Novel eclipsed 2D cadmium(II) coordination polymers with open-channel structure constructed from terephthalate and 3-(2-pyridyl)pyrazole: Crystal structures, emission properties, and inclusion of guest molecules

Article abstract of DOI:10.1021/ic049625e

Five new eclipsed two-dimensional (2D) coordination polymers, {[Cd ₂(TPT)₂L₂](GM¹)₃/ ₂(H₂O)}∞ (1) (TPT = terephthalate, L = 3-(2-pyridyl)pyrazole, GM¹ = terephthalic a

Full text of DOI:10.1021/ic049625e

Inorg. Chem. 2004, 43, 5382−5386
Novel Eclipsed 2D Cadmium(II) Coordination Polymers with
Open-Channel Structure Constructed from Terephthalate and
3-(2-Pyridyl)pyrazole: Crystal Structures, Emission Properties, and
Inclusion of Guest Molecules
Ru-Qiang Zou, Xian-He Bu,* and Ruo-Hua Zhang
Department of Chemistry, Nankai UniVersity, Tianjin 300071, P. R. China
Received March 20, 2004
1
Five new eclipsed two-dimensional (2D) coordination polymers, {[Cd2(TPT)2L2](GM )3/2(H O)}∞ (1) (TPT )
2
1
2
2
terephthalate, L ) 3-(2-pyridyl)pyrazole, GM ) terephthalic acid), {[Cd(TPT)L](GM )(H O)2}∞ (2) (GM ) L )
2
3
3
4
4
3-(2-pyridyl)pyrazole), {[Cd(TPT)L](GM )1/2(H O)}∞ (3) (GM ) mesitylene), {[Cd4(TPT)4L4](GM )7/2}∞ (4) (GM )
2
5
5
tetramethylbenzene), and {[Cd(TPT)L](GM )1/2}∞ (5) (GM ) naphthalene), have been synthesized and characterized
by X-ray diffraction. All the five complexes take the similar eclipsed 2D open-channel framework with different
guest molecules included in the cavities of their channels. TGA analysis indicates that the eclipsed open-channel
frameworks are thermally stable up to 300 °C. The porous property of the 2D framework of 5 was also investigated
by the XRPD technique, which indicated that the guest molecules included in the open-channel frameworks are
removable and the framework is maintained after the removal of the guest molecules. Moreover, complexes 1−5
also display strong blue emission in the solid state.
Introduction
polymers have been built with homoleptic ligands. There are
also a few interesting examples that have been reported,
including some bridging ligand combinations;12 however, the
development of systems containing both chelating and
The design of coordination networks with porous structures
or open frameworks including removable solvents or ex-
changeable ions that provide new sizes, shapes, and chemical
environments has been of great interest in recent years, due
to their potential for many applications,1,2 for example,
mimicking zeolites. In this regard, various carboxylate
ligands have been used to design such moderately robust
frameworks,3-6 among which terephthalato, exhibiting a
variety of bridging modes and strong tendency to form large,
tightly bound metal cluster aggregates, has been used as
building block to construct porous coordination frame-
works.7-11 On the other hand, so far most of the coordination
(2) For examples: (a) Liu, Y. H.; Liu, Y. L.; Wu, H. C.; Wang, J. C.;
Lu, K. L. Inorg. Chem. 2002, 413, 2592. (b) Kuznicki, S. M.; Bell,
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Chem. Soc. 1998, 120, 2186 and references therein.
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8, 2743.
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(10) Cano, J.; DeMunno, G.; Sanz, J. L.; Faus, J.; Lloret, F.; Julve, M.;
Caneschi, A. J. Chem. Soc., Dalton Trans. 1997, 1915.
(11) (a) Burger, K. S.; Chaudhuri, P.; Weighardt, K.; Nuber, B. Chem.s
Eur. J. 1995, 1, 583. (b) Chaudhuri, P.; Oder, K.; Weighardt, K.;
Gehring, S.; Hasse, W.; Nuber, B.; Weiss, J. J. Am. Chem. Soc. 1988,
110, 3657.
* Author to whom correspondence should be addressed. E-mail: buxh@
nankai.edu.cn. Tel.: +86-22-23502809. Fax: +86-22-23502458.
