Polymorphs of 1-(5-Methylthiazol-2-yl)-3 ... - ACS Publications

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Polymorphs of 1‑(5-Methylthiazol-2-yl)-3-phenylthiourea and Various Anion-Assisted Assemblies of Two Positional Isomers Nithi Phukan and Jubaraj B. Baruah* Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India S Supporting Information *

ABSTRACT: Orientations of the phenyl group and the intramolecular hydrogen bond play prime roles in the packing patterns of three conformational polymorphs of an unsymmetrical thiourea derivative, 1-(5-methylthiazol-2-yl)-3-phenylthiourea (PTH1). Self-assembly of each polymorph is composed of hydrogen-bonded dimeric motifs held together in head-to-tail arrangement but packed in different manners. Each has an intramolecular N−H···N hydrogen bond between an amide N−H and the nitrogen atom of the 5-methylthiazole unit. The packing pattern of 1-(4-methylthiazol-2yl)-3-phenylthiourea (PTH2) is composed of dimeric assemblies of PTH2 in head-to-tail fashion. PTH2 is monomorphic as there are intermolecular C−H···S interactions between a C−H bond of the phenyl ring of each molecule and the sulfur atom of the thiocarbonyl group of a neighboring molecule. Such interactions lock the orientation of phenyl group in the solid state. The syn−anti conformation across the thiourea group, originally present in the positional isomers PTH1 and PTH2, is invariably transformed to syn−syn conformation in their salts. The extent of hydration of anions in the salts of PTH1 or PTH2 is dependent on the cation as well as the anion. The chloride salt of PTH1 has a large difference in packing patterns in comparison with the corresponding chloride salt of PTH2; they also differ in the numbers of symmetry-nonequivalent molecules in their respective unit cells. The anhydrous salt of PTH1 with hydrogen bromide having a 1:1 ratio of cation and anion is formed, whereas the bromide salt of PTH2 is a hydrate of composition (HPTH2)2(Br)2·6H2O. This salt has bromide−water clusters in its crystal lattice. Nitric acid reacts with PTH1 under different conditions to form hydrated or anhydrous salts. The hydrated salt (HPTH1)2(NO3)2·H2O has anions bridged by water molecules. The anhydrous nitrate salts of PTH1 and PTH2 are structurally similar in having nitrate···nitrate interactions. The deprotonation of polyacids by PTH1 and PTH2 is selective. The ability to abstract a proton from sulfuric acid to form crystalline salts by PTH1 and PTH2 differs. The sulfate salt (HPTH1)2(SO4) is formed by reaction of sulfuric acid with PTH1, but PTH2 forms the bisulfate salt (HPTH2)HSO4·H2O. PTH1 forms the corresponding dihydrogen phosphate salt upon reaction with orthophosphoric acid; the dihydrogen phosphate anions are held together in the form of cyclic hydrogen-bonded hexameric assemblies in the lattice. Water loss from the assemblies of hydrated salt was determined by thermogravimetry and differential scanning calorimetry and showed that dehydration from anion-assisted assemblies was guided by the cationic host and the type of assembly.

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INTRODUCTION The supramolecular chemistry of thiourea stems from its ability to form channel-like structure to include various guest molecules.1 Thiourea derivatives are used as anion transporters.2 The channel formed by self-assembly of thiourea molecules can include inorganic molecules such as ferrocene.3 Certain biological processes are studied with the aid of thiourea channels.4 From a crystal engineering perspective, studies on the polymorphism5 and solvates of thiourea-based molecules have gained interest.6 On the other hand, the ease of functionalizing thiourea has helped to grow the area of research on such compounds to a vast domain. In particular, thioureacontaining ligands are good host for anions,7 and some of them behave as anion sensors.8 The ability of thiourea derivatives to form strong hydrogen bonds is utilized in organocatalysis9 and in nonlinear optics.10 In contrast to the structure of symmetric urea derivatives in the solid state,11 understanding of the factors dictating the solid-state structures of substituted thioureas have remained elusive.12 The ability to form syn−syn or syn−anti geometries (Chart 1a,b) by symmetric N,N-disubstituted thiourea derivatives are well-documented in literature.13 © 2014 American Chemical Society

Locking of such geometries by weak interactions may help to generate interesting packing patterns. Since the energy of C−C bond rotation for conformational changes is comparable to weak hydrogen bonds,14 subtle changes by electronic or steric factors should generate different structural motifs in thiourea derivatives. We have earlier shown that conformational changes can be achieved in an unsymmetric urea derivative by coordination effects.13b Now, we choose two thiourea derivatives, namely, 1-(5-methylthiazol-2-yl)-3-phenylthiourea (PTH1) and 1-(4-methylthiazol-2-yl)-3-phenylthiourea (PTH2) (Chart 1c), with an anticipation to stabilize different solid-state conformers such as A−D shown in Chart 1. In this study, we establish that syn−anti conformation prevails in the two positional isomers PTH1 and PTH2 due to intramolecular hydrogen bonds, and we also show that PTH1 easily forms conformational polymorphs whereas PTH2 does not. The structures of various salts of the two thiourea derivatives were Received: March 8, 2014 Revised: April 7, 2014 Published: April 11, 2014 2640

dx.doi.org/10.1021/cg5003379 | Cryst. Growth Des. 2014, 14, 2640−2653

Crystal Growth & Design

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Chart 1. (a, b) Two Different Geometries of Symmetric Thiourea, (c) Positional Isomers of Methylthiazole-Functionalized Phenylthiourea, and (d) Conformers of PTH1 and PTH2

Figure 1. (a) Crystal morphologies and different Z′ values of PTH1 polymorphs. (b−d) PXRD patterns of (b) PTH1a, (c) PTH1b, and (d) PTH1c (in each case top/red = experimental and bottom/blue = simulated).

generated from the CIF files by MERCURY software tally with the experimental diffraction patterns (Figure 1b−d). These observations indicated that the solvents guided the crystallization of these polymorphs. Similar results were reported recently from the solvent-guided crystallization of polymorphs in an amide-bond-containing compound.15 Crystal packing of PTH1a shows that the N atom of the 5methylthiazole unit is engaged in intramolecular N−H···N interaction with the thiourea N−H proton with N···N distance 2.70 Å and N−H···N bond angle 139° (Table 1, Figure 2a). This provides a syn−anti orientation across the thiourea units. The molecules form dimeric assemblies, which are associated with cyclic R2 2 (8) hydrogen bonds through N−H···S interactions. Polymorph PTH1b possesses two symmetry-independent molecules (X and Y) in its crystallographic asymmetric unit as shown in Figure 2b. Each symmetry-independent molecule has

determined to establish the syn−syn geometries prevalent in these salts.

