Structure of seven organic acid-base adducts formed between acids, 2-aminophenol, and 2-amino-4-chlorophenol

Article abstract of DOI:10.1016/j.molstruc.2013.01.012

Studies concentrating on hydrogen bonding between the base of 2-aminophenol, 2-amino-4-chlorophenol, and acidic compounds have led to an increased understanding of the role 2-aminophenol, and 2-amino-4-chlorophenol have in binding with acidic compounds. H

Full text of DOI:10.1016/j.molstruc.2013.01.012

Journal of Molecular Structure 1037 (2013) 242–255
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Structure of seven organic acid–base adducts formed between acids,
2-aminophenol, and 2-amino-4-chlorophenol
b
Shouwen Jin a, , Daqi Wang
⇑
a Tianmu College, ZheJiang A & F University, Lin’An 311300, PR China
b Department of Chemistry, Liaocheng University, Liaocheng 252059, PR China
h i g h l i g h t s
"
"
"
"
Seven organic acid-base adducts have been prepared and structurally characterized.
The hydrogen bond interaction modes in all of the adducts have been ascertained.
The classical hydrogen bonds are the major forces in all of the structures.
The secondary interactions also play important roles in the packing of the adducts.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 19 March 2012
Received in revised form 4 January 2013
Accepted 4 January 2013
Available online 16 January 2013
Studies concentrating on hydrogen bonding between the base of 2-aminophenol, 2-amino-4-chlorophe-
nol, and acidic compounds have led to an increased understanding of the role 2-aminophenol, and 2-
amino-4-chlorophenol have in binding with acidic compounds. Here anhydrous and hydrated multicom-
ponent crystals of 2-aminophenol, and 2-amino-4-chlorophenol have been prepared with 2,4,6-trinitro-
phenol, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, and
fumaric acid. The crystals and complexes of the seven organic acid–base adducts were characterized
by X-ray diffraction analysis, IR, mp, and elemental analysis. The seven crystalline forms reported are
organic salts except 2. All of the adducts were formed in solution and obtained by the slow evaporation
technique. All supramolecular architectures involve extensive NAHꢀ ꢀ ꢀO, OAHꢀ ꢀ ꢀO, and CHꢀ ꢀ ꢀO hydrogen
bonds as well as other nonbonding interactions. The role of weak and strong hydrogen bonding in the
crystal packing is ascertained.
Keywords:
Crystal structure
3D framework
Hydrogen bonds
Acidic compounds
2-Aminophenols derivatives
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
since they form persistent supramolecular heterosynthons with a
number of different complementary functional groups such as
The design and construction of multicomponent supermole-
cules or supramolecular arrays utilizing noncovalent bonding is a
rapidly developing area in supramolecular synthesis. However,
self-assembled supramolecular architectures are often stabilized
as a result of the synergy of a variety of weak noncovalent interac-
tions [1–3]. Thus, the supramolecular synthesis successfully ex-
ploits hydrogen-bonding and other types of non-covalent
interactions, in building supramolecular systems [4].
Carboxylic acids represent one of the most prevalent functional
groups in crystal engineering because they possess a hydrogen
bond donor and acceptor with a geometry that facilitates self-asso-
ciation through supramolecular homosynthons via centrosymmet-
ric dimer or catemer [5–7]. Furthermore, it is now recognized that
carboxylic acids are ideal candidates for multicomponent crystals
amine, and aromatic nitrogen, etc. For instance, much has been
said about the use of carboxyl and pyridinyl groups in the design
of supramolecular systems [8–13]. Besides the COOH group, the
functional groups such as amine, halogen, and phenol OH groups
are all good groups in forming organic solid through non-covalent
interactions [14]. Aminophenols containing equal stoichiometries
of AOH, and ANH2 groups have been widely studied to understand
the supramolecular synthons existing in their assemblies [15].
Among these supramolecular architectures, however, only a very
few reports described the crystals composed of aminophenols
derivatives and carboxylic acids [16].
In order to understand the interaction modes aminophenols
derivatives have in binding with acidic derivatives, we began to
study the aminophenols-acids system, also aiming to find the role
the weak noncovalent interactions played in forming the final
supramolecular frameworks. Thus, in the following, we report
the preparation and crystal structures of seven supramolecular
⇑
Corresponding author. Tel./fax: +86 571 6374 6755.
E-mail address: Jinsw@zafu.edu.cn (S. Jin).
0022-2860/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2013.01.012

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
HO
243
OH
H2N
Cl
NH2
2-amino-4-chlorophenol
2-aminophenol
O2N
NO2
NO2
HO
O
OH
NO2
O
NO2
HO
NO2
2,4,6-trinitrophenol
p-nitrobenzoic acid
3,5-dinitrobenzoic acid
O2N
O
HO
O
OH
HO
HO
OH
NO2
O
O2N
OH
O
fumaric acid
3,5-dinitrosalicylic acid
5-nitrosalicylic acid
Scheme 1. The building blocks discussed in this paper.
compounds assembled via nonbonding interactions between car-
boxylic acids and 2-aminophenol (L1), and 2-amino-4-chlorophe-
nol (L2) (Scheme 1). In this study, we got seven organic
compounds composed of acidic units and 2-aminophenol deriva-
tives, namely (2-aminophenol): (2,4,6-trinitrophenol) [(HL1)+ -
ꢀ (picꢁ), picꢁ = picrate, L1 = 2-aminophenol] (1), (2-amino-4-
chlorophenol): (p-nitrobenzoic acid): H2O [(L2) ꢀ (Hnba) ꢀ H2O,
Hnba = p-nitrobenzoic acid] (2), (2-aminophenol): (3,5-dinitroben-
zoic acid) [(HL1)+ ꢀ (dnbꢁ), dnbꢁ = 3,5-dinitrobenzoate] (3), (2-ami-
no-4-chlorophenol): (3,5-dinitrobenzoic acid) [(HL2)+ ꢀ (dnbꢁ)] (4),
(2-aminophenol): (5-nitrosalicylic acid) [(HL1)+ ꢀ (5-nsaꢁ), 5-
nsaꢁ = 5-nitrosalicylate] (5), (2-amino-4-chlorophenol): (3,5-
dinitrosalicylic acid) [(HL2)+ ꢀ (3,5-dnsꢁ), 3,5-dnsꢁ = 3,5-dinitrosal-
icylate] (6), and (2-amino-4-chlorophenol): (fumaric acid)0.5 : H2O
2.2. Preparation of supramolecular compounds
2.2.1. (2-Aminophenol): (2,4,6-trinitrophenol) [(HL1)+ ꢀ (picꢁ),
picꢁ = picrate] (1)
2-Aminophenol (10.9 mg, 0.10 mmol) was dissolved in 3 mL
methanol. To this solution was added 2,4,6-trinitrophenol
(23 mg, 0.1 mmol) in 10 mL methanol. Brown block crystals were
obtained after several days by slow evaporation of the solvent
(yield: 26 mg, 76.87%). mp 147–148 °C. Elemental analysis: Calc.
for C12H10N4O8 (338.24): C, 42.57; H, 2.96; N, 16.56. Found: C,
42.51; H, 2.89; N, 16.52. Infrared spectrum (KBr disc, cmꢁ1):
3589s(
2940m, 2880m, 2848m, 2820m, 2676w, 2568w, 2370m, 2330m,
1740m, 1645m, 1614s, 1600s, 1560s, 1525s( as(NO2)), 1480m,
1440m, 1360s, 1324s( s(NO2)), 1260s, 1240m, 1210m, 1160m,
m(OH)), 3440s(mas(NH)), 3306s(ms(NH)), 3190s, 3100s,
m
[(HL2)+ ꢀ (fum2ꢁ
)
0.5 ꢀ H2O, fum2ꢁ = fumarate] (7) (Scheme 2).
m
1020m, 980m, 920m, 878m, 840m, 790m, 720m, 680m, 660m,
620m.
2. Experimental section
2.2.2. (2-Amino-4-chlorophenol): (p-nitrobenzoic acid): H2O
[(L2) ꢀ (Hnba) ꢀ H2O, Hnba = p-nitrobenzoic acid] (2)
2.1. Materials and physical measurements
2-Amino-4-chlorophenol (14.3 mg, 0.1 mmol) was dissolved in
2 mL methanol. To this solution was added p-nitrobenzoic acid
(17 mg, 0.1 mmol) in 2 mL methanol. Colorless block crystals were
afforded after several days by slow evaporation of the solvent
(yield: 18 mg, 54.76%, based on L2). mp 213–214 °C. Elemental
analysis: Calc. for C13H13ClN2O6 (328.70): C, 47.46; H, 3.95; N,
8.52. Found: C, 47.37; H, 3.89; N, 8.49. Infrared spectrum (KBr disc,
The chemicals and solvents used in this work are of analytical
grade and available commercially and were used without further
purification. The FT-IR spectra were recorded from KBr pellets in
range 4000–400 cmꢁ1 on a Mattson Alpha-Centauri spectrometer
with 4 cmꢁ1 resolution. Microanalytical (C, H, N) data were ob-
tained with a Perkin–Elmer Model 2400II elemental analyzer.
Melting points of new compounds were recorded on an XT-4 ther-
mal apparatus without correction.
cmꢁ1): 3596s(
2989s, 2926s, 2682w, 2567w, 1763w, 1648s(
m(OH)), 3230s(mas(NH)), 3176s(ms(NH)), 3079 m,
m
(C@O)), 1620m,

