Cyclic oxaalkyl diamide of o-phthalic acid as a new macrocyclic ligand for complexation of Li+ cation

Article abstract of DOI:10.1016/j.molstruc.2009.04.032

Cyclic diamide of o-phthalic acid (CPhDA) was synthesised in the reaction between phtalic anhydride and 1,2-bis(2-aminoethoxy)ethane in high dilution conditions and its ability to form the 1:1 and 2:1 complexes with Li⁺ cations was detected by

Full text of DOI:10.1016/j.molstruc.2009.04.032

Journal of Molecular Structure 930 (2009) 26–31
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Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Cyclic oxaalkyl diamide of o-phthalic acid as a new macrocyclic ligand
for complexation of Li+ cation
*
´
Adam Huczynski, Małgorzata Ratajczak-Sitarz, Andrzej Katrusiak, Bogumil Brzezinski
Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Cyclic diamide of o-phthalic acid (CPhDA) was synthesised in the reaction between phtalic anhydride and
1,2-bis(2-aminoethoxy)ethane in high dilution conditions and its ability to form the 1:1 and 2:1 com-
plexes with Li+ cations was detected by ESI mass spectrometry. The 1:1 complex was obtained in the solid
state and studied by X-ray diffraction, FT-IR, NMR and PM5 semiempirical methods. The structure of 1:1
complex was also studied in acetonitrile. It was found that the structures of 1:1 complex are different in
the solid and in solution.
Received 19 March 2009
Received in revised form 15 April 2009
Accepted 17 April 2009
Available online 3 May 2009
Keywords:
Ó 2009 Elsevier B.V. All rights reserved.
Cyclic amido-ethers
Lithium cation complex
Ionophores
Crystal structure
Cyclic diamide
1. Introduction
without any further purification. CD3CN and CH3CN spectral-grade
solvents were stored over 3 Å molecular sieves for several days. All
Macrocycles are possibly the widest used family of host com-
pounds in supramolecular chemistry [1]. Among different areas
of supramolecular chemistry, the synthesis of cyclic diamides has
been a subject of intensive studies because of their wide applica-
tions in chemistry, biology, molecular recognition, medicine,
industry and agriculture [1,2]. They are highly capable of selective
and effective complexation of various transition and heavy metal
cations as well as some neutral molecules and anions [3]. Macrocy-
clic diamides are valuable intermediates for the preparation of
aza-crown compounds and more complicated ligands such as
cryptands [4]. Some diamide-containing macrocycles have been
used as new catalysts [5] or molecular receptors for molecular rec-
ognition of biologically interacting substrates including anti-HIV
active drugs [6]. Designing of an efficient ionophore for lithium
cation presents a considerable problem because of its relatively
small ionic diameter with the respect to the other alkali metal cat-
ions [7]. We report here the ionophoric properties of cyclic benzo-
substituted diamide (CPhDA) (Scheme 1) toward lithium cations.
manipulations with the substances were performed in a carefully
dried and CO2-free glove box.
2.1. Synthesis of CPhDA
A
solution of (1.48 g, 1.0 ꢀ 10ꢁ2 mol) 1,2-bis(2-aminoeth-
oxy)ethane, (1.48 g, 1.0 ꢀ 10ꢁ2 mol) phthalic acid anhydride in
the 300 ml of anhydrous toluene was stirred under reflux for
24 h under argon atmosphere. After this time the solvent was
evaporated under reduced pressure and the solid residue was
washed with chloroform (3 ꢀ 10 ml). The chloroform solution
was combined and evaporated under reduced pressure to dryness.
The solid residue was purified by chromatography (CHCl3/CH3OH,
5:1) on silica gel (Fluka, type 60), yield – 420 mg, 15.1%. (See
Scheme 1, method a.).
2.2. Synthesis of CPhDA–LiClO4–H2O (1:1:1) complex
The appropriate lithium perchlorate (1.0 mmol) in warm aceto-
nitrile (5 cm3) was added to a solution of CPhDA (1.0 mmol) in
warm acetonitrile (2 cm3). Crystals suitable for X-ray crystallogra-
phy were grown by slow crystallization from acetone solutions.
2. Experimental
1,2-Bis(2-aminoethoxy)ethane, o-phthalic acid anhydride and
phthaloyl dichloride were purchased from Sigma–Aldrich. The lith-
ium perchlorate was commercial product of Sigma and was used
2.3. X-ray crystal structure analysis
The X-ray diffraction measurements were carried out on a
Kuma KM-4 CCD diffractometer at 293 K. The structure was
* Corresponding author. Tel.: +48 61 8291330.
