Novel lead(II) carboxylate-arsonate hybrids

Article abstract of DOI:10.1016/j.jssc.2008.03.002

Hydrothermal reactions of lead(II) acetate with phenylarsonic acid (H₂L¹) (or 4-hydroxy-3-nitrophenylarsonic acid, H₃L²) and 5-sulfoisophthalic acid monosodium salt (NaH₂SIP) (or 1,3,5-benzenetricarboxylic acid (H₃BTC)) as the second metal linkers afforded three novel mixed-ligand lead(II) carboxylate-arsonates, namely, Pb₅(SIP)₂(L¹)₂(H₂O) 1, Pb₃(SIP)(L²)(H₂O) 2 and Pb(H₂L²)(H₂BTC) 3. The structure of 1 features a complicated 3D network composed of 2D double layers of lead(II) sulfoisophthalate bridged by 1D chains of lead(II) arsonates along b-axis, forming large tunnels along b-axis which are occupied by phenyl rings of the arsonate ligands. In 2, the Pb(II) ions are bridged by {L²}^3- anions into a 2D double layer whereas the interconnection of the Pb(II) ions via bridging and chelating SIP anions gave a 2D double layer. The cross-linkage of the above two building units leads to a complicated 3D network. In 3, the interconnection of the Pb(II) ions via bridging {H₂L²}^- and {H₂BTC}^- anions leads to a 1D double chain down a-axis. These 1D chains are further interconnected via hydrogen bonds among non-coordination carboxylate groups and arsonate oxygens into a 3D supramolecular architecture.

Full text of DOI:10.1016/j.jssc.2008.03.002

ARTICLE IN PRESS
Journal of Solid State Chemistry 181 (2008) 1393– 1401
Contents lists available at ScienceDirect
Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
Novel lead(II) carboxylate– arsonate hybrids
Ã
Fei-Yan Yi, Jun-Ling Song, Na Zhao, Jiang-Gao Mao
State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, The Chinese Academy of Sciences, Fuzhou 350002, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Hydrothermal reactions of lead(II) acetate with phenylarsonic acid (H2L1) (or 4-hydroxy-3-nitropheny-
larsonic acid, H3L2) and 5-sulfoisophthalic acid monosodium salt (NaH2SIP) (or 1,3,5-benzenetricarboxylic
acid (H3BTC)) as the second metal linkers afforded three novel mixed-ligand lead(II) carboxylate–arsonates,
namely, Pb5(SIP)2(L1)2(H2O) 1, Pb3(SIP)(L2)(H2O) 2 and Pb(H2L2)(H2BTC) 3. The structure of 1 features a
complicated 3D network composed of 2D double layers of lead(II) sulfoisophthalate bridged by 1D chains of
lead(II) arsonates along b-axis, forming large tunnels along b-axis which are occupied by phenyl rings of the
arsonate ligands. In 2, the Pb(II) ions are bridged by {L2}3ꢀ anions into a 2D double layer whereas the
interconnection of the Pb(II) ions via bridging and chelating SIP anions gave a 2D double layer. The cross-
linkage of the above two building units leads to a complicated 3D network. In 3, the interconnection of the
Pb(II) ions via bridging {H2L2}ꢀ and {H2BTC}ꢀ anions leads to a 1D double chain down a-axis. These 1D
chains are further interconnected via hydrogen bonds among non-coordination carboxylate groups and
arsonate oxygens into a 3D supramolecular architecture.
Received 21 December 2007
Received in revised form
5 March 2008
Accepted 9 March 2008
Available online 16 March 2008
Keywords:
Metal arsonates
Inorganic–organic hybrids
Hydrothermal reactions
Open frameworks
Crystal structures.
& 2008 Elsevier Inc. All rights reserved.
1. Introduction
{Ph6As6O14}
4ꢀ, in addition to the unusual {V2O3}4+ cluster [37], and
the structure of another vanadium compound, V2O4(PhAsO3H) ꢁ
H2O, features a vanadium oxide layer with the arsonate ligand
hanging in the interlayer space [38]. In a gallium compound, two
PhAsO23ꢀ ligands were also condensed into a dimeric {Ph2As2O5}2ꢀ
anion, which bridges with two Ga(III) ions and forms a four-
member ring [39]. So far no lead(II) arsonates has been reported. As
a logical expansion of our previous works on lead(II) phosphonates,
we wish to design open frameworks of lead(II) arsonates by
applying a second metal linker, such method has been found to be
very effective to design 3D networks of lead(II) phosphonates
[40–42]. We selected phenylarsonic acid (H2L1) (or 4-hydroxy-3-
nitrophenylarsonic acid with two additional function groups, H3L2)
as the arsonate ligand and 5-sulfoisophthalic acid monosodium salt
(NaH2SIP) (or 1,3,5-benzenetricarboxylic acid (H3BTC)) as the
second metal linker. Hydrothermal reactions of the above two
types of ligands with lead (II) acetate resulted in three novel lead(II)
arsonates with novel 3D network structures or 3D supramolecular
assembly, namely, Pb5(SIP)2(L1)2(H2O) (1), Pb3(SIP)(L2)(H2O) (2)
and Pb(H2L2)(H2BTC) (3). Herein we report their syntheses, crystal
structures and characterizations.
