Halogen bonding interactions assisted network expansion of a tetrahedral cobalt phosphonate coordination polymer bearing 4,4′-bipyridine ligand

Article abstract of DOI:10.1016/j.molstruc.2020.129063

A new cobalt phosphonate coordination polymer {[Co₂(BrBzPO₃)₂(bpy)]?2H₂O}_n (1) has been synthesized from the reactions of Co(NO₃)₂, 2-bromobenzyl phosphonic acid (BrBzP(O)(OH)₂), and 4,4′-bipyridine (bpy) via reactants slow diffusion in H₂O/ethanol solvent media at 60°C. Single-crystal X-ray diffraction analysis reveals that the Co(II) center has a {CoO₃N} tetrahedral geometry. The coordinative network of 1 shows a layer structure constructed from Co–BrBzPO₃ chains, which contain four-membered rings assembled from vertex-sharing {CoO₃N} and {CPO₃} tetrahedral units, connected by bpy linkers. It is worthy to note that net-to-net Br–Br halogen bonding interactions play the key supramolecular interactions to significantly dominate network expansion from a two-dimensional (3,4)-connected coordinative layer with a point symbol of (4²6)(4²6³8) to a three-dimensional (4,4)-connected supramolecular network having a point symbol of (4²6³8)(4²6³8). Further, there are multiple noncovalent supramolecular interactions involving strong O–H???O and weak C–H???Br and C–H???π interactions that provide powerful supports for stabilizing the whole crystal structure. Thermogravimetric (TG) analysis indicates that the coordinative network of 1 is high thermally stable upon heating to 340°C.

Full text of DOI:10.1016/j.molstruc.2020.129063

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Halogen bonding interactions assisted network expansion of a
tetrahedral cobalt phosphonate coordination polymer bearing
4,40-bipyridine ligand
Jing-Yun Wu , Zhi-Jia Hu , Hui-Ling Sung
PII:
S0022-2860(20)31386-7
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MOLSTR 129063
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10 August 2020
Please cite this article as: Jing-Yun Wu , Zhi-Jia Hu , Hui-Ling Sung , Halogen bond-
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Highlights
 Halogen bonding interactions assisted network expansion of a tetrahedral cobalt phosphonate
coordination polymer bearing 4,4′-bipyridine ligand from a coordinative layer to a
three-dimensional supramolecular network is reported.

Halogen bonding interactions assisted network expansion of a tetrahedral cobalt
phosphonate coordination polymer bearing 4,4′-bipyridine ligand
Jing-Yun Wu,a Zhi-Jia Hua and Hui-Ling Sungb,*
a Department of Applied Chemistry, National Chi Nan University, Nantou County 545, Taiwan
b Division of Preparatory Programs for Overseas Chinese Students, National Taiwan Normal
University, New Taipei City 244, Taiwan
*Corresponding Author.
E-mail address: hlsung@ntnu.edu.tw (H.-L. Sung)

Abstract
A new cobalt phosphonate coordination polymer {[Co2(BrBzPO3)2(bpy)]∙2H2O}n (1) has been
synthesized from the reactions of Co(NO3)2, 2-bromobenzyl phosphonic acid (BrBzP(O)(OH)2), and
4,4′-bipyridine (bpy) via reactants slow diffusion in H2O/ethanol solvent media at 60 °C.
Single-crystal X-ray diffraction analysis reveals that the Co(II) center has a {CoO3N} tetrahedral
geometry. The coordinative network of 1 shows a layer structure constructed from Co–BrBzPO3
chains, which contain four-membered rings assembled from vertex-sharing {CoO3N} and {CPO3}
tetrahedral units, connected by bpy linkers. It is worthy to note that net-to-net Br–Br halogen
bonding interactions play the key supramolecular interactions to significantly dominate network
expansion from a two-dimensional (3,4)-connected coordinative layer with a point symbol of
(426)(42638) to a three-dimensional (4,4)-connected supramolecular network having a point symbol
of (42638)(42638). Further, there are multiple noncovalent supramolecular interactions involving
strong O–H∙∙∙O and weak C–H∙∙∙Br and C–H∙∙∙π interactions that provide powerful supports for
stabilizing the whole crystal structure. Thermogravimetric (TG) analysis indicates that the
coordinative network of 1 is high thermally stable upon heating to 340 °C.
Keywords: cobalt; C–H∙∙∙π interaction; coordination polymer; halogen bonding interaction;
phosphonate
Introduction
Metal phosphonate complexes possessing discrete and extended structures have been very well
studied for a long period of time due to not only the diversities of structures [1,2] but also their
multidisciplinary applications in proton conductivity [3–6], adsorption and separation [7,8],
magnetism [9–11], ion exchange [12,13], and catalysis [3,14,15] etc. As multidentate O donor
ligands, phosphonate family, [RPO3]2−, [RP(OH)O2]−, and related members, have multisite

