Salt and co-crystal formation from 2-(imidazol-1-yl)-1-phenylethanone and different acidic components

Article abstract of DOI:10.1016/j.molstruc.2011.08.058

Four crystalline adducts derived from 2-(imidazol-1-yl)-1-phenylethanone and the acidic compounds (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, and 5-nitrosalicylic acid) were prepared and characterized by X-ray diffraction analysis, in

Full text of DOI:10.1016/j.molstruc.2011.08.058

Journal of Molecular Structure 1006 (2011) 128–135
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Salt and co-crystal formation from 2-(imidazol-1-yl)-1-phenylethanone
and different acidic components
b
c
a
Shouwen Jin a, , Ming Guo , Daqi Wang , Han Cui
⇑
a Tianmu College of ZheJiang A & F University, Lin’An 311300, PR China
b Graduate Department ZheJiang A & F University, Lin’An 311300, PR China
c Department of Chemistry, Liaocheng University, Liaocheng 252059, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 June 2011
Received in revised form 30 August 2011
Accepted 30 August 2011
Available online 7 September 2011
Four crystalline adducts derived from 2-(imidazol-1-yl)-1-phenylethanone and the acidic compounds
(2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, and 5-nitrosalicylic acid) were prepared
and characterized by X-ray diffraction analysis, infrared spectrum, melting point, and elemental analysis.
All supramolecular architectures of 1–4 involve extensive classical hydrogen bonds as well as other non-
covalent interactions. The results presented herein indicate that the strength and directionality of the
NAHꢀ ꢀ ꢀO, OAHꢀ ꢀ ꢀN, and OAHꢀ ꢀ ꢀO hydrogen bonds (ionic or neutral) between acidic components and
2-(imidazol-1-yl)-1-phenylethanone are sufficient to bring about the formation of binary organic acid–
base adducts.
Keywords:
Crystal structure
Hydrogen bonds
Secondary interactions
2-(Imidazol-1-yl)-1-phenylethanone
Acidic components
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
most frequently used moieties with hydrogen bonding capability
are pyridyl and carboxyl. Recently, another building block that
Supramolecular interactions have attracted considerable atten-
tion during the past few years because the utilization of intermo-
lecular noncovalent interactions is relied upon for the design and
development of functional materials [1]. Noncovalent interactions
form the backbone of supramolecular chemistry and include
classical/nonclassical hydrogen bond, stacking, electrostatic,
hydrophobic and charge-transfer interactions [2]. Of these inter-
actions hydrogen bond interactions are well-established supra-
molecular interactions and there have been many reported
topology structures assembled through hydrogen bonds, such as
an infinite 1-D chain [3], 1-D tapes [4], 2D sheet [5], and 3-D net-
works [6].
Because of the predictable supramolecular properties and the
ability to form strong hydrogen bonds, carboxylic acids were fre-
quently chosen as building blocks for crystal engineering [7–9].
Numerous heterodimers composed of carboxylic acids and a vari-
ety of N-containing basic building blocks have been documented
recently [10–14]. Hydrogen bonding between hydroxyl groups of
carboxylic acids and heterocyclic nitrogen atoms has been proved
to be a useful and powerful organizing force for the formation of
supramolecules. It should be noted that these structures are nor-
mally held together by hydrogen bonding, and in this regard, the
has become quite popular is imidazole or its derivatives, owing
to their assembling capacity via acid–base recognition with a large
number of molecules possessing acidic sites, especially carboxylic
acids [15–27].
In addition to an imidazole group, 2-(imidazol-1-yl)-1-phenyl-
ethanone bears a C@O group and a benzene ring. The carbonyl
group is a good acceptor in forming noncovalent interactions,
and the benzene moiety may give aromatic stacking interactions,
thus carrying out the binary adducts between the acidic com-
pounds and 2-(imidazol-1-yl)-1-phenylethanone may display
the different non-bonding ability of the three different functional
groups. Following our previous works of acid–base adducts based
on imidazole derivatives and carboxylic acids [28–30], we herein
report the synthesis and crystal structure of four supramolecular
assemblies assembled through hydrogen bonding interactions
between acidic tectons and 2-(imidazol-1-yl)-1-phenylethanone.
In this study, we obtained four organic acid–base adducts
composed of acidic units and 2-(imidazol-1-yl)-1-phenylethanone
(Scheme 1), namely 2-(imidazol-1-yl)-1-phenylethanone: (2,4,6-
trinitrophenol) (1) [(HL)+ ꢀ (picꢁ), picꢁ = picrate, L = 2-(imidazol-
1-yl)-1-phenylethanone],
2-(imidazol-1-yl)-1-phenylethanone:
(p-nitrobenzoic acid) (2) [(HL)+ ꢀ (L) ꢀ (Hnba) ꢀ (nba)ꢁ, Hnba =
p-nitrobenz oic acid], 2-(imidazol-1-yl)-1-phenylethanone: (m-
nitrobenzoic acid) (3) [(L ꢀ Hmba), Hmba = m-nitrobenzoic acid],
and 2-(imidazol-1-yl)-1-phenylethanone: (5-nitrosalicylic acid)
(4) [(HL) ꢀ (5-nsaꢁ), 5-nsaꢁ = 5-nitrosalicylate].
⇑
Corresponding author. Tel./fax: +86 571 6374 6755.
E-mail address: jinsw@zafu.edu.cn (S. Jin).
