New multifunctional phosphonic acid for metal phosphonate synthesis

Article abstract of DOI:10.1016/j.molstruc.2012.11.069

A new heterotopic phosphonic acid, 3-amino-5-(dihydroxyphosphoryl)benzoic acid (1) has been synthesized and obtained in the crystalline form. Second multifunctional phosphonic acid-namely 3-(dihydroxyphosphoryl)-5-nitrobenzoic acid (2) has also been obtai

Full text of DOI:10.1016/j.molstruc.2012.11.069

Journal of Molecular Structure 1036 (2013) 505–509
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Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
New multifunctional phosphonic acid for metal phosphonate synthesis
b
a,
Piotr Garczarek a, , Jan Janczak , Jerzy Zon
⇑
⇑
´
a
_
Department of Medicinal Chemistry and Microbiology, Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspian´skiego 27, 50-370 Wrocław, Poland
b Institute of Low Temperatures and Structure Research, Polish Academy of Sciences, 2 Okólna St., P.O.Box 1410, 50-950 Wrocław, Poland
h i g h l i g h t s
"
"
"
A new multifunctional phosphonic acid, 3-amino-5-(dihydroxyphosphoryl)benzoic acid, has been synthesized and characterized.
It crystallizes in Pꢀ1 space group and forms a three dimensional supramolecular structure using seven hydrogen bonds.
Molecular structure makes it potentially interesting for synthesis of open framework metal phosphonates.
a r t i c l e i n f o
a b s t r a c t
Article history:
A new heterotopic phosphonic acid, 3-amino-5-(dihydroxyphosphoryl)benzoic acid (1) has been synthe-
sized and obtained in the crystalline form. Second multifunctional phosphonic acid – namely 3-(dihydr-
oxyphosphoryl)-5-nitrobenzoic acid (2) has also been obtained, following a different synthetic route than
previously reported. Compound 1 crystallizes in a centrosymmetric space group of the triclinic system as
monohydrate, AC6H3(NH2)(COOH)PO3H2ꢁH2O – 1a. The molecule in the crystal exists in a zwitterionic
form, in which one of the proton of the phosphonic group is transferred to the amine group. The zwitter-
ionic molecules interact to each other and with water molecules via NAH. . .O and OAH. . .O hydrogen
bonds forming a three-dimensional network.
Received 8 November 2012
Received in revised form 29 November 2012
Accepted 29 November 2012
Available online 11 December 2012
Keywords:
Phosphonic acid
Metal phosphonate
Metal–organic framework
Supramolecular chemistry
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
research field. First phosphonate based hybrid materials were syn-
thesized by Alberti et al. [10].
Metal organic frameworks (MOFs) have received much atten-
tion from many research groups around the world in the last ten
years [1,2]. This fact is not surprising as MOF materials form a
new class of hybrid compounds – often porous – that posses
numerous potential industrial and social applications. Gas storage
[3] and separation [4], catalysis [5], drug delivery [6] and non-lin-
ear optics [7] are just some of them. The most promising feature of
MOF materials is the potential ability to fine-tune the size and
shape of its pores as well as their functionality.
The most popular O-donor organic species used in metal–or-
ganic framework synthesis are carboxylic acids. There are several
known carboxylic ligands and some of them like 1,4-benzenedi-
carboxylic acids are already considered substrates for industrial-
scale MOF synthesis [8]. Along with them, there is another impor-
tant group of O-donor, which are phosphonic acids [9]. These
compounds, although not so popular in MOF synthesis as carbox-
ylic acids and having some drawbacks, still pose an interesting
Most of already used phosphonic acids formed layered-pillared
networks when reacting with metal ion species. It is a matter of
concern for researchers to obtain metal phosphonate porous mate-
rials, that do not have the layer-pillared architecture. Layer-
pillared metal phosphonates are already well studied by Clearfield
and co-workers [11,12]. Although materials of such topology can
posses some porosity they also have some disadvantages. As poros-
ity is mostly achieved by using a phosphate or small monophosph-
onate as a co-ligand – so called spacers – pores tend to have wide
size distribution owning to the random distribution of spacers. On
the other hand non-layered metal-phosphonates tend to form open
frameworks. Synthesis of MP’s that not posses such topology can
be achieved by using two different approaches [2]. The first one
is to use organic ligands that are not linear. Change of angle be-
tween binding phosphonate groups interacting with metal moie-
ties can usually let one to acquire metal organic phosphonate
framework of non-layered topology. One example of such ligand
is methylenediphosphonic acid [13]. The second approach con-
cerns using ligands with additional functional groups that have
the ability to chelate metal ions thus braking the tendency to form
layered structure. Such groups are: carboxylic [14], hydroxyl, and
⇑
Corresponding authors. Fax: +48 71 3284064.
