Exploration of Salts and Cocrystals of 2,2â²,6,6 - ACS Publications

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Exploration of Salts and Cocrystals of 2,2′,6,6′-Tetracarboxybiphenyl with Acetic Acid, Monobasic and Dibasic N‑Heterocycles, and N‑Oxides Sandipan Roy and Kumar Biradha* Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India S Supporting Information *

ABSTRACT: Several complexes of 2,2′,6,6′-tetracarboxybiphenyl (H41) with various N-containing heterocycles and N-oxides were synthesized and their crystal structures were analyzed in terms of salt/cocrystal, deprotonation, synthons, and network geometries. The tetra carboxylic acid, H41, was found to act as a host for the inclusion of acetic acid dimers. For complexation reactions with bases, the mono basic compounds such as pyridine, quinoline, and acridine; the dibasic compounds such as 9,10-phenanthrolene, 4,4′-bipyridylethane, 4,4′-bipyridyldisulfide, phenazine, and 1,4-diazabicyclooctane (dabco); and N-oxides of 4,4′-bipyridine and dabco are considered. In the crystal structures of these complexes, the H41 was found to exist as H21 (double deprotonation of H41), H31 (mono deprotonation of H41), or H41 (cocrystals) forms depending on the basicity of the complexing agent and other factors. Out of 13 complexes studied here the more probable acid-pyridine synthon was observed in one complex, the COO−···HOOC− synthon was found to be dominant as it was observed in seven complexes. The assembling of anions and cations produced versatile network architectures including discrete, onedimensional, two-dimensional, and three-dimensional networks in terms of strong and conventional hydrogen bonds. In some cases, the cations acted as pillars to assemble the layers of anions into three-dimensional networks containing huge channels that are filled by self-interpenetration. Only phenazine was found to form a neutral complex, cocrystal, with H41 among all of the bases used. The weak bases such as N-oxides of 4,4′-bipyridine and dabco were found to be doubly protonated and form polar hydrogen bonded networks.

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often attributed to ΔpKa value, which is defined as pKa(PyNH+) − pKa(COOH). Synthon II forms preferably when the ΔpKa < 0; synthon III forms when 0 < ΔpKa < 3.75, and synthon IV forms when ΔpKa > 3.75. In the pharmaceutical industry ΔpKa > 3 is used as a rule of thumb for selecting counterions to prepare salt forms. However, in practice the pKa values of acids and pyridines vary based on the solvents and other accompanying components in the reaction.6 Therefore, it is not easy to predict the nature of the resultant synthons. In the case of acid−pyridine complexes, the possibility of observing synthon-III/IV is higher when the anions do not have any other choices of self-assembling. On the other hand, in the case of poly carboxylic acids, some remain as −COOH and some become deprotonated by pyridine to yield −COO−. As a result the −COOH···−OOC synthon becomes a greater possibility over synthons III and IV. Further, acid-pyridine synthons were effectively utilized to transfer the molecular symmetry into the network symmetry. In number of cases, the 3-fold symmetric tricaboxylic acid was shown to form honeycomb networks via acid-pyridine synthon when treated with a connecter such as 4,4′-bipyridne and other

INTRODUCTION Crystal engineering of materials based on two chemical components is of importance due to their modular nature, predictability, and functional properties.1 In this process, the functional groups, capable of forming hydrogen bonds, present on the components play a significant role in driving the assembly process.2 Among all possible supramolecular synthons that can be used for the two component design,3 the homosynthon between carboxylic acids (I), and hetero synthon between carboxylic acid and pyridine functinalities4 (II−IV; Scheme 1) were well explored Scheme 1

given their commonality in the organic compounds and applicability in the pharmaceutical industries for synthesizing drug cocrystals or salts.5 Recent studies using Cambridge Structural Database (CSD) reveal that the acid-pyridine synthon has a high probability of formation among all of the possible hetero or homo synthons. These synthons are of three types: neutral, mixed ionic, and ionic. The occurrence of synthons II−IV was © 2013 American Chemical Society

Received: April 30, 2013 Revised: June 1, 2013 Published: June 3, 2013 3232

dx.doi.org/10.1021/cg400661d | Cryst. Growth Des. 2013, 13, 3232−3241

Crystal Growth & Design

Article

relevant linear linkers.4a,i,7 For example, we have recently shown that 1,3,5-benzene tricarboxylic acid forms a salt when treated with a linear linker containing pyridine moieties.8 In the salt the anions self-assemble to form layers which are pillared by the pyridinium cations. The same reaction when carried out in the presence of phenol results in a cocrystal which contains a triply interpenetrated honeycomb architecture. The phenol promotes the formation of cocrystal by effectively solvating the pyridine moieties. These results exemplified the importance of reaction conditions in obtaining the predefined networks. On the other hand, there are only two examples to date in which the tetrahedral symmetry of molecules transferred into a diamondoid network using acid-pyridine synthon.9 One of the two examples was reported by us using H41 (2,2′,6,6′tetracarboxybiphenyl) and 4,4′-bipyridylethylene (bpe).9b The reaction outcome of these two components was shown to depend upon the concentration of the solution: a cocrystal exhibiting diamondoid architecture was obtained from the concentrated MeOH solution of the components, whereas a salt containing anions self-assembly was obtained from dilute solution of MeOH. It is interesting to note here that H41 itself does not form a diamondoid network via −COOH synthons despite the presence of S4 symmetry in molecules, it forms a layer structure. We have recently shown the utility of H41 and 4,4′bipyridyl ethylene (bpe) or 4,4′-bipyridine (bpy) for the synthesis of ionic complexes (salts) which serve as colorimetric indicators to recognize aromatics via cation−π interactions.10 Further, the acid-pyridine containing salts were recently shown by us and others as good semiconducting materials.11 In this report, we investigate the guest inclusion ability of H41 and reactions of H41 with three types of substrates: monobasic and dibasic N-containing heterocycles and N-oxides. The monobasic compounds are pyridine (py), quinoline (qun), and acridine (acr); dibasic compounds are 9,10-phenanthrolene (phan), 4,4′-bipyridylethane (bpye), 4,4′-bipyridyl disulfide (bpys), phenazine (phen), and 1,4-diazabicyclooctane (dab); and N-oxides of 4,4′-bipyrdine (bpn) and dabco (dabn). The N-oxides are considered to study their deprotonating ability of −COOH groups, in general, and complexation ability with H41 in particular. Although N-oxides are very weak bases, recently it was shown that bpn can exhibit mono or biprotonated forms in the metal complexes and also in its complex with HCl.12 Accordingly, in this manuscript we address the complexation

