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Azo dyes are known as structurally diverse class of organic compounds bearing one or more azo groups (–N=N–) as a bridge between organic residues of which at least one is an aromatic moiety. This group of synthetic dyes is obtained easily by the reaction of diazo coupling with high yield. The importance of azo dyes is reflected in the fact that they account for 60 % of the total number of the dye structures known to be manufactured and used in the coloration of textiles, leather, plastics and cosmetics. Aside from their traditional usage, azo dyes are known for their therapeutic properties and wide range of applications in biomedicine and pharmaceutical industry. Hereby, the present study aims to investigate the relationship between the chemical structure and pharmacological activity of four azo pyridone dyes taking into account the tautomeric form of dyes. The relationship was determined empirically using appropriate software packages as well as in vitro using the 2, 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method. The results of in silico prediction suggested that all investigated compounds possess good oral bioavailability, while the results of the ABTS assay indicate poor to excellent antioxidant activity depending on the substituent in the phenyl ring. Considering the broad applications of arylazo pyridone dyes, as well as the fact that their relative importance may increase in the future, results obtained in this study serve as a basis for further investigations., Azo boje predstavljaju strukturno najraznovrsniju klasu organskih jedinjenja koja sadrže jednu ili više azo grupa (–N=N–) koje premošćavaju dva organska motiva od kojih je bar jedan aromatičan. Ova grupa sintetskih boja dobija se jednostavnom sintezom koja uključuje reakciju diazo-kuplovanja u visokom prinosu. Da su azo boje od neprocenjivog značaja u različitim granama industrije gde se primenjuju za nijansiranje tekstila, kože, plastike i kozmetičkih proizvoda, govori i činjenica da su zastupljene sa preko 60%. Pored tradicionalne primene, azo boje su poznate i po sve većoj upotrebu u biomedicini i farmaceutskoj industriji. Na osnovu navedeneg, cilj ovog rada je da se detaljnije ispita veza između hemijske strukture četiri azo piridonske boje i njihove farmakološke aktivnosti uzimajući u obzir tautomerni oblik boje. Ova veza određena je empirijski korišćenjem odgovarajućih softverskih paketa kao i in vitro određivanjem njihove antioksidativne aktivnosti primenom ABTS metode. Rezultati in silico predikcije pokazuju da sva ispitivana jedinjenja poseduju dobru oralnu bioraspoloživost i nisku do odličnu antioksidativnu aktivnost u zavisnosti od spupsptituenta u fenilnom jezgru. Uzimajući u obzir širok spektar primene arilazo piridonskih boja kao i činjenicu da će njihov značaj konstantno rasti, rezultati ostvareni u ovom radu predstavljaju interesantnu osnovu za buduća istraživanja.

Ferrocene derivatives are known as antioxidants, antiparasitic, antitumor, antiviral, antibacterial and antifungal agents. In addition to applications in medicinal chemistry and drug design, ferrocene derivatives are of exceptional importance in synthetic organic chemistry, especially in catalytic asymmetric transformations. They are also used in electrochemistry and polymer chemistry, as additives in fuels, as chemosensors in agrochemistry and biosensors of glucose and active components in molecular electronics. To design new antioxidant agents, five ferrocenyl chalcones were synthesized, and fully characterized by melting points, FT-IR, 1H and 13C NMR spectroscopic methods. The synthesized chalcones differ in the nature and the position of the substituent attached to the phenyl group in position 1 of the linear unsaturated carbonyl system. The potential antioxidant activity of the synthesized compounds was evaluated using the ABTS (2,2'-azinobis-(3- ethylbenzothiazoline-6-sulfonic acid) method and IC50 values of the most effective compounds were further determined., Derivati ferocena su poznati antioksidansi, antiparazitici, antitumorni, antivirusni, antibakterijski i antifungalni agensi. Pored primene u medicinskoj hemiji, derivati ferocena su od izuzetnog značaja u sintetičkoj organskoj hemiji, naročito u katalizovanim asimetričnim sintezama. Primenjuju se i u elektrohemiji i hemiji polimera, kao aditivi u gorivima, kao hemosenzori u agrohemiji i biosenzori glukoze i aktivnih komponenata u molekularnoj elektronici. U cilju dizajniranja novih antioksidativnih agenasa, u ovom radu, sintetisano je pet ferocenilhalkona koji su u potpunosti strukturno okarakterisani određivanjem temperature toplenja, FT-IR, 1H i 13C NMR spektroskopskim metodama. Sintetisani halkoni međusobno se razlikuju prema vrsti i položaju supstituenta na fenil-grupi u položaju 1 linearnog nezasićenog karbonilnog sistema. Potencijalna antioksidativna aktivnost ovih jedinjenja procenjena je primenom ABTS (2,2'-azinobis-(3-etilbenzotiazolin-6- sulfonska kiselina) metode i određivanjem IC50 vrednosti najefikasnijih jedinjenja.

