Synthesis, structure and photoluminescence properties of lanthanoid coordination polymers based on tetra(3,5-dicarboxyphenoxymethyl)methane

Article abstract of DOI:10.1016/j.poly.2016.10.050

A series of isostructural lanthanoid coordination polymers with the formula [Ln₂(H₆L)(H₄L)(H₂O)₂]_n(XL-Ln; Ln = Sm^III, Eu^III, Gd^III, Tb^III, Dy^III; H₈L = tetra(3,5-dicarboxyphenoxymethyl)methane) has been synthesized. The compounds (except XL-Gd) exhibit the characteristic emission of trivalent lanthanoid ions under UV irradiation. By using a mixture of Eu^III/Tb^IIIsalts as starting material, color-tunable coordination polymers have been obtained of which the emission color can be changed from red to green with different Eu^III/Tb^IIIratios.

Full text of DOI:10.1016/j.poly.2016.10.050

Accepted Manuscript
Synthesis, structure and photoluminescence properties of lanthanoid coordina-
tion polymers based on tetra(3,5-dicarboxyphenoxymethyl)methane
Xue Liu, Maxime A. Siegler, Michiel Hilbers, Elisabeth Bouwman
PII:
S0277-5387(16)30547-2
DOI:
http://dx.doi.org/10.1016/j.poly.2016.10.050
POLY 12303
Reference:
Polyhedron
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Accepted Date:
26 September 2016
31 October 2016
Please cite this article as: X. Liu, M.A. Siegler, M. Hilbers, E. Bouwman, Synthesis, structure and photoluminescence
properties of lanthanoid coordination polymers based on tetra(3,5-dicarboxyphenoxymethyl)methane,
Polyhedron (2016), doi: http://dx.doi.org/10.1016/j.poly.2016.10.050
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Synthesis, structure and photoluminescence properties of lanthanoid coordination
polymers based on tetra(3,5-dicarboxyphenoxymethyl)methane
Xue Liu,a Maxime A. Siegler,b Michiel Hilbers,c Elisabeth Bouwman*a
a) Leiden Institute of Chemistry, Gorlaeus Laboratories Leiden University, P.O. Box 9502, Leiden, 2300 RA (The
Netherlands) E-mail: bouwman@chem.leidenuniv.nl
b) Small Molecule X-ray Facility, Department of Chemistry Johns Hopkins University, Baltimore, MD 21218 (USA)
c) van 't Hof Institute for Molecular Sciences, University of Amsterdam, The Netherlands
Abstract
A series of isostructural lanthanoid coordination polymers with the formula [Ln2(H6L)(H4L)(H2O)2]n (XL-
Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII; H8L = tetra(3,5-dicarboxyphenoxymethyl)methane) has been
synthesized. The compounds (except XL-Gd) exhibit the characteristic emission of trivalent lanthanoid
ions under UV irradiation. By using a mixture of EuIII/TbIII salts as starting material, color-tunable
coordination polymers have been obtained of which the emission color can be changed from red to green
with different EuIII/TbIII ratios.
Keywords: Coordination Polymers; Luminescence; Lanthanoids; Hydrothermal; Topology
Introduction
In recent years, luminescent lanthanoid coordination polymers (Ln-CPs) have attracted extensive research
efforts due to their unique luminescence properties, such as long lifetime, high quantum yields, and
characteristic sharp line emissions [1]. By rational selection of the organic and inorganic components, Ln-
CPs can generate intense photoluminescence via the antenna effect [2-5]. Due to the similar chemical
properties of the different lanthanoid metal ions, it is possible to synthesize coordination polymers with
more than one kind of lanthanoid ions occupying the identical sites in the crystal structures [6-8]. By this
strategy, multi-color emitting CPs have been obtained, which have been demonstrated to be potentially
useful in applications such as ratiometric thermometers, ratiometric sensors of small organic molecules
and ions, luminescence barcodes and white-light emitting phosphors [9-24].
Continuing our previous efforts in this field of research, we synthesized a series of new Ln-CPs using the
potentially cross-linking ligand tetra(3,5-dicarboxyphenoxymethyl)methane (H8L) shown in Figure 1. By
using mixed Eu/Tb salts as starting material mixed Ln-CPs were obtained. The emission color of these
1

