theoretical studies showing enhanced H2 uptake in lithium doped MOFs [47,48,49,50,51,52,53,54].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Acta Crystallographica Section A Foundations and Advances
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