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RESULTS AND DISCUSSION Three polymorphs of PTH1, abbreviated as PTH1a, PTH1b, and PTH1c, were crystallized from the respective solutions of PTH1 in methanol, tetrahydrofuran, or dimethylformamide. The crystal morphologies of these three polymorphs are distinguishable, as shown in Figure 1a. Structures of the three polymorphs were determined by single-crystal X-ray diffraction and they belong to space groups P21/c, P1̅, and C2/c, respectively. The respective crystal densities of the polymorphs are 1.363, 1.393, and 1.377 g/cm3. Since the three polymorphs were obtained by independent crystallization from three different solvents, we have checked their phase purity by analyzing their experimentally determined powder X-ray diffraction (PXRD) patterns. The simulated PXRD patterns 2641



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Polymorphs PTH1a and PTH1c have structural similarities. The packing pattern of PTH1c is composed of identical hydrogen-bonded motifs, as in PTH1a, but there are differences in hydrogen-bond parameters as well as torsion angles. Polymorph PTH1c also possesses intramolecular hydrogen bonds, in which the donor−acceptor bond distance dD···A is 2.68 Å and N−H···N bond angle is 140°. Polymorph PTH1c has R22(8) hydrogen-bond motifs containing N−H···S interactions (Table 1). The common feature of the three polymorphs is the presence of homomeric R22(8) hydrogen-bond assemblies. Recently, similar assemblies in benzoyl-carvacryl thiourea derivatives forming planar dimeric chain were reported.16 We have observed differences among the arrangements of dimeric assemblies present in the respective crystal lattices of the polymorphs. Assemblies of PTH1a comprise hydrogen-bonded dimeric molecules arranged in such a way that, when viewed along a sequence of linearly placed molecules in the lattice, these are related by a 21 screw axis. Thus, phenyl groups present on alternate molecules are oriented toward opposite sides (Figure 2c). On the other hand, there are two symmetryindependent molecules in the hydrogen-bonded dimer of PTH1b. These dimers occur in pairs, forming a sheetlike arrangement (Figure 2d). In such an arrangement, the phenyl groups of molecules in the next layer are placed nearly perpendicular to each other. On the other hand, in the lattice of PTH1c the molecules are positioned in an orderly manner

Table 1. Hydrogen-Bond Parameters in PTH1 Polymorphs and in PTH2 D−H···A N(2)−H(2) ···S(2) [−x, 1 − y, −z] N(3)−H(3) ···N(1) N(2)−H(2)···S(4) [−x, 1 − y, −z] N(3)−H(3)···N(1) N(5)−H(5)···S(2) [−x, 1 − y, −z] N(6)−H(6)···N(4)

dD−H (Å)

dH···A (Å)

PTH1a 0.79(2) 2.55(2)

dD···A (Å)

∠D−H···A (deg)

3.315(2)

163(2)

0.85(2) 2.01(2) PTH1b 0.86 2.54

2.708(3)

139(2)

3.361(3)

161

0.86 0.86

1.98 2.54

2.716(5) 3.355(3)

143 158

1.95

2.691(6)

144

1.97 2.54

2.685(3) 3.345(2)

140 155

PTH2 0.85(3) 2.50(3)

3.331(4)

164(3)

0.86(3) 0.93

2.695(5) 3.843

133(3) 157

0.86 PTH1c

N(3)−H(2) ···N(1) N(2)−H(3)···S(2) [1/2 − x, −1/2 − y, −z] N(2)−H(2) ···S(2) [2 − x, 2 − y, 1 − z] N(3)−H(3A) ···N(1) C(11)−H ···S(2)

0.86 0.86

2.03(4) 2.97

independent intramolecular N−H···N interactions (Figure 2b): dD···A distances are 2.72 and 2.69 Å and N−H···N bond angles are 143° and 144°, respectively (Table 1).

Figure 2. (a) Assembly of PTH1a having intramolecular N−H···N and intermolecular N−H···S interactions. (b) Assembly of two symmetrynonequivalent molecules in the crystal lattice of PTH1b. (c−e) Packing patterns of (c) PTH1a, (d) PTH1b, and (e) PTH1c. (f) Overlay diagram showing orientations of the phenyl group in three polymorphs of PTH1 (drawn by fixing the 5-methylthiazole planes in one direction). 2642



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Figure 3. (a) Representation of the plane of the phenyl ring with respect to the thioamide plane in PTH1 and PTH2. (b) Hydrogen bonds in structure of PTH2 (drawn with 30% thermal ellipsoids).

Figure 4. Weak interactions in chloride salts (a) 1a and (b) 1b.

along the b-crystallographic axis such that the phenyl rings are present on one side. Such chains occur in pairs, in which two chains are related by a mirror plane of reflection (Figure 2e). Thus, it is clear that the three polymorphs result from differences in the arrangements of their dimeric assemblies. On the other hand, there are differences in orientations of the phenyl groups with respect to a plane containing the 5methylthiazole unit as illustrated in Figure 2f. These differences occur due to free rotation of the phenyl group connected to the thioamide bond. To explain the orientations, two independent planes may be constructed with dihedral angle C11−C6−N3− C5 (τ) as illustrated in Figure 3a. The dihedral angle τ is 81.91° for PTH1a and 123.06° for PTH1c, whereas PTH1b, with two symmetry-nonequivalent molecules, has dihedral angles 160.11° and 54.04° for the two symmetry-independent molecules. Thus, in each polymorph the phenyl ring lies in a different plane with respect to the thiourea plane, providing characteristic packing patterns. The polymorphism exhibited by PTH1 has generated interest in investigating the structural aspects of another positional isomer with a methyl group at another position of methylthiazole. Thus, the crystallization of PTH2 was pursued from solutions of PTH2 in different solvents such as methanol, tetrahydrofuran, and dimethylformamide; however, from all these solutions, we observed crystallization of only one form of crystals belonging to triclinic P1̅ space group. Crystal structure of PTH2 displays an intramolecular N−H···N interaction with dD···A 2.69 Å and N−H···N bond angle 133° (Table 1). It exhibits R22(8) geometry through N−H···S hydrogen bonds to

form dimeric motifs. In addition to these common features of the structures of PTH1 and PTH2, an additional feature observed in the case of PTH2 is the intermolecular C11−H··· S2 interaction with an aromatic C−H bond.16 This particular interaction resulted in the formation of a three-dimensional assembly of dimeric units (Figure 3b). The C−H bonds acting as donors are of considerable interest due to their influence on stabilization of conformers and roles in supramolecular chemistry.14 The C−H···S interactions help in locking of conformation of enantiomer to obtain a selective optical isomer.14a The dihedral angle τ of PTH2 as defined in Figure 3a is 125.08°. This shows that the orientation of the phenyl ring in any polymorph of PTH1 as well as in PTH2 is different. In the case of PTH2, we observed monomorphism, due to the C−H··· S interaction locking the orientation of the phenyl group. Differential scanning calorimetry of the three polymorphs of PTH1 showed similar features in terms of two close melting points. Differences in melting temperature ranging within a narrow span of temperatures in the range 170−182 °C were observed in each case, showing their comparable stabilities. Various closely related phase transitions were earlier shown in different polymorphs of a particular amide;17 However, we did not observe phase transition but observed only the melting points. We calculated the energies associated with the conformational polymorphs of PTH1 and with PTH2. B3LYP/6-31++g(d,p)-level calculations showed that the three polymorphs have identical energy, whereas the positional isomer PTH2 is more stable than PTH1 and the energy difference is 1.374 26 kcal/mol. PTH1b has two symmetry2643



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Figure 5. Various weak interactions in (a) 2a and (b) 2b. (c) Two units of bromide−water clusters present in 2b. (d) Thermogram of 2b (heating rate 5 °C/min).