mixed Ln-CPs can be tuned from red to green under single-wavelength excitation by adjusting the Eu/Tb
molar ratio.
Experimental Section
General
The ligand tetra(3,5-dicarboxyphenoxymethyl)methane was synthesized following literature procedures
[25, 26]. All chemicals and solvents are commercially available and were used without further purification.
Elemental analysis for C and H was performed at the Microanalytical laboratory Kolbe in Germany. IR
spectra were recorded on a Perkin Elmer UATR Two FT-IR spectrometer set to a resolution of 4 cm–1.
The excitation and emission spectra were recorded on a Shimadzu RF-5301PC spectrofluoriphotometer.
X-ray powder diffraction patterns were recorded on a Philips PW 1050 diffractometer using Cu Kα
radiation (λ = 1.54178 Ǻ). Inductively coupled plasma optical emission spectrometry (ICP-OES) was
measured on a VISTA-MPX Simultaneous ICP-OES with Varian SPS 3 sample preparation system.
Thermogravimetric analyses (TGA) spectra were recorded on a NETZSCH STA 499 instrument under
argon atmosphere with heating rate of 3 °C per minute. The fluorescence lifetime was measured using a
Hamamatsu R928P photomultiplier connected to a Tektronix DPO4054 digital scope, a Carl Zeiss M20
grating monochromator was used to select the emission wavelength. A Labview program was used to
collect and to average the data. Excitation was done with an Ekspla NTB342B Nd:YAG laser equipped
with a OPO and SHG to generate 5ns pulses at a 10 Hz rate.
Synthesis of the Ligand (H8L)
The ligand was synthesized via a slightly modified procedure from literature [25]. To a solution of
dimethyl-5-hydroxyisophthalate (9.2 g, 44 mmol) and K2CO3 (16.6 g, 120 mmol) in DMF (50 ml),
pentaerythrityl tetrabromide (3.87g, 10.0 mmol) was added slowly. The solution was stirred at room
temperature for 20 min, then heated up to 100 °C for 72 h. The reaction was then cooled to room
temperature, all the solvent was evaporated. The resulting white residue was added to a solution of KOH
(10.24 g, 80 mmol) in a water/ethanol mixture (50 ml/50 ml) and refluxed for 6 h. The reaction mixture
was cooled down to room temperature, and concentrated HCl was added until pH=1. The resulting white
1
precipitate was filtered and dried in vacuo. Yield 6.0 g, 91%. H NMR (300 MHz, DMSO): δ =8.06 (s,
13
4H), 7.72 (s, 8H), 4.50 (s, 8H) ppm. C NMR (75 MHz, DMSO): δ = 166.8, 159.1, 133.1, 123.1, 119.8,
66.9, 45.2 ppm. IR (v): 3083 (br), 2626 (br), 1690 (vs), 1594 (s), 1459 (m), 1413 (m), 1327 (m), 1211 (s),
1123 (m), 1041 (m), 998 (w), 904 (w), 882 (w), 759 (s), 726 (s), 489 (w) cm–1.
2