coordination behavior and the ability to bind multiple metal center, as a result, representing a high
number of possible metal-binding modes [1,16,17]. Therefore, it is of particular important to
rationally design novel metal phosphonate complexes with an intriguing diversity of structures and
properties [8,18–20].
On the other hand, noncovalent interactions, especially hydrogen bonding (HB), have emerged
structure-defining capability to control aggregation of organic molecules from the directed assembly
through numerous recognition patterns, called supramolecular synthons [21–23]. Further, hydrogen
bonding (HB) also plays an important role in stabilizing supramolecular aggregates. In parallel, with
regarded to directionality and strength, halogen bonding (XB) is a strong, specific, and directional
noncovalent interaction that involves halogen atoms acting as electron acceptor to provide an
alternative entry in the fields of crystal engineering and supramolecular chemistry [24–26]. So far,
numerous crystal-engineered supramolecular assemblies in organic supramolecular system have been
fabricated by halogen bonding, demonstrating remarkable effectiveness and reliability of such
interactions [24,26–28]. However, halogen bonding is arguably the least exploited in inorganic
supramolecular system [29–35], especially as a key force in forming extended networks, that is
mainly featured by metal-ion coordination and further by hydrogen bonding.
In spired by the aforementioned facts, in this present work, a new bromo-functionalized
phosphonate ligand, namely 2-bromobenzyl phosphonic acid (BrBzP(O)(OH)2), has been designed
and then utilized to construct a tetrahedral cobalt phosphonate coordination polymer bearing
ancillary 4,4′-bipyridine (bpy) ligands, which has a two-dimensional layer structure. Noteworthy,
under control of Br–Br halogen bonding, a three-dimensional supramolecular network is formed.
This work demonstrates a rare case that recognition patterns of halogen bonding rather than
hydrogen bonding being the key supramolecular synthon to significantly expand network in
coordination polymers.

2. Experimental
2.1. Materials and instruments
1
All chemicals were purchased commercially and used as received without further purification. H
NMR spectra were recorded using a Bruker AMX-300 Solution-NMR spectrometer. Chemical shifts
are reported in parts per million (ppm) with reference to the residual protons of the deuterated
solvent, and coupling constants are reported in hertz (Hz). Mass spectra were recorded using a
Bruker Daltonics flexAnalysis matrix-assisted laser desorption/ionization time of flight
(MALDI-TOF) mass spectrometer. Thermogravimetric analyses were performed using a Thermo
Cahn VersaTherm HS TG analyzer from room temperature to 900 °C with a heating rate of 5 °C
min–1 under a flux of nitrogen. Infrared (IR) spectra were recorded using a Perkin-Elmer Frontier
FT-IR spectrometer in the region of 4000–500 cm–1; abbreviations: s = strong, m = medium, w =
weak, vw = very weak. Powder X-ray diffraction patterns (PXRD) were measured using a Shimadzu
XRD-7000 diffractometer with a graphite monochromatized Cu K radiation ( = 1.5406 Å) at 40
kV and 30 mA with a step size of 0.02° in θ and a scan speed of 1 s per step size. Microanalyses
were carried out using a Perkin-Elmer 2400 CHN elemental analyzer.
2.2. Synthesis of 2-bromobenzyl phosphonic acid (BrBzP(O)(OH)2)
In a three neck, round-bottomed flask, 2-bromobenzyl bromide (10.0 g, 0.040 mol) was added, and
the flask was alternately vacuumed and purged argon atmosphere three times. Then triethyl
phosphite (P(OEt)3, 15 mL, 0.089 mol) was added. The reaction mixture was refluxed under stirring
in an argon atmosphere at 140 °C for 24 h. After cooling to room temperature, conc. HCl (150 mL)
was added. The reaction mixture was refluxed again under stirring in an argon atmosphere at 110 °C
for 48 h. After the reaction mixture was cooled to room temperature, the reaction solvent was
subsequently was removed in vacuum. The crude product was purified with ethyl ether to give pure
2-bromobenzyl phosphonic acid (BrBzP(O)(OH)2) as white solids in 95% yield (9.6 g, 0.038 mmol).

