New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: Syntheses, structures, and luminescent properties

Article abstract of DOI:10.1021/ic201589p

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH₄)·[Ag(HL1)(NH₃)(H ₂O)] (1), {(NH₄)·[Ag₃

Full text of DOI:10.1021/ic201589p

Article
pubs.acs.org/IC
New Family of Silver(I) Complexes Based on Hydroxyl and Carboxyl
Groups Decorated Arenesulfonic Acid: Syntheses, Structures, and
Luminescent Properties
Xiang-Qian Fang, Zhao-Peng Deng, Li-Hua Huo, Wang Wan, Zhi-Biao Zhu,* Hui Zhao, and Shan Gao*
Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Heilongjiang University, Harbin 150080,
People’s Republic of China
S
* Supporting Information
ABSTRACT: Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl
groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates,
(NH4)·[Ag(HL1)(NH3)(H2O)] (1), {(NH4)·[Ag3(HL1)2(NH3)(H2O)]}n (2),
[Ag2(HL1)(H2O)2]n (3), [Ag2(HL2)(NH3)2]·H2O (4), [Ag(H2L2)(H2O)]n (5),
[Ag2(HL2)]n (6), [Ag3(L3)(NH3)3]n (7), [Ag2(HL3)]n (8), and [Ag6(L3)2(H2O)3]n
(9) (H3L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H3L2 = 2-hydroxyl-4-
carboxylbenzenesulfonic acid, H3L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which
are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction.
Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH3)(H2O)]− anions
+
and NH4 cations. Complex 2 exhibits 3-D host−guest framework which encapsulates
ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from
1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)2(COO)2] binuclear units.
Complex 4 exhibits 3-D hydrogen-bonding host−guest network which encapsulates water
molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic
linker bridged 1-D Ag−O−S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure
constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of
complex 7 is formed by L3− trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared
layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O4)2(Ag2O5)2]∞
motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres
with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different
ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent
properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue
luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.
simple coordination modes.1 By contrast, only around 39 of the
INTRODUCTION
■
186 crystallographically characterized silver(I)-sulfonates11 are
Design and synthesis of silver(I)−sulfonates have been an
constructed from pure arenesulfonic acids. Significantly,
active research field in crystal engineering and coordination
although these 39 complexes feature alluring 0-D separated,1d,2
chemistry1−7 in view of their potential applications in the area
1-D columnar,1g,3 2-D layered,1e,4 and 3-D pillared layered5
of intercalation chemistry, photochemistry, and porous
silver(I)−sulfonate frameworks with prominent properties of
materials and fascinating structural diversities arising from the
fluorescent properties,1e,4e as well as intriguing selective and
reversible guest inclusion,4d the influence of the nature of
arenesulfonic acids on the solid structures and properties of
silver(I) complexes are relatively uncommon. Hence, it is still a
tempting challenge to synthesis silver(I)−sulfonates with
attractive structures and properties through the rational design
of pure arenesulfonic acids.
versatile coordination geometries of Ag(I) ion8 and diversiform
9
−
bridging modes of sulfonate (RSO3 ). Actually, the sulfonate
group is considered to be a weak ligand which is often
evidenced by its inability to replace solvent molecules from
the coordination spheres of many metal ions, and in many cases
it is only involved in hydrogen bonding supramolecular
networks.10 In order to modulate the binding modes and the
topological architectures of silver(I)-sulfonates, neutral
N-containing secondary ligands are employed, and many such
mixed-ligand silver(I)-sulfonates have been reported based
on Cambridge Structural Database CSD research (version
5.27).11 However, the structures are highly dependent on the
presence of N-containing secondary ligands, whereas the
sulfonates serve as either noncoordinating counteranions or
In this sense, decoration of arenesulfonic acids by attaching
additional functional groups such as carboxyl, hydroxyl, and
amine groups is another effective way to improve the
coordination abilities of sulfonate ligands.1e,g,4i In our previous
Received: July 24, 2011
Published: November 16, 2011
© 2011 American Chemical Society
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Inorganic Chemistry
Article
studies, we have demonstrate that the introduction of hydroxyl
groups at the ortho-position can effectively enrich the
coordination modes of the −SO3 group and modulate the
final topological structures of silver(I)-sulfonates.7 Moreover,
5-sulfosalicylic acid (H3SSA), a simple but interesting ligand
with three potential coordinating groups of −OH, −CO2H, and
−SO3H, can easily coordinate to metal ions with different
modes and lead to the formation of high-dimensional
architectures.4e,f,5a Consequently, three successors of H3SSA,
namely, 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid
(H3L1), 2-hydroxyl-4-carboxylbenzenesulfonic acid (H3L2),
and 2-hydroxyl-5-carboxylbenzenesulfonic acid (H3L3), have
been designed and exploited to construct novel topological
structures with excellent properties considering the following
points. (a) As versatile tectons, the three ligands contain the
same multifunctional groups, which may be partially or
completely deprotonated and normally serve as bridging
connector to construct diverse supramolecular aggregations or
coordination polymers via different coordination and/or
intermolecular forces. (b) In comparison with the para-position
of hydroxyl group in H3SSA, the hydroxyl groups at the ortho-
position of sulfonate groups can effectively enrich the
