Journal of Molecular Structure 1035 (2013) 183–189
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Two intricate hydrogen-bonded networks formed by m-sulfophenylphosphonic acid, melamine, and water molecules Zi-Yi Du ⇑, Cui-Cui Zhao, Zhong-Gao Zhou, Ke-Jun Wang College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, PR China
h i g h l i g h t s " Cocrystallization of melamine with a trinary acid containing both sulfonic and phosphonic moieties is investigated. " Different molar ratios of the acid–base component lead to two distinct cocrystals. " Two very intricate hydrogen-bonded networks are formed.
a r t i c l e
i n f o
Article history: Received 17 May 2012 Accepted 19 September 2012 Available online 27 September 2012 Keywords: Cocrystal Melamine Sulfonic acid Phosphonic acid Hydrogen-bond network
a b s t r a c t Cocrystallizations of melamine (ma) with m-sulfophenylphosphonic acid (sppH3) from water in different molar ratios (2:1 and 4:1) offer [(maH)2(sppH)]3H2O (1) and [(maH)3(spp)(ma)]12H2O (2), respectively. Structure analysis reveals that two very intricate hydrogen-bonded networks are formed in them, with two or three protons of the m-sulfophenylphosphonic acid being transferred to melamine. The resultant (sppH)2 or (sppH)3 anion can form as many as 12 or 14 hydrogen bonds with melamine and water molecules, showing a very high hydrogen-bonding capability. Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction The understanding of intermolecular interactions in molecular crystals is very significant for the design of novel materials with tailored structures and properties [1]. Specifically, hydrogen bond is one of the most important intermolecular interactions, owing to its directionality and energetic favorability [2]. With this in mind, a large number of crystal structures has been evaluated during the last two decades and a series of frequently recurring hydrogen-bond motifs has been identified. As an excellent hydrogen donor and hydrogen acceptor, melamine, a famous organic base with a 1,3,5-triazine skeleton, has been widely utilized to create one-, two-, and three-dimensional (1D, 2D, and 3D) networks in combination with various carboxylic acids such as glutaric acid, maleic acid, terephthalic acid, benzene1,3,5-tricarboxylic acid, malonic acid, 3,5-dinitrobenzoic acid, Kemp’s triacid, bile acid, dihydroxybenzoic acid, and tris(2-
⇑ Corresponding author. Tel./fax: +86 797 8393670. E-mail address:
[email protected] (Z.-Y. Du). 0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molstruc.2012.09.053
carboxyethyl)isocyanuric acid [3,4]. However, the employment of other organic acid such as sulfonic or phosphonic acid as the counterpart component were rarely investigated [5,6]. Compared with carboxylic acid, sulfonic or phosphonic acid features additional potential hydrogen-bonding sites owing to their third O atoms, which would lead to more complicated hydrogen-bond interactions. This stimulates us to construct supramolecular architectures of melamine and m-sulfophenylphosphonic acid (a trinary acid containing both sulfonic and phosphonic moieties, marked as sppH3), which would be expected to exhibit diversified hydrogen-bonding modes and interesting architectures. So far no cocrystals of sppH3 with organic base have been structurally characterized, although our previously works have shown that (spp)3 anion can be efficiently used to construct metal phosphonate clusters [7]. In addition, the (sppH)2 anion can also be employed as an organic counter-ion for constructing hybrid inorganic–organic supramolecular arrays [8]. Our current research efforts yielded two cocrystals of melamine (ma) with sppH3 in different molar ratios from water solution, namely, [(maH)2 (sppH)]3H2O (1) and [(maH)3(spp)(ma)]12H2O (2). Herein, we report their syntheses and crystal structures.