The unit cell of the chloride salt of PTH1 (1a) contains four protonated host molecules and four chloride anions (Figure 4a); each has independent symmetry. The N+−H bond of the 5-methylthiazole unit and N−H bonds of the thiourea both act as hydrogen-bond donors and engage in hydrogen-bond formation with chloride ions. The two N−H bonds of thiourea are hydrogen-bonded to one chloride ion in each case. The assemblies of the salts have a numbers of C−H···Cl interactions: C14−H···Cl1 (dD−A = 3.60 Å), C3−H···Cl2 (dD−A = 3.59 Å), C43−H···Cl3 (dD−A = 3.81 Å), C25−H··· Cl4, C32−H···Cl4 (dD−A = 3.71 Å), etc. The chloride ions are arranged along the b-crystallographic axis with a channel-like arrangement of the cations [HPTH1]+ (Figure S44, Supporting Information). The asymmetric unit of the chloride salt of PTH2 (1b) contains one protonated host molecule and one chloride anion. Similar to salt 1a, N+−H of the 4-methylthiazole unit and both N−H bonds of thiourea act as hydrogen-bond donors and engage in hydrogen-bond formation with the chloride ions, forming an end-capped dimeric structure (Figure 4b). Although these chloride salts 1a and 1b crystallizes in the same space group, they differ in Z′ values. The packing patterns of 1a and 1b are different (Figure S44, Supporting Information). Salt 1b also has hydrogen bonds involving the chloride ions to anchor the [HPTH2]+ ions through N1−H···Cl1 (dD···A = 3.06 Å), N2−H···Cl1 (dD···A = 3.18 Å), and N3−H···Cl1 (dD···A = 3.17 Å) interactions. Assembly of the [HPTH2]+ ions forms a onedimensional sheetlike structure. In both cases, N−H···Cl

independent molecules in its crystallographic unit cell, so, we have treated both conformers separately to calculate individual energies and took the average of the two energy values. Packing effects were ignored as we carried out gas-phase calculations. The Z values for PTH1a and PTH1b are 4, whereas the Z value for PTH1c is 8. On the other hand, the Z′ values of PTH1a, PTH1b, and PTH1c are 1, 2, and 1, respectively. The higher Z′ values are generally associated with metastable states18 In this case, the polymorph with higher Z′ value is not a metastable state; it also has equal energy with the other polymorphs. The role of solvent in generating different Z′ values was revealed earlier by isolation of different solvates of the same compound with different Z′ values.19 The present results on selective crystallization of polymorphs from particular solvents has provided support for the role of solvent in stabilization of different conformers. We have determined the structures of salts of PTH1 and PTH2 prepared by reacting them independently with different acids. We isolated crystalline salts of PTH1 after reaction with hydrochloric acid (1a), hydrobromic acid (2a), nitric acid (3a and 3.1a), perchloric acid (4a), sulfuric acid (5a), and phosphoric acid (6a). We also isolated crystalline salts of PTH2 from reactions with hydrochloric acid (1b), hydrobromic acid (2b), nitric acid (3b), perchloric acid (4b), and sulfuric acid (5b). Each salt is composed of host(s), protonated at the nitrogen atom of methylthiazole unit, and corresponding hydrated or anhydrous anion(s). 2644



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Figure 6. Hydrogen bonds in nitrate salts (a) 3a, (b) 3.1a, and (c) 3b.

hydrogen bonds are present, which make R16(6) hydrogenbond motifs. Crystals of the bromide salt of PTH1 (2a) belong to monoclinic I2/c space group. The crystallographic asymmetric unit contains one molecule of protonated host and one bromide anion. The N+−H bond of the 5-methylthiazole unit and both N−H bonds of the thiourea unit act as hydrogenbond donor to the bromide anion (Figure 5a). Apart from this, the sulfur atom of the thiocarbonyl group participates in a C− H···S interaction with the methyl proton of methylthiazole. Such interactions lead to one-dimensional polymeric sheetlike structure, where bromide ions are intercalated between two oppositely oriented protonated PTH1 molecules along the bcrystallographic axis (Figure S45, Supporting Information). The bromide salt of PTH2 (2b), is a trihydrate, but it is observed in the form of a dimeric assembly with composition (HPTH2) 2 (Br) 2 ·6H 2 O. The crystals of 2b belong to monoclinic space group P21/n. The crystallographic asymmetric unit of 2b contains two protonated host molecules, two bromide anions, and six water molecules from crystallization. The cationic host [HPTH2]+ provides the required platform to accommodate a bromide−water cluster [(Br)2(H2O)6]2−. The bromide−water cluster held between the cations is shown in Figure 5b. Each octameric cluster consisting of two bromide anions and six water molecules is connected to another similar octameric cluster through O−H···Br via R22(8) hydrogen-bond motifs. The cluster looks like an octahedron where bromide ions occupy the opposite vertices. The two different bromide anions are strongly held in the lattice through several O−H···Br interactions, as depicted in Figure 5c. A discrete cubane-like bromide−water cluster was stabilized in pyridylphosphine iron(II) complex,20 but in the present case we find a new octameric cluster. The number of water molecules in 2b was also confirmed by thermogravimetry. Salt 2b loses 27.1% (calculated 28%) of its weight, corresponding to the loss of six water molecules (Figure 5d), at temperature range 48−140 °C. We obtained hydrated and anhydrous form of nitrate salts of PTH1, namely, (HPTH1)2(NO3)2·H2O (3a) and (HPTH1)NO3 (3.1a). The hydrated form 3a was obtained from reaction in aqueous methanol solution of PTH1 and the crystals belong to triclinic space group P1,̅ while the crystals of anhydrous form 3.1a were obtained from reaction of PTH1 with nitric acid in dry methanol and crystallize in monoclinic space group P21/n. Structural analysis of 3a revealed that the primary interactions of one nitrate ion are established through N−H···O hydrogen

bonds, forming R22(8) motifs between the thiourea moiety of the protonated host and nitrate ion (Figure 6a). There are two symmetry-nonequivalent nitrate ions in the unit cell; these ions are bridged by water molecules through O−H···O interactions. The oxygen atom O4 forms two hydrogen bonds, while the O3 atom is involved in three hydrogen bonds. The hydrogen bonds of N6−H··· O4 and O7−H···O4 have dD···A 2.85 and 2.83 Å and ∠D−H···A angles 167° and 165°, respectively. The hydrogen bonds associated with O3 to connect N3−H, C11−H, and O7−H have D···A distances of 2.816(3)− 2.799(4) Å, which are in the range permissible to have weak interactions.14 The asymmetric unit of the anhydrous nitrate salt contains two protonated host molecules and two nitrate ions. As the two NO3− ions are symmetrically nonequivalent, only one of the nitrate ions is involved in the R22(8) motif formed by N−H···O hydrogen bonds between the thiourea moiety of the protonated host and nitrate ion (Figure 6b). The O1, O2, and O4 atoms are involved in formation of bifurcated hydrogen bonds. Unlike the hydrated form 3a, in 3.1a there is no water molecule bridging between the nitrate ions. Nitrate··· nitrate interactions among the anions are observed in the solidstate structure of 3.1a (Figure 6b). Nitrate···nitrate interactions in urea derivatives in the solid state were reported earlier,21 which had shorter oxygen···oxygen distances than the distances observed by us. Nitrate···nitrate interactions in the solid state have a role in the packing of nitrate salts.22 We also find a similar observation as shown in the packing diagram of anhydrous nitrate salt (Figure S46b, Supporting Information). The thermogram of the hydrated salt showed that 3a loses a water molecule at 80.3 °C and the compound is unstable above 130 °C. When PTH2 was acidified with nitric acid, we obtained only the anhydrous form (HPTH2)NO3 (3b), which crystallizes in monoclinic space group P21/n. The crystallographic asymmetric unit of the salt contains two protonated host molecules and two planar NO3− anions. PTH2 is coordinated with nitrate ion through N−H···O, N+−H···O−, and C−H···O interactions (Figure 6c). Like 3a and 3.1a, there are no cyclic hydrogen bonds among the thiourea unit and the nitrate ions in 3b. But as in the case of 3.1a, salt 3b also has nitrate···nitrate interactions. If the phenyl-bearing group is considered as head and the methylthiazole-bearing end as tail, then the packing pattern of the hydrated nitrate salt of PTH1 has a head-to-head arrangement of [HPTH1]+ along the b-crystallographic axis; whereas in the anhydrous salt they are arranged in a nonparallel 2645