coordination modes and binding abilities of the −SO3 group
to modify the topological structures of silver(I)−sulfonates. (c)
The carboxyl group binds to Ag(I) ion in a variety of
coordination modes and thus affords the argentophilic
interactions, which have been proved to be one of the most
important factors contributing to the formation of Ag(I)
Table 1. Crystal Data and Structure Refinement Parameters of Complexes 1−9
1
2
3
4
empirical formula
Mr
C7H12N2O7SBrAg
456.03
C14H15N2O13S2Br2Ag3
966.83
C7H7O8SBrAg2
546.84
C14H24N4O14S2Ag4
967.97
cryst syst
space group
a/Å
triclinic
triclinic
triclinic
monoclinic
P21/c
P1
̅
P1
̅
P1
̅
7.5987(15)
9.4869(19)
9.5920(19)
93.83(3)
105.80(3)
94.93(3)
660.0(2)
2
9.4697(19)
10.256(2)
12.099(2)
87.90(3)
88.38(3)
81.24(3)
1160.3(4)
2
6.6639(13)
9.5487(19)
9.977(2)
84.26(3)
75.75(3)
86.71(3)
611.9(2)
2
13.257(3)
6.5426(13)
14.635(3)
90.00
b/Å
c/Å
α/deg
β/deg
104.98(3)
90.00
γ/deg
V/Å3
1226.2(4)
2
Z
Dc/mg m−3
μ/mm−1
2.295
2.767
2.968
2.622
4.742
6.201
6.667
3.395
θ range
3.05−27.46
6455
3.15−25.00
9165
3.14−27.45
6029
3.18−27.47
11 225
reflns collected
unique reflns
no. of params
F(000)
2973
4076
2769
2803
184
343
178
179
444
920
516
936
R1, wR2 [I > 2σ(I)]
GOF on F2
largest and hole/e·A−3
complex
0.0576, 0.1561
1.073
0.0361, 0.0999
1.090
0.0469, 0.1141
1.017
0.0727, 0.1799
1.036
1.644, −1.329
5
1.919, −1.128
1.987, −1.317
1.612, −1.596
9
6
7
8
empirical formula
Mr
C7H7O7SAg
C7H4O6SAg2
431.90
C7H12N3O6SAg3
589.87
C7H4O6SAg2
431.90
C14H12O15S2Ag6
1131.58
monoclinic
P21/c
343.06
cryst syst
space group
a/Å
monoclinic
C2/c
monoclinic
C2/c
triclinic
triclinic
P1
P1
̅
̅
20.417(4)
7.7642(16)
11.886(2)
90.00
19.227(4)
8.2824(17)
11.582(2)
90.00
6.2647(13)
8.3431(17)
12.831(3)
89.65(3)
80.19(3)
83.36(3)
656.4(2)
2
6.9889(14)
7.4711(15)
9.6405(19)
70.80(3)
85.46(3)
73.85(3)
456.6(2)
2
10.8102(4)
16.2514(5)
12.5666(4)
90.00
b/Å
c/Å
α/deg
β/deg
103.96(3)
90.00
106.27(3)
90.00
94.5590(10)
90.00
γ/deg
V/Å3
1828.6(6)
8
1770.5(6)
8
2200.73(13)
4
Z
Dc/mg m−3
μ/mm−1
2.492
3.241
2.985
3.142
3.415
2.452
4.668
4.618
4.525
5.504
θ range
3.19−27.45
8627
3.71−27.46
6565
3.22−27.48
6397
3.00−27.44
4502
3.14−27.46
21 060
reflns collected
unique reflns
no. of params
F(000)
2083
2021
2963
2062
5014
154
145
184
148
358
1344
1632
560
408
2120
R1, wR2 [I > 2σ(I)]
GOF on F2
largest and hole/e·A−3
0.0216, 0.0455
1.094
0.0446, 0.0875
1.005
0.0514, 0.1493
1.051
0.0310, 0.0758
1.086
0.0479, 0.1162
1.071
0.719, −0.678
0.880, −0.778
1.596, −1.816
1.573, −0.916
2.217, −1.221
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Inorganic Chemistry
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complexes and special properties.1e,12 As part of our long-term
ongoing research on the coordination chemistry of silver(I)−
sulfonates, we presented in this article the syntheses, structures and
luminescent properties of nine new complexes based on the above
three ligands and different silver(I) salts, namely, (NH4)·[Ag-
(HL1)(NH3)(H2O)] (1), {(NH4)·[Ag3(HL1)2(NH3)(H2O)]}n
(2), [Ag2(HL1)(H2O)2]n (3), [Ag2(HL2)(NH3)2]·H2O (4),
[Ag(H2L2)(H2O)]n (5), [Ag2(HL2)]n (6), [Ag3(L3)(NH3)3]n
(7), [Ag2(HL3)]n (8), and [Ag6(L3)2(H2O)3]n (9). Complexes 1
and 4 exhibit host−guest 3-D supramolecular networks extended
by the N/O−H···O hydrogen bonds. Complex 3 presents 2-D
layer structure constructed from 1-D tape of sulfonate-bridged Ag1
dimers linked by [(Ag2)2(COO)2] binuclear units. Complexes 2
and 5−9 exhibit 3-D host−guest, hybrid and pillared layered
frameworks, respectively. The structural diversities and evolutions
can be attributed to the synthetic methods, coordination modes
and different arenesulfonic acid ligands decorated by hydroxyl and
carboxyl groups. Luminescent investigations indicate that
complexes 1−3 and 5 exhibit strong blue emissions at room
temperature. Moreover, complex 1 can sensitize Tb(III) ion to
exhibit characteristic green emission at room temperature in
aqueous solution.
3278m, 3187s, 3073w, 1617m, 1581m, 1565m, 1425s, 1369m, 1267m,
1222m, 1191s, 1037s, 892m, 846m, 800m, 698m, 620s, 539m.
Synthesis of {(NH4)·[Ag3(HL1)2(NH3)(H2O)]}n (2). A similar proce-
dure with complex 1 was carried out. The pH value was adjusted to ∼7
with proper amount of ammonia. Pale-yellow crystals of 2 suitable for
X-ray diffraction were isolated from the filtrate after avoiding
illumination for several days. Yield: 58% (based on Ag). Anal. Calcd
for C14H15N2O13S2Br2Ag3: C 17.39, H 1.56, N 2.90%; found C 17.43,
H 1.52, N 2.93%. IR (ν/cm−1): 3439m, 3363m, 3178m, 3064w,
1614m, 1571m, 1427s, 1363m, 1268m, 1226m, 1157s, 1027s, 894m,
844m, 798m, 698m, 615s, 541m.
Synthesis of [Ag2(HL1)(H2O)2]n (3). An aqueous solution of H3L1
(0.298 g, 1.0 mmol) was added to an aqueous suspension containing
Ag2CO3 (0.276 g, 1.0 mmol). The mixture was stirred for 40 min until
no further CO2 was given off, and then filtered. The resulting clear
solution was allowed to evaporate slowly at room temperature after
avoiding illumination for two weeks, and pale-yellow crystals of 3
suitable for X-ray diffraction were isolated. Yield: 53% (based on Ag).
EXPERIMENTAL SECTION
■
General Procedures. All chemicals and solvents were of A. R.
grade and used without further purification for the syntheses.
Elemental analyses were carried out with a Vario MICRO from
Elementar Analysensysteme GmbH, and the infrared spectra (IR)
were recorded from KBr pellets in the range of 4000−400 cm−1 on
a Bruker Equinox 55 FT-IR spectrometer. Thermogravimetric analysis
(TGA) were performed on a Perkin-Elmer TG/DTA 6300 thermal
analyzer under flowing N2 atmosphere, with a heating rate of
10 °C/min. Luminescence spectra were measured on a Perkin-Elmer
LS 55 luminance meter. To examine the possibility of modification
of the luminescent properties through cation exchange, the solid
sample of complex 1 was immersed in aqueous solution (1 × 10−4
mol·L−1) containing the same amount of Eu3+ and Tb3+ ions,
respectively.
