Single-crystal and molecular structures of six hydrogen-bonding 3D supramolecular salts from 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and acidic components

Article abstract of DOI:10.1016/j.molstruc.2018.10.080

Cocrystallization experiments of the commonly available 2-aminobenzoic acid/3-aminobenzoic acid/4-aminobenzoic acid, with a series of organic acids gave a total of six anhydrous molecular salts. The structures of these salts were subsequently characterized by IR, EA, and XRD analysis technique, and the melting points of all salts were also reported. In the six salts, the NH₂ of the aminobenzoic acids are protonated when the organic acids are deprotonated, and the crystal packing is interpreted in terms of strong N–H?O H-bonds from the NH₃ ⁺ and deprotonated acidic groups. Except the N–H?O H-bond, the O–H?O H-bonds were also found at 1–6. The salts of the aryl sulfonates exhibited the N–H?S H-bonds, and salt 4 has the additional O–H?S H-bond. In these structures homo or hetero supramolecular synthons or both were produced, making R₁ ²(3), R₁ ²(5), R₁ ²(7), R₂ ¹(6), R₂ ²(4), R₂ ²(5), R₂ ²(8), R₂ ²(12), R₂ ²(16), R₂ ³(6), R₃ ²(7), R₃ ²(9), R₃ ³(8), R₃ ³(9), R₃ ³(10), R₄ ²(8), R₄ ²(18), R₄ ²(14), R₄ ⁴(12), R₄ ⁴(22), R₆ ⁵(18), and R₆ ⁶(26) rings which could have important function in the formation and stabilization of the crystals. But not all of them were appeared repeatedly, as most of them occurred only in some structures. Nevertheless R₄ ²(8), R₄ ³(10) and R₄ ⁴(12) usually observed in organic solids of organic acids with amine, were again shown to be involved in most of these H-bonding networks. Further inspection into the crystal packing of the salts indicated that a large variety of different secondary interactions were also existed in 1–6, which contribute to the stabilization and expansion of the total 3D framework structures.

Full text of DOI:10.1016/j.molstruc.2018.10.080

Accepted Manuscript
Single-crystal and molecular structures of six hydrogen-bonding 3D supramolecular
salts from 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and
acidic components
Yuan Lu, Weiqiang Xu, Heli Sun, Jianye Jin, Hui Liu, Shouwen Jin, Daqi Wang, Ming
Guo
PII:
S0022-2860(18)31280-8
DOI:
https://doi.org/10.1016/j.molstruc.2018.10.080
MOLSTR 25809
Reference:
To appear in: Journal of Molecular Structure
Received Date: 2 January 2018
Revised Date: 23 October 2018
Accepted Date: 25 October 2018
Please cite this article as: Y. Lu, W. Xu, H. Sun, J. Jin, H. Liu, S. Jin, D. Wang, M. Guo, Single-crystal
and molecular structures of six hydrogen-bonding 3D supramolecular salts from 2-aminobenzoic acid, 3-
aminobenzoic acid, 4-aminobenzoic acid, and acidic components, Journal of Molecular Structure (2018),
doi: https://doi.org/10.1016/j.molstruc.2018.10.080.
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Single-crystal and Molecular Structures of Six Hydrogen-Bonding 3D
Supramolecular Salts from 2-aminobenzoic Acid, 3-aminobenzoic Acid,
4-aminobenzoic Acid, and Acidic Components
Yuan Lua, Weiqiang Xua,b, Heli Suna, Jianye Jina, Hui Liua,b, Shouwen Jina,b*, Daqi
Wangc, and Ming Guob
aZheJiang A & F University, Lin'An 311300, P. R. China. *E-mail: jinsw@zafu.edu.cn
bKey Laboratory of Chemical Utilization of Forestry Biomass of Zhejiang Province
Zhejiang A & F University, Zhejiang Province, 311300, China
cDepartment of Chemical Engineering, Liaocheng University, 252059, China.
Abstract:
Cocrystallization experiments of the commonly available 2-aminobenzoic
acid/3-aminobenzoic acid/4-aminobenzoic acid, with a series of organic acids gave a
total of six anhydrous molecular salts. The structures of these salts were subsequently
characterized by IR, EA, and XRD analysis technique, and the melting points of all
salts were also reported. In the six salts, the NH2 of the aminobenzoic acids are
protonated when the organic acids are deprotonated, and the crystal packing is
+
interpreted in terms of strong N-H⋯O H-bonds from the NH3 and deprotonated acidic
groups. Except the N-H⋯O H-bond, the O-H···O H-bonds were also found at 1-6. The
salts of the aryl sulfonates exhibited the N-H···S H-bonds, and salt 4 has the
additional O-H···S H-bond. In these structures homo or hetero supramolecular
2
2
2
1
2
2
synthons or both were produced, making R1 (3), R1 (5), R1 (7), R2 (6), R2 (4), R2 (5),
2
2
2
3
2
2
3
3
3
2
2
R2 (8), R2 (12), R2 (16), R2 (6), R3 (7), R3 (9), R3 (8), R3 (9), R3 (10), R4 (8), R4 (18),
2
4
4
5
6
R4 (14), R4 (12), R4 (22), R6 (18), and R6 (26) rings which could have important
function in the formation and stabilization of the crystals. But not all of them were
appeared repeatedly, as most of them occurred only in some structures. Nevertheless
2
3
4
R4 (8), R4 (10) and R4 (12) usually observed in organic solids of organic acids with
amine, were again shown to be involved in most of these H-bonding networks.
Further inspection into the crystal packing of the salts indicated that a large variety of
different secondary interactions were also existed in 1-6, which contribute to the

