Dr. Sourav Saha

Advancement of chemical and biological sciences as well as advent of bio- and nanotechnology have created a demand for materials that can bridge the gap between scientific knowledge and technological applications. While organic chemistry provides tools for making molecules with unique properties that can be modulated on-demand, supramolecular chemistry and molecular self-assembly, based on noncovalent interactions between components, offer the scope of extending the range of molecular dimension to nanometer scale. Research in our group will focus on employing organic synthesis and molecular self-assembly as tools for developing functional nanomaterials to tackle challenges in the fields of renewable energy, bioengineering, and nanotechnology.

Light-Harvesting Supramolecular Materials for Solar Energy Conversion
The aim of this project is to construct light-harvesting supramolecular materials for solar to electrical energy conversion, by assembling electro- and photoactive organic building blocks via dynamic, yet robust, noncovalent bonding interactions. In the presence of sunlight, self-assembled light-harvesting materials undergo vectorial electron transfer process, involving a chromophore and a series of electron carriers to produce charge-separated states. Thus, solar energy is converted to electrochemical potentials, which become the driving force for photocurrent generation. Because of the dynamic nature of molecular self-assembly, these materials may be self-repairable and recyclable, making them useful for applications in organic solar cells.

Self-Assembled Molecular Tweezers and ∞-Shaped Foldamers for Ion-Pair Recognition
The goal of this project is to develop synthetic ion-pair recognition channels (I) by alternately self-assembling two types of molecular tweezers, one designed to bind anions and the other designed to bind cations inside their polar cavities and (II) by constructing unimolecular ∞-shaped double-helical foldamers that will present alternating helices with opposite chiralities and cavities with opposite polarities, programmed to bind anions inside one channel and cations inside the other channel. Synthetic ion-pair channels, spanning across phospholipid bilayer membranes, will have the potential to co-transport salts across cell membranes under concentration and potential gradients. They may be useful for treatment of diseases caused by malfunction of natural ion-channels, like cystic fibrosis. Higher order folded structures and ion-pair binding properties of the artificial channels will be thoroughly investigated.

Electroluminescent Bistable [2]Rotaxanes for Organic Light-Emitting Devices
The objective of this project is to develop electroluminescent bistable [2]rotaxanes by installing a hole-injecting group on the ring component, which will remain interlocked with the dumbbell component carrying an electron-injecting luminescent group. When holes and electrons recombine inside the luminescent unit, light will be emitted from the resulting excitons. Mechanical switching of [2]rotaxanes may not be required for light emission. The color of the emitted light can be tuned from red to green to blue (RGB) by grafting different luminescent groups onto the dumbbell component. These [2]rotaxanes may be employed in organic light-emitting devices as luminescent materials, which should display an improved luminescence and power efficiency as a result of balanced charges in each of the single molecule devices.