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Figure 7. Weak interactions between perchlorate ions and (a) (HPTH1)+ in 4a and (b) (HPTH2)+ in 4b. (c) R35(14) and R34(12) hydrogen-bond motifs in salt 4a. (d) R24(8) and R44(12) hydrogen-bond motifs in salt 4b.

obtained from the reaction of perchloric acid with PTH2. The hydrogen-bond environment around perchlorate anion of hydrated salt 4b is shown in Figure 7b. The thermogram of this hydrate 4b differ from the dihydrate salt 4a and it loses water molecules at 90 °C, which is much lower than the temperature required in the case of dihydrate salt 4a. In the structure of 4b, the thiourea N−H and N+−H of the 4methylthiazole moiety act as hydrogen-bond donors. The O2 and O5 atoms are involved in bifurcated hydrogen bonds. The monohydrate salt of PTH2 has water molecules participating in R24(8) and R44(12) motifs comprising O−H···O hydrogen bonds with the perchlorate ions (Figure 7d). This hexameric cyclic hydrogen-bonded assembly formed by perchlorate ions and water molecules looks like an open book. Similar openbook-like assemblies were earlier observed in water hexamers.24 Thus, comparison of the thermograms and structural patterns shows that thermal stabilities of hydrated anionic assemblies differ and the environment around the assemblies of hydrated anions as well as the types of anion-assisted assemblies decide the loss of water molecules from such assemblies of hydrated anions and water loss may occur below or above the normal boiling point of water. The asymmetric unit of the sulfate salt of PTH1, (HPTH1)2SO4 (5a), belongs to triclinic space group P1̅ and contains two protonated host molecules and one sulfate ion. Structural analysis of the salt shows that one sulfate ion

manner. This suggests that water molecules play a role in the arrangement of the host molecules in the lattice of 3a. The perchlorate salt (HPTH1)ClO4·2H2O (4a) crystallizes in monoclinic space group P21/a. The asymmetric unit contains one protonated host molecule, one perchlorate anion, and two water molecules from crystallization. The two N−H bonds, N2−H and N3−H (Figure 7a), are connected to a water molecule through N2−H···O6 and N3−H···O6 interactions. Two hydrogen-bonded water molecules are positioned linearly between two perchlorate anions. The O1, O2, O5, and O6 atoms are independently involved as hydrogen-bond acceptors. The perchlorate anion interacts with the water molecules, forming R35(14) and R34(12) motifs resulting in O−H···O hydrogen bonds (Figure 7c). Perchlorate anion with the aid of hydrogen bonds achieves water-assisted three-dimensional assembly (Figure S47, Supporting Information). The xanthine perchlorate salt is a dihydrate,23 in which the water molecules form hydrogen bonds with two donor sites and one acceptor site. In comparison to this, salt 4a is also a dihydrate, but in this case water molecules participate in hydrogen bonds by providing two acceptor and two donor sites. In thermogravimetry the two water molecules of salt 4a are lost at 120 °C (Figure S52, Supporting Information), which is a relatively higher temperature for evaporation of water molecules, showing that they are tightly held in the interstices. On the other hand, a monohydrate salt, (HPTH2)ClO4·H2O (4b), was 2646



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Figure 8. (a) Crystal structure of (HPTH1)2(SO4) showing environment of a sulfate ion. (b) Weak interactions of bisulfate ions in the salt 5b. (c) R44(12) hydrogen-bond motif in bisulfate−(water)2−bisulfate assembly formed within 5b.

Figure 9. (a) Self-assembly of (HPTH1)H2PO4 (6a). (b) Hydrogen-bonded cyclic hexamer of the dihydrogen phosphate ions present in the lattice of 6a.

that bisulfate salts find application in various devices such as sensors and batteries.25 A sulfate−(water)3−sulfate assembly stabilized by urea-based receptor was reported earlier.26 Bisulfate binding to crown ethers was also reported.27 Besides these, one-dimensional bisulfate−water chainlike structure and two-dimensional sulfate−water anionic sheet in the solid state28 were established earlier. But in our case, [HPTH2]+ ions interact with water molecules in the lattice through O−H···O interactions from two sides, forming R44(12) motifs, which were not observed earlier in the bisulfate−water chains. Salt 5b loses water molecules upon heating, which is reflected as two endothermic peaks at 55 and at 98 °C in differential scanning calorimetry, and 4.8% weight loss was observed in the range 55−98 °C in thermogravimetry (Figure S54, Supporting Information). The corresponding theoretical loss for one molecule of water is 4.9% . Thus, the loss of water molecules occurs in two steps. In the hydrated bisulfate assembly, two water molecules bridges two bisulfate anions (Figure 8b). One of the bridging water molecules is lost at low temperature to modify the assembly, and the second loss occurs at relatively higher temperature from a reconstructed hydrated assembly formed by loss of one water molecule at a lower temperature. Thus, overall one water molecule per bisulfate anion is lost. The reaction of orthophosphoric acid with PTH1 forms (HPTH1)H 2PO4 (6a); crystals of this salt belong to monoclinic space group C2/c. As shown in Figure 9a, in the structure of salt 6a both the N−H bonds of thiourea and the N−H bond of the protonated 5-methylthiazole act as

interacts with four neighboring (HPTH1)+ ions as shown in Figure 8a. Among the four (HPTH1)+ ions, two are connected through R22(8) motifs of N−H···O hydrogen bonds between (HPTH1)+ and sulfate ions. The other two cations are connected through N+−H···O− interactions. The oxygen atom (O4) of the sulfate ion is involved in three N−H···O interactions. A similar structural pattern involving sulfate anion was observed in a urea derivative.22 The O1 and O2 atoms of the cationic part act as hydrogen-bond acceptors in N−H···O and N+−H···O− interactions (dO1···N5 = 2.66 Å; dO2···N3 = 2.93 Å; dO2···N6 = 2.90 Å) respectively. It has a parallel sheetlike structure along the b-crystallographic axis (Figure S48, Supporting Information). On the other hand, the reaction of PTH2 with sulfuric acid enabled us to isolate only the hydrated crystalline bisulfate salt, (HPTH2)HSO4·H2O (5b). Interactions of the bisulfate ion with PTH2 and water molecules in the lattice are shown in Figure 8b. Each bisulfate anion interacts with one PTH2 molecule and two water molecules through N−H···O and O− H···O interactions. The lattice water molecules bridge the bisulfate ions and form a R44(12) hydrogen-bond motif (Figure 8c). Atom O1 of a bisulfate ion is involved in two N−H···O interactions through N2−H and N3−H bonds of thiourea, whereas another atom O2 of bisulfate ion acts as a pivot for three hydrogen bonds with N1−H, N2−H, and O5−H bonds. The O3 atom of another bisulfate ion connects the O5−H bond of bridging water molecule. The O1 atom of bisulfate is hydrogen-bonded to N2−H and N3−H. It may be mentioned 2647