Syntheses of Ligands. 5-Bromo-2-hydroxybenzoic acid, 3-
hydroxybenzoic acid, and 4-hydroxybenzoic acid were slowly added
to different amounts of 20% oleum with stirring, respectively. The
mixture was left to react 3 h at 120 °C and then cooled to room
temperature. The laurel-green solids for H3L2 and white solids for
H3L1 and H3L3 were separated and recrystallized from hot water
(Figure S1 in Supporting Information). H3L1: yield 80%; mp 143−
145 °C. Elemental analysis calcd (%) for C7H5O6BrS: C 28.30, H 1.70;
found C 28.34, H 1.75. IR (ν/cm−1): 3413s, 3235m, 3043w, 1666s,
1617s, 1589s, 1527m, 1459m, 1378m, 1357m, 1309m, 1238m, 1191w,
1039w, 989w, 952m, 821m, 692m, 611m, 516m. H3L2: yield 82%; mp
230−232 °C. Elemental analysis calcd (%) for C7H6O6S: C 38.54, H
2.77; found C 38.59, H 2.83. IR (ν/cm−1): 3274m,br, 3068w, 1698s,
1589 m, 1508 m, 1417s, 1374m, 1295m, 1220s, 1193s, 1149m, 1083m,
1018s, 948m, 883m, 759m, 703m, 634m, 561m, 524m. For H3L3:
yield 85%; mp 242−244 °C. Elemental analysis calcd (%) for
C7H6O6S: C 38.54, H 2.77; found C 38.50, H 2.82. IR (ν/cm−1):
3234m,br, 3060w, 1685s, 1602s, 1508 m, 1407s, 1363w, 1290s, 1203m,
1155m, 1079m, 1018m, 919w, 887m, 846m, 769m, 728m, 626m,
578m.
Synthesis of (NH4)·[Ag(HL1)(NH3)(H2O)] (1). AgNO3 (0.255 g, 1.5
mmol) and H3L1 (0.149 g, 0.5 mmol) were mixed in 10 mL aqueous
solution, and then the pH value was adjusted to ∼6 with proper
amount of ammonia. The mixture stirred at room temperature for
5 min followed by filtration. Colorless crystals of 1 were isolated from
the filtrate after avoiding illumination for several days. Yield: 49%
(based on Ag). Anal. Calcd for C7H12N2O7SBrAg: C 18.44, H 2.65, N
6.14%; found C 18.48, H 2.70, N 6.10%. IR (ν/cm−1): 3423m, 3358s,
Figure 1. (a) Molecular structure of 1 with the ellipsoids drawn at the
50% probability level; the weak Ag−O interaction and hydrogen bonds
are denoted by dash line. (b) 1-D chain structure containing dinuclear
motifs. (c) 3-D supramolecular framework of 1.
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Inorganic Chemistry
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Anal. Calcd for C7H7O8SBrAg2: C 15.38, H 1.29%; found C 15.35, H
1.34%. IR (ν/cm−1): 3440s (br), 3070w, 1612m, 1563m, 1427s,
1365m, 1268m, 1203s, 1168s, 1029s, 896m, 846m, 796w, 700m, 615s,
538m.
1153s, 1132s, 1079s, 1010s, 943m, 881m, 773m, 711m, 634m, 565m,
545m.
Synthesis of [Ag3(L3)(NH3)3]n (7). A similar procedure with
complex 1 was carried out. The pH value was adjusted to ∼8 with
proper amount of ammonia, and pale-yellow crystals of 7 suitable for
X-ray diffraction were isolated from the filtrate after avoiding
illumination for several days. Yield: 44% (based on Ag). Anal. Calcd
for C7H12N3O6SAg3: C 14.25, H 2.05, N 7.12%; found C 14.28, H
2.01, N 7.15%. IR (ν/cm−1): 3334m, 3289m, 3220m, 3053w, 1583m,
1558m, 1477m, 1371s, 1311m, 1230w, 1176s, 1124m, 1066s, 1016s,
894w, 831w, 802w, 777m, 730m, 646s, 574w, 528m.
Synthesis of [Ag2(HL3)]n (8). A similar procedure with complex 3
was carried out by changing H3L1 into H3L3. Colorless crystals of 8
suitable for X-ray diffraction were isolated. Yield: 61% (based on Ag).
Anal. Calcd for C7H4O6SAg2: C 19.47, H 0.93%; found C 19.45, H
0.89%. IR (ν/cm−1): 3440m, 3058w, 1606m, 1558s, 1479m, 1372s,
1310m, 1243m, 1182s, 1130s, 1070s, 1022s, 898w, 810w, 782m, 743m,
651m, 541m.
Synthesis of [Ag6(L3)2(H2O)3]n (9). A similar procedure with
complex 8 was carried out by changing the ration of metal to ligand
into 2:1, and pale-yellow crystals of 9 suitable for X-ray diffraction
were isolated. Yield: 67% (based on Ag). Anal. Calcd for C14H12-
O15S2Ag6: C 14.86, H 1.07%; found C 14.83, H 1.09%. IR (ν/cm−1):
3342m (br), 3045w, 1597m, 1560s, 1481m, 1369s, 1311m, 1241m,
1178s, 1128s, 1068m, 1020m, 894w, 844w, 802m, 775m, 730m, 646s,
576w, 539m.
Synthesis of [Ag2(HL2)(NH3)2]·H2O (4). A similar procedure with
complex 1 was carried out by changing H3L1 into H3L2. Colorless
crystals of 4 were isolated from the filtrate after avoiding illumination
for several days. Yield: 62% (based on Ag). Anal. Calcd for
C7H12N2O7SAg2: C 17.37, H 2.50, N 5.79%; found C 17.34, H
2.45, N 5.82%. IR (ν/cm−1): 3434m, 3340s, 3264m, 3056w, 1616m,
1592m, 1562s, 1409s, 1276m, 1251s, 1218s, 1184s, 1132m, 1076m,
1018s, 956m, 887m, 848w, 806m, 769m, 711m, 646s, 538m.
Synthesis of [Ag(H2L2)(H2O)]n (5). A similar procedure with
complex 3 was carried out by changing H3L1 into H3L2, and the
mixture was stirred for 10 min. Colorless crystals of 5 were isolated
from the filtrate after avoiding illumination for several days. Yield: 69%
(based on Ag). Anal. Calcd for C7H7O7SAg: C 24.51, H 2.06; found C
24.48, H 2.10. IR (ν/cm−1): 3410m, 3246m, 3059w, 1688s, 1609m,
1587m, 1504m, 1416s, 1365m, 1313s, 1217s, 1119s, 1080s, 1011s, 941
m, 888m, 763m, 708s, 639m, 568m, 530m.