1H NMR (DMSO-d6, ppm): δ 7.56 (d, J = 9.0 Hz, 1H), 7.44 (d, J = 9.0 Hz, 1H), 7.31 (t, J = 9.0 Hz,
1H), 7.13 (t, J = 9.0 Hz, 1H), 3.16 (d, J = 24.0 Hz, 2H). MS (MALDI-TOF): m/z 251.189 [M+H]+
(250.947 for C7H9(79Br)O3P). IR (ATR, cm–1): 1564(vw), 1472(w), 1439(w), 1399(vw), 1267(m),
1180(s), 1029(s), 962(m), 830(w), 777(m), 737(m), 659(vw), 599(vw), 533(m). Anal. Calcd for
C7H8BrO3P: C, 33.49; H, 3.21%. Found: C, 33.70; H, 3.11%.
2.3. Synthesis of {[Co2(BrBzPO3)2(bpy)]∙2H2O}n (1)
In a glass tube, a solution of BrBzP(O)(OH)2 (6.3 mg, 0.025 mmol) and 4,4′-bipyridine (bpy, 7.8 mg,
0.050 mmol) in H2O/EtOH (3 mL, v:v = 1:1) was set as the bottom layer, which was layered by a
solution of Co(NO3)2 (27.4 mg, 0.15 mmol ) in H2O/EtOH (1 mL, v:v = 1:1) on top. The tube was
sealed and then allowed to stay in an oven at 60 °C for one day. Blue-colored needle-like crystals
were collected in a yield of 36% based on BrBzP(O)(OH)2 (6.9 mg, 0.0092 mmol). Elemental Anal.
Calcd. for C24H24Br2Co2N2O8P2: C, 35.67; H, 2.99; N, 3.47%. Found: C, 35.35; H, 3.03; N, 3.51%.
IR (ATR, cm–1): 3498(w), 3098(vw), 3075(vw), 3045(vw), 3011(vw), 1610(m), 1535(w), 1495(w),
1472(m), 1423(m), 1320(w), 1289(w), 1238(w), 1151(w), 1117(m), 1069(s), 999(s), 815(m), 780(m),
747(w), 715(w), 614(m), 555(m).
2.4. Crystallography
Single-crystal X-ray diffraction data were collected at 200(2) K using a Bruker D8 Venture
diffractometer configured with a PHOTO100 CMOS detector. The radiation used was a graphite
monochromated Mo K radiation ( = 0.71073 Å). The crystal structure was solved by direct
methods with the SIR92 program [36] and refined against F2 by the full-matrix least-squares
technique, using the SHELXL-2014/7 [37], incorporated in WINGX program package [38].
Non-hydrogen atoms were positioned from the different Fourier maps and refined anisotropically.
Carbon-bound hydrogen atoms were positioned by geometrical calculation and refined as a riding

model. Oxygen-bound hydrogen atoms were first located on difference Fourier maps, and then fixed
at the calculated positions and were included in the final refinement. All hydrogen atoms were
refined isotropically. Crystallographic data are summarized in Table 1. Selected bond lengths and
angles are listed in Table 2 and hydrogen bond distances and angles are listed in Table 3.
Table 1
Crystal data and structure refinement for 1
Chemical formula
Formula weight
Crystal system
Space group
Temperature
a (Å)
C24H24Br2Co2N2O8P2
808.07
Triclinic
̅
P1
200(2) K
5.3297(6)
11.3283(13)
12.0278(16)
101.715(4)
98.669(4)
100.137(3)
686.75(14)
1
b (Å)
c (Å)
 (°)
 (°)
 (°)
V (Å3)
Z
Dcalcd (g cm–3)
F (000)
1.954
400
Goodness-of-fit (GOF) on F2
1.057
0.0293, 0.0569
R1, wR2 [I > 2σ(I)]a
R1, wR2 (all data)a
0.0480, 0.0655
2
2 2 1/2
a R1 = Σ||F0|－|Fc||／Σ|F0|；wR2 = [Σw(F0 －Fc2)2／Σw(F0 ) ]
3. Results and Discussion
3.1 Crystal structure of 1
̅
Single-crystal X-ray diffraction analysis revealed that 1 crystallized in the triclinic space group P1
and its asymmetric unit contains one Co(II) center, one BrBzPO32– dianion, one-half bpy ligand, and
2–
one lattice water molecule. The dianionic phosphonate, BrBzPO3 , obtained by fully deprotonation
of BrBzP(O)(OH)2, bridges three Co(II) centers through each of the three potential coordinating
oxygen atoms (Fig. 1), and thus has a μ3,η1:η1:η1-coordination mode, also termed as [3.111]