184
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189
2. Experimental 2.1. Materials and methods m-Phosphonophenylsulfonic acid was synthesized according to the procedures previously described by Montoneri [9]. All other chemicals were obtained from commercial sources and used without further purification. Elemental analyses were performed on a German Elementary Vario EL III instrument. FT-IR spectra were recorded on a Perkin–Elmer Spectrum 2000 FT-IR spectrometer using KBr pellets in the range of 4000–400 cm1. 2.1.1. Synthesis of [(maH)2(sppH)]3H2O (1) Compound 1 was prepared by mixing hot aqueous solutions of melamine and sppH3 at 2:1 M ratio. The hot mixtures were stirred at room temperature and filtered. After a few days, colorless palte-shaped crystals of 1 were deposited from the filtrates, in a ca. 88% yield based on sppH3. Anal. Calcd for C12H25N12O9P1S1 (Mr = 544.47): C 26.47, H 4.63, N 30.87%. Found: C 26.41, H 4.78, N 30.75%. IR data (KBr, cm1): 3363(s), 3147(s), 2694(m), 2449(m), 1622(s), 1560(m), 1514(s), 1406(m), 1334(m), 1223(s), 1157(s), 1113(s), 1036(s), 980(m), 904(m), 796(m), 777(m), 688(m), 622(m), 553(s). 2.1.2. Synthesis of [(maH)3(spp)(ma)]12H2O (2) Compound 2 was prepared in a similar procedure except that the ratio of melamine and sppH3 was increased to 4:1. The resultant crystals are block-shaped. Yield: ca. 81% based on sppH3. Anal. Calcd for C18H55N24O18P1S1 (Mr = 958.89): C 22.55, H 5.78, N 35.06%. Found: C 22.63, H 5.64, N 35.12%. IR data (KBr, cm1): 3329(m), 3136(s), 2682(m), 2366(m), 1686(s), 1660(s), 1629(m), 1554(s), 1471(m), 1437(s), 1221(m), 1165(s), 1066(m), 1037(s), 903(m), 816(m), 777(m), 692(m), 621(m), 555(s). 2.2. Crystal structure determination for compounds 1 and 2 Data collection for compounds 1 and 2 were performed on a Smart ApexII CCD diffractometer equipped with a graphite-monochromated Mo Ka radiation (k = 0.71073 Å). Intensity data for both compounds were collected using u and x scans at 296 K. The data sets were corrected for Lorentz and polarization factors as well as for absorption by SADABS program [10]. Both structures were solved by the direct method and refined by full-matrix leastsquares fitting on F2 by SHELX-97 [11]. All hydrogen atoms except those attached to the O atoms or the ring N atoms were generated geometrically. All non-hydrogen atoms were refined with anisotropic thermal parameters whereas all hydrogen atoms were refined isotropically. The hydrogen atoms for the water molecules in 2 are not included in the refinements. Crystallographic data and structural refinements for 1 and 2 are summarized in Table 1. Important bond lengths and angles for them are listed in Tables 2 and 4, respectively. 3. Results and discussion 3.1. Description of structure 1 Compound 1 crystallizes in the triclinic space group P-1. The asymmetric unit of it contains one 2H-deprotonated (sppH)2 anion, two 1H-protonated (maH)+ cations, and three water molecules (Fig. 1). Judging from the PAO and SAO bond distances of the (sppH)2 anion (Table 2), one sulfonic and one phosphonic protons of sppH3 are transferred to two ring N atoms (N2 and N8) of two melamine molecules. The protonation of each melamine molecule at one of its three ring N atoms is also evidenced by the fact that
Table 1 Summary of crystal data and structural refinements for 1 and 2. Compound
1
2
Empirical formula Formula weight Space group
C12H25N12O9P1S1 544.47 P-1 6.7317(1)
C18H55N24O18P1S1 958.89 P-1 10.1920(4)
0
a (Å A) 0
b (Å A) 0
c (Å A) a (°) b (°) c (°) V (Å3) Z Dcalcd (g cm3) l (mm1) GOF on F2 R1, wR2 [I > 2r(I)] R1, wR2 (all data) R1 =
10.7821(1)
13.9995(7)
17.2484(2)
16.1481(8)
74.935(1) 80.036(1) 74.843(1) 1159.40(2) 2 1.560 0.280 1.038 0.0435, 0.1101 0.0572, 0.1187
77.462(4) 77.848(3) 75.058(3) 2143.70(17) 2 1.486 0.209 0.949 0.0766, 0.2017 0.1646, 0.2434
P P P P ||Fo| |Fc||/ |Fo|, wR2 = { w[(Fo)2 (Fc)2]2/ w[(Fo)2]2}1/2.
