Title Kemijski optički senzori temeljeni na derivatima benzimidazola Title (english) Chemical optical sensors based on benzimidazole derivatives Author Ema Horak Mentor Ivana Steinberg (mentor)Committee member Marijana Hranjec (predsjednik povjerenstva)Committee member Stjepan Milardović (član povjerenstva)Committee member Nikola Basarić (član povjerenstva)Granter University of Zagreb Defense date and country 2017-06-02, Croatia Scientific / art field, NATURAL SCIENCES Universal decimal classificationUDC ) 54 - Chemistry. Crystallography. Mineralogy Abstract Temelj svakog kemijskog senzorskog sustava je receptor, odnosno kemosenzorska molekula sposobna prepoznati potencijalni analit. Optički kemijski senzori za ione kao receptore često primjenjuju konjugirane D-π-A heterocikličke molekulske sustave, koje osim funkcije prepoznavanja analita, osiguravaju i dobra optička svojstva poput snažne apsorpcije pri visokim valnim duljinama i izražene fluorescencije. Na taj način omogućuju jednostavnu i brzu metodu detekcije iona, često uočljivu i golim okom. Jedna od osnovnih gradivnih jedinica mnogih heterocikličkih senzorskih sustava je benzimidazol. Derivati benzimidazola, osim izražene biološke aktivnosti, pronalaze primjenu u tehnologiji lasera, optoelektronici, kao fluorescentne probe i kemosenzori. Benzimidazolna jezgra ugrađena u push-pull molekulski sustav (D-π-A sustav) može biti elektron-donorska jedinica ili dio konjugiranog mosta te znatno utjecati na fotofizička i senzorska svojstva molekule. U ovom radu su istraženi novi heterociklički sustavi za primjenu u senzorima temeljeni na tri klase kromofora: akrilonitrilna benzimidazolna bojila, benzimidazo[1,2-a] kinolinski derivati i Schiffove baze funkcionalizirane benzimidazolnom jezgrom. Karakterizacijom njihovih fotofizičkih, kiselo-baznih i kompleksirajućih svojstava definirani su odnosi strukture i spektralnih svojstava te procijenjena njihova primjenjivost u senzorskim sustavima za pH i metale. Najbolji kandidati imobilizirani u polimerne senzorske matrice, optode, su pokazali vrlo izraženu fluorescenciju (u plavom, žutom i zelenom spektralnom području) i sposobnost reverziblnog praćenja pH vrijednosti u otopinama u fiziološki relevantnom području (pH 5-8). Istraživanjem su otkrivena jedinstvena fotofizička svojstva nekih od ispitivanih derivata benzimidazola, poput emisije uzrokovane nanoagregacijom molekula u vodenim otopinama. Promjenom pH vrijednosti otopine moguće je reverzibilno utjecati na proces stvaranja nanoagregata u otopini i na taj način uključivati i isključivati pojavu emisije pri 600 nm. Otkrivena svojstva mogu pronaći primjenu u senzorima, bio-oslikavanju i funkcionalnim materijalima. Definirane su smjernice za nastavak istraživanja kemosenzorskih mehanizama i materijala, posebno za praćenje interakcija s metalnim ionima i DNA molekulama. Na temelju dobivenih rezultata je zaključeno da benzimidazolna jezgra predstavlja multifunkcionalnu gradivnu jedinicu u optičkim kemijskim senzorima, s dokazanim potencijalom za razvoj novih funkcionalnih (nano)materijala.
Abstract (english) Chemosensing molecules capable of assaying cations or anions in solution (“receptors”) are at the core of every optical chemical sensor. Conjugated D-π-A heterocyclic molecular systems play a dual role in optical chemical ion sensors: as receptors they recognise potential analytes and transform it into analytical signal due to their excellent optical properties, such as strong absorption and fluorescence at long wavelengths. This provides a fast and simple ion detection method, often visible by naked eye. A variety of heterocyclic molecules have been employed in the development of optical sensors in which the benzimidazole unit forms one of the key building blocks. In addition to their recognised biological activity, benzimidazole derivatives also find application in optical lasers and optoelectronics, as fluorescent probes and chemosensors. In recent years, emphasis has been placed on chemosensors that possess push-pull structures (D-π-A systems), where the benzimidazole unit may function as an electron-donating moiety or as a part of a conjugating system. This thesis presents the investigation of three classes of novel benzimidazole functionalised heterocyclic chromophore systems as potential chemosensors: acrylonitriles, benzimidazo[1,2-a]quinolines and Schiff bases. The photophysical, acid-base and metal-ion complexing properties of all derivatives have been identified and their structure-property relationships discussed. Their potential for pH and metal-ion sensing has been evaluated, and the best candidates immobilised in polymer matrices (optodes). The optodes showed very strong fluorescence (in the blue, yellow and green spectral regions) and were able to reversibly monitor pH in solution in the physiologically relevant range (pH 5-8). The research has revealed the ability of some derivatives to form emissive nanoaggregates in aqueous solutions. Aggregation-induced emission (AIE) at 600 nm was found to be pH switchable and reversible, demonstrating great potential for applications in chemosensing, bioimaging and functional materials. Further research in the field of benzimidazole based chromophores and materials, and their potential sensing mechanisms and interactions with metal ions and DNA molecules is proposed. The results of the thesis lead to the conclusion that the benzimidazole unit represents an important multifunctional building block in optical chemical sensors, with proven potential for development of novel functional (nano)materials.
Keywords
senzor
pH
benzimidazol
emisija uzrokovana agregacijom
D-π-A sustav
Keywords (english)
sensor
pH
benzimidazole
aggregation induced emission
D-π-A system
Language croatian URN:NBN urn:nbn:hr:149:886055 Promotion 2017 Project Number: IP-2014-09-3386 Study programme Title: Engineering Chemistry - Doctoral Course Type of resource Text Extent 246 str. ; 30 cm File origin Born digital Access conditions Open access Terms of use Created on 2023-12-06 13:47:09
