Novel bis(4,4′-dipyridylamine) ligand with a flexible butadiyne linker: Syntheses, structures, and photoluminescence of d10 metal coordination polymers

Article abstract of DOI:10.1021/cg201655n

The design and syntheses of novel ligands are essential for developing coordination compounds with novel structures and interesting properties. In this work, we designed and synthesized a novel ligand bis(4,4′- dipyridylaminophenylene)butadiyne (L) by attaching two 4,4′-dipyridylamine moieties to a flexible butadiyne linker. Starting from this novel ligand, seven coordination polymers [Zn₂L(HCOO)₃(OH)]_n (1), [Cd₂L₂Cl₄]_n?3nDMF?3nH ₂O (2), [CdLBr₂]_n (3), [Cd₆L ₃(SO₄)₆]_n?4nMeCN (4), [Hg ₂LBr₄]_n?3nCH₂Cl ₂?nH₂O (5), [Cu₂LI₂] _n?0.5nCH₂Cl₂ (6), and [Ag ₂L(H₂O)₂]_n(NO₃) _2n?2nH₂O (7) were synthesized. Single-crystal X-ray diffraction analyses revealed that two forms of the ligand crystals, L and L?0.5DMF present straight and bent conformations, respectively, because of the flexibility of the butadiyne unit. A rich structural diversity was observed for its d¹⁰ metal complexes. Complexes 1 and 5 present ladder-like structures. In complexes 2 and 4, the ligand molecules are linked by metal atoms to afford 3D supramolecular structures. It is noteworthy that the 3D structure of complex 4 consists of interesting infinite {Cd₆(SO ₄)₆}_∞ chains, whereas complexes 3, 6, and 7 exhibit 2D network structures. Interestingly, in the crystal of complex 7, each ligand links four metal ions and each Ag ion bridges two ligands, leading to the formation of undulated 2D sheets with large cavities composed of 66-membered metallomacrocycles, which are interpenetrated by three other such 2D sheets, affording a 4-fold interpenetrated structure. In summary, the complex structures are dependent on the metal ions and the anions. In addition, the flexibility of the butadiyne moiety provides additional means for modulating the structures. Solid state photoluminescence of the free ligand and the complexes shows emission maxima within the range of 420-515 nm, which can be modulated by the conformations of the ligand in addition to the variation of the metal ions and anions, and the introduction of the butadiyne unit has a bathochromic effect.

Full text of DOI:10.1021/cg201655n

Article
pubs.acs.org/crystal
Novel Bis(4,4′-dipyridylamine) Ligand with a Flexible Butadiyne
Linker: Syntheses, Structures, and Photoluminescence of d10 Metal
Coordination Polymers
Caixia Ding,† Xing Li,‡ Yubin Ding,† Xin Li,† Seik Weng Ng,§,# and Yongshu Xie*,†
†Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai
200237, P. R. China
‡State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical
Engineering, Ningbo University, Ningbo, Zhejiang 315211, P. R. China
§Department of Chemistry, University of Malaya, 50603, Kuala Lumpur, Malaysia
#Chemistry Department, Faculty of Science, King Abdulaziz University, PO Box 80203, Jeddah, Saudi Arabia
S
* Supporting Information
ABSTRACT: The design and syntheses of novel ligands are
essential for developing coordination compounds with novel
structures and interesting properties. In this work, we designed
a n d s y n t h e s i z e d
a
n o v e l l i g a n d b i s ( 4 , 4 ′ -
dipyridylaminophenylene)butadiyne (L) by attaching two 4,4′-
dipyridylamine moieties to a flexible butadiyne linker. Starting
from this novel ligand, seven coordination polymers [Zn2L-
(HCOO)3(OH)]n (1), [Cd2L2Cl4]n·3nDMF·3nH2O (2), [CdLBr2]n (3), [Cd6L3(SO4)6]n·4nMeCN (4),
[Hg2LBr4]n·3nCH2Cl2·nH2O (5), [Cu2LI2]n·0.5nCH2Cl2 (6), and [Ag2L(H2O)2]n(NO3)2n·2nH2O (7) were synthesized.
Single-crystal X-ray diffraction analyses revealed that two forms of the ligand crystals, L and L·0.5DMF present straight and bent
conformations, respectively, because of the flexibility of the butadiyne unit. A rich structural diversity was observed for its d10
metal complexes. Complexes 1 and 5 present ladder-like structures. In complexes 2 and 4, the ligand molecules are linked by
metal atoms to afford 3D supramolecular structures. It is noteworthy that the 3D structure of complex 4 consists of interesting
infinite {Cd6(SO4)6}∞ chains, whereas complexes 3, 6, and 7 exhibit 2D network structures. Interestingly, in the crystal of
complex 7, each ligand links four metal ions and each Ag ion bridges two ligands, leading to the formation of undulated 2D
sheets with large cavities composed of 66-membered metallomacrocycles, which are interpenetrated by three other such 2D
sheets, affording a 4-fold interpenetrated structure. In summary, the complex structures are dependent on the metal ions and the
anions. In addition, the flexibility of the butadiyne moiety provides additional means for modulating the structures. Solid state
photoluminescence of the free ligand and the complexes shows emission maxima within the range of 420−515 nm, which can be
modulated by the conformations of the ligand in addition to the variation of the metal ions and anions, and the introduction of
the butadiyne unit has a bathochromic effect.
dipyridyl-amine (4,4′-dpa),5 and their derivatives6 have been
proved to be efficient building blocks in the construction of
coordination polymers with one-, two-, or three-dimensional
structures.
During the past few years, our group has utilized 2,2′-dpa and
4,4′-dpa-derived ligands, including N,N-bis(2-pyridyl)-N′,N′-
bis(4-pyridyl)-1,4-phenylenediamine (L1, Scheme 1) and
N,N,N′,N′-tetrakis(4-pyridyl)-1,4-phenylenediamine (L2,
Scheme 1), as building blocks in the construction of
coordination polymers with tunable luminescent properties.7
It can be expected that the design and utilization of similar
tetrapyridyl ligands with various sizes of extended aromatic
systems and various HOMO−LUMO gaps is a practical
INTRODUCTION
■
The design and construction of coordination polymers
containing metal ions and organic ligands have attracted
much attention not only because of their intriguing variety of
structures, but also for their potential applications in many
fields.1,2 It is well-known that inorganic−organic hybrid
coordination polymers, especially those with d10 metal centers,
exhibit photoluminescence and have potential applications as
fluorescence-emitting materials, such as light-emitting diodes
(LEDs).3 Hence, the design and synthesis of coordination
polymers containing d10 metal centers have received remarkable
attention. One of the current interesting topics in this area is to
rationally design organic ligands with efficient coordination
groups and suitable conjugated systems. In this respect, both
bridging and chelating pyridyl ligands have been intensely
investigated due to the strong coordination ability and
structural diversity. Thus, 2,2′-dipyridylamine (2,2′-dpa),4 4,4′-
Received: December 15, 2011
Revised: April 26, 2012
Published: May 23, 2012
© 2012 American Chemical Society
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Scheme 1. Structures of L1, L2, and L
added to a three-necked flask (500 mL) and heated at 130 °C under
N2 for 4 days. After the reaction was cooled, the majority of DMF was
removed by rotary evaporation. The residue was purified by a silica gel
column to afford a colorless solid of the ligand L (590 mg, yield 11%).