(1) For examples: (a) Chae, H. K.; Siberio-Perez, D. Y.; Kim, J.; Go,
Y.; Eddaoudi, M.; Matzger, A. J.; O’Keeffe, M.; Yaghi, O. M. Nature
2004, 427, 523. (b) Kim, Y.; Suh, M.; Jung, D. Y. Inorg. Chem. 2004,
43, 245. (c) Huang, Z.; Song, H.-B.; Du, M.; Chen, S.-T.; Bu, X.-H.;
Ribas, J. Inorg. Chem. 2004, 43, 931. (d) Carvalho, A. P.; Castanheira,
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5382 Inorganic Chemistry, Vol. 43, No. 17, 2004
10.1021/ic049625e CCC: $27.50 © 2004 American Chemical Society
Published on Web 07/30/2004

Eclipsed 2D Cadmium(II) Coordination Polymers
{[Cd(TPT)L](GM2)(H2O)2}∞ (2) (GM2 ) L ) 3-(2-Pyridyl)-
pyrazole). The colorless crystals of complex 2 were obtained by
the reaction of Cd(NO3)2‚6H2O, terephthalic acid, 3-(2-pyridyl)-
pyrazole (L), and NaOH in the molar ratio of 1:1:2:4 using a pro-
cedure similar to that of 1. Yield: ∼55%. Anal. Calcd for C24H22-
CdN6O6: C, 47.81; H, 3.68; N, 13.94. Found: C, 47.46; H, 3.53;
N, 13.67. IR (KBr, cm-1): 3412 m, 3104 m, 3064 m, 2964 m,
2823 m, 1972 w, 1682 vs, 1574 s, 1287 s, 1113 m, 1019 m, 781 s,
560 w. TGA data (peak positions): 172, 380, 415, and 462 °C.
{[Cd(TPT)L](GM3)1/2(H2O)}∞ (3) (GM3 ) Mesitylene),
bridging ligands is still less explored. Considering most of
the reported complexes containing the terephthalate (TPT)
ligands and CdII ions are apt to form 3D networks when
geometry permits and the seventh coordinated ligand is labile,
which is very similar to the case of [Cu3(TMA)2(H2O)3]n
(TMA ) 1,3,5-benzenetricarboxylic acid) and [Cd(py)(TPT)]n
(py ) pyridine) in which the lability of the aqua ligands
allows their replacement by other groups,13 we attempted to
use some chelating bidentate ligands, such as 3-(2-pyridyl)-
pyrazole (L), to occupy two coordination sites of CdII to
design novel 2D networks. We have successfully obtained
five new eclipsed 2D coordination polymers, {[Cd2(TPT)2L2]-
(GM1)3/2(H2O)}∞ (1) (L ) 3-(2-pyridyl)pyrazole, GM1 )
terephthalic acid), {[Cd(TPT)L](GM2)(H2O)2}∞ (2) (GM2 )
L ) 3-(2-pyridyl)pyrazole), {[Cd(TPT)L](GM3)1/2(H2O)}∞
(3) (GM3 ) mesitylene), {[Cd4(TPT)4L4](GM4)7/2}∞ (4) (GM4
) tetramethylbenzene), and {[Cd(TPT)L](GM5)1/2}∞ (5)
(GM5 ) naphthalene), with different guest molecules ac-
commodated in their open-channel structures. Moreover, such
complexes display strong blue emission in the solid state.
Herein, we report the synthesis, structure, and emission prop-
erties of 1-5, which represent typical controllable examples
of metal coordination polymers with open-channel structures.
{[Cd4(TPT)4L4](GM4)7/2
}
(4) (GM4 ) Tetramethylbenzene),
∞
and {[Cd(TPT)L](GM5)1/2
}
∞
(5) (GM5 ) Naphthalene). These
three complexes were synthesized by the reactions of Cd(NO3)2‚
6H2O, terephthalic acid, 3-(2-pyridyl)pyrazole, NaOH, and corre-
sponding guest molecules in the molar ratio of 1:1:1:2:4 using a
synthetic method similar to that of 1 and 2.
Complex 3. Yield: ∼50%. Anal. Calcd for C20.25H18.25CdN3O5:
C, 49.03; H, 3.71; N, 8.47. Found: C, C, 39.41; H, 3.56; N, 8.69.
IR (KBr, cm-1): 3401 m, 3121 m, 2832 m, 2543 m, 1681 vs, 1543
s, 1385 s, 1133 m, 1108 w, 813 s, 685 m. TGA data (peak
positions): 173, 282, 339, 398, and 435 °C.