0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2011.08.058

S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
129
2.2.2. 2-(imidazol-1-yl)-1-phenylethanone: (p-nitrobenzoic acid)
OH
[(HL)+ ꢀ (L) ꢀ (Hnba) ꢀ (nbaꢁ), Hnba = p-nitrobenzoic acid] (2)
O2N
NO2
2-(imidazol-1-yl)-1-phenylethanone
(18.6 mg,
0.10 mmol)
O
dissolved in 1 mL ethanol. To this solution, p-nitrobenzoic acid
(16.7 g, 0.1 mmol) in 6 mL of methanol was added. Colorless crystals
were obtained after several days of slow evaporation of the solvent,
yield: 27 mg, 76.42% (based on L). mp 198–199 °C. Elemental anal-
ysis: Calc. for C36H30N6O10: C, 61.13; H, 4.24; N, 11.88. Found: C,
61.12; H, 4.18; N, 11.82. Infrared spectrum (cmꢁ1): 3456s(multiple,
NO2
HO
NO2
2,4,6-trinitrophenol
O
p-nitrobenzoic acid
HO
m
as(NH)), 3223s(
2718m, 2498w, 2374m, 2213m, 1976w, 1902w, 1836w, 1783w,
1718s( (C@O)), 1644vs( (C@O)), 1606s(
as(COOꢁ)), 1578m, 1533s
as(NO2)), 1466w, 1374s( s(NO2)), 1280s
s(COOꢁ)), 1328s(
(CAO)), 1250m, 1195m, 1150w, 1102w, 1069m, 952m, 903m,
ms(NH)), 3146m, 3064m, 2960m, 2842m,
m
m
m
(
(
m
m
m
m
NO2
856m, 806m, 757m, 726m, 680m, 627m, 572m.
HO
HO
NO2
2.2.3. 2-(imidazol-1-yl)-1-phenylethanone: (m-nitrobenzoic acid)
[(L ꢀ Hmba), Hmba = m-nitrobenzoic acid] (3)
O
2-(imidazol-1-yl)-1-phenylethanone (18.6 mg, 0.10 mmol) dis-
solved in 1 mL ethanol. To this solution, m-nitrobenzoic acid
(16.7 g, 0.10 mmol) in 5 mL of ethanol was added. Colorless
prisms were obtained after several days of slow evaporation of
the solvent, yield: 29 mg, 82.07% (based on L). mp 154–156 °C.
Elemental analysis: Calc. for C18H15N3O5: C, 61.13; H, 4.24; N,
11.88. Found: C, 61.08; H, 4.16; N, 11.83. Infrared spectrum
m-nitrobenzoic acid
5-nitrosalicylic acid
N
N
(cmꢁ1): 3666s(
2984s, 2918s, 2496m, 2388m, 2326m, 2082w, 1892m, 1763w,
1714s( (C@O)), 1668w, 1642s( (C@O)), 1620m, 1536s( as(NO2)),
1515m, 1486m, 1448m, 1320s( as(NO2)), 1282s( (CAO)), 1246m,
m(OH)), 3375s(mas(NH)), 3151s(ms(NH)), 3078m,
O
m
m
m
m
m
2-(imidazol-1-yl)-1-phenylethanone
1202m, 1162m, 1094m, 1006m, 952w, 877w, 831m, 797w,
724m, 654w, 618w, 525w.
Scheme 1.
2.2.4. 2-(imidazol-1-yl)-1-phenylethanone: (5-nitrosalicylic acid)
[(HL)+ ꢀ (5-nsaꢁ), 5-nsaꢁ = 5-nitrosalicylate] (4)
2. Experimental section
2-(imidazol-1-yl)-1-phenylethanone (18.6 mg, 0.10 mmol) dis-
solved in 1 mL ethanol. To this solution, 5-nitrosalicylic acid
(18.3 mg, 0.1 mmol) in 4 mL of ethanol was added. Red prisms
were obtained after several days of slow evaporation of the solvent,
yield: 29 mg, 78.52% (based on L). mp 186–188 °C. Elemental anal-
ysis: Calc. for C18H15N3O6: C, 58.48; H, 4.06; N, 11.37. Found: C,
58.37; H, 3.96; N, 11.29. Infrared spectrum (cmꢁ1): 3574s
2.1. Materials and methods
2-(imidazol-1-yl)-1-phenylethanone (L) was prepared accord-
ing to a modified procedure of the literature [31]. All other re-
agents were commercially available and used as received. The C,
H, and N microanalysis were carried out with a Carlo Erba 1106
elemental analyzer. The FT-IR spectra were recorded from KBr pel-
lets in range 4000–400 cmꢁ1 on a Mattson Alpha-Centauri spec-
trometer. Melting points were recorded on an XT-4 thermal
apparatus without correction.
(
m
(OH)), 3486s(multiple,
2972m, 2846m, 2724m, 2432w, 2386m, 2231m, 1996w, 1868w,
1783w, 1692s, 1640s( (C@O)), 1612m, 1592s(
as(COOꢁ)),
as(NO2)), 1521m, 1454w, 1406s(
s(COOꢁ)), 1358m,
s(NO2)), 1240m, 1142m, 1103m, 1074m, 1020m, 946m,
mas(NH)), 3338s(ms(NH)), 3115m, 3054m,
m
m
1540s(
1314s(
m
m
m
868m, 806m, 757m, 680m, 604m, 558m.
2.2. Preparation of compounds 1–4
2.2.1. 2-(imidazol-1-yl)-1-phenylethanone: (2,4,6-trinitrophenol)
[(HL)+ ꢀ (picꢁ), picꢁ = picrate, L = 2-(imidazol-1-yl)-1-phenylethanone],
(1)
2.3. X-ray crystallography
The X-ray intensity data were measured on a Bruker SMART
2-(imidazol-1-yl)-1-phenylethanone (18.6 mg, 0.10 mmol) was
dissolved in 3 mL methanol. To this solution, 2,4,6-trinitrophenol
(23 mg, 0.1 mmol) in 10 ml of methanol was added. Yellow block
crystals were obtained after several days by slow evaporation of
the solvent (yield: 33 mg, 79.46%). mp 222–224 °C. Elemental anal-
ysis: Calc. for C17H13N5O8: C, 49.12; H, 3.13; N, 16.85. Found: C,
1000 CCD diffractometer using Mo Ka radiation (k = 0.71073 Å).
Data collections and reductions were performed using the SMART
and SAINT software [32, 33]. The structures were solved by direct
methods, and the non-hydrogen atoms were subjected to aniso-
tropic refinement by full-matrix least squares on F2 using the
SHELXTL package [34]. In the absence of significant anomalous
scattering, Friedel pairs in 4 have been merged before the final
refinement. Hydrogen atom positions for the four structures were
generated geometrically. Further details of the structural analysis
are summarized in Table 1. Selected bond lengths and angles for
compounds 1–4 are listed in Table 2; relevant hydrogen bond
parameters are provided in Table 3.