E-mail address: bbrzez@amu.edu.pl (B. Brzezinski).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.04.032

´
27
A. Huczynski et al. / Journal of Molecular Structure 930 (2009) 26–31
O(1)
O
O
NH
NH
O
O
NH
O
O
6
7
N(1)
N(4)
O
14
1
NH
(b)
(a)
O
O
O
O(4)
CPhDA
(yield 15%)
CPhDA
(yield ~2%)
O
(1)
O
O
O
O
O
N
O
O
N
N
O
N
O
O
(2)
(yield 30%)
(2)
(yield 35%)
O
O
Scheme 1. Synthesis of cyclic diamide of o-phthalic acid (CPhDA). Reagent and conditions: (a) o-phthalic anhydride (1) (1.0 equiv), 1,2-bis(2-aminoethoxy)ethane (1.0 equiv),
toluene, 100 °C, 24 h; (b) o-phthalic anhydride (1) (1.0 equiv), 1,2-bis(2-aminoethoxy)ethane (1.0 equiv), lithium perchlorate (2.0 equiv), acetonitrile, 80 °C, 24 h.
solved by direct method with SHELXS-97 [8] and refined with
SHELXL-97 [9]. All on-hydrogen atoms were anisotropically re-
fined. Two H-atoms at O(W1) were located from the difference
Fourier maps and refined with isotropic temperature factors. All
other H-atoms were calculated from the molecular geometry,
and their Uiso’s were related to the thermal vibrations of their car-
riers. The crystallographic-information-file (CIF) has been depos-
max./min. residual electron density 0.28/ꢁ0.44 e Åꢁ3. The bond
distances and angels are listed in Table 1 and hydrogen-bonds
geometry is described in Table 2.
2.4. ESI mass spectrometry
The electrospray ionization (ESI) mass spectra were recorded on
a Waters/Micromass (Manchester, UK) ZQ mass spectrometer
equipped with a Harvard Apparatus syringe pump. All sample solu-
tions were prepared in acetonitrile (1.0 ꢀ 10ꢁ5 mol dmꢁ3). The
measurements were performed for the solutions of KTA-TBD com-
plex. The samples were infused into the ESI source using a Harvard
ited with Cambridge Crystallographic Database Centre as
a
supplementary Publication No. CCDC 714396. A copy can be ob-
tained free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, fax: +44(12) 23336 033, e-mail:
deposit@ccdc.cam.ac.uk.
Crystals of CPhDA–LiClO4–H2O were obtained by recrystallisa-
tion from acetone: M = 384.69, monoclinic, space group P21/c
(No. 14), a = 10.6095(9) Å, b = 10.6336(9) Å, c = 17.0492(14) Å,
pump at a flow rate of 20 l
l minꢁ1. The ESI source potentials were:
capillary 3 kV, lens 0.5 kV, extractor 4 V. In the case of standard ESI
mass spectra the cone voltage was 70 V. The source temperature
was 120 °C and the dessolvation temperature was 300 °C. Nitrogen
was used as the nebulizing and dessolvation gas at flow-rates of
100 and 300 1 hꢁ1, respectively. Mass spectra were acquired in
the positive ion detection mode with unit mass resolution at a step
of 1 m/z unit.
b = 102.12(1) Å,
V = 1880.6(3) Å3,
Z = 4,
dc = 1.359 g cmꢁ3
,
2hmax = 48.28, F(0 0 0) = 800. A total of 13,592 reflections were
measured, 4729 unique. The final cycle of full-matrix least squares
refinement was based on all observed reflections, 293 variable
parameters, with factors of R = 0.067, wR2 = 0.145, GOF = 0.958,
Table 1
Selected bond lengths (Å) bond angles (°) and torsion angles (°) determined from X-ray measurement of CPhDA–LiClO4–H2O crystal.