Crystals of L were obtained by the slow evaporation of a MeOH
solution of L for a few days at room temperature, and the crystals of
L·0.5DMF were obtained by heating a solution of L (10 mg, 0.02
mmol) in DMF (1 mL) and H2O (0.5 mL) at 120 °C, followed by
1
cooling to room temperature. H NMR (CDCl3, 400 MHz): δ = 8.46
(d, J = 6.0 Hz, 8H, pyridyl-H), 7.56 (d, J = 8.4 Hz, 4H, phenylene-H),
7.15 (d, J = 8.8 Hz, 4H, phenylene-H), 6.97 (m, 8H, pyridyl-H). Anal.
Calcd (%) for C36H24N6: C, 79.98; H, 4.47; N, 15.55. Found: C, 79.90;
H, 4.34; N, 15.62. IR (KBr pellet, cm−1): 3441(br), 3017(w),
2921(w), 2847(w), 1578(vs), 1492(s), 1402(w), 1386(w), 1338(m),
1300(m), 1281(m), 1214(m),1175(w), 989(m), 935(w), 810(m),
733(w), 695(w), 618(m), 557(w), 538(w). HRMS: obsd 541.2142,
calcd for C36H25N6 ([M + H]+): 541.2141.
approach to further tuning the fluorescence wavelength and
intensity of the coordination compounds. Thus, a novel
butadiyne-containing tetrapyridyl ligand, bis(4,4′-dipyridyl-
aminophenylene)butadiyne (L, Scheme 1) was designed.
Compared with L2, it offers some intriguing characteristics.
First, the conjugated system is extended by the butadiyne
moiety, which may be efficient to tune the fluorescence
wavelength. Second, the ligand has better flexibility due to the
bending and rotation of the butadiyne unit.8 Thus, the
conformational freedom may be better to satisfy the geometric
needs of various metal ions in the construction of novel
coordination polymers with diversified and intriguing archi-
tectures and topologies. On the basis of these considerations, in
this work, we synthesized the novel ligand L, and utilized it for
coordination with Zn(II), Cd(II), Hg(II), Cu(I), and Ag(I) to
afford coordination polymers, [Zn2L(HCOO)3(OH)]n (1),
[Cd2L2Cl4]n ·3nDMF·3nH2O (2), [CdLBr2 ]n (3),
[Cd6L3(SO4)6]n·4nMeCN (4), [Hg2LBr4]n·3nCH2Cl2·nH2O
(5), [Cu2LI2]n·0.5nCH2Cl2 (6), and [Ag2L(H2O)2]n
(NO3)2n·2nH2O (7).
Scheme 2. Preparation of Ligand L
[Zn2L(HCOO)3(OH)]n (1). A mixture of L (5.4 mg, 0.01 mmol),
Zn(ClO4)2·6H2O (7.4 mg, 0.02 mmol), and HCOONa·2H2O (4.2
mg, 0.04 mmol) in DMF, MeCN and H2O (8: 12: 1) was sealed in a
10 mL Teflon lined stainless steel vessel under autogenous pressure
and heated to 150 °C for 100 h. After cooling to room temperature,
yellowish crystals of 1 suitable for X-ray structure determination were
obtained. Yield: 4 mg, 52%. Anal. (%) Calcd for C39H28N6O7Zn2: C,
56.88; H, 3.43; N, 10.21. Found: C, 57.12; H, 3.35; N, 10.37. IR (KBr
pellet, cm−1): 3420(br), 2917(w), 2844(w), 1619(s), 1598(vs),
1497(s), 1383(m), 1347(m), 1313(m), 1217(m), 1066(m), 1025(s),
992(m), 826(m), 739(w), 634(m), 538(m).
These complexes exhibit a rich structural diversity, including
ladder-like structures, 2D networks containing (Cu2I2) units,
3D structures consisting of infinite {Cd6(SO4)6}∞ chains, and a
4-fold interpenetrated 2D structure. In addition, it is note-
worthy that two different crystals of the ligand, namely, L and
L·0.5 DMF were obtained from MeOH and DMF, respectively,
and they contain the butadiyne moieties in the straight and
bent conformations, respectively. Both conformations are also
observed in the complexes. The solid state emission maxima of
these compounds lie in the range between 420 and 515 nm,
and the emission behavior can be well tuned.
[Cd2L2Cl4]n·3nDMF·3nH2O (2). A mixture of L (5.4 mg, 0.01
mmol), Cd(NO3)2·4H2O (6.2 mg, 0.02 mmol), and NaCl (2.2 mg,
0.04 mmol) in DMSO, DMF, and H2O (12: 9: 0.5) was sealed in a
small vial (10 mL), which was heated to 120 °C for 120 h. After it was
cooled to room temperature, colorless block crystals of 2 were
obtained. Yield: 4 mg, 54%. Anal. (%) Calcd for C81H75Cd2Cl4N15O6:
C, 56.52; H, 4.39; N, 12.21. Found: C, 56.73; H, 4.28; N, 12.38. IR
(KBr pellet, cm−1): 3442(br), 2926(w), 2851(w), 1615(m), 1582(vs),
1496(vs), 1383(m), 1341(m), 1308(m), 1283(m), 1217(m),
1064(m), 1013(s), 992(s), 819(m), 736(w), 694(w), 624(m),
541(m).