Synthesis of [Ag2(HL2)]n (6). A similar procedure with complex 5
was carried out by changing the ration of metal to ligand into 1.5:1,
and the mixture was stirred for 20 min. Colorless crystals of 6 suitable
for X-ray diffraction were isolated. Yield: 71% (based on Ag). Anal.
Calcd for C7H4O6SAg2: C 19.47, H 0.93; found C 19.51, H 0.88. IR
(ν/cm−1): 3440m, 3058w, 1606m, 1544s, 1413s, 1332s, 1253m, 1193s,
Figure 2. (a) Perspective view of the asymmetric unit of 2 showing the coordination environments around the silver centers with the ellipsoids
drawn at the 50% probability level. (b) 1-D double chain structure with the carbon atoms of S1-containing dianions denoted as lime sticks. (c) 2-D
layer structure extended by the Ag−Br interactions (blue bonds) linking adjacent chains. (d) 3-D Host−guest framework with the ammonium
cations encapsulated in the channels.
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Inorganic Chemistry
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X-ray Crystallographic Measurements. Table 1 provides a
summary of the crystal data, data collection, and refinement
parameters for the complexes 1−9. All diffraction data were collected
at 295 K on a RIGAKU RAXIS-RAPID diffractometer with graphite
monochromatized Mo Kα (λ = 0.71073 Å) radiation in ω scan mode.
All structures were solved by direct method and difference Fourier
syntheses. All non-hydrogen atoms were refined by full-matrix least-
squares techniques on F2 with anisotropic thermal parameters. The
hydrogen atoms attached to carbon atoms were placed in calculated
positions with C−H = 0.93 Å and U(H) = 1.2Ueq (C) in the riding
model approximation. The hydrogen atoms of hydroxyl groups in
complexes 1−6, 8 and water molecules in complexes 1−5, 9 were
placed in calculated positions and located in difference Fourier maps
and refined in the riding model approximation, with O−H distances
restraint (0.82 or 0.85(1) Å) and U(H) = 1.5Ueq (O), respectively.
Hydrogen atoms of ammonia molecules in complexes 1, 2, 4, and 7
were placed in calculated positions with N−H = 0.89 Å and U(H) =
1.5Ueq (N), while the hydrogen atoms of ammonium cations in
complexes 1 and 2 were located in difference Fourier maps and refined
in the riding model approximation, with N−H distances restraint
(0.86(1) or 0.89(1) Å) and U(H) = 1.5Ueq (N). All calculations were
carried out with the SHELXL97 program.13 The CCDC reference
numbers are 836149−836156 and 798868 for complexes 1−9.
Selected bond distances and angles and selected hydrogen bond
parameters for all complexes are presented in Table S1 and Table S2,
respectively (Supporting Information).
and Ag2 ions to generate tetranuclear motifs, which further
connect by S1-containing HL12‑ dianions in the same mode,
thus forming 1-D double chain structure along the diagonal of
ac plane. The short Ag1···Ag2 distance of 2.9033(9) Å indicates
the existence of argentophilic interaction.15 Subsequently, the
Br atoms of S1-containing HL12− dianions coordinate to the
Ag1 ions of adjacent chains and extend the chains into 2-D
layer structure with the Ag−Br bond of 2.9978(10) Å falling in
the reported range of 2.7−3.0 Å (Figure 2c).16 Finally, Ag3 ions
join the 2-D layers through the coordination of sulfonate
oxygen atoms (O2 and O9) and hydroxyl atoms (O4), thus
giving rise to 3-D host−guest framework with the ammonium
cations encapsulated in the channels (Figure 2d).
RESULTS AND DISCUSSION
■
Structure of (NH4)·[Ag(HL1)(NH3)(H2O)] (1). Single-
crystal X-ray diffraction analysis reveals that complex 1 presents
3-D supramolecular network extended by the N/O−H···O
hydrogen bonds. As illustrated in Figure 1a, the asymmetric
unit consists of one ammonium cation and 0-D discrete
structure of [Ag(HL1)(NH3)(H2O)]− anion. The coordination
sphere of Ag(I) ion can be best described as T-shaped
geometry with the long separation of 2.945(4) Å indicating the
existence of weak Ag(I)−O6 interaction.14 The sulfonate
groups in HL12‑ dianions do not coordinate to Ag(I) and
just direct toward water H atoms to form classic O−H···O
hydrogen bonds which link the mononuclear unit into
dinuclear motif. Adjacent dinuclear motifs are further
interconnected by the hydrogen bonds between coordinated
ammonia molecules and carboxylate groups to form a 1-D
chain structure, in which the π···π stacking interactions between
the opposite phenyl rings are observed with the centroid-
to-centroid distances of 3.627 Å (Figure 1b). Subsequently, the
ammonium cations bridge the aforementioned chains into 3-D
supramolecular network through N−H···O hydrogen bonds
(Figure 1c).
Structure of {(NH4)·[Ag3(HL1)2(NH3)(H2O)]}n (2). As
illustrated in Figure 2a, the asymmetric unit of complex 2
contains three crystallographically unique Ag(I) ions, two
HL12− dianions, one coordinated ammonia molecule, one
coordinated water molecule and one ammonium cation. Ag1
displays distorted trigonal bipyramid geometry while Ag2
exhibits T-shaped geometry. The coordination sphere of Ag3
can be described as twist quadrilateral geometry which is rarely
observed in silver(I)-complexes (Figure S2 in Supporting
Information). The O4 and O9iv atoms locate on top of the N1/
Ag3/O2 plane with the vertical distances being 0.556 and 0.859
Å. The two HL12− dianions adopt different coordination
modes and interlink adjacent Ag(I) ions to form the final 3-D
hybrid framework, which can be understood in the following
manners. First, as shown in Figure 2b, the S2-containing HL12−
dianions in the μ1 (sufonate): μ2 (carboxylate) mode join Ag1
Figure 3. (a) Perspective view of the asymmetric unit of 3 showing the
coordination environments around the silver centers with the
ellipsoids drawn at the 50% probability level. (b) Representation of
the 2-D layer (red polyhedra: Ag1; green polyhedra: Ag2; sky blue
bonds: Ag···Ag interactions). (c) Illustration of the 3-D network
formed by the hydrogen bonds linking adjacent layers.