244
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
O
N
O
O
OH
O
O N
2
N
O
HO
O
H
H
O
H
O
H
N
H
H
NO
Cl
NH
2
2
2
1
O N
2
O N
2
HO
O
H N
Cl
2
O
O
H
N
O
H
H
O
H
O N
2
O N
2
3
4
HO
O N
2
O
O
H
O
H
H
N
H
O
O N
2
H
H
H
O
O
H
H
N
O
Cl
H
O N
2
O
H
H
5
6
H
H
O
H
O
O
O
H N
Cl
2
O
Cl
NH
2
H
O
O
H
O
H
7
Scheme 2. The seven organic acid–base adducts described in this paper, 1–7.
1572m, 1538s(
m
as(NO2)), 1505m, 1486m, 1448m, 1418m,
(CAO)), 1226m, 1162m, 1094m, 1006m,
3072m, 2989m, 2658w, 2582w, 1979w, 1835w, 1782w, 1664w,
1602s( as(NO2)), 1462w, 1384s( s(-
as(COOꢁ)), 1590m, 1522s(
COOꢁ)), 1323s(
s(NO2)), 1252m, 1194m, 1128m, 1064m, 1011m,
1326s(ms(NO2)), 1288s(
m
m
m
m
952w, 839m, 797w, 724m, 654w, 618w.
m
952m, 903m, 856m, 802m, 753m, 726m, 674m, 626m.
2.2.3. (2-Aminophenol): (3,5-dinitrobenzoic acid) [(HL1)+ ꢀ (dnbꢁ),
dnbꢁ = 3,5-dinitrobenzoate] (3)
2.2.4. (2-Amino-4-chlorophenol): (3,5-dinitrobenzoic acid)
2-Aminophenol (10.9 mg, 0.10 mmol) was dissolved in 3 mL
methanol. To this solution was added 3,5-dinitrobenzoic acid
(21.2 mg, 0.1 mmol) in 4 mL methanol. Brown block crystals were
obtained after several days by slow evaporation of the solvent
(yield: 25 mg, 77.82%). mp 183–185 °C. Elemental analysis: Calc.
for C13H11N3O7 (321.25): C, 48.56; H, 3.42; N, 13.07. Found: C,
48.52; H, 3.37; N, 12.99. Infrared spectrum (KBr disc, cmꢁ1):
[(HL2)+ ꢀ (dnbꢁ), dnbꢁ = 3,5-dinitrobenzoate] (4)
2-Amino-4-chlorophenol (14.3 mg, 0.1 mmol) was dissolved in
2 mL methanol. To this solution was added 3,5-dinitrobenzoic acid
(21.2 mg, 0.1 mmol) in 4 mL methanol. Colorless block crystals
were afforded after several days by slow evaporation of the solvent
(yield: 28 mg, 78.72%, based on L2). mp 178–180 °C. Elemental
analysis: Calc. for C13H10ClN3O7 (355.69): C, 43.86; H, 2.81; N,
11.81. Found: C, 43.82; H, 2.73; N, 11.75. Infrared spectrum (KBr
3579s(m(OH)), 3454s(multiple, mas(NH)), 3346s(ms(NH)), 3158m,

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
245
Table 1
Summary of X-ray crystallographic data for complexes 1–7.
1
2
3
4
Formula
Fw
C
12H10N4O8
C13H13ClN2O6
328.70
C13H11N3O7
321.25
C13H10ClN3O7
355.69
338.24
T, K
298(2)
298(2)
298(2)
298(2)
Wavelength, Å
Crystal system
Space group
a, Å
b, Å
c, Å
0.71073
Triclinic
P-1
0.71073
Triclinic
P-1
0.71073
Monoclinic
P2(1)
9.4853(8)
6.0759(7)
12.0898(13)
90
95.1980(10)
90
693.89(12)
2
1.538
0.128
332
0.42 ꢂ 0.23 ꢂ 0.11
2.62–25.01
ꢁ7 6 h 6 11
ꢁ7 6 k 6 7
ꢁ13 6 l 6 14
3506
0.71073
Triclinic
P-1
8.1626(6)
8.4942(8)
10.3537(11)
79.7650(10)
82.0190(10)
88.947(2)
699.59(11)
2
1.606
0.138
348
0.42 ꢂ 0.18 ꢂ 0.14
2.44–25.01
ꢁ9 6 h 6 9
ꢁ6 6 k 6 10
ꢁ12 6 l 6 12
3531
6.6040(5)
7.4679(6)
15.1801(14)
77.3260(10)
82.0680(10)
88.123(2)
723.42(10)
2
1.509
0.296
340
0.44 ꢂ 0.40 ꢂ 0.18
2.78–25.02
ꢁ7 6 h 6 7
ꢁ8 6 k 6 6
ꢁ18 6 l 6 15
3641
7.3617(5)
7.4375(7)
13.6853(13)
103.183(2)
94.1080(10)
94.8200(10)
723.79(11)
2
a
, °
b, °
c
, °
V, Å3
Z
Dcalcd, Mg/m3
Absorption coefficient, mmꢁ1
F(000)
1.632
0.309
364
Crystal size, mm3
h range, °
0.38 ꢂ 0.33 ꢂ 0.12
2.79–25.02
ꢁ8 6 h 6 3
ꢁ8 6 k 6 8
Limiting indices
ꢁ16 6 l 6 16
3610
Reflections collected
Reflections independent (Rint
)
2434 (0.0191)
1.040
2503 (0.0172)
1.009
2399 (0.0275)
1.006
2494 (0.0149)
1.011
Goodness-of-fit on F2
R indices [I > 2
r
I]
0.0517, 0.1277
0.0759, 0.1501
0.690, ꢁ0.441
0.0407, 0.0976
0.0617, 0.1138
0.300, ꢁ0.252
0.0429, 0.0889
0.0639, 0.1013
0.253, ꢁ0.253
0.0407, 0.0940
0.0631, 0.1094
0.218, ꢁ0.238
R indices (all data)
Largest diff. peak and hole, e Åꢁ3
5
6
7
Formula
Fw
C
13H12N2O6
C13H12ClN3O9
389.71
C8H10ClNO4
219.62
292.25
T, K
298(2)
298(2)
298(2)
Wavelength, Å
Crystal system
Space group
a, Å
b, Å
c, Å
0.71073
Triclinic
P-1
0.71073
Monoclinic
P2(1)/n
7.1541(6)
7.2988(7)
29.388(2)
90
96.3860(10)
90
1525.0(2)
4
1.697
0.311
800
0.48 ꢂ 0.37 ꢂ 0.08
2.79–25.02
ꢁ8 6 h 6 8
ꢁ8 6 k 6 8
ꢁ21 6 l 6 34
7123
0.71073
Monoclinic
P2(1)/c
5.645(3)
21.777(12)
7.992(4)
90
90.579(6)
90
982.4(9)
4
1.485
0.377
456
0.22 ꢂ 0.19 ꢂ 0.15
2.71–25.01
ꢁ6 6 h 6 6
ꢁ25 6 k 6 12
ꢁ9 6 l 6 9
5103
10.7020(10)
10.7709(11)
12.4031(13)
108.702(2)
97.5900(10)
92.7600(10)
1336.1(2)
4
1.453
0.117
608
0.27 ꢂ 0.25 ꢂ 0.10
2.40–25.02
ꢁ9 6 h 6 12
ꢁ12 6 k 6 12
ꢁ12 6 l 6 14
6633
a
, °
b, °
c
, °
V, Å3
Z
Dcalcd, Mg/m3
Absorption coefficient, mmꢁ1
F(000)
Crystal size, mm3
h range, °
Limiting indices
Reflections collected
Reflections independent (Rint
)
4601 (0.0826)
1.021
2685 (0.0615)
0.949
1744 (0.0622)
1.042
Goodness-of-fit on F2
R indices [I > 2
r
I]
0.1444, 0.3276
0.2878, 0.4527
0.481, ꢁ0.434
0.0443, 0.1011
0.0751, 0.1133
0.222, ꢁ0.233
0.0459, 0.1289
0.0574, 0.1366
0.405, ꢁ0.370
R indices (all data)
Largest diff. peak and hole, e Åꢁ3
disc, cmꢁ1): 3612s(
3087m, 2984s, 2688w, 2559w, 1626m, 1598s(
m
(OH)), 3488s(
m
as(NH)), 3296s(
m
s(NH)), 3174m,
as(COOꢁ)),
s(COOꢁ)),
as(NO2)), 1282m, 1246m, 1202m, 1162m, 1094m, 1006m,
C
13H12N2O6 (292.25): C, 53.38; H, 4.10; N, 9.58. Found: C, 53.33;
H, 4.02; N, 9.54. Infrared spectrum (KBr disc, cmꢁ1):
3585s( (OH)), 3472s(multiple, as(NH)), 3362s( s(NH)), 3118m,
3046m, 2967m, 2884m, 2689w, 2573w, 1634m, 1586s(
as(COOꢁ)),
1552m, 1526s( as(NO2)), 1486w, 1394s(
s(COOꢁ)), 1366m,
1321s( s(NO2)), 1270m, 1225m, 1193m, 1131m, 1079m, 1013m,
m
m
1536s(mas(NO2)), 1492m, 1464m, 1414m, 1382s(
m
m
m
1320s(
m
m
952w, 861w, 811m, 757w, 714m, 665w, 613w.
m
m
m
2.2.5. (2-Aminophenol): (5-nitrosalicylic acid) [(HL1)+ ꢀ (5-nsaꢁ), 5-
nsaꢁ = 5-nitrosalicylate] (5)
952m, 852m, 806m, 760m, 716m, 680m, 637m.
2-Aminophenol (10.9 mg, 0.10 mmol) dissolved in 2 mL etha-
nol. To this solution was added 5-nitrosalicylic acid (18.3 mg,
0.1 mmol) in 4 mL ethanol. Yellow prisms were afforded after sev-
eral days of slow evaporation of the solvent, yield: 29 mg, 78.52%
(based on L1). mp 196–198 °C. Elemental analysis: Calc. for
2.2.6. (2-Amino-4-chlorophenol): (3,5-dinitrosalicylic acid)
[(HL2)+ ꢀ (3,5-dnsꢁ), 3,5-dnsꢁ = 3,5-dinitrosalicylate] (6)
2-Amino-4-chlorophenol (14.3 mg, 0.1 mmol) was dissolved in
2 mL methanol. To this solution was added was added 3,5-dinitro-
salicylic acid (22.8 mg, 0.1 mmol) in 6 mL ethanol. Colorless block