according to the Harris coordination notation [39]. The three P–O bond lengths are 1.514(2),
1.516(2), and 1.526(2) Å (Table 2), suggesting high resonance structure among the two P–O– single
bonds and the P=O double bond. There is intra-molecular C–H∙∙∙Br interaction (C∙∙∙Br, 3.238(4) Å,
Table 3) between the methylene (C7) hydrogen and the bromine of the same BrBzPO32– ligand. Bpy,
which could be used as a base, also functions as a bis-monodentate ligand to bridge two Co(II)
centers. In turn, the Co(II) center is surrounded by three oxygen atoms from three different
2–
BrBzPO3 ligands and one nitrogen atom from one bpy ligand, forming a {CoO3N} tetrahedral
geometry (Fig. 1). The Co–O bond lengths range from 1.925(2) to 1.935(3) Å, the Co–N bond length
is 2.049(3) Å, and the O–Co–O/N bond angles range from 101.79(11) to 117.89(11)° (Table 2).
Fig. 1. ORTEP diagram of partial structure of 1 with numbering scheme (symmetry codes: #1, x + 1,
y, z; #2, –x + 1, –y, –z + 1), showing coordination geometry of Co(II) center and coordination modes
of BrBzPO32– dianion and bpy ligand. Displacement ellipsoids are drawn at the 50% probability level.
Lattice water molecule and hydrogen atoms are omitted for clarity.
Table 2
Selected bond lengths (Å) and angles (°) in 1
Co(1)–O(1)
Co(1)–O(3)#2
P(1)–O(1)
1.925(2)
1.935(3)
1.514(2)
Co(1)–O(2)#1
Co(1)–N(1)
P(1)–O(2)
1.934(2)
2.049(3)
1.516(2)
P(1)–O(3)
1.526(2)
O(1)–Co(1)–O(2)#1
O(1)–Co(1)–N(1)
O(2)#1–Co(1)–N(1)
111.77(11)
108.67(11)
101.79(11)
O(1)–Co(1)–O(3)#2
O(2)#1–Co(1)–O(3)#2 110.30(12)
O(3)#2–Co(1)–N(1) 104.94(11)
117.89(11)
Symmetry transformations used to generate equivalent atoms: #1, x + 1, y, z; #2, –x + 1, –y, –z + 1.

Table 3
Hydrogen bonding interactions in 1
D–H∙∙∙A
D–H (Å)
H∙∙∙A (Å)
2.36
2.45
2.73
2.40
D∙∙∙A (Å)
3.079(4)
3.190(4)
3.238(4)
3.294(5)
D–H∙∙∙A (°)
146
149
113
162
O(4)–H(101)∙∙∙O(3)#1
O(4)–H(102)∙∙∙O(3)#2
C(7)–H(7B)∙∙∙Br(1)
C(12)–H(12)∙∙∙O(4)#3
0.82
0.83
0.97
0.93
Symmetry transformations used to generate equivalent atoms: #1, –x, –y, 1 – z; #2, 1 – x, –y, 1 – z;
#3, 1 + x, y, z.
2–
Assembly of Co(II) centers and BrBzPO3 dianions forms a one-dimensional neutral Co–
BrBzPO3 chain structure (Fig. 2a and 2b), which contains four-membered rings assembled from
{CoO3N} tetrahedra and {CPO3} tetrahedra in an alternately vertex-sharing manner. The Co–Co
separations across the O–P–O within the chain are 4.506, 4.606, and 5.330 Å. The Co–BrBzPO3
chains are connected by linear bpy ligands, generating a two-dimensional layer structure (Fig. 2c). If
the Co(II) centers are regarded as 4-connected nodes, the BrBzPO32– dianions as 3-connected nodes,
and the bpy ligands as linear linkers, the two-dimensional layer can be simplified as a binodal
(3,4)-connected net with a point symbol of (426)(42638) in topology (Fig. 2d). The lattice water
molecules sit near the Co–BrBzPO3 chains and being as hydrogen donors make O–H∙∙∙O hydrogen
bonding interactions (O∙∙∙O, 3.079(4) and 3.190(4) Å, Table 3) with two oxygen atoms of two
different BrBzPO32– ligands of the same layer (Fig. 2b). Meanwhile, the lattice water molecules also
act as hydrogen acceptors to form intra-layer C–H∙∙∙O hydrogen bonding interactions (C∙∙∙O, 3.294(5)
Å, Table 3) with the bpy ligands. These findings suggest that lattice water molecules form significant
noncovalent supramolecular interactions with the coordinative network but do not provide the key
interactions to expand network dimension.
(a)
(b)
(c)
(d)

