Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/70643
Title: 1,3,5-triarylpyrazolines - pH-driven off-on-off molecular logic devices based on a “receptor1-fluorophore-spacer-receptor2” format with internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms
Authors: Zammit, Ramon
Pappova, Maria
Zammit, Esther
Gabarretta, John
Magri, David C.
Keywords: Fluorescence
Charge transfer
Ternary system
Issue Date: 2015
Publisher: Canadian Science Publishing
Citation: Zammit, R., Pappova, M., Zammit, E., Gabarretta, J., & Magri, D. C. (2015). 1, 3, 5-Triarylpyrazolines—pH-driven off-on-off molecular logic devices based on a “receptor1-fluorophore-spacer-receptor2” format with internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms. Canadian Journal of Chemistry, 93(2), 199-206.
Abstract: The excited state photophysical properties of the 1,3,5-triarylpyrazolines 1–4 were studied in methanol and 1:1 (v/v) methanol–water, as well as 1:4 (v/v) methanol–water and water by fluorescence spectroscopy. The molecules 2–4 incorporate a “receptor1-fluorophore-spacer-receptor2” format while 1 is a reference compound based on a “fluorophore-receptor1” design. The molecular probes operate according to photoinduced electron transfer (PET) and internal charge transfer (ICT) processes. At basic and neutral pHs, 2–4 are essentially nonfluorescent due to PET from the electron-donating dimethylamino moiety appended on the 5-phenyl ring to the excited state of the 1,3,5-triarylpyrazoline fluorophore. At proton concentrations of 10−3 mol/L, the dimethylamino unit is protonated resulting in a strong blue fluorescence about 460 nm with significant quantum yields up to 0.54. At acid concentrations above 10−2 mol/L, fluorescence quenching is observed by an ICT mechanism due to protonation of the pyrazoline chromophore. Symmetrical off-on-off fluorescence–pH profiles are observed, spanning six log units with a narrow on window within three pH units. Hence, 2–4 are novel examples of ternary photonic pH sensing molecular devices.
URI: https://www.um.edu.mt/library/oar/handle/123456789/70643
Appears in Collections:Scholarly Works - FacSciChe

Files in This Item:
File Description SizeFormat 
1_3_5_triarylpyrazolines.pdf
  Restricted Access
1.54 MBAdobe PDFView/Open Request a copy


Items in OAR@UM are protected by copyright, with all rights reserved, unless otherwise indicated.