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Ultrafast Dynamics in Molecules and
Nanomaterials
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The focus of the research in our Group is on the
study of the dynamics of ultrafast processes that are of importance in
Chemistry and Biology. The principal tools we use for this process are steady state and femtosecond-nanosecond time
resolved fluorescence spectroscopy. We also use techniques like
light scattering, Tunneling Electron Microscopy, Circular dichroism and
Confocal Microscopy. A brief account of our present research activities and
interests is provided below. (a)
Excited State Processes in Neat Solvents and
Restricted Microenvironments This has been the principal strength
of our group in the past years. We have investigated the excited state
dynamics of novel fluorophores like epicocconone and Lucifer yellow, with an
emphasis on how they are affected by the properties of the microenvironment
around the fluorophore. In the course of these studies, we have explored the
role of confined water as well as charged interfaces on the dynamics of
solvent mediated excited state proton transfer in 2-(2’-pyridyl)benzimidazole.
This has led us to propose potential applications of this fluorophore in the
study of macromolecular interactions, intracellular fluorescence imaging and
water content in polymers. The changes in photophysical pathways, brought
about by synthetic modification of some fluorophores, are being studied at
present. d(b)dddPorphyrins and
Chlorins Porphyrins and chlorins are an
important class of compounds that are central to important biological
processes such as photosynthesis and storage and transport of oxygen. We have
performed systematic studies of aggregation and photoinduced electron
transfer of chlorin p6, which has led us to a series of
experiments on the dynamics of ultrafast processes in novel chlorin-based
systems. The purpose of these studies is to mimic photosynthetic processes
and produce efficient devices for charge transport and energy storage.
Another interesting aspect of these compounds is their potential application
as drugs for photodynamic therapy (PDT). In order to understand their suitability
in this application, it is imperative to study their aggregation properties,
binding with drug delivery vehicles and cellular uptake. Such investigations
are presently in progress. (c)ddd Fluorescence Sensing of Biologically
Relevant Analytes Fluorescence is a sensitive technique
for detection of minute amounts of analytes, which has the potential to
eliminate costly and hazardous radioactive tracers. We attempt to develop and
characterize novel fluorescent sensors for analytes like chloride ions,
oxygen and metal ions in trace quantities. We have investigated quinolines
for sensing of halide ions with emphasis on ion-specificity and the effect of
counterions. Efforts are on to develop and characterize novel sensors with
high specificity and selectivity. (d)ddd Ultrafast Moelcular Devices and
Photoluminescent nanomaterials We have ventured into these fields in recent times. Presently, we
endeavour to understand the origin of photoluminescence of silica
nanoparticles. Future plans include their modification by labeling with
fluorescent dyes, with the motivation of preparing ordered structures using
the nanotubes as templates. Such ordered structures are likely to behave as
light-harvesting nanoantennae, with additional possibilities of application
as nanobiosensors and targeted drug delivery vehicles. |
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