XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society K N 01
Novel layer-by-layer interfacial [Ni(salen)]-polyelectrolyte
hybrid films
C ristina F reire
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do
Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
acfreire@fc.up.pt
The synthetic derivatisation of [M(salen)]-type complexes with ionic groups can provide
building blocks for the fabrication of hybrid films using the electrostatic layer-by-layer
(LBL) self-assembly technique. This technique affords molecular-level control over
fabrication of thin films by precise control of components assembly.[1] Specifically, it is
an ideal tool for tailoring the properties of multilayer films on the nanometer scale by
electrostatic deposition of charged [M(salen)]-type complexes functionalized with
receptor groups and organic polyelectrolytes with a view to sensor application.
In this work the novel multilayer films containing cationic phosphonium-derivatized
Ni(salen)-type complex and poly(sodium-4-styrenesulfonate (NaPSS) was assembled
onto quartz, mica and Au surfaces using LbL technique, Figure 1. [2] UV-visible and
QCM responses for the multilayer films show regular stepwise growths and the
signature of strong electrostatic interactions between the component layers. Permeability
of the films to the redox probe [Fe(CN) 6 ] 3/4 was studied by cyclic voltammetry (CV)
and electrochemical impedance spectroscopy (EIS). The EIS data were interpreted using
a capillary membrane model (CMM), to yield values of coverage, apparent charge
transfer resistance, double layer capacitance, pore size and diffusion coefficient. The
recognition properties towards Ca 2+ and Ba 2+ of hybrid [Ni(salen)]-PSS LbL thin films
assembled onto Au electrodes was also studied by CV and EIS by using the redox
couple probe [Fe(CN) 6 ] 3-/4- .
N
N
Ni O
O
t-Bu
PPh 3
PPh 3
N
N
Ni
t-Bu
O
O
t-Bu
PPh 3
t-Bu
PPh 3
PSS
Film bilayer (xn)
NaPSS =
SO 3 Na
*
PAH
PSS
Precursor bilayer (x2)
PAHCl =
NH 3 Cl
*
Modified substrate
Figure 1. Schematic representation of LBL films and individual PAHCl, NaPSS and [Ni(salen)] 2+
components.
Acknowledgments: Partially funded by F CT, through project Ref PTDC/QUI/67786/2006.
References
[1] Decher, G. Science 1997, 277, 1232.
[2] Patrício, S.; Cruz, A.I.; Biernacki, K.; Ventura, J.; Eaton, P.; Magalhães, A. L.; Moura, C.;
Hillman , A. R.; Freire, C. Langmuir, 2010, in press: DOI: 10.1021/la1006956
September, 811, 2010. ISEL - Lisbon 18