Molecular structures of the products of a diphosphonate ester building block with lewis bases

Article abstract of DOI:10.3390/molecules200814435

By treating a suitable Wittig reagent under acid conditions, the phosphonate ester 1,4-bimethylenebenzene phosphonate ethyl ester (H₂[BBPE], 1) was obtained. As a building block, compound 1 has been reacted with the Lewis-base N,N-dimethylpiperazine, ammonia and NaOH yielded compounds 2-4. The crystal structures show that a 1D chain forming a tubular channel is constructed through hydrogen bonds in 1; hydrogen bonds form two 1D chains with left-hand and right-hand helixes and form 3D networks in compound 2; 1D hydrogen-bond chains are further connected together to afford a 3D network architecture in compound 3; the phosphonate is coordinated by two Na atoms which present different coordination environments in compound 4. Additionally, the relationships between the structure and fluorescence of the four compounds in the solid state and in different solvents have also been studied at room temperature.

Full text of DOI:10.3390/molecules200814435

Molecules 2015, 20, 14435-14450; doi:10.3390/molecules200814435
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Molecular Structures of the Products of a Diphosphonate Ester
Building Block with Lewis Bases
Yufeng Li 1,2 and Fangfang Jian 1,2,
*
1
Microscale Science Institute, Weifang University, Weifang 261061, China;
E-Mail: liyufeng8111@163.com
2
New Materials and Function Coordination Chemistry Lab, Qingdao University of Science &
Technology, Qingdao 266042, China
* Author to whom correspondence should be addressed; E-Mail: ffjian2008@163.com;
Tel./Fax: +86-536-878-5802.
Academic Editor: Derek J. McPhee
Received: 29 December 2014 / Accepted: 23 June 2015 / Published: 7 August 2015
Abstract: By treating a suitable Wittig reagent under acid conditions, the phosphonate
ester 1,4-bimethylenebenzene phosphonate ethyl ester (H2[BBPE], 1) was obtained. As a
building block, compound 1 has been reacted with the Lewis-base N,N-dimethylpiperazine,
ammonia and NaOH yielded compounds 2–4. The crystal structures show that a 1D chain
forming a tubular channel is constructed through hydrogen bonds in 1; hydrogen bonds form
two 1D chains with left-hand and right-hand helixes and form 3D networks in compound 2;
1D hydrogen-bond chains are further connected together to afford a 3D network architecture in
compound 3; the phosphonate is coordinated by two Na atoms which present different
coordination environments in compound 4. Additionally, the relationships between the
structure and fluorescence of the four compounds in the solid state and in different solvents
have also been studied at room temperature.
Keywords: phosphonate ester; synthesis; crystal structure; fluorescence
1. Introduction
Recently, metal phosphonates have attracted a great deal of research interest as a new class of
inorganic-organic materials due to their structural diversity and many potential and practical

Molecules 2015, 20
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applications in the fields of nonlinear optics, catalysis, gas storage, ion exchangers and so on [1–7]. In
all these cases, phosphonates play an important role because of their three oxygen donor atoms [8–10].
Accordingly, by modifying different organic functional groups, the complexing ability of phosphonates
and the corresponding properties of the resulting materials will be changed [11–19]. On the other hand,
multifunctional phosphonates, such as bisphosphonic acids, aminophosphonic acids and carboxyphosphonic
acids, have been proved as good candidates for their potential to form extended hydrogen-bonded
assemblies which could be utilized for the preparation of one-, two-, and three-dimensional
hydrogen-bonded networks and microporous solids [20–27]. For instance, Yuan et al. combined
1-aminoethylidene diphosphonic acid (AEDPH4) and 1-aminopropane-1,1,3 triphosphonic acid
(APTPH6) with 2,2′-bipyridyl-like ligands to build up higher-dimensional supramolecular architectures [3].
Amir et al. produced supramolecular isomerism and isomorphism using the structures of
1,4-butanebisphosphonic acid and its organic ammonium salts [2]. In general, single crystals of metal
phosphonates are difficult to obtain because of their low solubility, so investigations on the structure of
soluble salts of phosphonates are valuable in this field. Sparked by this thought, we designed and
synthesized the diphosphonate ester of 1,4-bimethylenebenzene bisphosphonate ethyl ester (H2[BBPEH2],
1, where BBPEH2 = [O(OC2H5)(HO)PCH2C6H5CH2P(OH) (OC2H5)O]2−} as a bidentate ligand, as
shown in Scheme 1. Furthermore, by using a general solution method and room temperature, 1 acted as
a building block that easily reacted with organic and inorganic bases, and the formed compounds
displayed better solubility in organic solvents or water. We thus obtained compounds 2–4 as shown in
Scheme 2. As expected, the single crystal structure of two self-assembly acid-base hydrogen-bonded
supramolecular architectures and one organic-inorganic hybrid coordination polymer were obtained.
Fluorescence spectra of 1–4 in the solid-state, in methanol and water solutions have been determined.
In this paper, we wish to report the syntheses, crystal structures and fluorescence properties of these
four compounds.
OC2H5
°
150 C
C2H5O
P
OC2H5
CH2Cl
ClCH2
C2H5O
O
O
P
H+
CH2
OC2H5
P
CH2
OC2H5
O
OC2H5
O
H2[BBPEH2] (1)
P
OH
HO
P
CH2
CH2
OC2H5
OC2H5
Scheme 1. Synthesis of compound 1.