Bond lengths (Å)
Bond angles (°)
Torsion angles (°)
O(1)–C(7)
O(2)–C(10)
O(2)–C(9)
O(3)–C(12)
O(3)–C(11)
O(4)–C(14)
N(1)–C(7)
1.2407(18)
1.432(2)
1.436(2)
1.438(2)
1.450(2)
1.2422(19)
1.333(2)
1.467(2)
1.344(2)
1.475(2)
1.402(2)
1.408(2)
1.504(2)
1.395(3)
1.378(3)
1.388(3)
1.403(2)
1.511(2)
1.512(2)
1.500(3)
1.509(3)
1.143(18)
1.26(2)
C(10)–O(2)–C(9)
C(12)–O(3)–C(11)
C(7)–N(1)–C(8)
C(14)–N(2)–C(13)
C(5)–C(6)–C(7)
C(1)–C(6)–C(7)
O(1)–C(7)–N(1)
N(1)–C(7)–C(6)
N(1)–C(8)–C(9)
112.88(13)
113.42(14)
123.12(13)
124.84(14)
115.68(14)
124.91(13)
123.06(15)
116.74(13)
110.75(13)
107.81(13)
107.72(14)
112.42(15)
109.30(15)
114.27(15)
123.59(15)
114.90(14)
119(3)
C(6)–C(1)–C(2)–C(3)
C(14)–C(1)–C(2)–C(3)
C(4)–C(5)–C(6)–C(7)
C(2)–C(1)–C(6)–C(5)
C(14)–C(1)–C(6)–C(7)
Li(1)–O(1)–C(7)–N(1)
Li(1)–O(1)–C(7)–C(6)
C(8)–N(1)–C(7)–O(1)
C(8)–N(1)–C(7)–C(6)
C(5)–C(6)–C(7)–O(1)
C(1)–C(6)–C(7)–O(1)
C(5)–C(6)–C(7)–N(1)
C(1)–C(6)–C(7)–N(1)
C(7)–N(1)–C(8)–C(9)
C(10)–O(2)–C(9)–C(8)
N(1)–C(8)–C(9)–O(2)
C(9)–O(2)–C(10)–C(11)
C(12)–O(3)–C(11)–C(10)
O(2)–C(10)–C(11)–O(3)
C(11)–O(3)–C(12)–C(13)
C(14)–N(2)–C(13)–C(12)
O(3)–C(12)–C(13)–N(2)
C(13)–N(2)–C(14)–O(4)
C(13)–N(2)–C(14)–C(1)
C(2)–C(1)–C(14)–O(4)
C(6)–C(1)–C(14)–O(4)
C(2)–C(1)–C(14)–N(2)
C(6)–C(1)–C(14)–N(2)
C(7)–O(1)–Li(1)–OW1
ꢁ0.4(3)
ꢁ175.58(16)
ꢁ178.39(15)
0.7(2)
ꢁ6.4(2)
ꢁ19.5(4)
156.1(3)
N(1)–C(8)
0.4(2)
N(2)–C(14)
N(2)–C(13)
C(1)–C(2)
C(1)–C(6)
C(1)–C(14)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
ꢁ175.29(14)
ꢁ56.6(2)
125.41(17)
119.22(16)
ꢁ58.7(2)
ꢁ159.31(15)
ꢁ157.28(15)
9.86(18)
170.99(15)
ꢁ80.8(2)
ꢁ58.9(2)
176.10(14)
86.7(2)
O(2)–C(9)–C(8)
O(2)–C(10)–C(11)
O(3)–C(11)–C(10)
O(3)–C(12)–C(13)
N(2)–C(13)–C(12)
O(4)–C(14)–N(2)
N(2)–C(14)–C(1)
O(44)–Cl(1)–O(33)
O(44)–Cl(1)–O(22)
O(33)–Cl(1)–O(22)
O(1CL)–Cl(1)–O(2CL)
O(44)–Cl(1)–O(11)
O(33)–Cl(1)–O(11)
O(22)–Cl(1)–O(11)
O(1CL)–Cl(1)–O(4CL)
O(2CL)–Cl(1)–O(4CL)
O(1CL)–Cl(1)–O(3CL)
O(2CL)–Cl(1)–O(3CL)
O(4CL)–Cl(1)–O(3CL)
HW1–OW1–HW2
86.3(18)
116(2)
C(8)–C(9)
C(10)–C(11)
C(12)–C(13)
Cl(1)–O(44)
Cl(1)–O(33)
Cl(1)–O(1CL)
Cl(1)–O(22)
Cl(1)–O(2CL)
Cl(1)–O(11)
Cl(1)–O(4CL)
Cl(1)–O(3CL)
106.4(12)
118.1(15)
97.6(17)
122.0(12)
104.2(6)
119.6(10)
116.7(16)
106.8(5)
ꢁ83.67(19)
ꢁ2.6(3)
1.389(11)
1.417(15)
1.422(8)
1.47(2)
1.495(10)
1.498(11)
174.11(16)
127.64(17)
ꢁ47.4(2)
ꢁ49.1(2)
135.81(16)
ꢁ68.3(4)
103.8(4)
100(4)

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A. Huczynski et al. / Journal of Molecular Structure 930 (2009) 26–31
28
Table 2
[13] and the high pressure approach are frequently used [12,14].