246
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
Table 2
crystals were afforded after several days by slow evaporation of the
solvent (yield: 28 mg, 71.85%, based on L2). mp 158–160 °C. Ele-
mental analysis: Calc. for C13H12ClN3O9 (389.71): C, 40.03; H,
3.08; N, 10.77. Found: C, 39.95; H, 3.04; N, 10.69. Infrared spectrum
Selected bond lengths (Å) and angles (°) for 1–7.
1
N(1)AC(2)
N(3)AC(10)
O(1)AC(1)
C(2)AN(1)AH(1A)
H(1A)AN(1)AH(1B)
H(1A)AN(1)AH(1C)
C(3)AC(2)AN(1)
1.465(3)
1.447(4)
1.364(3)
109.5
109.5
109.5
N(2)AC(8)
N(4)AC(12)
O(2)AC(7)
C(2)AN(1)AH(1B)
C(2)AN(1)AH(1C)
H(1B)AN(1)AH(1C)
C(1)AC(2)AN(1)
1.461(3)
1.460(3)
1.262(3)
109.5
109.5
109.5
(KBr disc, cmꢁ1): 3602s
(
m
(OH)), 3486s(multiple,
s(NH)), 3066m, 2968m, 2684w, 2579w, 1637m, 1605m,
as(COOꢁ)), 1540s( s(COOꢁ)),
as(NO2)), 1486w, 1388s(
s(NO2)), 1279m, 1202m, 1159m, 1022m, 952m,
mas(NH)),
3308s(
1596s(
1354m, 1312s(
m
m
m
m
m
120.3(2)
118.2(2)
846m, 759m, 648m, 604m.
2
Cl(1)AC(11)
N(1)AO(4)
N(2)AC(9)
O(2)AC(1)
O(3)AN(1)AO(4)
1.743(2)
1.217(3)
1.396(3)
1.247(3)
122.6(2)
N(1)AO(3)
N(1)AC(5)
O(1)AC(1)
O(5)AC(8)
O(2)AC(1)AO(1)
1.216(3)
1.471(3)
1.281(3)
1.369(3)
123.4(2)
2.2.7. (2-Amino-4-chlorophenol): (fumaric acid)0.5: H2O
[(HL2+) ꢀ (fum2ꢁ
)
0.5 ꢀ H2O, fum2ꢁ = fumarate] (7)
2-Amino-4-chlorophenol (14.3 mg, 0.1 mmol) was dissolved in
2 mL methanol. To this solution was added fumaric acid (12 mg,
0.1 mmol) in 8 mL ethanol. Colorless block crystals were afforded
after several days by slow evaporation of the solvent (yield:
18 mg, 81.96%, based on L2). mp 239–240 °C. Elemental analysis:
Calc. for C8H10ClNO4 (219.62): C, 43.71; H, 4.55; N, 6.37. Found:
C, 43.67; H, 4.52; N, 6.31. Infrared spectrum (KBr disc, cmꢁ1):
3
N(1)AC(2)
N(3)AC(12)
O(2)AC(7)
O(2)AC(7)AO(3)
1.464(4)
1.470(4)
1.240(4)
125.7(3)
N(2)AC(10)
O(1)AC(1)
O(3)AC(7)
1.469(4)
1.377(4)
1.255(3)
4
Cl(1)AC(4)
N(2)AC(10)
O(1)AC(1)
O(7)AC(7)
1.740(2)
1.473(3)
1.350(3)
1.241(3)
N(1)AC(2)
N(3)AC(12)
O(2)AC(7)
1.462(3)
1.476(3)
1.270(3)
126.2(2)
3588s(
2689w, 2587w, 1642s, 1612s, 1591s(
1455m, 1380s(
s(COOꢁ)), 1343s, 1306m, 1284m, 1219m, 1167m,
m
(OH)), 3427s(
m
as(NH)), 3328s(
ms(NH)), 3131s, 2958m,
m
as(COOꢁ)), 1562m, 1505m,
m
O(7)AC(7)AO(2)
1009m, 938m, 842 m, 759 m, 648 m.
5
N(1)AO(4)
N(1)AC(5)
N(2)AO(9)
N(3)AC(16)
O(1)AC(2)
O(3)AC(1)
O(7)AC(8)
O(11)AC(15)
O(4)AN(1)AO(5)
O(2)AC(1)AO(3)
1.221(13)
1.457(13)
1.247(11)
1.456(12)
1.340(12)
1.270(12)
1.290(14)
1.364(12)
122.3(10)
124.1(9)
N(1)AO(5)
1.241(11)
1.230(10)
1.440(13)
1.439(13)
1.253(12)
1.343(12)
1.217(14)
1.344(13)
120.6(10)
125.7(10)
N(2)AO(10)
N(2)AC(12)
N(4)AC(22)
O(2)AC(1)
O(6)AC(9)
O(8)AC(8)
O(12)AC(21)
O(10)AN(2)AO(9)
O(8)AC(8)AO(7)
2.3. X-ray crystallography
Suitable crystals were performed on a Bruker SMART 1000 CCD
diffractometer using Mo Ka radiation (k = 0.71073 Å). Data collec-
tions and reductions were performed using the SMART and SAINT
software [17,18]. The structures were solved by direct methods,
and the non-hydrogen atoms were subjected to anisotropic refine-
ment by full-matrix least squares on F2 using SHELXTL package
[19]. Hydrogen atom positions for the seven structures were gen-
erated geometrically. Further details of the structural analysis are
summarized in Table 1. Selected bond lengths and angles for com-
pounds 1–7 are listed in Table 2; the relevant hydrogen bond
parameters are provided in Table 3. The IR bands which indicate
chemical functionalities in the resulting compounds are given in
Table 4.
6
Cl(1)AC(4)
N(2)AC(10)
O(1)AC(1)
O(3)AC(7)
O(2)AC(7)AO(3)
1.722(3)
1.444(3)
1.358(3)
1.303(3)
121.5(2)
N(1)AC(2)
N(3)AC(12)
O(2)AC(7)
O(4)AC(9)
1.468(3)
1.462(3)
1.212(3)
1.301(3)
7
Cl(1)AC(4)
O(1)AC(1)
O(3)AC(7)
1.746(3)
1.363(3)
1.264(3)
N(1)AC(2)
O(2)AC(7)
O(2)AC(7)AO(3)
1.469(3)
1.255(3)
124.36(19)
3. Results and discussion
for COOH groups. The bands at ca. 1530 and 1320 cmꢁ1 were
attributed to the as(NO2) and s(NO2), respectively [20].
3.1. Syntheses and general characterization
m
m
2-Aminophenol, and 2-amino-4-chlorophenol both have good
solubility in common organic solvents, such as CH3OH, C2H5OH,
CH3CN, CHCl3, and CH2Cl2. For the preparation of 1–7, the acidic
components were mixed directly with the base in methanol and/
or ethanol solvents in 1:1 ratio, which was allowed to evaporate
at ambient conditions to give the final crystalline products. The
molecular structures and their atom labeling schemes for the seven
structures are shown in Figs. 1, 3, 5, 7, 9, 11 and 13, respectively.
The elemental analyses for the seven compounds are in good
agreement with their compositions. The infrared spectra of 1–7
are consistent with their chemical formulas determined by ele-
mental analysis and further confirmed by X-ray diffraction
analysis.
3.2. Structural descriptions
3.2.1. X-ray structure of (2-aminophenol): (2,4,6-trinitrophenol)
[(HL1)+ ꢀ (picꢁ), picꢁ = picrate, L1 = 2-aminophenol], (1)
Salt 1 was prepared by reacting of a methanol solution of 2-ami-
nophenol and 2,4,6-trinitrophenol in 1:1 ratio, which crystallizes
as triclinic pale yellow crystals in the space group P-1. The asym-
metric unit of 1 consists of a monocation of 2-aminophenol, and
one anion of picrate, as shown in Fig. 1.
This is a salt where the OH groups of 2,4,6-trinitrophenol are
ionized by proton transfer to the nitrogen atom (N(1)) of the 2-
aminophenol moieties, which is also confirmed by the bond dis-
tance of O(2)AC(7) (1.262(3) Å) for phenolate (1.24 0.01 Å) [21].
In the compound, there is one ion pair without solvent molecules,
which is well agreement with the micro-analysis results. The
N(1)AC(2) bond length is 1.465(3) Å, and is approximately equal
to a CAN single-bond length, indicating that atom N(1) of the ami-
no group must be sp3 hybridized. This is also supported by the an-
gles around C(2) (C(3)AC(2)AN(1), 120.3(2)°; C(1)AC(2)AN(1),
The very strong and broad features at 3612–3176 cmꢁ1 arise
from OAH or NAH stretching frequencies. The wave numbers of
protonated NH2 group (in 1, 3, 4, 5, 6, 7) were larger than the wave
numbers of the NH2 group in the compound 2. Aromatic ring
stretching and bending are in the regions of 1500–1630 cmꢁ1
and 600–750 cmꢁ1, respectively. The salts 3–7 show the character-
istic bands for COOꢁ groups. Compound 2 displays strong IR peaks