E-mail addresses: piotr.garczarek@pwr.wroc.pl (P. Garczarek), jerzy.zon@pwr.
wroc.pl (J. Zon´ ).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.11.069

506
P. Garczarek et al. / Journal of Molecular Structure 1036 (2013) 505–509
amine. One can also use a pyridine moiety with its nitrogen atom
acting as a binding group.
(10 ml) and water (10 ml) were added. pH was adjusted to nine
using 3 M sodium hydroxide solution. Next additional ethyl ace-
tate (10 ml) and water (10 ml) were added and phase were sepa-
rated. Organic phase was washed with brine (10 ml) and dried
over anhydrous magnesium sulfate. Drying agent was filtered
and solvent was evaporated to afford 6 (0.323 g, 59%) mp. 93–
96 °C. 1H NMR (CDCl3) d: 7.97 (s, 1H arom. H); 7.52 (s, 1H, arom.
H); 7.02 (s, 1H, arom. H); 3.88 (s. 3H, CH3);
In this paper we report the syntheses of two multifunctional
phopsphonic acids potentially interesting in hybrid materials sci-
ence: 3-amino-5-(dihydroxyphosphoryl)benzoic acid – 1 and 3-
(dihydroxyphosphoryl)-5-nitrobenzoic acid – 2, as well as crystal
structure of the former compound. The synthesis of the latter com-
pound has been conducted in a different way to previously de-
scribed [15].
Methyl 3-amino-5-(diethoxyphosphoryl)benzoate (7).
A 50 ml
round bottomed flask was charged with 6 (1.00 g, 4.34 mmol), ace-
tonitryl (10 ml), diethyl phosphite (0.718 g, 5.20 mmol) and ethyl-
diisopropylamine (0.729 g, 5.64 mmol). The flask was flushed with
argon for 15 min. and palladium acetate (0.009 g, 0.0434 mmol)
and dppf (0.026 g, 0.047 mmol) were added. Reaction mixture
was heated to 90 °C and this temperature was maintained for
20 h. After that the mixture was cooled to room temperature and
solvent was evaporated. The residue was purified by column chro-
matography on silica gel using ethyl acetate as eluent to afford 7
(1.77 g, 94%). 1H NMR (CDCl3) d: 7.82 (d, J = 15.0 Hz, 1H, arom.
H); 7.57 (s, 1H, arom. H); 7.42 (d, J = 15.0 Hz, 1H, arom. H); 4.13
(m, 4H, CH2); 3.90 (s, 3H, CH3); 1.32 (m, 6H, CH3); 31P NMR (CDCl3)
d: 17.92;
2. Experimental
2.1. Materials and methods
All starting materials and solvents were used as received. The
1H, 13C and 31P NMR spectra were recorded on a Bruker Avance
DRX300 instrument operating at 300.13 MHz (1H), 121.50 (31P)
and 75.46 (13C). Chemical shifts are in ppm. IR spectra were mea-
sured on a Perkin–Elmer 1600 spectrometer as KBr discs. Elemen-
tal analysis was performed on a Elementar vario EL III apparatus.
2.2. Synthesis
3-amino-5-(dihydroxyphosphoryl)benzoic acid (1). 6 (0.868 g,
2.75 mmol) was placed in a 25 ml round-bottomed flask, concen-
trated hydrochloric acid (6 ml) and water (6 ml) were added. The
mixture was refluxed for 10 h and then cooled to room tempera-
ture. Solvent was evaporated in vacuum, residue was dissolved in
small amount of water. Evaporation and dissolution was repeated.