ability of H41 with the above-described compounds and explore their crystal structures in terms salt/cocrystal, supramoleuclar synthons, and hydrogen bonding networks. These complexes are also characterized by XRPD, DRS, TGA, IR, and elemental analysis.

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RESULTS AND DISCUSSION The molecule H41 was shown earlier by Holeý et al. to form twodimensional grid structure via −COOH dimer synthons.13 Although the 2D-layer contains cavities of dimension 11.8 × 12.1 Å2, the cavities are filled by adjacent layers. Recently we have shown that the pyromellitic acid also forms similar grid structure and incorporates small aromatic guest molecules.14 Therefore, we have explored guest encapsulation ability of H41 in the presence of several aromatic guest molecules without success. However, we are successful in obtaining single crystals of [H41][CH3COOH]2, (2) from MeOH−CH3COOH solution. The single crystals of the complexes 3−9 and 13−15 are obtained by reacting 1 equiv. of H41 (10 mg) with two equiv. of respective basic components in MeOH (8 mL). Further, the reactions were carried out under different concentrations and also by taking H41 and diabasic compounds in 1:1 ratio. In such reactions of H41 with dab, bpye, and bpys in the concentrated solutions of MeOH (2 mL instead of 8 mL) resulted in complexes with different stoichiometries (10−12). These reactions indicated that the concentration of the components in the solution influences the reaction outcome rather than the ratios of the components. The single crystals suitable for X-ray diffraction studies were obtained for the following complexes: [H21][Hdab]2·2H2O, 7 [H31][Hpy]·H2O, 3 [H31][Hbpye]·H2O, 8 [H21][Hqun]2, 4 [H21] [Hbpys]2, 9 [H31]2[H2dab], 10 [H21][Hacr]2, 5 [H31][Hphan]·MeOH, 6 [H31]2[H2bpye], 11

[H41][CH3COOH]2, 2

[H31]2[H2bpys]·2H2O, 12 [H41][phen]2·2H2O, 13 [H21]2[H2bpn]2, 14 [H21][H2dabn], 15

The crystallographic parameters for all of the complexes 2−15 were given in Tables 1 and 2 and hydrogen-bonding parameters of compounds were listed in Tables 3 and 4. In the crystal structures of these complexes, the tetra acid (H41) was found to exist as H21 (double deprotonation of H41), H31 (mono deprotonation of H41) or H41 (cocrystals) forms.

Table 1. Crystallographic Parameters for the Crystal Structures of 2−8 compound

2

3

4

5

6

7

8

formula m. wt. T (K) system space group a (Å) b (Å) c (Å) α (°) β (°) γ (°) vol. (Å3) Z Dcalc (mg/m3) R1 (I > 2σ(I)) wR2 (on F2, all data)

C20H18O12 450.34 293(2) orthorhombic Pbcn 12.0559(11) 12.1955(11) 14.2776(13) 90.00 90.00 90.00 2099.2(3) 4 1.425 0.0711 0.2497

C21H17NO9 427.36 293(2) triclinic P1̅ 8.1122(4) 11.1499(5) 12.1660(5) 66.7980(10) 83.6510(10) 74.3070(10) 973.71(8) 2 1.458 0.0464 0.1313

C34H24N2O8 588.55 293(2) monoclinic C2/c 11.3125(17) 11.7331(17) 20.887(3) 90.00 90.959(5) 90.00 2771.9(7) 4 1.410 0.0679 0.1411


C31H22N2O9 566.51 293(2) orthorhombic Pbca 8.18(2) 24.47(6) 25.99(8) 90.00 90.00 90.00 5202(26) 8 1.447 0.0883 0.1719

C28H38N4O10 590.62 293(2) monoclinic P21 10.7264(8) 12.0799(9) 10.8773(9) 90.00 95.9b49(2) 90.00 1401.82(19) 2 1.399 0.0457 0.1265

C28H24N2O9 532.49 293(2) monoclinic P21/c 13.3500(13) 11.5279(11) 17.3890(17) 90.00 95.474(3) 90.00 2663.9(4) 4 1.328 0.0605 0.1727

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Table 2. Crystallographic Parameters for the Crystal Structures of 9−15 compound

9

10

11

12

13

14

15

formula m. wt. T (K) system space group a (Å) b (Å) c (Å) α (°) β (°) γ (°) vol. (Å3) Z Dcalc (mg/m3) R1 (I > 2σ(I)) wR2 (on F2, all data)

C36H26N4O8S4 770.85 293(2) monoclinic P21/c 15.335(3) 29.750(6) 7.7905(15) 90.00 99.891(6) 90.00 3501.3(11) 4 1.462 0.0788 0.1988

C38H32N2O16 772.66 293(2) monoclinic P21/n 8.2942(17) 15.468(3) 14.615(3) 90.00 102.845(7) 90.00 1828.18 2 1.404 0.0599 0.1687

C44H32N2O16 844.72 293(2) triclinic P1̅ 7.846(4) 10.808(5) 12.352(6) 64.333(13) 83.011(15) 79.355(14) 926.7(8) 1 1.514 0.0700 0.1479