Complex 4. Yield: ∼40%. Anal. Calcd for C99H93Cd4N12O16:
C, 55.14; H, 4.35; N, 7.79. Found: C, 54.79; H, 4.47; N, 7.98. IR
(KBr, cm-1): 3105 m, 3061 m, 2832 m, 1972 w, 1688 vs, 1423
vs, 1285 s, 1133 m, 1008 m, 791 s, 525 m. TGA data (peak
positions): 187, 305, 340, and 422 °C.
Experimental Section
Complex 5. Yield: ∼40%. Anal. Calcd for C21H15CdN3O4: C,
51.92; H, 3.11; N, 8.65. Found: C, 51.56; H, 3.01; N, 9.01. IR
(KBr, cm-1): 3423 w, 3117 w, 3045 w, 2914 w, 1712 w, 1605 m,
1563 vs, 1505 s, 1432 s, 1386 vs, 1290 m, 1094 w, 840 m, 746 s,
520 m. TGA data (peak positions): 201, 317, 337, and 439 °C.
X-ray Data Collection and Structure Determinations. X-ray
single-crystal diffraction data for complexes 1-5 were collected
on a Bruker Smart 1000 CCD diffractometer at 293(2) K with Mo
KR radiation (λ ) 0.710 73 Å) by the ω scan mode. The program
SAINT15 was used for integration of the diffraction profiles. All
the structures were solved by direct methods using the SHELXS
program of the SHELXTL package and refined by full-matrix least-
squares methods with SHELXL (semiempirical absorption correc-
tions were applied using the SADABS program).16 Metal atoms in
each complex were located from the E-maps, and other non-
hydrogen atoms were located in successive difference Fourier
syntheses and refined with anisotropic thermal parameters on F2.
The hydrogen atoms of ligands were generated theoretically onto
the specific atoms and refined isotropically with fixed thermal
factors (the hydrogen atoms of water molecules were located using
the difference Fourier method). Further details for structural analysis
are summarized in Table 1.
Materials and General Methods. All the solvents and reagents
for synthesis, including terephthalic acid, were commercially
available and used as received. 3-(2-Pyridyl)pyrazole (L) was
synthesized by the literature method.14 FT-IR spectra (KBr pellets)
were taken on a 170SX (Nicolet) spectrometer. Elemental analyses
were performed on a Perkin-Elmer 240C analyzer. Thermogravi-
metric analysis (TGA) was carried out on a Dupont thermal analyzer
from room temperature to 600 °C under nitrogen atmosphere. X-ray
powder diffraction (XRPD) studies were recorded on a Rigaku
RU200 diffractometer at 60 kV and 300 mA for Cu KR radiation
(λ ) 1.5406 Å). Emission spectra were taken on a Stetlofluorometer
FL111AI spectrometer.
Synthesis of {[Cd2(TPT)2L2](GM1)3/2(H2O)}∞ (1) (TPT )
Terephthalate, L ) 3-(2-Pyridyl)pyrazole, GM1 ) Terephthalic
Acid). Complex 1 was obtained by the reaction of Cd(NO3)2‚6H2O,
terephthalic acid, 3-(2-pyridyl)pyrazole (L), and NaOH in the molar
ratio of 1:2:1:4 mixed with 12 mL of water under hydrothermal
conditions at 120 °C for 2 days. The colorless crystals were washed
by water and acetone and dried in air. Yield: ∼50%. Anal. Calcd
for C44H33Cd2N6O15: C, 47.59; H, 2.99; N, 7.57. Found: C, 47.91;
H, 3.13; N, 7.84. IR (KBr, cm-1): 3335 m, 3161 w, 2666 m, 1648
vs, 1607 m, 1463 s, 1291 s, 1023 m, 1003 m, 743 s, 696 w. TGA
data (peak positions): 163, 329, 401, and 459 °C.
Results and Discussion
Description of Structures. Complex 1. The structure of
1 consists of a 2D neutral coordination network {[Cd2-
(TPT)2L2](GM1)3/2(H2O)}∞ with terephthalic acid and lattice
water molecules included in the open-channel framework
(Figure 1). The local coordination environment around CdII
ion in 1 is the chelating L and chelating/bridging carboxylates
(Figure 1a). The b axial direction of 1 is occupied by the
chelating bidentate L ligands, and each terephthalato (TPT)
(12) (a) Tong, M.-L.; Chen, X.-M.; Yu, X.-L.; Mak, T. C. W. J. Chem.