[CdLBr2]n (3). Compound 3 was prepared by a procedure similar to
that for 2, using KBr (4.8 mg, 0.04 mmol) in place of NaCl. Colorless
block crystals of 3 were obtained. Yield: 5 mg, 63%. Anal. (%) Calcd
for C36H24Br2CdN6: C, 53.19; H, 2.98; N, 10.34. Found: C, 53.23; H,
2.92; N,10.42. IR (KBr pellet, cm−1): 3418(br), 2920(w), 2851(w),
1636(m), 1617(m), 1591(s), 1496(s), 1385(w), 1344(m), 1314(w),
1294(m), 1216(m), 1061(m), 1013(s), 827(w), 742(w), 627(m),
565(m), 541(m), 469(m).
[Cd6L3(SO4)6]n·4nMeCN (4). Compound 4 was prepared by a
procedure similar to that for 2 from the reaction of L (5.4 mg, 0.01
mmol) and CdSO4 (2 mg, 0.02 mmol) in DMF, MeCN, and H2O (5:
10: 1). Yellowish crystals of 4 were obtained. Yield: 5 mg, 49%. Anal.
(%) Calcd for C116H84Cd6N22O24S6: C, 45.88; H, 2.79; N, 10.15.
Found: C, 45.62; H, 2.71; N, 10.03. IR (KBr pellet, cm−1): 3433(br),
2919(w), 2847(w), 1637(m), 1613(m), 1588(s), 1495(s), 1400(s),
1384(vs), 1316(w), 1281(w), 1217(w), 1146(vs), 986(m), 941(w),
816(w), 621(m), 493(m), 467(m).
EXPERIMENTAL SECTION
■
Materials. All chemicals of reagent grade quality were used as
received from commercial sources. (4-Bromophenyl)- di(4-pyridyl)-
amine was prepared as we previously reported.7a
1
Physical Measurements. H NMR spectra were recorded on a
Bruker AVANCE spectrometer (400 MHz). FT-IR spectra were
recorded in the region of 400−4000 cm−1 on a Thermo Electron
Avatar 380 FT-IR instrument (KBr Discs). Elemental analyses were
carried out with an Elmentar Vario EL-III analyzer. Fluorescence
measurements were performed on a Varian Cary Eclipse fluorescence
spectrophotometer. HRMS were performed using a Waters LCT
Premier XE spectrometer.
S y n t h e s i s a n d C r y s t a l G r o w t h . B i s ( 4 , 4 ′ -
dipyridylaminophenylene)butadiyne (L) (4-bromo-phenyl)-di(4-
pyridyl)amine (6.52 g, 20 mmol), tetrakis(tri- phenylphosphine)
palladium (1.16 g, 1.0 mmol), cuprous iodide (400 mg, 2.1 mmol),
trimethylsilylacetylene (TMSA) (7.1 mL, 50 mmol), diisopropylamine
(33.4 mL, 237 mmol), and N,N-Dimethylformamide (270 mL) were
[Hg2LBr4]n·3nCH2Cl2·nH2O (5). A solution of Hg(NO3)2 (6 mg,
0.016 mmol) and KBr (4 mg, 0.032 mmol) in methanol (3 mL) was
layered over a solution of L (4.2 mg, 0.008 mmol) in CH2Cl2(3 mL).
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Article
Table 1. Crystallographic Data and Structure Refinements Summary for L, L·0.5DMF, and the Metal Complexes
L
L·0.5DMF
2
3
4
5
6
7
empirical
formula
C36H24N6
C39H31N7O
C81H75Cd2Cl4N15O6
C36H24Br2CdN6
C116H84Cd6N22O24S6 C19.50H16Br2
Cl3HgN3O0.50
767.11
C36.50H25Cl
Cu2I2N6
C18H16Ag
N4O5
fw
540.61
613.71
1721.16
812.83
3036.81
triclinic
963.96
476.22
crystal
system
monoclinic
triclinic
monoclinic
monoclinic
monoclinic
triclinic
monoclinic
space group
T (K)
a (Å)
P21/c
P1
P21/c
P2/n
P1
C2/c
P1
̅
298(2)
P2/n
̅
̅
298(2)
11.6529(11)
7.8862(8)
16.1128(18)
90
293(2)
298(2)
20.613(2)
12.7980(11)
18.8901(17)
90
298(2)
7.7348(7)
10.3163(11)
24.542(2)
90
298(2)
100(2)
19.6356(9
16.0764(8)
30.783(3)
90
298(2)
13.0282(13)
9.5994(8)
17.9846(17)
90
8.8313(5)
9.8210(6)
20.9307(13)
78.3320(10)
81.6130(10)
67.0860(10)
1633.02(17)
2
10.1093(12)
13.0570(13)
24.3590(19)
85.542(2)
85.314(2)
80.7490(10)
3156.1(5)
1
8.4628(12)
10.6640(15)
11.8808(19)
80.5110(10)
70.4030(10)
86.894(2)
996.3(3)
1
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
Z
98.7540(10)
90
104.4500(10)
90
90.3530(10)
90
101.453(6)
90
90.2160(10)
90
1463.5(3)
2
4825.6(8)
2
1958.2(3)
2
9523.8(11)
16
2249.2(4)
4
Dcalcd (Mg/
1.227
1.248
1.185
1.379
1.598
2.140
1.607
1.406
m3)
μ (mm−1
)
0.075
2577
0.078
5687
0.603
8493
2.628
3426
1.168
10.171
10529
2.715
3469
0.928
3482
no. of reflns
(I > 2σ(I))
Final
10968
0.0488
0.0530
0.0761
0.0731
0.0525
0.0866
0.0651
0.0776
a
R1 [I >
2σ(I)]
b
R2 (all
0.0948
1.028
0.1677
1.041
0.2387
1.035
0.1635
1.045
0.1279
1.041
0.2762
1.094
0.1597
1.083
0.2344
0.883
data)
goodness of
fit
a
b
R1 = Σ||Fo| − |Fc||/Σ|Fo|. R2 =Σ||Fo| − |Fc||w1/2/Σ|Fo|w1/2
.
Yellowish single crystals of 5 were obtained by slow interlayer diffusion
for several weeks. Yield: 3 mg, 47%. Anal. (%) Calcd for
C19.50H16Br2Cl3HgN3O0.50: C, 30.53; H, 2.10; N, 5.48. Found: C,
30.70; H, 2.04; N, 5.62. IR (KBr pellet, cm−1): 3413(br), 2974(m),
2896(w), 1638(w), 1616(w), 1590(vs), 1499(s), 1384(m), 1340(s),
1302(m), 1287(w), 1217(w), 1088(m), 1049(s), 1012(m), 937(w),
880(m), 819(w), 737(w), 647(m), 541(w), 495(w).