C42H32N2O18S2 916.82 293(2) triclinic P1̅ 12.235(3) 12.600(3) 15.087(3) 105.380(7) 92.414(7) 114.958(6) 2001.3(8) 2 1.521 0.0947 0.2480


C26H18N2O10 518.42 293(2) monoclinic P21/c 31.797(9) 7.950(2) 18.717(6) 90.00 102.685(10) 90.00 4616(2) 8 1.492 0.0989 0.1955


were found to form H31 as well as H21 anions depending on the concentration of the solution. It is interesting to note here that the weak bases such as bpn and dabn are also doubly deprotonating the H41. Only phenazine found to form neutral complex with H41 among all the bases used. The removal or not removal protons in all these structures were confirmed by analyzing corresponding C−O bond distances of −COO−/−COOH groups and also by locating the protons on bases and acids wherever is possible. The difference (d) between the two C−O distances of −COO− and −COOH showed a clear distinction between the both forms (Figure 1). The d values for −COOH groups found to be populated between 0.077 and 0.145 whereas for −COO− the distribution varies from 0.002 to 0.052. Inclusion of CH3COOH Dimers in the (4,4)-Network of H41. The asymmetric unit of 2 is constituted by half unit of H41 and one unit of CH3COOH. The H41 units join each other through −COOH dimer synthons to form a two-dimensional layer similar to the one observed in the crystal structure of H41 itself (Figure 2a).13 In both cases the layers pack along c-axis, however the packing differs significantly. In the crystal structure of H41, the cavities of layer are filled by the adjacent layers, offset packing. (Figure 2c). Whereas in 2, as the cavities are filled by the CH3COOH dimers the layers pack such that they exactly overlap on each other (Figure 2a,b). Accordingly, the interlayer separation is higher in 2 (7.139 Å, 1/2 of the c axis) compared to that of in H41 (5.25 Å, 1/4th of the c axis). The CSD analysis shows that the database contains total of 33 structures in which CH3COOH was incorporated in the crystal lattice. However, the inclusion of acetic acid dimers (synthon-I) in the cavities or channels were observed in only four cases indicating that the example presented here belong to one of the rarest example.15 In other words, one carboxylic acid (H41) is acting as host to include another carboxylic acid (CH3COOH). As for as we know and also based on CSD studies, there is only one such example in which the trimesic acid acts as a host to include dimer of acetic acid.15c Ionic Complexes of H41 with Monobasic Ligands. The complexes 4 and 5 are somewhat iso-structural as both crystallize in C2/c space group and form 0D-structures via charge assisted N−H···O hydrogen bond (Figure 3a). The asymmetric units are constituted by half unit of H21 and one unit of cation. In both cases the H21 anion exhibits two intramolecular O−H···O

Table 3. Hydrogen Bonding Parameters in the Crystal Structures of 2−8 complexes

interaction

H···A (Å)

D···A (Å)

D−H···A (deg)

2

O−H···O

1.84(3) 2.00(3) 2.37 2.34 1.62(2) 1.71(2) 1.85(3) 1.62(2) 1.67(2) 1.15(2) 2.36 1.75(4) 1.53(4) 1.68(3) 1.42(3) 1.67(7) 2.26(8) 1.88(7) 1.45(7) 2.60 1.84 2.01 1.96(3) 2.20(3) 1.84(3) 1.15(3) 2.44 2.06(3) 1.78(3) 1.45(3) 1.81(3) 2.28(4) 1.60(3) 2.43

2.666(2) 2.637(3) 2.699(3) 2.680(3) 2.636(4) 2.744(2) 2.762(3) 2.607(2) 2.650(2) 2.468(2) 2.696(3) 2.679(4) 2.519(4) 2.673(3) 2.488(3) 2.699(13) 2.836(12) 2.760(11) 2.485(10) 3.100(15) 2.693(3) 2.776(3) 2.981(4) 2.947(4) 2.502(3) 2.436(3) 3.373(9) 2.771(4) 2.548(4) 2.534(3) 2.750(4) 2.964(3) 2.528(3) 3.126(4)

164(2) 169(4) 101 101 163(2) 169(2) 177(2) 172(2) 169.6(19) 175(2) 101 164(3) 177(3) 175(2) 176.6(17) 163(5) 140(8) 161(7) 169(5) 115 165 174 162(3) 163(3) 161(6) 169(3) 162 168(3) 172(3) 170(2) 167(2) 130(4) 175(3) 132

C−H···Oa 3

4 5 6

7

8

N−H···O O−H···O

O−H···Oa C−H···Oa N−H···O O−H···Oa N−H···O O−H···Oa N−H···O O−H···O O−H···Oa C−H···O N−H···O N−H···N O−H···N O−H···O O−H···Oa C−H···O O−H···O

O−H···N N−H···O O−H···Oa C−H···O a

Intramolecular.

The bases py, phan, and bpye were found to be good enough to remove only one proton from H41, while the bases qun, acr, bpn, and dabn remove two protons from H41. The bases dab and bpys 3234



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Table 4. Hydrogen Bonding Parameters in the Crystal Structures of 9−15 complexes 9

interaction N−H···O O−H···Oa O−H···N C−H···Oa

10

N−H···O O−H···O

11

12

13

O−H···Oa C−H···O N−H···O O−H···O O−H···Oa O43···O44 O11···O24 O13···O22 O13···N1B O21···N1B C−H···O C−H···O O−H···N O−H···O

14

15

C−H···O C−H···Oa O(12)···O(11A) O(13)···O(11B) O(21)···O(11A) O(22)···O(11A) C−H···O C−H···O C−H···O O−H···O O−H···N C−H···O C−H···Oa

a

H···A (Å)

D···A (Å)

1.96 1.83(5) 1.61(5) 1.68(4) 2.63 2.77 2.58 1.60 1.96 1.61 1.14 2.56 1.92(5) 1.83(5) 1.85(5) 1.09(4)