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stabilization and expansion of the total 3D framework structures.
Keywords: Supramolecular salts; Crystal structures; Hydrogen bonding;
Aminobenzoic acids.
Introduction
H-bond is one of the most important non-covalent interactions, and it has very
important roles in the area of molecular recognition, crystal engineering,
supramolecular chemistry, materials science, and biological systems [1]. There were
many different types of H-bonds including conventional and unconventional H-bond
in the literatures [2], in which short strong H-bonds were also frequently found [3-5].
Hydrogen bonding is also an important driving force in the organic salts
formation in terms of its short lengths, high selectivity and direction, and salt
formation is often used to tailor the biopharmaceutical properties including the
solubility, stability and hygroscopicity [6]. Up to date there are documented many
fascinating hydrogen bonded topological structures from one dimensional chain to
three dimensional frameworks [7]. The organic acid bears the nice donor-acceptor
units for the crystal engineering [8], and they self-assemble in the solid by
homosynthons exhibiting many different motifs [9].
There have been of great interest to study the robust and directional recognition
mode from the organic acids and the basic components of aromatic amine, aliphatic
amine and pyridyl derivatives [10]. In addition to the acidic groups, the NO2, CH3, Cl,
and aromatic moieties are all excellent groups in building the organic crystalline
solids via various non-covalent bonds [11], thus we chose some organic acids bearing
the above mentioned groups.
The amino benzoic acid contains equal number of the electron withdrawing
-CO2H and the electron giving -NH2 connected by the conjugated aryl ring, which can
exhibit more complex nonbonding associations as it interacted with the organic acids.
To the best of our knowledge, there are a few papers involving the organic acid-base
adducts in which the amino benzoic acid functioned as the H-acceptor in proton

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transfer compounds [12, 13].
Recently, we have focused our continuing efforts on studying the hydrogen
bonding, π-stacking, and halogen bonding interactions concerning the N-containing
bronsted bases [14], herein we will hope to report the synthesis and structures of six
organic salts based on 2-aminobenzoic acid (L1), 4-aminobenzoic acid (L2),
3-aminobenzoic acid (L3) and the corresponding organic acids (Scheme 1). The six
organic salts are (2-aminobenzoic acid) : (benzenesulfonic acid) (1) [(HL1)+ · (bzs-),
bzs- = benzenesulfonate], (2-aminobenzoic acid) : (p-toluenesulfonic acid) (2)
[(HL1)+ · (pts-)], (4-aminobenzoic acid) : (p-toluenesulfonic acid) (3) [(HL2)+ · (pts-),
pts- = p-toluenesulfonate], (2-aminobenzoic acid)2 : (1, 5-naphthalenedisulfonic acid)
2+
(4) [(HL1)2 · (nds2-), nds2- = 1, 5-naphthalenedisulfonate], (4-aminobenzoic acid) :
(3-nitrophthalic acid) (5) [(HL2)+ · (Hnpa-), Hnpa- = 3-nitrohydrogenphthalate], and
(3-aminobenzoic acid) : (trichloroacetic acid) (6) [(HL3)+ · (tca-), tca- =
trichloroacetate], respectively (Scheme 2). The supramolecular synthons of 1-6 were
listed at Scheme 3.
NH2
H2N
O
O
O
NH2
HO
HO
HO
3-aminobenzoic acid
4-aminobenzoic acid
2-aminobenzoic acid
O
OH
O
O
S
S
O
S
O
OH
HO
S
OH
O
O
O
p-toluenesulfonic acid
benzenesulfonic acid
1, 5-naphthalenedisulfonic acid
O2N
O
HO
Cl
O
HO
O
Cl
Cl
OH
trichloroacetic acid
3-nitrophthalic acid
Scheme 1 Molecular structures of the components in 1-6.

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Scheme 2 The organic salts 1-6 in this work.

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Scheme 3 Supramolecular synthons in 1-6.
Experimental section
Materials and Physical Measurements
The chemicals and solvents in this work were analytical grade commercial
products and were used without further purification. FT-IR spectra in 4000-400 cm-1
were taken on a Mattson Alpha-Centauri spectrometer from KBr pellets, and the IR
bands were marked as strong (s), medium (m), and weak (w) at the preparation part.
The C, H, N, and S concentrations were recorded microanalytically on a Perkin-Elmer
elemental analyzer with Model 2400II, and the melting points of the salts were
performed on an XT-4 thermal instrument without correction.
Synthesis of salts 1-6
a. (2-aminobenzoic acid) : (benzenesulfonic acid) [(HL1)+ · (bzs-)] (1)
To a methanol solution (12 mL) of 2-aminobenzoic acid (38 mg, 0.2 mmol) was
added 80% benzenesulfonic acid (39.5 mg, 0.2 mmol) with constant stirring for 15
minutes. The solution was then filtered into a test tube and allowed for slow
evaporation at room temperature; colorless crystals were obtained two weeks later.
The crystals were filtered out and dried to give [(HL1)+ · (bzs-)] (1), the yield was 46
mg (77.89%). m. p. 94-96 °C. Anal. Calcd for C13H13NO5S (295.30): C, 52.83; H,
4.40; N, 4.74; S, 10.84. Found: C, 52.70; H, 4.28; N, 4.66; S, 10.76. FT-IR (KBr disc,
cm-1): 3514m(br, OH), 3420m(νas(NH)), 3335w(νs(NH)), 3260m, 3156m, 3044m,
2950m, 2866m, 1666s(ν(C=O)), 1612m, 1568m, 1525m, 1480m, 1438m, 1396m,
1355m, 1313m 1275s(ν(C-O)), 1234m, 1196m, 1154m, 1116m, 1072m, 1030m,