DFT Calculations. The calculations were carried out by using the
Gaussian03 program package.10 The geometries of L2 and L were
optimized by density functional calculations employing the hybrid
B3LYP function.11 The 6-31G* basis set12 was adopted to describe all
atoms. The calculated HOMO/LUMO energies are listed in Table S3.
Molecular structures and molecular orbitals were visualized by the
Gabedit software.13
[Cu2LI2]n·0.5nCH2Cl2 (6). Compound 6 was prepared by a
procedure similar to that for 5, using a solution of CuI (3 mg, 0.016
mmol) in MeCN in place of a methanol solution of Hg(NO3)2 and
KBr. Single crystals of 6 were obtained by slow interlayer diffusion for
RESULTS AND DISCUSSION
■
Synthesis and Characterization. The ligand L was
prepared from a one-pot synthesis comprising of a Sonogashira
coupling reaction of (4-bromophenyl)-bis(4-pyridyl)amine
with trimethylsilylacetylene (TMSA) in DMF followed by an
oxidative dimerization, using tetrakis(triphenyl-phosphine)-
palladium, cuprous iodide, and diisopropylamine as catalysts
and the base, respectively. When the reaction was performed at
80 °C, no reaction could be detected by TLC, so we tried to
increase the reaction temperature. Thus the reaction was
performed at 130 °C for 4 days to afford L. At first, in the
reaction, the single-ethyne product was formed, then the
alkynyl group is successively transferred from silicon to copper
to generate alkynylcopper species, which then oxidatively
dimerize to furnish the diacetylene compound L.14 It is
noteworthy that two forms of ligand crystals were obtained by
two different methods: the form of L was obtained by slow
evaporation of the MeOH solution at room temperature, and
the form of L·0.5DMF was obtained by heating the ligand in a
mixed solvent of DMF and H2O followed by cooling to room
temperature. Single crystals of complexes 1−4 were obtained
by solvothermal reactions of the corresponding metal salts with
the ligand L and the crystals of complexes 5−7 were obtained
by slow interlayer diffusion between the solutions of the ligand
and corresponding metal salts. Thus, the two different ligand
several weeks. Yield:
4 mg, 55%. Anal. (%) Calcd for
C36.50H25ClCu2I2N6: C, 45.48; H, 2.61; N, 8.72. Found: C, 45.73; H,
2.68; N, 8.85. IR (KBr pellet, cm−1): 3415(br), 2917(m), 2847(w),
1637(m), 1617(s), 1590(s), 1559(w), 1489(s), 1400(w), 1384(s),
1337(w), 1285(w), 1212(m), 1014(w), 820(w), 736(w), 627(m),
476(m).
[Ag2L(H2O)2]n(NO3)2n·2nH2O (7). A solution of L (4.2 mg, 0.008
mmol) in methanol (3 mL) was layered over a solution of AgNO3 (6
mg, 0.016 mmol) in H2O (3 mL). Single crystals of 7 were obtained by
slow interlayer diffusion for several weeks. Yield: 5 mg, 66%. Anal. (%)
Calcd for C18H16AgN4O4.5: C, 46.17; H, 3.44; N, 11.97. Found: C,
46.42; H, 3.36; N, 12.08. IR (KBr pellet, cm−1): 3447(br), 2920(m),
2847(w), 1614(m), 1589(s), 1492(s), 1384(vs), 1342(m), 1309(m),
1287(w), 1219(w), 1146(w), 993(m), 938(w), 820(m), 723(w),
618(m).
X-ray Crystallography. X-ray diffraction data were collected on a
Bruker-AXS APEX diffractometer utilizing MoKα radiation (λ =
0.71073 Å). The structures were solved by direct methods and refined
with full-matrix least-squares technique. Anisotropic thermal param-
eters were applied to all non hydrogen atoms. All of the hydrogen
atoms in these structures are located from the differential electron
density map and constrained to the ideal positions in the refinement
procedure. All calculations were performed using SHELX-97 software
package.9 Crystal data and experimental details for the crystals are
summarized in Table 1 and S1, and selected bond lengths and bond
angles are given in Table 2 and S2.
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Article
Table 2. Selected Bond Lengths (Å) and Angles (deg) for the Metal Complexes 2−7
complex 2
Cd(1)−N(2)
Cd(1)−N(6)
Cd(1)−N(5)
Cd(1)−N(3)
Cd(1)−Cl(2)
Cd(1)−Cl(1)
2.364(7)
2.382(7)
2.393(8)
2.400(8)
2.600(3)
2.630(3)
N(2)−Cd(1)−N(6)
N(2)−Cd(1)−N(5)
N(6)−Cd(1)−N(5)
N(2)−Cd(1)−N(3)
N(6)−Cd(1)−N(3)
N(5)−Cd(1)−N(3)
179.5(3)
92.3(3)
87.3(3)