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bromide ion in salt 2a acts as a pivot of bifurcated hydrogen bonds with two N−H of thiourea to stabilize a syn−syn geometry across the thiourea, whereas in the bromide salt 2b, the oxygen of a water molecule acts as pivot for bifurcated hydrogen bonds and the water molecules bridge bromide ions. The selective deprotonated salts of polyacids, such as the one formed from sulfuric acid and orthophosphoric acid by PTH1 and PTH2, support the idea that the deprotonations are guided by stable crystalline product formation. For example, sulfuric acid is a strong acid: it selectively formed crystalline bisulfate salt with PTH2, whereas with PTH1 it formed the corresponding sulfate salt. On the other hand, the dihydrogen phosphate salt was formed from orthophosphoric acid with PTH1, but the corresponding salt of PTH2 could not be crystallized and is likely to be a phosphate salt (see infrared spectra). Partial deprotonation of orthophosphoric acid yielded an unconventional dihydrogen phosphate cluster held by [HPTH1]+; similarly, partial deprotonation of sulfuric acid resulted in bisulfate−water assemblies stabilized by [HPTH2]+. A structural comparison on the nitrate-assisted assemblies of hydrated and anhydrous salts of PTH1 showed that the hydrated nitrate salt adopts cooperative cyclic hydrogenbonded structure with a syn−syn conformation of the host cation. Absence of water molecules in the nitrate salt 3.1a facilitated one nitrate to hold two host cations through cyclic hydrogen bonds, whereas there is another nitrate having hydrogen bonds with thiourea and nitrate anion. Thus, in the hydrated form of the nitrate salt, the water molecules competed and separated the two nitrate anions, which were found as pairs in the anhydrous form, possessing weak nitrate···nitrate interactions. This disruption made one of the nitrates bridge two host cations through bifurcated hydrogen bonds involving two oxygen atoms of nitrates with two independent acidic hydrogen atoms of two protonated methylthiazole units of two host cations as pivots. The other oxygen of the nitrate anion held another methylthiazole by N−H···O interaction. This causes the two nitro groups to be symmetry-independent. From thermochemical studies, it has been established that dehydration temperatures of the hydrated assemblies of the salts are governed by the environment provided by the cations and hydrated anions and also by the type of anion-assisted assemblies. Thus, the present study revealed that conformational polymorphs of similar energy with different orientations of the phenyl ring can be specifically crystallized from different solvents. The monomorphic nature of the positional isomer PTH2 arises from the tendency to form self-assembly of conformer locked through C−H···S interactions. Formation of hydrated anion assembly and deprotonation of a polyacid to form crystalline salt is host-specific. Dehydration of the hydrated salts occurs above or below the normal boiling point of water, depending on the type of hydrated anion as well as anion-assisted assemblies. Novel clusters of hydrated bromide ions, cyclic assemblies of dihydrogen phosphate, and chainlike structure of assemblies of bisulfate−water are established by stabilizing them in cationic hosts.

hydrogen-bond donors. The protons of these bonds form strong hydrogen bonds with dihydrogen phosphate ions. The two N−H bonds of thiourea are connected to the O3 atom of dihydrogen phosphate ion, whereas the N−H bond of the protonated 5-methylthiazole is connected through a hydrogen bond to another oxygen atom of a dihydrogen phosphate ion. The anions form a cyclic interanionic assembly with R22(8) and R66(24) motifs as shown in Figure 9b. These cyclic anionic assemblies form an extended polymeric structure, which looks like a planar sheet along the c-crystallographic axis (Figure S49, Supporting Information). Atom O1 interacts with N1−H and O2−H to form two hydrogen bonds (dD···A 2.63 and 2.47 Å and ∠D−H···A 166° and 177°, respectively). The hydrogen-bond acceptor atom O3 interacts with three N−H bonds, namely, N2−H and N3−H of thiourea and O4−H bonds of an anion, with D···A bond distances in the range 2.475−2.911 Å. Octameric29 and dimeric30,31 cyclic assemblies of dihydrogen phosphate anions were reported earlier. In the present case, we have observed hydrogen-bonded cyclic hexameric assemblies of dihydrogen phosphate anions, which are held in the lattice by (HPTH1)+ ions. To the best of our knowledge, this is a new type of hexameric assembly of dihydrogen phosphate. We could not obtain a crystalline salt from the reaction of orthophosphoric acid with PTH2, but we did obtain a white precipitate from the reaction of phosphoric acid with PTH2. Salt 6a, which is derived from PTH1, shows sharp P−O stretching at 988 and 1096 cm−1 from the dihydrogen phosphate anion,32 and there is an overtone of O−H bending vibration at 2400 cm−1 due to the anion. In contrast to parent compound PTH1, which has very broad and sharp N−H stretch at 3400 cm−1, tphosphate salt 6a has very broad less resolved absorptions spreading from 2500 to 3500 cm−1. The white solid obtained from the reaction of PTH2 with phosphoric acid has broad and sharp N−H stretching at 3430 cm−1, which is similar to the N−H stretching of parent PTH2 occurring at 3327 cm−1. In addition to this, the IR spectrum is relatively simple and has a sharp P−O stretching frequency at 965 cm−1 (Figure S50, Supporting Information), suggesting that the anhydrous phosphate salt was formed in this case. Low solubilty of this salt in common solvents made it difficult to characterize further. Generally, symmetric thiourea derivatives show syn−syn conformation;33a−c however, syn−anti conformation is encountered in solvates under special circumstances.33d The latter observation is a clear indication that solvent can enforce conformational changes through modification of self-assembly. From the results obtained by us, it is clear that the different orientations of the phenyl group of PTH1 could be achieved through change of solvent in the crystallization process. None of the polymorphs reported here is metastable, hence the interplay of weak interactions of solute and solvent guided the crystallization of the three polymorphs of PTH1 with different orientations of the phenyl ring. On the other hand, the intramolecular hydrogen bonds in PTH1 or PTH2 guided them to adopt a syn−anti arrangement in each case. In the structure of each salt, the intramolecular hydrogen bond is absent; as a consequence they adopt the syn−syn conformation. Anhydrous chloride salts of PTH1 or PTH2 possess bifurcated hydrogen bonds, with the chloride ion as pivot connected to two N−H bonds of thiourea. We find that the chloride and bromide salts have large differences in compositions and self-assembly. The bromide salt of PTH1 is a one-dimensional polymeric chain, while PTH2 provided a platform for stabilization of a bromide−water cluster. The

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EXPERIMENTAL SECTION

All reagents were purchased from Sigma−Aldrich and used as received. IR spectra were recorded on a PerkinElmer Spectrum One FT-IR spectrometer with KBr pellets in the range 4000−400 cm−1. The 1H NMR spectra were recorded on a Varian 400 MHz FT-NMR spectrometer with tetramethylsilane (TMS) as internal standard. 2648