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988m, 948m, 905m, 863m, 820m, 777m, 738m, 696m, 654m, 612m, 605m.
b. (4-aminobenzoic acid) : (p-toluenesulfonic acid) [(HL2)+ · (pts-)] (2)
To a methanol solution (18 mL) of 4-aminobenzoic acid (38 mg, 0.2 mmol) was
added p-toluenesulfonic acid monohydrate (38 mg, 0.2 mmol) with constant stirring
for 15 minutes. The solution was then filtered into a test tube and allowed for slow
evaporation at room temperature; colorless crystals were obtained 15 days later. The
crystals were filtered out and dried to give [(HL2)+ · (pts-)] (2), the yield was 52 mg
(84.05%). m. p. 118-120°C. Anal. Calcd for C14H15NO5S (309.33): C, 54.31; H, 4.85;
N, 4.52; S, 10.34. Found: C, 54.22; H, 4.78; N, 4.41; S, 10.26. FT-IR (KBr disc, cm-1):
3566(br, OH), 3472s(νas(NH)), 3345s(νs(NH)), 3256m, 3158m, 3062m, 2966m,
2868m, 1676s(ν(C=O)), 1566m, 1524m, 1482m, 1430m, 1381m, 1340m,
1298s(ν(C-O)), 1256m, 1218m, 1185m, 1140m, 1073m, 1007m, 965m, 923m, 880m,
838m, 796m, 754m, 710m, 666m, 620m, 602m.
c. (2-aminobenzoic acid) : (p-toluenesulfonic acid) [(HL1)+ · (pts-)] (3)
To a methanol solution (14 mL) of 2-aminobenzoic acid (38 mg, 0.2 mmol) was
added p-toluenesulfonic acid monohydrate (38 mg, 0.2 mmol) with constant stirring
for 15 minutes. The solution was then filtered into a test tube and allowed for slow
evaporation at room temperature; colorless crystals were obtained 10 days later. The
crystals were filtered out and dried to give [(HL1)+ · (pts-)] (3), the yield was 50 mg
(80.82%). m. p. 98-100 °C. Anal. Calcd for C14H15NO5S (309.33): C, 54.31; H, 4.85;
N, 4.52; S, 10.34. Found: C, 54.26; H, 4.77; N, 4.46; S, 10.29. FT-IR (KBr disc, cm-1):
3549(br, OH), 3437m(νas(NH)), 3340w(νs(NH)), 3256m, 3032m, 2960m, 2874w,
1658s(ν(C=O)), 1606m, 1564m, 1524m, 1484m, 1442m, 1400m, 1358m, 1316m
1280s(ν(C-O)), 1236m, 1190m, 1148m, 1106m, 1066m, 1028m, 984m, 943m, 902m,
858m, 816m, 775m, 732m, 686m, 643m, 618m, 600m.
2+
d. (2-aminobenzoic acid)2 : (1, 5-naphthalenedisulfonic acid) [(HL1)2 · (nds2-)]
(4)
To a methanol solution (30 mL) of 2-aminobenzoic acid (38 mg, 0.2 mmol) was

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added 1, 5-naphthalenedisulfonic acid tetrahydrate (72 mg, 0.2 mmol) with constant
stirring for 15 minutes. The solution was then filtered into a test tube and allowed for
slow evaporation at room temperature; colorless crystals were obtained 22 days later.
2+
The crystals were filtered out and dried to give [(HL1)2 · (nds2-)] (4), the yield was
46 mg, (81.77% based on L1). m. p. 184-186 °C. Anal. Calcd for C24H22N2O10S2
(562.56): C, 51.19; H, 3.91; N, 4.98; S, 11.38. Found: C, 51.12; H, 3.84; N, 4.90; S,
11.32. FT-IR (KBr disc, cm-1): 3589s(ν(OH)), 3451m(νas(NH)), 3371w(νs(NH)),
3268m, 3174m, 3012m, 2998w, 2950w, 2860m, 1672s(ν(C=O)), 1600m, 1556m,
1514m, 1472m, 1430m, 1386m, 1345m, 1302s(ν(C-O)), 1258m, 1215m, 1169m,
1127m, 1084m, 1041m, 998m, 956m, 915m, 874m, 832m, 788m, 743m, 696m, 653m,
624m, 605m.
e. (4-aminobenzoic acid) : (3-nitrophthalic acid) [(HL2)+ · (Hnpa-)] (5)
To a methanol solution (20 mL) of 4-aminobenzoic acid (38 mg, 0.2 mmol) was
added 3-nitrophthalic acid (42.2 mg, 0.2 mmol) with constant stirring for 15 minutes.
The solution was then filtered into a test tube and allowed for slow evaporation at
room temperature; colorless crystals were obtained 16 days later. The crystals were
filtered out and dried to give [(HL2)+ · (Hnpa-)] (5), the yield was 58 mg (83.27%). m.
p. 201-202°C. Anal. Calcd for C15H12N2O8 (348.27): C, 51.68; H, 3.44; N, 8.04.
Found: C, 51.58; H, 3.37; N, 7.95. FT-IR (KBr disc, cm-1): 3606s(ν(OH)),
3465s(νas(NH)), 3345s(νs(NH)), 3252m, 3186m, 3144m, 3094m, 2984m, 2864m,
1702s(ν(C=O)), 1608s(νas(COO-)), 1566m, 1524s(νas(NO2)), 1482m, 1440m,
1398s(νs(COO-)), 1356m, 1315s(νs(NO2)), 1282s(ν(C-O)), 1238m, 1196m, 1152m,
1110m, 1066m, 1024m, 980m, 936m, 894m, 850m, 808m, 766m, 725m, 682m, 638m,
604m.
f. (3-aminobenzoic acid) : (trichloroacetic acid) [(HL3)+ · (tca-)] (6)
To a methanol solution (12 mL) of 3-aminobenzoic acid (38 mg, 0.2 mmol) was
added trichloroacetic acid (32.6 mg, 0.2 mmol) with constant stirring for 15 minutes.
The solution was then filtered into a test tube and allowed for slow evaporation at