90.3(3)
90.1(3)
176.8(2)
N(2)−Cd(1)−Cl(2)
N(6)−Cd(1)−Cl(2)
N(5)−Cd(1)−Cl(2)
N(3)−Cd(1)−Cl(2)
N(2)−Cd(1)−Cl(1)
90.1(2)
90.0(2)
93.1(2)
88.7(2)
88.7(2)
N(6)−Cd(1)−Cl(1)
N(5)−Cd(1)−Cl(1)
N(3)−Cd(1)−Cl(1)
Cl(2)−Cd(1)−Cl(1)
91.1(2)
89.4(2)
88.8(2)
177.26(9)
a
complex 3
Cd(1)−N(3)#1
Cd(1)−N(3)#2
Cd(1)−N(2)
Cd(1)−N(2)#3
Cd(1)−Br(1)#3
Cd(1)−Br(1)
2.382(8)
2.382(8)
2.400(8)
2.400(8)
2.7470(14)
2.7470(14)
N(3)#1−Cd(1)−N(3)#2
N(3)#1−Cd(1)−N(2)
N(3)#2−Cd(1)−N(2)
N(3)#1−Cd(1)−N(2)#3
N(3)#2−Cd(1)−N(2)#3
N(2)−Cd(1)−N(2)#3
92.7(4)
N(3)#1−Cd(1)−Br(1)#3
N(3)#2−Cd(1)−Br(1)#3
N(2)−Cd(1)−Br(1)#3
N(2)#3−Cd(1)−Br(1)#
N(3)#1−Cd(1)−Br(1)
88.3(2)
N(2)−Cd(1)−Br(1)
N(2)#3−Cd(1)−Br(1)
Br(1)#3−Cd(1)−Br(1)
92.1(3)
87.1(3)
174.5(4)
90.5(3)
90.5(3)
174.5(4)
86.7(4)
92.4(2)
87.1(3)
92.1(3)
92.4(2)
88.3(2)
178.96(9)
N(3)#2−Cd(1)−Br(1)
b
complex 4
Cd(1)−O(5)
Cd(1)−O(12)#1
Cd(1)−N(5)
Cd(1)−O(1)
Cd(1)−N(2)
Cd(1)−O(9)
Cd(2)−O(8)#2
Cd(2)−O(9)
Cd(2)−N(3)
Cd(2)−O(6)
Cd(2)−O(2)
Cd(2)−O(1)
Cd(3)−N(6)#3
Cd(3)−N(8)
Cd(3)−O(10)
2.263(5)
2.271(5)
2.295(6)
2.329(4)
2.345(5)
2.441(4)
2.185(5)
2.248(4)
2.302(6)
2.313(5)
2.331(4)
2.590(5)
2.282(6)
2.345(6)
2.348(6)
Cd(3)−O(3)#2
Cd(3)−O(6)#2
Cd(3)−O(7)#2
O(5)−Cd(1)−N(2)
O(12)#1−Cd(1)−N(2)
N(5)−Cd(1)−N(2)
O(1)−Cd(1)−N(2)
O(5)−Cd(1)−O(9)
O(12)#1−Cd(1)−O(9)
N(5)−Cd(1)−O(9)
O(1)−Cd(1)−O(9)
N(2)−Cd(1)−O(9)
O(8)#2−Cd(2)−O(9)
O(8)#2−Cd(2)−N(3)
2.350(5)
O(9)−Cd(2)−N(3)
96.6(2)
N(6)#3−Cd(3)−O(7)#2
N(8)−Cd(3)−O(7)#2
O(9)−Cd(2)−O(6)
N(3)−Cd(2)−O(6)
O(8)#2−Cd(2)−O(2)
O(9)−Cd(2)−O(2)
N(3)−Cd(2)−O(2)
O(6)−Cd(2)−O(2)
O(8)#2−Cd(2)−O(1)
O(9)−Cd(2)−O(1)
N(3)−Cd(2)−O(1)
O(6)−Cd(2)−O(1)
O(2)−Cd(2)−O(1)
N(6)#3−Cd(3)−N(8)
77.14(19)
163.7(2)
2.448(5)
2.530(6)
O(8)#2−Cd(2)−O(6)
O(10)−Cd(3)−O(7)#2
O(3)#2−Cd(3)−O(7)#2
O(6)#2−Cd(3)−O(7)#2
N(6)#3−Cd(3)−O(10)
N(8)−Cd(3)−O(10)
N(6)#3−Cd(3)−O(3)#2
N(8)−Cd(3)−O(3)#2
O(10)−Cd(3)−O(3)#2
N(6)#3−Cd(3)−O(6)#2
N(8)−Cd(3)−O(6)#2
O(10)−Cd(3)−O(6)#2
O(3)#2−Cd(3)−O(6)#2
102.30(18)
111.98(19)
89.65(18)
56.25(16)
138.6(2)
83.0(2)
83.82(17)
167.30(18)
104.71(17)
133.67(16)
89.21(19)
81.49(17)
161.97(16)
76.67(15)
88.14(17)
79.58(15)
57.56(15)
87.3(2)
86.74(18)
88.22(19)
108.7(2)
87.17(18)
80.65(17)
106.10(16)
84.44(18)
78.28(15)
159.51(18)
121.32(17)
88.4(2)
88.78(19)
85.0(2)
129.9(2)
132.45(18)
137.7(2)
74.73(18)
82.58(16)
c
complex 5
Hg(1)−N(1)
Hg(1)−N(6)#1
Hg(1)−Br(1)
Hg(1)−Br(2)
Hg(2)−N(4)#2
Hg(2)−N(3)
2.386(13)
2.416(14)
2.492(2)
2.500(2)
2.340(15)
2.350(13)
Hg(2)−Br(3)
Hg(2)−Br(4)
N(4)−Hg(2)#2
N(6)−Hg(1)#1
N(1)−Hg(1)−N(6)#1
N(1)−Hg(1)−Br(1)
2.510(2)
2.517(2)
2.340(15)
2.416(14)
89.7(4)
N(6)#1−Hg(1)−Br(1)
N(1)−Hg(1)−Br(2)
N(6)#1−Hg(1)−Br(2)
Br(1)−Hg(1)−Br(2)
N(4)#2−Hg(2)−N(3)
100.4(3)
100.2(3)
99.4(3)
N(4)#2−Hg(2)−Br(3)
N(3)−Hg(2)−Br(3)
N(4)#2−Hg(2)−Br(4)
N(3)−Hg(2)−Br(4)
Br(3)−Hg(2)−Br(4)
107.1(4)
102.6(4)
98.8(4)
149.80(7)
103.3(5)
99.6(3)
140.60(7)
102.5(3)
d
complex 6
Cu(1)−N(3)#1
Cu(1)−N(2)
Cu(1)−I(1)#2
2.040(7)
2.066(7)
2.6273(15)
Cu(1)−I(1)
I(1)−Cu(1)#2
N(3)#1−Cu(1)−N(2)
N(3)#1−Cu(1)−I(1)#2
2.7139(18)
2.6273(15)
N(2)−Cu(1)−I(1)#2
N(3)#1−Cu(1)−Cu(1)#2
N(2)−Cu(1)−Cu(1)#2
108.8(2)
N(3)#1−Cu(1)−I(1)
N(2)−Cu(1)−I(1)
I(1)#2−Cu(1)−I(1)
Cu(1)#2−I(1)−Cu(1)
103.6(2)
100.1(3)
120.61(5)
59.39(5)
128.3(2)
119.9(2)
61.94(5)
110.6(3)
112.3(2)
I(1)#2−Cu(1)−Cu(1)#2
e
complex 7
2.687(14)
159.3(3)
Ag(1)−N(3)
Ag(1)−N(2)
2.139(7)
2.156(6)
Ag(1)−O(1)
N(3)−Ag(1)−N(2)
N(2)−Ag(1)−O(1)
96.7(4)
N(3)−Ag(1)−O(1)
103.4(4)
a
Symmetry transformations used to generate equivalent atoms: #1 −x + 5/2, y + 1, −z + 1/2; #2 x, y + 1, z #3 − x + 5/2, y, −z + 1/2; #4 x, y − 1, z;
b
#5 −x, −y, −z + 1. Symmetry transformations used to generate equivalent atoms: #1 −x + 1, −y + 1, −z + 1; #2 −x + 2, −y + 1, −z + 1; #3 −x + 1,
c
−y + 2, −z + 1; #4 x, y − 1, z; #5 −x + 2, −y, −z + 1; #6 −x + 1, −y, −z; #7 x, y + 1, z; #8 x − 1, y, z − 1; #9 x + 1, y, z + 1. Symmetry
d
transformations used to generate equivalent atoms: #1 −x + 3/2, −y + 5/2, −z + 1; #2 −x + 5/2, −y + 5/2, −z + 1. Symmetry transformations
used to generate equivalent atoms: #1 x, y − 1, z; #2 −x + 2, −y, −z + 1; #3 −x, −y + 2, −z + 2; #4 x, y + 1, z; #5 −x − 1, −y + 1, −z + 2.
