Ligand Entrapment in Twofold Interpenetrating PtS Matrixes by Metallo-Organic Frameworks

Single-crystal X-ray crystallography was used to determine the structures of four metallo-organic frameworks (MOFs).
A dendritic tetradentate ligand (tetrakis(isonicotinoxymethyl)methane, TINM) was used with first-row transition-metal elements copper, nickel, and cobalt to synthesize MOFs with a PtS interpenetration, due to both planar and
tetrahedral junctions being present in the framework. Two different polymeric complexes, 1 and 2, were obtained
from similar starting materials, TINM and Cu(NO3)2·3H2O, but different solvents. The use of dichloromethane in
addition to methanol and water promoted the coordination of nitrate ions to the copper. With only methanol and
water used as solvent, the copper atom was coordinated to water molecules instead. Compound 1 has pores
going through the structure in two dimensions, along crystallographic axes a and c with diameters of the pores (the
diameters correspond to the minimum distances between van der Waals surfaces of opposing walls defined by
projection along channel axis) approximately 1.0 × 3.1 and 2.5 × 3.7 Å, respectively. Compound 2 has channels
along all crystallographic axes. The dimensions of the channels are 3.2 × 3.7, 3.7 × 5.0, and 2.8 × 4.1 Å, respectively.
The structures of 3 and 4 entrap a large guest ligand molecule in the framework. The guest ligand is uncoordinated,
although the pattern that the entrapped guests form brings the two arms of any two guests within close range. The
lack of 3-fold penetration is due to only two arms being close to each other and also the fact that there is no space
for an additional set of metal centers.