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room temperature; colorless crystals were obtained two weeks later. The crystals were
filtered out and dried to give [(HL3)+ · (tca-)] (6), the yield was 44 mg, (73.21%). m. p.
128-130 °C. Anal. Calcd for C9H8Cl3NO4 (300.51): C, 35.94; H, 2.66; N, 4.66. Found:
C, 35.82; H, 2.55; N, 4.58. FT-IR (KBr disc, cm-1): 3520s(ν(OH)), 3438m(νas(NH)),
3350w(νs(NH)), 3264m, 3170m, 2934m, 2855w, 2798w, 1664s(ν(C=O)),
1612s(νas(COO-)), 1568m, 1525m, 1484m, 1440m, 1397s(νs(COO-)), 1360m, 1322m,
1280s(ν(C-O)), 1237m, 1195m, 1152m, 1108m, 1066m, 1023m, 980m, 935m, 890m,
849m, 805m, 763m, 722m, 680m, 640m, 612m.
X-ray Crystallography
SCXRD data of 1-6 were collected on a Bruker SMART 1000 CCD
diffractometer equipped with the graphite-monochromated Mo-Kα radiation (λ =
0.71073 Å) operating at 50 kV and 40 mA. Data collections and reductions were
carried out by the SMART and SAINT softwares [15]. The structures were solved
directly, and the non-Hs were refined anisotropically via full-matrix least squares on
F2 with SHELXL program of the SHELXTL package [16]. All Hs were placed in
geometrically calculated positions and included in the refinement in a riding-model
approximation. All of the associated crystallographic data are shown in Table 1,
selected bond lengths and angles in Table 2, and the relevant H-bond geometrical
parameters in Table 3.
Table 1. should be inserted here.
Table 2. should be inserted here.
Results and Discussion
Preparation and General Characterization
Salts 1-6 were prepared by the same method of mixing the organic acids with the
aminobenzoic acid at 1:1 in CH3OH, and the crystals were obtained at ambient
conditions via the evaporating technique. All salts are not humidity sensitive. The
elemental analysis results of the six salts support their compositions. The infrared
spectra of the six compounds fit with their chemical formulas determined by
elemental analysis and XRD analysis. The strong and broad bands at 3606-3335 cm-1

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in the IR spectra of the six compounds are attributed to the N-H/O-H stretching
participated in H-bonds. The moderate intensity bands in 1500-1630 cm-1 and
600-750 cm-1 are from the aryl ring stretching and bending, respectively. The CO2H
in the aminobenzoic acid shows both ν(C=O) and ν(C-O) in 1658-1702, and
1275-1302 cm-1. IR is also very useful for the diagnosis of the H-transfer compounds
-
on the carboxylic acids [17]. The existence of the CO2 in 5 and 6 is elucidated by the
strong asymmetrical (1608-1612 cm-1) and symmetrical (1397-1398 cm-1) stretching
frequencies [18].
Table 3. should be inserted here.
Structural descriptions
Molecular and supramolecular structure of (2-aminobenzoic acid) :
(benzenesulfonic acid) [(HL1)+ · (bzs-)] (1)
Fig. 1 should be inserted here.
The compound 1 with the composition [(HL1)+ · (bzs-)] obtained by reacting
equal mol 2-aminobenzoic acid and benzenesulfonic acid, crystallizes as triclinic
colorless crystals in the space group P-1 with Z = 2, and the asymmetric unit consists
of one HL1, and one bzs- (Fig. 1s). There is one ion pair with no solvent molecules
accompanied in 1. The C9-C13 and the respective H attached to these C were all
disordered over two sites with equal occupancies.
The compound 1 is classified as a salt in which SO3H of the benzenesulfonic acid
is absolutely ionized by H transfer to the NH2 of the L1, which is also supported by
the S-O bonds (1.454(2)-1.463(2) Å) at S1-O5-O4-O3. In addition, the S-O bond
lengths are comparable to those (1.4474 (13)-1.4685(13) Å) in other benzenesulfonate
salt [19]. The C-N bond (N(1)-C(3), 1.465(4) Å) is significantly larger than the
corresponding C-N bond (1.3732 (16) Å) at the 2-aminobenzoic acid with the NH2
unprotonated [20]. The lengthening of the C-N bond further verified our right
assignment of the cation. Protonation of the N1 was reflected in the C(4)-C(3)-N(1)
and C(2)-C(3)-N(1) angles (118.6(3)º - 119.8(2)º), this also occurs in other salt of
amino-benzene derivative [21]. The torsion angle O(2)-C(1)-C(2)-C(3) (23.9(5)º)
clearly shows the coplanarity of the CO2H and the benzene ring. The C-O bonds at the

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O1-C1-O2 were 1.207(4) Å (O(1)-C(1)) and 1.327(4) Å (O(2)-C(1)), respectively,
supporting the presence of the CO2H.
+
A bzs- was bonded to a HL1 via the N-H···O H-bond between one H of the NH3
-
and one O at the SO3 with N-O distance of 2.816(3) Å, and N-H···S hydrogen bond
+
-
from the same H of the NH3 and the S at the SO3 with N-S distance of 3.713(3) Å to
show a heteroadduct. At the HL1 there established the intramolecular N-H···O
+
H-bond from the NH3 and the C=O of the CO2H with N-O distance of 2.725(3) Å
exhibiting the S(6) type ring defined by Bernstein [22], which was also occurred in
2-carboxyanilinium nitrate [12b].
Two heteroadducts were held together by the O-H···O H-bond from the CO2H
-
and the second O of the SO3 with O-O distance of 2.693(3) Å, and N-H···O H-bond
+
between the second H of the NH3 and the C=O at the CO2H with N-O distance of
2.909(3) Å to give a tetracomponent aggregate. At the a-axis the tetracomponent
aggregates were linked together via the N-H···O H-bond between the second H of the
+
-
NH3 and the third O at the SO3 with N-O distance of 2.912(4) Å, N-H···O H-bond
+
-
from the third H of the NH3 and the second O at the SO3 with N-O distance of
-
2.828(3) Å, O-π contact from the third O at the SO3 and the aryl ring of the cation
with O-Cg separation of 3.148 Å, and C-π contact from the carboxyl C and the aryl
nucleus of the cation with C-Cg separation of 3.356 Å to give 1D chain. In this case
the O-Cg separation is close to the archived data (3.12 Å) [23]. In the ab plane the 1D
chains were bundled into 2D sheet (Fig. 1) by the CH-O association from the para-H
-
of the HL1 and the first O of the SO3 with C-O distance of 3.383 Å. The sheet had
2
2
3
2
2
4
the I R1 (3), II R2 (12), III R3 (9), IV R4 (8), V R4 (14), and VI R4 (12) rings. In the
c-axis the 2D sheets were further packed into 3D network.
Molecular and supramolecular structure of (2-aminobenzoic acid) :
(p-toluenesulfonic acid) [(HL1)+ · (pts-)] (2)
Fig. 2 should be inserted here.
Compound 2 was also prepared in the same manner as 1, which belongs to
triclinic colorless block crystals in the space group P-1 with Z = 2. The asymmetric