49.08; H, 3.06; N, 16.82. Infrared spectrum (cmꢁ1): 3440s(
3236s( s(NH)), 3194s, 3106s, 2968m, 2880m, 2826m, 2370m,
2322m, 1740m, 1697s, 1638vs( (C@O)), 1597m, 1525s( as(NO2)),
1480m, 1440m, 1400m, 1346m, 1324s( s(NO2)), 1260s, 1226m,
mas(NH)),
m
m
m
m
1156m, 1104w, 1080m, 1020m, 980m, 896m, 820m, 772m,
720m, 680m, 644m, 602m, 540m.

130
S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
Table 1
Summary of X-ray crystallographic data for compounds 1–4.
1
2
3
4
Formula
Fw
C
17H13N5O8
C36H30N6O10
706.66
C18H15N3O5
353.33
C18H15N3O6
369.33
415.32
T (K)
298(2)
298(2)
298(2)
298(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Monoclinic
C2/c
28.095(3)
5.1869(4)
25.903(2)
90
109.710(1)
90
3553.5(5)
8
1.553
0.126
1712
0.48 ꢂ 0.22 ꢂ 0.11
2.63–25.02
ꢁ27 6 h 6 32
ꢁ6 6 k 6 6
ꢁ30 6 l 6 30
8436
Triclinic
P1
Monoclinic
P21/c
19.3774(17)
12.0973(11)
7.1882(6)
90
92.062(1)
90
1683.9(3)
4
1.394
0.104
736
0.48 ꢂ 0.38 ꢂ 0.23
2.69–25.01
ꢁ14 6 h 6 22
ꢁ14 6 k 6 13
ꢁ8 6 l 6 7
8254
Orthorhombic
P212121
5.3029(5)
15.9360(14)
20.2249(19)
90
90
90
1709.1(3)
4
1.435
ꢀ
7.5314(6)
13.1318(12)
17.5069(16)
93.1150(1
102.197(2)
100.696(2)
1655.1(3)
2
1.418
0.106
736
0.46 ꢂ 0.45 ꢂ 0.42
2.39–25.02
ꢁ8 6 h 6 8
ꢁ15 6 k 6 14
ꢁ16 6 l 6 20
8617
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalcd (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
0.110
768
Crystal size (mm3)
h range (°)
0.50 ꢂ 0.38 ꢂ 0.36
2.39–25.02
ꢁ6 6 h 6 6
ꢁ18 6 k 6 18
ꢁ20 6 l 6 24
8659
Limiting indices
Reflections collected
Reflections independent (Rint
)
3121 (0.0542)
0.848
5734 (0.0316)
0.974
2974 (0.0815)
1.018
1777 (0.0567)
0.958
Goodness-of-fit on F2
R indices [I > 2
R indices (all data)
Largest diff. peak and hole (e Åꢁ3
r
I]
R1 = 0.0510
wR2 = 0.1339
0.296, ꢁ0.222
R1 = 0.0490
wR2 = 0.1456
0.171, ꢁ0.199
R1 = 0.0471
wR2 = 0.1223
0.193, ꢁ0.163
R1 = 0.0361
wR2 = 0.0915
0.108, ꢁ0.123
)
Table 2
Table 3
Selected bond lengths [Å] and angles [°] for 1–4.
Hydrogen bond distances and angles in studied structures 1–4.
1
DAHꢀ ꢀ ꢀA
1
d(DAH) [Å] d(Hꢀ ꢀ ꢀA) [Å] d(Dꢀ ꢀ ꢀA) [Å] <(DHA) [°]
N(1)AC(1)
N(1)AC(4)
N(2)AC(1)
O(2)AC(12)
C(1)AN(1)AC(4)
C(1)AN(2)AC(2)
1.315(3)
1.447(3)
1.305(3)
1.236(3)
125.9(3)
108.6(3)
N(1)AC(3)
O(1)AC(5)
N(2)AC(2)
C(1)AN(1)AC(3)
C(3)AN(1)AC(4)
N(2)AC(1)AN(1)
1.369(3)
1.213(3)
1.352(4)
108.1(2)
126.0(2)
109.1(3)
N(2)AH(2)ꢀ ꢀ ꢀO(2)#1 0.86
1.84
2.34
2.615(3)
2.985(4)
148.9
132.2
N(2)AH(2)ꢀ ꢀ ꢀO(3)#1 0.86
2
O(3)AH(3)ꢀ ꢀ ꢀN(2)#1 0.82
N(4)AH(4)ꢀ ꢀ ꢀO(7)#2 0.86
N(4)AH(4)ꢀ ꢀ ꢀO(8)#2 0.86
1.80
2.65
1.76
2.618(3)
3.113(3)
2.614(3)
172.5
115.3
170.0
2
N(1)AC(1)
N(1)AC(4)
N(2)AC(2)
N(3)AC(14)
N(4)AC(12)
O(1)AC(5)
O(3)AC(23)
O(7)AC(30)
C(1)AN(1)AC(3)
C(3)AN(1)AC(4)
C(12)AN(3)AC(14)
C(14)AN(3)AC(15)
N(2)AC(1)AN(1)
O(4)AC(23)AO(3)
1.346(3)
1.446(3)
1.376(4)
1.372(4)
1.310(3)
1.207(3)
1.132(3)
1.229(3)
106.5(2)
125.8(3)
107.6(2)
125.2(3)
112.0(3)
125.0(3)
N(1)AC(3)
N(2)AC(1)
N(3)AC(12)
N(3)AC(15)
N(4)AC(13)
O(2)AC(16)
O(4)AC(23)
O(8)AC(30)
C(1)AN(1)AC(4)
C(1)AN(2)AC(2)
C(12)AN(3)AC(15)
C(12)AN(4)AC(13)
N(4)AC(12)AN(3)
O(7)AC(30)AO(8)
1.377(4)
1.316(4)
1.340(3)
1.450(3)
1.365(4)
1.219(3)
1.216(3)
1.274(3)
127.6(3)
105.0(2)
127.2(3)
108.5(3)
109.2(3)
125.6(3)
3
O(2)AH(2)ꢀ ꢀ ꢀN(2)
4
0.82
1.73
2.552(3)
176.4
O(4)AH(4)ꢀ ꢀ ꢀO(2)
0.82
1.77
1.79
2.504(3)
2.652(3)
148.4
174.7
N(2)AH(2)ꢀ ꢀ ꢀO(3)#1 0.86
Symmetry transformations used to generate equivalent atoms for 1: #1 x, y ꢁ 1, z.