Finally product was filtered off and dried to give 0.475 g (80%) of 1
(mp. >360 °C).1H NMR (d6-DMSO) d: 7.42 (d, J = 13.2 Hz, 1H, arom.
H), 7.26 (s, 1H, arom. H), 7.13 (d, J = 13.6 Hz, 1H, arom. H); 13C NMR
(d6-DMSO) d: 167.87, 148.74, 135.19, 131.17, 120.44, 119.50,
117.229; 31P{1H} NMR (d6-DMSO) d: 13.70; C7H8NO5PꢂH2O
(235,13) calc. C 35.76; H 4.29; N 5.96; found C 35.71; H 4.19; N
5.88; IR (KBr) 3222, 3041, 2800, 2578, 1884, 1686, 1531, 1297,
Methyl 3-bromo-5-nitrobenzoate (4). 4 was synthesized using
previously reported procedure [16]. Yield: 2.22 g (31%), mp. = 71–
74 °C (lit. 70–71 °C. [16])
Methyl 3-(diisopropyloxyphosphoryl)-5-nitrobenzoate (5). To a
50 ml round-bottomed flask containing 4 (2.18 g, 8.36 mmol), ace-
tonitrile (15 ml), diisopropyl phosphite (1.67 g, 10.03 mmol), diiso-
propylethylamine (1.41 g, 1087 mmol), palladium acetate (0.019 g;
0.084 mmol) and dppf (0.051 g, 0092 mmol) were added. The flask
was put under reflux condenser and was flushed with argon
(15 min.). Then it was put in an oil bath heated to 85 °C and kept
there for 20 h under argon. After that the mixture was cooled to
room temperature and the solvent was evaporated in vacuo. The
residue was separated between water (10 ml) and ethyl acetate
(10 ml). Water phase was extracted with ethyl acetate (10 ml),
and the mixed organic phases were washed with brine (10 ml)
and dried over anhydrous magnesium sulfate. Afterwards drying
agent was filtered off and ethyl acetate was evaporated in vacuum
to give 2.62 g of crude product. Column chromatography on silica
gel using ethyl acetate as eluent gave pure 5 (0.826 g, 28%). 1H
NMR (CDCl3) d: 9.00 (s, 2H, arom. H), 8.78 (t, J = 10.9 Hz, 2H, arom.
H), 4.78 (m, 2H, CH), 4.01 (s, 3H, CH3), 1.42 (d, J = 6.1, 6H, CH3), 1.27
(d, J = 6.2, 6H, CH3); 31P{1H} NMR (CDCl3) d: 11.85.
1127 cmꢀ1
[M+H]+ = 218.0213;
;
MS:
m/z = 218.0214,
calc
for
C7H9NO5P
2.3. Single crystal X-ray data collection and structure determination
A colorless single crystal of 1a was used for data collection on a
four-circle KUMA KM4 diffractometer equipped with a two-
dimensional CCD area detector. The graphite monochromatized
Mo Ka radiation and the x-scan technique (Dx = 1°) were used
for data collection. The data collection and reduction along with
absorption correction were performed using CrysAlis software
package [17]. The structure was solved by direct methods using
SHELXS-97 [18] that revealed positions of almost all non-hydrogen
atoms. The remaining atoms were located from subsequent differ-
ence Fourier syntheses. The structure was refined using SHELXL-97
[18] with the anisotropic thermal displacement parameters. The
hydrogen atoms joined to the aromatic ring were refined with
the riding model, the H atoms involved in the hydrogen bonds
were refined. Visualization of the structure was made with the Dia-
mond 3.0 program [19]. Refinement detail and crystallographic
data for 1a are listed in Table 1.