The chemistry of metal phosphonates has been an active
research area in recent years due to its potential applications in
the areas of catalysis, ion exchange, proton conductivity, intercala-
tion chemistry, photochemistry and magnetic materials chemistry
[1–4]. In order to design metal phosphonates with open-frame-
works, a variety of functional groups such as amino acids, crown
ethers, amino groups and carboxylates have been attached to the
phosphonate groups [5–22]. Furthermore, the introduction of a
second ligand such as 4,40-bipy and oxalate anion has been proved
to be an effective synthetic method, since these second metal
linkers can act as pillars to link neighboring layers or be
incorporated into the inorganic layer to form a new hybrid layered
architecture [5–22]. Metal arsonates are expected to display a
similar structural chemistry to those of metal phosphonates, but
the larger ionic radius of As(V) could lead to some different
architectures with different physical properties. So far, reports on
metal arsonates are rather scarce [23–39]. A variety of polyox-
ometalate (POM) clusters of vanadium, molybdenum and tungsten
have been reported [23–36], in which each arsonate group bridges
with several metal centers as the phosphonate group in metal
phosphonates containing POM clusters [20]. It is interesting that
during the investigations of the V/O/PhAsO23ꢀ system the con-
densation of arsonate ligand gave a new hexadentate ligand,
2. Experimental section
2.1. Materials and methods
Ã
All chemicals were obtained from commercial sources and
used without further purification. Elemental analyses were
Corresponding author. Fax: +86 59183714946.
E-mail address: mjg@fjirsm.ac.cn (J.-G Mao).
0022-4596/$ - see front matter & 2008 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2008.03.002

ARTICLE IN PRESS
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F.-Y Yi et al. / Journal of Solid State Chemistry 181 (2008) 1393–1401
performed on a German Elementary Vario EL III instrument. The
FT-IR spectra were recorded on a Nicolet Magna 750 FT-IR
2.3. Single-crystal structure determination
spectrometer using KBr pellets in the range of 4000–400 cmꢀ1
.
Single crystals of compounds 1–3 were mounted on either a
Rigaku Mercury CCD diffractometer (for 1 and 2) or a Siemens
Smart CCD (for 3), both equipped with a graphite-monochro-
Thermogravimetric analyses were carried out on a NETZSCH STA
449C unit at a heating rate of 10 1C/min under a nitrogen
atmosphere. Photoluminescence analyses were performed on a
Perkin-Elemer LS55 fluorescence spectrometer. X-ray powder
diffraction (XRD) patterns (CuKa) were collected on a XPERT-
MPD yꢀ2y diffractometer.
˚
mated MoKa radiation (l ¼ 0.71073 A). Intensity data were
collected by the narrow frame method at 293 K. The data sets
were corrected for Lorentz and Polarization factors as well as for
absorption by a multi-scan method (for 1 and 2) or c-scan
technique (for 3) [43]. All three structures were solved by the
direct methods and refined by full-matrix least-squares fitting on
F2 by SHELX-97 [44]. All non-hydrogen atoms except O(1w) atoms
in 1 and 2 were refined with anisotropic thermal parameters.
C(21), C(22), C(23), C(24), C(25), C(26), C(32), C(33), C(35) and
C(36) of 1 are severely disordered and each has two orientations
with an occupancy factor of 50% for each site. Hydrogen atoms
excluding those for water molecules and those associated with the
disordered phenyl rings of the arsonate ligands in compound 1
were located at geometrically calculated positions and refined
with isotropical thermal parameters. Crystallographic data and
structural refinements for compounds 1–3 are summarized in
Table 1. Important bond lengths are listed in Table 2.
2.2. Synthesis of Pb5(SIP)2(L1)2(H2O) (1), Pb3(SIP)(L2)(H2O) (2) and
Pb(H2L2)(H2BTC) (3)
The three compounds were synthesized in a similar procedure.
A mixture of Pb(CH3COO)2 ꢁ 3H2O (0.23 g, 0.6 mmol), H2L1 (0.04 g,
0.2 mmol) or H3L2 (0.05 g, 0.2 mmol), 5-sulfoisophalic acid mono-
sodium salt (NaH2SIP) (0.11 g, 0.4 mmol) or H3BTC (0.08 g,
0.4 mmol) in 10 mL of deionized water, were put into a Parr
Teflon-lined autoclave (23 mL), and heated at 180 1C for 5 days.