In this work, we used two methods for synthesis of CPhDA. In
the first method, the reaction was carried out under high dilution
conditions in toluene using o-phthalic acid anhydride and 1,2-
bis(2-aminoethoxy)ethane (Scheme 1) yielding CPhDA (15%) [15].
Furthermore, side products such as diimide (2) (30%) and an insol-
uble polymer have been obtained. It is interesting to note that
using high dilution condition the reaction of o-phthaloyl dichloride
with 1,2-bis(2-aminoethoxy)ethane under reflux in toluene gave
essentially an insoluble polymer. The second method of macrocyc-
lizations used to obtain CPhDA was metal-templated cyclization in
acetonitrile solution between o-phtalic anhydride and 1,2-bis(2-
aminoethoxy)ethane with addition of lithium perchlorate (Scheme
1) [13]. Unfortunately, the main product of this reaction was dii-
mide (2) (35%) and polymers.
Dimensions of the hydrogen bonds (Å and °) in CPhDA–LiClO4–H2O crystal.
D–Hꢂ ꢂ ꢂA
d(D–H)
d(Hꢂ ꢂ ꢂA)
2.12
2.28
2.14(4)
2.23(6)
d(Dꢂ ꢂ ꢂA)
\(DHA)
N(1)–H(1N)ꢂꢂꢂO(3CL)
N(2)–H(2N)ꢂꢂꢂO(4CL)
O(W1)–H(W1)ꢂꢂꢂO(2CL)i
O(W1)–H(W2)ꢂꢂꢂO(2)ii
0.86
0.86
0.82(4)
0.78(6)
2.944(8)
3.008(4)
2.95(1)
2.91(2)
161
143
166(3)
145(5)
Symmetry code: (i): 1 ꢁ x, ꢁ0.5 + y, 0.5 ꢁ z; (ii): ꢁx, ꢁ0.5 + y, 0.5 ꢁ z.
2.5. Spectroscopic measurements
The FT-IR spectra of CPhDA and its 2:1 and 1:1 complexes were
recorded in KBr pellets (1.5/200 mg) as well as in acetonitrile at
300 K on a Bruker IFS 113v spectrometer (DTGS detector, resolu-
tion of 2 cmꢁ1). For the solution measurements, a cell with Si win-
dows and a wedge-shaped layer was used to avoid interferences
(mean layer thickness: 0.176 mm and the concentration of the
samples 0.1 mol dmꢁ3). The Happ–Genzel apodization function
was used.
3.2. Spectroscopic and structural studies
The ESI mass spectra of 1:1 and 2:1 mixtures of CPhDA with
lithium cation (Fig. 1(a) and (b)) shows the m/z = 285 and m/
z = 563 signals, respectively, demonstrating the formation of the
respective complexes.
Inspired by the mass spectrometry results, we have performed
the spectroscopic (1H NMR and 13C NMR, FT-IR) and structuralinves-
tigation (X-ray, and semiempirical calculations) of these new lith-
ium complexes. The crystals of 1:1 complex between CPhDA and
LiClO4 were obtained from acetonitrile solution as inclusion crystals
with one water molecule [CPhDA–LiClO4–H2O (1:1:1)] (Tables 1 and
2). Unfortunately, no suitablecrystalsfor X-ray measurementsof 2:1
complex of CPhDA with LiClO4 were obtained.