Article 1

PXRD patterns were recorded on a Bruker D8 Advance (Germany) diffractometer with Cu Kα (1.542 Å) radiation, operating at 40 kV and 40 mA on a glass surface of air-dried samples. Thermogravimetric analyses were performed on a TA Instruments SDT Q600 thermogravimetric analyzer under nitrogen atmosphere with 5 °C heating rate. Differential scanning calorimetry plots were recorded by use of a TA Instrument Q20 differential scanning calorimeter and SDT Q600 analyzer under nitrogen atmosphere. Calibration of the instrument was performed with indium standard with cell constant 1.0609, and the experimental accuracy of temperature was ±0.1 °C. Synthesis of 1-(5-Methylthiazol-2-yl)-3-phenylthiourea (PTH1). 5-Methylthiazol-2-ylamine (57 mg, 5 mmol) and phenyl isothiocyanate (67 mg, 5 mmol) were dissolved in dry dichloromethane (20 mL), and the solution was stirred for 6 h by placing the reaction vessel in an ice bath. The resulting solution was evaporated, and the precipitate was dried in vacuum. Yield 90%. 1H NMR (400 MHz, CDCl3) 7.58 (d, J = 10.0 Hz, 2H), 7.37 (t, J = 9.6 Hz, 2H), 7.25 (t, 1H), 6.96 (s, 1H), 6.71 (s, 2H), 2.26 (s, 3H). ESI MS 250.7944 [M + 1]. IR (cm−1) 3440 (w), 3175 (m), 3022 (m), 2918 (m), 1627 (s), 1574 (s), 1536 (s), 1496 (s), 1370 (m), 1258 (s), 1180 (s), 1127 (s), 1023 (s), 724 (s). Polymorph PTH1a was crystallized from tetrahydrofuran, whereas PTH1b and PTH1c were crystallized from methanol and N,N-dimethylformamide, respectively. Synthesis of 1-(4-Methylthiazol-2-yl)-3-phenylthiourea (PTH2). PTH2 was prepared by following a procedure similar to the synthesis of PTH1, but 4-methylthiazol-2-ylamine was used in place of 5-methylthiazol-2-ylamine. Crystals of PTH2 were obtained from its methanol solution. Yield 92%. 1H NMR (400 MHz, CDCl3) 7.60 (d, J = 7.2 Hz, 2H), 7.37 (t, J = 7.6 Hz, 1H), 7.24 (t, J = 7.2 Hz, 2H), 6.37 (s, 1H), 2.29 (s, 3H). ESI MS 250.0490 [M + 1]. IR (cm−1) 3433 (w), 3164 (m), 1594 (s), 1573 (s), 1531 (s), 1497 (s), 1372 (m), 1296 (s), 1260 (s), 1193 (s), 1132 (s), 731 (s), 686 (s), 648 (s), 486 (s). Synthesis of Salt (HPTH1)Cl (1a). Salt 1a was obtained by adding a few drops of hydrochloric acid (37%, 0.4 mL) to a solution of PTH1 (25 mg, 0.1 mmol) in methanol (5 mL). After addition of acid, the solution was stirred at room temperature for 30 min and filtered. The filtrate, upon standing under ambient conditions, yielded colorless crystals of 1a in 6−7 days. Yield 85%. 1H NMR (DMSO-d6, 400 MHz) 7.65 (d, J = 6.8 Hz, 2H) 7.42 (d, J = 7.6 Hz, 1H), 7.30 (t, J = 7.6 Hz, 2H), 7.21 (t, 2H), 7.04 (t, J = 7.2 Hz, 2H), 2.32 (s, 3H). IR (cm−1) 3052 (m), 1591 (s), 1560 (s), 1487 (s), 1409 (s), 1365 (m), 1317 (s), 1214 (s), 1183 (s), 819 (m), 757 (m), 688 (m). Salt (HPTH1)Br (2a). A similar procedure to that of 1a, but with addition of hydrobromic acid (37%, 0.4 mL) to a solution of PTH1 (124 mg, 0.5 mmol) in methanol (5 mL), resulted in colorless crystals of 1b after 1 week. Yield 82%. 1H NMR (CDCl3, 400 MHz) 10.38 (s, 2H), 7.61 (d, J = 7.6 Hz, 2H), 7.37 (t, J = 7.6 Hz, 2H), 7.26 (d, J = 6.0 Hz, 1H), 2.38 (s, 3H). IR (cm−1) 3434 (w), 1595 (s), 1561 (s), 1525 (s), 1495 (s), 1405 (s), 1321 (s), 1195 (s), 1100 (s), 755 (s), 685 (m), 513 (m). (HPTH1)2(NO3)2·H2O (3a) and (HPTH1)NO3 (3.1a). Solutions were made from PTH1 (124 mg, 0.5 mmol) and nitric acid (70%, 0.5 mL) in aqueous methanol (10% in water, 10 mL) as well as in dry methanol (10 mL), and the two solutions were left for crystallization. Colorless crystals of 3a and light yellow crystals of 3.1a were formed after 1 week. Yield 85%. 1H NMR (DMSO-d6, 400 MHz) 10.26 (s, 2H), 7.69 (d, J = 7.6 Hz, 2H), 7.26 (t, J = 7.6 Hz, 2H), 7.12 (s, 1H), 7.05 (t, 1H), 2.07 (s, 3H). IR (cm−1) 3434 (w), 1766 (m), 1626 (m), 1384 (s), 1020 (m) 827 (m). (HPTH1)ClO4·2H2O (4a). Equimolar amounts of PTH1 (124 mg, 0.5 mmol) and perchloric acid (60%, 0.4 mL) were dissolved in methanol (10 mL), and the solution was left for crystallization. Colorless crystals were formed after 1 week. Yield 93%. 1H NMR (DMSO-d6, 400 MHz) 7.12 (s, 1H), 7.59 (d, J = 5.6 Hz, 2H), 7.47 (s, 1H), 7.41 (t, J = 7.2 Hz, 2H), 7.24 (t, J = 7.0 Hz, 2H), 2.39 (s, 3H). IR (cm−1) 3056 (m), 1591 (s), 1553 (s), 1496 (s), 1319 (s), 1216 (s), 1140 (m), 753 (s), 626 (s). (HPTH1)2SO4 (5a). PTH1 (249 mg, 1 mmol) and sulfuric acid (95%, 0.3 mL) were dissolved in methanol (15 mL) and kept for crystallization. Colorless crystals were formed after 1 week. Yield 96%.