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
247
Table 3
Hydrogen bond distances and angles in studied structures 1–7.
DAHꢀ ꢀ ꢀA
d(DAH) (Å)
d(Hꢀ ꢀ ꢀA) (Å)
d(Dꢀ ꢀ ꢀA) (Å)
<(DHA) (°)
1
O(1)AH(1)ꢀ ꢀ ꢀO(5)#1
N(1)AH(1C)ꢀ ꢀ ꢀO(7)
N(1)AH(1B)ꢀ ꢀ ꢀO(2)#2
N(1)AH(1A)ꢀ ꢀ ꢀO(3)#3
N(1)AH(1A)ꢀ ꢀ ꢀO(2)#3
0.82
0.89
0.89
0.89
0.89
2.03
2.07
1.95
2.46
1.93
2.837(3)
2.924(3)
2.823(3)
2.964(3)
2.799(3)
167.2
161.2
167.6
116.5
166.5
2
O(6)AH(6D)ꢀ ꢀ ꢀN(2)#1
O(6)AH(6C)ꢀ ꢀ ꢀO(4)#2
O(5)AH(5)ꢀ ꢀ ꢀO(6)#3
O(1)AH(1)ꢀ ꢀ ꢀO(2)#4
N(2)AH(2A)ꢀ ꢀ ꢀO(5)#5
N(2)AH(2A)ꢀ ꢀ ꢀO(3)#6
0.85
0.85
0.82
0.82
0.86
0.86
2.02
2.20
1.87
1.80
2.28
2.32
2.865(3)
3.045(3)
2.671(2)
2.618(2)
3.034(3)
3.101(3)
177.5
177.6
166.6
171.6
146.0
150.5
3
N(1)AH(1C)ꢀ ꢀ ꢀO(2)#1
N(1)AH(1B)ꢀ ꢀ ꢀO(1)#2
N(1)AH(1A)ꢀ ꢀ ꢀO(3)#3
0.89
0.89
0.89
1.89
2.04
1.89
2.768(3)
2.873(3)
2.769(3)
170.1
155.1
171.9
4
O(1)AH(1)ꢀ ꢀ ꢀO(7)#1
N(1)AH(1C)ꢀ ꢀ ꢀO(2)#2
N(1)AH(1B)ꢀ ꢀ ꢀO(1)#3
N(1)AH(1B)ꢀ ꢀ ꢀO(3)#3
N(1)AH(1B)ꢀ ꢀ ꢀO(1)
N(1)AH(1A)ꢀ ꢀ ꢀO(2)#4
0.82
0.89
0.89
0.89
0.89
0.89
1.78
1.93
2.50
2.30
2.19
1.89
2.526(2)
2.793(3)
2.987(2)
3.093(2)
2.670(2)
2.734(2)
149.8
162.7
114.7
148.0
113.3
158.4
5
O(12)AH(12)ꢀ ꢀ ꢀO(7)#1
O(11)AH(11A)ꢀ ꢀ ꢀO(2)#2
O(6)AH(6)ꢀ ꢀ ꢀO(7)
0.82
0.82
0.82
0.82
0.89
0.89
0.89
0.89
0.89
0.89
0.89
0.89
1.88
1.81
1.78
1.81
2.21
2.30
1.90
2.43
2.38
2.25
2.19
1.78
2.672(10)
2.624(9)
162.7
169.3
148.9
148.1
148.3
166.5
166.3
131.3
144.1
110.5
155.2
158.7
2.518(11)
2.539(11)
3.005(11)
3.170(11)
2.768(11)
3.092(11)
3.146(12)
2.694(10)
3.026(11)
2.632(11)
O(1)AH(1)ꢀ ꢀ ꢀO(2)
N(4)AH(4C)ꢀ ꢀ ꢀO(10)#3
N(4)AH(4B)ꢀ ꢀ ꢀO(3)
N(4)AH(4A)ꢀ ꢀ ꢀO(3)#2
N(3)AH(3C)ꢀ ꢀ ꢀO(4)#4
N(3)AH(3C)ꢀ ꢀ ꢀO(5)#4
N(3)AH(3B)ꢀ ꢀ ꢀO(11)
N(3)AH(3B)ꢀ ꢀ ꢀO(3)
N(3)AH(3A)ꢀ ꢀ ꢀO(8)#1
6
O(9)AH(9D)ꢀ ꢀ ꢀO(4)#1
O(9)AH(9C)ꢀ ꢀ ꢀO(5)
O(3)AH(3)ꢀ ꢀ ꢀO(4)
O(1)AH(1)ꢀ ꢀ ꢀO(2)#2
N(1)AH(1C)ꢀ ꢀ ꢀO(5)
N(1)AH(1C)ꢀ ꢀ ꢀO(4)
N(1)AH(1C)ꢀ ꢀ ꢀO(3)#1
N(1)AH(1B)ꢀ ꢀ ꢀO(9)#3
N(1)AH(1A)ꢀ ꢀ ꢀO(9)#4
0.85
0.85
0.82
0.82
0.89
0.89
0.89
0.89
0.89
1.94
2.11
1.65
1.81
2.56
2.49
2.32
1.98
1.93
2.724(2)
2.894(3)
2.424(3)
2.609(3)
3.289(3)
3.069(3)
2.989(3)
2.870(3)
2.818(3)
152.1
152.8
155.2
166.3
140.3
123.1
132.1
178.5
173.1
7
O(4)AH(4D)ꢀ ꢀ ꢀO(3)#2
O(4)AH(4C)ꢀ ꢀ ꢀCl(1)#3
O(4)AH(4C)ꢀ ꢀ ꢀO(2)#4
O(1)AH(1)ꢀ ꢀ ꢀO(2)#4
N(1)AH(1C)ꢀ ꢀ ꢀO(3)#5
N(1)AH(1B)ꢀ ꢀ ꢀO(3)#6
N(1)AH(1A)ꢀ ꢀ ꢀO(4)#7
0.85
0.85
0.85
0.82
0.89
0.89
0.89
2.00
2.96
2.07
1.85
1.94
1.95
1.93
2.838(3)
3.414(2)
2.908(3)
2.668(2)
2.828(3)
2.812(3)
2.817(3)
170.2
115.5
170.2
177.5
175.8
163.9
178.6
Symmetry transformations used to generate equivalent atoms for 1: #1 x + 1, y, z ꢁ 1; #2 ꢁx + 1, ꢁy + 1, ꢁz + 1; #3 x, y ꢁ 1, z. Symmetry transformations used to generate
equivalent atoms for 2: #1 x, y ꢁ 1, z; #2 ꢁx + 1, ꢁy + 1, ꢁz; #3 x + 1, y + 1, z; #4 ꢁx, ꢁy, ꢁz + 1; #5 ꢁx + 1, ꢁy + 2, ꢁz; #6 x ꢁ 1, y, z. Symmetry transformations used to
generate equivalent atoms for 3: #1 ꢁx + 1, y ꢁ 1/2, ꢁz; #2 ꢁx, y + 1/2, ꢁz; #3 ꢁx + 1, y + 1/2, ꢁz. Symmetry transformations used to generate equivalent atoms for 4: #1 x ꢁ 1,
y ꢁ 1, z; #2 x, y ꢁ 1, z; #3 ꢁx + 1, ꢁy, ꢁz; #4 ꢁx + 2, ꢁy + 1, ꢁz. Symmetry transformations used to generate equivalent atoms for 5: #1 ꢁx + 1, ꢁy + 1, ꢁz; #2 ꢁx, ꢁy + 1,
ꢁz + 1; #3 ꢁx + 1, ꢁy + 2, ꢁz + 1; #4 ꢁx, ꢁy, ꢁz. Symmetry transformations used to generate equivalent atoms for 6: #1 ꢁx + 1/2, y ꢁ 1/2, ꢁz + 1/2; #2 x + 1, y ꢁ 1, z; #3
ꢁx + 3/2, y + 1/2, ꢁz + 1/2; #4 x, y + 1, z. Symmetry transformations used to generate equivalent atoms for 7: #2 ꢁx + 1, ꢁy + 1, ꢁz + 1; #3 x + 1, ꢁy + 1/2, z + 1/2; #4 x + 1,
y ꢁ 1, z; #5 ꢁx + 1, ꢁy + 1, ꢁz; #6 x, yꢁ1, z; #7 xꢁ1, y, z ꢁ 1.
118.2(2)°), and the bond angles concerning N(1) (C(2)AN(1)AH(1A),
C(2)AN(1)AH(1C), C(2)AN(1)AH(1B), H(1A)AN(1)AH(1B), H(1A)A
N(1)AH(1C), and H(1B)AN(1)AH(1C) are all 109.5°, indicating very
nearly perfect sp3 hybridization). The N(1)AC(2) bond (1.465(3) Å)
is longer by 0.05 Å than that (1.416(2) Å) in neutral 2-aminophenol
[22], yet it is similar to the corresponding value at the salt of 2-ami-
nophenol-HClO4 [23]. The CAOH and CAC bonds within the aromatic
ring of the cation are comparable to that found in the crystal of a neu-
tral 2-aminophenol [22].
The rms deviation of the phenyl ring of the picrate is 0.0211 Å,
the ortho-nitro groups (N2AO3AO4, and N4AO7AO8) deviate
from the phenyl ring plane and have dihedral angles of 34.7°,
and 19.3° respectively with the phenyl plane, whereas the para-ni-
tro group lies almost in the phenyl plane [with a dihedral angle of