Symmetry transformations used to generate equivalent atoms for 2: #1 x, y + 1,
z + 1; #2 ꢁx + 1, ꢁy + 1, ꢁz. Symmetry transformations used to generate equivalent
atoms for 4: #1 ꢁx + 1, y ꢁ 1/2, ꢁz + 1/2.
3. Results and discussion
3
N(1)AC(1)
N(1)AC(4)
N(2)AC(2)
O(1)AC(5)
O(3)AC(12)
C(1)AN(1)AC(4)
C(1)AN(2)AC(2)
1.332(3)
1.452(3)
1.365(4)
1.210(3)
1.208(3)
126.2(2)
105.5(3)
N(1)AC(3)
N(2)AC(1)
N(3)AC(15)
O(2)AC(12)
C(1)AN(1)AC(3)
C(3)AN(1)AC(4)
N(2)AC(1)AN(1)
1.365(3)
1.314(3)
1.474(4)
1.301(3)
107.3(2)
126.4(2)
111.4(3)
3.1. Syntheses and general characterization
2-(imidazol-1-yl)-1-phenylethanone has good solubility in
common organic solvents, such as CH3OH, C2H5OH, CH3CN, CHCl3,
and CH2Cl2. For the preparation of 1–4, the acidic components
were mixed directly with the base in 1:1 ratio in methanol and/
or ethanol solvents, which was allowed to evaporate at ambient
conditions to give the final crystalline products. The molecular
structures and their atom labelling schemes for the four structures
are shown in Figs. 1, 3, 5 and 7, respectively.
The elemental analyses for all of the compounds are in good
agreement with their compositions. The infrared spectra of 1–4
are consistent with their chemical formulas determined by
elemental analysis and further confirmed by X-ray diffraction
4
N(1)AC(1)
N(1)AC(4)
N(2)AC(2)
N(3)AO(6)
O(1)AC(5)
O(3)AC(12)
C(1)AN(1)AC(3)
C(3)AN(1)AC(4)
N(1)AC(1)AN(2)
1.327(3)
1.457(3)
1.357(4)
1.229(3)
1.218(3)
1.241(3)
109.0(2)
125.9(2)
107.6(3)
N(1)AC(3)
N(2)AC(1)
N(3)AO(5)
N(3)AC(17)
O(2)AC(12)
O(4)AC(14)
C(1)AN(1)AC(4)
C(1)AN(2)AC(2)
O(3)AC(12)AO(2)
1.375(4)
1.328(3)
1.225(3)
1.468(4)
1.269(4)
1.345(3)
125.1(3)
109.3(3)
125.0(3)

S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
131
Fig. 1. The structure of 1, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
Fig. 2. The 1D chain formed via intrachain OAp, CHAO, and CH2AO interactions.
Fig. 3. The structure of 2, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
analysis. The very strong and broad features at 3600–3200 cmꢁ1
arise from OAH or NAH stretching frequencies. Benzene and imid-
azole ring stretching and bending are in the regions of 1500–
1630 cmꢁ1 and 600–750 cmꢁ1, respectively. The intense peak at
ca. 1640 cmꢁ1 was derived from the existence of the C@O stretches
in the cation.

132
S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
Fig. 4. A double chain structure of 2 when viewed down the a axis direction.
Fig. 5. The structure of 3, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
Fig. 6. 1D ladder running along the b axis direction.
All of the four adducts except compounds 1, and 3 show the
1:1 ratio. The asymmetric unit of 1 consists of one cation of 2-(imi-
dazolium-1-yl)-1-phenylethanone and one anion of picrate (Fig. 1).
This is a salt where the OH groups of 2,4,6-trinitrophenol are ion-
ized by proton transfer to the nitrogen atom (N(2)) of the 2-(imida-
zol-1-yl)-1-phenylethanone moieties, which is also confirmed by
the bond distance of O(2)AC(12) (1.236(3) Å) for phenolate
(1.24 0.01 Å) [38]. In the compound, there is one pair of ion pair
with no included solvent molecules. First of all, an examination of
the data in Table 2 shows that the distance value of C5AO1
(1.213 Å) in the cation clearly exhibits double-bond character.
Thus there is no keto-enol tautomerism which is due to the ab-
sence of strong intramolecular and intermolecular hydrogen bond-
ing that can produce a hydrogen bonded stable ring such as 5-, and
6-membered rings. This is also reflected by the bond of C4AC5
(1.509(4)) Å, which is a typical single bond. The O atom of the car-
bonyl group in the cation is at the trans position in respect to the H
at the NACHAN of the cation.
characteristic bands for COOꢁ, and compounds 2, and 3 display
strong IR peaks for COOH groups. The intense peak at ca.