The X-ray diffraction analysis revealed a lattice-type complexa-
tion of lithium, considerably different than that obtained by PM5
calculation. The CPhDA–LiClO4 crystallizes as a hydrate, and the
water molecule participates in the Li+ complexation (Tables 2
and 3). The PM5 calculated and solid state conformations of the
14-membered ring are very similar, and therefore it can be as-
sumed that the CPhDA molecule is not very flexible and favours
this conformation. It can explain the complexation of Li+ observed
in the crystal (Figs. 2 and 3). The Li+ cation is tetrahedrally coordi-
nated by carbonyl O(4) and ether O(3) oxygen atoms of one CPhDA
molecule, by carbonyl O(1) of the neighbouring molecule of CPhDA
and by the oxygen O(W1) from the water molecule. These four
oxygen atoms form a nearly ideal tetrahedron with edges (inter-
oxygen distances) of 3.125–3.274 Å (see Table 3). These distances
are commensurate with the sums of van der Waals radii of oxygen
and small size of the Li+ cation. Meanwhile in the calculated com-
plexes the fourfold coordination tetrahedral are considerably dis-
The 1H NMR measurement in CD3CN was carried out at the
operating frequency 300.075 MHz; flip angle, pw = 45°; spectral
width, sw = 4500 Hz; acquisition time, at = 2.0 s; relaxation delay,
d1 = 1.0 s; T = 293.0 K and using TMS as the internal standard. No
window function or zero filing was used. Digital resolution = 0.2 Hz
per point.
The 13C NMR spectrum was recorded at the operating frequency
75.454 MHz; pw = 60°; sw = 19000 Hz; at = 1.8 s; d1 = 1.0 s;
T = 293.0 K and TMS as the internal standard. Line broadening
parameters were 0.5 or 1 Hz. The error of chemical shift value
was 0.01 ppm.
The 1H and 13C NMR signals were assigned independently for
each species using one or two-dimensional (COSY, HETCOR)
spectra.
2.6. PM5 calculations
PM5 semiempirical calculations were performed using the
CAChe WorkSystem Pro 7.5.0.85 Version [10,11].
3. Results and discussion
3.1. Synthesis
The methods for the preparation of macrocyclic amides have
been extensively reviewed [12]. Among these methods, the high
dilution-techniques [12], the route based on the template effect
Fig. 1. The ESI positive ion mode mass spectra of: (a) 1:1 mixture of CPhDA with LiClO4; (b) 2:1 mixture of CPhDA with LiClO4 at cv = 30 V.

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A. Huczynski et al. / Journal of Molecular Structure 930 (2009) 26–31
Table 3
Coordination schemes of the Li cation. Distances (Å) and angles (°) determined form
X-ray studies and calculated by PM5 semiempirical method.
Used method
X-ray
Compounda
Distances (Å) and angles (°)
CPhDA–LiClO4–H2O
(in crystal)
Liꢂ ꢂ ꢂO(1)
1.916(3)
Liꢂ ꢂ ꢂO(W1)
1.940(4)
1.940(3)
2.047(3)
3.125(2)
3.145(2)
3.176(2)
3.177(2)
3.258(2)
3.274(2)
116.2(2)
106.5(1)
115.3(2)
104.1(1)
109.9(1)
103.2(1)
Liꢂ ꢂ ꢂO(400)
Liꢂ ꢂ ꢂO(300)
O(300)ꢂ ꢂ ꢂO(400)
O(W1)ꢂ ꢂ ꢂO(300)
O(1)ꢂ ꢂ ꢂO(300)
O(W1)ꢂ ꢂ ꢂO(400)
O(1)ꢂ ꢂ ꢂO(400)
O(1)ꢂ ꢂ ꢂO(W1)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(W1)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(300)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
O(W1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(300)
O(W1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
O(300)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
Semiempirical
calculations
CPhDA–Li+ (1:1)
Liꢂ ꢂ ꢂO(1)
1.95
2.02
2.07
2.01
108.9
159.2
87.9
89.7
91.7
81.2
1.94
1.95
1.94
1.95
94.0
116.2
116.0
117.3
119.8
94.1
Liꢂ ꢂ ꢂO(2)
Liꢂ ꢂ ꢂO(3)
Liꢂ ꢂ ꢂO(4)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(2)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(3)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(3)
O(2)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(3)
O(2)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(4)
O(3)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(4)
Liꢂ ꢂ ꢂO(1)
CPhDA–Li+ (2:1)
Liꢂ ꢂ ꢂO(4)
Liꢂ ꢂ ꢂO(100)
Liꢂ ꢂ ꢂO(400)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(4)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(100)
O(1)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
O(4)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
O(4)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(100)
O(100)ꢂ ꢂ ꢂLiꢂ ꢂ ꢂO(400)
a
Structures of compound are showed in Fig. 2 and 6.