A convenient and efficient approach toward the synthesis of six 3-(4-substituted benzyl)-6,7-benzo-1,3-diazaspiro[4.5]decane-2,4-diones (1‒6) by Bucherer-Bergs reaction and further alkylation at position 3 of the hydantoin ring is reported. Further, their chemical structure was confirmed by melting points, elemental analysis, FT-IR, NMR and UV–Vis spectroscopic methods. To gain an insight into interactions which the investigated spirohydantoins establish with their environment, their absorption spectra were recorded in selected solvents of different polarity and the solvent effects on the UV-Vis absorption band positions, intensity and shape, were discussed. Substiuent effects on the solvatochromism of compounds 1−6 were analyzed using the Hammett's equation. Considering the broad applications of hydantoin derivatives, as well as the fact that their relative importance may increase in the future, results obtained in this study serve as a basis for further investigations.

The reduction of water pollution represents one of the priority topics of the EU’s goal to achieve climate neutrality by 2050. Considering this, the concept of reusing the same dyebath for multiple dyeing cycles is proposed. For this purpose, two pyridinium-based azo pyridone dyes with improved solubility and affinity towards different fibers, are used for dyeing wool fabric. It is demonstrated that the dye concentration in wastewater could be reduced up to four times by recirculation of the same dyebath 5 times. The dyed fabrics obtained in each cycle are further characterized regarding color strength (K/S) and ultraviolet protection factor (UPF), while their antioxidant potential is evaluated by ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) test. The results revealed that the proposed concept could be used for obtaining multifunctional wool fabrics by following the principles of sustainable development of reducing the effluent load in wastewater.

In order to improve the performance of theoretical UV–Vis spectra predictions, a theoretical and experimental study of solvatochromic properties of ten azo pyridone dyes has been performed. For quantitative estimation of intermolecular solvent–solute interactions, a concept of the linear solvation energy relationships has been applied using Kamlet-Taft and Catalán models. Theoretical UV–Vis spectra for all dyes have been calculated using four TD-DFT methods in nine different solvents with the aim to define the most reliable model. Finally, new polylinear equations for more accurate theoretical prediction of UV–Vis maxima are developed using empirical Kamlet-Taft and Catalán solvent parameters as additive corrections for specific and nonspecific solvent–solute interactions.

U ovom radu prikazana je sinteza i karakterizacija 6-hidroksi-4-metil-3-(piridinijum-1-il)-2-piridona. Sintetisano jedinjenje dobijeno je u obliku dipol-jona. Spektrofotometrijskom titracijom u rastvoru etanola ispitan je uticaj pH vrijednosti na strukturu jedinjenja. Kako bi se detaljno opisala struktura derivata 2-piridona, eksperimentalno dobijene vrijednosti dobijenih apsorpcionih maksimuma upoređeni su sa kvantno-hemijskim proračunima optimizovanih geometrija i teorijskih UV-Vis spektara pri različitim pH vrijednostima., In this research, synthesis and characterization of 6-hydroxy-4-methyl-3-(pyridinium-1-yl)-2-pyridone was shown. Synthesized compound was achieved in the zwitterionic form. UV-Vis spectrophotometric titration was performed in order to examine the influence of pH values on the structure of the compound. For the purpose of detail characterization of 2-pyridone derivative, experimentally obtained results were compared to quantum-chemical calculations of optimized geometries and theoretical UV-Vis spectra of solution for different pH values.