Soc., Dalton Trans. 1998, 5. (b) Kitagawa, S.; Okubo, T.; Kawata,
S.; Kondo, M.; Katada, M.; Kobayashi, H. Inorg. Chem. 1995, 34,
4790. (c) Lu, J. Y.; Lawandy, M. A.; Li, J.; Yuen, T.; Lin, C. L. Inorg.
Chem. 1999, 38, 2695. (d) Zheng, L. M.; Fang, X.; Li, K. H.; Song,
H. H.; Xin, X. Q.; Fun, H. K.; Chinnakali, K.; Razak, I. A. J. Chem.
Soc., Dalton Trans. 1999, 2311. (e) MacGillicray, L. R.; Groeneman,
R. H.; Attwod, J. L. J. Am. Chem. Soc. 1998, 120, 2676. (f) Lightfoot,
P.; Snedden, A. J. Chem. Soc., Dalton Trans. 1999, 3549.
(13) (a) Chui, S. S. Y.; Lo, S. M. F.; Charmant, J. P. H.; Orpen, A. G.;
Williams, I. D. Science 1999, 283, 1148. (b) Fun, H. K.; Raj, S. S. S.;
Xiong, R.-G.; Zuo, J. L.; Yu, Z.; You, X. Z. J. Chem. Soc., Dalton
Trans. 1999, 1915.
(15) SAINT Software Reference Manual; Bruker AXS: Madison, WI, 1998.
(16) Sheldrick, G. M. SHELXTL NT Version 5.1. Program for Solution
and Refinement of Crystal Structures; University of Go¨ttingen:
Go¨ttingen, Germany, 1997.
(14) (a) Amoroso, A. J.; Cargill Thompson, M. W.; Jeffery, J. C.; Jones,
P. L.; McCleverty, J. A.; Ward, M. D. J. Chem. Soc., Chem. Commun.
1994, 2751. (b) Brunner, H.; Scheck, T. Chem. Ber. 1992, 125, 701.
Inorganic Chemistry, Vol. 43, No. 17, 2004 5383

Zou et al.
Table 1. Crystallographic Data and Structural Refinement Summary for Complexes 1-5
1
2
3
4
5
chem formula
fw
space group
a/Å
b/Å
c/Å
C44H33Cd2N6O15
1110.56
P1h
C24H22CdN6O6
602.88
P1h
C
20.25H18.25CdN3O5
C99H93Cd4N12O16
2156.45
P1h
10.347(5)
20.500(9)
23.426(10)
102.858(7)
95.683(7)
103.896(7)
4641(4)
293(2)
1.543
2
0.977
0.0460/0.0736
C21H15CdN3O4
485.76
P1h
482.52
P1h
10.347(4)
10.390(4)
21.833(8)
77.937(5)
88.261(5)
72.257(5)
2184.8(13)
293(2)
1.695
2
1.053
0.0278/0.0612
10.329(4)
10.354(4)
12.222(5)
113.765(6)
92.672(7)
108.919(6)
1107.7(8)
293(2)
1.808
2
1.044
0.0712/0.1949
10.325(3)
10.372(3)
12.344(3)
67.148(4)
72.038(4)
74.932(5)
1143.9(5)
293(2)
10.352(3)
10.373(4)
12.158(4)
94.659(5)
114.699(5)
105.995(5)
1111.0(7)
293(2)
1.452
2
1.012
0.0428/0.1055
R/deg
â/deg
γ/deg
V/Å3
T /K
Dc/g cm-3
Z
1.401
2
0.983
0.0520/0.1038
µ(Mo KR)/mm-1
Ra/wRb
2
2
2
a R ) Σ(||Fo| - |Fc||)/Σ|Fo|. b wR ) [Σ(|Fo| - |Fc| )2/Σ(Fo )]1/2
.
