Single molecule magnets (SMMs) are an important class of bistable magnetic molecules having potential applications in memory devices, quantum computing (qubits), molecular spintronics, magneto-optics, etc. Such magnetic molecules exhibit slow relaxation of magnetization, which is purely of molecular origin. Hence, designing SMMs possessing practical application happens to be an important aspect of modern research. One of the major prerequisites for obtaining excellent SMMs is introducing a highly axial symmetry coordination environment which results in high magnetic axiality of the metal ion, thereby generating a pure bistable ground state. Basic transition metal coordination chemistry is very essential to the design and synthesis of these interesting classes of complexes. 

Particularly, our group aims to design low as well as high-coordinated SMMs having high Ueff and blocking temperature by modulating the coordination environment around the metal ions. Further, we explore the relaxation dynamics of SMMs by performing the ab initio calculations.

For the responsive molecular materials, we mostly design Hofmann-type and reverse-Hoffmann-type coordination polymers. These are the highly networked porous frameworks linked through covalent bonds exhibiting strong cooperativity between the SCO sites. The structural and magnetic properties of this class of CPs can be tuned by careful design of the bridging ligands, and the cyanometallate units or guest incorporation inside the framework. Elegant framework design, excellent thermal and chemical stability, spin-state switching by various stimuli such as temperature, pressure, light irradiation, and guest incorporation are key factors accounting for our fascination for these coordination polymers. 

The transition towards nanoparticles from microcrystals is a defining step for potential technological applications of these smart, multifunctional molecules. The degradation of SCO behavior on size reduction is a key challenge associated with size miniaturization. Also, the appealing magnetic properties of the Hofmann type coordination polymers can be better exploited for practical applications if these frameworks are fabricated as thin films.

Our objectives include the synthesis of novel HCPs at the microscale, nanoparticles exhibiting hysteretic and abrupt spin transition, and fabrication of polymer-based composite films harnessing the synergy between two components in a bid to bridge the gap between the laboratory and reality.

ETCST is a phenomenon that involves electron transfer between two metals, accompanied by a spin transition in one of the metal centers. The reversible electron transfer between the Co and Fe centers in Fe/Co Prussian blue analogs (PBAs) renders switchability to this class of magnetic molecules. The hysteretic and reversible switching of the electronic states of these molecules directs their use in data storage devices and molecular switches. The realization of reversible ETCST depends on various external factors such as the ligand field, choice of counter anions, lattice solvent molecules, etc. These factors influence the redox potentials around the metal centers, which govern the electron transfer. Our interest lies in designing molecules exhibiting temperature, pressure, and/or photo-induced ETCST behavior and maneuver them for multiple applications. We are working to optimize the factors controlling the ETCST behavior to explore the exciting aspect of these molecules under ambient conditions. 

Polyoxometalates (POMs) can be viewed as large metal oxide clusters of high valent transition metals. They can accommodate magnetic ions or groups of magnetic ions at specific sites of the rigid POM structure, resulting in molecules with unique magnetic characteristics. POM ligands provide several advantages compared to their organic counterparts, including the steric bulk of the POM reducing undesirable intermolecular interactions, the accessibility of nuclear spin-free isotopes to reduce quantum tunneling, and the provision of coordination geometries and crystal fields. Different POM complexes show great promise for catalytic conversion of carbon dioxide to fuel and water splitting processes. Along with magnetic properties, we look forward to expanding our research further into such domains as well.

We use molecular self-assembly for the intricate design of complex metallosupramolecular architectures to achieve magnetic switching (both in solid and solution states). Although an array of products is possible by this template-directed self-assembly, only a small number of architectures are stable. The central challenge is, thus, to find out the dynamic equilibrium governing these structures, and use them to tune the notion of cooperativity, which governs the overall magnetic response. Most interestingly, in presence of an external physical stimulus, generation of radical ions couples the electronic properties to external functions, making them an appropriate candidate for smart materials.