1716 cmꢁ1 was derived from the existence of the C@O stretches,
and the band at ca. 1280 cmꢁ1 exhibited the presence of the CAO
stretches of the carboxyl group in 2, and 3. The presence of two
broad bands at ca. 2500 cmꢁ1 and 1900 cmꢁ1 in compounds 2,
and 3, characteristic of a neutral OAHꢀ ꢀ ꢀN hydrogen-bond interac-
tion, was viewed as evidence for co-crystal formation [35]. IR spec-
troscopy has also proven to be useful for the recognition of proton
transfer compounds [36]. The most distinct feature in the IR spec-
trum of proton transfer compounds is the presence of strong asym-
metrical and symmetrical carboxylate stretching frequencies at
1550–1610 cmꢁ1 and 1300–1420 cmꢁ1 in compounds 2, and 4,
respectively [37].
3.1.1. X-ray structure of 2-(imidazol-1-yl)-1-phenylethanone: (2,4,6-
trinitrophenol) [(HL)+ ꢀ (picꢁ)] (1)
In the solid state, there is consistently ionic hydrogen bond
formed between the imidazolium NH+ cation, and the 2,4,6-
trinitrophenolate anion.
Salt 1 was prepared by reacting of a methanol solution of
2,4,6-trinitrophenol and 2-(imidazol-1-yl)-1-phenylethanone in

S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
133
In this case the anions and the cations at the adjacent sheets were
slipped some distance from each other along the c axis direction. It
is worthy to point out that the third sheet has the same project on
the bc plane as the first sheet, so does the second sheet and the
fourth sheet.
3.1.2. X-ray structure of 2-(imidazol-1-yl)-1-phenylethanone: (p-nitro-
benzoic acid)[(HL)+ ꢀ L ꢀ Hnbd ꢀ (nbd)ꢁ] (2)
There are one protonated L, one molecule of L, one molecule of
p-nitrobenzoic acid, and one anion of p-nitrobenzoic acid in the
asymmetric unit of salt 2 (Fig. 3).
Similar to 1, the bond distances of C5AO1(1.207(3) Å) and
C16AO2 (1.219(3) Å) in the neutral L and in the cation clearly ex-
hibit typical double-bond characters. The CAO distances of the
COOH in the p-nitrobenzoic acid are ranging from 1.216(3)
[O(4)AC(23)] to 1.312(3) Å [O(3)AC(23)] with the
D value of
0.096 Å, which suggests that the carboxyl group is protonated.
While the CAO bond distances in the carboxylate group are
1.229(3) and 1.274(3) Å (
D is 0.045 Å) with the mean value of
1.251 Å which is shorter than the CAO single bond (1.312(3) Å)
and larger than the C@O double bond (1.216(3) Å). The O atoms
of the carbonyl groups in the cation and the neutral L are both at
the trans positions in respect to the corresponding Hs at the
NACHAN groups.
Fig. 7. The structure of 4, showing the atom-numbering scheme. Displacement
ellipsoids were drawn at the 30% probability level.
The ortho-nitro groups (N3AO3AO4, and N5AO7AO8) deviate
from the benzene plane and have dihedral angles of 9.3°, and
21.6° with the benzene plane, which are smaller than the corre-
sponding values of the reported salts based on picrates [39]. The
para-nitro group [N4AO5AO6] also deviates by 10.4° from the
benzene plane, which is larger than the corresponding data re-
ported by Muthamizhchelvan et al. [39]. The interplane angle be-
tween the benzene ring of the picrate and the imidazole ring is
8.5° indicating the coplanarity of both rings.
One L and one Hnbd form a heteroadduct (A) through the neu-
tral hydrogen bond (O(3)AH(3)ꢀ ꢀ ꢀN(2)#1, 2.618(3) Å). One HL+ cat-
ion and one nbdꢁ anion also formed a heteroadduct (B) through
two NAHꢀ ꢀ ꢀO hydrogen bonds with N-O distances of 2.614(3)
and 3.113(3) Å, and one CHAO association between 4-CH of the
imidazole cation and the carboxylate with CAO distance of
3.08 Å. For the presence of such interactions the anion and the cat-
ion generated close joint R12ð4Þ, and R12ð5Þ motifs. The heteroadduct
One anion is bound to one cation to generate a heteroadduct
through two N-Hꢀ ꢀ ꢀO hydrogen bonds with NAO distance of
2.615(3)–2.985(4) Å. Of the two NAHꢀ ꢀ ꢀO hydrogen bonds one is
between the NH+ and the phenolate group, the other is between
the NH+ group and the para-NO2 group. Under the bifurcated
hydrogen bonding interactions the anion and the cation made a
R21ð6Þ ring motif according to Bernstein [40].
(A) and heteroadduct (B) were connected together via CHA
p and
CHAO interactions to form a tetra-component adduct. The adjacent
tetra-component adducts were combined together by the CHAO
interaction between the benzene CH of the cation and the nitro
group with CAO distance of 3.31 Å, and 3.57 Å respectively to form
a 1D chain running along the b axis direction. Two such parallel
chains were joined together via the CHAO interaction between
the NACHAN and the carboxylate with CAO distance of 3.42 Å,
Such heteroadducts were held together via the OA
p (between
the O atom of the nitro group and the benzene ring of the anion
with OACg distance of 3.16 Å), CHAO (between NACHAN of the
cation and the carbonyl group of its neighboring cation with
CAO distance of 3.42 Å), and CH2AO interactions (between CH2
of the cation and the C@O of its neighboring cation with CAO dis-
tance of 3.31 Å). In this case the OACg distance is comparable to
the archived data (3.12 Å) [41]. For the presence of such kind of
interactions two cations generated a R12ð6Þ graph set.
and CHAp interaction between the benzene CH of the anion and
the benzene ring of the cation with CACg distance of 3.67 Å to form
a double chain (Fig. 4). The double chains were arranged parallelly
on the bc plane, but there are no connections between them. The
double chains were stacked along the a axis direction via the
CHAO, CHAp, and CH2AO interactions to form a 3D network struc-
ture. Here the adjacent double chains were slipped some distance
from each other along the c axis direction such that one double
chain of the first layer is connected with two double chains of
the second layer.
