Three series of some novel arylazo pyridone dyes,
5-arylazo-6-hydroxy-4-phenyl- 3-cyano-2-pyridone dyes,
5-arylazo-6-hydroxy-4-(4-metoxyphenyl)-3-cyano-2-pyridone dyes and
...5-arylazo-6-hydroxy-4-(4-nitrophenyl)-3-cyano-2-pyridone dyes have been
synthetized. The structure of the dyes was confirmed by UV-Vis, FTIR, 1H NMR
and 13C NMR spectroscopy and elemental analysis. The solvatochromic behavior
of the dyes was evaluated with respect to their visible absorption properties
in various solvents. The azo-hydrazone tautomeric equilibration was found to
depend on the substituents as well as on the solvent. These dyes exist in the
hydrazone form in the solid state and in solvent DMSO-d6 and there was an
equilibrium between hydrazone form and azo form in the different solvents.
The Kamlet-Taft and Catalan parameters were used for describing the
solutesolvent interactions and solvatochromic shifts of the visible
absorption band. It was found that the solute dipolarity / polarizability
(especially polarizability by Catalan equation) play an important role in the
description of the pronounced solvatochromism in the studied solutions. The
Catalan solvent scales were found to be more suitable for describing the
solvatochromic shifts. The geometry data of the investigated dyes were
obtained using DFT quantumchemical calculations. The obtained calculational
results are in very good agreement with the experimental data.
U okviru proučavanja strukture i karakteristika azo piridonskih boja, u
čvrstom stanju i u rastvoru, su sintetisane tri nove serije arilazo
piridonskih boja koje do sada nisu poznate u literaturi:
5-arilazo-6-hidroksi-4-fenil-6-cijano-2-piridonske boje, 5-arilazo-6-
hidroksi-4-(4-metoksifenil)-6-cijano-2-piridonske boje i
5-arilazo-6-hidroksi-4-(4- nitrofenil)-6-cijano-2-piridonske boje. Sve azo
boje su sintetisane diazotovanjem odgovarajućih 4-supstituisanih anilina i
kuplovanjem dobijenih diazo soli sa odgovarajućim piridonima, prethodno
dobijenim iz odgovarajućih etil-4-supstituisanih benzoilacetata i
cijanoacetamida. Struktura sintetisanih azo boja je potrvđena na osnovu
podataka iz UV-vis, FTIR, 1H NMR i 13C NMR spektara. Solvatohromna svojstva
su određena u odnosu na njihovu apsorpciju u vidljivom delu UV-Vis spektra u
različitim rastvaračima. Efekti polarnosti rastvarača, proton-donorske i
proton-akceptorske karakteristike interakcije rastvarač-rastvorena supstanca
su kvantitativno procenjene Kamlet-Taft-ovim i Catalan-ovim solvatohromnim
modelima. Proučavanje uticaja supstituenata na arilazo komponenti na
azo-hidrazon tautomeriju sintetisanih boja izvršeno je korelacijom UV-Vis
apsorpcionih frekvenci Hammett-ovom jednačinom. Azo boje sintetizovane u ovoj
disertaciji mogu postojati u azo i hidrazon tautomernim oblicima. Na
azo-hidrazon ravnotežu veliki uticaj imaju rastvarači i supstituenti prisutni
u arilazo komponenti. Rezultati ostvareni u ovom radu ukazuju na dominantan
hidrazonski tautomerni oblik, kako u čvrstom stanju tako i u rastvorima azo
boja u ratsvaračima različitih svojstava. Hidrazonska struktura proučavanih
azo boja je potvrđena kvantno-hemijskim izračunavanjima korištenjem DFT/B3LYP
metode.
