Studies on the self-assembly of some heterocycle containing star-shaped and polycatenar mesogens

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Liquid crystals (LCs) are unique functional soft materials combining both order and mobility on molecular, supramolecular and macroscopic levels. The shape anisotropic molecules which exhibit this unique behavior are also known as mesogens. They can be organic (forming thermotropic and lyotropic phases), inorganic (metal oxides forming lyotropic phases) or organometallic (metallomesogens) in nature. Conventionally, the anisometric molecules employed to stabilize thermotropic LC phases are either rod-like (calamitic) or disc-like (discotic). Calamitics form the backbone of the well-established flat panel display industry. Discotic LCs also have made notable progress in recent years, both from scientific and application viewpoints and slowly they are finding a foothold in the main stream of organic electronics. It is also known that LC behavior is realizable with molecules differing in their shape from conventional LCs. The general feature of majority of such materials is the molecular structural contrast with in the molecule i.e., these molecules are made up of chemically different molecular parts that are incompatible with each other. Some of the important examples of non-conventional systems are oligomers, polycatenars, bent-core molecules, polyhydroxy amphiphiles, octahedral complexes, star-shaped molecules, rod-coil molecules and dendrimers. In the case of non-conventional LCs, the main driving force for the self-assembly of these molecules to form liquid-crystalline (LC) phases is based on the nano-segregation of chemically or physically different building blocks and the tendency to efficiently fill the space in condensed state.
Supervisor: A. S. Achalkumar