Bu\u0161i\u0107, V.; Roca, S.; Vrande\u010di\u0107, K.; \u0106osi\u0107, J.; Siber, T.; Ga\u0161o-Soka\u010d, D. Comparison of Conventional and Ultrasound-Assisted Green Synthesis of Quaternary Pyridinium Salts and Their Antifungal Activity. Appl. Sci. 2026, 16, 3470. https:\/\/doi.org\/10.3390\/app16073470<\/p>\n\n\n\n
Usporedba konvencionalne i ultrazvu\u010dno potpomognute zelene sinteze kvaternih piridinijevih soli i njihove antifungalne aktivnosti<\/p>\n\n\n\n
OPIS ISTRA\u017dIVANJA<\/p>\n\n\n\n
Ovo istra\u017eivanje bavi se razvojem ekolo\u0161ki prihvatljivih metoda sinteze kvaternih piridinskih soli, s naglaskom na principe zelene kemije, te njihovom antifungalnom aktivno\u0161\u0107u. Cilj rada bio je ispitati u\u010dinkovitost kvaternizacijskih reakcija izme\u0111u piridin-3- i piridin-4-aldoksima i supstituiranih 2-bromoacetofenona u razli\u010ditim reakcijskim medijima, uklju\u010duju\u0107i konvencionalna otapala (etanol) i zelene alternative poput niskotemperaturnih eutektic\u030cnih otapala (DES), uz primjenu ultrazvu\u010dne sinteze.<\/p>\n\n\n\n
DES-ovi su pripremljeni kombinacijom kolin-klorida kao akceptora vodikove veze i razli\u010ditih donora (urea, glicerol te organske kiseline). Njihova prednost le\u017ei u biorazgradivosti, niskoj toksi\u010dnosti i jednostavnoj pripremi bez stvaranja zna\u010dajnog otpada. U istra\u017eivanju je po prvi put ispitan njihov potencijal u kvaternizacijskim reakcijama, pri \u010demu su pokazali ograni\u010denja zbog viskoznosti i slabije difuzije reaktanata, \u0161to je rezultiralo ni\u017eim prinosima u usporedbi s klasi\u010dnim otapalima.<\/p>\n\n\n\n
Rezultati su pokazali da ultrazvu\u010dna sinteza zna\u010dajno pobolj\u0161ava u\u010dinkovitost reakcije u odnosu na konvencionalne metode, skra\u0107uju\u0107i vrijeme reakcije s 3 sata na 1 sat te pove\u0107avaju\u0107i ukupne prinose. Najbolji rezultati postignuti su kombinacijom ultrazvuka i DES-a, posebno u sustavu kolin-klorid:urea, koji se pokazao kao najpovoljniji medij za kvaternizaciju.<\/p>\n\n\n\n
Sintetizirano je ukupno 18 spojeva, \u010dija je struktura potvr\u0111ena spektroskopskim metodama (NMR, IR, MS i elementarna analiza). Svi spojevi su zatim ispitani na antifungalnu aktivnost prema \u010detiri fitopatogena: Botrytis cinerea, Fusarium culmorum, Macrophomina phaseolina i Sclerotinia sclerotiorum<\/em>. Rezultati su pokazali zna\u010dajnu inhibiciju rasta micelija, pri \u010demu je B. cinerea<\/em> bio najosjetljiviji (do 70,7% inhibicije), dok je F. culmorum<\/em> pokazao najmanju osjetljivost (\u226432%).<\/p>\n\n\n\n Zanimljivo je da ni\u017ea koncentracija spojeva (10 \u00b5g\/mL) u nekim slu\u010dajevima pokazuje ve\u0107u u\u010dinkovitost od vi\u0161e koncentracije, \u0161to se obja\u0161njava fizikalno-kemijskim svojstvima i mogu\u0107om agregacijom molekula. Statisti\u010dka analiza potvrdila je zna\u010dajne razlike izme\u0111u spojeva i patogena, pri \u010demu su pojedini derivati pokazali izra\u017eeniji antifungalni potencijal. Zaklju\u010dno, rad pokazuje da kombinacija ultrazvuka i DES-a predstavlja odr\u017eivu i u\u010dinkovitu alternativu klasi\u010dnim metodama sinteze, uz istovremeno dobivanje biolo\u0161ki aktivnih spojeva s potencijalnom primjenom u za\u0161titi bilja.