adopts a µ6-bridging mode to connect four CdII ions to extend
along the ac directions to form an eclipsed 2D network
structure (Figure 1b). The seven-coordinated geometry of
CdII is as follows: Two oxygen atoms of the two distinct
TPT carboxylate anions coordinate to CdII almost equally
in a bidentate chelating mode. The Cd-O distances (2.364-
2.518 Å) are quite similar to normal Cd-OCO distances
(2.251-2.879 Å).17 Second, the bridging Cd-O distances
(2.359(2) Å) are shorter than the chelating ones. Third, the
Cd-N distances (2.311(2) and 2.377(2) Å, respectively) are
also falling into the normal range (2.32-2.39 Å).18 The TPT
anion acts as bis-tridentate ligand to bridge the two coplanar
CdII ions and other two CdII ions in the same layer, resulting
in the formation of a 2D network with channel dimensions
of 10.43 × 10.43 Å2 passing the eclipsed 2D layers. It can
be seen from a perspective view of 1 down the b axis that
the green layer (see Figure 1b) is completely covered by the
red one, indicating that the adjacent 2D layers are eclipsed
each other. When viewed from the c axis (Figure 1c), the
separation between the adjacent L ligands located in the
adjacent 2D layers is about 3.638 Å, indicating the existence
of weak π-π stacking interactions.19 Water molecules and
terephthalic acid molecules were included in the channel
(Figure 1d).
water molecules and guest (3-(2-pyridyl)pyrazole) (L) in-
cluded in the channel (Figure 2a). The 2D eclipsed frame-
work and the local coordination environment around CdII in
2 are similar to that of 1, but different guest molecules are
included in their framework channels. The channels contain
diffuse electron density, which is difficult to model as
discrete atoms. Application of a continuous solvent-area
model led to satisfactory refinement, suggesting a contribu-
tion of ca. 193 electrons/unit cell from the channel region.
This is consistent with ca. two included L and four lattice
water molecules per unit cell, which is consistent with the
result of elemental analysis.
Complexes 3-5. The frameworks of 3-5 are similar to
that of 1 and 2, but different guest molecules are included
in their open-channel frameworks (see Figure 2b-d). The
diffuse electron density included in the open-channel frame-
works has been calculated to lead to satisfactory results
(Table 2), which are also consistent with the result of
elemental analysis.
Exclusion of Guest Molecules of 5: TGA and XRPD
Studies. As described above, all five complexes have the
2D eclipsed frameworks exhibiting open channels filled with
guest molecules. To verify whether the framework will be
maintained after the removal of the guest molecules, which
is important for new microporous materials, TGA and XRPD
techniques have been used to investigate the framework
stability and the removal of the guest molecules of 5
according to the sublimation properties of naphthalene. The
TGA result reveals that 5 is stable up to 180 °C where
decomposition starts, and there is a weight loss of 8.8%
(calcd: 8.0%) from ca. 180 to 210 °C, being consistent with
the removal of the included naphthalene rings, which is also
confirmed by elemental analyses (Figure 4). As shown in
Figure 4, the eclipsed open-channel frameworks are thermally
stable up to almost 300 °C, which is well confirmed by the
TGA results of complexes 1-4. The similarity between the
XRPD pattern recorded at this point and that of the original
starting sample suggests the dried solid {[Cd(TPT)L]}∞
retains the initial framework of 5. The slight shift and
splitting of some peaks may be attributed to the removal of
naphthalene rings and the subtle change of the relative
positions of some atoms in the crystal lattice (Figure 3).20
Application of a continuous solvent-area model to calculate
the channels containing diffuse electron density led to the
same result,21 suggesting a contribution of ca. 279 electrons/
unit cell from the channel region. This is consistent with ca.
three molecules, including terephthalic acid and two water
molecules per unit cell, which is also consistent with the
result of elemental analysis.
Complex 2. Similar to complex 1, the structure of 2
consists of a 2D neutral coordination network with lattice
(17) Clegg, W.; Cressey, J. T.; McCamley, A.; Straughan, B. P. Acta
Crystallogr., Sect. C 1995, 51, 234.
(18) (a) Fujita, M.; Kwon, Y. J.; Miyazawa, M.; Ogura, K. J. Chem. Soc.,
Chem. Commun. 1994, 1977. (b) Huang, S.-D.; Xiong, R.-G.
Polyhedron 1997, 16, 3929.
(19) Lu, J. Y.; Schauss, V. CrystEngComm 2001, 26, 111.
(20) Du, M.; Chen, S.-T.; Bu, X.-H. Cryst. Growth Des. 2002, 2, 625.
(21) Sluis, P. V. D.; Spek, A. L. Acta Crystallogr. 1990, A46, 194. This
was implemented as the SQUEEZE procedure in the following: Spek,
A. L. PLATON, A Multipurpose Crystallographic Tool; Utrecht
University: Utrecht, The Netherlands, 1998.