Synthesis of [Ln2(H6L)(H4L)(H2O)2]n (XL-Ln; Ln = Sm, Eu, Gd, Tb, Dy) and the Mixed Lanthanoid
Compounds XL-EuxTb1-x (x = 0.2, 0.4, 0.6, 0.8).
The ligand H8L (21 mg, 26.5 mmol) was mixed with TbCl3•6H2O (20 mg, 53 mmol) in 10 ml H2O and the
reaction mixture was transferred to a 20 ml Teflon-lined stainless-steel vessel, which was heated to 170 °C
for 3 days. Then the vessel was cooled down to room temperature at a rate of 20 °C per hour. The
colorless flat crystals were collected by filtration and dried in vacuo. Yield: 6 mg (24 %, based on ligand).
XL-Tb. Elemental analysis found (calc) for C37H27O21Tb: C, 45.78 (45.98); H, 2.92 (2.82). Selected IR
data (v, cm–1): 2929 (br), 2528 (br), 1643 (vs), 1598 (m), 1541 (m), 1447 (m), 1377 (s), 1263 (s), 1209 (m),
1133 (m), 1043 (m), 906 (m), 754 (vs), 679 (m), 663 (m), 596 (w), 555 (w), 508 (w).
XL-Ln (Ln = Sm, Eu, Gd, Dy) and the mixed lanthanoid compounds were made following a similar
procedure, but using Sm, Eu, Gd, Dy salts or a mixture of Eu and Tb salts. ICP-OES was used to
determine the Eu/Tb molar ratio in the final products.
XL-Sm. Selected IR data (v, cm–1): 2923 (br), 2520 (br), 1642 (vs), 1599 (m), 1536 (m), 1433 (m), 1374
(s), 1256 (s), 1208 (m), 1136 (m), 1029 (m), 906 (m), 754 (vs), 655 (m), 595 (w), 552 (w), 508 (w).
XL-Eu. Selected IR data (v, cm–1): 2934 (br), 2535 (br), 1642 (vs), 1590 (m), 1540 (m), 1431 (m), 1374
(s), 1261 (s), 1212 (m), 1137 (m), 1029 (m), 905 (m), 754 (vs), 677 (m), 595 (w), 508 (w).
XL-Gd. Selected IR data (v, cm–1): 2933 (br), 2553 (br), 1643 (vs), 1596 (m), 1538 (m), 1443 (m), 1375
(s), 1260 (s), 1211 (m), 1131 (m), 1030 (m), 906 (m), 754 (vs), 677 (m), 664 (m), 596 (w), 506 (w).
XL-Dy. Selected IR data (v, cm–1): 2929 (br), 2524 (br), 1644 (vs), 1600 (m), 1543 (m), 1450 (m), 1376
(s), 1263 (s), 1203 (m), 1134 (m), 1043 (m), 905 (m), 755 (vs), 683 (m), 656 (m), 596 (w), 509 (w).
XL-Eu0.2Tb0.8 analyzed as [Eu0.66Tb1.34(H6L)(H4L)(H2O)2]n. Selected IR data (v, cm–1): 2929 (br), 2517 (br),
1641 (s), 1600 (m), 1543 (m), 1450 (m), 1433 (m), 1375 (s), 1256 (s), 1198 (m), 1134 (m), 1031 (m), 906
(m), 877 (w), 800 (w), 754 (vs), 677 (m), 655 (m), 595 (w), 552 (w), 506 (w).
XL-Eu0.4Tb0.6 analyzed as [Eu1.10Tb0.90(H6L)(H4L)(H2O)2]n. Selected IR data (v, cm–1): 3073 (br), 2529 (br),
1643 (s), 1601 (m), 1544 (m), 1455 (m), 1433 (m), 1377 (s), 1264 (s), 1211 (m), 1135 (m), 1043 (m), 906
(m), 875 (w), 799 (w), 756 (vs), 679 (m), 595 (w), 553 (w), 507 (w).
XL-Eu0.6Tb0.4 analyzed as [Eu1.44Tb0.56(H6L)(H4L)(H2O)2]n. Selected IR data (v, cm–1): 2929 (br), 2526 (br),
1642 (s), 1599 (m), 1539 (m), 1448 (m), 1436 (m), 1375 (s), 1256 (s), 1207 (m), 1133 (m), 1031 (m), 905
(m), 876 (w), 801 (w), 754 (vs), 681 (m), 656 (m), 595 (w), 553 (w), 508 (w).
XL-Eu0.8Tb0.2 analyzed as [Eu1.74Tb0.26(H6L)(H4L)(H2O)2]n. Selected IR data (v, cm–1): 2934 (br), 2535 (br),
1645 (s), 1599 (m), 1544 (m), 1453 (m), 1433 (m), 1376 (s), 1264 (s), 1213 (m), 1135 (m), 1046 (m), 906
(m), 877 (w), 798 (w), 756 (vs), 678 (m), 664 (m), 595 (w), 552 (w), 509 (w).
3