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O
P
O
P
N
N
H3C
CH3
(2)
O
4 H2O
NH CH3
H3C
HN
CH2
O
CH2
OC2H5
OHC2H5
O
O
NH3 H2O
+
1
+
2NH4
P
O
2H2O
CH2
O
P
CH2
(3)
(4)
OC2H5
OC2H5
O
O
2Na
CH2
NaOH
O
P
CH2
P
O
OC2H5
OC2H5
Scheme 2. Synthesis of compounds 2–4.
2. Results and Discussion
2.1. Supramolecular Structure of 1
As depicted in Figure 1A, the unit of 1 contains two independent H2[BBPEH2] molecules. In each
molecule, there exists a 2-fold symmetric axis, which lies in the plane of the phenyl ring and passes
through the two middle points of the C5-C5 and C5-C5 bonds. The P-O bond lengths are in the range
of 1.5215(16) and 1.581(2) Å, which match those found in the similar structures [13]. In the unit
lattice, each pair of adjacent H2[BBPEH2] molecules are connected each other by two O2-H1···O2
hydrogen bonds and then, a 1D zigzag chain forming a tubular channel is created, just as shown in
Figure 1B, with the diameter of the channel being 2.384 Å.
A
B
Figure 1. (A) Molecular structure of 1 with atomic numbering and (B) the molecular
arrangement by the hydrogen bonds between adjacent H2[BBPEH2] molecules.

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2.2. Supramolecular Structure of 2
The molecular structure of 2 with atomic numbering is shown in Figure 2A. A unit cell of
compound 2 contains of two [BBPEH2]2− anions, two protonated N,N-dimethylpiperazine cations and
eight lattice water molecules, which are connected together through hydrogen bonds and electrostatic
effects. Each H2[BBPEH2] molecule has lost two protons and transferred them to the
N,N-dimethylpiperazine nitrogen atoms and form a [BBPEH2]2− anion. Both N,N-dimethylpiperazine
nitrogen atoms are protonated. In compound 2, there are two types of anion-cation groups with
different symmetric equivalence. For one type of anion-cation group, the P1=O1 bond length is
1.444(2) Å, and the P1-O2 and P1-O3 bond lengths are 1.675(2) and 1.689(2) Å, respectively. The
[BBPEH2]2− anions and protonated N,N-dimethylpiperazines are connected each other by N1-H1···O2
hydrogen bonds to form a 1D helical chain, which obeys the right-handed rule along an axis (named
1D-R, shown as green-red in Figure 2B). For the other anion-cation group, the P2=O5 bond length is
1.404 (2) Å, and the P2-O4 and P1-O2 bond lengths are 1.463(2) and 1.693(2) Å, respectively. The
[BBPEH2]2− anions and protonated N,N-dimethylpiperazines are joined each other through N2-H2···O5
hydrogen bonds to afford a 1D helical chain, which obeys the left-handed rule along an axis (named
1D-L, shown as blue-yellow in Figure 2D). Four lattice water molecules play important roles in
connecting the 1D chains and further constructing 3D networks (see Figure 2C). The O(2W)-H···O(1)
and O(3W)-H···O(2) hydrogen bonds join the two water molecules [H2O2W and H2O3W] with the
adjacent 1D-R helix chains, respectively, while at the same time the O(4W)-H···O(5) and
O(1W)-H···O(4) hydrogen bonds join the other two water molecules [H2O4W and H2O1W] with the
adjacent 1D-L helix chains, respectively. On the other hand, four water molecules are linked one by
one through O-H···O hydrogen bonds to form a “water cluster chain”, with the O-O distances in the
water cluster ranging between 2.654 and 3.076 Å and the O-H···O bond angles being from 81.49 to
134.63° (see Figure 2C). Finally, the water cluster chains connect all 1D chains together to construct
3D networks in the unit lattice. This 3D networks are further consolidated by some C-H···π interactions
(see Table 1).
A
Figure 2. Cont.