2.792(8) 2.615(5) 2.585(4) 2.650(4) 3.159(6) 3.229(5) 3.3073 2.6767 2.6590 2.6773 2.5421 3.3828 2.784(6) 2.718(5) 2.615(5) 2.506(5) 2.608(6) 2.542(7) 2.643(6) 3.162(8) 2.768(7) 3.284(9) 3.133(10) 2.767(2) 2.793(3) 2.821(3) 2.575(2) 3.382(3) 2.710(3) 2.655(8) 3.038(14) 3.095(11) 2.584(9) 3.158(10) 3.223(9) 2.989(11) 2.431(4) 2.643(4) 3.162(4) 3.079(6) 2.721(4)

2.37 2.30 1.89(2) 1.99(2) 2.08(2) 1.70(2) 2.52 2.37

2.54 2.31 2.19 1.33(3) 1.74(4) 2.23(3) 2.50 2.40

D−H···A (deg) 162 157(4) 169(4) 177(4) 117 111 124 177 157 169 178 148 156(4) 164(4) 148(5) 176(2)

Figure 1. Histogram of difference values (d) of C−O bond distances of −COO−/−COOH groups in the crystal structures of 2−15.

168 149 165.0(19) 175(2) 174(2) 173.1(19) 154 101

124 168 143 167(2) 160(3) 138.8(18) 118 100

Figure 2. Illustrations for the crystal structure of 2: (a) two-dimensional layer via synthon-I, and notice the inclusion of acetic acid dimers in the square cavities; space filling representation of the stacking of 2D layers in the crystal structures of (b) 2 and (c) H41 in which the cavities are filled by adjacent layers due to offset packing.

Intramolecular.

hydrogen bonds between adjacent −COOH and COO− groups. The 0D-aggregates further link into one-dimensional chains via C−H···O hydrogen bonds such that there exist cation···π and π···π interactions between the Hqun/Hacr units (Figure 3b). These one-dimensional chains are further assembled into twodimensional network via C−H···O and π···π interactions (Figure 3b). The distances between the bridged antiparallel Hqun or Hacr units are 3.56 or 3.78 Å, respectively. Similar type of association of antiparallel Hacri stacking was observed in the terephthalic acid complex of acridine.4h Further, these two structures also have similar features to those of pyromellate with bases pyridinium and quinolinium.16 The asymmetric unit of complexes 3 and 6 contain one unit each of H31 and cation, in addition they also contain one water and MeOH respectively. In the crystal structure of 3, the H31 moiety contains only one intramoleuclar hydrogen bond and

assembles into a one-dimensional chain via COO−···HOOC− interactions (Figure 4a). These one-dimensional chains further assembled into two-dimensional layer, by H2O molecules, containing rectangular cavities which are filled by adjacent layers (Figure 4a). The pyridinium ions hang above and below the layer by hydrogen bonding to H2O molecule but not to the carboxylates (Figure 4b). In the crystal structure of 6, unlike in 3, the anions self-assemble via COO−···HOOC interactions to form a two-dimensional layer (Figure 4c). The H31 moieties similar to 3 contain one intramolecular hydrogen bond. The MeOH clings above and below the layer via hydrogen bonding MeOH···−OOC to twodimensional layer which further hydrogen bonds to cations (MeO(H)···H−N+− (Figure 4d). It is interesting to note here, 3235



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to form a dimer via N+-H···N hydrogen bonds, therefore one of this dimer contains neutral N-atom and the other end contains N+−H. The protonated end of this dimer hydrogen bonds to −COO− (−N+−H···N−) of the above-mentioned 1D-chain while the neutral end hydrogen bonds to H2O (HOH···N) and thus the 1D chains assemble into 2D network (Figure 5a). The complexes 8 and 9 contain bispyridyl groups with spacers −CH2−CH2- (bpye) and S−S (bpys) respectively. The bpye unit is known to exhibit several conformers while bpys known to exhibit only angular conformation. The reaction of 1:2 equivalent of H41 with bpye and bpys resulted in different products. The bpye removes only one proton from H41 to form complex 8, whereas similar reaction with bpys resulted in double deprotonation of H41 to form complex 9. Similar to complex 7, two units of bpys were used to deprotonate H41 to H21. In the complex 8, the H31 units (one intermolecular) form dimers which are further linked by H2O molecules to form twodimensional herringbone layer containing rectangular cavities (Figure 6a). Hbpye units join these layers as neutral end hydrogen bonds to H2O (N···HOH) and charged end hydrogen bonds to carboxylate (N+−H····−OOC) to result in 3-dimensional network (Figure 6b). Two of such 3D-networks interpenetrated in the crystal lattice via aromatic interactions between pyridyl units and biphenyl units of H31 (Figure 6c). In case of 9, one of the two protons of H21 involves in intramolecular hydrogen bond with COO− while the other forms intermolecular hydrogen bond with neutral N-atom of Hbpys. As a result one of the Hbpys joins the H21 units into a onedimensional chain via synthon-II and synthon-IV while the other Hbpys hangs both sides of the chain via N+−H···−OOC hydrogen bonds (Figure 7a). These chains are further interconnected via weak C−H···O hydrogen bonds, aromatic π···π and N···S (3.498 Å) interactions to form a 2D-network (Figure 7b). Interestingly, repeat of these three reactions of H41 with dibasic compounds in the concentrated solutions resulted in the

Figure 3. Illustrations for the crystal structures of 4 and 5: Discrete aggregate via charge assisted N−H···O hydrogen bonds in (a) 4 and (b) 5; (c) two-dimensional layers of discrete aggregates via C−H···O and π···π interactions.

in both cases 3 and 6, the cations do not hydrogen bond to anions but to the solvents. Ionic Complexes of H41 with Dibasic Ligands Containing Exodentate Geometry. In complex 7, dab as a strong base, similar to quinoline (qun) and acridine (acr), doubly deprotonates H41 to yield H21 which contains two intramolecular hydrogen bonds. It is noteworthy here that two units of dab are required to convert H41 to H21. The asymmetric unit is constituted by one unit of H21 and two units each of Hdab and H2O. Water molecules play a crucial role in assembling the anions and cations, one of the two water molecules link the anions into one-dimensional chain while the other links cations to this one-dimensional chain (Figure 5a). The cations assemble

Figure 4. Illustrations for the crystal structures of 3 and 6: (a) Assembling of one-dimensional chains into 2D-layers via water molecules in 3; (b) hanging of the pyridinium ions on both sides of the layer (side view) in 3 (c) assembling of anions (H31) to form corrugated layer in 6; (d) hanging of MeOH and phenathorlinium ions on bothe side of the layers (side view) via MeO(H)···H−N+− in the crystal structure of 6. 3236



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Figure 5. Illustrations for the crystal structures of 7: Two-dimensional layers via assembling of anions (H21), cations and water molecules (a) top view and (b) side view.

