Dimensionality Variation in Polymeric Metallo‐Organic Frameworks

Abstract

Single crystal X-ray crystallography was used to determine the structures of four metallo-organic complexes derived from pyridyl ligands and the metal ions, Cu 2+ , Zn 2+ and Ag + . Two metallo-organic layer framework structures (1 and 3), a strand (2) and a dimer (4) structure were formed when the tetradentate ligands, tetrakis(nicotinoxymethyl)methane (TNM) and tetrakis(isonicotinoxymethyl)methane (TINM), were reacted with the first and second row transition metal cations, copper, silver, and zinc. The choice of anion and ligand was found to affect the outcome of the structure. Contrary to our previous results with the same ligands and similar transition metal cations, no genuine 3D metallo-organic frameworks (MOFs) were obtained. Several factors were found to affect MOF formation: the coordination geometry, the meta-or para-configuration of the coordinating pyridyl moieties and the size and type of the counter anion. In 1, the

Anion Template Effect and the Polymerization Degree – Diversity through Flexibility

“…The use of the Ag I cation resulted in a 2D structure, which was also the case with the use of the Ni II cation. The use of Cu I without the presence of methanol prevented the formation of the Cu-MeOH-Cu bridged structure [12] -a 1D structure was formed instead.…”

“…The frameworks with lower dimensionality are predominantly achieved when using the TNM ligand and the bulky anions BF 4 -and PF 6 -, and also in structures with smaller coordinative anions. [12] Scheme 1.…”

“…In our previous work we presented a noninterpenetrated 2D structure with four TNM ligands coordinated to each Cu II cation. [12] The use of Ag I with two coordination sites for the TNM ligand makes the network of M1 looser: the smallest loop in M1 consists of eight ligand arms plus the metal coordination (56 bonds), whereas in our previous 2D TNM structure, the size of the loop (28 bonds) was half that of the M1. The amount of counter anions per metal cation is also halved in M1.…”

“…We have previously synthesized a 3D MOF from TINM and NiCl 2 [12] and respectively shown that the TNM ligand is unable to form a 3D MOF with a coordinative anion (and without the aid of an additional bridging component). [12,10] However, the formation of structures with lower dimensionality is possible with these components: 1 and 2D structures have already been obtained.…”

“…The pyridyl ligand conformation is eclipsed, as usual for opposing pyridyl ligands ( Figure 2). [12] The Ag2 is "sandwiched" between two neighboring pyridyl rings which are positioned so that an octahedral environment for Ag2 is formed. The Ag2-C distances to the carbons of these pyridyl rings are 3.164 and 3.218 Å.…”