248
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
Table 4
Character IR bands of chemical functionalities of the four organic salts 1–7.
Compound
m
(OH)
m
as(NH)
m
s(NH)
m
(C@O)
m
as(COO)
m
s(COO)
m
(CAO)
m
as(NO2)
ms(NO2)
1
2
3
4
5
6
7
3589s
3596s
3579s
3612s
3585s
3602s
3588s
3440s
3230s
3454s
3488s
3472s
3486s
3427s
3306s
3176s
3346s
3296s
3362s
3308s
3328s
1525s
1538s
1522s
1536s
1526s
1540s
1324s
1326s
1323s
1320s
1321s
1312s
1648s
1288s
1602s
1598s
1586s
1596s
1591s
1384s
1382s
1394s
1388s
1380s
Fig. 1. The structure of 1, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
Fig. 2. 2D sheet structure of 1 extending along the direction that made an angle of ca 45° with the bc plane.
4.9° between the N3AO5AO6 group and the phenyl ring]. The two
ortho-nitro groups intersect at an angle of 25.7° with each other,
while the para-nitro group made dihedral angles of 30.0° (with
N2AO3AO4), and 17.7° (with N4AO7AO8) with the two ortho ni-
tro groups respectively. These structural data are similar to those
in other structurally described picrates [24].
One anion is bonded to one cation through the bifurcated
NAHꢀ ꢀ ꢀO hydrogen bonds produced between the aminium cation
and the phenolate and one ortho-nitro group with NAO distances
of 2.799(3)–2.964(3) Å. In this case the NH unit and the two O
atoms involved in the hydrogen bonds generated a R21ð6Þ motif
according to [25]. Herein the phenyl ring of the cation and the phe-
nyl ring of the anion are almost perpendicular to each other with a
dihedral angle of 80.2° between the two rings. Under the NAHꢀ ꢀ ꢀO
hydrogen bonds the cation and the anion formed a bicomponent
adduct. Such kind of bicomponent adducts were joined together
via OAHꢀ ꢀ ꢀO hydrogen bond between the phenol unit of the cation
and the para-nitro group of the neighboring bicomponent hete-
roadduct with NAO distance of 2.837(3) Å to form a 1D chain run-
ning along the c axis direction. The adjacent chains were combined
together through NAHꢀ ꢀ ꢀO hydrogen bond between the aminium
cation and the ortho nitro group with NAO distance of
2.924(3) Å, and OAO contact between the ortho nitro groups of
the adjacent chains with OAO separation of 2.864 Å to form 2D
sheet extending along the direction that made an angle of ca. 45°
with the bc plane (Fig. 2). Two neighboring sheets were held to-
gether by the CHAO association between the aromatic 3-CH of
the cation of one sheet and the ortho nitro group of its neighboring

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
249
proton transfer to the N atoms of the 2-amino-4-chlorophenol
moieties, which is also confirmed by the bond length of C9AN2
which has similar bond length with the corresponding value in
the crystals of 2-amino-4-chlorophenol [26].
Here the difference between the pairs of CAO bond distances of
O(1)AC(1) (1.281(3) Å), and O(2)AC(1) (1.247(3) Å) is relatively
small, which may be explained by the fact the formation of single
or multiple hydrogen bonds at one oxygen atom should cause the
associated CAO bond to lengthen. Here the O(2) involves in the
hydrogen bond, while the O1 does not.
The carboxyl and the nitro groups deviated by 4.3°, and 1.6°
respectively from the benzene ring composed of C2AC7. The
r.m.s deviations of the phenyl rings of the p-nitrobenzoic acid
and L2 from the mean planes of the rings are 0.0033 Å, and
0.0058 Å, respectively, both rings made dihedral angle of 0.8° with
each other. Different from 1, here the aromatic rings of the acid,
and the base components are almost in the same plane.
Fig. 3. The structure of 2, showing the atom-numbering scheme. Displacement
ellipsoids were drawn at the 30% probability level.
Two L2 form homodimers via a pair of NAHꢀ ꢀ ꢀO hydrogen
bonds between the amino group and the phenolic group with
NAO distance of 3.034(3) Å. Two Hnba molecules are also aggre-
gated together by a pair of CHAO associations between the 3-CH
of the phenyl unit and the p-nitro group with CAO distance of
3.550 Å to form a homodimer. Such two kinds of homodimers were
linked together by the CHAO contact between the 5-CH of the 2-
amino-4-chlorophenol and the carbonyl group of the p-nitroben-
zoic acid with CAO distance of 3.463 Å to form a 1D chain running
along the c axis direction. The chains were combined together by
the interchain NAHꢀ ꢀ ꢀO hydrogen bond between the amino group
of the L2 and the p-nitro group of Hnba with NAO distance of
3.101(3) Å to form 2D sheet extending on the ac plane (Fig. 4). In
the sheet the water molecules were stitched between the adjacent
chains via the OAHꢀ ꢀ ꢀO hydrogen bonds (O(5)AH(5)ꢀ ꢀ ꢀO(6)#3, and
O(6)AH(6C)ꢀ ꢀ ꢀO(4)#2), and CHAO association between the 2-CH of
the p-nitrobenzoic acid and the water molecule with CAO distance
of 3.460 Å. It is worthy to point out that the adjacent chains in the
sheet were slipped the distance of ca. c axis length along the c axis
direction. While the first chain has the same projection as the third
chain when we viewed from the a axis direction, so does the sec-
ond chain and the fourth chain. The sheets were further stacked
along the b axis direction by the OAHꢀ ꢀ ꢀN hydrogen bond between
the water molecule and the amino group of L2 with NAO distance
of 2.865(3) Å to form 3D layer network structure. Herein the adja-
cent sheets were slipped some distance from each other along the
a, and c axes directions, respectively.
Fig. 4. 2D sheet structure of 2 extending along the ac plane.
sheet with CAO distance of 3.365 Å to form double sheet structure.
It is worthy to note that the corresponding cations and anions in
the same sheet were parallelly arranged, respectively; while the
corresponding cations and anions at different sheets in the double
sheet were antiparallelly arranged, respectively. The double sheets
were further stacked along the direction that is perpendicular with
its extending direction via the intersheet NAHꢀ ꢀ ꢀO hydrogen bond
between the aminium group and the phenolate with NAO distance
of 2.823(3) Å to form 3D layer network structure. In this regard the
neighboring double sheets were slipped some distance from each
other along the b, and c axes directions, respectively.
3.2.3. X-ray structure of (2-aminophenol): (3,5-dinitrobenzoic acid)
[(HL1)+ ꢀ (dnbꢁ), dnbꢁ = 3,5-dinitrobenzoate], (3)
Compound 3 was prepared by reacting of a methanol solution of
2-aminophenol and 3,5-dinitrobenzoic acid in 1:1 ratio, which
crystallizes as monoclinic pale yellow crystals in the centrosym-
metric space group P2(1). The asymmetric unit of 3 consists of a
cation of L1, and one anion of 3,5-dinitrobenzoate, as shown in
Fig. 5.
Compound 3 is a salt where the COOH groups of 3,5-dinitroben-
zoic acids are ionized by proton transfer to the nitrogen atoms of
the L1, which is also confirmed by the bond distances of
O(2)AC(7) (1.240(4) Å) and O(3)AC(7) (1.255(3) Å) for the carbox-
3.2.2. X-ray structure of (2-amino-4-chlorophenol): (p-nitrobenzoic
acid): H2O [(L2) ꢀ (Hnba) ꢀ H2O, Hnba = p-nitrobenzoic acid] (2)
The compound 2 of the composition [(L2) ꢀ (Hnba) ꢀ H2O] was
prepared by reaction equal mol of 2-amino-4-chlorophenol and
p-nitrobenzoic acid, which crystallizes as triclinic colorless block
crystals in the space group P-1. The asymmetric unit of two con-
sists of one L2 molecule, one p-nitrobenzoic acid molecule, and
one water molecule, as shown in Fig. 3. This is a cocrystal where
the COOH groups of the p-nitrobenzoic acids are not ionized by
ylates. The difference (
D is 0.015 Å) in bond distances between
O(2)AC(7) (1.240(4) Å) and O(3)AC(7) (1.255(3) Å) in the carboxyl-
ate group in compound 3 is in the range for ionized COOH groups
[27].
In the compound, there is one ion pair without solvent molecules,
which is well agreement with the micro-analysis results. In com-
pound 3, there exist strong electrostatic interactions between the
charged cation units of NH+ and the anion of 3,5-dinitrobenzoate.

