Fluorescencija čvrstog stanja heteroaromatskih kromofora u funkcionalnim materijalima

master's thesis

• Title (english): Solid-state fluorescence of heteroaromatic chromophores for use in functional materials
• Author: Aleksandra Šimanović
• Mentor: Ivana Steinberg (mentor)
• Committee member: Ivana Steinberg (predsjednik povjerenstva)
• Committee member: Nataša Perin (član povjerenstva)
• Committee member: Ema Horak (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-07-04, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry; Applied Chemistry

Abstract

U ovom radu je karakterizirano pet derivata benzimidazola s ciljem razvoja novih funkcionalnih materijala: 2-[(4-N,N-dimetilamino)benz-2-ilidenamino]-5(6)-cijanobenzimidazol (1), 2-[(4-N,N-dimetilamino)benz-2-ilidenamino]-5(6)-nitrobenzimidazol (2), 2-[(4-N,N-dietilamino-2-hidroksi)benz-2-ilidenamino]-5(6)-cijanobenzimidazol (3), 2-[(4-N,N-dietilamino-2-hidroksi)benz-2-ilidenamino]-5(6)-nitrobenzimidazol (4) i E-2-(2-benzimidazolil)-3-(4-N,N-dimetilaminofenil)akrilonitril (5). Spojevi su dizajnirani kao D-π-A kromofori s elektron donorskim N,N-dimetil ili N,N-dietil amino skupinama i jakim elektron akceptorskim skupinama -NO2 ili -CN. Fotofizička svojstva spojeva 1-5 ispitana su UV-vidljivom apsorpcijskom i fluorescencijskom spektroskopijom u različitim otapalima, prilikom čega je uočeno stvaranje nanoagregata u vodi i stvaranje novog fluorescencijskog maskimuma pri višim valnim duljinama. Navedena pojava se može opisati kao emisija izazvana agregacijom (engl. Aggregation induced emission, AIE) te upravo ona pruža brojne potencijalne primjene. Fluorofori u čvrstom stanju (engl. solid-state fluorophores) temeljeni na AIE su jedan od široko primjenjivanih primjera funkcionalnih materijala. Iako su vrlo slabo fluorescentni u otopini, spojevi 1-5 pokazuju intenzivnu fluorescenciju u čvrstom stanju. Spektrofotometrijskim metodama je karakterizirana fluorescencija 1-5 u čvrstom stanju te je ispitan utjecaj vanjskih čimbenika na emisiju čvrstog stanja. Emisija spojeva 1-5 uočava se u širokom dijelu elektromagnetskog spektra te golim okom uočavamo fluorescenciju od žute do crvene boje. Crvena emisija spoja 4 je osobito atraktivna jer su crveni fluorofori u čvrstom stanju vrlo rijetki. Većina spojeva pokazuje djelomičnu promjenu fluorescencijskih karakteristika prilikom utjecaja vanjske mehaničke sile. Najizraženija promjena u fluorescencijskim karakteristikama se uočava za spoj 4 (Δλ = 36 nm) te ga možemo okarakterizirati kao reverzibilni mehanokromatski materijal. Spoj 4 je također pokazao najveću osjetljivost na mikrookolinu (atmosferu zasićenu parama organskih otapala) prilikom čega se uočava pad intenziteta fluorescencije s porastom polarnosti otapala.

Abstract (english)

In this work five benzimidazole derivatives were characterised to develop novel functional materials: 2-[(4-N,N-dimethylamino)benz-2-ylideneamino]-5(6)-cyanobenzimidazole (1), 2-[(4-N,N-dimethylamino)benz-2-ylideneamino]-5(6)-nitrobenzimidazole (2), 2-[(4-N,N-diethylamino-2-hydroxy)benz-2-ylideneamino]-5(6)-cyanobenzimidazole (3), 2-[(4-N,N-diethyamino-2-hydroxy)benz-2-ylideneamino]-5(6)-nitrobenzimidazole and E-2-(2-Benzimidazolyl)-3-(4-N,N-dimethylaminophenyl)acrylonitrile (5). Compounds are designed as D-π-A chromophores with electron-donating N,N-dimethyl or N,N-diethyl amino group and strong electron-withdrawing -NO2 and –CN groups. The photophysical properties of compounds 1-5 were investigated by UV-visible absorption and fluorescence spectroscopy in various solvents; the formation of nanoaggregates in water and the creation of a new emission maximum at higher wavelengths was observed. This phenomenon can be described as aggregation induced emission (AIE) and it provides numerous potential applications. Solid-state fluorophores based on AIE are examples of widely used functional materials. Although poorly fluorescent in solution, compounds 1-5 show intense fluorescence in solid-state. Fluorescence of compounds 1-5 was characterised using spectrophotometric methods and the influence of external factors on solid-state was studied. The emission of compounds 1-5 is observed in a wide part of the electromagnetic spectrum and fluorescence from yellow to red is observed by naked eye. The red emission of compound 4 is particularly attractive because the red fluorophores in solid-state are very rare. Most of the compounds show a partial change in the emission characteristics when the external mechanical force is applied. The biggest change in emission characteristics is observed for compound 4 (Δλ = 36 nm) and it can be characterised as a reversible mechanochromic material. Compound 4 also exhibited the highest sensitivity to the microenvironment (a saturated atmosphere of organic solvents) showing a decrease in the fluorescence intensity with the increase of solvent polarity.

• Keywords: Schiffove baze; benzimidazol; fluorescencija čvrstog stanja; AIE; mehanokromizam
• Keywords (english): Schiff bases; benzimidazole; solid-state fluorescence; AIE; mechanochromism
• Language: croatian
• URN:NBN: urn:nbn:hr:149:093227
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Applied organic chemistry; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-05-08 09:50:38