Jump to main content
Jump to site search

Issue 9, 2017
Previous Article Next Article

Pd2+ fluorescent sensors based on amino and imino derivatives of rhodamine and improvement of water solubility by the formation of inclusion complexes with β-cyclodextrin

Author affiliations

Abstract

Mono- and bis-rhodamine derivatives appended with amino (RhB1) and imino (BRI) groups, respectively, have been designed as colorimetric and fluorescent sensors for the selective detection of Pd2+. In addition, an attempt has been made to improve the water solubility of the probe by synthesizing inclusion complexes of RhB1 with β-cyclodextrin as the host molecule. The resulting probe, RhB1-CD, exhibited exactly the same physicochemical phenomena as the guest molecule RhB1, indicating that complexation with β-CD improved the water solubility of RhB1 without affecting its sensing ability. With increasing concentrations of Pd2+, the absorption (556 nm) and emission (591 nm) intensities of BRI as well as the absorption intensities of RhB1/RhB1-CD (563 nm) increase, whereas the emission intensities of RhB1/RhB1-CD decrease due to fluorescence quenching. Therefore, BRI can act as an “OFF–ON” fluorescent probe switch in CH3CN/H2O (3 : 2 v/v) with a detection limit of 1 μM in solution, whereas RhB1 and RhB1-CD act as “ON–OFF” fluorescent probes in EtOH/H2O (1 : 1 v/v) and water, respectively, with a detection limit of 10 μM. All these probes exhibited high selectivity for Pd2+ and reversibility by treatment with Na2S. In the presence of commonly coexisting metal ions, such as Hg2+, Fe3+, Cu2+ and Al3+, BRI undergoes either catalytic Schiff base hydrolysis or it is unaffected by its affinity to the metal ions. However, Pd2+ can be effectively distinguished by a 12–15 nm bathochromic shift in its emission spectrum when compared with that of other metal ions. A Job's plot revealed that BRI forms 1 : 2 complexes by a spirolactam ring opening mechanism, whereas RhB1/RhB1-CD form 2 : 1 complexes by a ring opening mechanism followed by Pd2+-induced dimerization; the proposed binding mechanisms are presented.

Graphical abstract: Pd2+ fluorescent sensors based on amino and imino derivatives of rhodamine and improvement of water solubility by the formation of inclusion complexes with β-cyclodextrin

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 07 Dec 2016, accepted on 18 Mar 2017 and first published on 20 Mar 2017


Article type: Paper
DOI: 10.1039/C6AN02594C
Citation: Analyst, 2017,142, 1536-1544
  •   Request permissions

    Pd2+ fluorescent sensors based on amino and imino derivatives of rhodamine and improvement of water solubility by the formation of inclusion complexes with β-cyclodextrin

    Y. Zhang, R. Balamurugan, J. Lin, S. Fitriyani, J. Liu and A. Emelyanenko, Analyst, 2017, 142, 1536
    DOI: 10.1039/C6AN02594C

Search articles by author