Saptarshi Biswas (Rishi)
My research is centred on understanding the fundamental photophysics of Earth-
abundant transition metal complexes, specifically Iron(II), with the ultimate goal
of advancing sustainable energy conversion technologies.
The core of my work involves investigating the ultrafast excited-state
deactivation pathway of Fe(II) complexes. This pathway involves a quantum
mechanically forbidden spin-state change (ΔS=2), making them both
fundamentally intriguing and crucial to controlling energy flow in these systems.
A detailed mechanistic understanding of this process is essential for the rational
design of iron-based photosensitizers for solar energy applications.
To gain this understanding, I am studying a series of Fe(II) complexes derived
from [Fe(2,2’-bipyridine)
3
]
2+
. This series allows us to systematically tune the
molecule's ability to distort along low-frequency torsional degrees of freedom.
These symmetry-breaking motions are key, as they introduce new "avoided
crossings" in the molecular potential energy surface, which act as gateways for
the critical state-to-state interconversion. By systematically varying the
molecular structure, we can gain unique insights into how these motions influence
quantum mechanical state mixing and ultimately govern the deactivation
dynamics.
My broader goal is to build a comprehensive picture of how structural and
electronic factors govern the deactivation process, enabling the rational
manipulation of these dynamics. This fundamental knowledge is critical for
contributing to the development of iron-based photosensitizers for sustainable
energy applications.