H NMR (DMSO-d6, 400 MHz) 9.09 (s, 1H), 7.68 (d, J = 8.8 Hz, 2H), 7.28 (t, J = 7.6 Hz, 2H), 7.12 (s, 1H), 7.05 (t, J = 7.0 Hz, 1H), 2.26 (s, 3H). IR (cm−1) 2986 (m), 1607 (s), 1564 (s), 1531 (s), 1497 (s), 1322 (s), 1197 (s), 1038 (m), 761 (s), 605 (s). (HPTH1)H2PO4 (6a). PTH1 (25 mg, 0.1 mmol) was suspended in methanol (10 mL), and a drop of orthophosphoric acid (0.2 mL) was added. After the mixture was stirred for 30 min, a clear solution formed, which on standing resulted in block-shaped crystals after 1 week. Yield 82%. 1H NMR (DMSO-d6, 400 MHz) 7.69 (d, J = 8.0 Hz, 2H), 7.46 (d, J = 7.2 Hz, 2H), 7.26 (t, J = 7.6 Hz, 2H), 7.06 (s, 1H), 7.02 (t, J = 8.0 Hz, 1H), 2.25 (s, 3H). IR (cm−1) 3321 (m), 1596 (s), 1552 (s), 1496 (s), 1370 (s), 1321 (s), 1190 (s), 1096 (s), 988 (s), 891 (m), 813 (m), 710 (m), 651 (m), 501 (m). (HPTH2)Cl (1b). Salt 1b was obtained by adding hydrochloric acid (37%, 0.4 mL) to methanol (5 mL) solution of PTH2 (25 mg, 0.1 mmol). From this solution, colorless crystals were obtained after a week. Yield 88%. 1H NMR (DMSO-d6, 400 MHz) 9.70 (s, 2H), 7.46 (d, J = 4.4 Hz, 2H), 7.30 (t, J = 7.2 Hz, 2H), 7.04 (t, J = 6.8 Hz, 1H), 6.80 (s, 1H), 2.35 (s, 3H). IR (cm−1) 2663 (w), 1590 (s), 1559 (s), 1494 (s), 1417 (s), 1353 (s), 11.87 (s), 841 (m), 688 (m), 659 (m). (PTH2)2(Br)2·6H2O (2b). Salt 2b was obtained by adding hydrobromic acid (37%, 0.4 mL) to methanol (5 mL) solution of PTH2 (124 mg, 0.5 mmol). The solution was allowed to evaporate at room temperature, which yielded colorless crystals in 6−7 days. Yield 92%. 1H NMR (DMSO-d6, 400 MHz) 9.20 (s, 2H), 7.47 (d, J = 7.6 Hz, 2H), 7.33 (t, J = 7.2 Hz, 2H), 7.03 (t, J = 7.2 Hz, 1H), 6.70 (s, 1H), 2.32 (s, 3H). IR (cm−1) 3381 (w), 3297 (m), 3067 (m), 1594 (s), 1561 (s), 1496 (s), 1420 (s), 1360 (s), 1323 (s), 1216 (s), 1190 (s), 757 (s), 719 (m), 686 (m), 654 (m). (HPTH2)NO3 (3b). A solution prepared from PTH2 (124 mg, 0.5 mmol) and nitric acid (70%, 0.4 mL) gave colorless crystals after 1 week. Yield 95%. 1H NMR (DMSO-d6, 400 MHz) 7.69 (d, J = 7.6 Hz, 2H), 7.27 (t, J = 4.8 Hz, 2H), 7.13 (s, 2H), 7.06 (t, J = 7.6 Hz, 1H), 6.50 (s, 1H), 2.21 (s, 3H). IR (cm−1) 3432 (w), 1620 (m), 1546 (m), 1499 (m), 1205 (w), 1121 (w), 757 (m). (HPTH2)ClO4·H2O (4b). PTH2 (124 mg, 0.5 mmol) and perchloric acid (60%, 0.5 mL) were dissolved in methanol (10 mL), and the solution was left for crystallization. Colorless crystals were formed after 3 days. Yield 96%. 1H NMR (DMSO-d6, 400 MHz) 7.61 (d, J = 7.0 Hz, 2H), 7.44 (d, J = 8.0 Hz, 2H), 7.32 (t, J = 6.8 Hz, 2H), 7.23 (s, 1H), 7.06 (t, J = 7.0 Hz, 2H), 2.32 (s, 3H). IR (cm−1) 3397 (w), 1594 (s), 1561 (s), 1496 (m), 1419 (m), 1360 (m), 1323 (s), 1144 (m), 1112 (m), 626 (s). (HPTH2)HSO4·H2O (5b). Salt 5b was obtained by adding sulfuric acid (95%, 0.2 mL) to methanol (5 mL) solution of PTH2 (25 mg, 0.1 mmol). Colorless crystals were formed in 6−7 days. Yield 73%. 1H NMR (DMSO-d6, 400 MHz) 7.69 (d, J = 8.4 Hz, 2H), 7.28 (t, J = 3.6 Hz, 2H), 7.04 (t, J = 7.2 Hz, 1H), 6.53 (s, 1H), 2.21 (s, 3H). IR (cm−1) 1327 (w), 3082 (m), 1624 (m), 1594 (s), 1559 (s), 1497 (s), 1358 (s), 1317 (s), 1234 (s), 1133 (s), 1046 (m), 762 (m), 692 (m). X-ray Crystallography. Single-crystal X-ray diffraction data for PTH1a−c, PTH2, 1b, 3a, 3b, and 6a were collected at 296 K with Mo Kα radiation (λ = 0.710 73 Å) with the use of a Bruker Nonius SMART APEX charge-coupled device (CCD) diffractometer equipped with a graphite monochromator and an Apex CCD camera, whereas for 2a, 3.1a, 4a, 5a, 2b, 4b, and 5b, the X-ray diffraction data were collected on an Oxford SuperNova diffractometer. SMART was used for data collection and also for indexing the reflections and determining the unit cell parameters. Data reduction and cell refinement were performed with SAINT software.34 For data collected on the SuperNova diffractometer, data refinement and cell reductions were carried out by CrysAlisPro.35 The structures were solved by direct methods and refined by full-matrix least-squares calculations with SHELXTL.34 All non-hydrogen atoms were refined in the anisotropic approximation against F2 of all reflections. Hydrogen atoms attached to the heteroatoms were freely allowed to ride in the difference Fourier synthesis maps and were refined with isotropic displacement coefficients. Crystallographic parameters are summarized in Table 2. 2649



Article

Table 2. Crystallographic Parameters of PTH1 Polymorphs, PTH2, and Their Salts formula mol wt crystal system space group temp, K wavelength, Å a, Å b, Å c, Å α, deg β, deg γ, deg V, Å3 Z density, g·cm−3 abs coeff, mm−1 abs correction F(000) total reflns reflns, I > 2σ(I) max θ, deg h range k range l range complete to 2θ, % data/restrain/param goof, F2 R indices, I > 2σ(I) R indices, all data formula mol wt crystal system space group temp, K wavelength, Å a, Å b, Å c, Å α, deg β, deg γ, deg V, Å3 Z density, g·cm−3 abs coeff, mm−1 abs correction F(000) total reflns reflns, I > 2σ(I) max θ, deg h range k range l range complete to 2θ, % data/restrain/param goof, F2 R indices, I > 2σ(I) R indices, all data

PTH1a

PTH1b

PTH1c

PTH2

C11H11N3S2 249.35 monoclinic P21/c 296(2) 0.710 73 11.3183(4) 5.7063(2) 20.5287(6) 90.00 113.537(2) 90.00 1215.55(7) 4 1.363 0.413 multiscan 520 2225 1791 25.50 −13 ≤ h ≤ 12 −6 ≤ k ≤ 6 −23 ≤ l ≤ 23 98.2 2225/0/178 1.080 0.0371 0.0439 1a

C11H11N3S2 249.35 triclinic P1̅ 296(2) 0.710 73 8.941(3) 10.074(3) 13.822(4) 92.594(18) 95.21(2) 105.985(17) 1188.7(6) 4 1.393 0.423 multiscan 520 4111 2239 25.00 −8 ≤ h ≤ 9 −11 ≤ k ≤ 11 −16 ≤ l ≤ 15 98.1 4111/0/291 1.087 0.0480 0.0822 2a

C11H11N3S2 249.35 monoclinic C2/c 296(2) 0.710 73 16.8654(10) 6.1269(3) 24.5611(14) 90.00 108.596(7) 90.00 2405.5(2) 8 1.377 0.418 multiscan 1040 2174 1564 25.24 −20 ≤ h ≤ 18 −7 ≤ k ≤ 7 −28 ≤ l ≤ 29 1.00 2174/0/146 1.040 0.0375 0.0610 3a

