Effects of the Alkali-Metal Cation Size on Molecular and Extended Structures: Formation of Coordination Polymers and Hybrid Materials in the Homologous Series [(4-Et-C₆H₄OM)·(diox)_n], M = Li, Na, K, Rb, Cs

Abstract

The complete series of group 1 metal 4-ethylphenoxide (4-Et-C(6)H(4)O(-)) networks have been synthesized using 1,4-dioxane (diox) as a neutral linker. [{(4-Et-C(6)H(4)OLi)(4)·(diox)(2.5)}·diox](∞) (1) and [{(4-Et-C(6)H(4)ONa)(6)·(diox)(3)}(∞)] (2) form 2D and 3D networks, respectively, composed of discrete aggregates linked by diox. Compound 1 forms a hexagonal layered structure with Li(4)O(4) cubanes acting as nodes, whereas compound 2 forms a primitive cubic network (pcu) with Na(6)O(6) hexameric nodes. [{(4-Et-C(6)H(4)OK)(3)·diox}(∞)] (3), [{(4-Et-C(6)H(4)ORb)(2)·(diox)(0.5)}(∞)] (4), and [{(4-Et-C(6)H(4)OCs)(2)·(diox)(0.5)}(∞)] (5) are composed of isostructural 1D inorganic rods that are linked through diox to form pcu-type networks. Compound 5 is the first example of a network built from cesium inorganic rods.

Framework Complexes of Group 2 Metals Organized by Homochiral Rods and π···π Stacking Forces: A Breathing Supramolecular MOF

“…The most prominent structural feature of this work, especially when coupled with our previous paper on group 1 metals with the same ligands, is the consistent formation of rod SBUs, rods that are necessarily homochiral because of building the ligands from enantiopure amino acids. The s-block metals generally lack the formation of consistent SBUs as one varies the metals, although it has been pointed out recently that the larger metals of group 1 are likely to form rod structures with anionic oxygen donor ligands . With our ligands containing the large, π···π stacking naphthalimide group, we consistently observe rods with both group 1 and 2 metals even though the rods are built from a variety of bridging oxygen donor motifs, including cases where the only bridge comes from the solvent.…”

“…The s-block metals generally lack the formation of consistent SBUs as one varies the metals, 12 although it has been pointed out recently that the larger metals of group 1 are likely to form rod structures with anionic oxygen donor ligands. 16 With our ligands containing In four of the five compounds (1, 3, 4, and 5), each rodshaped SBU is interlocked with four adjacent rods through π•••π stacking in a motif similar to the uninodal 4c net if they were covalent connections. In 2, the naphthalimide rings for one rod are oriented in a position where two pairs of naphthalimide rings interdigitate with two pairs on two adjacent rods resulting in 2D sheets instead of a 3D network.…”

New Lithium Ion Clusters for Construction of Porous MOFs

“…For Li + , the clustering could provide a new route for synthesizing Li-MOF from more negative carboxylate ligands. The challenge is, however, that known lithium clusters are generally formed with anionic species [e.g., Li 4 (PhO) 4 ] and are neutral . We are thus very interested in synthetic possibilities that can lead to positive lithium clusters.…”

“…Compared to MOFs based on other lightweight elements, significantly fewer Li-MOFs (MOFs based on pure Li nodes) are currently known, even though some progress has been made. − This is apparently due to lithium’s unique combination of hard Lewis acidity and low +1 charge. Other metal ions with a low +1 oxidation state (such as Cu + and Ag + ) are much softer than Li + and often derive their relatively rich coordination chemistry through their soft acid property …”

A metal–organic framework assembled from Y(iii), Li(i), and terephthalate: hydrothermal synthesis, crystal structure, thermal decomposition and topological studies

“…Since the coordination numbers and geometries of alkali cations are unpredictable, but their coordination nature may depend on the size and the nature of the ligands. 65 So, the main cause of the structural differences between compound type S1 and the new compound 1 is attributed to the small size of the Li + cation unable to satisfy the more chelating centers of Tart compared with BDC.…”