Molecules 2015, 20
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(B)
(C)
(D)
Figure 2. (A) Molecular structure of 2 with atomic numbering, (B) 1D-R right-handed
zigzag chain shown as green-red, (C) 3D supramolcular architecture of 2 constructed by
water chains and two different symmetry equivalent anion-cation groups and (D) 1D-L
left-handed zigzag chain shown as blue-yellow.
Table 1. Selected C-H···π Interactions in Compounds 2, 3 and 4.
C···π
Compound
2
C-H···π
Symmetry Code
∠C-H···π (°)
Centroid-Centroid (Å)
C(14)-H(14B)···Cg(3)
C(14)-H(14B)···Cg(3)
C(17)-H(17B)···Cg(4)
C(17)-H(17B)···Cg(4)
x, −1 + y, z
1−x, 1 − y, −z
x, y, z
3.640
3.640
3.695
3.695
4.044
4.044
3.792
3.792
149.55
149.55
136.52
136.52
164.92
164.92
145.37
145.37
−x, 1 − y, 1 − z
C(5)-H(5A)···Cg(1) −x, −½ + y, ½ − z
3
4
C(5)-H(5A)···Cg(1)
C(2)-H(2B)···Cg(1)
C(2)-H(2B)···Cg(1)
x, −½ − y, ½ + z
x, y, z
−x, −y, −z
In 2, Cg(3) denotes phenyl ring containing C(4)~C(6); Cg(4) denotes phenyl ring containing C(10)~C(12);
in 3, Cg(1) denotes phenyl ring containing C(1)~C(3); in 4, Cg(1) denotes phenyl ring containing C(4)~C(6).
2.3. Supramolecular Structure of 3
The molecular structure of 3 with atomic numbering scheme is shown in Figure 3A. A unit cell of 3
contains two [BBPEH2]2−, four protonated ammonia and four water molecules, which are connected
together through hydrogen bonds and electrostatic effects. Just as in 2, each H2[BBPEH2] molecule has
lost two protons and transferred the protons to two ammonia molecules forming a [BBPEH2]2− anion.
The nitrogen atoms of ammonia are protonated. The cation-anion ratio is 2:1. As shown in Figure 3B,

Molecules 2015, 20
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N(1)-H(1)···O(1) (2.8331 Å) and N(1)-H(6)···O(2) (2.7781 Å) hydrogen bonds firstly join the
[BBPEH2]2− anions to form a 1D chain, and then, in the unit lattice, all of the 1D chains are linked
together forming the 2D array of hydrogen bonds (see Figure 3C) and afford a 3D network architecture
through supramolecular interactions (see Figure 3D). For instance, as shown in Figure 3C, two 1D
chains are linked together through N-H···O hydrogen bonds. The other 1D chains denoted are joined
by the lattice water molecule through O-H···O hydrogen bonds. Further, through N-H···O hydrogen
bond, the lattice water molecule and the protonated ammonia molecule are connected, which
ultimately make the four 1D chains to build up a 3D network architecture. Most important, by
observing the connecting mode among the oxygen and nitrogen atoms in protonated ammonia (see
Figure 3E), one can find two six-membered rings and four five-membered rings.
A
B
C
Figure 3. Cont.