e
Symmetry transformations used to generate equivalent atoms:#1 x + 1/2, −y + 1, z + 1/2; #2 −x + 1/2, y, −z + 3/2; #3 −x + 1/2, y, −z + 1/2; #4
−x + 1, −y − 1, −z + 2; #5 x − 1/2, −y + 1, z − 1/2.
crystals and complexes 1−7 were characterized by single-crystal
X-ray diffraction analyses.
angles between the phenylene and the pyridyl rings are 70.0(8)
and 70.3(5)°, respectively. The butadiyne unit of L adopts an
approximately straight line conformation.
In the crystal of L·0.5 DMF, the butadiyne unit and the two
phenylene moieties are nonplanar (Figure 1b), which is in
sharp contrast to the planar structure observed in the crystal of
L obtained from MeOH. The two phenylene rings are
approximately vertical, with the dihedral angle of 90.4(1)°.
Crystal Structures of L and L·0.5DMF. The molecule of
ligand L in the crystal obtained from MeOH is centrosym-
metric (Figure 1a). The butadiyne unit and the phenylene
moieties are coplanar, and the dpa moieties are deviated from a
planar structure due to steric hindrance. The dihedral angle
between the neighboring pyridyl rings is 54.1(1)°, and the
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Figure 2. (a) View showing coordination environments of the Cd(II)
centers in complex 2 with thermal ellipsoids at the 50% probability
level. DMF and water have been omitted for clarity. (b) A 3D
coordination network of complex 2. (c) Topological view of 2.
Figure 1. Molecular structures with thermal ellipsoids at the 50%
probability level for L (a) and L·0.5DMF (b). Hydrogen atoms and
DMF molecules are omitted for clarity. (c) The figure showing the
angle δ for describing the bending of the butadiyne unit. (d) An
[L(DMF)]2 dimeric unit in the crystal of L·0.5DMF formed by
intermolecular hydrogen bonds and π···π interactions.
2.400(8) Å, and 2.600(3)−2.630(3) Å, respectively. These
values lie within the normal range for Cd−N and Cd−Cl
lengths in similar complexes.7,16 Each Cd(II) links four ligands
and each ligand links four Cd(II), which can be simplified as
four−connected nodes, thus, affording a well-known uninodal
cds net, which is interpenetrated by another such cds net,
affording a 2-fold interpenetrated structure. Alternatively, the
central N atoms of dpa units and the Cd(II) ions can be
considered as 3- and 4-connected nodes, respectively, thus, the
structure of 2 is a three-dimensional 2-fold interpenetrated
And the butadiyne unit adopt a bent conformation. The
bending can be described by the angle δ between the single
bonds attached to the butadiyne unit (Figure 1c). Thus, for a
straight conformation, the δ value is 180°, and for bent
conformations, δ will be smaller than 180°. The δ value in the
crystal of L·0.5 DMF was found to be 155.4(3)°, indicating a
severe distortion of the butadiyne unit, which may result in a
decrease in the π conjugation system and a blue shift of the
emission peaks (vide infra). Interestingly, hydrogen bonds are
observed between the pyridyl N atoms of the 4,4′-dpa moieties
and the phenylene H atoms of neighboring ligand molecules,
with the H···N distances of 2.51 Å, and the C−H···N angles of
153°. In addition, slipped parallel π···π stacking interactions
between the pyridyl rings are observed, with the interplane
angles of 23.2(4)°, and the centroid···centroid distances of 4.58
Å. These values lie above the optimal distance for π···π
stacking.15 Thus, the two ligand molecules are linked to afford a
dimeric structure. It is noteworthy that the dimer is also
involved in intermolecular hydrogen bonds with two DMF
molecules, with the H···O distances of 2.40 Å and the C−H···O
angles of 166°, thus a [L (DMF)]2 dimer is formed. Hence, the
wide occurrence of intermolecular hydrogen bonds and π···π
interactions may account for the severe distortion of the
butadiyne unit.
network with the Schlafli symbol of {83} {85;10}, which was
̈
2
obtained by TOPOS417(Figure 2c).
Crystal Structure of [CdLBr2]n (3). In the crystal structure
of complex 3 (Figure 3), the coordination environment of each
Figure 3. 2D coordination network of 3.
The presence of different conformations of L may provide an
efficient approach for the construction of diversified and
intriguing coordination architectures and topologies, which is
demonstrated by the following crystal structures.
Crystal Structure of [Zn2L(HCOO)3(OH)]n (1). The crystal
data quality for complex 1 is relatively poor with an R1 value of
0.1198, which cannot be significantly lowered even after
repeated crystal growth and X-ray diffraction measurements. It
shows a rough ladder-like structure (Supporting Information
Figure S3). Related data are summarized in Supporting
Information Table S1 and S2.
Crystal Structure of [Cd2L2Cl4]n·3nDMF·3nH2O (2).