Figure 6. Illustrations for the crystal structures of 8: (a) assembling of anions (H31) to form two-dimensional herringbone layer by H2O molecules; (b) three-dimensional network via joining of anionic layers by Hbpye cations via charge assisted N−H···O hydrogen bonds; (c) 2-fold interpenetration of 3D networks.

Figure 7. Illustrations for the crystal structures of 9: (a) onedimensional chain of anions (H21) and cations Hbpys via synthon-II and synthon-IV; (b) 2D network formed by the one-dimensional chains via C−H···O hydrogen bonds, N···S interactions and aromatic interactions.

Neutral Complex of H41 with Phenazine. The asymmetric unit in 13 is constituted by one-half unit of H41, two half units of phen and one water molecule. All the four COOH groups of H41 involved in intermolecular hydrogen bonds: two of them link to each other via water molecules to form a onedimensional chain while the other two link one of the phenazine units to yield a two-dimensional layer (Figure 10a). Water molecules that are inserted in −COOH dimer also have been linked through second phenazine unit to form a threedimensional network (Figure 10b). In the other words, water exhibits coordination number three: two to −COOH groups and one to phenazine unit. The linked phenazine units stack on each other through aromatic π···π interactions (Figure 10d). Ionic Complexes of H41 with Bis-N-oxides. In the crystal structures of 14 and 15, the asymmetric unit of 14 is constituted by two units each of H21 and H2bpn while that of 15 is constituted by half units of H21 and H2dabn. The bpn and dabn molecules were found to be doubly protonated which is well evidenced by the bond lengths of C−O and N−O. In the database, only two examples were found in which bpn is doubly protonated: one is AuCl3 complex of bpn (N−O: 1.348, 1.351 Å) and the other is HCl complex of bpn (N−O: 1.370 and

single crystal of complexes 10−12. In all three complexes the ratios of the components of H41 and dibasic compound are similar (2:1) but differ from the complexes of 7−9. Further, the H41 is monodeprotonated while the dibases are doubly protonated. In all three cases, one −COOH involved in intramolecular hydrogen bonding while the other two involved in intermolecular hydrogen bonding. However, the crystal structures differ significantly from each other. In case of 10, the anions self-assemble to form 2D-layer containing square cavities, these layers further assembled into threedimensional networks by linking the carboxylates with H2dab units (Figure 8a,b). Two of these 3D-networks interpenetrate such that the square cavities of 2D-layers filled by the H2dab units (Figure 8c). In the complex 11, the anions form one-dimensional chains which are linked further by H2bpye units to form two-dimensional layers which have corrugated geometry (Figure 9a). These layers pack in the lattice such that the crests of one-layer fit into troughs of the adjacent layers (Figure 9b). In case of 12, the anions form 1D-chains which are linked into highly corrugated 2D-layers by bent H2bpys units and H2O molecules (Figure 9c,d). H2bpys unit found to be disordered. 3237



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adjacent layers. In 15, the H21 anions self-assemble via COO−···HOOC interactions to form one-dimensional chains which are linked further by H2dabn units to form twodimensional layers (Figure 11b,c).

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CONCLUSIONS

The anions of tetra carboxylic acid H41 exhibited versatility in self-assembling with themselves and also with cations. The molecule H41 despite of having S4 symmetry the probability of forming diamondoid architecture either as a single component or as two component system was found to be very low. Among the several complexes of H41 studied by us (present and past), the diamondoid architecture was isolated in only one-structure to date. However, in majority of the cases the S4 symmetry of H41 lead to the formation of two-dimensional layered structures via hydrogen bonding. The H41 itself was shown to form a layered structure via synthon-I containing square cavities which are occupied by acetic acid dimers. The bases used have shown the ability to convert H41 to H31 or H21 anions. The bases such as bpye, bpys and dabco found to doubly protonated in concentrated solutions but singly protonated in dilute solutions. Notably, in the crystal structures the H31 anion found to selfassemble in six ways: two types of one-dimensional zigzag chains (Figure 9a,c) and four types of two-dimensional layers (Figures 4a,c, 6a, and 8a). On the other hand H21 anion exhibited two types of one-dimensional chains (Figures 5a and 11b). Apart from the synthons I-IV, some other important hetero synthons V−IX (Scheme 2) are observed in the crystal structures. Among all the bases only phenazine was found to form neutral complex, 13 (cocrystal hydrate) with H41. The protonated N-oxides (H2bpn and H2dabn) were found to form polar hydrogen bonded networks in the crystal structures of 14 and 15. We note here diprotonated species of dabn and bpn reported here are first of their kind in the crystal structures of carboxylic acid containing complexes.

Figure 8. Illustrations for the crystal structures of 10: (a) Assembling of anions (H31) to form 2D-layer containing square cavities filled by disordered H2dab units; (b) side view of the layer with cavities occupied as well as connected H2dab units; (c) doubly interpenetrated hydrogen bonded 3D-networks.

