XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
273
T4: P–6
Lead(II) coordination polymers derived from simple heteroaromatic
carboxylic acids: Structural, thermal and luminescence studies
Mateusz Kowalik
1
, Barbara Barszcz
1
, Katarzyna Kazimierczuk
2
,
and Bogumiła Kupcewicz
3
1
Institute of Chemistry, Jan Kochanowski University, 15G Świętokrzyska Str., 25-406 Kielce, Poland,
e-mail: mateuszkowalik.86@gmail.com
2
Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology,
11/12G Narutowicza Str., 80-233 Gdańsk, Poland
3
Department of Inorganic and Analytical Chemistry, Collegium Medicum, Nicolaus Copernicus
University, 2 Jurasza Str., 85-089 Bydgoszcz, Poland
The design and construction of metal coordination polymers (MCPs) is one of the most
active areas of materials research. The intense interest in this field is driven by both their
interesting network topologies and potential applications such as catalysis, sensors, molecular
magnets, drug delivery, adsorption, ion exchange and luminescence materials. Recently, many
efforts had been made in the studies of MCPs, devoted to d- and f-block metal ions complexes.
As an important p-block element, Pb(II) may provide opportunities for the formation of novel
topological arrangements with photochemical and photophysical properties [1]. This is due to
the large ionic radius, the presence of inert electron pair and flexible coordination environment.
On the other hand, heteroaromatic carboxylic acids exhibit multiple coordinating modes
facilitating the formation of multi-dimensional structures and diversified topologies [2].
Herein, we report the solid-state studies of three novel lead(II) coordination polymers
derived from imidazole-4-carboxylic acid (4imCOOH), pyrazole-3-carboxylic acid
(3pyrCOOH), and thiophene-3-carboxylic acid (3tpCOOH). Complex (1), namely
[Pb(4imCOO)
2
(H
2
O)]
n
, is 1D polymer, whereas complexes (2) and (3), namely
[Pb(3pyrCOO)
2
]
n
and {Pb(3tpCOO)
2
(µ-H
2
O)]
n
, respectively, are 2D polymers. Their structures
can be extended into 3D supramolecular frameworks by weak interactions. All three compounds
exhibit interesting fluorescence properties in the solid state (Fig. 1), especially compound (2)
with double fluorescence. Moreover compounds have been characterized by elemental (CHNS),
spectral (FT-IR) and thermal (TGA) analysis.
(2)
λ
ex
=302nm; λ
em
=455nm
(2)
λ
ex
=336nm; λ
em
=535nm
(1)
λ
ex
=422nm; λ
em
=484nm
(3)
λ
ex
=383nm; λ
em
=444nm
400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590
In
te
n
si
ty
(
a
.u
.)
Emission wavelength (nm)
Fig. 1. Emission spectra of (1), (2), and (3) in the solid state.
Keywords: Lead(II) complexes; Coordination polymers; Luminescence properties
References
[1] S.-J. Zhan, Y. Sun, S.-P. Li, G.-M. Tang, Y.-T. Wang, Y.-Z. Cui, Polyhedron (2017) 252.
[2] M.-L. Hu, A. Morsali, L. Aboutorabi, Coordination Chemistry Reviews (2011) 2821.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
274
T4: P–7
Spectroscopic investigations and DFT modelling studies of Eu
3+
complex with 1-(2,6-dihydroxyphenyl)ethanone
Jerzy Hanuza
1
, Maciej Ptak
1
, Radosław Lisiecki
1
, Edyta Kucharska
2
,
Witold Ryba-Romanowski
1
, Krzysztof Hermanowicz
1
, Lucyna Macalik
1
1
Institute of Low Temperature and Structure Research, 2 Okólna str., 50-422 Wrocław, Poland,
e-mail: L.Macalik@int.pan.wroc.pl
2
Department of Bioorganic Chemistry, Faculty of Chemistry and Food Technology, Wrocław
University of Economics, 118/120 Komandorska str., 53-345 Wrocław, Poland
Lanthanide ions chelated with organic ligands have been widely used as laser materials or
luminescent labels in molecular biology and chemistry [1]. Chelating organic ligands act as
photosensitizers because they can play a double role in the formation of lanthanide complexes:
they can be coordinated to one metal ion as well as they can bind Ln(III) ions forming a
polymeric system. The mechanism of photosensitization involves several processes, both inter-
and intra-molecular energy transfer, radiative and non-radiative relaxation of the singlet-excited
states of the ligand to the ground level and quenching and shielding effects. Explanation of the
ligand-to-metal energy transfer mechanism for the complexes with chelating ligands having
their triplet states above the emitting lanthanide levels is based on two processes: the
intermolecular charge transfer and the radiationless intersystem crossing from the excited single
state to triplet ligand state.
In this study, we report and discuss the comprehensive results of vibrational and optical
research performed for Eu
3+
complex with 1-(2,6-dihydroxyphenyl)ethanone (DHPE)
synthesized in the solid state. This ligand contains both acetyl and 2-hydroxyl group, which can
participate in chelation of Eu
3+
ion, as well as 6-hydroxyl group, which can bind biologically
active substances. Geometrical parameters were obtained for the DHPE ligand from the DFT
calculations. Its structure was refined from the calculations in the C1 and Cs symmetries.
Structure determined by Huang et al. [2] from two crystallographically independent molecules
build P-1 triclinic unit cell characterized by the parameters: a = 7.646, b = 8.325, c = 12.803 Å,
α = 73.321º, β = 79.042º, γ = 68.230º, Z = 4. IR and Raman spectra confirm the statements
derived from the results of the chemical analysis. Complexation of the ligand to Eu3+ ions
occurs through one or two hydroxyl groups and, therefore, two types of ligands exist in the
cluster: terminal - having one non-bonded hydroxyl group and bridging that joins two optical
ions forming the H-O-ϕ-O-Eu-O-ϕ-O-Eu-O-ϕ-O-Eu-O-ϕ-O-H system.
Here, we report the employment of the femtosecond laser excitation with a high peak power
to excite the Eu(III) complex with a chelated organic ligand. It is interesting which mechanism
of the ligand-to-metal energy transfer takes place when the femtosecond excitation is used. The
luminescence and dynamics of the excited states depopulation and spectral and energetic
transformation of femtosecond light impulses were studied and energy transfer mechanism
between ligand and the Eu
3+
levels has been proposed. Decay of
5
D
0
→
7
F
J
emission is mono
exponential suggesting that the energy transfer from the ligand occurs from the singlet state
straight to the
5
D
0
level. The lifetime of this level is of a millisecond order what means that the
studied complex can be considered as a promising light-conversion molecular device.
Keywords: Eu
3+
complex; 1-(2,6-dihydroxyphenyl)ethanone; DFT; optical spectra; femtosecond laser excitation
Acknowledgment
Financial support of this work was provided by Polish National Centre of Science under grant No.
2014/15/B/ST5/04730.
References
[1] P. R. Selvin, Ann. Rev. Biophys. Biomol. Struct. 31 (2002) 275.
[2] H-R.
Huang,
X-K
Xia,
Z-G.
She, Y-C.
Lin,
L.L.P.
Vrijmoed,
E.B.
Gareth
Jones,
Acta
Cyst.
E60
(2004) o2509.
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