This document discusses the use of 1,2-Bis(N’-benzoylthioureido)benzene (BBTB) as an ionophore for detecting lead cations. Experimental studies using UV-Vis spectrophotometry showed that BBTB forms a 2:1 complex with lead, indicated by a breakpoint in the absorbance versus concentration plot. Theoretical DFT studies calculated binding energies and optimized structures, confirming complex formation between BBTB and lead cations. Overall, BBTB was found to selectively bind lead cations, demonstrating its potential as a selective ionophore sensor for lead quantification.

1. ABIGAIL ASHA ABRAHAM
UNIVERSITY OF MALAYA
26/12/2014

2. Found everywhere and affects
several organs in human.
Causes health problems in
children and adults.
Many supplies, so it can be
found excessively.

3. Sources
of lead
Batteries
Alloys
Anticorrosion
coatings
Lead based
paints
Traditional
medicines
Lead pipes,
brass
plumbing
fixtures

5. Benzo-subsituted
macrocyclic diamides
Butyl-3-2(2-
phenylhydrazono)indolin-
2-one
Podand derivatives
Derivatives of
bis(phenylhydrazono-1H-
tetrazol-5-yl-
acetonitriles)

6. Ligands from thiourea derivatives are able to form
complexes with metals.
Heavy metals shows great affinity for soft
coordination centers.
Synthesized ionophore consist N and S atoms which
provides donor site to coordinate metal ions.

7.  1,2-Bis(N’-benzoylthioureido)benzene (BBTB)

8. • GAUSSIAN 09 program
• To obtain optimized
structure of the ligand
and complex.
Theoretical
study
• UV-Vis
spectrophotometryExperimental
study

9. UV-Vis absorption spectra: (a) 1.0×10-3M Pb2+, (b) 2.0×10-4M 1,2-
bis(N’-benzoylthioureido) benzene ligand and (c) mixture of
ionophore and Pb2+ cation.

10. Spectrum of lead (L) shows a slight absorption
maximum at 300nm
Ligand spectrum shows two absorption maximum
at 320 and 350nm.
Addition of lead (II) to BBTB ligand, the
absorption band shifts to 300nm and its intensity
increases.

11. UV-Vis absorption spectra of BBTB ligand (2.3×10-6 M) in 1:1 MeOH:AN
mixture in the presence of increasing concentration of lead(II) and
absorbance versus the [Pb2+]/[BBTB] molar ratio plots.

12. The linear plot of absorbance versus the
molar ratio of [Pb2+]/[ BBTB] shows a
breaking point at 0.5
Formation of 2:1 [Pb: BBTB] complex.
BBTB + 2 Pb2+ BBTB(Pb)2

13. GAUSSIAN 09 program based on the
density functional theory
To understand the functional interaction
between BBTB ligand some metal cations
B3LYP / GENECP basis set was applied

14. BBTB ligand Complex with Pb2+ cation

15. Geometric parameters for optimized free and complexed BBTB
ligand with Pb2+ cations.

16. Comparison of geometric paramatersof BBTB with lead (II) ion
and BBTB with other studied cations.

17. Table: Binding energies ∆E, of BBTB with various cations by DFT
method, where EBTBT is -2018.976 (Hartree).

18.  The binding energies, ∆E in the complexes
process between BBTB ligand and cations in
vacum are calculated according to the
following equation:

19. BBTB was applied as an ionophore for investigation
the complex reactions with some cations.
The reaction between BBTB ionophore and lead (II)
cations investigated by UV-Vis
With the purpose to elucidate the obtained
experimental results, a density functional theory
(DFT) study was conducted
The results demonstrate that the application of
BBTB as a selective ionophore created cation-
sensor for the quantification of lead (II) cations.