Azulenoaren propietate optikoen azterketa teorikoa

Abstract

[EU]Azulenoa propietate fotofisiko bereziak azaltzen dituen konposatua da. Bere isomeroa den Naftaleno molekularekin konparatuz gero propietate oso desberdinak ditu, hala nola, intentsitate handiko kolore urdina, momentu dipolar nahiko handia, eta ez-ohiko fluoreszentzia. Propietate hauetaz gain Azulenoak Singlet-Fission (fotoi bat absorbatu eta bi emititu) bezalako prozesu fotokimiko berezietan parte har dezakeela uste da, eta ondorioz sistema molekular interesgarria da, aplikazio ugari izan ditzakeelarik (eguzki-zeluletan adibidez). Lan hau bi zatitan banatu da. Lehenengoan Azulenoaren oinarrizko egoera elektronikoa eta lehen bi egoera kitzikatuak aztertu dira. Erreferentziazko datuetan oinarrituz, C2v simetriako azuleno monomeroaren optimizazioa egin da, eta bere oinarrizko egoera elektronikoaren orekazko geometria kalkulatu da. Ondoren, azuleno monomeroaren oinarrizko eta lehen bi egoera elektroniko kitzikatuak aztertu dira. Lanaren bigarren zatia Azuleno kristalen modelizazioan oinarritu da. Azulenoak kristal ezordenatuak eratzen ditu, baina orokorrean bi dimero nagusi ageri dira, C2h simetriaduna eta dimero koplanarra. Lan honetan, bi dimeroen kasuan dagoen elkarrekintza aztertu da, elkarrekintza geometriak eta energiak lortuz, eta kristaletan ezagunak diren geometriekin alderatuz. Azuleno kristaletan ematen diren konformazioekin jarraituz, beraien egoera elektroniko kitzikatuak aztertu dira oinarrizko egoerarekin alderatuz. Dimeroen kasuan, bi modelo ideal eraiki dira dimerizazioa aztertzeko. Honela, dimerizazio energia 4 kcal/mol ingurukoa dela kalkulatu da, elkarrekintza hau ahula izanik. Dimerizazio kurbak kalkulatu dira ere propietateak distantziarekin nola aldatzen diren ikusteko. Elkarrekintza ahula izanik, monomeroen propietateak ez dira asko aldatzen dimerizazioan.

Euskera

[EN]Azulene is an organic compound with interesting photophysical properties. Compared with its isomer Naphthalene, Azulene presents special properties such as an intense blue color, a large dipole moment and a uncommon fluorescence. In addition to those properties it is believed that Azulene might participate in single-fission processes (absorption of a photon and emission of two photons) being a system of great interest for its posible aplications (for example in solar cells). This work is divided into two different parts. In the first part we have analyzed the ground state and two first excited states. Based on reference data, the optimization of C2v Azulene monomer has been carried out. After that, its first two electronic excited states have been analyzed. The second part of the work is based on the modeling of Azulene crystals. Azulene forms disordered crystals but, in general, there are two types of dimer; a C2h dimer and a coplanar one. In this work, we analyze the interaction that exists in both of them, obtaining ground state geometries and energies, and comparing with reference geometries. Continuing with these conformations, their excited states have also been studied and compared with the ground state. For both dimers, two ideal models have been simulated to analyze dimerization. It has been calculated that the interaction energy it is around 4kcal/mol, clearly being a weak interaction. Another objective of the dimerization curves is to see the change in properties depending on distance. Since the interaction is weak, the properties of monomers change very little with dimerization.

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