ISMSC 2007 - Università degli Studi di Pavia

A novel pyrenyl appended tricalix[4]arene with enhanced fluorescence for
Al 3+ PSA 51
sensing.
Amel Ben Othman, a,b Jeong Won Lee, c Rym Abidi, b,* Jong Seung Kim, c,* and Jacques Vicens a,*
a
ULP-ECPM, UMR 7178-LC4-IPHC, Laboratoire de Conception Moléculaire, 25, rue Becquerel,
F-67087 Strasbourg, Cédex, France
b
Université de Bizerte, Facultés des Sciences, 7021 Zarzouna-Bizerte, Tunisie
c
Department of Chemistry, Dankook University, Seoul 140-714, Korea
Aluminium is the most widely distributed metal in the environment and is extensively used in
modern life. It is neurotoxic and can induce many diseases, such as Alzheimer’s disease,
Parkinson’s disease and amyotrophic lateral sclerosis, etc. Compared to other metal cations,
chemosensors aimed to detect and evaluate concentrations of aluminium are not so developed
and the need to prepare molecular probes for this metal exists. In the present work we
synthesized novel pyrenyl appended tricalix[4]arene which presents enhanced fluorescence
during Al 3+ sensing. We have shown the need for the receptor to be tripodal for complexation to
occur. Of importance seems the fact that the chelating part of the receptor is separated from the
signalling moieties. In our case the separation is made by the use of calixarenes which are
selectively 1,3-dialkylated.
Tren- N-tricalix[4]arene appended with three pyrenyl showed an enhanced fluorescence in the
presence of Al 3+ and at less extend of In 3+ in acetonitrile. The ligand was shown to form a 1:1
complex with Al 3+ , the metal cation being located in the tren part. The association constant (Ka)
of tren- N-tricalix[4]arene for the Al 3+ cation was calculated to be 8.7 × 10 3 M -1 in acetonitrile.
The present work develop the synthesis of pyrene amide calix[4]arenes as chemosensors for
the detection of cations and anions.
We used the 1 H NMR technique to locate Al 3+ in the ligand cavity. The NMR solution was
submitted to the MALDI TOF technique to show evidence of a 1:1 complex in the solution with
m/z = 3051.541 (Ligand + Al 3+ -3H + ).
O
O
OH
OH
HN
O
H
N
O
O NH
N
HN O
O
HN
OH
OH
O
O O
NH
HO
HO
O
O
Al 3+
N
N
Al
N
O
O
O
OH
OH
O
HN
O
3+
N O
O
OH
OH
H
N
O
O
O
HO
HO
O
NH
O
Plausible mode of complexation of Al 3+ cation by tren- N-tricalix[4]arene.
Intramolecular FRET triggered Hg 2+ PSA 52
ion sensing in tricalix[4]arene system
Amel Ben Othman, a,b Jeong Won Lee, c Rym Abidi, b,* Jong Seung Kim, c,* and Jacques Vicens a,*
a
ULP-ECPM, UMR 7178-LC4-IPHC, Laboratoire de Conception Moléculaire, 25, rue Becquerel,
F-67087 Strasbourg, Cédex, France
b
Université de Bizerte, Facultés des Sciences, 7021 Zarzouna-Bizerte, Tunisie
c
Department of Chemistry, Dankook University, Seoul 140-714, Korea
It is well known that mercury is a very volatile element, and its vapors can be a dangerous
source of air pollution, thus representing a serious risk for human health. So, the design of
chemosensors able to selectively recognize and sense mercury has attracted considerable
interests. The main issue in designing effective sensor is to easily convert molecular recognition
into photochemical changes with a high selectivity and sensitivity. For the chemosensors, the
photochemical changes in the sensing modules are mainly based on the photo-induced electron
transfer (PET), Chelation-Enhanced Fluorescence (CHEF) and fluorescence resonance energy
transfer (FRET). Taking our interest into account of the fluorescence resonance energy transfer
a novel sensor for Hg 2+ ion based on switchable FRET has been investigated.
O O
O
O
OH HN NH HO
OH
HO
O
N
O
O
NH
N
O
N
O
N
HN
O
O O
O
O
OH HN NH HO
OH
HO
OH
N
HO
1 2
Upon the addition of various metal perchlorate, ligand 1 exhibits a selectivity for Hg 2+ and Pb 2+
ions concerning new absorption band at 555 nm. We also observed a visual change from
colorless to pink with Hg 2+ or Pb 2+ ion in CH3CN. From the titration profile, association constants
of 1 for Hg 2+ and Pb 2+ ion are found to be 39,070 and 9,850, respectively. Addition of Al 3+ ion to
1 gave an increase of the pyrene emission by the CHEF effect, but no change of rhodamine.
This may indicate that the Al 3+ ion is coordinated only to the tetraamide-tren part excluding to the
rhodamine part. Compared to 1, 2 shows only a small change of the rhodamine band upon Hg 2+
ion binding. So, one can conclude that the FRET event takes place in 1·Hg 2+ complex.
N
O
N
O
N