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Sinteza in vrednotenje novih fluoroforov iz skupine polimetinov in kumarinov
Janežič, Valerija (Avtor), Pajk, Stane (Mentor) Več o mentorju... Povezava se odpre v novem oknu

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Izvleček
Pojav fluorescence so z namenom preverjanja originalnosti lesa, na osnovi obarvanja njegovega ekstrakta, izkoriščali že pred pol tisočletja. Skozi čas so se na tem področju izoblikovale razlage pojava, odkrivali novi načini uporabe in sintetizirali številni fluorofori. Pojav fluorescence sedaj izkoriščajo mnoge metode iz področij fizike, biologije, kemije in medicine. Tako smo priča številnim novim tehnikam, a razvoj novih fluoroforov in fluorescentnih sond zaostaja. V magistrski nalogi Andraža Bevka je opisan nov fluorofor iz skupine polimetinov. Reakcijske pogoje do opisanega fluorofora je v svoji magistrski nalogi raziskala Nataša Vek, v okviru naše magistrske naloge pa smo preučili kakšen tip reaktantov reagira pod pogoji sinteze. Med drugim smo pri reaktantih zamenjali nitril z estrsko skupino. Reakcija v tem primeru poteče, a do drugačnega fluorofora. Poleg tega smo ugotovili, da je za potek reakcije pri reaktantu nujno potreben aromatski dušik piridinskega tipa. Določili smo tudi izkoristke treh reakcij s pomočjo tekočinske kromatografije visoke ločljivosti (HPLC). Pri fluorescenci prihaja do emisije fotonov po predhodni absorpciji le-teh. Poleg eno-fotonske, so molekule zmožne tudi dvo-fotonske absorpcije. Teorija dvo-fotonske absorpcije, ki je bila razvita v tridesetih letih prejšnjega stoletja, se je v dobri sredini 20. stoletja z izumom dovolj močnih laserjev razvila v prakso. Ker ima metoda dvo-fotonske fluorescentne mikroskopije številne prednosti pred eno-fotonsko, so se takrat začele tudi raziskave v smeri sinteze molekul s sposobnostjo dvo-fotonske absorpcije, ki so stabilne in imajo visok kvantni izkoristek. V sklopu tega so ugotovili določene parametre, ki jih je pri načrtovanju dvo-fotonskih sond potrebno upoštevati. V magistrski nalogi smo sintetizirali v literaturi že opisano dvo-fotonsko sondo imenovano pajkovec in dvo-fotonsko sondo, ki jo uvrščamo med kumarine. Pri zadnji smo naleteli na številne težave pri sintezi, tako da vseh želenih spojin nismo uspeli pripravit. S sintetiziranimi dvo-fotonskimi sondami smo označili ogljikove nanocevke, žal pa po vezavi na nanocevke kolegi z Instituta Jožef Stefan (IJS) niso zaznali signala na fluorescenčnem mikroskopu. Najverjetneje, ker ogljikove nanocevke dušijo fluorescenco. Vsem pripravljenim sondam smo pomerili ekscitacijski in emisijski spekter. Spektra spojine 1 ustrezata opisanim spektrom v literaturi. Spojina 7 izstopa po relativno velikem Skokesovem premiku. Spojina 19 pa izkazuje izrazit premik ekscitacijskega in emisijskega spektra k nižjim valovnim dolžinam glede na sorodno spojino 17.

Jezik:Slovenski jezik
Ključne besede:fluorofori, dvo-fotonske sonde, derivati kumarina, polimetini
Vrsta gradiva:Magistrsko delo/naloga (mb22)
Organizacija:FFA - Fakulteta za farmacijo
Leto izida:2019
Število ogledov:476
Število prenosov:163
Metapodatki:XML RDF-CHPDL DC-XML DC-RDF
 
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Sekundarni jezik

Jezik:Angleški jezik
Naslov:Synthesis and characterisation of novel fluorophores from polymethyne and coumarin groups
Izvleček:
The phenomenon of fluorescence was already used half a millennium ago for the purpose of determining the originality of the wood, based on the colouring of its extract. In the last two centuries, explanations of the phenomenon have been developed, new methods of use have been discovered and many fluorophores have been synthesized. Methods based on fluorescence have become invaluable in the fields of physics, biology, chemistry and medicine. And new techniques are continuously being introduced while the development of new fluorophores is lagging behind. Recently, a new fluorophore from polymethine family has been described in master's thesis of Andraž Bevk. Synthesis was subsequently optimized by Nataša Vek, described in detail in her master's thesis. In our master's thesis we investigated the nature of reactants that react under optimised conditions. Several different arylacetonitrils and ethyl arylacetates were tested. According to our results heteroaryl moiety must contain pyridine-like nitrogen, while the products of ethyl arylacetates undergo further cyclisation. Additionally, we determined the yields of three reactions with developed high performance liquid chromatography (HPLC) method. Fluorophore emits photons after prior absorption. In addition to single-photon, the molecules are also capable of two-photon absorption. The theory of two-photon absorption was developed in the 1930s, but came into practice in the middle of the 20th century with the invention of strong enough lasers. Since the method of two-photon fluorescence microscopy has many advantages over the one-photon, the middle of the 20th century was also a time, when specialized two-photon probes were being first developed and studied. In the master's thesis we prepared a two-photon probe already described in the literature, and new coumarin-based two-photon probes. We encountered some problems during the synthesis of the latter and we were not able to prepare all the desired derivatives. CNT were labelled with synthesized two-photon probes, however colleagues at Institut Jožef Stefan (IJS) were not able to detect any signal, probably because of the quenching of fluorescence by CNT. Additionally, the excitation and emission spectra of synthesized fluorophores were recorded. Spectra of probe 1 are in accordance with the ones reported in the literature. Probe 7 stands out because of relatively large Stokes shift. And surprisingly, fluorophore 19 has significant blue-shift compared to the similar fluorophore 17.

Ključne besede:fluorophores, two-photon probes, coumarin derivates, polymethines

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