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D
E
Figure 3. (A) Molecular structure of 3 with atomic numbering; (B) 1D chain joined
through N1-H1···O1 and N1-H6···O2 hydrogen bonds; (C) 2D supramolecular network
viewing along the c axis in the unit cell; (D) view of the 3D architecture and (E) stable
connection mode among atoms of oxygen and nitrogen.
The cluster aggregation is controlled by a “vertex-connected” and “edge-sharing” association
mode [28]. The six-membered rings adopt a “puckered-boat” confirmation. It is evident that these
stable five-membered rings and six-membered rings help to strengthen the connection among the
above four 1D chains. In the solid state, the C(5)-H(5A)···Cg(1) and C(5)-H(5A)···Cg(1)
supramolecular interactions (Table 1) help to stabilize the 3D networks.
2.4. Supramolecular Structure of 4
The molecular structure of compound 4 with atomic numbering scheme is shown in Figure 4A.
The X-ray crystal structural analysis indicates that the repeat unit of compound 4 contains one
[BBPEH2]2− anion, two sodium cations, and six water molecules. Although the coordination modes can
be described as a distorted octahedral geometry, there are two types of Na atoms with different modes.
Take Na2 and Na1 cation for instance. Na2 is connected with the Na1 cation through three bridged
oxygen atoms (O3W, O3W and O2W) in one direction, whereas in the opposite direction, the Na2
cation is connected with another sodium cation of Na1 only through one bridged oxygen atom of the
O4W atom from H2O4W. Each of these Na2 cations is connected with two sodium cations, so for the
Na2 cation, its coordination mode can be described by four coordinate oxygen atoms being bridged
with two other sodium cations and two coordinated oxygen atoms from two [BBPEH2]2− anions. As
seen from Figure 4A, for the Na1 cation, its coordination mode is similar to that of Na2, and apart
from four bridged oxygen atoms, two coordinated O1W oxygen atoms come from two water molecules
but not from two [BBPEH2]2− anions as in Na2. As shown in Figure 4A, since each [BBPEH2]2− anion
is a bidentate ligand, coordinated to two sodium cations Na2 with its two apical O2 oxygen atoms. The
Na-O distances are in the 2.413–2.525Å range, which is comparable to that reported for other Na-O

Molecules 2015, 20
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bonds [about 2.455 Å] [29]. It is noticeable that, for the same [BBPEH2]2− anion, its two coordinated
sodium atoms [Na2] adopt the same mode to connect with another two pairs of sodium atoms [Na1],
but the two connecting directions are opposite, just as shown in Figure 4B. All the above coordination
generates a 3D network coordination polymer. Two types of C-H···π interactions (see Table 1) further
consolidate the 3D networks in the lattice.
A
B
C
Figure 4. (A) Molecule structure of 4 with atomic numbering scheme; (B) 2D network in
the unit cell and (C) 3D network coordination polymer.

Molecules 2015, 20
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2.5. Fluorescence Properties
In order to understand the effect of solvents on the crystal structure, the fluorescence spectra for the
compounds 1–4 in the solid-state, in methanol solution and in water solution at 298 K, upon excitation
at 356 nm, have been determined and their fluorescence spectra are shown in Figure 5.
A
B
C
Figure 5. (A) The solid-state emission spectra (ex = 356 nm) for 1–4; (B) The emission spectra
(ex = 356 nm) for 1–4 in methanol solution and (C) The emission spectra (ex = 356 nm)
for 1–4 in water.