3-(dihydroxyphosphoryl)-5-nitrobenzoic acid (2). A 25 ml round-
bottomed flask was charged with methyl 3-(diisopropyloxyphos-
phoryl)-5-nitrobenzoate (0.773 g, 2.24 mmol). Concentrated
hydrochloric acid (3 ml) and water (3 ml) were added and the mix-
ture was heated in reflux for 12 h. After cooling it was diluted with
water (5 ml), and charcoal was added. Mixture was heated to re-
flux and charcoal was filtered off. Filtrate was evaporated to dry-
ness and the residue was dissolved in small amount of water and
again water was evaporated. This action were repeated with etha-
nol. Finally 0.469 g (85%) of 2 were obtained (mp. 217–220 °C). 1
H
C
NMR (d6-DMSO) d: 8.66 (s, 1H, arom. H), 8.53 (m, 2H, arom. H); 13
NMR (d6-DMSO) d: 165.53, 148.24, 138.08, 136.97, 133.14, 128.88,
126.18 31P{1H} NMR (CDCl3) d: 8.40; IR (KBr) 3383, 3106, 3081,
3. Results and discussion
2880, 2671, 1698, 1542, 1352, 1193, 1028 cmꢀ1
; MS: m/
z = 245.9837, calc for C7H5NO7P [MꢀH]ꢀ = 245.9809;
3-amino-5-(dihydroxyphosphoryl)benzoic acid (1) was synthe-
sized from methyl 3-nitrobenzoate (3) in a four-step procedure as
shown in Scheme 1. Firstly the compound 3 was brominated using
bromine in concentrated sulfuric acid in 90 °C over a period of 2 h.
The resulting bromonitrocompound (4) was reduced with tin (II)
chloride in ethyl acetate in the presence of water. Following was
Methyl 3-amino-5-bromobenzoate (6). A 50 ml round bottomed
flask was charged with a solution of 4 (0.626 g, 2.4 mmol) in ethyl
acetate (10 ml). Then tin (II) chloride (2.27 g, 12 mmol) and water
(0.432 g, 24 mmol) were added and the reaction mixture was re-
fluxed for 30 min. After cooling to room temperature ethyl acetate

P. Garczarek et al. / Journal of Molecular Structure 1036 (2013) 505–509
507
Table 1
Crystallographic data for 1a.
consists of one molecule of 3-amino-5-(dihydroxyphosphoryl)-
benzoic acid and one molecule of water (Fig. 1a).
Molecule of 1 exists in the crystal in a zwitterionic form in
which the proton from the phosphonic group as a stronger acidic
group than carboxyl is transferred to the amino group forming
the NHþ3 . Due to deprotonation of the dihydroxyphosphoryl group
two of three PAO bonds are almost equal and shorter than the
third PAO bond (Table 2).
The CAO bond lengths of the carboxyl group are typical for the
non-dissociated group (C@O, 1.219(3) and CAOH, 1.308(3)). The
conformation of the molecule of 1 can be defined by the orienta-
tion of the carboxyl, phosphoryl and ammonium groups in relation
to the planar aromatic ring. The carboxyl group of 1 is almost
coplanar with the aromatic ring (3.3(2)°), while the orientation of
the PO3Hꢀ can be given by a torsion – angle of C6AC1AP1AO2
(ꢀ28.0(2)). One of the hydrogen atom of the NHþ3 group is almost
coplanar with the ring (the torsion angle of C4AC5AN1AH13 is
equal to 4(2)°), which is not an uncommon feature in structures
containing a protonated aromatic amine.
The zwitterionic molecules of 1 in the crystal of 1a interact via
relatively short OAHꢁ ꢁ ꢁO hydrogen bonds (O5ꢁ ꢁ ꢁO2 = 2.559(3) Å,
Table 3) between the carboxyl group of one molecule and the oxy-
gen atom (O2) the of phosphonate group of the other forming one
dimensional chains along the [001] direction (Fig. 1b).