Considering a significant antioxidant activity of 6-hydroxy-6-methyl-2-pyridones, in this paper four series of arylazo pyridone dyes were subjected to antioxidant ABTS assay. Firstly, preliminary tests were conducted at concentration of 1 mg/ml in order to investigate the effects of different substituents on the dye activity. Based on the preliminary results, dyes with the highest activity were selected for further evaluation of IC50 values and these values were compared with IC50 value of ascorbic acid used as standard. It has been shown that five arylazo pyridone dyes exhibit more potent activity when compared to the ascorbic acid., Uzimajući u obzir značajnu antioksidativnu aktivnost 6-hidroksi-4-metil-2-piridona, u okviru ovog rada ispitana je antioksidativna aktivnost četiri serije arilazo piridonskih azo boja pomoću ABTS testa. U prvom delu su urađeni preliminari testovi aktivnosti pri koncentracij od 1 mg/ml kako bi se ispitao uticaj različitih supstituenata na antioksidativnu aktivnost. Na osnovu ovih rezultata izabrane su boje sa najvećom antioksidativnom aktivnošću, i u drugom delu je za njih određena IC50 vrednost i upoređena sa vrednošću askorbinske kiseline koja je korišćena kao standard. Rezultati su pokazali da pet boja imaju značajniju aktivnost od askorbinske kiseline.

A series of asymmetric bent-core liquid crystals, bearing the stilbene moiety in the side wing, was synthesised and characterised. Structural modifications of the non-stilbene wing resulted in formation of various mesophases. Compounds 1 and 3 with an ester linking group between the phenyl rings in this wing have an enantiotropic non-polar smectic-type mesophase, while compound 2, incorporating the biphenyl moiety, has a ferroelectric SmCaPF phase. The molecules of 2 undergo photoisomerisation in solution under UV irradiation, while the mesophases are unstable and UV irradiation leads to irreversible changes. The mesophases of 1 and 3 do not show any electro-optical switching and polarisation current. Applying low frequency AC voltage on a planarly aligned film of compound 2, smectic domains grow, while the birefringence and an image flickering increase. The observed features of these compounds identify stilbene as an attractive moiety in the design of advanced materials based on bent-core molecules.

Azo dyes are the most important group of organic synthetic dyes. High molar extinction coefficients, which characterize azo compounds, contribute to their wide use in traditional dyeing of various materials, as well as the increasing application in new technologies such as optical devices and solar cells. Numerous studies show that azo dyes based on heterocyclic molecules possess biological activity. Arylazo pyridone dyes belong to the class of disperse dyes, which exhibit antibacterial, antifungal, anticancer and antioxidant properties. In this work, three azo dyes were synthesized starting from 2-, 3- and 4-aminophenol and 3-cyano-6-hydroxy-4-methyl-1-propyl-2-pyridone. The structure of dyes was confirmed by ATR-FTIR, NMR and UV-Vis spectroscopy. The antioxidant activity of compounds was examined by the ABTS method. Physico-chemical descriptors and ADME parameters were determined in silico using SwissADME program., Azo boje su najznačajnija grupa organskih sintetskih boja. Visoki molarni ekstencioni koefici-jenti, koji karakterišu azo jedinjena, doprinose njihovoj širokoj upotrebi kako u tradicionalnom bo-jenju materijala, tako i sve većoj primeni u novijim tehnologijama kao što su optički materijali i solarne ćelije. Mnoga istraživanja pokazuju da azo boje dobijene iz heterocikličnih molekula imaju biološku aktivnost. Arilazo piridonske boje pripadaju klasi disperznih boja koje ispoljavaju antibak-terijsku, antifungalnu, antikancerogenu i antioksidativnu aktivnost. U ovom radu sintetisane su tri azo boje polazeći iz 2-, 3-i 4-aminofenola i 3-cijano-6-hidroksi-4-metil-1-propil-2-piridona. Struk-tura jedinjenja potvrđena je ATR-FTIR, NMR i UV-Vis podacima. Antioksidsativna aktivnost jedinje-nja ispitana je ABTS metodom. Fizičko-hemijski deskriptori i ADME parametari određeni su in silico pomoću SwissADME programa.