Single Crystal X-ray Crystallography
All reflection intensities were measured at 110(2) K using a SuperNova diffractometer (equipped with
Atlas detector) with Cu Kα radiation (λ = 1.54178 Å) under the program CrysAlisPro (Version
1.171.36.32 Agilent Technologies, 2013). The same program was used to refine the cell dimensions and
for data reduction. The structure was solved with the program SHELXS-2014/7 and was refined on F2
with SHELXL-2014/7 [27]. Analytical numeric absorption correction based on a multifaceted crystal
model was applied using CrysAlisPro. The temperature of the data collection was controlled using the
system Cryojet (manufactured by Oxford Instruments). The H atoms were placed at calculated positions
(unless otherwise specified) using the instructions AFIX 23, AFIX 43 or AFIX 147 with isotropic
displacement parameters having values 1.2 or 1.5 Ueq of the attached C or O atoms. The H atoms attached
to O1W (coordinated water molecule) were found from difference Fourier maps, and their coordinates
were refined freely. The O−H and H…H bond distances for the coordinated water molecule were
restrained using the DFIX instructions. The structure is ordered. The organic moiety has twofold axial
symmetry as C101 and C103 are located at sites of twofold axial symmetry.
Additional notes: (i) the displacement ellipsoids for atoms O53 and O54 are somewhat elongated, most
likely suggesting slight disorder. An attempt to model the disorder was not successful as the refinement
was not stable. Thus, both atoms were left ordered in the final refinement.
(ii) There is one residual electron density Q peak of 0.54 e– Å–3 found at 0.96 Å from O23. This peak
cannot be an H atom because it is not located within the plane defined by C73, O13 and O23, and because
there are no potential O acceptors around O23 except for O11.
Results and discussion
Description of the Structure
The structure of XL-Tb was determined by single crystal X-ray crystallography and was shown to have
the formula [Tb2(H6L)(H4L)(H2O)2]n; all compounds proved to be isostructural as deduced from powder
XRD (discussed below). X-ray quality single crystals of XL-Tb were obtained from the hydrothermal
synthesis [28]. XL-Tb crystallized in the monoclinic space group P2/c (Table S1); the asymmetric unit
contains two half parts of two ligands with different coordination modes, one terbium ion and one
coordinated water molecule (Figure 1a and Figure S1). The TbIII ion is coordinated by seven O atoms from
six carboxylate groups and one O atom from water, forming a geometry best described as a distorted
bicapped trigonal prism. There are no O atoms shared by TbIII ions. The Tb-O bond lengths are found in
the range of 2.254(2) – 2.582(2) Å, which can be considered normal for this type of bonds (Table S2) [9,
14, 16, 29, 30]. The ligands show two different kinds of coordination modes. In the first coordination
mode the ligand is twice deprotonated and coordinated to six different TbIII ions (Figure 1c). In the second
4

coordination mode the ligand is four times deprotonated and coordinated to four different TbIII ions
(Figure 1d). In both cases the ligand has twofold rotational symmetry with the axis passing through the
central carbon atom of the ligand. Hydrogen bonds can be found in the crystal structure which may
enhance the structure stability (Table S2). The structure is tightly packed and does not contain any
solvent-accessible voids.
Figure 1. Impression of the crystal structure of [Tb2(H6L)(H4L)(H2O)2]n and coordination modes of the ligand. a) asymmetric unit;
b) Projection of the structure of XL-Tb along the c axis; c) coordination mode of the ligand H6L; d) coordination mode of the
ligand H4L. Green = terbium, red = oxygen, grey = carbon, hydrogen is omitted for clarity.
Topology Studies
The free software programme TOPOS was used to analyze the structure [31-33]. The ligand is coordinated
to either six TbIII or four TbIII ions, and thus are considered as a six or four connected nodes (Figure 2a and
2b). Each TbIII ion is bound by five different ligands and thus treated as a five-connected node (Figure 2c).
Due to the absence of bridging O atoms, the coordination polyhedra of the metal ions share neither an
edge nor a point. Thus, the use of SBUs is not suitable in this structure analysis and in the topology
5

structure analysis only the coordination polyhedron itself is treated as a node. The point symbol of this
topology is {44•62}{46•64}2{48•67} (Figure 2d).
Figure 2. Topological structure of XL-Tb. a) the six-connected node (ligand H6L2–); b) the four-connected node (ligand H4L4–); c)
the five-connected node (TbIII); d) topology structure. (Gray node = TbIII; yellow node = six connected ligand; blue node = four
connected ligand)
Powder XRD and IR Spectroscopic Studies
Powder XRD was used to confirm the phase purity of XL-Ln (Ln = Sm, Eu, Gd, Tb and Dy) and the
mixed-lanthanoid samples. As shown in Figures S2 and S3, the PXRD pattern of all samples are highly
similar to the simulated pattern from the single crystal structure of XL-Tb, confirming the phase purity of
all samples and their being isomorphous. The highly similar IR spectra further confirm that all the
compounds are isostructural (Figure S4 and S5).
Luminescent Properties
When illuminated with a laboratory high-pressure Hg lamp (366 nm), the compounds XL-Sm, XL-Eu,
XL-Tb and XL-Dy show orange, red, green and white luminescence, respectively, whereas XL-Gd shows
6

