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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modelovanje i analiza fundamentalnih svojstava sumanena / Modeling and analysis of fundamental properties of sumanene

Armaković Stevan 16 October 2014 (has links)
<p>U&nbsp; disertaciji&nbsp; je&nbsp; sprovedeno&nbsp; teorijsko&nbsp; istraživanje&nbsp; fizičko-hemijskih&nbsp; svojstava&nbsp;elektronskog podsistema molekula sumanena. Proračuni su sprovedeni u okvirima DFT i TDDFT&nbsp; teorije&nbsp; sa&nbsp; B3LYP&nbsp; funkcionalom&nbsp; i&nbsp; 6-31Gd,&nbsp; 6-31Gdp i&nbsp; 6-31++Gdp&nbsp; bazisom.&nbsp; Za&nbsp; sve&nbsp;proračune&nbsp; u&nbsp; okvirima&nbsp; navedenog&nbsp; nivoa&nbsp; teorije,&nbsp; kori&scaron;ćen&nbsp; je&nbsp; softverski&nbsp; paket&nbsp; Gaussian03.&nbsp;Ispitana&nbsp; su:&nbsp; strukturna&nbsp; i&nbsp; optička&nbsp; (zajedno&nbsp; sa&nbsp; nelinearnim)&nbsp; svojstva&nbsp; sumanena&nbsp; i&nbsp; njegovih&nbsp;derivata dobijenih modifikovanjem sa atomima bora iazota, aromatična i inverziona svojstva&nbsp;svojstva&nbsp; sumanena&nbsp; i&nbsp; njegovih&nbsp; derivata,&nbsp; adsorpciona&nbsp; svojstva&nbsp; sumanena&nbsp; prema&nbsp; molekulima&nbsp;H<sub>2</sub>, CO, CO<sub>2&nbsp;</sub>i NH<sub>3&nbsp;</sub>i uticaj spolja&scaron;njeg električnog polja na svojstva sumanena.</p><p>Prema&nbsp; dobijenim&nbsp; rezultatima,&nbsp; fundamentalna&nbsp; fizičko-hemijska&nbsp; svojstva&nbsp; molekula&nbsp;<br />sumanena mogu se efikasno i fino pode&scaron;avati supstitucijom i disupstitucijom hetero-atomima&nbsp;bora&nbsp; i&nbsp; azota.&nbsp; Dubina&nbsp; i&nbsp; inverziona&nbsp; barijera&nbsp; sumanena se&nbsp; na&nbsp; ovaj&nbsp; način&nbsp; može&nbsp; menjati&nbsp; u&nbsp; oba&nbsp;smera.&nbsp; Pokazalo&nbsp; se&nbsp; da&nbsp; su&nbsp; ova&nbsp; dva&nbsp; parametra&nbsp; u&nbsp; korelaciji,&nbsp; s&nbsp; obzirom&nbsp; da inverziona&nbsp; barijera&nbsp;skoro potpuno zavisi od dubine sumanena. Slično je i sa aromatičnim svojstvima prstenova,&nbsp;koja se u zavisnosti od broja uvedenih hetero-atomamenja od aromatične preko nearomatične&nbsp;do antiaromatične prirode. Optička svojstva su, pomenutim modifikacijama, takođe značajno&nbsp;pobolj&scaron;ana: apsorpcioni pikovi kod UV/Vis spektra se pomeraju ka vidljivoj oblasti, dok je&nbsp;hiperpolarizibilnost&nbsp; sumanena&nbsp; i&nbsp; derivata&nbsp; sa&nbsp; jednim&nbsp; atomom&nbsp; bora&nbsp; vi&scaron;a&nbsp; od&nbsp; referentnog&nbsp;molekula uree, respektivno, 9 i 49 puta.</p><p>Prema dobijenim rezultatima, adsorpciona svojstva sumanena su veoma kompetitivna&nbsp;sa&nbsp; ostalim&nbsp; organskim&nbsp; molekulima&nbsp; kao&nbsp; &scaron;to&nbsp; su&nbsp; ugljenične&nbsp; nanotube&nbsp; i&nbsp; fuleren&nbsp; C<sub>60</sub>,&nbsp; usled&nbsp;postojanja&nbsp; značajnog&nbsp; dipolnog&nbsp; momenta&nbsp; zbog&nbsp; specifične&nbsp; geometrije.&nbsp; Posebno&nbsp; se&nbsp; ističu&nbsp;pozitivna adsorpciona svojstva prema molekulima H<sub>2&nbsp;</sub><br />i CO. Dok je prvo pomenuti bitan sa&nbsp;energetskog&nbsp; aspekta,&nbsp; specifičnost&nbsp; drugog&nbsp; molekula&nbsp; se&nbsp; ogleda&nbsp; u&nbsp; činjenici&nbsp; da&nbsp; ne&nbsp; može&nbsp; biti&nbsp;adsorbovan od strane ugljeničnih nanotuba.&nbsp;</p><p>Potencijal sumanena, posebno u oblasti organske elektronike, dodatno ističu i rezultati&nbsp;ispitivanja&nbsp; uticaja&nbsp; spolja&scaron;njeg&nbsp; električnog&nbsp; polja.&nbsp; Naime,&nbsp; dobijeni&nbsp; rezultati&nbsp; ukazuju&nbsp; da&nbsp; se&nbsp;specifična&nbsp; (posebno&nbsp; adsorpciona)&nbsp; svojstva&nbsp; sumanena&nbsp; mogu&nbsp; dodatno&nbsp; pobolj&scaron;ati&nbsp; primenom&nbsp;slabog, i eksperimentalno lako ostvarljivog, električnog &nbsp;polja, jer se intenzivira razdvajanje&nbsp;naelektrisanja.