The chains are interconnected by the water molecules that
serve as a donor and as an acceptor of the hydrogen bonds, and
by the NAHꢁ ꢁ ꢁO hydrogen bonds between the ammonium group
and one oxygen atom (O2) of the phosphonate group forming a
double chain (Fig. 1b). The zwitterionic 3-amino-5-(dihydroxy-
phosphoryl)-benzoic acid molecules within the chain related by
an inversion center interact by a pair of NAHꢁ ꢁ ꢁO hydrogen bonds
forming centrosymmetric dimers with a graph of R22ð14Þ. Repetitive
translational occurrence of such dimers forms a three-dimensional
hydrogen bonding supramolecular network (Fig. 1c).
Empirical formula
C7H8NO5PꢁH2O
Formula weight (g molꢀ1
)
235.13
ꢀ
Crystal system, space group
Triclinic, P 1 (No. 2)
a (Å)
b (Å)
c (Å)
6.7086(13)
8.4972(17)
8.7745(18)
107.83(2)
92.73(1)
95.18(1)
472.72(16)
2
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc/Dobs (g cmꢀ3
l
)
1.652 / 1.65
0.301
244
(mmꢀ1
)
F(000)
Crystal size (mm)
Radiation type, wavelength, k (Å)
Temperature (K)
h range (°)
Absorption correction
0.27 ꢃ 0.21 ꢃ 0.15
Mo Ka, 0.71073
295(2)
2.92–29.41
Numerical, CrysAlis Red
0.9272/0.9581
6551/2384/1496
0.0404
Tmin/Tmax
Reflections collected/unique/observed
Rint
Refinement on
F2
0.0478
0.1265
1.002
R[F2 > 2
r
(F2)]
wR(F2 all reflections)
Goodness-of-fit, S
D
qmax
,
D
qmin (e Å–3
)
+0.563, ꢀ0.325
wR = {
R
[w(F2o ꢀ F2c Þ ]/
R
wF1o4=2; wꢀ1 = (
r
2(F2o ) + (0.068P)2) where P = (Fo2 þ 2F2c )/3.
2
catalytic phosphonylation of 4 using palladium catalyst. Phospho-
nate ester was purified with column chromathography. The last
step was acidic hydrolysis of the ester which yielded compound
1. Synthesis of 3-(dihydroxyphosphoryl)-5-nitrobenzoic acid (2)
was achieved in three steps. The first step was the same as in the
synthesis of 1. In the next step bromide was phosphonylated using
palladium catalyst. Phosponate (5) was then hydrolyzed using
hydrochloric acid to afford 2.
Single crystals suitable for X-ray measurements were obtained
by recrystalization of 1 from water. Despite numerous trails using
different solvents recrystalization of 2 was not achieved. Com-
pound 1 crystallizes in the centrosymmetric space group of the tri-
clinic system as monohydrate (1a). The asymmetric unit of 1a
All H atoms of the ammonium group (ANHþ3 ) and H atom of car-
boxyl (COOH) and phosphonate (PO3Hꢀ) groups are involved as do-
nors in hydrogen bonds. Thus each zwitterionic molecule of 1 in
the crystal of 1a forms as the donor five hydrogen bonds, three
NAHꢁ ꢁ ꢁO and two OAHꢁ ꢁ ꢁO. In addition each zwitterionic molecule
is an acceptor of three hydrogen bonds. The water molecules inter-
connect the one-dimensional chains via three OAHꢁ ꢁ ꢁO hydrogen
bonds, in two of them the water molecules act as the donor and
P(O)(Oi-C3H7)2
ii
NO2
NO2
i
COOCH3
COOCH3
O2N
COOCH3
Br
5
4
3
iv
P(O)(OC2H5)2
Br
v
iii
COOCH3
7
COOCH3
H2N
H2N
6
iii
P(O)(OH)2
P(O)(OH)2
COOH
2
O2N
COOH
1
H2N
Scheme 1. Synthesis of 1 and 2. Reagents: (i) Br2, Ag2SO4, conc. H2SO4; (ii) H(O)P(OiAPr)2, Pr2NEt, Pd(OAc)2, dppf; (iii) conc. HCl, H2O; (iv) SnCl2, H2O, AcOEt; (v) H(O)P(OEt)2,
Pr2NEt, Pd(OAc)2, dppf.