Through these interactions the heteroadducts were connected
together to form a 1D chain (A) running along the b axis direction
(Fig. 2). There are also 1D chain (B) running along the b axis direc-
tion composed of the above heteroadducts, yet the cations on the
(B) chain were antiparallel to the cations at the (A) chain, and
the anions on the (B) chain formed an angle of ca. 82° with the an-
ions on the (A) chain. The A chains and the B chains were joined
together by the interchain CHAO interactions between the ben-
zene CH of the cation and the para-nitro group with CAO distance
of 3.54 Å, and CHAC(carbonyl) interaction between the benzene
CH of the cation and the C@O group of the neighboring chain with
CAC distance of 3.55 Å to form a double chain extending along the
b axis direction. The double chains were further linked together via
the CHAO interaction between the benzene CH of the anion and
the o-nitro group with CAO distance of 3.20 Å along the c axis
direction to form a 2D sheet extending on the bc plane. The sheets
were further stacked along the a axis direction by the intersheet
CHAO, and CH2AO interactions to form a 3D network structure.
3.1.3. X-ray structure of 2-(imidazol-1-yl)-1-phenylethanone: (m-nitro-
benzoic acid) (L ꢀ Hmbd) (3)
Similar to 2, the compound 3 of the composition (L ꢀ Hmbd) was
prepared by reacting equal mol of L and m-nitrobenzoic acid, in
which no proton of the m-nitrobenzoic acid was transferred to
the ring N atom of the L. Thus 3 can be classified as an organic
co-crystal. In the asymmetric unit of 3 there existed one molecule
of L, and one molecule of m-nitrobenzoic acid, as shown in Fig. 5.
The bond C5AO1 (1.210(3) Å) in the L is also a typical C@O. The
CAO distances of the COOH group of the m-nitrobenzoic acid are
ranging from 1.208(3) to 1.301(3) Å. The difference (
D is 0.093 Å)
in bond distances between O(2)AC(12) (1.301(3) Å) and
O(3)AC(12) (1.208(3) Å) in the carboxyl group is expected for un-
ionized COOH group. Different from 1, and 2, the O atom of the

134
S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
carbonyl group in the L is at the syn position in respect to the H at
the NACHAN group.
The same as 1, and 2, O atom of the C@O in the cation is at the
trans position in respect to the H at the NACHAN unit. The rms
deviations of the imidazole and the benzene rings in the cation
are 0.0038, and 0.0040 Å, respectively. The two rings are almost
perpendicular to each other with dihedral angle of 83.4°.
One Hmbd and one L form a heteroadduct by the neutral hydro-
gen bond (O(2)AH(2)ꢀ ꢀ ꢀN(2), 2.552(3) Å) between the OH group of
the m-nitrobenzoic acid and the ring N atom of L. Two adjacent
heteroadducts were joined together by the CHAO, and CH2AO
interactions to form a tetra-component adduct. There are two
kinds of CHAO interactions in the tetra-component adduct: one
kind is between the benzene CH of L and the carbonyl group of
the Hmbd with CAO distance of 3.54 Å, the other kind is between
the benzene CH of L and the NO2 group of the m-nitrobenzoic acid
with CAO distance of 3.61 Å. The CH2AO interaction exists be-
tween the CH2 moiety of the L and the C@O of the m-nitrobenzoic
acid with CAO distance of 3.19 Å. In the tetra-component adduct
the two m-nitrobenzoic acids and the two L were antiparallelly ar-
ranged. Under these noncovalent interactions there are close joint
R12ð7Þ and R22ð11Þ ring motifs. The tetra-component adducts were
Because of the presence of the intramolecular hydrogen
bond between the carboxylate group and the phenol group
(O(4)AH(4)ꢀ ꢀ ꢀO(2), 2.504(3) Å), it is generally expected and found
that the carboxylate group is essentially coplanar with the benzene
ring [torsion angle C14AC13AC12AO3, 177.13°]. This feature is
similar to that found in the salicylic acid [42], and in the previously
reported structure of proton-transfer compound based on 5-nsaꢁ
[43]. As expected the OAO separation is essentially in the range
of the documented data [2.489–2.509 Å] [43] because of the planar-
ity of the hydrogen bonded carboxylate unit, but it is slightly
contracted compared with the nonproton transfer examples
(2.547–2.604 Å, mean: 2.588 Å), as a result of deprotonation. The
5-nitro group also varies little conformationally [torsion angle
C16AC17AN3AO6, 175.33°] compared with the reported data
within this set of compounds (175.4–180°) [43].
connected together via the CHAp interaction between 5-CH of
m-nitrobenzoic acid and L with CACg distance of 3.77 Å to form
a ladder running along the b axis direction (Fig. 6). The ladders
were stacked along the c axis direction via the CHAO,
p
A
p
(be-
One anion was bonded to one cation through the hydrogen bond
(N(2)AH(2)ꢀ ꢀ ꢀO(3)#1, 2.652(3) Å) between the NH+ cation and the
carboxylate to form a heteroadduct. So in the solid state, there is
consistently ionic hydrogen bond produced between the NH+ cat-
ion, and the 5-nitrosalicylate ion, which is to be expected [44].
