E. Shyu et al. / Inorganica Chimica Acta 362 (2009) 2283–2292
2291
4.5. Thermogravimetric analysis
synthetic explorations towards dpa-based divalent metal carboxyl-
ate coordination polymers are underway in our laboratory.
All three coordination polymers were subjected to thermogravi-
metric analysis under flowing N2 to probe their dehydration and
decomposition behavior. TGA traces for 1–3 are shown in Figs.
S1–S3. Dehydration of compound 1 occurred slowly between
25 °C and ꢃ150 °C (mass loss 3.7%, calc. for 1 equiv. of water
3.8%). Removal of the organic components occurred between
ꢃ280 °C and ꢃ600 °C, with a mass loss of 69.4% roughly corre-
sponding to the ejection of the dpa and hmph ligands (72.8% calc.).
The mass remnant of 26.3% at ꢃ600 °C matches well for the depo-
sition of CdO (25.0% predicted).
Compound 2 also underwent slow dehydration from 25 °C to
ꢃ220 °C, with a 6.2% mass loss that is roughly consistent with
the ejection of the water molecules (5.4% predicted). Removal of
the organic components occurred between ꢃ220 °C and ꢃ640 °C.
The mass remnant at ꢃ640 °C is 31.0%, indicating a mixture of
CdO (22.0% predicted) and uncombusted organics. Compound 3
underwent dehydration between 25 °C and ꢃ65 °C, with a mass
loss roughly corresponding to loss of two water molecules of crys-
tallization (6.0% mass loss observed, 7.2% predicted). It is likely that
some of the co-crystallized water had left the sample upon stand-
ing. Ejection of the organic components occurred between ꢃ370 °C
and ꢃ650 °C, as marked by a series of mass losses totaling 66% of
the original mass, corresponding to the expulsion of one equivalent
of both iph and dpa ligands (66.8% predicted). The 26.7% mass rem-
nant at 650 °C matches well with the deposition of CdO (25.5%
predicted).
Acknowledgments
Funding for this work was provided by Michigan State Univer-
sity and the donors of the American Chemical Society Petroleum
Research Fund. E.S. thanks the MSU High School Honors Science
Program and Dr. Gail Richmond for his participation in the re-
search. We thank Dr. Rui Huang for performing the elemental anal-
yses and Dr. Kathryn Severin for use of the fluorimeter. We also
thank Dr. Wayne Ouellette of Syracuse University for the gas
absorption studies.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
References
[1] (a) H. Li, M. Eddaoudi, M. O’Keeffe, O.M. Yaghi, Nature 402 (1999) 276;
(b) R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.U. Belosludov, T.C.
Kobayashi, H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436
(2005) 238;
(c) L. Pan, D. Holson, L.R. Ciemnolonski, R. Heddy, J. Li, Angew. Chem., Int. Ed.
45 (2006) 616;
(d) N.L. Rosi, J. Eckert, M. Eddaoudi, D.J. Vodak, J. Kim, M. O’Keeffe, O.M. Yaghi,
Science 300 (2003) 1127;
(e) M. Dinca, A.F. Yu, J.R. Long, J. Am. Chem. Soc. 128 (2006) 8904;
(f) G. Ferey, M. Latroche, C. Serre, F. Millange, T. Loiseau, A. Percheron-Guegan,
Chem. Commun. (2003) 2976;
4.6. Luminescent behavior of 1–3
(g) X. Zhao, B. Xiao, A.J. Fletcher, K.M. Thomas, D. Bradshaw, M.J. Rosseinsky,
Science 306 (2004) 1012.
[2] (a) J.S. Seo, D. Whang, H. Lee, S.I. Jun, J. Oh, Y.J. Jeon, K. Kim, Nature 404 (2000)
982;
(b) B. Chen, C. Liang, J. Yang, D.S. Contreras, Y.L. Clancy, E.B. Lobkovsky, O.M.
Yaghi, S. Dai, Angew. Chem., Int. Ed. 45 (2006) 1390;
(c) O.M. Yaghi, H. Li, T.L. Groy, J. Am. Chem. Soc. 118 (1996) 9096;
(d) O.M. Yaghi, C.E. Davis, G. Li, H. Li, J. Am. Chem. Soc. 119 (1997) 2861.
[3] (a) Q.-R. Fang, G.-S. Zhu, M. Xue, J.-Y. Sun, S.-L. Qiu, Dalton Trans. (2006)
2399;
Irradiation of complexes 1–3 with ultraviolet light (k = 300 nm)
in the solid state resulted in blue-violet visible light emission in all
cases (Fig. 10). As in other cadmium-based coordination polymers
[27], the emissive behavior is plausibly ascribed to ligand-centered
p p electronic transitions within the molecular orbital systems of
ꢁ
the aromatic dicarboxylate and/or the dpa ligands. The breadth of
the emission features for 1 and 2 is attributed to intensity dimin-
ishing vibrational modes provided by the flexible pendant arms
of the hmph or 1,3-phda ligands. The greater rigidity of the iph li-
gands in 3 could potentially minimize radiative energy loss path-
ways, resulting in a narrower and more intense luminescence
spectral profile.
