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Dr Vennapusa Sivaranjana Reddy
Assistant Professor Grade I (Chemistry)
  +91 (0)471 - 2778057
  siva@iisertvm.ac.in

                              Theoretical and Computational Chemistry

1) Excited State Non-Adiabatic Intramolecular Proton Transfer in Flavonoids

We focus on the study of ultrafast excited state intramolecular proton transfer (ESIPT) in variuos flavones and chromones derivatives like 3-Hydroxyflavone (3-HF), 5-Hydroxyflavone (5-HF) and 3-Hydroxychromone (3-HC) and 5-Hydroxychrone (5-HC). Analysis of spectral features associated with ESIPT enol-keto tautomerization is the first step in our study. As the proton transfer (or tautomerization) occurs on the vibrational motion timescales, potential energy surfaces along each of the O-H vibrational modes are explored using computational techniques. Subsequently, quantum molecular simulations on  computed potentials provide us the mechanistic pathways and timescales of proton transfer.

 

 

 

 

 

 

 

 

 

 

2) Ultrafast Intersystem Crossing in Organic Molecules

Our interests are to identify the pathways involved in an indirect intersystem crossing in molecular systems. Naphthalene, perylenediimide and pyrene derivatives are the model systems currently  under investigation to explore the role of near-degenerate higher singlet-triplet excited states. 

Crossing of two excited state potential enrgy surfaces

 

3) Energy/Electron transfer in large pi-conjugated systems

Evaluation of structural distortions and associated reorganization energies of photoexcited para-linked phenylenes (linear and cyclic) is carried out by DFT and TDDFT methods. Active vibrational modes responsible for excited-state intramolecular vibrational relaxation are to be identified in these molecular systems to provide an accurate description of energy/electron transfer process.