Journal of Molecular Structure
Two Gd(III) coordination polymers based on a flexible tricarboxylate:
Syntheses, structures, luminescence and catalytic properties
,
*
,
,
, **
Yu Zhu a 1, Min Zhu b 1, Pan Liu c, Li Xia c, Yunlong Wu c, Jimin Xie c
a College of Pharmacy and Chemistry & Chemical Engineering, Taizhou University, Taizhou, 225300, China
b Hanlin College, Nanjing University of Chinese Medicine, Taizhou, 225300, China
c School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two Gadolinium coordination polymers {[Gd$(TTTA)$(H2O)2]$2H2O}n (1) and [Gd$(TTTA)$DMF]n (2) have
been synthesized based on Gd(NO3)3$6H2O and the flexible tripodal ligand 2,20,200-[1,3,5-triazine-2,4,6-
triyltris(thio)]tris-acetic acid (H3TTTA) under hydrothermal conditions. In the structure of 1, the tri-
dentate TTTA3ꢀ ligands connect the dimeric metal centers into an infinite one dimensional chain. While
2 shows a two dimensional network with tridentate TTTA3ꢀ ligands. The two complexes all quench the
emission spectra after coordinated to the Gd3þ ions. The catalytic results indicate that two complexes
show excellent activities for the cyanosilylation of benzaldehyde and its derivatives. Besides, 2 is better
than 1 in the catalytic reactions due to more possibility of metal open sites.
Received 24 March 2016
Received in revised form
4 September 2016
Accepted 26 September 2016
Available online 28 September 2016
Keywords:
Flexible ligand
Crystal structure
Luminescence
Cyanosilylation
© 2016 Elsevier B.V. All rights reserved.
1. Introduction
networks for potential applications in selective catalysis and sep-
aration [13e16]. Flexible carboxylate thio-triazine-based ligands,
Recently, the coordination polymers (CPs) based on metal ions
and multidentate ligands have been increasingly accelerated
developed and sustained with extensively studies on potential
applications in gas storage and separation, catalysis, luminescence,
magnetism and so on [1e6]. In the construction of CPs, multi-
dentate organic ligands connect the metal ions into generate
multidimensional frameworks through the coordinated bonds and
supramolecular interactions [7,8]. Up to now, the design of CPs has
been more limited the case where the ligand is rigid [9e12]. The
coordinated sites of the rigid ligands are fixed and the targeted
frameworks are predicable easily. More importantly, the structures
of CPs with rigid ligands are relatively simple for constructions. But
to flexible ligands, the rotations of ligands for self-adaption in self-
assembly make the constructions of CPs more difficult. Besides, the
difficulties to control the targeted frameworks also make the flex-
ible ligands less developed. However, after overcoming these
challenges, the advantages of flexible ligands will be exhibited with
unpredictable chiral, helical frameworks and high-nuclear
which have been less developed in the past, may give us a new way
to construct various CPs with different metal ions for novel topol-
ogies and interesting applications [17e20]. In previous studies, we
selected the flexible tripodal 2,20,200-[1,3,5-triazine- 2,4,6-triyl-
tris(thio)] tris-acetic acid (H3TTTA) as the main ligand and obtained
several CPs in the applications on chemical sensor and heteroge-
neous catalyst [17,18]. H3TTTA owns a planar triazine ring with
three flexible arms which can be self-adaptive through adjusting
the orientations and sizes of the SeCeC angles to coordinate the
metal ions. Meanwhile, the different degrees of protonation will
cause different coordination sites which will achieve abundantly
networks [21e24]. Controlling the reaction condition, interesting
and multi-dimensional structures and unexpected applications can
be obtained with H3TTTA. Not only that, S atoms in the ligand can
act as S/HeO hydrogen bonding and noncovalent S/S weak in-
teractions in the structure [25]. Meanwhile, the SH groups in the
frameworks can also be seen as the free functional organic sites
(FOSs) which should be an important strategy for metal ions or
molecules sorption in the past few years [17,25e27].
Herein, H3TTTA and Gd3þ ions were selected to construct novel
lanthanide coordination polymers by self-assembly. Finally two
different Gd coordination polymers were obtained and called
{[Gd$(TTTA)$(H2O)2]$2H2O}n (1) and [Gd$(TTTA)$DMF]n (2). We
* Corresponding author.
** Corresponding author.
Author contributions: Y. Zhu and M. Zhu contributed equally.
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0022-2860/© 2016 Elsevier B.V. All rights reserved.