(b) X.-M. Zhang, M.-L. Tong, H.K. Lee, X.-M. Chen, J. Solid State Chem. 160
(2001) 118;
(c) O.M. Yaghi, H. Li, T.L. Groy, Inorg. Chem. 36 (1997) 4292.
[4] (a) N. Guillou, P.M. Forster, Q. Gao, J.S. Chang, M. Nogues, S.-E. Park, A.K.
Cheetham, G. Ferey, Angew. Chem., Int. Ed. 40 (2001) 2831;
(b) C.-D. Wu, A. Hu, L. Zhang, W. Lin, J. Am. Chem. Soc. 127 (2005) 8940;
(c) H. Han, S. Zhang, H. Hou, Y. Fan, Y. Zhu, Eur. J. Inorg. Chem. (2006) 1594;
(d) W. Mori, S. Takamizawa, C.N. Kato, T. Ohmura, T. Sato, Micropor. Mesopor.
Mater. 73 (2004) 15.
[5] (a) S. Zang, Y. Su, Y. Li, Z. Ni, Q. Meng, Inorg. Chem. 45 (2006) 174;
(b) L. Wang, M. Yang, G. Li, Z. Shi, S. Feng, Inorg. Chem. 45 (2006) 2474;
(c) S. Wang, Y. Hou, E. Wang, Y. Li, L. Xu, J. Peng, S. Liu, C. Hu, New J. Chem. 27
(2003) 1144.
[6] (a) L.G. Beauvais, M.P. Shores, J.R. Long, J. Am. Chem. Soc. 122 (2000) 2763;
(b) H. Jianghua, Y. Jihong, Z. Yuetao, P. Qinhe, X. Ruren, Inorg. Chem. 44 (2005)
9279.
[7] (a) D. Ghoshal, A.K. Ghosh, G. Mostafa, J. Ribas, N.R. Chaudhuri, Inorg. Chim.
Acta 360 (2007) 1771;
5. Conclusions
Changing the pendant arm length and orientation within aro-
matic dicarboxylates has permitted the synthesis of luminescent
2D and 3D cadmium coordination polymers incorporating the
kinked and hydrogen-bonding donating dpa co-ligand. The
wider-spanning 1,3-phda ligand, with its meta disposition of ace-
tate groups, resulted in a (4,4) grid structure in 2 in which notice-
ably different grid apertures are induced by the conformational
flexibility of the ligand pendant arms. Shortening one of the pen-
dant arms and shifting to an ortho carboxylate disposition in the
hmph ligand did not alter the coordination polymer dimensional-
ity. However, the layer topology was adjusted into a herringbone
pattern in the case of 1. The use of an meta substituted aromatic
dicarboxylate with rigid arms resulted in a 3-D coordination poly-
mer with an uncommon topology in 3. The flexible coordination
geometry at cadmium, because of its lack of crystal field stabiliza-
tion, can adapt to the steric and geometric requirements of both
dicarboxylate and diimine donors in this system. In 1–3, hydro-
gen-bonding donation provided by the central amine of the dpa li-
gand plays a significant auxiliary structure-directing role. Further
(b) C. Livage, C. Egger, M. Nogues, G. Ferey, Compt. Rend. Acad. Sci. Ser. Chem. 4
(2001) 221.
[8] (a) L. Pan, K.M. Adams, H.E. Hernandez, X. Wang, C. Zheng, Y. Hattari, K.
Kaneko, J. Am. Chem. Soc. 125 (2003) 3062;
(b) Y.-F. Zhou, R.-H. Wang, B.-L. Wu, R. Cao, M.-L. Hong, J. Mol. Struct. 697
(2004) 73;
(c) J. Zhou, C. Sun, J. Linpei, J. Mol. Struct. 832 (2007) 55;
(d) Y. Yang, M.-H. Zheng, S.H. Zhang, H. Liang, Acta Crystallogr. E63 (2007)
m2392.
[9] (a) W.-G. Lu, C.-Y. Su, T.-B. Lu, L. Jiang, J.-M. Chen, J. Am. Chem. Soc. 128 (2006)
34;
(b) S. Horike, R. Matsuda, S. Kitagawa, Stud. Surf. Sci. Catal. 156 (2005) 725;
(c) C. Qin, X.-L. Wang, Y.-G. Li, E.-B. Wang, Z.-M. Su, L. Xu, R. Clerac, Dalton
Trans. (2005) 2609;
(d) Y.-Q. Zheng, E.-R. Ying, Polyhedron 24 (2005) 397;
(e) S.K. Ghosh, J. Ribas, P.K. Bharadwaj, Cryst. Growth Des. 5 (2005) 623;
(f) X.-Z. Sun, Y.-F. Sun, B.-H. Ye, X.-M. Chen, Inorg. Chem. Commun. 6 (2003)
1412.