Budući da tekstilna industrija predstavlja jednu od glavnih grana industrije, razvoj globalne ekonomije je direktno povezan sa razvojem tekstilne industrije. Sa druge strane, razvoj novih boja je od ključnog značaja za samu tekstilnu industriju. Boje predstavljaju jednu od glavnih zagađujućih materija u otpadnim vodama što predstavlja ekološki problem. Azo boje se nerijetko koriste u industriji kao jedna od najvećih grupa sintetskih boja. Piridinski prsten pokazuje odlično vezivanje za vunu, dok sa druge strane hromofore azo boja daju odlično obojenje. U ovom radu, dvije boje su korišćene za bojenje vune, pri čemu je isti rastvor za bojenje korišćen više puta. Cilj ovog rada je da se smanji udio boja u otpadnoj vodi. Količina boje koja se vezela za vunu, tj. koja je ostala u rastvoru, praćena je UV-Vis spektroskopijom., Considering that the textile industry is an evergrowing industry and its growth directly contributes to economic growth, the interest in developement is strongly dependent with developing new colorants. On the other hand, colored effluent from the textile industry cause water pollution which has an acute effect on the enviorment. The reduction of dye waste and toxicity represents a global problem. As state-of-the art showed pyridine ring allows excellent sublimation fastness for dying wool fibers, wherein azo dyes show brilliant chromophoric strength. Herein, we present the wool dyed with two pyridone based azo dyes bearing pyridinium ring as a substituent. The aim of this work is to reduce the water waste by using the same dyebath for dying wool multiple times. The amount of the dye absorbed on the fabric is determined by the absorption spectra of the dye solution used in the dyebath, followed by the UV-Vis spectra. Therefore the principle of reusing the same dyebath multiple times were determined, wherein the concentration of the dye in the final product is reduced.

U ovom radu prikazane su sinteza i primena dve azo boje na bazi 6-hidroksi-4-metil-3-piridinijum2-piridona. Supstituisani piridon dobijen je Guareši-Torpeovom reakcijom kondenzacije, dok su azo boje sintetisane klasičnim postupkom diazo kuplovanja pri čemu su korišćena dva različito supstituisana anilina. Primenom FTIR, 1H i 13C NMR, UV-Vis i masene spektroskopije dobijena jedinjenja su okarakterisana. U zavisnosti od rastvarača i supstituenta, boje se nalaze u ravnoteži dva tautomerna oblika, hidrazonskog i cviterjonskog, za razliku od literaturnih analoga u kojima se navodi hidrazon-azo anjon ravnoteža. Specifična struktura dobijenih boja omogućava bolju rastvorljivost, pre svega u vodi. Primena se sastoji u bojenju vune pri ranije optimizovanim uslovima bojenja. U ovom radu na osnovu predloženog mehanizma vidi se da, pored očekivanih vodoničnih veza, jon-jon interakcije učestvuju u vezivanju boje za tkaninu. Komparativna studija antioksidativne aktivnosti boja i obojenih tkanina urađena je pomoću ABTS metode., Herein, we report the synthesis and application of two azo dyes based on 6-hydroxy-4-methyl-3- pyridinium-2-pyridone. The substituted pyridone was synthesized via Guareschi-Thorpe condensation, wherein dyes are obtained by the classical reaction of diazo coupling by using two diversely p-substituted anilines. The characterization of the synthesized compounds was carried out by FTIR, 1H and 13C NMR, UV-Vis and mass spectroscopy. These compounds exist in an equilibrium of two tautomeric forms in solution depending on the solvent as well as on the substituent and are water-soluble. It is worth mentioning that the hydrazone form of the dyes is in equilibrium with the zwitterion form of the dyes unlike the literature analogs existing in the anionic form. The application of the dyes consists of dying wool fiber at optimized conditions. The dying mechanism is suggested, wherein it revealed that these like dyes utilize ion-ion interactions next to expected hydrogen bonds. A comparative study on the antioxidant activity of the dyes and the dyestuff was conducted using ABTS assay.

