Sinteza, struktura i svojstva novih azo boja na bazi 6-hidroksi-4-metil-2-okso-1,2-dihidropiridin-3-karboksamida

Abstract

Heterociklične azo boje sa piridonovim jezgrom predstavljaju značajnu klasu organskih azo boja jer pokazuju visoki molarni ekstinkcioni koeficijent i dobru postojanost na razne vidove obrade. Sintezom 2-piridona sa amidnom grupom u položaju 3, i kuplovanjem dobijenog piridona sa supstituisanim i disupstituisanim diazonijumovim solima dobijene su dvije serije novih azo boja. Struktura novosintetisanih boja na bazi 6-hidroksi-4-metil-2-okso-1,2-dihidropiridin-3- karboksamida je potvrđena elementalnom analizom, FT-IR i NMR spektroskopijom. Termička stabilnost boja je ispitana TG/DTA i DSC metodama, i upoređena sa bojama slične hemijske strukture. Amidna grupa u strukturi sintetisanih boja dovodi do drugačije uređenosti molekula u odnosu na jedinjenja ranije poznate strukture, što je predstavljalo veliki izazov za detaljnu analizu njihove stabilnosti i ponašanja. U ovoj disertaciji je prvi put urađeno detaljno ispitivanje termičke stabilnosti i određivanje kinetičkih i termodinamičkih parametara termički aktiviranih procesa degradacije arilazo piridonskih boja. Tehnološki procesi u kojima se azo boje koriste zahtjevaju povišenu temperaturu pa je termička stabilnost od velikog značaja za implementaciju sintetisanih boja. Nova saznanja o odnosu elektronske strukture i svojstava sintetisanih boja dobijena su ispitivanjem uticaja rastvarača različitih svojstava na apsorpcione i fluorescentne spektre boja. Korelacijom apsorpcionih i fluorescentnih frekvenci izvršena je kvantitativna procjena uticaja dipolarnosti, polarizabilnosti, proton-donorskih i proton-akceptorskih karakteristika rastvarača na položaje apsorpcionih i fluorescentnih maksimuma ispitivanih azo boja. Kvantno-hemijski proračuni su primjenjeni za analizu strukture novosintetisanih boja. DFT metodom je analiziran uticaj supstituenata i rastvarača, promjene u osnovnom i pobuđenom stanju kao i oblik i energije graničnih molekulskih orbitala (HOMO, LUMO i Egap). Poređenje eksperimentalnih i izračunatih vrijednosti strukture i svojstava ispitivanih jedinjenja govori o uspješnosti primjenjenih metoda. Za arilazo piridonske boje je karakteristična i komercijalno značajna azo-hidrazon tautomerija. Snimanjem apsorpcionih i fluorescentnih spektara pri različitim pH vrijednostima i primjenom DFT metode analiziran je uticaj prirode i položaja supstituenata u arilazo komponenti, kao i uticaj rastvarača na položaj azo-hidrazon ravnoteže kod ovih boja. Filmovi na bazi poli(vinil-alkohola) i arilazo piridonskih boja su sintetisani u cilju dobijanja novih dozimetrijskih sistema za detekciju gama zračenja. Dobijeni filmovi su ozračeni različitim dozama gama zračenja Co60 u INNV, a promjene do kojih je došlo nakon izlaganja γ-zracima praćene su spektrofotometrijski snimanjem refleksionih spektara ozračenih i neozračenih filmova, kao i FTIR analizom. Prednost polimernih obojenih filmova u odnosu na komercijalno poznate dozimetre je vizuelno uočavanje promjene boje nakon izlaganja γ-zracima što ih čini jednostavnim za upotrebu. Promjene boje mogu se objasniti raskidanjem glavnog lanca polimera, nastajanjem slobodnih radikala i njihovim reakcijama sa molekulom boje.

Heterocyclic azo dyes with a pyridone moiety represent a significant class of organic azo dyes because of its high molar extinction coefficient and good resistance to various types of processing. Synthesis of 2-pyridone with the amide group in position 3, and coupling of the obtained pyridone with substituted and disubstituted diazonium salts gave two series of new azo dyes. The structure of newly synthesized dyes based on 6-hydroxy-4-methyl-2-oxo-1,2- dihydropyridine-3-carboxamide was confirmed by elemental analysis, FT-IR and NMR spectroscopy. The thermal stability of the dyes was performed by TG/DTA and DSC methods and compared with dyes of similar chemical structure. The amide group in the structure of the synthesized dyes leads to a different arrangement of the molecules in relation to the compounds of the previously known structure, which posed a great challenge for a detailed analysis of their stability and behavior. In this dissertation, for the first time, a detailed examination of thermal stability and determination of kinetic and thermodynamic parameters of thermally activated degradation processes of arylazo pyridone dyes was performed. Technological processes in which azo dyes are used require elevated temperature, so thermal stability is of great importance for the implementation of synthesized dyes. New knowledge about the relationship between the electronic structure and the properties of synthesized dyes was obtained by examining the influence of solvents of different properties on the absorption and fluorescent spectra of dyes. By correlating the absorption and fluorescent frequencies, a quantitative assessment of the influence of dipolarity, polarizability, proton-donor and proton-acceptor characteristics of the solvent on the positions of absorption and fluorescent maxima of the investigated azo dyes was performed. Quantum chemical calculations were applied to analyze the structure of newly synthesized dyes. The influence of substituents and solvents, changes in the ground and the excited state, as well as the shape and energy of boundary molecular orbitals (HOMO, LUMO i Egap), were analyzed by the DFT method. A comparison of experimental and calculated values of the structure and properties of the tested compounds indicates the success of the applied methods. Arylazo pyridone dye is characterized by commercially significant azo-hydrazone tautomerism. The influence of the nature and position of the substituents in the arylazo component, as well as the influence of solvent properties on the position of the azo-hydrazone equilibrium in these dyes were analyzed by recording the absorption and fluorescence spectra at different pH values and applying the DFT method. Films based on poly(vinyl alcohol) and arylazo pyridone dyes were synthesized in order to obtain new dosimetric systems for gamma radiation detection. The obtained films were irradiated with different doses of gamma radiation Co60 in INNV, and the changes that occurred after exposure to γ-rays were monitored spectrophotometrically by recording the reflection spectra of irradiated and non-irradiated films, as well as FT-IR analysis. The advantage of polymer colored films over commercially known dosimeters is the visual detection of color change after exposure to γ-rays which makes them easy to use. The color changes can be explained by the breaking of the main polymer chain, the formation of free radicals and their reactions with the dye molecule.