Crystal structure of compound 2 is shown in Figure 2. L
utilizes all its pyridyl nitrogens to coordinate with four Cd(II)
atoms. Each Cd(II) has a distorted octahedral coordination
geometry, with four pyridyl nitrogens coordinated in the
equatorial plane and two chlorides coordinated at the axial
positions, which is different from the tetrahedral coordination
geometry of Zn(II) observed in complex 1. The L ligands adopt
embowed conformations with the δ value of 168.3(1)°, and the
Cd−N and Cd−Cl bond lengths lie in the ranges of 2.364(7)−
Cd(II) is octahedral, which is similar to that observed in
complex 2, except the coordination of bromine in place of
chlorine atoms. Cd−N distances are 2.382(8) and 2.400(8) Å,
similar to those observed in complex 2. Cd−Br distance is
2.7470(14) Å, which is within the typical Cd−Br bond length
range as previously reported.18 The ligand L adopts an
approximately straight conformation, and the ligand molecules
are linked by Cd atoms to form 46- and 20-membered
metallomacrocycles, with the closest Cd···Cd distances of 22.98
and 10.32 Å, respectively. These metallomacrocycles are
interconnected to afford a 2-D network. The structural
difference between 2 and 3 may be caused by the difference
in the anions, and it may also be ascribed to the difference in
the conformations of the ligands. Both Cd(II) atoms and
ligands are four−connected. Thus, the topology of 3 can be
described as a uninodal 44-sql net. Alternatively, the central N
atoms of dpa units can be considered as three-connected nodes
and Cd(II) can be treated as four-connected nodes. On the
basis of this simplification, the topology of 3 is a (3,4)-
connected two-dimensional network with the Schlafli symbol of
̈
{4; 62}2{42; 62; 82} (Supporting Information Figure S4).
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Crystal Structure of [Cd6L3(SO4)6]n·4nMeCN (4). Com-
plex 4 was obtained from the reaction of L and CdSO4 in
CH3CN and DMF. It has an interesting Cd6(SO4)6 core
structure (Figure 4a) which consists of three different types of
Figure 5. Ladder-like structure approximately along the c axis in the
crystal of complex 5. Symmetry operations: (a) −x − 1/2, −y + 1/2, −
z + 1; (b) −x + 1/2, −y + 1/2, −z + 1.
also be caused by the presence of the embowed conformation.
Thus, two different 46-membered metallomacrocycles are
formed with the distances of 22.78 Å and 21.59 Å for
Hg1···Hg1a and Hg2···Hg2b, respectively. Finally, these
metallomacrocycles are linked to afford a ladder-like structure
approximately along the c axis.
Crystal structure of [Cu2LI2]n·0.5nCH2Cl2 (6). The
structure of complex 6 is shown in Figure 6. The coordination
Figure 4. (a) {Cd6(SO4)6}∞ chains in complex 4. Symmetry
operations: (a) −x + 1, −y + 1, −z + 1; (b) −x + 2, −y + 1, −z +
1. (b) Topological view of 4.
crystallographically independent Cd(II) atoms. Cd1, Cd2, and
Cd3 atoms have similar distorted octahedral coordination
geometries. Cd1 coordinates with two pyridyl nitrogens from
two L ligands and four O atoms from four sulfate anions, Cd2 is
ligated by five O atoms from four different sulfate anions and
one pyridyl nitrogen from L, and Cd3 is coordinated by two
pyridyl nitrogens from two L ligands, two O atoms from two
sulfate anions and two O atoms from one chelating sulfate
anion. The Cd−N distances for the pyridyl groups and the
Cd−O distances for sulfate anions lie in the ranges of
2.282(6)−2.345(5) Å and 2.185(5)−2.590(5)Å, respectively.
One of the interesting structural aspects of this compound is
the rich coordination modes of the sulfates, including two
tridentate sulfates (S1 and S3) and one tetradentate sulfate
(S2), which binds four Cd atoms within one Cd6 unit. The
average S−O distance of 1.434 Å for the noncoordinated
oxygens are shorter than that of 1.471 Å for the coordinated
oxygens, which is consistent with previous observations.19 The
tridentate sulfate of S3 bridges two neighboring Cd6(SO4)6
cores, thus affording infinite {Cd6(SO4)6}∞ chains, which are
further bridged by the L ligands to form a 3D coordination
framework (Figure 4b). To the best of our knowledge, it is the
first example of a complex incorporating hexanuclear
Cd6(SO4)6 clusters as building blocks to form a 3D network
structure. Topologically, the ligands can be treated as 3- and 4-
connectors, and the complex structure can be simplified by
TOPOS417 using cluster representation, resulting in a new
Figure 6. 2D network of 6 with two different metallomacrocycles.
sphere around each Cu(I) center is composed of two pyridyl N
atoms and two iodine anions, with Cu−N bond lengths of
2.040(7) and 2.066(7) Å, and Cu−I bond lengths of 2.714(2)
and 2.627(2) Å. These bond lengths are comparable to those
observed in similar complexes.20
Two neighboring Cu(I) atoms are bridged by two iodides
with the Cu(I)−I−Cu(I) bridging angles of 120.61(5)°, thus
affording Cu2I2 units, which are further linked by the
tetrapyridyl L ligands to form a 2D coordination network
composed of 46- and 24-membered metallomacrocycles. Cu2I2
units can be simplified as four-connected cluster nodes, thus the
topology of 6 is a uninodal 44-sql net, which is similar to that of
complex 3.
Crystal Structure of [Ag2L(H2O)2]n(NO3)2n·2nH2O (7).
The crystallographic asymmetric unit of complex 7 (Figure 7)
comprises a [Ag2L]2+ cation, two weakly coordinated water
8,9,12 -connected topological net with the Schlafli symbol of
̈
{310;414;54}{314;414;58}{315;424;526;6}.
Crystal Structure of [Hg2LBr4]n·3nCH2Cl2·nH2O (5). The
asymmetric unit of crystal 5 (Figure 5) consists of two
crystallographically independent Hg(II) atoms and each Hg(II)
atom locates in a distorted tetrahedral coordination environ-
ment, provided by two bromides and two pyridyl nitrogen
atoms. The ligands show embowed conformations with the δ
value of 168.0(1)°. Hg2−N distances are 2.340(15) and
2.350(13) Å, which are significantly shorter than those of
2.386(13) and 2.416(14) Å for Hg1−N distances, which may
Figure 7. (a) Coordination mode of ligand L in complex 7. (b) An
undulated 2D network with large cavities (c) A 4-fold interpenetrated
2D structure of 7.
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molecules and two noncoordinated nitrate anions. Each Ag(I)
atom is coordinated to two N atoms from two L ligands with
the Ag−N bond lengths of 2.156(6) and 2.139(7) Å, and N−
Ag−N bond angle of 159.3(3)°. Distortion of the N−Ag−N
moiety from an ideal line is related to the weak coordination of
a water molecule with the Ag−O bond length of 2.684(1) Å.
The final coordination geometry around Ag(I) is approximately
T-shaped with O−Ag−N angles of 103.4(4) and 96.7(4)°.
Thus, each L ligand links four Ag(I) ions and each Ag(I) ion
links two L ligands, resulting in the formation of undulated with
large cavities composed of 66-membered metallomacrocycles.