1.368 Å). 12 From the CSD, the nonprotonated N−O distances of bpn are found to be in the range of 1.277 to 1.338 Å with average distance of 1.316 Å (averaged over 80 structures). The N−O distances observed in the present structures are significantly higher than the average N−O distance: 1.362(7), 1.338(6), 1.357(7), and 1.349(7) Å in 14 and 1.384(3) Å in 15. In both the structures the H21 units do not exhibit intramolecular hydrogen bonds. In 14, the H2bpn and H21 units exhibit self-complementarity in exhibiting four connections each. As a result it forms corrugated two-dimensional layer with (4,4)-connectivity, the layer contains two types of cavities: square and rectangular (Figure 11a). These cavities are filled by

Figure 9. Illustrations for the crystal structures of 11 and 12: (a) two-dimensional corrugated layer assembled via N+−H···O and O−H···−O hydrogen bonds between H31 and H2bpye units in the crystal structure of 11; b) side view of the layers (three layers are shown) in 11; (c) assembling of anions (H31) into one-dimensional chain in 12; (d) assembling of 1D-chains into 2D-network by bent H2bpys units and H2O molecules in 12. 3238



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Figure 10. Illustrations for the crystal structure of 13: (a) linking one-dimensional chains of (H41 units) into 2D-layers by phenazine units via O−H···N and C−H···O hydrogen bonds; (b) three-dimensional network formed by the linking of second phenazine units with water molecules; (c) stacking of the 1D chains to form two-dimsional network; (d) stacking of phenazine units of adjacent layers via π···π interactions.

Figure 11. Illustrations for the crystal structures of 14 and 15: (a) corrugated two-dimensional layer in 14; (b) self-assemble of the H21 units via COO−···HOOC interactions to form one-dimensional chain in 15; (c) one-dimensional chains are linked by H2dabn units to form two-dimensional layer in 15; (d) side view of the 2D layer.

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Preparation of Crystals of Complexes 2−15. [H41][CH3COOH]2, 2. 0.01 g of H41 (0.030 mmol) was dissolved in methanol (3 mL) by warming and acetic acid (0.5 mL) was added to this solution. The resultant solution was allowed to evaporate slowly at room temperature, colorless needle-like crystals suitable for X-ray diffraction were obtained in about 65−70% yield within 2 days. The crystals were separated from the mother liquor by filtration, washed with hexane, and dried under vacuum, Mp > 300 °C. Elemental analysis (%) calcd for C20H18O12: C, 53.34; H, 4.03. Found: C, 52.99; H, 3.82. [H31][Hpy]·H2O, 3. One equiv of H41 and four equiv of py were dissolved in methanol (8 mL) by warming. The resultant solution was allowed to evaporate slowly at room temperature, colorless block-like single crystals suitable for X-ray diffraction were obtained in about 55− 65% yield within 3−4 days. The crystals were separated from the mother

EXPERIMENTAL SECTION

All reagents were commercially available and have been used as received, with the exception of H41 and bpn, which were prepared according to the literature methods. FTIR spectra were recorded with a Perkin-Elmer Instrument Spectrum Rx Serial No. 73713. Powder XRD data were recorded with a PHILIPS Holland PW-171 defractometer. Melting point measurements were carried out using Fisher Scientific instrument Cat. No. 12-144-1. Thermogravimetric analysis (TGA) experiments were taken on a thermal analyzer from 30 to 500 °C under nitrogen atmosphere at a heating rate of 10 °C/min. The Diffuse reflectance spectra (DRS) were recorded with a Cary model 5000 UV−visible−NIR spectrophotometer. C, H, and N analyses were carried out with a PerkinElmer Series-II 2400 elemental analyzer. 3239



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Scheme 2

liquor by filtration, washed with hexane, and dried under vacuum, Mp > 300 °C. Elemental analysis (%) calcd for C21H17NO9: C, 59.02; H, 4.01; N, 3.28. Found: C, 58.66; H, 3.79; N, 3.56. Similar procedure was employed for the preparation of the crystals of 4 and 5 by taking the corresponding components. [H21][Hqun]2, 4. Colorless block-like single crystals, yield 60−65%, Mp > 300 °C. Elemental analysis (%) calcd for C34H24N2O8: C, 69.38; H, 4.11; N, 4.76. Found: C, 68.84; H, 3.83; N, 4.92. [H21][Hacr]2, 5. Light yellow colored block-like single crystals, yield 60−65%, Mp > 300 °C. Elemental analysis (%) calcd for C42H28N2O8: C, 73.25; H, 4.10; N, 4.07. Found: C, 72.76; H, 3.94; N, 4.28. [H31][Hphan]·MeOH, 6. 0.01 g of H41 (1 equiv.), and 0.011 g of phan (2 equiv.) were dissolved in methanol (8 mL) by warming. The resultant solution was allowed to evaporate slowly at room temperature; colorless rectangular plate-like single crystals suitable for X-ray diffraction were obtained in about 55−65% yield within 3−4 days. The crystals were separated from the mother liquor by filtration, washed with hexane, and dried under vacuum, Mp > 300 °C. Elemental analysis (%) calcd for C29H22N2O9: C, 64.21; H, 4.09; N, 5.16. Found: C, 63.82; H, 3.7; N, 4.68. Similar procedure was employed for the preparation of the crystals of 7−9 and 13−15 by taking the corresponding components. [H21][Hdab]2·2H2O, 7. Colorless block-like single crystals, yield 60− 65%, Mp > 300 °C. Elemental analysis (%) calcd for C28H38N4O10: C, 56.94; H, 6.48; N, 9.49. Found: C, 56.33; H, 5.91; N, 8.85. [H31][Hbpye]·H2O, 8. colorless rectangular plate-like single crystals, yield 65−70%, Mp > 300 °C. Elemental analysis (%) calcd for C28H24N2O9: C, 63.16; H, 4.54; N, 5.26. Found: C, 62.58; H, 4.16; N, 5.08. [H21] [Hbpys]2, 9. colorless needle-like single crystals, yield 65−70%, Mp > 300 °C. Elemental analysis (%) calcd for C36H26N4O8S4: C, 56.09; H, 3.40; N, 7.27. Found: C, 55.84; H, 3.28; N, 7.44. [H41][phen]2·2H2O, 13. Light green colored needle-like single crystals, yield 65−70%, Mp > 300 °C. Elemental analysis (%) calcd for C40H30N4O10: C, 66.11; H, 4.16; N, 7.71. Found: C, 65.77; H, 3.68; N, 7.47. [H21]2[H2bpn]2, 14. Colorless block-like single crystals, yield 60− 65%, Mp > 300 °C. Elemental analysis (%) calcd for C52H36N4O20: C, 60.24; H, 3.50; N, 5.40. Found: C, 59.68; H, 3.49; N, 5.89. [H21][H2dabn], 15. Colorless block-like single crystals, yield 60− 65%, Mp > 300 °C. Elemental analysis (%) calcd for C22H22N2O10: C, 55.70; H, 4.67; N, 5.90. Found: C, 55.26; H, 4.18; N, 5.64. The repeat of above reactions of H41 (0.01 g, 0.030 mmol) with 2 equiv of corresponding dibases (dab, bpye and bpys) in the 2 mL of MeOH resulted in the complexes of 10-12 respectively within 1−2 days. [H31]2[H2dab], 10. Colorless needle-like single crystals, yield 65− 70%, Mp > 300 °C. Elemental analysis (%) calcd for C38H32N2O16: C, 59.07; H, 4.17; N, 3.63. Found: C, 58.76; H, 3.61; N, 3.88. [H31]2[H2bpye], 11. Colorless needle-like single crystals, yield 65− 70%, Mp > 300 °C. Elemental analysis (%) calcd for C44H32N2O16: C, 62.56; H, 3.82; N, 3.32. Found: C, 61.98; H, 3.56; N, 3.61. [H31]2[H2bpys]·2H2O, 12. colorless needle-like single crystals, yield 65−70%, Mp > 300 °C. Elemental analysis (%) calcd for C42H32N2O18S2: C, 55.02; H, 3.52; N, 3.06. Found: C, 54.64; H, 3.30; N, 3.34.