Table 2 Selected bond lengths (Å) and angles (°) for 1. P(1)AO(3)
1.4972(16)
P(1)AO(2)
1.5293(16)
P(1)AO(1) S(1)AO(4) C(8)AN(1)AC(7) C(9)AN(3)AC(7) C(12)AN(8)AC(11)
1.5590(16) 1.4461(17) 115.52(16) 115.56(16) 119.66(16)
S(1)AO(6) S(1)AO(5) C(8)AN(2)AC(9) C(11)AN(7)AC(10) C(12)AN(9)AC(10)
1.434(2) 1.4481(18) 119.35(16) 115.67(17) 115.91(16)
the internal CANAC angle involving the protonated ring N atom is significantly greater than the remaining two CANAC angles involving the non-protonated ring N atoms (Table 2), on considering that the lone pair of electrons on the ring N atoms occupies a wider region than the NAH bonding pair. Extensive hydrogen bond interactions can be observed in 1. A close analysis reveals that there are three types of secondary building units (SBUs) in the crystal structure (Fig. 2): cationic [(maH)+]1 ribbon, anionic [(sppH)2]2 dimer and netural water molecules (marked as A, B and C, respectively). SBU A, a onedimensional [(maH)+]1 ribbon running along the b-axis, is formed by pairs of the almost linear NAH N hydrogen bonds (Fig. 2a, Table 3) between two crystallographically independent (maH)+ cations. Such ribbon is frequently observed in cocrystals of melamine [3–6], and it features a N4-involved R22 ð8Þ ring motif, discussed here according to graph-set analysis nomenclature [12]. On the other hand, SBU B, a [(sppH)2]2 dimer related by an inverse center, is formed by a pair of somewhat short but very strong O1AH1A O2 hydrogen bonds in an almost linear geometry (Fig. 2b, Table 3). Thus, a centrosymmetric, O4-involved R22 ð8Þ ring motif can be identified in B. The combination of two adjacent A ribbons through the hydrogen bonds and electrostatic interactions of the charge-balanced B dimers leads to a larger-scale one-dimensional ladder-like chain ‘‘A–B1–A’’ (Fig. 3), generating five new H-bonding patterns (i.e., N2O2-involved R22 ð8Þ, N3O1-involved R23 ð8Þ, N3O2-involved R33 ð9Þ, N1O3-involved R23 ð12Þ, and N4O4-involved R44 ð24Þ rings). Such ‘‘A– B1–A’’ chain possesses inherited inverse centers arising from the centered B dimers. Furthermore, the ladder-like ‘‘A–B1–A’’ chains stack along the ac-plane via inter-chain p p packing interactions between pairs of the neighboring melamine rings, leaving out a centrosymmetric hydrophilic channel running along the b-axis, with SBU C (three crystallographically independent guest water molecules) residing in it (Fig. 4). It is worthy of note that such a channel is surrounded by abundant amino groups and phosphonate/sulfonate groups, which function as H-bond donors and
185
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189
Fig. 1. ORTEP representation of the asymmetry unit of 1. The thermal ellipsoids are drawn at 30% probability.