Molecular switches that can undertake reversible switching between two or more different states due to an external triggering stimulus are employed in the fabrication of various optoelectronic devices and smart materials and also found many applications in sensing, molecular self-assembly and photo-controlled biological systems. Photochromic organic molecules possessing bistable characteristics, represent attractive materials for the design of molecular switches owing to their considerable structural diversity, molecular conformations, electronic structures, and the possibility to reversibly alter from one state to another by external stimulations such as light irradiation. In this article, we explore the potential of halogen substituted benzylidenehydantoin-based molecules as novel light-sensitive materials and their solvatochromic behavior by recording the absorption spectra in the selected solvent set and evaluating effects of the specific and nonspecific solvent–solute interactions on the absorption maxima shifts using linear solvatation energy relationship, i.e. equations proposed by Kamlet-Taft and Katalan.. The preliminary results of this study will be promising starting point for design of novel photoactive materials with a broad spectrum of applications., Molekulski prekidači koji se mogu mogu reverzibilno prevoditi iz jednog stabilnog stanja u drugo pod dejstvom nekog spoljašnjeg faktora, uveliko se primenjuju u proizvodnji različitih optičkih i elektronskih uređaja, pametnih materijala kao i raznovrsnih materijala sa biološkom primenom. Bistabilni fotohromni organski molekuli, predstavljaju akraktivne materijale za proizvodnju molekulskih prekidača zahvaljujući svojoj strukturnoj raznovrsnosti, molekulskim konformacijama, elektronskim karakteristikama i mogućnosti prevođenja iz jednog stabilnog stanja u drugo pod dejstvom svetlosti. U ovom radu, proučavana je mogućnost primene halogen supstituisanih benzilidenhidantoina u proizvodnji fotosenzitivnih materijala kao i njihova solvatohromna svojstva određivanjem odgovarajućih apsorpcionih maksimuma u odabranom setu rastvarača, a takođe su analizirani specifični i nespecifični efekti rastvarača na pomeranje apsorpcionih maksimuma primenom Kamlet-Taftove i Katalanove jednačine. Preliminarni rezultati ovog istraživanja predstavljaju dobru polaznu tačku u dizajniranju novih fotoaktivnih materijala sa širokim spektrom primene.

Dyes bearing imino group along with azo one in the structure, present the class of azo-azomethine dyes. Azomethine compounds, known as Schiff bases, find application in biomedical research considering their potential antibacterial, antifungal, antimalaric, anticancer, antiinflammatory and antiviral activity. Furthermore, azo dyes are used in textile fiber dyeing, ink-jet and laser printers, LCDs, photovoltaic devices and metal complexes. With respects to the strong biological activity and a broad spectrum of potential application in industry, herein the microwave assisted synthesis and characterization of three new azo-azomethine dyes is presented. New azo-azomethine dyes were obtained by merging arylazo pyridone dye with different aniline cores resulting in azo-azomethine structure. In addition, tautomerism and solvatochromic properties of the dyes have been discussed., Organske sintetske boje koje u svojoj strukturi sadrže azo i imino grupu predstavljaju klasu azo-azometinskih jedinjenja. Azometinska jedinjenja, poznata kao Schiff-ove baze, imaju značajnu ulogu u biomedicinskim istraživanjima zbog potencijalne antibakterijske, antifungalne, antimalarijske, antikancerogene, antiinflamatorne i antivirusne aktivnosti. Azo-azometinske boje se mogu koristiti u industriji za bojenje tekstilnih vlakana, zatim u LCD ekranima, ink-džet i laserskim štampačima, fotonaponskim uređajima i metalnim kompleksima. U ovom radu prikazana je mikrotalasna sinteza i strukturna karakterizacija tri nove azo-azometinske boje, polazeći iz arilazo piridonske boje i različito supstituisanih anilina. Solvatohromna svojstva i tautomerija novih azo-azometinskih jedinjenja proučavani su u rastvaračima različitih svojstava.