Topologically, the central N atoms of dpa units can be
considered as three-connected nodes and the 2D sheet can be
described as a typical 63-hcb net, which is interpenetrated by
three other such 63-hcb nets, affording a 4-fold interpenetrated
structure.
probably due to the differences of anions and coordination
environment around the central metal ions, because photo-
luminescent behavior is closely associated with the local
environments around metal ions.25 Furthermore, the bent
conformation of the ligands observed in complex 2 may also
cause a blue shift of the emission band due to the decrease of
the π conjugation system. Therefore, the emission at a longer
wavelength is observed for 3, as compared to that of 2. The
emissions of complexes 2 and 3 are significantly weaker than
that of L, which may be ascribed to the heavy-atom effect.26
Obviously, the emission bands of 4 centered 442 nm also can
be attributed to the intraligand transitions because of its
similarity with that of L.24c,27
It is noteworthy that the intensity for 4 is stronger than that
of the ligand, which may be related to the suppression of
nonemissive energy-loss mechanism, probably induced by the
better rigidity imparted by the tethering of the {Cd6(SO4)6}∞
chain motifs. Complex 5 in the solid state exhibits a slightly
blue-shifted emission band (λmax = 437 nm) with respect to the
free L ligand. This observation is similar to that for complex 1,
and it also may be related to the bent conformation of the
ligands, similar to that observed in complex 1. In contrast to
these compounds, no clear luminescence was detected for 6
and 7, which may be related to the heavy atom effect.
Photoluminescence. Coordination polymers with d10
metal centers and conjugated organic linkers have potential
applications in various areas such as luminescent materials and
chemical sensors.21 Hence, the solid state photoluminescence
properties of complexes 1−7, together with the crystalline
samples of the free ligand L and L·0.5DMF were investigated at
room temperature (Figure 8). The free ligand L exhibits a
Compared to our previously reported ligand L2 (Scheme 1)
and its corresponding complexes, the emission peaks of L and
its complexes 2, 3, 5 exhibit red shifts of 46, 61, 44, and 23 nm,
respectively. This observation is consistent with our expectation
of increasing the emission wavelength by extending the π
conjugation system through the introduction of a butadiyne
unit, and it is consistent with the calculated values of HOMO−
LUMO energy gaps of 4.44 and 3.45 ev for L2 and L,
respectively (Supporting Information Table S3 and Figure S5).
CONCLUSIONS
■
One novel tetrapyridyl ligand bis(4,4′-dipyridylamino-
phenylene)butadiyne (L) containing a butadiyne unit was
prepared and used to coordinate with d10 metals, including
Zn(II), Cd(II), Hg(II), Cu(I) and Ag(I) to afford a rich variety
of complexes. The crystals of 1 and 5 exhibit ladder-like
structures with the embowed-conformation ligands. 2 exhibits a
2-fold interpenetrated 3D network, and 4 exhibits a 3D
coordination network consisting of infinite {Cd6 (SO4)6}∞
chains. Complexes 3, 6, and 7 exhibit 2D structures, in which
3 consists of 46- and 20-membered metallomacrocycles, 6 is
composed of 46- and 24-membered metallomacrocycles, and 7
exhibit 4-fold interpenetrated 2D sheets with the cavities
composed of 66-membered metallomacrocycles. The photo-
luminescence measurements illustrated that L, L·0.5DMF and
complexes 1−7 exhibited emissions with the maxima wave-
lengths varying in a large range of 420−515 nm. The variation
in emission intensities and wavelengths can be rationalized in
terms of the metal centers, the anions, the extended aromatic
systems and the flexible butadiyne units. The conformational
flexibility of the butadiyne moiety was observed, which provides
additional means for modulating the structures and luminescent
properties. Furthermore, it can be expected that design and
utilization of similar tetrapyridyl ligands with the butadiyne unit
connected to the pyridine rings in stead of the N atom is a
practical approach of further extending the aromatic systems to
further tune the fluorescence wavelength and intensity, which is
underway in our lab.
Figure 8. Emission spectra of L, L·0.5DMF, and compounds 1−7 in
the solid state at room temperature.
medium-intensity emission centered at 457 nm upon excitation
at 330 nm, which may be attributed to the π* → π transition.22
In contrast, the main peak for L·0.5DMF is blue-shifted to a
λmax of 420 nm, which may result from a decrease in the π
conjugation system caused by the bent conformation observed
its crystal structure (vide supra).
For complex 1, intense emission band is observed at 444 nm,
upon excitation at 310 nm, which is blue-shifted as compared to
that of L. Considering the bent conformation of the ligand in
this complex, it is more reasonable to compare it with L·0.5
DMF, which has a similar bent conformation. Thus, the
emission at 444 nm is red-shifted compared to that of 420 nm
for L·0.5 DMF. This result is consistent with previous
observations.7a Complexes 2 and 3 in the solid state have
very broad emission bands with λmax values of 496 and 515 nm,
respectively, which are red-shifted, as compared with the
corresponding values of the ligand crystals. Because the Cd(II)
ions are difficult to oxidize or to reduce, the emissions of 2 and
3 are neither metal-to-ligand charge transfer (MLCT) nor
ligand-to-metal charge transfer (LMCT) in nature.23
As a result, the emissions may be tentatively attributed to the
intraligand transitions.24 It is clear that a further red shift of the
emission occurs for 3, compared with complex 2, which is
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Wang, R. Y.; Song, D. T.; Ball, S. J.; McLean, A. B.; Wang, S. N.
Chem.Eur. J. 2005, 11, 832.
ASSOCIATED CONTENT
■
S
* Supporting Information
(5) (a) Sposato, L. K.; Nettleman, J. H.; Braverman, M. A.;
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J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.;
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J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.;
Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.;
Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.;
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Crystallographic information files (CIF format), the crystal
information of complex 1, the calculated HOMO/LUMO
energies of L2 and L, NMR spectra and HRMS of L, and part of
the crystal figures. This material is available free of charge via
the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: yshxie@ecust.edu.cn.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was financially supported by NSFC (21072060), the
Program for Professor of Special Appointment (Eastern
Scholar) at Shanghai Institutions of Higher Learning, Program
for New Century Excellent Talents in University (NCET),
Innovation Program of Shanghai Municipal Education
Commission, the Fundamental Research Funds for the Central
Universities (WK1013002), and SRFDP (20100074110015).
S.W. Ng is grateful for support by the University of Malaya
(UM.C/625/1/HIR/033/10).
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