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unit of 2 contains one HL1, and one pts- (Fig. 2s). Similar to 1, compound 2 is also a
salt with the p-toluenesulfonic acid donated the H of the SO3H to the NH2 at L1.
The S-O bonds in the pts- are from 1.4394(18) Å (O(4)-S(1)) to 1.4652(19) Å
(O(5)-S(1)) with the minor ꢀ = 0.0258 Å, indicating the completely deprotonation of
the p-toluenesulfonic acid. This further confirmed our right assignment of 2 as a salt.
The C-O bonds at O1-C1-O2 were 1.210(3) and 1.315(3) Å, respectively. The C-N
bond (1.463(3) Å) at the HL1 was longer than the corresponding C-N bond
(1.3732(16) Å) at the L1 [20], and it also resembled that at 1. Protonation of the N1
was also reflected in the C(4)-C(3)-N(1) and C(2)-C(3)-N(1) angles which were
117.7(2) - 120.6(2)º, being close to that at 1. The torsion angle O(2)-C(1)-C(2)-C(3)
(173.5(2)º) clearly shows the completely coplanarity of the CO2H and the aryl ring.
+
One pts- associated with one HL1 by the N-H···O H-bond from one H of the NH3
-
and one O of the SO3 with N-O distance of 2.778(3) Å, and CH-O association from
-
the 3-CH of the HL1 and the same O of the SO3 with C-O distance of 3.426 Å to
form a heteroadduct. Two heteroadducts were united together by the O-H···O H-bond
-
between the COOH and the second O of the SO3 with O-O distance of 2.641(3) Å to
give a tetracomponent assembly. In the a-axis the tetracomponent assemblies were
+
-
brought into 1D chain by the N-H···O H-bond from the NH3 and the SO3 with N-O
+
distance of 2.859(3) Å, N-H···S hydrogen bond between the NH3 and the S of the
-
SO3 with N-S distance of 3.821(2) Å, CH-O association between the 2-CH of the pts-
-
-
and the SO3 with C-O distance of 3.349 Å, and O-Cπ contact from the SO3 and the
π-C of the COOH with O-C separation of 3.017 Å. The O-C separation resembled the
filed value of 3.019(4) Å [24].
2
1
2
4
The chain displayed the VII R1 (3), VIII R2 (6), IX R3 (9), and X R4 (12) rings.
The 1D chains were further connected together by the Cπ-π association from the π-C
of the COOH and the phenyl nucleus of the HL1 with C-Cg separation of 3.280 Å,
and π-π stacking between the phenyl rings of the HL1 with Cg-Cg separation of 3.381
Å to show 2D sheet running parallel to the ab plane (Fig. 2). In the c-axis the 2D
sheets were further propagated by the CH3-O association from the CH3 of the pts- and
-
the SO3 of two adjacent layers with C-O separation of 3.624 Å to make 3D layer

ACCEPTED MANUSCRIPT
network with the neighbor sheets glided some distance from each other along the
2
extending directions. The intersheet CH3-O associations enclosed the XI R2 (16) ring.
Molecular and supramolecular structure of (4-aminobenzoic acid) :
(p-toluenesulfonic acid) [(HL2)+ · (pts-)] (3)
Fig. 3 should be inserted here.
The compound 3 with the composition [(HL2)+ · (pts-)] was obtained by reacting
equal mol L2 and p-toluenesulfonic acid, which crystallizes as monoclinic colorless
crystals in the space group P2(1)/c with Z = 8. The asymmetric unit of 3 had two HL2,
and two pts- (Fig. 3s), the molecular composition of 3 was similar to 2 and 4-chloro-
anilinium 4-methylbenzenesulfonate [25].
The compound 3 is categorized as a salt where the SO3H of the p-toluenesulfonic
acid is absolutely ionized by H transfer to the NH2 of the L2. The bond lengths and
-
angles at SO3 are not perfectly equivalent, but vary with the environment around the
O, their values listed in Table 2, show relatively little distortion from a regular
-
pyramid. The S-O bonds in the SO3 cover the range of 1.436(6) Å - 1.480(6) Å with
the average value being 1.453(6) Å, which resembled the average S-O bond length in
the known case [26]. The average value of the O-S-O angles (110.9(5)-114.6(5)º) is
112.1(4)º, which fits well with the angle at the reported data [25]. The C-N bonds
(N(1)-C(5), 1.449(10) Å, and N(2)-C(12), 1.452(9) Å) are significantly larger than the
corresponding C-N bond (1.408(3) Å) at the β-polymorph of the 4-aminobenzoic acid
[27], but the C-N bonds were comparable to the corresponding value (1.4620(19) Å)
at the salt generated by 3-carboxy-4-hydroxybenzenesulfonic acid and
4-aminobenzoic acid [12c]. The lengthening of the C-N bond further verified our right
assignment of the cation.
The C-O bonds at the COOH of HL2 were 1.257(15) Å (O(2)-C(1)), 1.272(15) Å
(O(1)-C(1)), 1.206(10) Å (O(4)-C(8)) and 1.354(11) Å (O(3)-C(8)), respectively. The
difference between the pair of C-O bonds in O(4)-C(8)-O(3) was larger than that in
O(2)-C(1)-O(2), suggesting more strong conjugate effect in O(2)-C(1)-O(2) than