The initial and final pH values of solution are 3.5 and 4.0 for 1 and
2, and 2.5 and 3.0 for 3, respectively. Crystals of compounds 1–3
were collected in a ca. 76% yield (based on L1, 0.15 g), 26% yield
((based on Pb, 0.059 g), and 38% yield (based on L2, 0.052 g)
respectively. Their purity has also confirmed by XRD powder
diffraction (see Supporting Materials). Anal. Calcd. for
CCDC-666407-666409 (for 1–3) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Center
via www.ccdc.cam.ac.uk/data_request/cif.
C
28H16O21S2As2Pb5 (Mr ¼ 1938.32): C, 16.85; H, 2.04. Found: C,
17.35; H, 0.83. IR data (KBr, cmꢀ1): 3434 (m), 1599 (m), 1523 (s),
1439 (m), 1363 (s), 1199 (s), 1109 (m), 1045 (m), 829 (m), 777 (m),
3. Results and discussion
723 (m), 614 (m). Anal. Calcd. for
C14H8NO14SAsPb3
3.1. Structure description for Pb5(SIP)2(L1)2(H2O) (1)
(Mr ¼ 1142.76): C, 14.07; H, 1.61; N, 1.26. Found: C, 14.71; H,
0.71. N, 1.23. IR data (KBr, cmꢀ1): 3434 (s), 1599 (s), 1523 (m), 1432
(m), 1355 (s), 1234 (m), 1168 (m), 1102 (w), 1035 (m), 795 (m), 718
(w), 618 (w). Anal. Calcd. for C15H10NO12AsPb (Mr ¼ 678.35): C,
26.16; H, 2.12; N, 2.03. Found: C, 26.56; H, 1.49; N, 2.06. IR data
(KBr, cmꢀ1): 3431 (m), 3283 (m), 3138 (m), 3071 (m), 1704 (vs),
1653 (m), 1612 (vs), 1528 (s), 1359 (m), 1247 (s), 1163 (m), 1091
(m), 909 (s), 895 (m), 838 (vs), 727 (m), 710 (m), 691 (m), 543 (m).
The structure of 1 features a complicated 3D network. As
shown in Fig. 1, there are five unique Pb(II) ions in its asymmetric
unit. They display different coordinated geometries (Fig. 2) Pb(1)
is five-coordinated by one sulfonate oxygen and four carboxylate
oxygen atoms from four SIP anions. Pb(2) is five-coordinated by
one sulfonate oxygen, three carboxylate oxygen atoms from three
Table 1
Summary of crystal data and structure refinements for 1– 3
1
2
3
Empirical formula
Formula weight
Crystal system
Space group
C28H16As2O21Pb5S2
1938.32
C14H8AsNO14Pb3S
1142.76
C15H10NO12AsPb
678.35
Monoclinic
C2/c
Monoclinic
P21/n
Triclinic
Pꢀ1
Crystal size (mm)
0.30 ꢂ 0.10 ꢂ 0.03
35.12(1)
0.3 ꢂ 0.25 ꢂ 0.05
11.1241(7)
10.5933(8)
17.826(1)
90.000
0.2 ꢂ 0.2 ꢂ 0.2
5.126(1)
11.8894(3)
14.8166(2)
98.83(1)
94.60(1)
98.12(1)
878.62(3)
2
˚
a (A)
˚
b (A)
10.522(4)
22.847(9)
90.000
˚
c (A)
a (deg)
b (deg)
118.251(1)
90.000
100.865(4)
90.000
g (deg)
3
˚
V (A )
7435.9(4)
8
2062.9(3)
4
Z
Dcalcd (g cmꢀ3)
3.463
3.679
2.564
m (mmꢀ1
F(000)
)
24.532
26.19
11.54
6880
2024
636.0
Reflections collected
Unique reflections
Observed data [I42s(I)]
GOF on F2
R1, wR2 [I42s(I)]a
R1, wR2 (all data)
28143
15508
4947
8518 [Rint ¼ 0.0607]
7076
4710 [Rint ¼ 0.0766]
3584
3268 [Rint ¼ 0.0921]
3147
0.995
0.946
1.199
0.0347, 0.0685
0.0459, 0.0730
0.0430, 0.0964
0.0518, 0.0991
0.0631, 0.1641
0.0655, 0.1661
P
P
P
P
a
R1
¼
||Fo|–|Fc||/ |Fo|, wR2 ¼ { w[(Fo)2–(Fc)2]2/ w[(Fo)2]2}1/2
.