250
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
Fig. 5. The structure of 3, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
Fig. 6. 2D corrugated sheet structure of 3 that is running parallel to the bc plane.
One cation and one anion generate a bicomponent adduct via
the ionic N+-Hꢀ ꢀ ꢀOꢁ hydrogen bond between the aminium cation
and the carboxylate with NAO distance of 2.768(3) Å. Such kind
of bicomponent adducts were linked together by the CHAO inter-
action between the phenyl CH (3-CH) of the cation and the nitro
group with CAO distance of 3.432 Å to form a 1D wave chain run-
ning along the c axis direction. Here the distance (ca. 3.627(3) Å)
between the O1 and O2 is too great to imply OAHꢀ ꢀ ꢀO hydrogen
bond. The 1D wave chains were connected together by the CHAO
interaction between the phenyl CH (3-CH) of the cation and the
carboxylate with CAO distance of 3.271 Å, NAHꢀ ꢀ ꢀO association be-
tween the aminium group and the same O atom of the same car-
boxylate group that is involved in CHAO interaction with NAO
distance of 2.769(3) Å, and O–
p interaction between the nitro
group and the phenyl ring of the anion with OACg distance of
3.060 Å at the neighboring chains to form a 2D corrugated sheet
structure (Fig. 6). In this regard the O–p interaction is much stron-
ger than the archived result (3.59 Å) [28]. The corresponding an-
ions and cations in the sheet were parallel to each other
respectively. Two neighboring 2D corrugated sheets were joined
Fig. 7. The structure of 4, showing the atom-numbering scheme. Displacement
ellipsoids were drawn at the 30% probability level.
together via the same side of the sheet by the O–p interaction be-
tween the nitro group and the phenyl ring of the anion with OACg
distance of 3.080 Å to form 2D double sheet structure. The 2D dou-
ble sheets were further stacked along the a axis direction through
the intersheet NAHꢀ ꢀ ꢀO hydrogen bond between the aminium unit
and the phenol group of the cation at adjacent double sheets with
OAN distance of 2.873(3) Å, OAN association (with OAN distance
of 2.885 Å), and OAO (with OAO distance of 2.965 Å) contact to
form 3D network structure.
3.2.4. X-ray structure of (2-amino-4-chlorophenol): (3,5-
dinitrobenzoic acid) [(HL2)+ ꢀ (dnbꢁ), dnbꢁ = 3,5-dinitrobenzoate] (4)
Similar to compound 3, in 4 the asymmetric unit is occupied by
one anion of 3,5-dinitrobenzoic acid, and a cation of (HL2)+ (Fig. 7).
The proton of the COOH group has transferred to the N atom of the
L2 moiety. The assignment of 4 as a salt is based on successful

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
251
Fig. 8. 2D sheet structure of 4 extending parallel to the ac plane.
refinement of the relevant H atoms using X-ray data also. One cat-
ion is bonded to one anion through the OAHꢀ ꢀ ꢀO hydrogen bond
between the phenol group (donor) and the carboxylate with
OAO separation of 2.526(2) Å to form a heteroadduct. The parallel
heteroadducts were linked together along the a axis direction by
the CHAO interaction between the 3-CH of the cation and the nitro
group of the anion with CAO distance of 3.388 Å to form a 1D chain
running along the a axis direction. Two neighboring chains were
combined together by the NAHꢀ ꢀ ꢀO hydrogen bond between the
aminium group and the nitro group with NAO distance of
3.093(2) Å to form 1D double chain. The cations in the two chains
at the double chain were antiparallely arranged, so did the anions.
The double chains were further joined together by the CHAO asso-
ciation (there are a pair of CHAO interactions with CAO distance of
3.592 Å between the anions to form a R22ð10Þ ring, there is also a
CHAO contact with CAO distance of 3.278 Å between the 6-CH of
the cation and the other O atom of the nitro group that is involved
in the CHAO interaction between the anions) to form 2D sheet
structure extending along the ac plane (Fig. 8). The 2D sheets prop-
phenol group (O(1)AH(1)ꢀꢀ ꢀO(2), 2.539(11) Å; and O(6)AH(6)ꢀ ꢀꢀO(7),
2.518(11) Å), it is generally expected and found that the carboxylate
group is essentially coplanar with the phenyl ring [torsion angle
C2AC3AC1AO3, 166.03°, and C9AC10AC8AO8, 175.59°]. This fea-
ture is similar to that found in salicylic acid [30], and in the previ-
ously reported structure based on 5-nsaꢁ [30]. As expected the
OAO separation is essentially in the upper limit of the documented
data [2.489–2.509 Å] [31], 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 con-
formationally [torsion angle C6AC5AN1AO4, 174.75°; and
C13AC12AN2AO9, 179.64°] compared with the reported torsion an-
gle (175.4–180°) within the 5-nsaꢁ anions [31].
In the solid state, there is consistently ionic hydrogen bond
formed between the NH+ group, and the 5-nitrosalicylate ion,
which is to be expected [32]. There also exist strong coulombic
interactions between charged cation units and the 5-nitrosalicylate
anions.
Two anions and two cations produced a tetracomponent adduct
via the NAHꢀ ꢀ ꢀO hydrogen bonds with NAO distances of
2.632(11)–3.146(12) Å. In the tetracomponent adduct the cations
were inversionally related, so did the anions. The tetracomponent
adducts were linked together via the OAHꢀ ꢀ ꢀO hydrogen bond be-
tween the phenol group of the cation and the carboxylate with
agate along the b axis direction by the
aromatic rings of the cation and the anion with CgACg distance of
3.312 Å, N– interaction between the nitro group of the anion and
the phenyl ring of the cation with NACg distance of 3.194 Å, and
O– association between the nitro unit and the phenyl ring of
p–p interaction between the
p
p
the cation with OACg distance of 3.180 Å to form 3D network
structure. The NACg distance observed in this compound is some-
what shorter than the reported NACg distance [29]. Here the adja-
cent sheets were slipped some distance from each other along the
a axis direction.
3.2.5. X-ray structure of (2-aminophenol): (5-nitrosalicylic acid)
[(HL1)+ ꢀ (5-nsaꢁ), 5-nsaꢁ = 5-nitrosalicylate] (5)
Salt 5 was prepared by reacting of an ethanol solution of 2-ami-
nophenol and 5-nitrosalicylic acid in 1:1 ratio, which crystallizes as
triclinic pale yellow crystals in the centrosymmetric space group P-
1. The asymmetric unit of 5 consists of two halves of the cations of
HL1, and two halves of 5-nitrosalicylate anions, as shown in Fig. 9.
Compound 5 is also a salt where the COOH groups of 5-nitrosalicyl-
ic acids are deprotonated. The difference between the pairs of bond
distances of O(2)AC(1) (1.253(12) Å) and O(3)AC(1) (1.270(12) Å);
O(7)AC(8) (1.290(14) Å), and O(8)AC(8) (1.217(14) Å) for the car-
boxylate are 0.017 Å, and 0.073 Å, respectively. The relative large
D
value for O(7)AC(8) (1.290(14) Å), and O(8)AC(8) (1.217(14) Å)
are due to the fact that the O(7) is involved in forming more hydro-
gen bonds that that of O(8). Because of the presence of the intra-
molecular hydrogen bond between the carboxylate group and the
Fig. 9. The structure of 5, showing the atom-numbering scheme. Displacement
ellipsoids were drawn at the 30% probability level.