The adjacent heteroadducts were held together by the CHAO
interaction between the nitro group and the benzene CH of the cat-
ion with CAO distance of 3.52 Å to form a 1D chain running along
the b axis direction. Such chains were further joined together via
the interchain CHAO interactions to form a 2D sheet extending
on the ab plane (Fig. 8). Of these interchain CHAO interactions
one kind of CHAO interaction is found between the nitro group
and 4-CH of the imidazole with CAO distance of 3.31 Å, the other
kind of CHAO interaction is formed between 5-CH of the imidazole
and the C@O group of the neighboring cation with CAO distance of
3.17 Å. The sheets were further stacked along the c axis direction
by the CHAO (between the benzene CH of the cation and the
C@O group of the cation belonging to adjacent sheets with CAO
tween the benzene ring of the acid and the benzene ring of L at
the adjacent ladders with CgACg distance of 3.30 Å), and CH2AO
interactions (between CH2 of L and the carbonyl group of the Hmbd
at the neighboring ladder with CAO distance of 3.28 Å) to form a
3D network structure. It should be noted that the adjacent ladders
were not parallel to each other, they made an angle of ca. 30° with
each other. In the 3D structure the third ladder has the same pro-
ject on the ab plane as the first ladder, so does the second ladder
and the fourth ladder. For the presence of such a stacking mode,
in the whole structure of 3 there are no channels.
3.1.4. X-ray structure of 2-(imidazol-1-yl)-1-phenylethanone: (5-nitro-
salicylic acid)[(HL)+ ꢀ (5-nsaꢁ)] (4)
The asymmetric unit of 4 consists of one cation of L, and one an-
ion of 5-nitrosalicylate (Fig. 7). This is a salt where the COOH
groups of 5-nitrosalicylic acids are ionized by proton transfer to
the nitrogen atoms of the 2-(imidazol-1-yl)-1-phenylethanone
moieties, which is also confirmed by the bond distances of
O(3)AC(12) (1.241(3) Å) and O(2)-C(12) (1.269(4) Å) for the
carboxylate.
distance of 3.39 Å), and CHAp interactions (between the benzene
CH of the cation and the imidazole ring with CACg distance of
3.72 Å) to form a 3D network structure. In this case the adjacent
Fig. 8. 2D sheet structure of 4 extending along the ab plane.

S. Jin et al. / Journal of Molecular Structure 1006 (2011) 128–135
135
[4] D.R. Weyna, T. Shattock, P. Vishweshwar, M.J. Zaworotko, Cryst. Growth Des. 9
(2009) 1106.
[5] M. Du, Z.H. Zhang, X.J. Zhao, Cryst. Growth Des. 5 (2005) 1247.
[6] B.R. Bhogala, A. Nangia, Cryst. Growth Des. 3 (2003) 547.
[7] E. Weber, Design of Organic Solids. Topics in Current Chemistry, Springer,
Berlin, 1998. 198.
sheets were slipped some distance from each other that the cations
of adjacent sheets were not parallel to each other, while the anions
belonging to adjacent sheets were antiparallelly arranged.
4. Conclusion
[8] B.R. Bhogala, Cryst. Growth. Des. 3 (2003) 547.
[9] M. Du, Z.H. Zhang, X.J. Zhao, Cryst. Growth. Des. 5 (2005) 1199.
[10] T.R. Shattock, P. Vishweshwar, Z.Q. Wang, M.J. Zaworotko, Cryst. Growth. Des.
5 (2005) 2046.
Four organic acid–base adducts with 3D network structure have
been prepared and structurally characterized. Despite variations in
molecular shape on the acidic components, there all exist strong
intermolecular hydrogen bonds between the acidic components
and the 2-(imidazol-1-yl)-1-phenylethanone.
In the compounds 1, 2, and 4, the imidazolium cations function
as acceptors for ionic hydrogen bonds that organize and orient the
anions, while in compound 3 the imidazole fragments function as
acceptors for neutral hydrogen bonds. This study has demonstrated
that the NAHꢀ ꢀ ꢀO hydrogen bond is the primary intermolecular
force in a family of structures containing the OHꢀ ꢀ ꢀim synthons.
In addition two types of secondary C-HꢀꢀꢀO hydrogen bond (intra-
and interchain CAHꢀ ꢀ ꢀO contacts) were observed, and both have
the same metrics in structure extension. There are also CH2AO,
[11] M. Sarkar, K. Biradha, Cryst. Growth. Des. 6 (2006) 202.
[12] A. Ballabh, D.R. Trivedi, P. Dastidar, Cryst. Growth. Des. 5 (2005) 1545.
[13] D.R. Trivedi, P. Dastidar, Cryst. Growth. Des. 6 (2006) 1022.
[14] C.B. Aakeröy, A.M. Beatty, B.A. Helfrich, Angew. Chem. Int. Ed. 40 (2001) 3240.
[15] J.C. MacDonald, P.C. Dorrestein, M.M. Pilley, Cryst. Growth. Des. 1 (2001) 29.
[16] D.R. Trivedi, A. Ballabh, P. Dastidar, CrystEngComm. 5 (2003) 358.
[17] Y. Akhriff, J. ServerCarrio, J. Garcia-Lozano, J.V. Folgado, A. Sancho, E. Escriva, P.
Vitoria, L. Soto, Cryst. Growth. Des. 6 (2006) 1124.
[18] C.B. Aakeröy, D.J. Salmon, B. Leonard, J.F. Urbina, Cryst. Growth. Des. 5 (2005)
865.
[19] C.B. Aakeröy, D.J. Salmon, M.M. Smith, J. Desper, Cryst. Growth. Des. 6 (2006)
1033.
[20] L.E. Cheruzel, M.S. Mashuta, R.M. Buchanan, Chem. Commun. 2223 (2005).
[21] P.V. Roey, K.A. Bullion, Y. Osawa, R.M. Bowman, D.G. Braun, Acta Crystallogr.
C47 (1991) 1015.
[22] B.Q. Ma, P. Coppens, Cryst. Growth. Des. 4 (2004) 1377.