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F.-Y Yi et al. / Journal of Solid State Chemistry 181 (2008) 1393–1401
1395
Table 2
f). The SIP anion containing S(1) atom is pentadentate and
connects with four lead(II) ions: one carboxylate group forms a
bidentate chelation with one lead(II) ion and the other carboxylate
group bridges with two Pb(II) ions (Scheme 1e). The SIP anion
containing S(2) atom acts as a heptadentate ligand and bridges
with six lead(II) ions, one carboxylate group is bidentate bridging
whereas the other one is tridentate chelating and bridging. Two
sulfonate oxygens are unidentate whereas the third one remains
non-coordinated (Scheme 1f). Both types of coordination modes
are different from that in Pb(BTS)(OH)(H2O) with a pillared
layered structure, in which both carboxylate groups are tridentate
chelating and bridging whereas the sulfonate group is bidentate
bridging [45]. The Pb–O distances range from 2.240(2) to
˚
Selected bond lengths (A) for compounds 1– 3
Compound 1
Pb(1)–O(6)
2.491(2)
2.526(2)
2.586(3)
2.411(2)
Pb(1)–O(2)#1
Pb(1)–O(9)
2.558(2)
Pb(1)–O(8)
2.562(2)
Pb(1)–O(4)#2
Pb(2)–O(10)
Pb(2)–O(2)
Pb(2)–O(1)
2.403(1)
Pb(2)–O(14)#3
Pb(2)–O(1W)
Pb(3)–O(3)
2.524(2)
2.697(2)
2.240(2)
2.3767(18)
2.2694(17)
2.4760(19)
2.7405(19)
2.298(2)
2.414(2)
2.640(2)
Pb(3)–O(15)
Pb(3)–O(17)#4
Pb(4)–O(18)#5
Pb(4)–O(11)#6
Pb(4)–O(19)
Pb(5)–O(16)
Pb(5)–O(19)
As(1)–O(16)
As(2)–O(18)
As(2)–O(20)
S(1)–O(6)
2.4233(15)
2.7406(16)
2.479(2)
Pb(3)–O(19)
Pb(4)–O(20)
Pb(4)–O(7)#3
Pb(5)–O(20)#5
Pb(5)–O(17)#4
As(1)–O(15)
As(1)–O(17)
As(2)–O(19)
S(1)–O(5)
2.6479(19)
2.4303(16)
2.7148(14)
1.6809(18)
1.687(2)
˚
2.741(2) A (Table 2), which are comparable to those reported for
1.6799(19)
1.668(2)
1.683(2)
1.444(2)
1.455(3)
1.471(3)
1.6998(19)
1.448(3)
other Pb(II) phosphonates and Pb(II) carboxylates [40–42].
The interconnection of Pb(3), Pb(4) and Pb(5) atoms by the
bridging phenylarsonic ligands groups resulted in a 1D chains
(Fig. 3a). The interconnection of the Pb(1), Pb(2), Pb(3) and Pb(4)
atoms by bridging and chelating SIP anions leads to a 2D layer
(Fig. 3b). It is reported that in lead(II) complex with BTS and
3-Pyridyl-CH2NH(CH2PO3H2)2, the lead(II) ions also form a 2D
layer motif with BTS anions, whereas in the lead(II) complex with
BTS and N-(phosphonomethyl)-N-methylglycine, the lead(II) ions
are bridged by BTS anions into a 1D chain [46]. The cross-linkage
of the above two building blocks afforded to a complicated 3D
network with large tunnels along b-axis, the phenyl rings of the
arsonate ligands are located at these tunnels (Fig. 4).
