PPISR Weekly Seminars: 2016

Abstract: Polyploidy is the heritable condition of possessing more than two complete sets of chromosomes. Polyploids are common among plants, as well as among certain groups of fish, amphibians and recently reported in fungi also. Polyploids arise when a rare mitotic or meiotic catastrophe, such as nondisjunction, causes the formation of gametes that have a complete set of duplicate chromosomes. Diploid gametes are frequently formed in this way. A diploid gamete may fuse with a haploid gamete or with a diploid gamete to form polyploids of different types. Many types of polyploids are found in nature, including tetraploids (four sets of chromosomes), hexaploids (six sets of chromosomes), and other chromosome-pair multiples. In this talk we will discuss the mechanisms underlying polyploidy, and both the advantages and disadvantages of having multiple sets of chromosomes.

Abstract: In the present era, the prime goal for a synthetic chemist is to actively engage in the development of efficient and environmentally benign synthetic protocols in response to the increasing pressure to produce the large number of substances required by society in an environmentally benign fashion. Various stringent regulations and stipulations that are placed on the chemical industries, especially in the area of waste management, have inspired the scientists to explore environmentally benign methods to carry out the reactions in an expeditious manner with minimized waste generation. There are 4 important such routes; Light induced-photochemistry, Microwave-assisted irradiation, Sonochemistry—ultrasonic irradiation, Mechanochemical mixing. Among them, microwave synthesis has gained a lot of importance of late due to shorter synthesis time for organic/ inorganic materials and uniform nanosized synthesis of inorganic materials. This talk will give the overview of these methods with some of case studies.

Abstract: Nature has all the tools and tricks to create repertoire of nano- and micro-structures through the spontaneous self-assembly of highly complicated proteins. Biological molecules that can self-assemble in to a supramolecular structure in an organized way and are genetically tunable, allow us to create biomaterials with a repertoire of structural and functional properties. Although, we are still in the process of understanding the mechanism of protein folding and protein-protein interactions, information on protein structures and their assemblies derived from various techniques is beginning to reveal some of the strategies used by nature. Hence, devising strategies to create biomolecular assemblies is still in the early stages. In this talk, we will be discussing the recent progress in the rational design of nano- and micro-sized architectures utilizing protein scaffolds.

Abstract: Dendrimers are a class of highly branched, multivalent and monodisperse polymers, which have received continuous interest in recent years because of the global demand for new nanomolecules that are useful in advanced technology and medicine. While dendrimers are advantageous for many highly specialized applications, but the high polyvalency of higher-generation dendrimers requires, well-controlled, tailored regioselective chemical engineering. The structural evolution of dendrimers - from simple, monofunctional molecules to the more complex, multifunctional compounds - is inextricably associated with a continuous improvement in traditional synthetic strategies, as well as the development of new synthetic tools. In this seminar, a general introduction to the subject, synthetic stratergies and few applications will be discussed.

Abstract: Crystalline materials maximise understanding of the link between atomic-scale structure and function and facilitates the explanation of macroscopic events on the basis of interactions occurring at the molecular level. Among various classes of porous crystalline materials metalorganic frameworks (MOFs) and covalent organic frameworks (COFs) are in lime light in recent times because of their potential applications in various fields ranging from biology to catalysis. As their names suggest, MOFs are built from the connectivity of organic linker and metal ions/metal clusters, and COFs only from the organic building units. The property that makes these classes of materials distinctly different from others is their "supertunability" i.e., the ability to modulate their properties by modifying the building blocks while maintaining the basic topology. In addition, these materials have the largest reported crystalline pores and surface areas which makes them exciting platforms to explore host-guest chemistry. In this presentation, the details of synthesis and characterization techniques, followed by pore surface guided host-guest chemistry of MOFs and COFs will be discussed. The potential applications of these classes of materials in the areas of gas storage, gas separation, and catalysis will also be presented

Abstract: In recent years much research is focussed on the magnetoelectric effect exhibited by certain materials, where control of electric polarization can be achieved by a magnetic field and magnetization by electric field. This opens up many new applications for devices that can be controlled by voltage. Some examples are magnetic/ferroelectric data storage, magnetocapacitive devices, magnetic sensors and non-volatile memories. Many of these materials have structures that can be tuned by substitution to obtain the desired application. In such materials we could visualize that the electric fields can not only reorient the polarization but also control magnetization at the same time. These properties are interesting for electricfield control of magnetism which is the right route to more energy efficient devices. The physical principles and the state of the art of these concepts will be discussed from both the fundamental materials point of view as well as from the perspective of their application in voltage controlled devices. These materials could potentially be used for information storage and memory applications as they allow the possibility of switching the magnetization with electric field, thus removing the large electric currents required.