Molecules 2015, 20
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Seen from Figure 5A, in the solid-state, 1 exhibits an emission peak at 426 nm. Under the same
experimental conditions, 2, 3 and 4 exhibit emission peaks at 423, 420 and 428 nm, respectively, which
are very similar to that of 1. These emissions can be tentatively ascribed to an intraligand transition.
Based on these similarities, one can deduce that the electron transition modes in 2, 3 and 4 are very
close to that in 1 [30], although the building blocks of [BBPEH2]2− have been connected to form a 3D
network architecture through hydrogen bonds (in 2 and 3 ) or coordination bonds (in 4). On the other
hand, compound 4 has the strongest fluorescence intensity among 1–4, suggesting that the structure of
coordination environment with a Na atom is better for the transfer of electrons than the others.
Although 2 and 3 are both supramolecular compounds constructed with the same [BBPEH2]2− building
block and different organic bases, the fluorescence intensity of 3 is much stronger than that of 2, which
implies that the type of organic base and the type of hydrogen bond in supramolecular compounds
have a direct influence on the electron transitions.
From Figure 5B and Figure 5C, for compound 1, the emission peak in methanol solution is at about
421 nm, which is very near to that in the solid state, indicating the electronic transition mode in
methanol solution is the same as that in the solid-state and the supramolecular skeleton of 1 has not
been destroyed in the methanol solution. On the other hand, in water solution, no evident emission
peak is observed, which suggests that the supramolecular skeleton of 1 in water solution may have
collapsed. For 2, the emission peaks in methanol solution and water solution are both at about 583 nm,
which is a 160 nm red shift compared with that in the solid-state, which implies that the
supramolecular architecture of 2 has been completely degraded down by the solvents and the
electronic transition mode in the solution is different from that in the solid-state. For 3, in the 400–600
nm band no emission peak observed in methanol solution, while in water solution, there is an emission
peak at 423 nm, which differs from that in the solid-state by only 5 nm. For 4, the emission peak in
methanol solution is at about 584 nm, which is a 164 nm red shift compared with that in the solid-state,
while in water solution, the emission peak is at 419 nm, which is almost the same with that observed in
the solid-state. The phenomena in 3 and 4 reveal that for 3 and 4, water is better than methanol to
maintain the molecular construction, which results in the electronic transition modes in the water
solution being the same as those in the solid-state. In methanol solution, the fluorescence spectra of 2
and 4 are red-shifted about 160 nm, indicating that the solid-state skeleton of 2 and 4 has been
destroyed, however, their methanol solution still has intense fluorescence. The fluorescence quantum
yields of 2 and 4 were measured in methanol at room temperature, using rhodamine B as a standard.
Compounds 2 and 4 possessed relative quantum yields of 0.18 and 0.14, respectively, while for 3, after
its supramolecular skeleton is destriyed, no evident emission peak is observed in the 400–600 nm band
in the methanol solution of 3.
Comparing the fluorescence spectra in solution with those in the solid-state, one can find that: (1)
the coordination bond is powerful to transfer electrons; (2) solvents have remarkable influences on
maintaining the skeletons. Sometimes, the constructs can remain intact in the solvents, such as 3 and 4
in water solution and 1 in methanol solution, and sometimes, solvents will destroy the skeletons, such
as 2 in water and methanol solutions.

Molecules 2015, 20
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3. Experimental Section
3.1. Materials and Methods
All chemicals were of analytical reagent grade and used directly without further purification.
Elemental analyses for carbon, hydrogen and nitrogen were performed by a Perkin-Elmer 240 °C
Elemental instrument (Waltham, MA, USA). Infrared spectra (4000–400 cm−1) were recorded
with KBr optics on a Nicolet AVATAR 360 FTIR spectrophotometer (Waltham, MA, USA). The
photoluminescence spectra were examined with a HITACHI F-4500 fluorescence spectrophotometer
(Tokyo, Japan) equipped with a xenon lamp as the excitation source. Single crystals of this series
compounds were obtained in high yield. As a result, all emission data were tested, using single crystals
without any impurities as starting materials.
3.2. Synthesis of H2[BBPEH2] (1)
The reaction path is shown in Scheme 1. To a toluene solution of 1,4-bis(chloromethyl)benzene
(17.5 g, 0.1 mol) was added dropwise triethyl phosphite (33.2 g, 0.2 mol) and the mixture was stirred
at 150 °C. Two h later, the reaction mixture was cooled to room temperature. Removal of solvent from
the reaction mixture in vacuo afforded the corresponding product as a white solid [31] which was
further washed with petroleum ether, and finally hydrolyzed in sulfuric acid (5 mol/L) at 40 °C with
stirring (yield 86%). The colorless block crystals of 1,4-bismethylenebenzene bisphosphonate ethyl
ester (H2[BBPEH2]) were recrystallized from a mixed solvent of ethanol and distilled water (1:1) one
week later. Elemental analysis (%), Calcd. for C12H16O6P2: C, 45.28; H, 5.07. Found: C, 45.45;
H, 4.89. As the building block, 1 was reacted with the Lewis bases N,N-dimethylpiperazine, ammonia
and sodium hydroxide. H2[BBPEH2], has changed from a tetrabasic acid into a binary acid and then,
further deprotonated to become the [BBPEH2]2− anion.
3.3. Synthesis of [BBPEH2]2−·[Protonated N,N-dimethylpiperazine]2+·4H2O (2)
Compound 1 (644 mg, 2.0 mmol) was dissolved in the mixture of water (10.0 mL) and ethanol
(10.0 mL) with stirring and then put into a straight glass tube. N,N-dimethylpiperazine (0.27 mL,
2.0 mmol) was carefully layered onto it. Colorless block crystals were observed after one week.
Elemental analysis (%), Calcd. for C36H80N4O20P4: C, 42.67; H, 7.96; N, 5.53. Found: C, 42.80;
H, 7.85; N, 5.72.
3.4. Synthesis of [BBPEH2]2−·[NH4]22+·2H2O (3)
The same procedure as for 2 was used. Ammonia (0.160 mL, 4.0 mmol) was used in place of
N,N-dimethylpiperazine and colorless block crystals were obtained after one week. Elemental analysis
(%), Calcd. for C12H30N2O8P2: C, 36.72; H, 7.71; N, 7.14. Found: C, 36.90; H, 6.89; N, 7.30.
3.5. Synthesis of {[BBPEH2]·[Na2(H2O)6]}∞ (4)
Compound 1 (644 mg, 2.0 mmol) and sodium hydroxide (160 mg, 4.0 mmol) were dissolved in a
mixture of water (10.0 mL) and ethanol (10.0 mL) with stirring. Upon slow evaporation of the solvents