A series of novel 5-(4-substituted phenylazo)-1-carboxymethyl-3-cyano-6-hydroxy-4-methyl-2-pyridones had been synthesized and characterized. The study includes spectral determination of the possible tautomeric forms and the intramolecular hydrogen bonding pattern. The influence of the bifurcated intramolecular hydrogen bond on the spectral properties has been discussed. The dyes exist in hydrazone form both solid state and in most of the employed solvents. Equilibrium between hydrazone and anion forms has been studied in N,N-dimethylformamide and N,N-dimethylacetamide. For quantitative elucidation of solvent effects on UV-Vis absorption maxima, a linear solvation energy relationship concept has been employed using Kamlet-Taft's and Catalan's equations. Antioxidative activity of the synthesized dyes has been chemically tested and two derivatives (hydroxy and methoxy) are qualified as promising antioxidant molecules.

In order to get a better insight into the relationship between molecular structure and photovoltaic performance, six monoazo dye molecules containing benzoic and cinnamic acid moieties were synthesized and their photovoltaic properties were studied. Three of them have not been previously used in solar cells. Spectroscopic measurements of the investigated compounds coupled with theoretical calculations were performed. Short-circuit current density, open-circuit voltage, and fill-factor were determined. It was found that a larger amount of short-circuit current density will be generated if the HOMO-LUMO energy gap is lower, determined by the stability of the molecule and the electronic effect of the donor moiety. Among both series of synthesized dye molecules, the highest obtained values of short-circuit current density were achieved with (2-hydroxynaphthalene-1-ylazo)benzoic acid and (2-hydroxynaphthalene-1-ylazo)cinnamic acid, and thus they were regarded as promising candidates for application in dye-sensitized solar cells.

Six ester and amide derivates of 2,6-dimethyl-4-(substituted)-1,4-dihydropyridine-3,5-dicarboxylic acid have been synthesized in this paper, including: diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicarboxylate, diethyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, diethyl 2,6-dimethyl-4-(4-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, diethyl 4-(2-hydroxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate, diethyl 4-(3-hydroxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate and diethyl 4-(4-hydroxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. Obtained ester derivates were used afterwards as a starting compounds for synthesis of amide derivates, including: 2,6-dimethyl-4-phenyl-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide, 2,6-dimethyl-4-(3-nitrophenyl)-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide, 2,6-dimethyl-4-(4-nitrophenyl)-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide, 4-(2-hydroxyphenyl)-2,6-dimethyl-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide, 4-(3-hydroxyphenyl)-2,6-dimethyl-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide and 4-(4-hydroxyphenyl)-2,6-dimethyl-N3,N5-di(thiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide. Obtained compounds were characterized by melting point, elementary analysis and FT-IR spectroscopy. In order to determine the effect of the substituent, the antioxidative activity assay of obtained 1,4-dihydropyridines was performed by using the DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical scavenging method.

Disazo pyridone dye, 4-methyl-2,6-dioxo-5-(2-(4-(phenyldiazenyl)phenyl)hydrazono)-1,2,5,6-tetrahydropyridine-3-carbonitrile, is synthesised and thoroughly characterised by a combination of experimental and computational approaches. Fourier Transform-infrared and nuclear magnetic resonance (NMR) spectra prove the existence of the hydrazone form in the solid state and in dimethyl sulphoxide, which is also supported by vibrational and NMR theoretical studies. Ultraviolet (UV) spectral properties, as well as solvatochromism in 19 solvents of different polarity, are investigated. In most of the solvents, the dye is solely present in the hydrazone form, whereas in certain solvents, an acid-base equilibrium exists. Excellent agreement between computational and experimental UV-visible data was established. Frontier Molecular Orbital analysis was performed and proved the existence of intramolecular charge transfer through the dye molecule. A molecular electrostatic potential surface was plotted over the optimised geometry to lighten the reactivity of the investigated molecule.