<\/p>\n\n\n\n Comparison of Conventional and Ultrasound-Assisted Green Synthesis of Quaternary Pyridinium Salts and Their Antifungal Activity<\/p>\n\n\n\n ABOUT THIS RESEARCH<\/p>\n\n\n\n This study focuses on the development of environmentally friendly synthesis methods for quaternary pyridinium salts, emphasizing the principles of green chemistry, as well as their antifungal activity. The aim was to investigate the efficiency of quaternization reactions between pyridine-3- and pyridine-4-aldoximes and substituted 2-bromoacetophenones in different reaction media, including conventional solvents (ethanol) and green alternatives such as deep eutectic solvents (DES), with the assistance of ultrasound irradiation.<\/p>\n\n\n\n DES were prepared by combining choline chloride as a hydrogen bond acceptor with various donors (urea, glycerol, and organic acids). Their advantages include biodegradability, low toxicity, and simple preparation without significant waste generation. In this study, their potential in quaternization reactions was investigated for the first time. However, they showed certain limitations due to high viscosity and reduced diffusion of reactants, which resulted in lower yields compared to conventional solvents.<\/p>\n\n\n\n The results demonstrated that ultrasound-assisted synthesis significantly improves reaction efficiency compared to conventional methods, reducing reaction time from 3 hours to 1 hour while increasing overall yields. The best results were achieved by combining ultrasound irradiation with DES, particularly in the choline chloride:urea system, which proved to be the most effective medium for quaternization.<\/p>\n\n\n\n A total of 18 compounds were synthesized and structurally confirmed using spectroscopic techniques (NMR, IR, MS, and elemental analysis). All compounds were subsequently tested for antifungal activity against four phytopathogenic fungi: Botrytis cinerea, Fusarium culmorum, Macrophomina phaseolina, and Sclerotinia sclerotiorum<\/em>. The results showed significant inhibition of mycelial growth, with B. cinerea<\/em> being the most sensitive species (up to 70.7% inhibition), while F. culmorum<\/em> showed the lowest sensitivity (\u226432%).<\/p>\n\n\n\n Interestingly, in some cases, lower concentrations of the compounds (10 \u00b5g\/mL) exhibited higher antifungal activity than higher concentrations. This behavior is attributed to physicochemical properties of the compounds and possible aggregation effects. Statistical analysis confirmed significant differences among compounds and pathogens, with certain derivatives showing particularly strong antifungal potential. In conclusion, the study demonstrates that the combination of ultrasound irradiation and deep eutectic solvents represents a sustainable and efficient alternative to classical synthetic methods, while also yielding biologically active compounds with potential applications in plant protection.<\/p>\n","protected":false},"excerpt":{"rendered":" Bu\u0161i\u0107, V.; Roca, S.; Vrande\u010di\u0107, K.; \u0106osi\u0107, J.; Siber, T.; Ga\u0161o-Soka\u010d, D. Comparison of Conventional and Ultrasound-Assisted Green Synthesis of Quaternary Pyridinium Salts and Their Antifungal Activity. Appl. Sci. 2026, 16, 3470. https:\/\/doi.org\/10.3390\/app16073470 Usporedba konvencionalne i ultrazvu\u010dno potpomognute zelene sinteze kvaternih piridinijevih soli i njihove antifungalne aktivnosti OPIS ISTRA\u017dIVANJA Ovo istra\u017eivanje bavi se razvojem ekolo\u0161ki prihvatljivih metoda sinteze kvaternih … <\/p>\n