</p> / <p>Theoretical&nbsp; investigation&nbsp; of&nbsp; physicochemical&nbsp; properties&nbsp; of&nbsp; electron&nbsp; subsystem&nbsp; of&nbsp;sumanene&nbsp; molecule&nbsp; has&nbsp; been&nbsp; conducted&nbsp; in&nbsp; this&nbsp; doctoral&nbsp; work.&nbsp; Calculations &nbsp;are&nbsp; performed&nbsp;within DFT and TD-DFT with B3LYP functional and 6-31Gd, 6-31Gdp i &nbsp; 6-31++Gdp basis&nbsp;sets. For all calculations, on the mentioned level of theory, Gaussian03software package was&nbsp;used.&nbsp; Investigation&nbsp; encompassed:&nbsp; structural &nbsp; and&nbsp; optical&nbsp; (including&nbsp; nonlinear)&nbsp; properties&nbsp; of&nbsp;sumanene&nbsp; and&nbsp; its&nbsp; derivatives&nbsp; obtained&nbsp; by&nbsp; modification&nbsp; with&nbsp; boron&nbsp; and&nbsp; nitrogen&nbsp; atoms,&nbsp;aromatic and bowl to bowl inversion properties of sumanene and its derivatives, adsorption&nbsp;properties of sumanene towards H<sub>2</sub>, CO, CO<sub>2&nbsp;</sub>i NH<sub>3&nbsp;</sub>molecules and the influence of external&nbsp;electric field to the properties of sumanene.</p><p>According to obtained results, fundamental physicochemical properties of sumanene&nbsp;molecule could be efficiently and finely adjusted with the monosubstitution and disubstitution&nbsp;with&nbsp; hetero-atoms&nbsp; of&nbsp; boron&nbsp; and&nbsp; nitrogen.&nbsp; Bowl&nbsp; depth and&nbsp; bowl&nbsp; to&nbsp; bowl&nbsp; inversion&nbsp; barrier&nbsp;could&nbsp; be&nbsp; tuned&nbsp; in&nbsp; both&nbsp; directions.&nbsp; It&nbsp; was&nbsp; demonstrated&nbsp; that&nbsp; these&nbsp; two&nbsp; parameters&nbsp; are&nbsp;correlated, since bowl to bowl inversion barrier principally depends on the fourth power of&nbsp;bowl&nbsp; depth.&nbsp; Similar&nbsp; situation&nbsp; is&nbsp; with&nbsp; aromatic&nbsp; nature&nbsp; of&nbsp; sumanene&nbsp; rings,&nbsp; which&nbsp; change,&nbsp;depending&nbsp; on&nbsp; the&nbsp; number&nbsp; of&nbsp; introduced&nbsp; boron&nbsp; and&nbsp; nitrogen&nbsp; atoms,&nbsp; from&nbsp; aromatic&nbsp; through&nbsp;non-aromatic&nbsp; towards&nbsp; anti-aromatic&nbsp; nature.&nbsp; Thanks&nbsp; to&nbsp; mentioned&nbsp; modifications,&nbsp; optical&nbsp;properties&nbsp; are&nbsp; improved&nbsp; as&nbsp; well:&nbsp; absorption&nbsp; peaks&nbsp; in&nbsp; UV/Vis&nbsp; spectra&nbsp; shift&nbsp; towards&nbsp; visible&nbsp;area,&nbsp; while&nbsp; hyperpolarizabilities&nbsp; of&nbsp; sumanene&nbsp; and&nbsp; its&nbsp; derivative&nbsp; containing&nbsp; one&nbsp; boron&nbsp; atom&nbsp;are higher than hyperpolarizability of referent molecule of urea, respectively, 9 and 49 times.&nbsp;</p><p>Thanks&nbsp; to&nbsp; significant&nbsp; dipole&nbsp; moment&nbsp; due&nbsp; to&nbsp; the&nbsp; specific&nbsp; geometry, &nbsp;nvestigated &nbsp;adsorption properties of sumanene are very competitive to the other &nbsp;organic molecules such&nbsp;as carbon nanotubes and fullerene C<sub>60</sub>. Positive adsorption properties of sumanene towards H<sub>2&nbsp;</sub>and CO molecules are distinguished. While the H<sub>2&nbsp;</sub>molecule is important from the energetic&nbsp;aspects, specificity of CO molecules is that it can&rsquo;t be adsorbed by carbon nanotubes.</p><p>Potential&nbsp; of&nbsp; sumanene,&nbsp; especially&nbsp; in&nbsp; the&nbsp; field&nbsp; of&nbsp; organic&nbsp; electronics,&nbsp; is &nbsp;emphasized&nbsp;through the obtained results related to the investigation of the influence of external electric&nbsp;field.&nbsp; Obtained&nbsp; results&nbsp; indicate&nbsp; that&nbsp; specific&nbsp; (especially&nbsp; adsorption)&nbsp; properties&nbsp; of&nbsp; sumanene&nbsp;could be additionally improved by application of &nbsp;weak, and experimentally easily achievable,&nbsp;external electric field, due to the higher charge separation.&nbsp;</p>

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