Table 3 The geometry (Å, °) of hydrogen bonds in 1. d(DAH A)
d(DAH)
d(H A)
d(D A)
Angle
O1WAH1WA O6#1 O1AH1A O2#2 O1WAH1WB O3 N2AH2B O3#3 O2WAH2WA O5 O2WAH2WB O4#4 N4AH4B N9#5 N4AH4C O2W#6 O3WAH3WA O2#3 N5AH5B N7#7 N5AH5C O5 O3WAH3WB O1#1 N6AH6B O4#8 N6AH6C O2#3 N8AH8B O1W#1 N10AH10A N3#5 N10AH10B O5#7 N11AH11A N1#7 N11AH11B O1W#1 N12AH12A O2W#9 N12AH12B O3W
0.86(3) 0.98(3) 0.85(3) 0.88(2) 0.84(3) 0.86(3) 0.86 0.86 0.87(3) 0.86 0.86 0.84(4) 0.86 0.86 0.81(2) 0.86 0.86 0.86 0.86 0.86 0.86
1.86(3) 1.60(3) 1.87(3) 1.79(2) 1.99(3) 1.98(3) 2.15 2.12 2.04(3) 2.15 2.17 2.08(4) 2.01 2.13 1.99(2) 2.22 2.14 2.22 2.14 2.29 1.94
2.706(3) 2.575(2) 2.696(3) 2.656(2) 2.809(3) 2.817(3) 3.001(3) 2.854(3) 2.889(3) 3.005(3) 2.812(3) 2.916(3) 2.814(3) 2.982(2) 2.742(3) 3.073(3) 2.964(3) 3.076(2) 2.883(2) 3.140(4) 2.785(3)
169(3) 178(3) 165(3) 169(2) 167(3) 165(4) 169 143 166(3) 175 131 174(5) 155 169 155(2) 172 161 176 144 171 166
Symmetry codes: #1 1 x, 1 y, 1 z; #2 x, 2 y, 1 z; #3 x, 1 y, 1 z; #4– 1 + x, y, z; #5 1 x, y, z; #6 x, 1 y, z; #7 1 x, 1 y, z; #8 x, 1 + y, z; #9 1 + x, 1 + y, z.
Table 4 Selected bond lengths (Å) and angles (°) for 2.
+
2
Fig. 2. H-bonding modes of the (maH) cations (a), (sppH) anion (b), and water molecules (c) in 1. Hydrogen bond interactions are represented by dashed lines.
acceptors for the guest water molecules, respectively. The guest water molecules here has three different H-bonding patterns (Fig. 2c, Table 3): (1) O1W acts as two H-bond acceptors of one
P(1)AO(2)
1.515(4)
P(1)AO(3)
1.521(4)
P(1)AO(1) S(1)AO(6) C(9)AN(1)AC(7) C(9)AN(3)AC(8) C(10)AN(8)AC(11) C(13)AN(13)AC(15) C(15)AN(15)AC(14) C(16)AN(20)AC(17)
1.531(4) 1.454(4) 118.9(4) 115.7(4) 115.9(4) 118.9(5) 116.0(4) 115.0(4)
S(1)AO(5) S(1)AO(4) C(7)AN(2)AC(8) C(12)AN(7)AC(10) C(12)AN(9)AC(11) C(13)AN(14)AC(14) C(18)AN(19)AC(16) C(18)AN(21)AC(17)
1.448(4) 1.464(5) 115.7(4) 118.6(4) 114.9(4) 115.1(4) 114.3(4) 113.9(4)
amino H atom and one ring-N-attached H atom as well as two H-bond donors of one phosphonate O atom and one sulfonate O atom; (2) O2W serves as a H-bond acceptor of one amino H atom as well as two H-bond donors of two sulfonate O atoms; (3) O3W functions as a H-bond acceptor of one amino H atom as well as two H-bond donors of two phosphonate O atoms. Overall, the self-assembly of the host ‘‘A–B1–A’’ and guest C components results in an intricate hydrogen-bonded network,
186
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189
Fig. 3. One-dimensional ladder-like chain formed by hydrogen bond interactions between the (sppH)2 and (maH)+ ions in 1. For display details, see Fig. 2.
Fig. 4. View of the supermolecular structure of 1 down the b axis. Hydrogen atoms have been omitted for clarity. H-bonding and p p interactions are represented by black and gold dashed lines, respectively. For other display details, see Fig. 2.