5384 Inorganic Chemistry, Vol. 43, No. 17, 2004

Eclipsed 2D Cadmium(II) Coordination Polymers
Figure 1. (a) View of the CdII coordination environment. (b) Eclipsed
2D coordination networks (different color used to show the adjacent 2D
layers). (c) Stacking diagram along the c axis (H atoms and guest molecules
omitted for clarity). (d) 2D eclipsed network with TPT and water molecules
included in the open channels of complex 1.
Figure 2. Eclipsed 2D networks of (a) 2 with the L and water molecules,
(b) 3 with mesitylene molecules and water molecules, (c) 4 with tetra-
methylbenzene molecules, and (d) 5 with naphthalene molecules included
in their open channels.
Inorganic Chemistry, Vol. 43, No. 17, 2004 5385

Zou et al.
Table 2. Structural Parameters
before SQUEEZE procedure
wR2 ∆F(max, min)
after SQUEEZE procedure
resid electrons/
unit cell
no. of
included molecules
R1
R1
wR2
∆F(max, min)
1
2
3
4
5
0.0278
0.0712
0.0520
0.0460
0.0428
0.0612
0.1949
0.1038
0.0736
0.1055
1.016, -0.436
1.669, -1.884
0.664, -0.530
0.591, -0.729
0.843, -0.361
279
193
88
550
58
1.5 GM1, H2O
GM2, 0.2 H2O
0.5 GM3, H2O
3.5GM4
0.0265
0.0437
0.0383
0.0362
0.0319
0.0587
0.0862
0.0574
0.0584
0.0660
0.534, -0.389
0.436, -0.994
0.457, -0.497
0.606, -0.667
0.596, -0.314
0.5 GM5
Figure 3. XRPD patterns for 5: (a) before removal of the guest
naphthalene molecules; (b) after removal of the guest naphthalene molecules.
Figure 5. Emission spectra of 1-5 in the solid state at room temperature
(λex ) 332 nm).
nm may be caused by the cooperated emission of TPT and
the included L. The emission spectrum of 5 is much more
complicated: four emission bands (λmax, 389, 410, 434, 485
nm; λex, 332 nm) were found, which may arise from the
emissions of TPT ligand and the included naphthalene.
Owing to the blue emission of 1-5, they may be potential
materials for blue-light-emitting diode devices. These con-
densed polymeric materials may be good candidates for ther-
mally stable and solvent-resistant blue fluorescent material
because 1-5 are insoluble in the common solvents such as
ethanol, chloroform, acetone, acetonitrile, benzene, and water.
In conclusion, five new 2D CdII coordination polymers
with the mixed ligands terephthalic acid and 3-(2-pyridyl)-
pyrazole have been prepared and structurally characterized.
Their 2D eclipsed open-channel frameworks can accom-
modate suitable guest molecules, and the structures of these
inclusion complexes display similar behaviors. The open-
channel frameworks are retained after the removal of the
guest molecules. They also exhibit strong blue emissions and
may be potentially applicable as materials for blue-light-
emitting diode devices.
Figure 4. TG-DTG patterns for 5: black line for TG (%); gray line for
DTG (% min).
During this exclusion, a subtle color change occurs, from
faint yellow to colorless. The XRPD pattern for the desol-
vated 5 has been indexed, and the cell parameters (a )
10.3343(0.020918) Å, b ) 10.39048(0.017942) Å, c )
12.12345(0.021629) Å, R ) 95.0398(0.19738)°, â )
114.4947(0.18284)°, γ ) 106.1486(0.12519)°)) compare well
with those of compound 5, further indicating that the frame-
work is maintained after the removal of the guest molecules.
Emission Properties. Complexes 1-5 exhibit significant
blue fluorescent emission. As shown in Figure 5, the emission
spectra of complexes 1-5 consist of similar broad emission
bands in the UV-vis region that extend beyond 550 nm.
The emission maxima (λmax) are 398 (1), 428 (3), and 428
nm (4) (λex ) 332 nm), respectively. The emission bands of
1, 3, and 4 reveal hypsochromic absorption and significant
enhancement of fluorescent intensities comparing with those
of free TPT and L, because of the symmetry decrease of
TPT in the two-dimensionally condensed polymeric structure.
Unlike 1, 3, and 4, the maxima emission band of 2 at 340
Acknowledgment. This work was supported by the
National Science Funds for Distinguished Young Scholars
of China (No. 20225101) and the National Natural Science
Foundation of China (No. 20373028).
Supporting Information Available: Crystallographic informa-
tion in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC049625E
5386 Inorganic Chemistry, Vol. 43, No. 17, 2004