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P. Garczarek et al. / Journal of Molecular Structure 1036 (2013) 505–509
Fig. 1. (a) View of the molecular structure of 1a. Displacement ellipsoids are shown at the 50% probability level; (b) view of the OAHꢁ ꢁ ꢁO hydrogen bonded chains of
zwitterionic 3-amino-5-(dihydroxyphosphoryl)-benzoic acid molecules. H atoms joined to the ring are omitted for clarity. (Symmetry codes as in Table 3); (c) molecular
packing of 1 showing the layered structure. H atoms joined to the ring are omitted for clarity. Dashed lines represent the OAHꢁ ꢁ ꢁO and NAHꢁ ꢁ ꢁO hydrogen bonds.
Table 2
Table 3
Selected geometrical parameters (Å, °).
Geometry of the hydrogen bonds (Å, °).
P1AO1
P1AO3
C3AC7
C7AO4
O1AP1AO2
O2AP1AO3
C2AC3AC7AO5
C6AC1AP1AO2
1.5029(19)
1.559(2)
1.496(3)
1.219(3)
114.71(11)
111.57(11)
3.3(3)
P1AO2
C1AP1
C5AN1
C7AO5
O1AP1AO3
O4AC7AO5
C6AC1AP1AO1
C6AC1AP1AO3
1.5006(18)
1.802(3)
1.467(3)
1.308(3)
106.17(11)
123.5(2)
97.7(2)
DAHꢁ ꢁ ꢁA
DAH (Å)
Hꢁ ꢁ ꢁA (Å)
Dꢁ ꢁ ꢁA (Å)
DAHꢁ ꢁ ꢁA (°)
O3AH3ꢁ ꢁ ꢁO6i
0.79(3)
0.95(3)
0.91(3)
0.92(3)
1.01(3)
0.81(3)
0.82(3)
1.83(3)
1.62(3)
1.88(3)
1.85(3)
1.89(3)
2.03(3)
1.97(3)
2.599(3)
2.559(3)
2.761(3)
2.761(3)
2.727(3)
2.810(3)
2.786(3)
165(3)
167(3)
163(3)
159(3)
154(2)
160(4)
173(4)
O5AH5ꢁ ꢁ ꢁO2ii
N1AH11ꢁ ꢁ ꢁO1iii
N1AH12ꢁ ꢁ ꢁO2i
N1AH13ꢁ ꢁ ꢁO1iv
O6AH61ꢁ ꢁ ꢁO1iii
O6AH62ꢁ ꢁ ꢁO4v
ꢀ28.0(2)
ꢀ147.8(2)
Symmetry code: (i) ꢀx+1, ꢀy+1, ꢀz+1; (ii) x, y, z+1; (iii) ꢀx, ꢀy+1, ꢀz+1; (iv) z, yꢀ1,
z; (v) x, y, zꢀ1.
in one as the acceptor. Thus the water molecule interacts with
three neighboring molecules of 1
Hydrogen bonds observed in the structure of 1 result in the
organization of molecules in the layered structure. One can notice
that the layers stacked along the a axis are shifted against each
other along the c axis. Moreover molecules of the adjacent layers
are ‘facing’ in the opposite direction. This is due to formation of
hydrogen bonds between phosphonic and amino groups. Two
‘types’ of layers can be therefore distinguished, designated A and
B, formed in a ABABAB. . . mode along the a axis. Formation of
zig–zag sheets stretching in the direction of a axis and connected
with adjacent sheets along b and c axes is also visible.

P. Garczarek et al. / Journal of Molecular Structure 1036 (2013) 505–509
509
4. Conclusion
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Supplementary materials
Details on data collection and refinement, fractional atomic
coordinates, anisotropic displacement parameters and full list of
bond lengths and angles in CIF format has been deposited at the
Cambridge Crystallographic Data Centre, No. CCDC 817610 for
1a. Copies of this information can be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax:
+44 1223 336 033; email: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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Acknowledgements
The authors acknowledge with thanks financial support from
Ministry of Science and Higher Education (Poland) and Wrocław
University of Technology.