S(1)–O(7)
1.452(3)
S(2)–O(12)
S(2)–O(13)
1.452(3)
S(2)–O(14)
Compound 2
Pb(1)–O(2)
Pb(1)–O(11)
Pb(2)–O(7)#3
Pb(2)–O(1)
Pb(2)–O(3)#5
Pb(3)–O(3)#5
Pb(3)–O(1)
Pb(3)–O(1w)
As(1)–O(2)
S(1)–O(7)
2.214(7)
2.330(7)
2.291(7)
2.405(7)
2.680(7)
2.315(7)
2.390(7)
2.866(7)
1.680(8)
1.433(8)
1.439(8)
Pb(1)–O(10)#1
Pb(1)–O(12)#2
Pb(2)–O(14)#4
Pb(2)–O(4)#3
Pb(2)–O(9)#6
Pb(3)–O(13)#7
Pb(3)–O(14)#7
As(1)–O(3)
2.521(8)
2.566(7)
2.457(7)
2.561(8)
2.685(8)
2.446(7)
2.742(6)
1.666(7)
1.687(7)
1.455(8)
As(1)–O(1)
S(1)–O(8)
S(1)–O(9)
3.2. Structure description for Pb3(SIP)(L2)(H2O) (2)
Compound 3
Pb(1)–O(12)#1
Pb(1)–O(11)#2
Pb(1)–O(6)
2.32(1)
2.37(1)
2.56(1)
1.67(1)
1.32(2)
1.31(2)
1.26(2)
Pb(1)–O(11)
Pb(1)–O(7)
As(1)–O(12)
As(1)–O(13)
C(13)–O(9)
C(14)–O(5)
C(15)–O(7)
2.67(1)
2.72(1)
1.64(1)
1.73(1)
1.22(2)
1.25(2)
1.27(2)
As shown in Fig. 5, the formula unit of 2 contains three Pb(II)
ions, one fully deprotonated {L2}3ꢀ anion, and one fully deproto-
nated SIP3ꢀ anion and one aqua ligand. The three unique Pb(II)
ions exhibit different coordinated geometries (Fig. 6). Pb(1) is
four-coordinated by one sulfonate and two carboxylate oxygen
atoms from three SIP anions as well as an arsonate oxygen atom
from a {L2}3ꢀ anion, its coordination geometry can be described as
a c-PbO4 trigonal bipyramid with one corner filled by the lone
pair electrons. Pb(3) is four-coordinated by a bidentate chelating
carboxylate group of a BTS3ꢀ anion, two arsonate oxygens from
two {L2}3ꢀ anions and an aqua ligand, its coordination geometry
can be described as a c-PbO4 distorted square pyramid with the
pyramidal site filled by the lone pair electrons (Fig. 6). Pb(2) is six-
coordinated by one carboxylate and one sulfonate oxygen atoms
from two SIP anions, two arsonate oxygen atoms, one nitro oxygen
atom and one hydroxyl group from three {L2}3ꢀ anions in a
severely distorted octahedral geometry. The Pb(3)–O(1w) distance
As(1)–O(11)
C(13)–O(8)
C(14)–O(4)
C(15)–O(6)
Hydrogen bonds
O(4)?O(5)#3
O(3)?O(1)
2.60(2)
2.58(2)
O(13)?O(9)#4
2.66(1)
Symmetry transformations used to generate equivalent atoms: for 1: #1 ꢀx+3/2,
ꢀy+3/2, ꢀz+1; #2 x, y+1, z; #3 x, yꢀ1, z; #4 ꢀx+1, ꢀy, ꢀz+1; #5 ꢀx+1, ꢀyꢀ1, ꢀz+1;
#6 x, ꢀy, z+1/2. For 2: #1 ꢀx+1/2, yꢀ1/2, ꢀz+1/2; #2 ꢀx+1, ꢀy, ꢀz+1; #3 ꢀx+2, ꢀy,
ꢀz+1; #4 x+1/2, ꢀy+1/2, zꢀ1/2; #5 ꢀx+3/2, y+1/2, ꢀz+1/2; #6 ꢀx+3/2, yꢀ1/2,
ꢀz+1/2; #7 ꢀx+1, ꢀy+1, ꢀz+1. For 3: #1 xꢀ1, y, z; #2 ꢀx+1, ꢀy, ꢀz+1; #3 ꢀxꢀ1,
ꢀy+1, ꢀz+2; #4 x+1, y, zꢀ1.
SIP3ꢀ anions and an aqua ligand. Pb(4) is five-coordinated by one
carboxylate oxygen, one sulfonate oxygen atom from two SIP3ꢀ
anions and three arsonate oxygen atoms from two {L1}2ꢀ anions.
The coordination geometry around Pb(1), Pb(2) and Pb(4) can be
described as a severely distorted c-PbO5 octahedron with one site
occupied by the lone pair electrons. Pb(3) is four-coordinated by
three arsonate oxygen atoms from three {L1}2ꢀ anions and one
oxygen atom from a SIP3ꢀ anion. Pb(5) is also four-coordinated
but by four arsonate oxygen atoms from four {L1}2ꢀ anions. The
coordination geometry around Pb(3) and Pb(5) can be described
as a severely distorted c-PbO4 trigonal bipyramid with one site
occupied by the lone pair electrons. The two phenylarsonate
anions display two different coordination modes (Scheme 1a and b).
The one containing As(1) atom is tetradentate and bridges with
four lead(II) ions, O(17) is m2-bridging whereas O(15) and O(16)
are unidentate. The one containing As(2) atom is hexadentate and
connects with six lead(II) ions: O(19) is m3-bridging, O(20) is m2-
bridging whereas O(18) is unidentate. The two SIP3ꢀ anions also
exhibit two different types of coordination modes (Scheme 1e and
˚
of 2.866(7) A is significantly longer than those of the remaining
˚
Pb–O bonds (2.214(7)–2.742(6) A) (Table 2), hence it can be
considered as a weak coordination bond. The {L2}3ꢀ anion is
heptadentate and connects with six lead(II) ions: two arsonate
oxygens are bidentate whereas the third one is unidentate, the
hydroxyl group and one nitro oxygen form
a six-member
chelation ring with a lead(II) ion, the other nitro oxygen remains
non-coordinated (Scheme 1c). The SIP3ꢀ anion is heptadentate
and bridges with six lead(II) ions: one carboxylate group chelates
bidentately with a Pb(II) ion and also bridges with another Pb(II)
ion whereas the other carboxylate group bridges with two Pb(II)
ions. The sulfonate group bridges with two Pb(II) ions by using
two oxygen atoms and the third sulfonate oxygen atom remains
non-coordinated (Scheme 1e). Such coordination mode has also
been observed in 1.