252
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
3.2.6. X-ray structure of (2-amino-4-chlorophenol): (3,5-
dinitrosalicylic acid) [(HL2)+ ꢀ (3,5-dnsꢁ), 3,5-dnsꢁ = 3,5-
dinitrosalicylate], (6)
Crystallization of 2-amino-4-chlorophenol and 3,5-dinitrosali-
cylic acid in a 1:1 ratio from the mixed solvent of methanol and
ethanol gave single crystals suitable for X-ray diffraction. Structure
determination (Table 1) revealed that 2-amino-4-chlorophenol and
3,5-dinitrosalicylic acid are present in a 1:1 ratio in the molecular
complex 6. The crystal structure of 6 consists of one cation of HL2,
and one monoanion of 3,5-dinitrosalicylic acid in the asymmetric
unit (Fig. 11). Similar to the published organic salt bearing 3,5-dnsꢁ
[16], in 6 only the phenol OH groups of 3,5-dinitrosalicylic acids
are ionized by proton transfer to the L2, and the COOH group re-
mains protonized.
The CAO distance (O(4)AC(9), 1.301(3) Å) concerning the phe-
nolate is longer than the corresponding value in the proton transfer
compound bearing the 3,5-dnsꢁ in which only the phenol group
has been deprotonated [33]. The reason may be attributed to the
fact that the O4 moiety participates in forming more hydrogen
bonds (Table 3). The CAO distances (O(2)AC(7), 1.212(3),
O(3)AC(7), 1.303(3) Å) in the COOH show characteristic C@O, and
CAO distances which are also confirming the reliability of adding
H atoms experimentally by different electron density onto O atoms
as mentioned above. The torsion angles O6AN2AC10AC9, and
O7AN3AC12AC13 are ꢁ179.0(2)°, and 156.5(3)°, respectively. In
this regard, both nitro groups are nearly in the same plane as the
phenyl ring of the anion, yet the 3-nitro group (O6AN2AO5) devi-
ates somewhat less from the plane than the 5-nitro group
(O7AN3AO8), which is different from the published results [33].
The water molecule was bonded to the cation via one NAHꢀ ꢀ ꢀO
hydrogen bond (between the water molecule (acceptor) and the
aminium cation with NAO distance of 2.818(3) Å (N(1)AH(1A)ꢀ ꢀ ꢀ
O(9)#4, 2.818(3) Å, 173.1°), and one CHAO contact (between the
3-CH of the cation and the Ow atom with CAO distance of
3.333 Å) to generated a hydrogen bonded ring with graph set
descriptor of R12ð6Þ. There also exists intramolecular OAHꢀ ꢀ ꢀO
hydrogen bond with graph set of S11ð6Þ which is between the COOH
unit and the phenolate in the anion with OAO separation of
2.424(3) Å. The cation attached with the water molecule was
linked with the anion via the OAHꢀ ꢀ ꢀO hydrogen bond between
the phenol group of the cation and the carbonyl unit of the anion
Fig. 10. 2D sheet structure of 5 which is extending parallel to the bc plane.
OAO distance of 2.624(9) Å to form 1D chain running parallel to
the c axis direction. The chains were further joined together by
the CHAO association between the phenyl CH of the anion and
the phenol group of the anion belonging to the neighboring chains
with CAO distance of 3.466 Å to form 2D sheet extending parallel
to the bc plane (Fig. 10), herein the cations bonded to the sheet
were protruded from the sheet plane. Two adjacent sheets were
joined together via the same face of the sheet by the NAHꢀ ꢀ ꢀO (be-
tween the aminium cation and the carboxylate with NAO distance
of 3.026(11) Å, and between the NHþ3 and the phenol moiety with
NAO distance of 2.954 Å), and O–p (between the nitro group and
the phenyl ring of the anion with OACg distance of 3.105 Å) inter-
actions to form 2D double sheet structure. The double sheets were
further propagated along the a axis direction via the CHAO contact
between the 5-, and 6-CH of the cation and the nitro group of the
anion belonging to two different sheets of the double sheet with
CAO distances of 3.243–3.419 Å to form 3D layer network struc-
ture. Herein the adjacent double sheets were slipped some dis-
tance from each other along their extending direction.
Fig. 11. The structure of 6, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
253
Fig. 12. 1D chain structure of 6 built from ClACl bond, and OAHꢀ ꢀ ꢀO interactions which is running along the b axis direction.
Fig. 13. The structure of 7, showing the atom-numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
Fig. 14. 2D sheet structure of 7 that is extending on the ab plane.
with OAO separation of 2.609(3) Å, and CHAO association between
the 6-CH of the cation and the same carbonyl group with CAO dis-
tance of 3.222 Å to form a tricomponent adduct. The tricomponent
adducts were linked together via the CHAO interaction between
the nitro group and the aromatic CH of the cation with CAO dis-
tances in the range of 3.282–3.437 Å to form a hexacomponent ad-
duct. In the hexacomponent adduct there existed an inversion
centre which is located at the middle point of the two 5-nitro
groups in the hexacomponent adduct. The hexacomponent adducts
were combined together via the ClACl bond between the cations
and OAHꢀ ꢀ ꢀO hydrogen bond between the water molecule and
the nitro group with OAO separation of 2.894(3) Å (O(9)AH(9C)ꢀ ꢀ ꢀ
O(5), 2.894(3) Å, 152.8°) to form a 1D chain running along the b
axis direction (Fig. 12). Here the ClACl separation is 3.380 Å, which
is within the range of a ClACl bond [34]. The 1D chains were
3.069 Å, and p–p association between the phenyl moieties of the
cation and the anion with CgACg distances of ca. 3.246–3.382 Å
to form 2D sheet extending parallel to the ab plane. The sheets
were further stacked along the c axis direction to form 3D ABAB
layer network structure through the intersheet NAHꢀ ꢀ ꢀO (N(1)A
H(1C)ꢀ ꢀ ꢀO(3)#1, 2.989(3) Å, 132.1°) hydrogen bond between the
aminium cation and the phenol group with NAO distance of
2.989(3) Å, and OAHꢀ ꢀ ꢀO (O(9)AH(9D)ꢀ ꢀ ꢀO(4)#1, 2.724(2) Å,
152.1°) hydrogen bond between the water molecule and the phe-
nolate with OAO distance of 2.724(2) Å. It is worthy to mention
that the chains at adjacent sheets made an angle of ca 60° with
each other. The first sheet layer was parallel to the third sheet
layer, so did the second sheet layer and the fourth sheet layer.
3.2.7. X-ray structure of (2-amino-4-chlorophenol): (fumaric acid)0.5
further stacked along the
(N(1)AH(1C)ꢀ ꢀ ꢀO(4), 3.069(3) Å, 123.1°) hydrogen bond between
a
axis direction via the NAHꢀꢀꢀO
[(HL2)+ ꢀ (fum2ꢁ
)
0.5, fumꢁ = fumarate] (7)
Similar to the above compounds, compound 7 was prepared by
the aminium cation and the phenolate with NAO distance of
reaction of fumaric acid and 2-amino-4-chlorophenol in 1:1 ratio,

