Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have been one of the most studied materials in recent past and efforts are continuing to uncover their fascinating properties at various levels like gas storage/separation, catalysis, sensing and drug delivery. One of the most intriguing phenomena observed in MOFs is stimuli responsive "dynamic behavior" which can arise either locally from flexible ligands and /or from the global cooperative movement of the frameworks that consequences selective capture or recognition of the specific molecule. Such flexible frameworks shows hysteretic and gated sorption profiles for selective adsobate molecules and also exhibit guest repsonive modulation of opto-electronic and magnetic properties. For example tuning of permanent porosity and modulation of magnetic properties by post-synthetic modification using light in a porous coordination polymer is yet to be accounted. Such synergism, where two different functionalities are combined, would open up the possibility and prospect of finding novel physical phenomena for designing new smart materials. This talk would try to explore some of these stiumuli responsive metal-organic framework systems and their different functionalities.

Secondary building units (SBUs) are molecular complexes and cluster entities in which ligand coordination modes and metal coordination environments can be utilized in the transformation of these fragments into extended porous networks using polytopic linkers (1,4-benzenedicarboxylate, 1,3,5,7-adamantanetetracarboxylate, etc.). Consideration of the geometric and chemical attributes of the SBUs and linkers leads to prediction of the framework topology, and in turn to the design and synthesis of a new class of porous materials with robust structures and high porosity.

The principal structure possibilities for packing infinite rod-shaped building blocks are described. Some basic nets derived from linking simple rods (helices and ladders) are then enumerated. We demonstrate the usefulness of the concept of rod secondary building units in the design and synthesis of metal-organic frameworks (MOFs). Accordingly, we present the preparation, characterization, and crystal structures of 14 new MOFs (named MOF-69A-C and MOF-70-80) of 12 different structure types, belonging to rod packing motifs, and show how their structures are related to basic nets. The MOFs reported herein are of polytopic carboxylates and contain one of Zn, Pb, Co, Cd, Mn, or Tb. The inclusion properties of the most open members are presented as evidence that MOF structures with rod building blocks can indeed be designed to have permanent porosity and rigid architectures.