no luminescence emission at room temperature. Solid-state photoluminescence spectra for all compounds
are shown in Figure 3. The CIE (Commission Internationale de l’Éclairage) coordinates have been
calculated on the basis of the emission spectra; the emission colors of all four compounds are depicted in
the CIE chromaticity diagram shown in Figure 4.
Figure 3. The excitation and emission spectra of a) XL-Sm; b) XL-Eu; c) XL-Tb; d) XL-Dy.
The emission spectrum of XL-Sm contains the four characteristic peaks for the SmIII ion at 562, 598, 644
4
6
and 713 nm, which are ascribed to the G5/2→ HJ transitions (J = 5/2, 7/2, 9/2 and 11/2) [34-36]. The
4
6
dominant orange color of emission is due to the most intense peak of the G5/2→ H9/2 transition. The
6
4G5/2→ H5/2 transition is magnetic dipole (MD) in nature and its intensity is less sensitive to the
4
6
coordination environment of the SmIII ion. As a comparison, the G5/2→ H9/2 transition is electric dipole
(ED) in nature, and its emission intensity is more sensitive to the coordination environment [37-39]. The
6
4
6
fact that the 4G5/2→ H9/2 transition is more intense than the G5/2→ H5/2 transition indicates that the SmIII
7

ion occupies a non-centrosymmetric site [34, 40, 41], which is in agreement with the single crystal
structure. When excited by 330 nm UV light, the compound XL-Eu exhibits the four typical peaks of the
5
7
EuIII ion at 585, 615, 649 and 702 nm, assigned to the D0→ FJ transitions (J = 1–4). The emission
5
7
spectrum is dominated by the D0→ F2 transition. The compound XL-Tb displays the characteristic
5
7
emission peaks of TbIII at 486, 542, 587 and 622 nm, related to the D4→ FJ (J = 6–3) transitions upon
excitation with 333 nm light [21, 22]. The emission spectrum of XL-Dy comprises three peaks at 485, 574
6
and 660 nm, corresponding to the transitions of 4F9/2→ HJ (J = 15/2, 13/2 and 11/2) of the DyIII ion [16].
Figure 4. The luminescence colors of XL-Sm, XL-Eu, XL-Tb and XL-Dy in a CIE chromaticity diagram. CIE coordinates: XL-
Sm (X = 0.4332, Y = 0.2945); XL-Eu (X = 0.5691, Y = 0.3134); XL-Tb (X = 0.3189, Y = 0.6000); XL-Dy (X = 0.3662, Y =
0.3788).
The lowest singlet excited state of the ligand is 32260 cm−1 as estimated from the room temperature solid-
state absorption spectrum of XL-Gd (Figure S6; 310 nm). The energy level of the triplet excited state of
the ligand H8L is 23200 cm−1 (431 nm), as estimated from the phosphorescence spectrum of XL-Gd at 77
K (Figure S7). The energy gap between the singlet and triplet excitation states of ligand thus is calculated
to be 9060 cm−1, which is suitable for efficient intersystem crossing according to Reinhoudt’s rules [42].
Due to the small energy gaps between the emitting level and highest energy levels of the ground state of
the SmIII and DyIII ions, their emission is easily quenched by non-radiative processes [43]. For XL-Tb and
XL-Eu, the energy differences between the triplet state of the ligand and the LnIII emitting level (for TbIII,
5
5D4, 20.5 × 103 cm−1; for EuIII, D0, 17.2 × 103 cm−1) are 2700 cm−1 and 6000 cm−1, respectively. This
8

suitable energy gap makes the energy transfer from the ligand triplet state to these LnIII exited states
efficient and without significant back transfer [6, 43, 44].
Figure 5. The decay curves of a) XL-Sm; b) XL-Eu; c) XL-Tb; d) XL-Dy. (λex=325 nm; XL-Sm, monitored at 644 nm, τ=0.719 µs;
XL-Eu, monitored at 615 nm, τ=0.363 ms; XL-Tb, monitored at 542 nm, τ=0.814 ms; XL-Dy, monitored at 574 nm, τ= 8.431 µs)
The emission lifetimes of the compounds XL-Sm, XL-Eu, XL-Tb and XL-Dy were recorded (Figure 5).
The decay curves of all four compounds show monoexponential behavior, in agreement with the LnIII
emitting centers sharing identical coordination environments in the compounds. The lifetimes of the
compounds XL-Ln (Ln = Sm, Eu, Tb and Dy) are 0.719 µs, 0.363 ms, 0.814 ms and 8.431 µs, which are
normal values compared to the reported values of Ln compounds [11, 21, 41].
9

