ISMSC 2007 - Università degli Studi di Pavia

OP 13
Anion sensing in consumer products: from multi-electrolytes to toothpaste
Pavel Anzenbacher, Jr. and Manuel A. Palacios
Center for Photochemical Sciences and Department of Chemistry, Bowling Green State
University, Bowling Green, Ohio 43403, USA. E-mail: pavel@bgsu.edu
The important role anions play in biological and industrial processes demands reliable sensing
of anions in multi-analyte environments. The performance of sensor arrays utilizing pattern
recognition operating in multi-analyte environments may be dramatically improved by utilizing a
printable polymer host doped with sensors selective to key components of the mixture. This
way, one can perform fast screening of receptor and sensor moieties, for example by InkJet
printing of the sensor-polymer mixtures (Sens-Ink) on various surfaces that include glass and
plastic. The use of a polymer interface layer between the solid support and bulk aqueous
analyte makes it possible to utilize anion sensors that are otherwise insoluble in water. This
approach is shown on examples of optical sensors utilizing an analyte-specific change in color
or luminescence in the presence of an analyte. The rapid pre-screening allows for assembling
small sensor arrays that are biased toward key components of a particular multianalyte. To
demonstrate this aspect, we will show examples of arrays utilizing less than ten elements
capable of sensing inorganic anions, biological phosphates such as AMP and ATP,
distinguishing between various non-steroidal anti-inflammatory drugs, or identifying different
toothpaste brands based on their anion content.
[1] M. A. Palacios, R. Nishiyabu, M. Marquez and P. Anzenbacher, Jr.: Supramolecular
Chemistry Approach to the Design of High-Resolution Sensor Array for Multi-Anion Detection in
Water. J. Am. Chem. Soc. 2007, 129, in press (ja0704784).
A molecular gate based on a porphyrin and a silver lock
Aurélie Guenet a , Ernest Graf a , Mir Wais Hosseini a , Nathalie Kyritsakas a , Lionel Allouche b
a LCCO UMR CNRS 7140, Université Louis Pasteur, Institut Le Bel, 4 rue Blaise Pascal 67000
Strasbourg, France
b Service Commun de RMN FR CNRS 2351 Université Louis Pasteur, Institut de Chimie, 1 rue
Blaise Pascal 67000 Strasbourg, France
Design of molecular switches, rotors and motors is a challenging task that has attracted
considerable attention over the past fifteen years. [1] Our approach is based on a molecular
gate which consists of a hinge (purple) and a handle (grey) each bearing a single coordinating
site (scheme 1).
Open Closed
Scheme 1: Schematic representation of the molecular gate
The hinge is composed of a tin(IV) porphyrin bearing a 4-pyridyl group at one of the four meso
positions. The handle is formed from a central pyridine moiety bearing two terminal phenoxo
ligands spaced by two oligoethylene glycol units permitting the connection of the handle to the
hinge through coordination to the Sn atom (scheme 2).
N
O
N
N Sn N
N
O
O O
O O
O
O
O
N Sn N
AgOTf
+ - NEt4 Br
N
N N
O
O
O
O
O
O O
Scheme 2
In solution, the handle rotates freely around the hinge. The gate is in its open position. However,
in the presence of a silver cation, both pyridine units of the hinge and the handle simultaneously
bind to the cation leading to the closing of the gate. Thus, the system behaves as a molecular
gate controlled by the locking action of Ag(I). The functioning of the gate is based on
complexation / decomplexation processes induced by external chemical stimuli (addition of
silver cation and bromide anion). These processes as well as their reversibility were studied by
multidimensional 1 H NMR experiments.
The molecular gate presented here is the first step towards the synthesis of a rotor based on a
hinge equipped with several coordinating sites and a handle bearing a single coordinating unit.
The introduction of two or more coordination sites (regarded as stations) on the hinge should
allow the handle to travel from station to station.
[1] V. Balzani, A. Credi, F.M. Raymo, J.F. Stoddart, Angew. Chem. Int. Ed., 2000, 39, 3348-
3391, Special Issue, Acc. Chem. Res., 2001, 34, 409-522, W.R. Browne, B.L. Feringa, Nature
nanotechnology, 2006, 1, 25-35, E.R. Kay, D. A. Leigh, F. Zerbetto, Angew. Chem. Int. Ed.,
2007, 46, 72-191.
O
N
O
Ag
O
O
N
OP 14