ACCEPTED MANUSCRIPT
O(4)-C(8)-O(3). This fact was also reflected in the Caromatic-Ccarboxyl bond where the
C(1)-C(2) (1.508(14) Å) was longer than C(8)-C(9) (1.486(11) Å). The C(8)-C(9) is
slightly shorter than that observed in the deprotonated 4-aminobenzoic acid [28],
strengthening that the deprotonation of the carboxyl group did not occur.
+
A pts- was bonded to a HL2 via the N-H···O H-bond from one H of the NH3 and
-
one O at the SO3 with N-O distance of 2.913(9) Å to form a heteroadduct A. The
other pts- was bonded to the other HL2 via the N-H···O H-bond from one H of the
+
-
NH3 and one O at the SO3 with N-O distance of 2.854(9) Å, and N-H···S H-bond
-
between the same H and the S of the SO3 with N-S distance of 3.403(7) Å to form a
heteroadduct B. The heteroadducts A and B were tied together by the N-H···O
-
H-bond with N-O separation of 2.811(10) Å, O-O contact between the SO3 with O-O
-
separation of 2.980 Å, and O-π association between one O of the SO3 and the aryl
ring of the cation with O-Cg separation of 3.130 Å to form a tetracomponent
aggregate. The O-Cg separation was close to that in 1. In the b-axis the
tetracomponent aggregates were connected together by the N-H···O H-bonds with
N-O separations of 2.778(9)-2.830(9) Å, CH-O association from the 2-CH of the
-
anion and the SO3 with C-O distance of 3.484 Å, and CH-O associations between the
-
2/3-CH of the cation and the SO3 with C-O distances of 3.182-3.507 Å to give 1D
2
2
2
2
chain. The chain displayed XII R1 (3), XIII R2 (4), XIV R2 (5), XV R2 (8), XVI
2
3
4
R3 (9), XVII R3 (8) and XVIII R4 (12) rings. At the bc plane the 1D chains were
+
-
linked together by the N-H···O H-bond from the third H of the NH3 and the SO3
with N-O distance of 2.734(9) Å to form 2D sheet (Fig. 3). Two sheets were glued
together by the dimeric O-H···O H-bond of the COOH···HOOC type with O-O
separation of 2.636(10) Å to give a double sheet. The COOH···HOOC association
2
generated the XIX R2 (8) ring. In the a-axis the double sheets were further packed by
the catemeric O-H···O H-bond between the COOH···HOOC with O-O separation of
2.660(8) Å to give 3D network. It was worth to point that the dimeric O-H···O
hydrogen bonds were from C1-O1-O2, the C8-O3-O4 participated in the catemeric
O-H···O H-bond, and the former was slightly stronger than the latter.

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Molecular and supramolecular structure of (2-aminobenzoic acid)2 : (1,
5-naphthalenedisulfonic acid) [(HL1)22+ · (nds2-)] (4)
Fig. 4 should be inserted here.
Cocrystallization of L1 and naphthalene-1,5-disulfonic acid in 1:1 gave single
crystals suitable for XRD, crystal structure determination (Table 1) revealed that
2-aminobenzoic acid and naphthalene-1,5-disulfonic acid are in 2:1. The crystal
structure of 4 consists of one HL1 and half an nds2- in the asymmetric unit (Fig. 4s), 4
crystallizes in the monoclinic space group C2/c. The L1 is protonated at the NH2 also.
+
The C-N bond length concerning the NH3 in HL2 was 1.457(3) Å for N(1)-C(3),
which is like the corresponding bond lengths at both 1 and 2. The S-O bond lengths in
-
the SO3 ranging from 1.448(2) Å to 1.452(2) Å (ꢀ = 0.004 Å) are close to the
corresponding reported S-O bonds [29], the C-O bonds at the COOH were 1.219(3)
(O(2)-C(1)), and 1.302(3) Å (O(1)-C(1)) Å, respectively.
Two HL1, and one nds2- made a tri-component adduct with the R1 (3) rings, and
2
there found an inversion centre at the middle of the C9-C9A. The HL1 associated
+
-
with the nds2- by an N-H···O H-bond from one H of the NH3 and one O at the SO3
with N-O distance of 2.727(3) Å, and one N-H···S H-bond from the same H and the
-
SO3 with N-S distance of 3.600(2) Å. The geometries of the N-H···S H-bond
resembled those at bis(1H-imidazol-3-ium) naphthalene-1,5-disulfonate [30], and
2,2′-disulfanylidene-5,5′-biimidazolidinylidene-4,4′-dione-dimethylformamide-water
(3/2/4) [31].
The tri-component adducts were mediated into 1D chain by the CH···O
-
association from the 6-CH of the HL1 and the SO3 with C-O distance of 3.195 Å. The
1D chains were combined together and continued into 2D sheet (Fig. 4) extending at
the direction that made an angle of ca. 60° with the bc plane by the N-H···O H-bond
+
from the NH3 and the C=O at COOH with N-O distance of 2.968(3) Å. At the sheet
-
the O-H···O H-bond from the COOH and SO3 with O-O distance of 2.639(3) Å, and
-
O-H···S hydrogen bond between the COOH and the SO3 with O-S distance of
3.641(2) Å were also observed.
In the third direction the neighbor sheets were bridged by the N-H···O H-bond