Fig. 2. (a) View of Co–BrBzPO3 chain down the c-axis in 1, showing intra-molecular C–H∙∙∙Br
interactions (dashed lines). (b) Highlight the Co–BrBzPO3 chain viewed down the b-axis in 1,
showing O–H∙∙∙O hydrogen bonding interactions (dashed lines). (c) Representation of
two-dimensional layer structure in 1. Cyan and pink polyhedral units represent the {CoO3N} and
{CPO3} tetrahedral units, respectively. (d) Schematic representation of the two-dimensional
(3,4)-connected net with a point symbol of (426)(42638) in 1.
However, it is of particular note that these layers are stacked well along the crystallographic c axis
(Fig. 3a and 3b), and there are net-to-net supramolecular interactions. The most eye-catching one is
the Br–Br halogen bonding, adopting type I halogen−halogen contact [24,40] with a Br–Br
2–
separation of 3.796 Å, between two closed BrBzPO3 ligands of neighboring layers (Fig. 3c). With
the help of Br–Br halogen bonding interactions, the two-dimensional coordinative layer structure in
1 is expanded to be a three-dimensional supramolecular network which can be simplified as a
binodal (4,4)-connected net having a point symbol of (42638)(42638) in topology (Fig. 3d). In other
words, 1 represents a rare case that halogen bonding interaction rather than hydrogen bonding
interaction dominates the key supramolecular synthon to result in expansion of network dimension in
coordination polymers. Further, inter-layer C–H∙∙∙π interactions (H∙∙∙C, 2.814–3.684 Å) are also
2–
existed between the phenyl rings of the BrBzPO3 ligands and the pyridyl rings of bpy ligands in
any two neighboring layers (Fig. 3c). These weak noncovalent supramolecular interactions
undoubtedly provide supports for stabilizing the whole crystal structure.

(a)
(b)
(c)
(d)
Fig. 3. (a) Ball-and stick and (b) polyhedral representations of Br–Br halogen bonding (dashed lines)
supported three-dimensional supramolecular network viewed down the a-axis in 1. (c) Highlight the
net-to-net Br–Br halogen bonding interactions (green bulk dashed line) and C–H∙∙∙π interactions
(black thin dashed lines) in 1. (d) Schematic representation of the three-dimensional (4,4)-connected
net with a point symbol of (42638)(42638) in 1.
3.2 Thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD) studies
Thermogravimetric (TG) analysis of 1 was performed under flux nitrogen atmosphere from 30 to
900 °C (Fig. 4.). Lattice water molecules were released upon heating to 142–165 °C (found 4.6%;
calcd 4.5%). The coordinative framework remained intact when the temperature was heated to ca.
340 °C, Subsequently, a multistep decomposition process ended at ca. 720 °C was observed. The
final residue of 36.3% was tentatively assigned to CoO (calcd. 37.1%). TG analysis suggests high
thermal stability of 1.

