Two new coordination polymers of Zn(II) and Cd(II) have been synthesized using 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt), where it acts as a bi-bridging ligand. The compounds are characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction studies. Compound [Zn(tpt)(NO₃)₂(H₂O)₂]$_n$ (1) and [Cd(tpt)(NO₃)₂(H₂O)₂]$_n$ (2) are isomorphous and show 1D coordination structure with almost octahedral metal center, which is extended to supramolecular 3D structure by cooperative weak interactions, like H-bonding, $\pi-\pi$ and C-H…O interactions. Both the compounds reveal interplay of covalent and non-covalent interactions for fabricating supramolecular solid-state architecture.

Two new complexes of Mn(II) and Zn(II) have been synthesized using a mixed ligand system and characterized by IR spectroscopy, elemental analysis, single crystal x-ray diffraction and variable temperature magnetic study for one of the compounds. Dimeric coordination structures of [Mn₂(2,4-pyrdc)₂(bpe)(H₂O)₆]·2H₂O (1) and [Zn₂(2,4-pyrdc)₂(azpy)(H₂O)₆]·2H₂O (2) [2,4-pyrdc = 2,4-pyridinedicarboxylate; bpe = 1,2-bis(4-pyridyl)ethane; azpy = 4, 4' azopyridine] are constructed by the bridging of bpe and azpy, respectively and both are extended to a 3D supramolecular structure by non-covalent interactions. In both the cases, unprecedented carboxylate(O)$\ldots \pi$ interactions played a crucial role in the organization of the 3D supramolecular assembly. The carboxylate(O)$\ldots \pi$ interactions are controlled by the C-H$\ldots \pi$ interactions which were accomplished by the proper modulation of the organic linkers. The formation of these supramolecular frameworks revealed that control of weak interactions can be achieved by the interplay of both energetically strong (covalent) and weak forces (non-covalent).

The metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) are a class of porous, crystalline material with numerous possibilities of real-world applications including storage, separation, catalysis, sensing etc. The possibility of intrinsic crystallinity and virtually infinite metal/metal-oxo node and organic linker combination make it a perfect material for photophysical studies. In the last decade, luminescent MOFs have emerged as an excellent modular material for various optical applications, and here, we have discussed about its design strategies. In this review, with relevant examples we have highlighted the rational design approach, possible applications (light emitting diodes, sensing) and future directions in luminescent MOFs