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Structure of [Ag2(HL1)(H2O)2]n (3). The asymmetric unit
of complex 3 contains two crystallographically unique Ag(I) ions,
one HL12− dianion and two coordinated water molecules, in
which the two Ag(I) ions exhibit different coordinating geometries
(Figure 3a). Ag1 exhibits distorted square-pyramidal geometry,
while Ag2 can be best described as distorted tetrahedral geometry
with the long contact of 2.931(5) Å (Ag2−O2) being considerably
less than the sum of the van der Waals radii (3.24 Å). As shown in
Figure 3b, two Ag1 ions are bridged by two symmetry-related O1
atoms of sulfonate groups and form binuclear units, which are
further joined by the pairs of O3 atoms of sulfonate groups to
generate a 1-D tape along the a-axis. Ag2 ions are fastened by the
residual O2 atom of sulfonate group together with the carboxylate
oxygen atoms and arranged along the two edges of the 1-D tape,
which connect adjacent tapes into 2-D layer structure. Weak
Ag···Ag interactions are observed between Ag2 ions with the
separation of 3.0472(16) Å. Furthermore, the 3-D framework with
regular channels is formed by the extensive hydrogen bonds
involving the coordinated water molecules, sulfonate groups and
carboxylate groups (Figure 3c). The 1-D channels are occupied by
the coordinated HL12− dianions with the Br “tail” toward to the
sulfonate groups. The shortest distance between Br and O atoms
(3.066(6) Å) indicates the existence of weak Br···O interaction.
Structure of [Ag2(HL2)(NH3)2]·H2O (4). Single-crystal
X-ray diffraction analysis reveals that complex 4 is 0-D discrete
tetranuclear structure. The asymmetric unit contains two
crystallographically unique Ag(I) ions, one HL22‑ dianion, two
coordinated ammonia molecules and one free water molecule
(Figure 4a). Ag1 exhibits T-shaped geometry, while Ag2 exhibits
linear geometry. The two Ag(I) ions are bridged by the
carboxylate group in a bridging mode to generate a dinuclear
unit with the Ag···Ag separation of 2.9696(16) Å, which is
further linked by two symmetry-related HL22‑ dianions through
O1 atom into a tetranuclear motif. As shown in Figure 4b,
adjacent tetranuclear motifs are interconnected through pairs of
N(1)−H(1N1)···O(5) hydrogen bonds into 1-D chain
incorporating R22(8) rings along the c-axis. The Ag···Ag distance
of 3.4169(15) Å between the Ag2 ions in the ring indicates the
weak Ag···Ag interaction, owing to the distance being slightly
shorter than the summed van der Waals radii of two silver atoms
(3.44 Å).15 Subsequently, various N/O−H···O hydrogen bonds
between uncoordinated sulfonates, hydroxyl groups, coordi-
nated carboxylates and ammonia molecules link adjacent chains
into 3-D supramolecular network with the free water molecules
encapsulated in the hydrogen-bonding channels (Figure 4c).
Structure of [Ag(H2L2)(H2O)]n (5). Complex 5 shows 3-D
framework with the asymmetric unit composed of one Ag(I)
ion, one H2L2− monoanion and one coordinated water
molecule (Figure 5a). The coordination sphere of Ag(I) ion
Figure 4. (a) Perspective view of the asymmetric unit of 4 showing the
coordination environments around the silver center with the ellipsoids
drawn at the 50% probability level. (b) Illustration of the hydrogen-
bonding chain with the hydrogen bonds denoted by dash line. (c) 3-D
supramolecular network with the water molecules encapsulated in the
hydrogen-bonding channels.
Figure 5. (a) Perspective view of the asymmetric unit of 5 showing the
coordination environment around the silver center with the ellipsoids
drawn at the 50% probability level. (b) Ball-and-stick representation of
the Ag−O−S chain incorporating four-membered ring (pink) and
eight-membered ring (black). (c) Illustration of the 3-D hybrid
framework.
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Figure 6. (a) Perspective view of the asymmetric unit of 6 showing the coordination environments around the silver centers with the ellipsoids
drawn at the 50% probability level. (b) The Ag−O−S layer formed by the sulfonate groups linking silver chains (green balls, Ag1; sky blue balls,
Ag2). (c) Polyhedral representation of the Ag−O−S layer (red polyhedra, Ag1; green polyhedra, Ag2; blue polyhedra: sulfonate group).
(d) Illustration of the 3-D pillared layered structure.
can be described as distorted trigonal prism geometry with
the longer separation of 2.917(2) Å (Ag1−O4) capped the
lateral face. The sulfonate groups exhibit μ3 (κ2O1, κ1O2)
coordination mode and bridge adjacent Ag1 ions into 1-D chain
structure along the c-axis which incorporates four-membered
rings and eight-membered rings (Figure 5b). The Ag···Ag
distances of 3.6915(8) and 3.4867(6) Å in the two rings are
longer than the summed van der Waals radii of two silver atoms
(3.44 Å). Two hydroxyl groups cap each face of the eight-
membered ring in a μ2 mode. The carboxylate group acts in
monodentate mode and coordinates to the above 1-D chain,
thus leading to the formation of the 3-D hybrid framework
(Figure 5c).
Structure of [Ag2(HL2)]n (6). Figure 6a presents the
asymmetric unit of complex 6 which contains two crystallo-
graphically unique Ag(I) ions and one HL22− dianion. The
coordination sphere about Ag1 is distorted trigonal bipyramid
geometry, and even longer contacts to two adjacent Ag(I) ions
(Ag1···Ag2ii 3.0745(9) Å, Ag1···Ag1iii 3.3931(10) Å), while Ag2
has distorted tetrahedron geometry and connects to one Ag1
ion with the previously quoted distances and one Ag2 ion with
the distance of 2.9671(16) Å. It should be noted that adjacent
Ag(I) ions are connected into 1-D concave-convex chain along
the c-axis through the aforementioned Ag···Ag interactions. The
sulfonate group acts in μ4 (κ2O2, κ2O3) coordination mode
and bridges the concave-convex silver chains into 2-D layer
structure (Figure 6b). A pair of carboxylate O5 atoms caps each
face of the Ag4 core in an unusual μ3 mode. Instead, the 2-D
layer can be described as the edge-sharing Ag1 dimers modified
Ag2 polyhedral chain interlinked by the tetrahedron of the
sulfonate (CSO3) (Figure 6c). Figure 6d exhibits the 3-D
pillared layered framework of complex 6, in which the phenyl
rings act as the pillars. The interlayer distance, defined as the
perpendicular distance between planes of Ag(I) ions, is 9.23 Å,
and the thickness of a single lamella, defined as the region
containing solely the Ag, S, and O atoms, is 3.63 Å. Thus, the
gallery height present in complex 6 is 5.60 Å.
Structure of [Ag3(L3)(NH3)3]n (7). X-ray structural anal-
ysis reveals that the asymmetric unit comprises of a fully
deprotonated L33− trianion, three coordinated ammonia
molecules, two crystallographically unique Ag(I) ions and two
Ag(I) ions located in different inversion centers (Figure 7a).