the other one with the ether oxygen atom. Two bands assigned to the
stretching vibrations of the N–H groups observed at 3301 and
3274 cmꢁ1 reflect their involvement in the intermolecular hydrogen
bonds of different strength. The crystal structure demonstrates that
one N–H proton is hydrogen bonded with the carbonyl group, while
the other one- with the oxygen atom from the oxaalkyl moiety. The
different involvement of the carbonyl groups in different intermo-
lecular hydrogen bonds is reflected in the complex spectral feature
Fig. 2. (a) A perspective view of symmetry-independent part of the unit cell of the
CPhDA–LiClO4–H2O complex; (b) a perspective view of the coordination scheme of
the Li+ cation. The superscripts refer to the symmetry codes in Table 2. Two sites of
the orientationally disordered perchlorate anions have been shown. The hydrogen
bonds have been indicated by thick dashed lines and the coordination bonds by the
thin dashed lines.
of the
m(C@O) vibrations (amide I) as two bands at 1654 and
1629 cmꢁ1 are observed. Additionally, the band at 1654 cmꢁ1 shows
a shoulder at 1662 cmꢁ1. The complex spectral feature of the amide I
bands is also conserved in the spectral feature of the amide II bands
because they are also observed as two bands at 1552 and 1539 cmꢁ1
[15]. In the spectrum of the CPhDA–LiClO4–H2O (1:1:1) crystal
(Fig. 4, solid line) two bands with maxima at ca. 3378 and
3305 cmꢁ1 are observed indicating the involvement of one of the
N–H protons in the weak intermolecular hydrogen bond with per-
chlorate anion, which is consistent with the X-ray data (Table 2).
torted and the ligand oxygen–oxygen distances exceed 3.7 Å
(O(1)ꢂ ꢂ ꢂO(4) 3.733(2) Å, O(1)ꢂ ꢂ ꢂO(3) 5.865(2) Å, O(4)ꢂ ꢂ ꢂO(2)
3.977(2) Å). It demonstrates that the coordination schemes are
much less efficient energetically and in filling the space around
Li+ than that observed in the crystal (Fig. 3).
The complex formation between CPhDA and lithium cation
could be improved using the FT-IR spectroscopy. This improve-
According to these data the band assigned to m(C@O) vibrations ap-
ment was due to the characteristic changes in
m
(C@O) (amide I)
pears at ca. 1649 cmꢁ1 indicating that the carbonyl group interacts
with the Li+ cation (see Table 3).
and (C–N) (amide II) vibration upon complexation.
m
The spectrum of the crystals of CPhDA–LiClO4–H2O (1:1:1) in a
KBr pellet shown in Fig. 4 is compared with that of crystalline
CPhDA–H2O (2:1) [15]. Fig. 4b shows the same spectra on the ex-
tended scales. The structure of CPhDA–H2O is known [15]. In its
FT-IR spectrum the two bands at 3550 and 3475 cmꢁ1 are assigned
to the OH stretching proton vibrations of the water molecules pres-
ent in the crystal. The crystal structure of 2CPhDA–H2O showed that
one N–H proton is hydrogen bonded with the carbonyl group, while
The FT-IR spectra of 1:1 (solid line) and 2:1 CPhDA–LiClO4
(dashed–dotted line) water free complexes and for comparison
also the spectrum of CPhDA (dashed line), all in acetonitrile solu-
tions, are compared in Fig. 5. The differences between these spectra
are connected with the engagement of the carbonyl group in the
coordination process of Li+ cation in the structures of the com-
plexes. In FT-IR spectrum of CPhDA (Fig. 5b, dashed line), the band
at 1664 cmꢁ1 is assigned to the
m(C@O) vibrations (amide I band).

´
30
A. Huczynski et al. / Journal of Molecular Structure 930 (2009) 26–31
Fig. 3. Arrangement of complex CPhDA–LiClO4–H2O (1:1:1) in the crystal lattice, projected along the [0 1 0] crystal direction.