In this dissertation photocatalytic degradation of 5-(4-substituted phenylazo)-6- hydroxy-4-methyl-3-cyano-2-pyridone using simulated sun light was investigated. The commercial TiO2, Aeroxide P25 and ...immobilized films were used as photocatalysts. The first part of the dissertation describes synthesis and characterization of arylazo pyridone dyes. The arylazo pyridone dyes having different substituents (from electron-donating to electon-withdrawing) on phenyl ring of diazo component were synthesized by two ways. The first synthesis way includes diazotization-coupling reactions and involves the conversion of 4-sulphoaniline to the diazonium ion intermediate 4-sulphobenzendiazonium ion, followed by the reaction with 3-cyano-6- hydroxy-4-methyl-2-pyridone. In the second way, the dyes were synthesized by coupling diazonium salts with ketoesters followed by condensation with cyanoacetamide. The influence of electronic effects of substituents group in the arylazo component on the absorption spectra, azo/hydrazo tautomerism and acid constants of dyes was investigated and quantified using Hammett equation (principle of linear free energy relationship-LFER). The obtained results showed that electron-withdrawing substituents in the arylazo component increase π,π-conjugation in hydrazo tautomer, while electron-donating substituents increase π,π-conjugation in azo tautomer. In addition, it was observed that the electronic behaviour of the nitrogen atoms of azo and hydrazo group is different between derivates with electron-donating and electron-withdrawing substituents. The results also showed that the quantity of hydrazo component and pKa values increased with increasing electron-donating and electron-withdrawing efects of substituents. In the second part of the dissertation the photocatalytic degradation of synthesized dyes using commercial TiO2 Aeroxide P25 was investigated. The influence of different process parameters (catalyst concentration, initial dye concentration, temperature, pH, H2O2 concentration, ethanol concentration) on photodegradation rate of 5-(4-sulpho phenylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridone was studied. The reaction kinetics analysis showed that photodegradation exhibits pseudo first-order kinetics according to Langmuir-Hinshelwood model. The results from TOC analysis showed that dye is efficiently mineralized using investigated photocatalytic process. In addition, the effect of substituents in the diazo component of the dyes on their photocatalytic degradation was studied and quantified using Hammett equation. The results indicated that the photodegradation rates were in a good degree dependent on the substituent electronic effects being accelerated by electron-withdrawing groups and retarded by electrondonating groups. The third part of the dissertation describes the photocatalytic degradation of 5-(4- sulphophenylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridone using porous TiO2 films. TiO2 films were prepared on stainless steel substrate by spray pyrolysis technique. Two groups of films were synthesized: first from hydrothermally prepared colloidal TiO2 solution and second group using TiO2 Aeroxide P25 suspension. The prepared films were annealed at different temperatures and characterized using following methods: (1) X-ray diffraction analysis (XRD) (2) Hg-porosimetry and N2-physisorption (3) Scanning electron microscopy (SEM) (4) Photo-electron spectroscopy (XPS) (5) UVVisible Diffuse Reflectance spectroscopy (DR UV/Vis). The obtained results showed that films annealed at different temperature had different structural, textural and morphological properties. The results from photocatalytic tests showed that photoactivity of the films decreased with increasing anenealing temperature, due to alterations in the films properties. Comparation of photoactivity of films with different thickness showed that, due to limitations imposed by light transport and dye diffusion, the inner parts of films are less active than outer parts. These difusion limitations depends on textural properties of films. In addition, the photoactivity of TiO2 powder Aeroxide P25 and corresponding film was compared. The difference in photoactivity arises not only from diffusion limitations in films, but also from the presence of different metals in film layer.