C11H11N3S2 249.35 triclinic P1̅ 296(2) 0.710 73 5.7601(7) 8.8710(10) 12.0970(14) 103.779(6) 96.286(6) 95.705(6) 591.67(12) 2 1.400 0.425 multiscan 260 2111 1300 25.25 −6 ≤ h ≤ 6 −10 ≤ k ≤ 10 −14 ≤ l ≤ 14 98.4 2111/0/178 1.022 0.0511 0.1027 3.1a

C11 H12 Br N3 S2 330.28 monoclinic I2/c 296(2) 0.710 73 23.7103(11) 4.45641(17) 25.3321(7) 90.00 95.947(3) 90.00 2662.26(17) 8 1.648 3.383 multiscan 1328 2410 1855 25.24 −28 ≤ h ≤ 22 −4 ≤ k ≤ 5 −22 ≤ l ≤ 30 99.8 2410/5/191 1.020 0.0358 0.0540

C22 H26 N8 O7 S4 642.79 triclinic P1̅ 296(2) 0.710 73 10.551(3) 10.6973(19) 13.648(3) 108.804(9) 96.519(11) 91.481(8) 1445.6(5) 2 1.477 0.385 multiscan 668 5155 3214 25.25 −12 ≤ h ≤ 10 −12 ≤ k ≤ 12 −16 ≤ l ≤ 16 98.2 5155/0/452 1.053 0.0459 0.0789

C11 H12 Cl N3 S2 285.81 triclinic P1̅ 296(2) 0.710 73 9.6400 (6) 15.4273 (9) 19.1760 (11) 73.592 (5) 86.432(5) 89.798(5) 2730.1(3) 8 1.391 0.567 none 1184.0 9999 6880 25.50 −8 ≤ h ≤ 11 −18 ≤ k ≤ 18 −22 ≤ l ≤ 23 98.2 9999/0/761 0.995 0.0451 0.0712

2650

C11 H12 N4 O3 S2 312.39 monoclinic P21/n 296(2) 0.710 73 19.502(3) 6.1168(7) 23.967(3) 90.00 105.989(16) 90.00 2748.5(6) 8 1.510 0.400 multiscan 1296 4839 2483 25.00 −23 ≤ h ≤ 23 −6 ≤ k ≤ 7 −15 ≤ l ≤ 28 99.9 4839/0/363 1.213 0.0859 0.1640



Article

Table 2. continued formula mol wt crystal system space group temp, K wavelength, Å a, Å b, Å c, Å α, deg β, deg γ, deg V, Å3 Z density, g·cm−3 abs coeff, mm−1 abs correction F(000) total reflns reflns, I > 2σ(I) max θ, deg h range k range l range complete to 2θ, % data/restrain/param goof, F2 R indices, I > 2σ(I) R indices, all data formula mol wt crystal system space group temp, K wavelength, Å a, Å b, Å c, Å α, deg β, deg γ, deg V, Å3 Z density, g·cm−3 abs coeff, mm−1 abs correction F(000) total reflns reflns, I > 2σ(I) max θ, deg h range k range l range complete to 2θ, % data/restrain/param goof, F2 R indices, I > 2σ(I) R indices, all data

4a

5a

6a

1b

C11H16 Cl N3O6S2 385.86 monoclinic P21/a 296(2) 0.710 73 14.6126(4) 7.3778(2) 15.9027(4) 90.00 95.712(2) 90.00 1705.94(8) 4 1.502 0.500 multiscan 800 3078 2501 25.25 −15 ≤ h ≤ 17 −7 ≤ k ≤ 8 −18 ≤ l ≤ 19 99.9 3078/17/253 1.068 0.0698 0.0747 2b

C22 H24N6O4 S5 596.82 triclinic P1̅ 296(2) 0.710 73 11.1939(13) 11.8157(16) 12.0646(17) 110.959(13) 106.648(11) 104.205(11) 1315.3(3) 2 1.507 0.483 multiscan 620.0 4767 3061 25.25 −13 ≤ h ≤ 12 −14 ≤ k ≤ 14 −14 ≤ l ≤ 13 99.8 4767/0/400 1.019 0.0601 0.0927 3b

C11H14N3O4PS2 347.34 monoclinic C2/c 296(2) 0.710 73 11.6810(19) 8.5182(19) 30.608(6) 90.00 100.777(13) 90.00 2991.8(10) 8 1.542 0.481 multiscan 1440 2666 1434 25.24 −9 ≤ h ≤ 14 −8 ≤ k ≤ 10 −35 ≤ l ≤36 98.4 2666/5/208 1.012 0.0469 0.0812 4b

C11 H12Cl N3S2 285.81 triclinic P1̅ 296(2) 0.710 73 8.6544(9) 9.2851(9) 10.0278(12) 65.682(5) 75.992(5) 64.045(4) 658.36(12) 2 1.442 0.588 multiscan 296 2299 1625 25.00 −9 ≤ h ≤ 10 −10 ≤ k ≤ 10 −11 ≤ l ≤ 10 99.2 2299/0/155 1.079 0.0330 0.0405 5b

C11 H18 BrN3O3S2 384.31 monoclinic P21/n 296(2) 0.710 73 14.3819(10) 7.2911(4) 31.790(2) 90.00 94.778(6) 90.00 3321.9(4) 8 1.537 2.735 multiscan 1568 6180 3744 25.50 −15 ≤ h ≤ 17 −8 ≤ k ≤ 8 −24 ≤ l ≤ 38 99.9 6180/12/411 0.959 0.0587 0.1564

C11 H12 N4O3S2 312.39 monoclinic P21/n 296(2) 0.710 73 11.2755(8) 18.3129(14) 14.0015(10) 90.00 103.005(4) 90.00 2817.0(4) 8 1.473 0.390 multiscan 1296 4899 2500 25.00 −13 ≤ h ≤ 11 −21 ≤ k ≤ 20 −16 ≤ l ≤16 98.4 4899/7/435 0.994 0.0557 0.1479

2651

C11 H14 Cl N3O5 S2 367.84 triclinic P1̅ 296(2) 0.710 73 7.5147(5) 9.0185(8) 12.1146(7) 90.801(6) 98.642(5) 109.424(7) 763.70(10) 2 1.600 0.550 multiscan 380.0 2752 1948 25.25 −9 ≤ h ≤ 8 −10 ≤ k ≤ 10 −14 ≤ l ≤14 99.8 2752/12/240 1. 008 0.0535 0.0792

C11 H15 N3O5S3 365.47 triclinic P1̅ 296(2) 0.710 73 7.0435(5) 9.4168(9) 12.3566(10) 85.815(7) 88.897(7) 71.023(8) 772.96(11) 2 1.570 0.505 multiscan 380.0 2801 2029 25.24 −8 ≤ h ≤ 8 −11 ≤ k ≤ 11 −14 ≤ l ≤14 99.9 2801/0/236 1.024 0.0604 0.0798



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ASSOCIATED CONTENT

S Supporting Information *

One table with hydrogen-bond parameters for all salts and 54 figures with PXRD patterns of all compounds, spectroscopic data and differential scanning calorimetry of the three polymorphs, and thermogravimetric analysis and differential scanning calorimetry of hydrated salts. Crystallographic information files of polymorphs of PTH1, PTH2, and salts. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Fax +91-361-2690762; phone +91-361-2582311; e-mail [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS N.P. is thankful to the Council of Scientific and Industrial Research, New Delhi, India, for a senior research fellowship.

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REFERENCES

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Polymorphs of 1-(5-Methylthiazol-2-yl)-3 ... - ACS Publications

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