Modeling and analysis of fundamental properties of sumanene

Abstract

<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;H₂, CO, CO_2&nbsp;i NH_3&nbsp;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; C₆₀,&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_2&nbsp;<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 H₂, CO, CO_2&nbsp;i NH_3&nbsp;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 C₆₀. Positive adsorption properties of sumanene towards H_2&nbsp;and CO molecules are distinguished. While the H_2&nbsp;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>