The interconnection of the lead(II) ions via bridging and
chelating {L2}3ꢀ anions resulted in the formation of a (ꢀ202)
layer (Fig. 7a). The interconnection of the Pb(II) ions via bridging

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F.-Y Yi et al. / Journal of Solid State Chemistry 181 (2008) 1393–1401
Fig. 1. ORTEP representation of the selected unit in compound 1. The thermal ellipsoids are drawn at 50% probability level. Only one orientation was shown for the
disordered carbon atoms of phenylarsonic acid ligands for clarity. Symmetry codes for the generated atoms: (a) ꢀx+3/2, ꢀy+3/2, ꢀz+1; (b) x, y+1, z; (c) x, yꢀ1, z; (d) ꢀx+1,
ꢀy, ꢀz+1; (e) ꢀx+1, ꢀyꢀ1, ꢀz+1; (f) x, ꢀy, z+1/2; and (g) x, ꢀy, zꢀ1/2.
protonated: the hydroxyl group and one oxygen atom of the
arsonate group. Based on As–O distances, O(13) is most likely
protonated. The {H2L2}ꢀ anion is tridentate: the arsonate group
bridges with three Pb(II) ions by using two oxygen atoms and the
third oxygen atom remains non-coordinated. The nitro group and
hydroxyl groups are also non-coordinated (Scheme 1d). The
tricarboxylate ligand is also doubly protonated, O(4) and O(8)
atoms are most likely protonated based on C–O distances
(Table 2). The {H2BTC}ꢀ anion is bidentate chelating with a Pb(II)
ion by using one carboxylate group, the other two protonated
carboxylate groups remain non-coordinated (Scheme 1g). Such kind
of coordination mode has also been reported in the layered mixed-
ligand lead(II) complex containing both N-cyclohexylimino-bis
(methylene-phosphonic acid) and BTC, in which additional neutral
H3BTC molecule act as the interlayer intercalated species [40]. In
layered Pb3(BTC)2.H2O, the BTC anions adopt three types of multi-
dentate coordination modes in which all carboxylate groups are
Fig. 2. Coordination geometries around the Pb(II) ions in compound 1.
chelating and bridging [47].
The interconnection of the Pb(II) ions via bridging arsonate
groups of the {H2L2}ꢀ anions leads to a 1D double chain along
b-axis (Fig. 10). The {H2BTC}ꢀ anions are hanging on the above
chains. Within the 1D chain, hydrogen bonds are formed between
hydroxyl groups and nitro groups of the arsonate ligands
and chelating SIP anions leads to a (ꢀ101) Pb(II) carboxylate–
sulfonate layer (Fig. 7b). The cross-linkage of the above two
building units gave a complicated 3D network (Fig. 8). Such 3D
network can also be viewed as the lead(II) arsonate–sulfonate
inorganic layers passing 1/4 and 3/4 of c-axis being bridged by
organic groups of the above two types of multi-dentate ligands.
There are also p?p interactions between neighboring phenyl
rings of arsonate or BTS ligands. These phenyl rings are parallel to
˚
(O(3)–H(7b)?O(1)) (Fig. 10). The O?O separate is 2.58(2) A and
the hydrogen bond angle is 139.51. These 1D chains are further
interlinked via hydrogen bonds among non-coordination carbox-
ylate groups and non-coordinate arsonate oxygens into a 3D
supramolecular assembly (Fig. 11). The O(4)?O(5) (symmetry
operator: ꢀxꢀ1, ꢀy+1, ꢀz+2) and O(13)?O(9) (symmetry opera-
˚
each other and have inter-ring distances of 3.448 and 3.644 A,
respectively. These p?p interactions further stabilize the frame-
work of the structure.
˚
tor: x+1, y, zꢀ1) separations are 2.60(2) and 2.66(1) A (Table 2),
respectively and the corresponding hydrogen bond angles are
174.41 and 178.81, respectively. Hence the 3D supramolecular
assembly of 3 is expected to be quite stable due to these strong
hydrogen bonds.
3.3. Structure description for Pb(H2L2)(H2BTC) (3)
The measured XRD powder patterns of compounds 1–3 match
with the ones simulated from their single crystal structure data,
thus all three compounds can be obtained as single phases (See
Supporting Materials).
