Iminocoumarine derivatives as potential fluorescent pH sensors

Abstract

Svrha ovog rada jest optička karakterizacija kiselo-baznih svojstava novih derivata iminokumarina u otopinama s ciljem utvrđivanja njihove potencijalne senzorske primjene. Ovim radom određen je utjecaj strukture na svojstva spojeva 2-imino-3-(2-N-metilbenzimidazolil)kromen (IM1), 7-N,N-dietilamino-2-imino-3-(2-N-metilbenzimidazolil)kromen (IM2) i 7-N,N-dietilamino-2-imino-3-(2-N-5-nitro-1H-benzimidazolil)kromen (IM3) te je procijenjena njihova primjenjivost u senzorima za pH. Ispitivani spojevi spektralno su okarakterizirani u univerzalnom puferu i/ili etanolnim otopinama u rasponu vrijednosti pH od 1,00 do 13,00 primjenom UV-vidljive fluorescencijske i apsorpcijske spektrofotometrije. Također, utvrđen je utjecaj otapala na kiselo-bazna i spektralna svojstva ispitivanih spojeva. Spektrofotometrijskom karakterizacijom u otopinama utvrđeno je da se spomenuti derivati iminokumarina mogu koristiti kao potencijalni fluorescentni pH senzori. Točnije, karakterizacijom kiselo-baznih svojstava pokazalo se kako su spojevi 2-imino-3-(2-N-metilbenzimidazolil)kromen (IM1) i 7-N,N-dietilamino-2-imino-3-(2-N-metilbenzimidazolil)kromen (IM2) puno bolji pH senzori od 7-N,N-dietilamino-2-imino-3-(2-N-5-nitro-1H-benzimidazolil)kromena (IM3). Važno je također spomenuti da su spomenuti spojevi okarakterizirani na Zavodu za opću i anorgansku kemiju kao potencijalne solvatokromne probe te kao optički senzori u otopinama i plastificiranoj polimernoj matrici.The main idea of this work is the characterisation of novel iminocoumarine derivatives in order to determine their applicability as pH sensors. Structure – property relation and effect of pH is determined for compounds 2-imino-3-(2-N-methylbenzimidazolyl)chromen (IM1), 7-N,N-diethylamino-2-imino-3-(2-N-methylbenzimidazolyl)chromen (IM2) and 7-N,N-diethylamino-2-imino-3-(2-N-5-nitro-1H-benzimidazolyl)chromen (IM3) Compunds were characterised in the universal buffer solutions and/or ethanol solutions in the pH range 1,00 to 13,00 by UV-Visible flourescence and absorption spectrophotometry. Also, effect of solvent on acid - base properties of examined compounds was investigated. Examined iminocoumarine derivatives can be used as a potential fluorescent pH sensors. It has been shown that compounds 2-imino-3-(2-N-methylbenzimidazolyl)chromen (IM1) and 7-N,N-diethylamino-2-imino-3-(2-N-methylbenzimidazolyl)chromen (IM2) are better pH sensors than 7-N,N-diethylamino-2-imino-3-(2-N-5-nitro-1H-benzimidazolyl)chromen (IM3). Also, it is important to mention that investigated compounds are previously characterised as a potential solvatochromic probes and optical sensors in solutions and polymer matrices