254
S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
which crystallizes as monoclinic colorless crystals in the centro-
symmetric space group P2(1)/c. The asymmetric unit of 7 consists
of one cation of HL2, and half a dianion of fumarate, as shown in
Fig. 13. The C8AC8#1 bond distance (1.282(5) Å) is for a simple
C@C double bond. The CAO distances (O(2)AC(7), 1.255(3) Å;
and O(3)AC(7), 1.264(3) Å) clearly indicate that the acid moieties
in the compound are dianions when it formed hydrogen bonds
with the aminium moiety.
Acknowledgements
We gratefully acknowledge the financial support of the Educa-
tion Office Foundation of Zhejiang Province (Project No.
Y201017321) and the financial support of the Xinmiao project of
the Education Office Foundation of Zhejiang Province (Project No.
2009FK63).
At each cation there was attached a water molecule through the
NAHꢀ ꢀ ꢀO hydrogen bond between the aminium group and the Ow
atom with NAO distance of 2.817(3) Å, and CHAO association pro-
duced by the 3-CH of the cation with CAO distance of 3.393 Å. Two
cations attached with the water molecules were bonded to one an-
ion via the OAHꢀ ꢀ ꢀO hydrogen bond between the phenol group and
the carboxylate with OAO distance of 2.668(2) Å to form a penta-
component adduct. In the pentacomponent heteroadduct there is
an inversion centre located at the middle point of the olefinic
group in the fumarate. There are two kinds of pentacomponent ad-
duct, although the component is the same, the difference is that
the two kinds of pentacomponent adduct made an angle of ca
60° with each other. The same kinds of adjacent parallel pentacom-
ponent adducts were linked together by the water molecule
through the OAHꢀ ꢀ ꢀO hydrogen bond between the water molecule
and the carboxylate with OAO separation of 2.838(3) Å. And the
two kinds of different pentacomponent adducts were linked to-
gether via the ClAO contact with ClAO distance of 3.118 Å to form
2D sheet extending on the ab plane (Fig. 14). The ClAO separation
is longer than that in 5-chloro-1,2-dimethyl-4-nitro-1H-imidazole
(2.899(1) Å), yet it is shorter than the values (3.285, and 3.498 Å) in
2-chloro-1-methyl-4-nitro-1H-imidazole [35]. The 2D sheets were
further stacked along the c axis direction via NAHꢀ ꢀ ꢀO (between
the aminium cation and the carboxylate with NAO distances of
2.812(3)–2.828(3) Å), and OAHꢀ ꢀ ꢀO (between the water molecule
and the carboxylate with OAO distance of 2.908(3) Å) interactions
to form 3D network structure.
Appendix A. Supplementary material
Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic data center, CCDC
Nos. 851937 for 1, 835102 for 2, 851605 for 3, 851594 for 4,
835068 for 5, 851605 for 6, and, 816393 for 7. Copies of this infor-
mation may be obtained free of charge from the +44 (1223)336 033
or Email: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.ca-
m.ac.uk. Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/
j.molstruc.2013.01.012.
References
[1] M. Khurram, N. Qureshi, M.D. Smith, Chem. Commun. (2006) 5006.
[2] R. Shukla, S.V. Lindeman, R. Rathore, Chem. Commun. (2007) 3717.
[3] C.Q. Wan, X.D. Chen, T.C.W. Mak, CrystEngComm 10 (2008) 475.
[4] G.M. Whitesides, E.E. Simanek, J.P. Mathias, C.T. Seto, D. Chin, M. Mammen,
D.M. Gordon, Acc. Chem. Res. 28 (1995) 37 (and references therein).
[5] S. Aitipamula, A. Nangia, Chem. Eur. J. 11 (2005) 6727.
[6] K.K. Arora, V.R. Pedireddi, J. Org. Chem. 68 (2003) 9177.
[7] B.R. Bhogala, A. Nangia, Cryst. Growth Des. 3 (2003) 547.
[8] C.B. Aakeröy, D.J. Salmon, CrystEngComm 7 (2005) 439.
[9] C.M. Grossel, A.N. Dwyer, M.B. Hursthouse, J.B. Orton, CrystEngComm 8 (2006)
123.
[10] S. Varughese, V.R. Pedireddi, Chem. Eur. J. 12 (2006) 1597.
[11] M. Du, Z.H. Zhang, X.J. Zhao, H. Cai, Cryst. Growth Des. 6 (2006) 114.
[12] A.D. Bond, Chem. Commun. (2003) 250.
[13] B.R. Bhogala, A. Nangia, New J. Chem. 32 (2008) 800.
[14] (a) P. Metrangolo, H. Neukirch, T. Pilati, G. Resnati, Acc. Chem. Res. 47 (2005)
386;
(b) T.R. Shattock, K.K. Arora, P. Vishweshwar, M.J. Zaworotko, Cryst. Growth
Des. 8 (2008) 4533;
(c) K. Biradha, G. Mahata, Cryst. Growth Des. 5 (2005) 61;
(d) B.Q. Ma, P. Coppens, Chem. Commun. (2003) 504;
(e) A.M. Beatty, C.M. Schneider, A.E. Simpson, J.L. Zaher, CrystEngComm 4
(2002) 282;
4. Conclusion
Seven hybrid organic acid–base crystals have been prepared
and their crystal structures determined. The different hydrogen
bond interaction modes of the acidic components and the 2-ami-
nophenol derivatives lead to a wide range of different structures
such as 3D network structure, 3D layer network structure, and
3D ABAB layer structure.
Of the seven organic acid–base adducts six examples (1, 3, 4, 5,
6, and 7) involve proton transfer from the acidic units to the amine
group of the 2-aminophenol derivatives to form a monocation.
Compound 2 is a cocrystal. Here this phenomenon may be ex-
plained by the rule ‘‘strongest donor to strongest acceptor’’, for
the carboxylic acids present in 1–7, the p-nitrobenzoic acid in 2
has the relatively larger pKa than other acidic components dis-
cussed in this manuscript.
(f) A. Ballabh, D.R. Trivedi, P. Dastidar, E. Suresh, CrystEngComm 4 (2002) 135.
[15] (a) A. Dey, G.R. Desiraju, R. Mondal, J.A.K. Howard, Chem. Commun. (2004)
2528;
(b) A. Dey, N.N. Pati, G.R. Desiraju, CrystEngComm 8 (2006) 751;
(c) A. Dey, M.T. Kirchner, V.R. Vangala, G.R. Desiraju, R. Mondal, J.A.K. Howard,
J. Am. Chem. Soc. 127 (2005) 10545;
(d) F.H. Allen, V.J. Hoy, J.A.K. Howard, V.R. Thalladi, G.R. Desiraju, C.C. Wilson,
G.J. McIntyre, J. Am. Chem. Soc. 119 (1997) 3477.
[16] G. Smith, U.D. Wermuth, P.C. Healy, J.M. White, J. Chem. Crystallogr. 41 (2011)
1649.
[17] R.H. Blessing, Acta Crystallogr. A51 (1995) 33.
[18] G.M. Sheldrick, SADABS Siemens Area Detector Absorption Correction,
University of Göttingen, Göttingen, Germany, 1996.
[19] SHELXTL-PC, version 5.03, Siemens Analytical Instruments: Madison, WI.
[20] M. Lazzarrotto, E.E. Castellano, F.F. Nachtigall, J. Chem. Crystallogr. 37 (2007)
699.
[21] (a) T. Kagawa, R. Kawai, S. Kashino, M. Haisa, Acta Crystallogr. B32 (1976)
3171;
This study has demonstrated that the NAHꢀ ꢀ ꢀO/OAHꢀ ꢀ ꢀO hydro-
gen bonds are the primary intermolecular force in a family of struc-
tures containing the OHꢀ ꢀ ꢀ2-aminophenol synthons. Except the
classical hydrogen bonding interactions, the secondary propagat-
ing interactions also made significant contribution to the structure
extension. The seven salts/cocrystal all possess weak CAHꢀ ꢀ ꢀO
(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;
(g) I. Majerz, Z. Malarski, L. Sobczyk, Chem. Phys. Lett. 274 (1997) 361.
[22] J.D. Korp, I. Bernal, L. Aven, J.L. Mills, J. Cryst. Mol. Struct. 11 (1981) 117.
[23] J. Janczak, G.J. Perpétuo, Solid State Sci. 11 (2009) 1576.
[24] C. Muthamizhchelvan, K. Saminathan, J. Fraanje, R. Peschar, K. Sivakumar, X-
ray Struct. Anal. Online 21 (2005) x61.
associations. There are also
and 6. The O–
sesses additional N–
p
–
p
associations in compounds 4,
interactions were found in 3, 4, and 5, while 4 pos-
interaction. Salt 6 bears the ClACl bond.
p
p
[25] J. Bernstein, R.E. Davis, L. Shimoni, N.L. Chang, Angew. Chem. Int. Ed. 34 (1995)
1555.
[26] S. Ashfaquzzaman, A.K. Pant, Acta Cryst. B35 (1979) 1394.
[27] N. Schultheiss, K. Lorimer, S. Wolfe, J. Desper, CrystEngComm 12 (2010) 742.
[28] D. Dutta, A.D. Jana, A. Ray, J. Marek, M. Ali, Indian J. Chem. 47A (2008) 1656.
In conclusion, we have shown that 3D structures can be con-
structed by the synergic interactions such as classical hydrogen
bond (NAHꢀ ꢀ ꢀO/OAHꢀ ꢀ ꢀO), CHAO,
p–p, O–p, N–p, ClACl, and ClAO
interactions between discrete components.

S. Jin, D. Wang / Journal of Molecular Structure 1037 (2013) 242–255
255
[29] G. Orona, V. Molinar, F.R. Fronczek, R. Isovitsch, Acta Cryst. E67 (2011) o2505.
[30] M. Sundaralingam, L.H. Jensen, Acta Crystallogr. 18 (1965) 1053.
[31] G. Simith, A.W. Hartono, U.D. Wermuth, P.C. Healy, J.M. White, A.D. Rae, Aust. J.
Chem. 58 (2005) 47.
[33] F.V. González, A. Jain, S. Rodríguez, J.A. Sáez, C. Vicent, G. Peris, J. Org. Chem. 75
(2010) 5888.
[34] F.F. Awwadi, R.D. Willett, B. Twamley, Cryst. Growth Des. 7 (2007) 624.
[35] M. Kubicki, P. Wagner, Acta Cryst. C63 (2007) o454.
[32] M. Felloni, A.J. Blake, P. Hubberstey, C. Wilson, M. Schröder, CrystEngComm 4
(2002) 483.