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dc.contributor.advisorSebastian, K L
dc.contributor.authorPerumalla, Sravanakumar D
dc.date.accessioned2020-03-26T14:39:33Z
dc.date.available2020-03-26T14:39:33Z
dc.date.submitted2020
dc.identifier.urihttp://etd.iisc.ac.in/handle/2005/4384
dc.description.abstractIt has traditionally been believed that pi-electrons stabilize the D6h structure of benzene. However, this was questioned both using theoretical arguments, as well as circumstantial, experimental evidence. The theoretical arguments have all been based upon the partitioning of the total energy into the sigma- and pi- parts. This partitioning is not unique, the conclusions can be questioned.[1] We suggest an alternative approach based on the forces, calculated using the Hellmann-Feynman theorem. The partitioning of forces into their sigma and pi components is unique and can be used to analyze the behavior of π- and σ- electrons. The procedure is exact and offers a rigorous solution to the problem of pi- distortivity.[2] We have successfully applied the method to benzene and have obtained an unambiguous proof for the pi- distortivity of benzene. Moreover, in all the conjugated and aromatic compounds we considered the pi-electrons are always distortive. We also applied our approach to understand the bent nature of the silicon conjugated compounds. In the second part, I consider the use of nano-porous graphene membranes as gas and isotope filters. Recent experiments demonstrate porous graphene can be used as a molecular sieve.[3] Synthetic chemists are successful to fabricate few nano-porous membranes viz. poly-phenylene, Graphdiyne, C2N-holey sheet. We investigated the separation of Helium and Hydrogen from an atmospheric gas mixture which consists of Helium, Hydrogen, Oxygen, Nitrogen, Carbo-di-oxide, Neon, and Argon using these membranes along with a few other theoretically proposed membranes. Further, we investigated the possibility of these membranes as helium isotope filters. As the quantum effects viz. tunneling, zero-point energy plays a vital role in the separation of the isotopes we did the three dimensional wave packet calculations using an analytical interaction potential. Our calculations showed that maximum He-4/He-3 separation for C2N-holey sheet, C2O-holey sheet, and graphenylene can be achieved around 80K.[4]en_US
dc.language.isoen_USen_US
dc.rightsI grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertationen_US
dc.subjectBenzeneen_US
dc.subjectHückel molecular orbital theoryen_US
dc.subjectGas filtersen_US
dc.subjectNano-porous graphene membranesen_US
dc.subject.classificationResearch Subject Categories::NATURAL SCIENCES::Chemistry::Inorganic chemistry::Coordination chemistryen_US
dc.titleInvestigations on the Pi Distortivity Problem and On the Use of Single Atom Thick Layers as Filtersen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.grantorIndian Institute of Scienceen_US
dc.degree.disciplineFaculty of Scienceen_US


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