Using linker shapes as a tool to direct MOFs’ dimensionality from 2D to 3D and its morphological study

Pillar-layered Metal Organic Frameworks (PMOFs) [1] are a striking branch of MOF materials which investigating their properties as multi donor porous frameworks is of great interest. Rational design and control of the crystal growth, specifically dimensionality is one important goal for inorganic chemists to be achieved. Whether the resulted networks are one, two or three dimensions the related properties and applicability are different. The most important features of 3D networks are their stability and permanent porosity, while 2D frameworks are interesting for their ultrathin thickness and large surface area with highly accessible active sites. Since the crystal growth in pillar-layered MOFs is a spontaneous self-assembly process, predesign of linkers, for conducting the resulted crystals toward 3D or 2D architectures is promising strategy. Hence, linker modification can act as a favorable method for controlling structure assembly.Here in, for the first time, we report a novel strategy to control the dimensionality, topology and further the morphology of four MOFs through adjusting the linker shapes. Our results interestingly indicate that introducing a v-shaped linker along with a linear one lead to formation of 2D network in TMU-27 [Zn(bpipa)(BDC) and TMU-53 [Zn(bpfb)0.5(IsoBDC)], whereas applying two v-shaped or two linear linkers into the structures produces 3D frameworks TMU-29 [Zn(bpfb)(BDC). 2DMF] and TMU-54 [Zn(bpipa)0.5(IsoBDC)] (BDC: terephthalic acid, Iso-BDC: Isophthalic acid, bpipa: N,N -di(pyridine-4-yl)isophthalamide and bpfb: N,N -bis-(4-pyridylformamide)-1,4-benzenediamine). (Scheme 1)For further investigation on the effect of linker shapes on the MOFs properties, the morphological control of the structures through coordination modulation by different capping agents has been done.