Ag1 and Ag3 ions exhibit standard linear geometry, Ag2 ion is
almost linear geometry with N−Ag−O angle of 172.3(2)°. Ag4
ion exhibits T-shaped geometry. As observed in the
aforementioned complexes, the argentophilic interactions are
also found in complex 7 with the Ag···Ag distances of
3.0920(11) (Ag1···Ag2), 2.9918(15) (Ag4···Ag4iv), and
2.8094(8) Å (Ag3···Ag4), which make the present complex a
novel structure with unique features. As shown in Figure 7b, the
strong interactions between Ag3 and Ag4 extend the silver(I)
ions into 1-D silver chains, which are further bridged by
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μ3 mode of carboxylate O5 atom as observed in complex 6 to
generate interval eight-membered ring and three conterminous
four-membered rings. It should be noted that the argentophilic
interactions are found among the Ag(I) ions in the eight-
membered ring with a longer distance of 3.3419(13) Å (Ag1···
Ag2v) and a shorter distance of 2.7768(9) Å (Ag1···Ag1iv). The
assembly of these rings generates an infinite 1-D Ag−O tape
along the crystallographic a-axis (Figure 8b). From another
point of view, the 1-D tape can be described as dinuclears of
edge-sharing Ag2 polyhedra interlinked by discrete Ag1
polyhedra by sharing vertexes and edges. Subsequently, the
tetrahedrons of the sulfonates (CSO3) link adjacent 1-D Ag−O
tapes into 2-D infinite inorganic network substructure as
illustrated in Figure 8c. Figure 8d exhibits the 3-D pillared
layered framework of complex 8, in which the phenyl rings act
as the pillars. The gallery height of 4.78 Å (interlayer distance,
9.10 Å, the thickness of a single lamella, 4.32 Å) is shorter than
that of complex 6, which probably caused by the incline of the
phenyl rings to the single lamella and subsequently shorten the
distance between the adjacent layers.
Structure of [Ag6(L3)2(H2O)3]n (9). The molecular
structure of complex 9 is shown in Figure 9a, Ag1 and Ag2
ions exhibit T-shaped geometry, while Ag3 and Ag4 ions exist
in pseudotrigonal bipyramid geometry containing one carbon−
carbon π interaction from η2-benzene of the sulfonate. The
Ag−C distances for the two different ligands are unequal, being
2.404(8) and 2.559(8) Å for C6 and C7, 2.382(8) and 2.443(8)
Å for C13 and C14, respectively, which well lie in the limits
from 2.337 to 3.069 Å observed in the reported silver(I)−
aromatic complexes,17 and indicate the existence of the strong
Ag−C interactions. Ag5 ion has a tetrahedral geometry, while
Ag6 ion, occupying 50% of the silver sites, presents linear
geometry. The geometry of Ag7 ion can be described as
trigonal bipyramidal geometry. Interestingly, it should be noted
that ligand-supported argentophilic interactions can be
observed between adjacent Ag(I) ions with various Ag···Ag
separations: (i) Ag1···Ag1i (2.8511(18) Å); (ii) Ag1···Ag2
(3.3585(19) Å); (iii) Ag3···Ag4 (3.1339(10) Å); (iv) Ag5···Ag6
(2.8922(8) Å). These strong and weak Ag···Ag interactions15
lead to the coexistence of dinuclear unit of [Ag3Ag4], trinuclear
unit of [(Ag5)2Ag6] and tetranuclear unit of [Ag1Ag2]2. To the
best of our knowledge, such various motifs are not detected in
reported silver(I)−sulfonates.
Different from complexes 7 and 8, the fully deprotonated
L33‑ trianion in complex 9 exhibits two types of intricate and
novel coordination modes, namely, μ10-η5(SO3H): η3(OH):
η 3(COOH): η 2(CC) and μ 8-η 4(SO3H): η 3(OH):
η2(COOH): η2(CC) (Scheme 1). In contrast to the two
reported silver(I)-sulfonates involving a similar ligand
H3SSA,4e,f,5a the present coordination modes show unprece-
dented features. First, the μ3-bridging mode of the deproto-
nated hydroxyl group enriches the coordination fashion of L33−
group and coordination sphere of Ag(I) ion; Second, the strong
Ag−C interactions are observed in rarely reported silver(I)−
sulfonates;4c,7a Third, assistance of the hydroxyl group
intensifies the coordination ability of the so-called “weak”
−SO3 group and subsequently enriches the coordination
fashion of −SO3 group. As we reported in our previous
work,6a the O3 atom of the −SO3 (S1) group exhibits rare κ3
coordination mode,4c whereas Shimizu has stated that the
oxygen atoms of a −SO3 group will bridge a maximum to two
metal ions more typically.10b
Figure 7. (a) Perspective view of the asymmetric unit of 7 showing the
coordination environments around the silver centers with the
ellipsoids drawn at the 50% probability level. (b) The Ag−O−S
layer formed by the L3− trianions linking silver chains. (c) 3-D hybrid
framework formed by the interlinked short triatom sticks and silver
chains.
monodentate sulfonate group and bridging carboxylate group
to construct 2-D layer. By contrast, adjacent Ag1 and Ag2 ions
are linked by weak Ag···Ag interactions into short triatom
sticks. Subsequently, adjacent layers are linked by the short
triatom sticks through hydroxyl groups of L33− trianions to
afford the 3-D hybrid framework as illustrated in Figure 7c.
Structure of [Ag2(HL3)]n (8). Complex 8 is 3D pillared
layered framework with the asymmetric unit composed of two
crystallographically unique Ag(I) ions and one HL32− dianion
(Figure 8a). Ag1 locates in a tetrahedron sphere, while Ag2
displays trigonal bipyramid geometry. Adjacent Ag(I) ions are
bridged by the μ2 mode of sulfonate O1 atom and unusual
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Figure 8. (a) Perspective view of the asymmetric unit of 8 showing the coordination environments around the silver centers with the ellipsoids
drawn at the 50% probability level. (b) Infinite 1-D Ag−O tape with the Ag···Ag interactions denoted by sky blue solid line. (c) Polyhedral
representation of the Ag−O−S layer (red polyhedra, Ag1; green polyhedra, Ag2; blue polyhedra, sulfonate group). (d) Illustration of the 3-D pillared
layered structure.
From the above statement, the most remarkable feature of
complex 9 is the four kinds of coordination spheres with low
coordination number of two to five. As shown in Figure 9b,
twelve polyhedra of Ag1, Ag2, Ag3, Ag4, Ag5, and Ag7
interconnected with each other by sharing vertexes and edges
to form a dodecanuclear subunit, which are further linked to
adjacent dodecanuclear subunits and Ag6 linear sticks through
strongly argentophilic interactions between two adjacent Ag1
ions and Ag5, Ag6 ions to generate the inorganic lamellar
network extending in the ab plane. Moreover, the pillars of
L33− groups bridge the adjacent layers to afford the 3-D pillared
layered framework (Figure 9c). The difference of 6.26 Å
between the interlayer distance (9.61 Å) and the thickness of a
single lamella (3.35 Å) constitutes the gallery height, which
is obviously shorter than that of [Ag4(HSSA)2(H2O)2]n
(16.24 Å).4e,f,5a The remarkable decrease of galley height may
be attribute to the distinct coordination modes of the ligands.
