Synthesis of Phenolphtalein-Based Fluorescence Sensor and Investigation of Its Optical Properties Towards Heavy Metals in Aqueous Media

Abstract

In this study, phenolphthalein-based ligand L compound derivatized with R-2-phenylglycinol was synthesized and its structure was characterized by 1H-NMR and FTIR spectroscopy. Optical properties of the prepared phenolphthalein-based ligand L towards different cations were investigated by fluorescence and UV-VIS spectroscopy in ethanol-water (95/5; v/v) medium. It was determined that ligand L showed a strong, selective and sensitive fluorescence at 454 nm towards the Zn2+ cation compared to other cations. The mechanism of ligand L complexing with Zn2+ was explained by ICT and inhibition of C=N isomerization and complexation. Fluorescence titration study was performed between ligand L and Zn2+ cation and necessary sensor parameters were examined. According to the Job plot, the complexing ratio was determined as 1:2. The binding constant was calculated as 1.72 x 1012 (logK= 12.24) according to the Benesi-Hildebrand equation. The limit detection value was calculated as 118 nM. When all data were examined, it was determined that the prepared phenolphthalein-based ligand L showed selective and sensitive fluorescence sensor properties against Zn2+ cation.

Bu çalışmada (R)-(-)-2-fenilglisinol ile türevlendirilmiş fenolftalein tabanlı ligand L bileşiği sentezlendi ve yapısı 1H-NMR ve FTIR spektroskopisi ile karakterize edildi. Hazırlanan fenolftalein tabanlı ligand L’nin farklı katyonlara karşı optik özellikleri etanol-su (95/5; v/v) ortamında floresans ve UV-GB spektroskopisi ile incelendi. Ligand L’nin Zn2+ katyonuna karşı diğer katyonlara göre 454 nm’de şiddetli, seçimli ve hassas bir floresans özelliği gösterdiği belirlendi. Ligand L’nin Zn2+ ile kompleksleşme mekanizması, ICT ve C=N izomerizasyonunun engellenmesi ve kompleksleşme ile açıklandı. Ligand L ile Zn2+ katyonu arasında floresans titrasyon çalışması gerçekleştirildi ve gerekli sensör parametreleri incelendi. Job grafiğine göre, kompleksleşme oranı 1:2 olarak belirlendi. Bağlanma sabiti Benesi-Hildebrand denklemine göre 1,72x1012 (logK= 12,24) olarak hesaplandı. Limit algılama değeri 118 nM olarak hesaplandı. Tüm veriler incelendiğinde, hazırlanan fenolftalein tabanlı ligand L’nin Zn2+ katyonuna karşı seçimli ve hassas floresans sensör özellikleri gösterdiği belirlendi.