which is further stablized by p p stacking interactions between the aromatic rings of the melamines. 3.2. Description of structure 2 Compound 2 also crystallizes in the triclinic space group P-1. The asymmetric unit of it contains one 3H-deprotonated (spp)3 anion, three 1H-protonated (maH)+ cations, one netural melamine molecule, and as many as twelve water molecules (Fig. 5). Judging from the PAO and SAO bond distances of the (spp)3 anion (Table 4), one sulfonic and two phosphonic protons of sppH3 are transferred to three ring N atoms (N1, N7 and N13) of three melamine molecules, which is different to that in 1. The 1H-protonation of three melamine molecules in 2 is also evidenced by the fact that
the internal CANAC angle involving the protonated ring N atom is significantly greater than the remaining two CANAC angles involving the non-protonated ring N atoms (Table 4). Compared with 1, more complicated hydrogen bond interactions can be observed in 2, although the location of all hydrogen atoms of the water molecules could not be accurately evaluated because of the somewhat poor crystal data of 2. The SBUs in the crystal structure of 2 also can be classified as three categories: cationic {[(maH)3(ma)]3+}1 ribbon, anionic (spp)3 monomer and twelve netural water molecules (marked as A0 , B0 and C0 , respectively). SBU A0 , a one-dimensional {[(ma)(maH)3]3+}1 ribbon running along the a-axis, is formed by pairs of the almost linear NAH N hydrogen bonds (Fig. 6a, Table 5) among one netural and three 1H-protonated melamine molecules, which is similar
187
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189 Table 5 The geometry (Å, °) of hydrogen bonds in 2.
Fig. 5. ORTEP representation of the asymmetry unit of 2. The thermal ellipsoids are drawn at 30% probability. Hydrogen atoms have been omitted for clarity.
Fig. 6. (a) One-dimensional melamine chain along the a axis, formed by hydrogen bond interactions of the melamines in 2. (b) One-dimensional melamine chain along the b axis, formed by p p interactions of the melamines in 2. For display details, see Fig. 2.
to the A SBU in 1. On the other hand, different to the B SBU in 1, the B0 SBU in 2 is an anionic (spp)3 monomer and acts as a highcapacity H-bond acceptor becauce of its six H-free O atoms. The combination of the A0 ribbons via the hydrogen bonds and electrostatic interactions of the charge-balanced B0 monomers generates a complicated two-dimensional \—A02 —B1 —A02 —B1 —" double-layer, in which the phosphonate and sulfonate moieties of the B0 monomers are H-bonded with one and two A0 ribbons, respectively (Fig. 7). Such double-layer possesses inverse centers located between two adjacent (spp)3 monomers along the a-axis. Furthermore, these double-layers stack along the b-axis via intra- and inter-layer p p packing interactions between pairs of the neighboring melamine rings (Fig. 6b), of which two adjacent double-layers are also related by inverse centers. Similarly to the stacking of the ladder-like ‘‘A–B1–A’’ chains in 1, the stacking of the double-layers in 2 also leaves out a centrosymmetric hydrophilic channel running along the b-axis, but with more guest water molecules (SBU C0 ) residing in it (Fig. 8).
d(DAH A)
d(DAH)
d(H A)
d(D A)
Angle