Furthermore, in our previous work, we presented the first
silver-MPF of [Ag5(4-pyridone-3-sulfonate)3(NO3)2(H2O)]n
(HLJU-1) which contains continuous silver(I) polyhedra with
the higher coordination numbers of five to eight.6a By contrast,
complex 9 represents another silver(I)−MPF containing four
kinds of coordination spheres with low coordination number of
two to five. This result also indicates that all the coordination
spheres of Ag(I) ion with coordination numbers two to eight
could afford the formation of silver(I)−MPFs.
Influencing Factor of the Structural Evolutions. It can
be concluded from the aforementioned structural descriptions
that the overall topological structures and the coordination
spheres of Ag(I) ions of complexes 1−9 present intriguing
variations (Figure S2 in Supporting Information). The
structural evolutions are influenced by the synthetic methods,
coordination modes and different benzenesulfonic acid ligands
decorated by hydroxyl and carboxyl groups.
As illustrated in Chart 1, during the synthetic process with
AgNO3 and three benzenesulfonic ligands, two 0-D structures
of 1, 4 and two 3-D frameworks of 2, 7 were obtained by
adjusting the pH value to ∼6 and 7−8 with proper amount of
ammonia, respectively. In most cases, 0-D structures are more
easier to be form in the above system owing to the strong
affinity of ammonia to Ag(I) ion. However, the increasing of
pH value and the formation of the additional Ag−Br and
Ag···Ag interactions in complexes 2 and 7 afford two 3-D
frameworks. Changed the metal salt into Ag2CO3, one 2-D
layer of 3 and four 3-D networks of 5, 6, 8, and 9 with the
corresponding benzenesulfonic ligands were obtained. In other
words, the avoidance of ammonia could supply more
coordinating space for the weak sulfonates to Ag(I) centers,
thus effectively modulating the topological architectures and
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complexes with the assistant of carboxyl groups. In complexes
1 and 4, the sulfonate groups exhibit uncoordinated and simple
monodentate modes, while the carboxyl groups exhibit
monodentate and bridging modes, respectively. Accordingly,
such simple coordination modes and the terminal coordination
of ammonia lead to the formation of two 0-D complexes. The
sulfonate groups in complexes 2 and 3 exhibit μ2 (κ1O: κ1O)
and μ4 (κ2O: κ1O: κ1O) modes, whereas the carboxyl groups
exhibit the same bridging mode. However, complex 2 presents
3-D framework with the connection of Ag−Br bonds in
contrast to complex 3. The monodentate mode of hydroxyl
groups in complexes 6 and 8 makes the sulfonate groups exhibit
the same μ4 (κ2O: κ2O) fashions, which connect adjacent
Ag(I) ions to give rise to 1-D concave−convex chain (complex
6) and 1-D tape (complex 8). The carboxyl groups, with rarely
μ4 (κ1O: κ3O) mode, link the aforementioned chains into 3-D
pillared layered frameworks. Different from the above six
complexes, the hydroxyl group in complex 5 exhibits μ2-
bridging mode and connects adjacent Ag(I) ions with μ3-
bridging (κ2O: κ1O) sulfonate group and monodentate
carboxyl group to generate 3-D framework. Although the
hydroxyl group in complex 7 is deprotonated, the sulfonate
group only exhibits the simplest monodentate mode.
Fortunately, the bridging carboxyl group and the Ag···Ag
interactions extend complex 7 into 3-D frameworks. By
contrast, the deprotonated hydroxyl group in complex 9 exhibit
interesting μ3-bridging mode as reported in previous work.6
Simultaneously, the sulfonate groups act in μ4 (κ2O: κ2O) and
μ4 (κ2O: κ1O: κ1O) modes, while the carboxyl groups act in
bridging and μ 3 (κ 2O: κ 1O) modes. These intricate
coordination modes of the three functional groups result in
the formation of 3-D pillared layered frameworks.
On the basis of the above description, the hydroxyl and
carboxyl group-substitued benzenesulfonic acids are excellent
bridging ligands, which can be used to construct 3-D
frameworks. Moreover, the acquirement of complex 9 further
demonstrate the conclusion that deprotonated hydroxyl group
can form novel μ3-bridging mode and result in complicated
coordination modes of sulfonate group, which, in turn, create
the large tendency to form high dimensional frameworks.
Importantly, the carboxyl groups in the nine complexes present
four types of coordination modes, namely, μ1 (κ1O), μ2 (κ1O:
κ1O), μ3 (κ2O: κ1O), and μ4 (κ1O: κ3O), which indicates that
the carboxyl group possesses strong coordination ability in
comparison with the hydroxyl and sulfonate groups. The μ2 to
μ4 mode play crucial role in the construction of high-
dimensional networks. Especially, the μ4 (κ1O: κ3O) fashion
in complexes 6 and 8 is rarely observed in the reported
silver(I)−carboxylates.12
Figure 9. (a) Perspective view of the asymmetric unit of 9 showing the
coordination environments around the silver centers with the
ellipsoids drawn at the 50% probability level; the Ag···Ag interactions
denoted by sky blue solid line. (b) Perspective view of the inorganic
lamellar network, showing the different polyhedra of Ag(I) ions
(orange stick denoted the linear coordination geometry of Ag6).
(c) Illustration of the 3-D hybrid framework.
leading to high-dimensional structures. The formation of these
complexes clearly demonstrates that the strong affinity of
ammonia molecules and the N-heterocyclic ligands to Ag(I)
ions is more preferable to afford the formation of linear unit
−N−Ag−N−, which consequently prevents the coordination of
sulfonates and induces the formation of low-dimensional
structures.