100
50
0
100
(a)
(a)
3305
50
3360
3378
3500
0
4000
4000
3000
2500
2000
1500
1000
500
3500
3000
2500
2000
1500
1000
1552
500
100
100
50
0
(b)
(b)
1552
1550
50
1649
1658
1538
1547
1550
1654
1700
1629
1600
1561
1600
1664
1700
0
1800
1750
1650
1500
1800
1750
1650
1500
Wavenumber [cm-1]
Wavenumber [cm-1
]
Fig. 5. The FT-IR spectra of crystal of 1:1 mixture of CPhDA with LiClO4 (—), 2:1
mixture of CPhDA with LiClO4 (– ꢂ –) and water free CPhDA (- - -) in the CH3CN: (a)
Fig. 4. The FT-IR spectra of crystal of [CPhDA–LiClO4–H2O (1:1:1)] (—) and [CPhDA–
H2O (2:1)] (- - -) recorded in KBr pallet: (a) 4000–400 cmꢁ1; (b) 1800–1500 cmꢁ1
.
4000–400 cmꢁ1; (b) 1800–1500 cmꢁ1
.
The position and shape of the amide I bands in the spectra of 1:1
and 2:1 complexes are changed, i.e. these bands are shifted to-
wards lower wavenumbers and become broadened, demonstrating
that the oxygen atoms of the C@O amide groups are engaged in the
complexation process of the Li+ cation (Table 3). It is also interest-
ing to note that the position of the amide II band in the spectra of
the complexes is also very sensitive to this complexation process.
In the FT-IR spectra of the 1:1 and 2:1 complexes, the amide II band
observed in the spectrum of CPhDA at 1538 cmꢁ1, are shifted to-
tons are the most sensitive to complexation because of the involve-
ment of the oxygen atom of amide groups in coordination of Li+
cation. Comparison of the 13C NMR chemical shifts in the spectra
of the complex with those observed in the spectrum of CPhDA sug-
gests not only that the oxygen atom of the carbonyl group takes
part in the cation coordination but also indicates that the oxygen
atom in the oxaalkyl moiety is also engaged in the complexation
process to a small degree.
On the basis of the spectroscopic results, the structures of 1:1
and 2:1 complexes of CPhDA with Li+ were calculated using the
PM5 semiempirical method [10,11]. The inter-atomic distances be-
tween the coordinated Li+ and the coordinating oxygen atoms
within the respective structures are summarized in Table 3 and
visualized in Fig. 6a and b, respectively. In the structure of the
1:1 complex, two oxygen atoms of the carbonyl groups and two
oxygen atoms of the oxaalkyl moiety are involved in the coordina-
wards higher wavenumbers to about 1552 cmꢁ1 and 1547 cmꢁ1
,
respectively. The shift of the amide II band to higher frequencies
is connected with the increase in the C–N bond order of the amide
group.
The 1H and 13C NMR chemical shifts of CPhDA and its 1:1 com-
plex with LiClO4 are collected in Table 4. Comparison of the 1H
NMR data shows that the signals of the C(2,5)H and N(1,2)H pro-

´
31
A. Huczynski et al. / Journal of Molecular Structure 930 (2009) 26–31
Table 4
1H and 13C NMR chemical shifts (ppm) of proton and carbon atom signals of CPhDA and its (1:1) complex with LiClO4 in CD3CN.
1H NMR
CPhDA
13C NMR
CPhDA
CPhDA:LiClO4 (1:1)
D
CPhDA:LiClO4 (1:1)
D
C(1,6)H
C(2,5)H
C(3,4)
C(7,14)
C(8,13)H2
C(9,12)H2
C(10,11)H2
N(1,2)H
–
–
–
136.11
129.14
130.78
169.31
40.07
69.77
69.58
–
135.72
128.74
131.17
170.86
40.27
69.53
69.22
–
–0.39
–0.40
0.39
1.55
0.20
–0.24
–0.36
–
7.57
7.42
–
3.50
3.60
3.57
7.09
7.53
7.53
–
3.50
3.62
3.59
7.25
–0.04
0.11
–
0.00
0.02
0.02
0.16
D
= dCPhDA:LiClO4 (1:1) ꢁ dCPhDA.
4. Conclusions
Cyclic diamide of o-phthalic acid (CPhDA) was synthesised and
it is demonstrated by ESI mass spectrometry that this compound
forms 1:1 and 2:1 complexes with Li+ cations. The 1:1 complex
was obtained in the solid state and its structure is determined by
X-ray diffraction method. The structure in the solid is compared
with that in the solution using FT-IR, NMR and PM5 semiempirical
methods. It is found that the structures of 1:1 complex in both
states are different.
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tion of the Li+ cation. In contrast to the structure of the 2:1 com-
plex, only the oxygen atoms of the carbonyl groups are engaged
in this process.