N(1)AH(1A) O(1)#1 N(4)AH(4B) N(8)#2 N(4)AH(4C) O(2)#1 N(5)AH(5B) O(3W)#3 N(5)AH(5C) N(21)#4 N(6)AH(6B) O(4W) N(6)AH(6C) O(7W)#1 N(7)AH(7A) O(2W) N(10)AH(10A) N(2)#2 N(10)AH(10B) O(2W) N(10)AH(10B) O(3W)#1 N(11)AH(11A) O(5W)#3 N(11)AH(11B) N(15)#5 N(12)AH(12A) O(5) N(12)AH(12B) O(9W) N(13)AH(13A) O(8W) N(16)AH(16A) N(20)#5 N(16)AH(16B) O(4)#6 N(17)AH(17A) O(6)#5 N(17)AH(17B) N(9)#5 N(18)AH(18A) O(5W)#7 N(18)AH(18B) O(11W) N(22)AH(22A) N(14)#5 N(22)AH(22B) O(6) N(23)AH(23B) N(3)#4 N(24)AH(24A) O(3W)#8 N(24)AH(24B) O(12W) O(1W)AH N(19)#7 O(1W)AH O(1) O(1W)AH O(10W) O(2W)AH O(3)#1 O(3W)AH O(2) O(3W)AH O(4W)#9 O(4W)AH O(4) O(4W)AH O(6W) O(5W)AH O(2) O(5W)AH O(6)#7 O(6W)AH O(3) O(6W)AH O(3)#9 O(6W)AH O(9W)#2 O(7W)AH O(1) O(7W)AH O(9W) O(8W)AH O(11W) O(10W)AH O(11W) O(10W)AH O(11W)#10 O(10W)AH O(12W)#7 O(12W)AH O(2)#8
0.86(6) 0.86 0.86 0.86 0.86 0.86 0.86 0.91(5) 0.86 0.86 0.86 0.86 0.86 0.86 0.86 0.84(6) 0.86 0.86 0.86 0.86 0.86 0.86 0.86 0.86 0.86 0.86 0.86
1.82(6) 2.19 2.24 2.13 2.06 2.09 2.18 1.86(5) 2.13 2.52 2.49 2.11 2.10 2.03 2.14 2.04(6) 2.07 2.27 2.26 2.42 2.18 2.13 2.17 2.39 2.47 2.37 2.34
2.676(6) 3.043(6) 3.070(6) 2.938(6) 2.907(6) 2.914(6) 3.026(8) 2.739(7) 2.990(6) 3.203(7) 3.135(6) 2.873(6) 2.948(6) 2.835(6) 2.982(10) 2.833(8) 2.923(6) 2.974(7) 3.101(6) 3.279(6) 3.019(6) 2.941(9) 3.025(6) 3.043(6) 3.325(6) 3.180(6) 2.981(9) 2.742 2.756 2.722 2.723 2.735 2.907 2.820 2.771 2.712 2.872 2.746 2.746 3.086 2.720 2.841 2.994 2.657 3.006 2.600 3.058
176(6) 175 161 157 168 160 166 161(5) 173 137 133 147 168 155 165 158(5) 174 140 167 176 165 158 177 133 175 158 132
Because all hydrogen atoms of the water molecules were not localized, the hydrogen bonds marked with were determined from donor–acceptor distances. Symmetry codes: #1 1 x, y, 1 z; #2 2 x, y, z; #3 1 + x, y, 1 + z; #4 x, 1 y, z; #5 1 x, 1 y, z; #6 1 + x, y, z; #7 x, 1 y, 1 z; #8–1 x, 1 y, 1 z; #9 x, y, 1 z; #10 1 x, 1 y, 1 z.
Overall, the self-assembly of the host \—A02 —B1 —A02 —B1 —" and guest C0 components results in an intricate hydrogen-bonded network, which is further stablized by p p stacking interactions between the aromatic rings of the melamines. 4. Conclusion In summary, two very intricate hydrogen-bonded networks are observed in 1 and 2. The hydrogen bonds and electrostatic interactions of the partly or fully deprotonated m-sulfophenylphosphonic acid with the protonated and/or neutural melamine in 1 and 2 generate a one-dimensional ladder-like chain of [(maH)2(sppH)] and a two-dimensional double-layer of [(maH)3(spp)(ma)], respectively, depending on the initial (ma):(sppH3) molar ratios. Furthermore, the p p stacking interactions between the melamine rings contribute to their overall three-dimensional packings, which also leave out hydrophilic channels with guest water molecules
188
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189
Fig. 7. Two-dimensional double-layer formed by hydrogen bond interactions among the melamine molecules, (spp)3 and (maH)+ ions in 2. For display details, see Fig. 2.
Fig. 8. View of the supermolecular structure of 2 down the b axis. The CPO3 and CSO3 groups are shaded in purple and yellow, respectively. Hydrogen atoms have been omitted for clarity. H-bonding interactions are represented by dashed lines. For other display details, see Fig. 2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).
residing in them. The (sppH)2 and (spp)3 anions in them can form as many as 12 or 14 hydrogen bonds with melamine and water molecules (Tables 3 and 5), showing a very high hydrogenbonding capability.
data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.molstruc.2012.09.053.