[23] B.M. Ji, F.F. Jian, P.P. Sun, C.X. Du, K.L. Ding, Z. Kristallogr. NCS 219 (2004) 466.
[24] B.M. Ji, C.X. Du, Y. Zhu, K.L. Ding, J. Chem. Crystallogr. 30 (2000) 783.
[25] B.M. Ji, D.S. Deng, N. Ma, S.B. Miao, X.G. Yang, L.G. Ji, M. Du, Cryst. Growth. Des.
10 (2010) 3060.
[26] B.M. Ji, F.F. Jian, H.L. Xiao, C.X. Du, Anal. Sci.: X-ray Struct. Anal. 20 (2004) x101.
[27] X.M. Song, J.J. Li, X.H. Liu, C.X. Ren, S.M. Shang, Acta Cryst. E67 (2011) o179.
[28] S.W. Jin, W.B. Zhang, D.Q. Wang, H.F. Gao, J.Z. Zhou, R.P. Chen, X.L. Xu, J. Chem.
Crystallogr. 40 (2010) 87.
[29] S.W. Jin, D.Q. Wang, Z.J. Jin, L.Q. Wang, Polish J. Chem. 83 (2009) 1937.
[30] S.W. Jin, D.Q. Wang, J. Chem. Crystallogr. 40 (2010) 914.
[31] I.C. Lennon, J.A. Ramsden, Org. Process Res. Dev. 9 (2005) 110.
[32] R.H. Blessing, Acta Crystallogr. A51 (1995) 33.
CHAp, pAp, and OAp interactions in these compounds.
The results presented herein indicate that the strength and
directionality of the N+AHꢀ ꢀ ꢀOꢁ, OAHꢀ ꢀ ꢀO, and OAHꢀ ꢀ ꢀN hydrogen
bonds (ionic or neutral) between acidic components and 2-(imida-
zol-1-yl)-1-phenylethanone are sufficient to bring about the for-
mation of binary organic salts or cocrystals.
Supporting Information Available
[33] G.M. Sheldrick, SADABS ‘‘Siemens Area Detector Absorption Correction’’,
University of Göttingen, Göttingen, Germany, 1996.
[34] G.M. Sheldrick, Acta Cryst. A64 (2008) 112.
[35] C.B. Aakeröy, J. Desper, M.E. Fasulo, CrystEngComm. 8 (2006) 586.
[36] (a) D.E. Lynch, L.C. Thomas, G. Smith, K.A. Byriel, C.H.L. Kennard, Aust. J. Chem.
51 (1998) 867;
(b) G. Smith, J.M. White, Aust. J. Chem. 54 (2001) 97.
[37] D.H. Williams, I. Fleming, Spectroscopic Methods in Organic Chemistry, fifth
ed., McGraw-hill, London, 1995.
Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic data center, CCDC
Nos. 800022 for 1, 800078 for 2, 800872 for 3, and 799295 for 4.
Copies of this information may be obtained free of charge from
the +44 1223 336 033 or Email: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk.
[38] (a) T. Kagawa, R. Kawai, S. Kashino, M. Haisa, Acta Crystallogr. B32 (1976)
3171;
Acknowledgment
(b) K. Maartmann-Moe, Acta Crystallogr. B25 (1969) 1452;
(c) G.J. Palenik, Acta Crystallogr. B28 (1972) 1633;
(d) A.N. Talukdar, B. Chaudhuri, Acta Crystallogr. B32 (1976) 803;
(e) G. Ferguson, B. Kaitner, D. Lloyd, H. McNab, J. Chem. Res. (S) (1984) 182;
(f) W. Sawka-Dobrowolska, E. Grech, B. Brzezinski, Z. Malarski, L. Sobczyk, J.
Mol. Struct. 356 (1995) 117;
We gratefully acknowledge the financial support of the Educa-
tion Office Foundation of Zhejiang Province (project No.
Y201017321) and the financial support of the Zhejiang A & F Uni-
versity Science Foundation (Project No. 2009FK63).
(g) I. Majerz, Z. Malarski, L. Sobczyk, Chem. Phys. Lett. 274 (1997) 361.
[39] C. Muthamizhchelvan, K. Saminathan, J. Fraanje, R. Peschar, K. Sivakamar, Anal.
Sci. 21 (2005) X61.
[40] J. Bernstein, R.E. Davis, L. Shimoni, N.L. Chang, Angew. Chem. Int. Ed. 34 (1995)
1555.
[41] C. Biswas, M.G.B. Drew, D. Escudero, A. Frontera, A. Ghosh, Eur. J. Inorg. Chem.
(2009) 2238.
[42] M. Sundaralingam, L.H. Jensen, Acta Crystallogr. 18 (1965) 1053.
[43] G. Simith, A.W. Hartono, U.D. Wermuth, P.C. Healy, J.M. White, A.D. Rae, Aust. J.
Chem. 58 (2005) 47.
References
[1] (a) C.J. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885;
(b) G.R. Desiraju, Chem. Commun. (2005) 2995.
[2] (a)J.M. Lehn, J.L. Atwood, J.E.D. Davies, D.D. MacNicol, F. Vögtle (Eds.),
Comprehensive Supramolecular Chemistry, Pergamon, Oxford, UK, 1996;
(b) P.A. Wood, F.H. Allen, E. Pidcock, CrystEngComm. 11 (2009) 1563;
ˇ
(c) D.Z. Veljkovic´, G.V. Janjic´, S.D. Zaric´, CrystEngComm. 13 (2011) 5005;
[44] M. Felloni, A.J. Blake, P. Hubberstey, C. Wilson, M. Schröder, CrystEngComm. 4
(2002) 483.
(d) G.R. Desiraju, Cryst. Growth Des. 11 (2011) 896.
[3] N. Shan, A.D. Bond, W. Jones, Cryst. Eng. 5 (2002) 9.