Nicotinic acid and its isomers as capping ligands and sensitizers for Tb³⁺ doped CaF₂ nanocrystals

Kumar, Gaurav (2022) Nicotinic acid and its isomers as capping ligands and sensitizers for Tb³⁺ doped CaF₂ nanocrystals. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Gaurav Kumar (17MS155)) 17MS155_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

In this work, we have synthesized nicotinic acid and its isomers picolinic acid and iso-nicotinic acid capped CaF₂ Tb³⁺ doped nanocrystals (NCs) and studied their photo physical properties. All their capping ligands are able to attach strongly to the surface of Tb³⁺-doped CaF₂ nanocrystals as well as sensitize the Tb³⁺ emission resulting in strong green emission close 542 nm. All the three ligands, picolinic acid capped NCs showed an enhancement up to 10 times. The enhancement in the emission intensity of Tb³⁺ ions is attributed to efficient energy transfer between the ligand energy levels to excited energy level of Tb³⁺ ions. Interestingly, this energy transfer is selectively quenched upon the addition cupric ion leading to the reduction in the green emission intensity. The selective quenching is due to selective bond between pyridine nitrogen and cupric ions. The detection limits (for the 3σ/slope criterion) are 0.75μM for the cupric ions. The reduction in the emission intensity is found to be very selective which is verified by the addition of other cations like (Fe²⁺,Al³⁺, Mn²⁺,Sn²⁺,Cu²⁺,Bi³⁺,Co²⁺,Ba²⁺, Pb²⁺, Zn²⁺,Cd²⁺,Mg²⁺) resulting hardly any alteration to the Tb³⁺ emission intensity. The study clearly implies that the resonance energy transfer (RET) using Tb³⁺-doped nanoparticles can serve as a tool to selectively detect cupric ions.

Actions (login required)

View Item