References Acknowledgments This work was supported by the NNSF of China (No. 21061001), the NSF of Jiangxi Province (No. 20114BAB203004) and the NSF of Jiangxi Provincial Education Department (No. GJJ10714).
Appendix A. Supplementary material CCDC Reference Numbers 881234 and 881235 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary
[1] (a) K.R. Seddon, M.J. Zaworotko, Crystal Engineering: The Design and Application of Functional Solids, Kluwer Academic, Dordrecht, 1999; (b) G.R. Desiraju, J. Mol. Struct. 656 (2003) 5; (c) D. Braga, L. Brammer, N.R. Champness, CrystEngComm 7 (2005) 1; (d) G.R. Desiraju, Angew. Chem., Int. Ed. 46 (2007) 8342. [2] (a) B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629; (b) K. Biradha, CrystEngComm 5 (2003) 374; (c) L.S. Reddy, S. Basavoju, V.R. Vangala, A. Nangia, Cryst. Growth Des. 6 (2006) 161. [3] (a) J. Janczak, G.J. Perpétuo, Acta Crystallogr., Sect. C 58 (2002) o339; (b) J. Janczak, G.J. Perpétuo, Acta Crystallogr., Sect. C 60 (2004) o211; (c) X.-L. Zhang, X.-M. Chen, Cryst. Growth Des. 5 (2005) 617; (d) S. Eppel, J. Bernstein, Cryst. Growth Des. 9 (2009) 1683; (e) A. Huczynski, J. Janczak, B. Brzezinski, J. Mol. Struct. 922 (2009) 77. [4] (a) S. Ikonen, Nonappa, E. Kolehmainen, CrystEngComm 12 (2010) 4304; (b) S. SeethaLekshmi, T.N. Guru Row, CrystEngComm 13 (2011) 4886; (c) F. Dai, D. Sun, W. Sun, Y.-Q. Liu, D. Sun, CrystEngComm 14 (2012) 1376.
Z.-Y. Du et al. / Journal of Molecular Structure 1035 (2013) 183–189 [5] (a) J. Janczak, G.J. Perpetuo, Acta Crystallogr., Sect. C 57 (2001) 873; (b) X.-L. Zhang, B.-H. Ye, X.-M. Chen, Cryst. Growth Des. 5 (2005) 1609. [6] (a) M. Plabst, N. Stock, T. Bein, Cryst. Growth Des. 9 (2009) 5049. [7] (a) Z.-Y. Du, H.-B. Xu, J.-G. Mao, Inorg. Chem. 45 (2006) 6424; (b) Z.-Y. Du, H.-B. Xu, J.-G. Mao, Inorg. Chem. 45 (2006) 9780; (c) Z.-Y. Du, X.-L. Li, Q.-Y. Liu, J.-G. Mao, Cryst. Growth Des. 7 (2007) 1501; (d) Z.-Y. Du, A. Prosvirin, J.-G. Mao, Inorg. Chem. 46 (2007) 9884; (e) Z.-Y. Du, H.-B. Xu, X.-L. Li, J.-G. Mao, Eur. J. Inorg. Chem. (2007) 4520. [8] Z.-Y. Du, Q.-Y. Liu, H.-R. Wen, Y.-R. Xie, J.-J. Huang, Acta Crystallogr., Sect. C 64 (2008) m353.
189
[9] (a) E. Montoneri, Phosphorus, Sulfur Silicon Relat. Elem. 55 (1991) 201; (b) E. Montoneri, M.C. Gallazzi, Dalton Trans. (1989) 1819. [10] APEX2, SADABS and SAINT, Bruker AXS Inc., Madison, Wisconsin, USA, 2008. [11] (a) G.M. Sheldrick, SHELXS-97, Program for X-ray Crystal Structure Solution, University of Göttingen, Germany, 1997; (b) G.M. Sheldrick, SHELXL-97, Program for X-ray Crystal Structure Refinement, University of Göttingen, Germany, 1997. [12] J. Bernstein, R.E. Davis, L. Shimoni, N.-L. Chang, Angew. Chem., Int. Ed. 34 (1995) 1555.