Fig. 4. TG curve of 1.
Phase purity of bulky samples of 1 were confirmed by PXRD measurements using fresh solid
samples at room temperature; the PXRD patterns of 1 were in good agreement with the simulated
patterns calculated from the single-crystal structure data (Fig. 5). The difference in intensities of the
peaks is probably originated from the variation in preferred orientation of the powder samples.
Further, the thermal stability of the crystal structure of 1 was examined. When 1 was thermally
treated at 200 °C for 3 h to completely remove lattice water molecules, the dehydrated 1 was
obtained. The well-drawn PXRD patterns of dehydrated 1 are virtually similar to that of simulated
and as-synthesized 1 (Fig. 5); there are no drastic changes in main patterns and only slight
differences are observed in peak intensity and the appearance of new peaks. The subtle changes can
undoubtedly be attributed to the influence of the escape of lattice water molecules. As a result, the
whole crystal structure of 1 shows high thermal stability that is responsible for the contributions of
multiple noncovalent supramolecular interactions mentioned above, especially the net-forming Br–
Br halogen bonding interactions.

Fig. 5. PXRD patterns of simulated, as-synthesized, and dehydrated 1.
Conclusion
In this work, a tetrahedral cobalt phosphonate coordination polymer 1 bearing ancillary
4,4′-bipyridine ligands showing high thermal stability has been constructed. The coordination layer
structure of 1 contains Co–BrBzPO3 chains involving four-membered rings assembled from
vertex-sharing {CoO3N} and {CPO3} tetrahedral units. Noteworthy, the formation of Br–Br halogen
bonding interactions and C–H∙∙∙π interactions significantly aids the expansion of a coordination layer
structure to be a three-dimensional supramolecular network.
Acknowledgements
We are grateful to National Taiwan Normal University for financial support.
Appendix A. Supplementary data
CCDC 2009094 contains the supplementary crystallographic data for this paper. These data can be
obtained free of charge from the Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.

AUTHOR STATEMENT
All persons who meet authorship criteria are listed as authors, and all authors certify that they have
participated sufficiently in this work, and take public responsibility for the content, including
participation in the concept, experiment design, data analysis, writing as well as revision of the
manuscript.
All authors agree the corresponding author (Hui-Ling Sung) as the representative person for handling
this manuscript.
Declaration of interests
 The authors declare that they have no known competing financial interests or personal
relationships that could have appeared to influence the work reported in this paper.
References
[1]
[2]
[3]
J. Goura, V. Chandrasekhar, Molecular Metal Phosphonates. Chem. Rev. 115 (2015) 6854–
6965.
G.K.H. Shimizu, R. Vaidhyanathan, J.M. Taylor, Phosphonate and sulfonate metal organic
frameworks. Chem. Soc. Rev. 38 (2009) 1430–1449.
R.M.P. Colodrero, M. Bazaga-García, I.R. Salcedo, D. Choquesillo-Lazarte, A. Cabeza, M.V.
Kirillova, A.M. Kirillov, K.D. Demadis, Three-Component Copper-Phosphonate-Auxiliary
Ligand Systems: Proton Conductors and Efficient Catalysts in Mild Oxidative
Functionalization of Cycloalkanes. Inorg. Chem. 57 (2018) 10656–10666.
[4]
M. Bazaga-García, M. Papadaki, R.M.P. Colodrero, P. Olivera-Pastor, E.R. Losilla, B.
Nieto-Ortega, M. .G. Aranda, D. Choquesillo-Lazarte, A. Cabeza, K.D. Demadis, Tuning
Proton Conductivity in Alkali Metal Phosphonocarboxylates by Cation Size-Induced and
Water-Facilitated Proton Transfer Pathways. Chem. Mater. 27 (2015) 424–435.
[5]
[6]
S.S. Bao, N.Z. Li, J.M. Taylor, Y. Shen, H. Kitagawa, L.M. Zheng, Co–Ca Phosphonate
Showing Humidity-Sensitive Single Crystal to Single Crystal Structural Transformation and
Tunable Proton Conduction Properties. Chem. Mater. 27 (2015) 8116–8125.
S. Begum, Z.Y. Wang, A. Donnadio, F. Costantino, M. Casciola, R. Valiullin, C. Chmelik, M.
ert er, . rger, J. Haase, H. Krautscheid, Water‐Mediated Proton Conduction in a Robust
Triazolyl Phosphonate Metal–Organic Framework with Hydrophilic Nanochannels. Chem.–
Eur. J. 20 (2014) 8862–8866.
[7]
N. Hermer, N. Stock, The new triazine-based porous copper phosphonate