ACCEPTED MANUSCRIPT
+
-
from the third H of the NH3 and the third O at the SO3 with N-O distance of 2.729(3)
Å, and CH-π association from the 5-CH of the HL1 and the naphthalene ring with
C-Cg separation of 3.631 Å into 3D layer network with the neighbor sheets glided
some distance from each other. The C-Cg separation for the CH-π association
resembled that (3.586 Å) in 4-phenethoxyaniline hemihydrate [32]. The 3D layer
2
2
2
3
network had the XX R1 (3), XXI R2 (4), XXII R2 (12), XXIII R3 (10), and XXIV
4
R4 (12) rings.
Molecular and supramolecular structure of (4-aminobenzoic acid) :
(3-nitrophthalic acid) [(HL2)+ · (Hnpa-)] (5)
Fig. 5 should be inserted here.
Compared to the diacid in 4, the dicarboxylic acid in 5 is partially deprotonated
and transferred to the N of the 4-aminobenzoic acid, causing a hydrogenphthalate
salt with the composition of [(HL2)+ · (Hnpa-)]. Salt 5 crystallizes as monoclinic
block crystals in the space group P2(1)/c, and there existed one HL2, and one Hnpa-
in an asymmetric unit (Fig. 5s).
The ꢀ (0.117 Å) between the C-O bonds within the C8-O3-O4 is much greater
than the ꢀ (0.011 Å) in C9-O5-O6. Also the average distance for C-O (1.256(5) Å) in
C9-O5-O6 is less than the C(8)-O(4) (1.310(6) Å) single bond and greater than the
C(8)-O(3) (1.193(6) Å) double bond in the COOH of the Hnpa-. This supports our
right assignment of the Hnpa- monoanion. The C-N bond (N(1)-C(5), 1.456(5) Å)
+
involving the NH3 was similar with the ones at 3 and 4-carboxyanilinium
3-carboxy-4-hydroxybenzenesulfonate [12c], yet it is significantly larger than the
corresponding C-N bond (1.408(3) Å) in the β-polymorph of the 4-aminobenzoic acid
[27]. The lengthening of the C-N bond further supported our right assignment of the
cation. The Caromatic-Ccarboxyl (C(1)-C(2) = 1.477(6) Å) of HL2 is also slightly shorter
than that observed in the deprotonated 4-aminobenzoic acid [28]. The C-C bonds of
the cationic ring were 1.360(8)-1.407(6) Å, the C(8)-C(10) and C(9)-C(11) bond
lengths increased to 1.507(6) Å and 1.519(6) Å respectively, for the attachment of
carboxyl groups. The C(10)-C(11)-C(9) (120.5(4)º) and C(13)-C(12)-C(11) (122.6(5)º)

ACCEPTED MANUSCRIPT
were smaller than the corresponding reported values [33], due to the adjacent electro
negative carboxylic group, the angle C(11)-C(12)-N(2) was increased to 119.6(4)º
which was also comparable with the known data [33].
The rms deviation of the phenyl plane C10-C15 at Hnpa- is 0.0168 Å, the
carboxylates O3-C8-O4/O5-C9-O6 underwent twist by 30.6/80.7° out of this phenyl
plane. Herein the COO- deviated more significantly from the phenyl plane of the
Hnpa- than COOH, which is different from the reported adduct from phthalate [34].
The planes defined by the two carboxyl moieties subtended at 70.1° with each other.
The N2-O7-O8 rotated by 6.3(2)° from the phenyl plane of the Hnpa-, and made
angles of 36.8(3)°/84.3(2)° with the two carboxylates, respectively. The aryl rings of
the cation and anion intersected at 4.9° with each other.
One HL2 was attached to one Hnpa- via the N-H···O H-bond from one H of the
NH3 and one O from the COO- with N-O distance of 2.878(5) Å, and CH-O
+
associations from the 3-CH of the HL2, the O of the COO- that has a N-H···O H-bond,
and the O at the OH of the COOH with C-O separations of 3.253-3.430 Å to give a
bicomponent adduct. At the Hnpa- there were O-O contacts from the COO-, NO2, and
the OH of the COOH with O-O separations of 2.933-3.027 Å, and the O-O distances
were comparable to that at aquadipicrato(tetraethylene glycol)-gadolinium(III) picrate
methanol hemisolvate [35].
In the b-axis the bicomponent adducts were glued into 1D chain by the CH-O
association from the aryl CH of the Hnpa- and the NO2 with C-O separation of 3.167
Å. Two chains were adhered together by the O-H···O H-bond from the COOH and
+
COO- with O-O distance of 2.590(4) Å, N-H···O H-bond between one H of the NH3
and the OH from the COOH with N-O distance of 2.935(5) Å, and N-H···O H-bond
+
from one H of the NH3 and one O from COO- with N-O distance of 2.885(5) Å to
made a double chain. In the bc plane the double chains were bridged together by the
+
N-H···O H-bond from the third H of the NH3 and one O from the COO- with N-O
2
distance of 2.712(5) Å to show 2D sheet (Fig. 5). The sheet exhibited the XXV R1 (7),
1
3
2
2
XXVI R2 (6), XXVII R2 (6), XXVIII R3 (7), and XXIX R4 (8) rings. At the a-axis the
sheets were further packed by the dimeric O-H···O H-bond from the COOH of the

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HL2 with O-O separation of 2.599(5) Å to give 3D network. Similar to 3 the pair of
2
O-H···O H-bonds also produced the XXX R2 (8) ring, but there was no catemeric
O-H···O H-bonds as in 3.
Molecular and supramolecular structure of (3-aminobenzoic acid) :
(trichloroacetic acid) [(HL3)+ · (tca-)] (6)
Fig. 6 should be inserted here.
Compound 6 was also prepared in the same manner as 1-5, which belongs to
monoclinic colorless block crystals in the space group P2(1)/c with Z = 4. Compound
6 is also a salt with the trichloroacetic acid donated the acidic H to the NH2 of the
3-aminobenzoic acid, there contains one HL3, and one tca- in the asymmetric unit
(Fig. 6s). Each Cl of the tca- was disordered over two sites with equal occupancy. The
C-N bond (C(6)-N(1), 1.460(5) Å) is comparable with the corresponding bond at
bis(3-carboxyanilinium) hexafluorostannate(IV) [36].
The C-O bonds at COO- were from 1.226(6) Å (C(1)-O(2)) to 1.259(6) (C(1)-O(1))
with the ꢀ = 0.033 Å (Table 2), in which the relative large ꢀ between the pair of C-O
bonds can be explained by the different H-bonds the two O had (Table 3). The C-O
bonds at O(3)-C(3)-O(4) were 1.319(5) Å (O(3)-C(3)) and 1.223(5) Å (O(4)-C(3)).
The HL3 are similar in conformation to that in the m-carboxyphenylammonium
hydrogen pyrazine-2,3-dicarboxylate [37], with the carboxylic group out of the plane
of the benzene ring with similar torsion angles O(4)-C(3)-C(4)-C(5) (167.1(4)º) for 6,
and C(2B)-C(1B)-C(11B)-O(10B) (165.9(2)°) in the m-carboxyphenylammonium
hydrogen pyrazine-2,3-dicarboxylate, but different from the equivalent angle in the
planar parent acid (cf. -177.8° in the parent acid) [38].
+
One tca- was attached to one HL3 by the N-H···O H-bond from one H of the NH3
and one O of the COO- with N-O distance of 2.746(5) Å to make a heteroadduct. Two
heteroadducts were joined together by O-H···O H-bond between the COOH of HL3
and the other O of the COO- with O-O separation of 2.613(4) Å, and C-π association
from the carboxyl C of the HL3 and the aryl nucleus of the HL3 with C-Cg separation
of 3.317 Å to give a tetracomponent aggregate with the respective units inversionally

