The Banerjee Research Group
Supramolecular and Functional Organic Materials Lab
Department of Chemical Sciences
IISER Kolkata
Research Areas
The main objective of our group is to design small functional organic molecules for diverse applications in chemistry and materials. We employ multi-step organic synthesis to create functional building blocks and study their self-assembly. Such self-assembled materials are responsive and adaptive to external stimuli and as a result, they find a range of potential applications in sensing, light-harvesting, in the design of biomaterials and hybrid materials, in optoelectronics, etc. Currently, we are focusing on the following areas.
Luminescent Supramolecular Polymers in Aqueous Media
We design amphiphilic molecules based on chromophoric moieties and use their self-assembly to create luminescent supramolecular polymers in aqueous media. The luminogens are based on either traditional organic chromophores like anthracene, pyrene etc or aggregation-induced emission (AIE) active chromophores such as cyanostilbene and fumaronitrile. The luminescence of these materials can be tuned by using host-guest chemistry of cucurbiturils. The AIE based materials are also used to create stimuli-responsive solid-state materials.
Photo-responsive Self-assembled Materials
We have employed the cyanostilbene based supramolecular polymers to design photo-responsive materials which exhibit modulation in their emission properties upon irradiation of light. Depending on the choice of amphiphiles and the nature of the assemblies, a variety of photoreactions such as trans-cis isomerization, intramolecular electrocyclization and photo-dimerization can be carried out in a controlled fashion. The photoreactions bring an alteration in the conjugation and geometry which in turn affects the emission wavelength and efficiency.
Small Molecule Luminescent Sensors for Bio-analytes
Small cationic cyanostilbene derivatives have been utilized as sensors for bio-polyanions such as heparin. Heparin is a routinely used anti-coagulant during surgery and we have recently reported a highly efficient ratiometric sensing of heparin in aqueous buffer, human serum and plasma by using the templated assembly of cyanostilbenes on the polyanion surface.
Multivalent Luminescent Receptors
In recent years, self-assembled multivalent receptors, in which smaller and weaker binding sites are non-covalently organized, have been shown to provide high-affinity binding of biologically relevant analytes in competitive media. We have employed the multivalent array of surface-exposed charges on the surface of cationic supramolecular polymers for binding bio-polyanions such as DNA and heparin and also ATP. The binding of these anions leads to a noticeable change in the luminescence properties of the multivalent systems.
Bio-template Based Artificial Light-Harvesting
The co-assemblies of biopolymers such as DNA and heparin with AIE-supramolecular polymers of cyanostilbene derivatives have been explored as efficient light-harvesting systems by incorporating external dyes as the acceptors. The studies are focussed on achieving higher energy transfer efficiency and high amplification in the acceptor dye emission (antenna effect).