[Cu3(PPT)(H2O)3]·10H2O. Dalton Trans. 44 (2015) 3720–3723.
[8]
[9]
F.P. Zhai, Q.S. Zheng, Z.X. Chen, Y. Ling, X.F. Liu, L.H. Weng, Y.M. Zhou, Crystal
transformation synthesis of a highly stable phosphonate MOF for selective adsorption of CO2.
CrystEngComm 15 (2013) 2040–2043.
C.-Q. Jiao, Z. Zhao, C. Ma, Z.-G. Sun, D.-P. Dong, Y.-Y. Zhu, J. Li, Chiral and Achiral
Copper(II) Carboxyphosphonates Supramolecular Structures: Synthesis, Structures, Surface
Photovoltage, and Magnetic Properties. Cryst. Growth Des. 16 (2016) 5624–5635.
[10] J.A. Sheikh, A. Adhikary, H.S. Jena, S. Biswas, S. Konar, High Nuclearity (Octa‑, Dodeca‑,
and Pentadecanuclear) Metal (M = CoII, NiII) Phosphonate Cages: Synthesis, Structure, and
Magnetic Behavior. Inorg. Chem. 53 (2014) 1606–1613.
[11] C.-I. Yang, Y.-T. Song, Y.-J. Yeh, Y.-H. Liu, T.-W. Tseng, K.-L. Lu. A flexible
tris-phosphonate for the design of copper and cobalt coordination polymers: unusual cage
array topology and magnetic properties. CrystEngComm 13 (2011) 2678–2686.
[12] R. Silbernagel, C.H. Martin, A. Clearfield, Zirconium(IV) Phosphonate–Phosphates as
Efficient Ion-Exchange Materials. Inorg. Chem. 55 (2016) 1651–1656.
[13] M.W. Terban, C. Shi, R. Silbernagel, A. Clearfield, S.J.L. Billinge, Local Environment of
Terbium(III) Ions in Layered Nanocrystalline Zirconium(IV) Phosphonate–Phosphate Ion
Exchange Materials. Inorg. Chem. 56 (2017) 8837–8846.
[14] P. Bhanja, A. Bhaumik, Organic–Inorganic Hybrid Metal Phosphonates as Recyclable
Heterogeneous Catalysts. ChemCatChem 8 (2016) 1607–1616.
[15] X. Chen, Y. Peng, X. Han, Y. Liu, X. Lin, Y. Cui, Sixteen isostructural phosphonate
metal-organic frameworks with controlled Lewis acidity and chemical stability for
asymmetric catalysis. Nat. Commun. 8 (2017) 2171.
[16] H.-L. Sung, C.-H. Lee, J.-E. Wu, Y.-S. Wen, T.-W. Tseng, Z.-J. Hu, T.-M. Her,
Temperature-controlled Cd(II)−phosphonate coordination poly ers: Syntheses, crystal
structures, and luminescent properties. Polyhedron 115 (2016) 54–60.
[17] H.-L. Sung, T.-M. Her, Z.-J. Hu, C.-H. Lee, Synthesis and Characterization of Copper(II)–
Phosphonate Coordination Chain Array of Metallocages. J. Chin. Chem. Soc. 63 (2016)
1000–1006.
[18] H.-L. Sung, T.-M. Her, C.-Y. Chen, Y.-W. Xie, Y.-C. Chang, ariu −phosphonate
coordination layers: Syntheses, crystal structures, and luminescent properties. J. Solid State
Chem. 269 (2019) 271–277.
[19] H.-L. Sung, T.-M. Her, K. Lin, J.-J. Hong, Z.-Y. Wang, Metal ion dominated ligand
conformation variations on phosphonate bridged dinuclear complexes. Inorg. Chim. Acta 466
(2017) 370–375.