The asymmetric unit of 3 contains one lead(II) ion, one doubly
protonated {H2L2}ꢀ anion and one doubly protonated {H2BTC}ꢀ
anion. As shown in Fig. 9, the lead(II) is five-coordinated by a
bidentate chelating carboxylate group of a {H2BTC}ꢀ anion and
three arsonate oxygens from three {H2L2}ꢀ anions. Its coordina-
tion geometry can be described as a severely distorted c-PbO5
octahedron with the lone pair of the lead (II) ion occupying the
sixth site. The Pb–O bond distances are in the range of
3.4. IR, luminescence properties and TGA studies for compound 1– 3
The FT-IR spectra of all of the three compounds show the
typical u (As ¼ O) [33] stretching vibration bands (1109 cmꢀ1 for 1,
1101 cmꢀ1 for 2 and 1091 cmꢀ1 for 3). Compounds 1 and 2 exhibit
˚
2.32(1)–2.72(1) A (Table 2), which are comparable to those
reported in compounds 1 and 2. The arsonate ligand is doubly

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Scheme 1. Coordination modes of H2L1, H3L2, NaH2SIP, H3BTC ligands in compounds 1–3.
Fig. 4. View of the structure of compound 1 down the b-axis. The CAsO3 and CSO3
tetrahedra are shaded in medium and light gray, respectively. Pb, C and O atoms
are represented by open, black and crossed circles, respectively.
at 1523 cmꢀ1, and 1432 and 1355 cmꢀ1 for compound 2, at
1704 cmꢀ1, and 1612 and 1528 cmꢀ1 for compound 3, respectively,
correspond to the asymmetric and symmetric stretching bands of
the carboxylate groups [48].
Photoluminescent properties of s2-metal complexes are not
well studied as compared with those of d10-metal complexes,
although there are reports on the photoluminescent properties of
lead-containing materials [49,50]. The solid-state luminescence
properties of compounds 1–3 as well as two free arsonate ligands
and two second metal linkers were investigated at room
temperature. The free phenylarsonic acid ligand exhibits two
fluorescent emission bands at lmax ¼ 323, 368 nm upon excitation
at 242 nm whereas the 5-sulfoisophthalic acid monosodium salt
Fig. 3. 1D chains of lead(II) arsonate along b-axis (a) and a double 2D layer of Pb(II)
carboxylate-sulfonate in 1. The CAsO3 and CSO3 tetrahedra are shaded in medium
and light gray, respectively. Pb, C and O atoms are represented by open, black and
crossed circles, respectively.
(NaH2SIP) ligand displays
a fluorescent emission band at
broad, strong absorptions centered at 3434 cmꢀ1 for both 1 and 2,
occurring because of the existence of water molecules in the
structures. The absorptions in the region 1000–1200 cmꢀ1 for 1
and 2 are typical of the sulfonate group. The strong absorption
bands at 1199 and 1168 cmꢀ1 for compounds 1 and 2, respectively,
are because of the usꢀo stretching [48]. The IR spectrum of 1 shows
the typical asymmetric (1523 cmꢀ1) and symmetric (1439 and
1363 cmꢀ1). And the compounds 2 and 3 also exhibit strong bands
lmax ¼ 327 nm upon excitation at 260 nm [51]. Compound 1
displays two strong broad emission bands at lmax ¼ 376, 414 nm
(lex ¼ 237 nm) upon complexion of both L1 ligands and SIP ligands
with the Pb(II) ions. The free 4-hydroxy-3-nitrophenylarsonic acid
ligand displays a fluorescent emission band at lmax ¼ 421 nm with
a shoulder at 482 nm upon excitation at 237 nm (Fig. 12a).
Compound 2 displays a strong fluorescent emission band at
lmax ¼ 356 nm (lex ¼ 213 nm) upon complexion of the L2 ligands

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Fig. 5. ORTEP representation of the selected unit of compound 2. Thermal
ellipsoids are drawn at 50% probability level. Symmetry codes for the generated
atoms: (a) ꢀx+1/2, yꢀ1/2, ꢀz+1/2; (b) ꢀx+1, ꢀy, ꢀz+1; (c) ꢀx+2, ꢀy, ꢀz+1; (d) x+1/
2, ꢀy+1/2, zꢀ1/2; (e) ꢀx+3/2, y+1/2, ꢀz+1/2; (f) ꢀx+3/2, yꢀ1/2, ꢀz+1/2; (g) ꢀx+1,
ꢀy+1, ꢀz+1; (h) 1/2ꢀx, 1/2+y, 1/2ꢀz; and (i) xꢀ1/2, ꢀy+1/2, z+1/2.