Molecules 2015, 20
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at room temperature, colorless block single crystals suitable for X-ray analysis were obtained after one
week. Elemental analysis (%), Calcd. for C6H9NaO6P: C, 31.17; H, 3.93. Found: C, 32.12; H, 3.73.
3.6. Single Crystal X-ray Diffraction Studies
The diffraction data for 1–4 were collected on a Enraf-Nonius CAD-4 diffractometer with graphite-
monchromated Mo-Kα radiation [λ = 0.71073 Å, T = 293(2) K] by ω-scan mode. The structures were
solved by direct methods and refined by least squares on F2 by using the SHELXTL [32] software
package. All non-hydrogen atoms were anisotropically refined. The hydrogen atom positions were
fixed geometrically at calculated distances and allowed to ride on the parent carbon atoms. The
molecular graphics were plotted using SHELXTL. Atomic scattering factors and anomalous dispersion
corrections were taken from International Tables for X-ray Crystallography [33]. Further detailed
information regarding the crystallographic data and structural analysis for 1–4 is listed in Table 2.
Table 3 lists the hydrogen bonds in the compounds 1–3. All the bond distances and bond angles of the
four compounds are in the normal ranges. Mercury (version 3.0, CCDC, Cambridge, UK) and Dimond
3.0 software (CRYSTAL IMPACT, Bonn, Germany) were used to visualize the structures. Some
C-H···π interactions in compounds 2, 3 and 4 are listed in Table 1.
Table 2. Crystal Data and Structure Refinement Summary for Compounds 1–4.
Empirical Formula
C6H8O3P
C18H40N2O10P2
C6 H15NO4P
C12H30Na2O12P2
M
crystal size/mm
T/K
159.09
506.46
196.16
474.28
0.24 × 0.20 × 0.16 0.30 × 0.18 × 0.14 0.22 × 0.20 × 0.18 0.24 × 0.22 × 0.18
293(2)
0.71073
monoclinic
C2
293(2)
0.71073
centric
293(2)
0.71073
centric
293(2)
0.71073
centric
Pnma
λ/Å
crystal system
space group
a/Å
P-1
P-1
13.431(3)
8.8309(18)
7.7810(16)
90
9.3520(19)
10.458(2)
15.736(3)
81.56(3)
82.84(3)
63.46(3)
1358.9(5)
2
13.079(3)
9.1170(18)
8.9340(18)
89.88(3)
107.82(3)
90.02(3)
1014.2(4)
4
8.2010(16)
28.502(6)
9.7120(19)
90
b/Å
c/Å
α/deg
β/deg
γ/deg
V/Å3
123.98(3)
90
90
90
765.3(3)
4
2270.1(8)
4
Z
ρ
calcd/g.cm−3
1.381
1.238
1.285
1.352
F (000)
332
544
420
952
μ/mm−1
0.304
0.208
0.252
0.280
θ range/deg
completeness to θ
2.94 to 26.98
98.7%
1.31 to 29.31
74.9%
1.64 to 26.97
97.2%
1.43 to 25.00
99.6%
−17 ≤ h ≤ 14,
−11 ≤ k ≤ 11,
0 ≤ l ≤ 9
0 ≤ h ≤ 11,
−11 ≤ k ≤ 12,
−18 ≤ l ≤ 18
−15 ≤ h ≤ 15,
−10 ≤ k ≤ 10,
0 ≤ l ≤ 10
0 ≤ h ≤ 9,
−33 ≤ k ≤ 0,
0 ≤ l ≤ 11
range of h, k, l
reflections
1773/881
6013/5585
4426/2150
2035/2035
collected/unique