U ovom radu proučavana je fotokatalitička degradacija arilazo piridonskih boja, 5-(4- supstituisani fenilazo)-6-hidroksi-4-metil-3-cijano-2-piridona, korišćenjem simulirane sunčeve svetlosti. Kao katalizatori korišćeni su komercijalni TiO2 (Aeroxide P25) i TiO2 filmovi. U prvom delu rada opisana je sinteza i karakterizacija arilazo piridonskih boja. Arilazo boje su sintetisane na dva načina. Prvi način sinteze obuhvata reakcije diazotovanja supstituisanih anilina i kuplovanja dobijene diazonijum soli sa 6-hidroksi- 4-metil-3-cijano-2-piridonom. Drugim načinom arilazo piridonske boje su dobijene kuplovanjem diazonijum soli sa ketoestrom uz ciklizaciju nastalog proizvoda etil 3- okso-2-(supstitisanifenildiazenil)butanoata sa cijanoacetamidom. Da bi se ispitao uticaj elektronskih efekata supstituenata na apsorpcione spektre sintetisanih boja, azo-hidrazo tautomeriju i konstante kiselosti, sintetisano je jedanaest boja koje su se razlikovale po prirodi supstituenta na fenilnom jezgru diazo komponente. Ovi uticaji su kvantifikovani korišćenjem Hammett-ove jednačine (princip linearnih korelacija slobodnih energija - LFER princip). Dobijeni rezultati su pokazali da elektron-akceptori prisutni na fenilom jezgru utiču na povećanje π,π-konjugacije u hidrazo tautomeru, dok elektron-donori utiču na povećanje π,π-konjugacije u azo tautomeru. Pokazano je da je elektronsko ponašanje atoma azota azo i hidrazo grupe različito kod boja sa elektron-donorskim i elektronakceptorskim supstituentima. Takođe, dobijeni rezultati su pokazali da je udeo hidrazo komponente i konstanta kiselosti najmanji kod nesupstituisanih boja, dok sa povećanjem elektron-donorskih i elektron-akceptorskih svojstava supstituenata u diazo komponenti boja ove vrednosti rastu. U drugom delu rada proučavana je fotokatalitička degradacija arilazo piridonskih boja korišćenjem komercijalnog katalizatora TiO2, Aeroxide P25. Ispitivan je uticaj sledećih reakcionih parametara na brzinu fotodegradacije 5-(4-sulfofenilazo)-6-hidroksi-4-metil- 3-cijano-2-piridona: količina katalizatora, početna koncentracija boje, temperatura, pH, koncentracija H2O2, prisustvo etanola. Pokazano je da reakcije fotodegradacije slede kinetiku pseudo prvog reda, prema Langmuir-Hinselwood-ovom modelu. Rezultati TOC analize su pokazali da se boja može uspešno demineralizovati ispitivanim fotokatalitičkim procesom. U ovom delu rada proučavan je i uticaj elektronskih svojstava suspstituenata na fenilnom jezgru supstituisanih boja na brzine fotodegradacije. Brzine fotodegradacije su korelisane sa Hammett-ovim konstantama supstituenata. Najveće brzine degradacije su dobijene kod boja sa elektronakceptorskim supstituentima, dok su najmanje brzine degradacije dobijene kod boja sa elektron-donorskim supstituentima. U trećem delu rada proučavana je fotodegradacija arilazo boje, 5-(4-sulfofenilazo)-6- hidroksi-4-metil-3-cijano-2-piridona korišćenjem poroznih TiO2 filmova. TiO2 filmovi su sintetisani na nosaču od nerđajućeg čelika metodom sprej pirolize. Pripremljene su dve grupe filmova: prva grupa polazeći od koloidnog TiO2 rastvora dobijenog hidrotermalnim postupkom i druga grupa polazeći od suspenzije TiO2, Aeroxide P25. Dobijeni filmovi su žareni na različitim temperaturama, a potom okarakterisani primenom sledećih metoda: (1) rendgenostrukturna analiza (XRD), (2) Hgporozimetrija i N2-fizisorpcija, (3) skenirajuća elektronska mikroskopija (SEM), (4) foto-elektronska spektroskopija X-zracima (XPS), (5) difuziono-refleksiona spektroskopija ultravioletne i vidljive oblasti (DR UV/Vis). Dobijeni rezultati su pokazali da strukturna, morfološka i teksturalna svojstva filmova zavise u velikoj meri od temperature žarenja. Rezultati fotokatalitičkih testova su pokazali da se fotoaktivnost filmova smanjuje sa povećanjem temperature žarenja, usled promena u njihovim svojstvima. Poređenjem fotoaktivnosti filmova različitih debljina zaključeno je da su usled difuzionih ograničenja boje i/ili slabijeg prodiranja svetlosti, donji delovi filma manje aktivni nego gornji. Pokazano je da difuzija boje i svetlosti zavisi od teksturalnih svojstava filmova. U radu je izvršeno i poređenje fotoaktivnosti Aeroxide P25 TiO2 praha, i filma dobijenog iz suspenzije TiO2, Aeroxide P25. Dobijeni rezultati su pokazali da je fotoaktivnost filmova značajno manja u odnosu na fotoaktivnost ogovarajućih prahova ne samo usled difuzionih ograničenja u sloju filma, već najverovatnije i usled prisustva metala iz nosača.