Fig. 6. Coordination geometries around the lead(II) ions in compound 2.
and SIP ligands with the Pb(II) ions. The H3BTC exhibits a
fluorescent emission band at lmax ¼ 355 nm upon excitation at
260 nm (Fig. 12b). Compound 3 displays a strong fluorescent
emission band at lmax ¼ 418 nm (lex ¼ 237 nm) and a weak
fluorescent emission band at lmax ¼ 481 nm (lex ¼ 237 nm) upon
complexion of the L2 ligands and H2BTC ligands with the PbII ions
(Fig. 12c). These emission bands are neither metal-to-ligand
charge transfer (MLCT) nor ligand-to-metal charge transfer
(LMCT) in nature, but rather can be attributed to an intraligand
emission state [40–42].
The TGA curves of compound 1 exhibit two main steps of
weight losses (Fig. 13). The first weight loss began at 100 1C and
completed at 238 1C, which corresponds to the loss of an aqua
ligand per formula unit, the weight loss of 0.94% is in good
agreement with the calculated value of 0.93% (Fig. 13). The second
step covering a temperature range of 412–554 1C corresponds to
the combustion of SIP and phenylarsonic ligands. The total
observed weight loss at 500 1C is 31.8%. If we assume the final
residues are Pb3(AsO3)2 and PbO in a molar ratio of 1:2, the
calculated total weight loss is 32.3%. The TGA curses of compound
2 shows one main continuous step of weight losses. The weight
loss began at 253 1C and completed at 491 1C, which corresponds
to the combustion of SIP and phenylarsonic ligands. The final
products are assumed to be Pb3(AsO3)2 and PbO in a 1:3 molar
ratio. The total observed weight loss at 700 1C is 27.9% is close to
the calculated value (32.7%). The TGA curves of compound 3
shows one main step of weight losses. The weight loss began at
272 1C and completed at 529 1C, which corresponds to combustion
of tricarboxylate and 3-nitro-4-hydroxyl-phenylarsonic ligands.
Fig. 7. A (ꢀ202) 2D double layer of lead arsonate (a) and a (ꢀ101) 2D layer of lead
(II) carboxylate-sulfonate in 2 (b). The CAsO3 and CSO3 tetrahedra are shaded in
medium and light gray, respectively. Pb, C and O atoms are represented by open,
black and crossed circles, respectively.
The final residuals are assumed to be Pb3(AsO3)2 and As2O3 in a
2:1 molar ratio. The total observed weight loss of 55.6% at 700 1C
is close to the calculated one (52.6%) [23,24,49,52].
4. Conclusion
In summary, hydrothermal reactions of Pb(II) acetate with H2L1
or H3L2 and 5-sulfoisophalic acid monosodium salt (NaH2SIP) or
1,3,5-benzenetricarboxylic acid (H3BTC) as the second metal
linker afforded three new Pb(II) carboxylate–arsonate hybrids.
The substitute groups on the arsonate ligands have strong effects
on the structures of resultant compounds when they provide
additional coordination atoms. Furthermore the nature of the
second ligand with the metal ion is also very important. Results of
our studies indicate that inorganic–organic hybrids of metal
arsonates with various types of structures can be developed by
using the same technique applied in the metal phosphonate
systems. It is believed that a wide range of other new metal
arsonates such as luminescent lanthanide arsonates and transition

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metal arsonates can be obtained by using such synthetic technique
and currently we are exploring these possibilities.
Acknowledgments
This work was supported by the National Natural Science
Foundation of China (Nos. 20371047), the NSF of Fujian Province
(E0610034), Key Project of the Chinese Academy of Sciences (No.
KJCX2-YW-H01) and 973 Program (No. 2006CB932903).
Fig. 10. A 1D lead(II) carboxylate–arsonate double chain in compound 3 along the
a-axis. The CAsO3 are shaded in gray. Pb, C, and O atoms are represented by open,
black and crossed circles, respectively.
Fig. 8. View of the structure of compound 2 down the b-axis. The CAsO3 and CSO3
tetrahedra are shaded in medium and light gray, respectively. Pb, C and O atoms
are represented by open, black and crossed circles, respectively.
Fig. 11. View of the structure of compound 3 down the a-axis. The CAsO3 are
shaded in pink. Pb, C, and O atoms are represented by open, black and crossed
circles, respectively.
Fig. 9. ORTEP representation of the selected unit of compound 3. Thermal ellipsoids are drawn at 50% probability. Symmetry codes for the generated atoms: (a) xꢀ1, y, z; (b)
ꢀx+1, ꢀy, ꢀz+1; (c) x+1, y, z; (d) ꢀxꢀ1, ꢀy+1, ꢀz+2; (e) x+1, y, zꢀ1. Hydrogen bonds are drawn as dashed lines.

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Fig. 12. Solid-state emission spectra of compounds 1 (a), 2 (b) and 3 (c).
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