In a more elaborate analysis, the form (deprotonated or not)
and coordination behavior of the ortho-hydroxyl groups directly
affect the coordination modes of the sulfonate groups, which
subsequently generate different networks together with the
multiple coordinating carboxyl groups. The hydroxyl group,
when remains the H atom, exhibits three states, namely,
uncoordinated (complexes 1, 2, and 4), monodentate
(complexes 2, 3, 6, and 8) and μ2-bridging (complex 5)
modes. Whereas the deprotonated hydroxyl group exhibits
common monodentate (complex 7) and rare μ3-bridging
mode (complex 9) as observed in our previous work.6 With the
change of hydroxyl group, the sulfonate group exhibits diverse
coordination modes, which determines the dimension of the
IR Spectroscopy. The peaks observed at the range of
1617−1583 cm−1 for complexes 1−4 and 6−9 are assigned to
the stretching bands of νas(COO−), while the peaks observed
at the range of 1427−1369 cm−1 can be assigned to the
stretching bands of νs(COO−). The observations of these
peaks indicate that the carboxyl groups in complexes 1−4 and
6−9 are deprotonated and coordinate to the Ag(I) ion in
diverse coordination modes.18 By contrast, the peak at 1688
cm−1 for complex 5 can be attributed to the vibration of CO,
which demonstrates that the H atom of the carboxyl group is
−
not removed. The characteristic vibrations of νas(SO3 ) in
complexes 1−9 are at the range of 1268−1119 cm−1, whereas
the νs(SO3 ) absorptions are at the range of 1037−1010 cm−1.
−
In addition, the IR spectra of complexes 1−9 exhibit strong and
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Scheme 1. Coordination Modes of the Three Arenesulfonate Ligands in Complexes 1−9
broad absorptions in the range of 3480−3178 cm−1, occurring
because of the existence of hydrogen bonds formed by water
molecules, ammonia molecules, ammonium cations, as well as
the hydroxyl groups in the nine complexes.
Chart 1. Representation of the Synthetic Process of
Complexes 1−9
Luminescent Property. Complexes with d10 metal centers
and organic ligands are promising candidates for photo-
luminescent materials.19 The luminescent properties of
complexes 1−9 and three free ligands in the solid-state at
room temperature were investigated. Upon excitation at 328,
280, and 313 nm, free ligands H3L1−H3L3 exhibit emission
maximum at 456, 353, and 437 nm, which is probably attribute
to the intraligand transitions (Figure 10 and Figure S3 in
Supporting Information). Unfortunately, no obvious emissions
for complexes 4 and 6−9 were detected. As shown in Figure
10a and Figure 10b, upon excitation at 339 nm, complexes 1−3
exhibit blue emission maximum at 442, 434, and 438 nm, while
complex 5 exhibits purple blue emission maximum at 369 nm
upon excitation at 328 nm (for Luminescent photographs of
the four complexes, see Figure S4 in Supporting Information).
These fluorescent emission bands can probably be assigned to
the intraligand (IL) π−π* transitions because the resemblance
of the emission spectra in comparison with free ligands H3L1
and H3L2.7b,20 The blue shifts of the emission peaks in
complexes 1−3 and red shift of the emission peak in complex 5
are probably attributable to the differences of ligands and the
coordination environment around Ag(I) ions.21
Owing to the strong emission and well solubility in aqueous
solution, complex 1 was selected to investigate its luminescent
behavior. An attractive luminescent feature of complex 1 is the
sensitization to lanthanide. Usually, Eu(III) and Tb(III) ions
cannot exhibit characteristic emission at room temperature in
aqueous solution. However, it is interesting to note that the
addition of the same equivalent of complex 1 into the aqueous
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solution, the energy gap between the ligand triplet state and the
emitting level of the Tb(III) ion may be in favor of the energy
transfer process. Whereas the energy gap between the ligand
triplet state and the emitting level of the Eu(III) ion was not in
favor of the energy transfer process and thus no obvious
characteristic emissions of Eu(III) ion was observed. Although
the mechanism for sensitization to Tb(III) ion is still not clear
at this moment, the replacement of Ag(I) ion by Tb(III) ion
and the coordination of the free functional groups to the
Tb(III) ion definitely play an important role. Moreover, the
luminescent properties of complex 1 in different solvents and
different pH values in aqueous solution were also investigated
due to the solubility in different solvents. (Figure S5 and S6 in
Supporting Information).
CONCLUSIONS
■
In summary, self-assembly of silver(I) salts and three
benzenesulfonic acids decorated by hydroxyl and carboxyl
groups leads to the formation of a new family of silver(I)-
sulfonates with two 0-D discrete motifs, one 2-D layer, and six
3-D frameworks. The structural diversities and evolutions can
be attributed to the synthetic methods, different ligands and
coordination modes of the three functional groups. Lumines-
cent investigations indicate that complexes 1−3 and 5 exhibit
strong blue emissions at room temperature. Moreover, it is
interesting to note that complex 1 can sensitize Tb(III) ion to
exhibit characteristic emissions at room temperature in aqueous
solution.
This study clearly demonstrates that the attachment of
carboxyl and hydroxyl groups to the benzenesulfonic acid can
effectively bridge more metal centers to construct 3-D
frameworks. This result must promote the development of
crystal engineering and coordination chemistry of metal-
sulfonates. Bear these results in mind, further syntheses,
structures and properties studies of high-dimensional silver(I)−
sulfonates with multiple functional arenesulfonic acids are also
underway in our laboratory.
Figure 10. (a) Emission spectra of complexes 1−3 and ligand H3L1 in
the solid-state at room temperature. (b) Emission spectrum of
complex 5 and ligand H3L2 in the solid-state at room temperature.
solution makes the Tb(III) ion exhibit the characteristic
5
7
transition of D4 → FJ (J = 3−6) (Figure 11). But in the
ASSOCIATED CONTENT
* Supporting Information
■
S
Additional figures, luminescent behavior of complex 1, TG
analyses, selected bond distances and angles, and selected
hydrogen bond parameters for all complexes, as well as the
X-ray crystallographic files in CIF format. This material is
available free of charge via the Internet at http://pubs.acs.org.
ACKNOWLEDGMENTS
■
This work is financial supported by the Key Project of Natural
Science Foundation of Heilongjiang Province (No.
ZD200903), Key Project of Education Bureau of Heilongjiang
Province (No. 12511z023, No. 2011CJHB006), and the
Innovation team of Education bureau of Heilongjiang Province
(No. 2010td03). We thank the University of Heilongjiang
(Hdtd2010-04, yjscx2010-015hlju) for supporting this study.
Special thanks are offered to Xin-Lei Li, a student of Fuzhou
No. 19 Middle School in Fujian China, for the drawing of the
two cartoons in the TOC picture.
Figure 11. Emission spectra of complex 1 upon addition of 1 × 10−4
mol·L−1 of Tb(NO3)3 in aqueous solution. Inset: Photographs of
complex 1 in aqueous solution and after addition of 1 × 10−4 mol·L−1
of Tb(NO3)3.
aqueous solution containing equal amount of Eu(III) ion and
complex 1, the luminescence characteristic emission wave-
lengths of the Eu(III) ion were not observed. It is well-known
that the luminescence of Ln(III) is related to the efficiency of
the energy transfer from the triplet state of the ligand to the
emitting level of the Ln(III) ions, which depends on the energy
gap between the two levels.22 In Tb(III) ion containing
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