ACCEPTED MANUSCRIPT
related. Along the c-axis the tetracomponent aggregates were bridged into 1D chain
+
by the N-H···O H-bond from the second H of the NH3 and the O of the COO- with
the O-H···O H-bond with N-O distance of 2.799(5) Å, together with N-H···Cl
H-bond from the same H as just mentioned with N-Cl separation of 3.431 Å. Along
the ac plane the 1D chains were further bridged into 2D sheet (Fig. 6) by the Cl-Cl
association with Cl-Cl distance of 3.396(4) Å, the Cl-Cl separation being ca. 0.104 Å
shorter than the van der Waals radius of Cl (1.75 Å) was in the range of a filed Cl-Cl
bond [39]. In the b-axis the sheets were further packed by the N-H···O H-bonds from
+
the third H of the NH3 and the C=O of the COOH with N-O distance of 2.790(5) Å,
and CH-O association from the 3-CH of the HL3 and the C=O with C-O separation of
2
1
3.243 Å to give 3D network. The network had the XXXI R1 (5), XXXII R2 (6),
2
4
5
6
XXXIII R4 (18), XXXIV R4 (22), XXXV R6 (18), and XXXVI R6 (26) rings.
Influence of the anions on the architectures of 1-6
In
this
study,
benzenesulfonic
acid,
p-toluenesulfonic
acid,
1,5-naphthalenedisulfonic acid, 3-nitrophthalic acid and trichloroacetic acid, which
has additional functional groups, were used to prepare the six salts. Our study tells
that anions have a significant effect on the architectures of 1-6. In 1-6, the above acids
are essential in making the supramolecular salts. The different acids not only have an
effect on the protonation of the aminobenzoic acid, but also play an important role in
establishing the final architectures via H-bonds and various non-covalent bonds. The
major classical H-bonds had similar role in expanding 1-6.
+
The salts all have the N-H···O H-bonds from the NH3 and the deprotonated
acids. And there were O-H···O H-bonds of the type COOH···deprotonated acidic
units in 1-2, and 4-6, salts 3 and 5 exhibited the homo O-H···O H-bond from COOH.
-
In 1 the SO3 at bzs- plays a key role in forming the 2D net via CH-O contacts. For 2
the final 3D net is dependent solely on the CH3-O association from the pts-. For 3 the
pts- participated in chain extension by the CH-O associations. In 4 the 1D chain was
-
completed only by the CH-O association from the SO3 . The CH-O association from
the aryl CH of the Hnpa- and the NO2 is the only force in 5 which bundled the

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bicomponent adducts into 1D chain. The Cl at 6 was responsible for linking 1D chain
into 2D sheet via the Cl-Cl bonds. The results indicate that the different species of
functional groups, as well as the number and position of the functional group at the
anions, have crucial influences on both the sub and final structures in 1-6.
Conclusions
Six examples of 2-, 3-, 4-aminobenzoic acid-organic acid salts were prepared and
structurally characterized. The underlying supramolecular chemistry in the organic
salts has been unfolded in this article which contributed to the further study of the
aminobenzoic acid-organic acid supramolecular motifs. In the six salts, the NH2 at the
aminobenzoic acids were protonated. Although the organic acids used were different,
there all found the strong intermolecular N-H···O and O-H···O H-bonds, in 1-4 there
are N-H···S H-bonds. There established the additional O-H···S H-bond in 4.
Besides the robust classical H-bonds, other different types of supramolecular
interactions of CH-O/CH3-O, Cl-Cl, CH-π, O-O, O-C, C-π, O-π, and π-π were also
observed in the crystal structures. The extensive non-covalent bonds accompanied
with the varying geometries and number of the acidic groups at the organic acids, has
led to the creation of 3D network, and 3D layer network, however they all possessed
the 1D sub-chain and 2D sub-sheet. From the analysis of the metrics exhibited by
each kind of associations, it suggests that the intra- and interchain non-covalent
interactions have equal importance in the structure propagation of the synthesized
salts. For the conjunction of the various weak nonbonding interactions these structures
had homo or hetero supramolecular synthons or both.
In summary, we have shown that the aminobenzoic acids are good building
blocks in creating 3D supramolecular salts crystals via combination of the classical
and non-classical H-bonds, and we will further scrutinize more multicomponent
supramolecules from aminobenzoic acid and the other acids to further grasp the
supramolecular chemistry of aminobenzoic acid-acid.
Supplementary Information: Crystallographic data for the structural analysis have

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been registered at the Cambridge Crystallographic data center, CCDC Nos. 1542247
for 1, 1446816 for 2, 1445449 for 3, 1450203 for 4, 1445263 for 5, and 1813654 for 6.
These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif,
or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ (UK) with fax +44(1223)336-033 or Email: deposit@ccdc.cam.ac.uk.
Acknowledgment
This research was financed by Zhejiang Provincial Natural Science Foundation of
China.
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