[20] H.-L. Sung, Z.-J. Hu, C.-Y. Chen, J.-Y. Wu, Thermally Stable Dinuclear Co(II) and Zn(II)
Complexes of Tetra-phosphonate and 2,2′-Bipyridine. Inorg. Chim. Acta 510 (2020) 119750.
[21] J.W. Steed, D.R. Turner, K.J. Wallace, Core Concepts in Supramolecular Chemistry and
Nanochemistry, John Wiley & Sons, Ltd. England, 2007.
[22] G. R. Desiraju, C–H∙∙∙O and other weak hydrogen bonds. From crystal engineering to virtual
screening. Chem. Commun. (2005) 2995–3001.
[23] O.V. Shishkin, R.I. Zubatyuk, S.V. Shishkina, V.V. Dyakonenko, V.V. Medviediev, Role of
supramolecular synthons in the formation of the supramolecular architecture of molecular crystals
revisited from an energetic viewpoint. Phys. Chem. Chem. Phys. 16 (2014) 6773–6786.
[24] L.C. Gilday, S.W. Robinson, T.A. Barendt, M.J. Langton, B.R. Mullaney, P.D. Beer,
Halogen Bonding in Supramolecular Chemistry. Chem. Rev. 115 (2015) 7118–7195.
[25] G. Cavallo, P. Metrangolo, T. Pilati, G. Resnati, M. Sansotera, G. Terraneo, Halogen bonding:
a general route in anion recognition and coordination. Chem. Soc. Rev. 39 (2010) 3772–
3783.
[26] K. Rissanen, Halogen bonded supramolecular complexes and networks. CrystEngComm 10
(2008) 1107–1113.
[27] P. Metrangolo, F. Meyer, T. Pilati, G. Resnati, G. Terraneo, Mutual induced coordination in
halogen-bonded anionic assemblies with (6,3) cation-templated topologies. Chem. Commun.
(2008) 1635–1637.
[28] C.B. Aakeröy, J. Desper, B.A. Helfrich, P. Metrangolo, T. Pilati, G. Resnati, A. Stevenazzib,
Combining halogen bonds and hydrogen bonds in the modular assembly of heteromeric
infinite 1-D chains. Chem. Commun. (2007) 4236–4238.
[29] R. Bertani, P. Sgarbossa, A. Venzo, F. Lelj, M. Amati, G. Resnati, T. Pilati, P. Metrangolo, G.
Terraneo, Halogen bonding in metal–organic–supramolecular networks. Coord. Chem. Rev.
254 (2010) 677–695.
[30] J.-Z. Gu, J. Wu, A. M. Kirillov, D.-Y. Lv, Y. Tang, J.-C. Wu, Assembling supramolecular
networks by halogen bonding in coordination polymers driven by 5-bromonicotinic acid. J.
Solid State Chem. 213 (2014) 256–267.
[31] S.-Q. Zang, Y.-J. Fan, J.-B. Li, H.-W. Hou, T.C.W. Mak, Halogen Bonding in the Assembly
of Coordination Polymers Based on 5-Iodo-Isophthalic Acid. Cryst. Growth Des. 11 (2011)
3395–3405.
[32] P. Smart, A. Bejarano-Villafuerte, L. Brammer, Coordination chemistry meets halogen
bonding and hydrogen bonding: building networks from 3-iodobenzoate paddlewheel units
[Cu2(3-Ibz)4(L)2]. CrystEngComm 15 (2013) 3151–3159.
[33] A.A. Tehrani, A. Morsali, M. Kubicki, The role of weak hydrogen and halogen bonding

interactions in the assembly of a series of Hg(II) coordination polymers. Dalton Trans. 44
(2015) 5703–5712.
[34] C. von Essen, K. Rissanen, R. Puttreddy, Halogen Bonds in 2,5-Dihalopyridine-Copper(I)
Halide Coordination Polymers. Materials 12 (2019) 3305.
[35] M. Kalaj, K.P. Carter, C.L. Cahill, Utilizing bifurcated halogen-bonding interactions with the
uranyl oxo group in the assembly of a UO2–3-bromo-5-iodobenzoic acid coordination
polymer. Acta Crystallogr. Sect. B 73 (2015) 234–239.
[36] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, SIR92: A program for crystal
structure solution. J. Appl. Crystallogr. 26 (1993) 343–350.
[37] G.M. Sheldrick, Crystal structure refinement with SHELXL. Acta Crystallogr. Sect. C 71
(2015) 3–8.
[38] L.J. Farrugia, WinGX and ORTEP for Windows: an update. J. Appl. Crystallogr. 45 (2012)
849–854.
[39] R.A. Coxall, S.G. Harris, D.K. Henderson, S. Parsons, P.A. Tasker, R.E.P. Winpenny,
Inter-ligand reactions: in situ formation of new polydentate ligands. J. Chem. Soc., Dalton
Trans. (2000) 2349–2356.
[40] M. Fourmigué, Halogen bonding: Recent advances. Curr. Opin. Solid State Mater. Sci. 13
(2009) 36–45.
GRAPHICALABSTRACT