Figure 6. The emission spectra of XL-EuxTb1–x (x = 0.2, 0.4, 0.6, 0.8) (λexc = 335 nm).
The luminescence emission spectra of the lanthanoid coordination polymer can be tuned by changing the
molar ratio of Eu/Tb ions present in the compound (Figure 6). The Eu:Tb ratio was varied from 2:8 to 8:2;
a CIE diagram showing the emission colors of the resulting compounds is displayed in Figure 7. With
increasing Eu:Tb ratio, the emission color of the mixed-lanthanoid compound changes from green to red.
Furthermore, the lifetime of TbIII emission monitored at 544 nm (5D4) decreases, indicating the occurrence
of energy transfer from TbIII to EuIII, and confirming the compounds to be truly heterometallic and not just
a physical mixture of two compounds. The energy-transfer efficiency from the TbIII exited state to EuIII in
the mixed-lanthanoid sample is calculated with η = 1−τ/τ0, where τ0 and τ are the lifetime of the TbIII
emission in XL-Tb and the mixed-lanthanoid compounds, respectively. The results are presented in table
S3. The energy-transfer efficiency increases from 0.072 to 0.303 with increasing EuIII concentrations.
Compared to our previous work, the energy transfer from TbIII to EuIII is less efficient in this series of
material due to the longer Ln-Ln distances (for this work, Ln-Ln = 6.898 Å; four our previous work, Ln-
Ln = 4.212 Å and 4.532 Å) [22].
10

Figure 7. CIE diagram showing the luminescence colors of XL-Tb, XL-Eu and XL-EuxTb1–x (x = 0.2, 0.4, 0.6, 0.8). CIE
coordinates: XL-Eu0.2Tb0.8 (X = 0.371, Y = 0.563); XL-Eu0.4Tb0.6 (X = 0.424, Y = 0.516); XL-Eu0.6Tb0.4 (X = 0.0.532, Y = 0.381);
XL-Eu0.8Tb0.2 (X = 0.569, Y = 0.313).
Conclusions
For the first time, lanthanoid coordination polymers have been prepared using the inherently crosslinking
ligand tetra(3,5-dicarboxyphenoxymethyl)methane and the compounds were fully characterized. The
studies revealed that XL-Sm, XL-Eu, XL-Tb and XL-Dy exhibit the typical luminescent emission of the
trivalent lanthanoid ions under UV irradiation. Tunable red-to-green emission is achieved by using a
mixture of Eu/Tb salts as starting material in the hydrothermal synthesis of the coordination polymer.
These multicolor emission materials are potentially useful for ratiometric sensors, optoelectronic devices
and labeling applications [9].
Acknowledgements
X. Liu gratefully acknowledges a grant from the Chinese Scholarship Council (no. 201206250014). We
are grateful to Dr. Hong Zhang (University of Amsterdam) for lifetime measurements and Mr. Jos van
Brussel (Leiden University) for ICP analysis.
Appendix A. Supplementary data
CCDC 1422060 contains the supplementary crystallographic data for the compound. These data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
11

Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-
336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Spectroscopic details in the supplementary data include: Powder XRD pattern of XL-Sm, XL-Eu, XL-Gd,
XL-Tb and XL-Dy and the simulated pattern from the single crystal structure of XL-Tb. Powder XRD
patterns of XL-EuxTb1-x (x = 0.2, 0.4, 0.6, 0.8). FTIR spectra of XL-Sm, XL-Eu, XL-Gd, XL-Tb and XL-
Dy. FTIR spectra of XL-EuxTb1–x (x = 0.2, 0.4, 0.6, 0.8). Solid-state absorption spectrum of XL-Gd.
Phosphorescence spectrum of XL-Gd at 77 K and its deconvolution with Gaussians.
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Synthesis, structure and photoluminescence properties of lanthanoid coordination polymers
based on tetra(3,5-dicarboxyphenoxymethyl)methane
Xue Liu,a Maxime A. Siegler,b Michiel Hilbers,c Elisabeth Bouwman*a
Graphical abstract
A series of isostructural lanthanoid coordination polymers with the ligand tetra(3,5-
dicarboxyphenoxymethyl)methane) has been synthesized and characterized. The emission colors
of coordination polymers can be tuned by using a mixture of EuIII/TbIII salts.
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