Crystal Structure Determination. All the single-crystal data were collected on a Bruker-APEX-II CCD X-ray diffractometer that uses graphite monochromated Mo Kα radiation (λ = 0.71073 Å) at room temperature (293 K) by the hemisphere method. The structures were solved by direct methods and refined by least-squares methods on F2 using SHELX-97.17 Non-hydrogen atoms were refined anisotropically and hydrogen atoms were fixed at calculated positions and refined using a riding model.

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ASSOCIATED CONTENT

* Supporting Information S

IR-spectra, X-ray powder patterns, DRS, TGA, and crystallographic information for complexes 2−15 (CIF). This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Fax: +91-3222-282252. Tel: +91-3222-283346. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We gratefully acknowledge financial support from DST and DST-FIST for the single-crystal X-ray facility. S.R. thanks IITKGP for a research fellowship.

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REFERENCES

(1) (a) Desiraju, G. R. Angew. Chem., Int. Ed. 1995, 34, 2311. (b) Braga, D., Grepioni, F., Orpen, A. G., Eds.; Crystal Engineering: From Molecules and Crystals to Materials; Kluwer: Dordrecht, Netherlands, 1999. (c) Thayer, A. M. Chem. Eng. News 2007, 85, 17. (d) Amato, I. Chem. Eng. News 2007, 85, 27. (e) Basavoju, S.; Bostroem, D.; Velaga, S. P. Cryst. Growth Des. 2006, 6, 2699. (f) Trask, A. V.; Motherwell, S. W. D.; Jones, W. Int. J. Pharm. 2006, 320, 114. (g) Reddy, L. S.; Babu, J. N.; Nangia, A. Chem. Commun. 2006, 1369. (h) Remenar, J. F.; Morissette, S. L.; Peterson, M. L.; Moulton, B.; MacPhee, J. M.; Guzman, H. R.; Almarsson, Ö . J. Am. Chem. Soc. 2003, 125, 8456. (i) Almarsson, Ö .; Zaworotko, M. J. Chem. Commun. 2004, 1889. (j) Bingham, A. L.; Hughes, D. S.; Hursthouse, M. B.; Lancaster, R. W.; Tavener, S.; Threlfall, T. L. Chem. Commun. 2001, 603. (k) Holman, K. T.; Pivovar, A. M.; Swift, J. A.; Ward, M. D. Acc. Chem. Res. 2001, 34, 107. (2) Lawrence, D. S.; Jiang, T.; Levett, M. Chem. Rev. 1995, 95, 2229. (3) (a) Reddy, D. S.; Craig, D. C.; Desiraju, G. R. J. Am. Chem. Soc. 1996, 118, 4090. (b) Desiraju, G. R. Chem. Commun. 1997, 1475. (c) Steed, J.; Atwood, J. L. Supramolecular Chemistry; Wiley: Chichester, 2000. (d) Etter, M. C. Acc. Chem. Res. 1990, 23, 120. (4) (a) Sharma, C. V. K.; Zaworotko, M. J. Chem. Commun. 1996, 2655. (b) Zaworotko, M. J. Chem. Commun. 2001, 1. (c) Pedireddi, V. R.; Jones, W.; Chorlton, A. P.; Docherty, R. Chem. Commun. 1996, 997. (d) Batchelor, E.; Klinowski, J.; Jones, W. J. Mater. Chem. 2000, 10, 839. 3240