Molecules 2015, 20
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Table 2. Cont.
Empirical Formula
C6H8O3P
0.0334
C18H40N2O10P2
0.1221
C6 H15NO4P
0.0691
C12H30Na2O12P2
0.0000
Rint
data/restraints/parameters
GOF on F2
881/1/60
5585/0/297
1.027
2150/2/134
1.086
2035/0/133
1.065
1.144
final R indices
[I > 2σ (I)]
R1 = 0.0504
wR2 = 0.1373
R1 = 0.0545
wR2 = 0.1416
0.600 and
−0.358
R1 = 0.0574
wR2 = 0.1688
R1 = 0.0954
wR2 = 0.1946
R1 = 0.0374
wR2 = 0.0994
R1 = 0.0496
wR2 = 0.1069
R1 = 0.0962
wR2 = 0.2405
R1 = 0.1459
wR2 = 0.2891
R indices (all data)
peak, hole/e.Å−3
0.584 and −0.610 0.350 and −0.378
1.396 and −1.108
Table 3. Selected Hydrogen Bond Lengths (Å) and Angles (°) for Compounds 1–3.
Compound
1
D-H···A
Symmetry Code
−x, y, −z
D···A (Å) ∠D-H···A (°)
O(2)-H(1)···O(2)
2.5114
2.6265
3.0756
2.8627
3.0145
2.9162
2.8216
2.8338
2.7913
2.8304
2.7767
165.95
175.86
126.99
155.48
164.35
172.15
164.14
168.93
171.10
162.13
169.00
N(1)-H(1)···O(2)
x, −1 + y, z
O(1w)-H(11W)···O(4W)
O(2W)-H(12W)···O(1)
O(3W)-H(13W)···O(2)
O(4W)-H(14W)···O(5)
O(1W)-H(21W)···O(4)
N (1)-H(1)···O(1)
−1 + x, y, z
−1 + x, y, z
2
3
2 − x, 1 − y, −z
1 − x, 1 − y, 1 − z
x, −1 + y, z
x, ½ − y, ½ + z
x, ½ − y, ½ + z
1 − x, −1/2 + y, ½ − z
1 − x, ½ + y, ½ − z
O(2W)-H(3)···O(2)
N(1)-H(5)···O(2W)
N(1)-H(6)···O(2)
4. Conclusions
By using 1 as the building block, hydrogen-bonded supramolecules and coordinated polymers have
been obtained by reaction with Lewis bases. X-ray single crystal diffraction shows that the differences
in the structures of the in/organic bases lead to organophosphonic ester supramolecular and
coordination polymer structures ranging from 1D helix chains to 3D networks. Solid state fluorescence
spectra show that the fluorescence intensities of 1–4 are very different from each other, which indicate
that the different types of base in the compounds have direct effects on the fluorescence intensity.
Fluorescence spectra in solutions indicate that solvents have remarkable influencs on maintaining the
integrity of the molecular skeletons. In a larger sense, compound 1 with multiple phosphonate groups
can be used to construct higher-dimensional and stable supramolecular architectures extending other
alkalis because of its good solubility. In additional, they can be used as models to design new metal
phosphonates and explore the variety of structural possibilities in forming organic-inorganic hybrid
materials and metal-organic frameworks. Work is currently underway to synthesize metal
organophosphonic esters and study the correlation factors that affect the structures and properties.

Molecules 2015, 20
14448
Supplementary Material
The crystallographic file in cif format for 1–4 compounds has been deposited with CCDC number
710324–710327. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html. Supplementary materials can be accessed at: http://www.mdpi.com/1420-
3049/20/08/14435/s1.
Acknowledgments
This work was supported by the Natural Science Foundation of Shandong Province, China. (No.
Z2007B01 and Y2007B14).
Author Contributions
Yufeng Li and Fangfang Jian designed research; Yufeng Li performed research and analyzed the
data; Yufeng Li and Fangfang Jian wrote the paper. All authors read and approved the final manuscript.
Conflicts of Interest
The authors declare no conflict of interest.
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distributed under the terms and conditions of the Creative Commons Attribution license
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