Article

(e) Anthony, A.; Desiraju, G. R. Supramol. Chem. 2001, 13, 11. (f) Aakeröy, C. B.; Beatty, A. M.; Zou, M. Cryst. Eng. 1998, 1, 225. (g) Mnajare, Y.; Pedireddi, V. R. Cryst. Growth Des. 2011, 11, 5079. (h) Mei, X.; Wolf, C. Eur. J. Org. Chem. 2004, 4340. (i) Bhogala, B. R.; Vishweshwar, P.; Nangia, A. Cryst. Growth Des. 2002, 2, 325. (j) Biradha, K. CrystEngComm 2003, 5, 274. (k) Bhogala, B. R.; Nangia, A. Cryst. Growth Des. 2003, 3, 547. (l) Arora, K. K.; Pedireddi, V. R. J. Org. Chem. 2003, 68, 9177. (5) (a) Walsh, R. D. B.; Bradner, M. W.; Fleischman, S.; Morales, L. A.; Moulton, B.; Rodríguez-Hornedob, N.; Zaworotko, M. J. Chem. Commun. 2003, 186. (b) Lemmerer, A. CrystEngComm. 2012, 14, 2465. (c) Aakeröy, C. B.; Forbes, S.; Desper, J. CrystEngComm. 2012, 14, 2435. (d) Grobelny, P.; Mukherjee, A.; Desiraju, G. R. CrystEngComm. 2011, 13, 4358. (e) Lemmerer, A.; Bernstein, J.; Kahlenberg, V. CrystEngComm. 2010, 12, 2856. (f) McHugh, C.; Erxleben, A. Cryst. Growth Des. 2011, 11, 5096. (g) Sarcevica, I.; Orola, L.; Veidis, M. V.; Podjava, A.; Belyakov, S. Cryst. Growth Des. 2013, 13, 1082. (h) Goswami, P. K.; Thaimattam, R.; Ramanan, A. Cryst. Growth Des. 2013, 13, 360. (i) Takasuka, M.; Nakai, H.; Shiro, M. J. Chem. Soc., Perkin Trans. 2 1982, 1061. (j) Bhattacharya, S.; Saha, B. K. Cryst. Growth Des. 2011, 11, 2194. (k) Samai, S.; Biradha, K. CrystEngComm 2009, 11, 482. (6) (a) Johnson, S. L.; Rumon, K. A. J. Phys. Chem. 1965, 69, 74. (b) Bhogala, B. R.; Basavoju, S.; Nangia, A. CrystEngComm. 2005, 7, 551. (c) Men, Y. B.; Sun, J.; Huang, Z. T.; Zheng, Q. Y. CrystEngComm. 2009, 11, 978. (d) Reddy, L. S.; Bethune, S. J.; Kampf, J. W.; Hornedo, N. R. Cryst. Growth Des. 2009, 9, 378. (7) (a) Weyna, D.; Shattock, R. T.; Vishweshwar, P.; Zaworotko, M. J. Cryst. Growth Des. 2009, 9, 1106. (b) Shattock, T. R.; Vishweshwar, P.; Wang, Z.; Zaworotko, M. J. Cryst. Growth Des. 2005, 6, 2046. (c) Bhogala, B. R.; Basavoju, S.; Nangia, A. Cryst. Growth Des. 2005, 5, 1683. (8) (a) Santra, R.; Ghosh, N.; Biradha, K. New J. Chem. 2008, 32, 1673. (b) Santra, R.; Biradha, K. Cryst. Growth Des. 2009, 9, 4969. (9) (a) Men, Y. B.; Sun, J.; Huang, Z. T.; Zheng, Q. Y. CrystEngComm 2009, 11, 978. (b) Roy, S.; Mahata, G.; Biradha, K. Cryst. Growth Des. 2009, 9, 5006. (c) Biradha, K.; Mahata, G. Cryst. Growth Des. 2005, 5, 49. (10) (a) Roy, S.; Biradha, K. Cryst. Growth Des. 2011, 11, 4120. (b) Mahata, G.; Roy, S.; Biradha, K. Chem. Commun. 2011, 47, 6614. (11) (a) Roy, S.; Mondal, S. P.; Ray, S. K.; Biradha, K. Angew. Chem., Int. Ed. 2012, 51, 12012. (b) Kapadia, P. P.; Ditzler, L. R.; Baltrusaitis, J.; Swenson, D. C.; Tivanski, A. V.; Pigge, F. C. J. Am. Chem. Soc. 2011, 133, 8490. (12) (a) Leblanc, N.; Allain, M.; Mercier, N.; Cariati, E. Cryst. Growth Des. 2011, 11, 5200. (b) Bourne, S. A.; Moitsheki, L. J. Polyhedron 2008, 27, 263. (13) Holý, P.; Závada, J.; Císařová, I.; Podlaha, J. Angew. Chem., Int. Ed. 1999, 38, 381. (14) (a) Rajput, L.; Jana, N.; Biradha, K. Cryst. Growth Des. 2010, 10, 4565. (b) Rajput, L.; Santra, R.; Biradha, K. Aust. J. Chem. 2010, 63, 578. (c) Rajput, L.; Chernyshev, V. V.; Biradha, K. Chem. Commun. 2010, 46, 6530. (15) (a) Shimizu, L. S.; Hughes, A. D.; Smith, M. D.; Davis, M. J.; Zhang, B. P.; zur Loye, H.-C.; Shimizu, K. D. J. Am. Chem. Soc. 2003, 125, 14972. (b) Csoregh, I.; Czugler, M.; Weber, E.; Ahrendt, J. J. Inclusion Phenom. Mol. Recog. Chem. 1990, 8, 309. (c) Vishweshwar, P.; Beauchamp, D. A.; Zaworotko, M. J. Cryst. Growth Des. 2006, 6, 2429. (d) Skobridis, K.; Paraskevopoulos, G.; Theodorou, V.; Seichter, W.; Weber, E. Cryst. Growth Des. 2011, 11, 5275. (16) Biradha, K.; Zaworotko, M. J. Cryst. Eng. 1998, 1, 67. (17) Sheldrick, G. M. SHELX-97, Program for the Solution and Refinement of Crystal Structures; University of Gottingen: Gottingen, Germany, 1997.

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