Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine - Its vibrational spectra and theoretical calculations

Article abstract of DOI:10.1016/j.saa.2010.08.050

The N-(4-nitrophenyl)-β-alanine in crystalline form directly by the addition of 4-nitroaniline to the acrylic acid in aqueous solution has been obtained. The title β-alanine derivative crystallizes in the P2 ₁/c space group of monoclinic system with four molecules per unit cell. The X-ray geometry of β-alanine derivative molecule has been compared with those obtained by molecular orbital calculations corresponding to the gas phase. In the crystal the molecules related by an inversion center interact via symmetrically equivalent O-H?O hydrogen bonds with O?O distance of 2.656(2) forming a dimeric structure. The dimers of β-alanine derivative weakly interact via N-H?O hydrogen bonds between the H atom of β-amine groups and one of O atom of nitro groups. The room temperature powder vibrational (infrared and Raman) measurements are in accordance with the X-ray analysis. In aqueous solution of 4-nitroaniline and acrylic acid, the double CC bond of vinyl group of acrylic acid breaks as result of 4-nitroaniline addition.

Full text of DOI:10.1016/j.saa.2010.08.050

Spectrochimica Acta Part A 79 (2011) 758–766
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Crystal and molecular structure of N-(4-nitrophenyl)-␤-alanine—Its vibrational
spectra and theoretical calculations
M.K. Marchewka∗, M. Drozd, J. Janczak
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wrocław, 2, P.O. Box 937, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
The N-(4-nitrophenyl)-␤-alanine in crystalline form directly by the addition of 4-nitroaniline to the acrylic
acid in aqueous solution has been obtained. The title ␤-alanine derivative crystallizes in the P21/c space
group of monoclinic system with four molecules per unit cell. The X-ray geometry of ␤-alanine derivative
molecule has been compared with those obtained by molecular orbital calculations corresponding to
the gas phase. In the crystal the molecules related by an inversion center interact via symmetrically
Received 22 October 2009
Received in revised form 7 June 2010
Accepted 26 August 2010
Keywords:
␤-Alanine derivative
Crystal structure
Gas phase structure
DFT calculations
Hydrogen bond
˚
equivalent O–H· · ·O hydrogen bonds with O· · ·O distance of 2.656(2) A forming a dimeric structure. The
dimers of ␤-alanine derivative weakly interact via N–H· · ·O hydrogen bonds between the H atom of ␤-
amine groups and one of O atom of nitro groups. The room temperature powder vibrational (infrared and
Raman) measurements are in accordance with the X-ray analysis. In aqueous solution of 4-nitroaniline
and acrylic acid, the double C C bond of vinyl group of acrylic acid breaks as result of 4-nitroaniline
addition.
Fourier transform infrared
Fourier transform Raman
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
4-Nitroaniline molecule is known as having high quadratic
hyperpolarizability [1,2]. From this reason it is an attractive molec-
ular unit in the nonlinear crystal engineering [3–5]. However, the
crystalline structure of 4-nitroaniline is known to be centrosym-
metric [6]. Therefore, the crystal of 4-nitroaniline does not show
SHG effect. One can expect that its compounds, or derivatives
with optically active compounds may crystallize in the polar space
groups.
2.1. Preparation
The starting compounds, 4-nitroaniline (Aldrich, 99%) and
acrylic acid (Aldrich, 94%) was used as supplied and prepared in
the ratio of 1:1. The dissolved acid was added to the hot solution of
4-nitroaniline. Next the solution was cooled to room temperature
and it remained clear. The solution slowly evaporated during a few
days till the crystals appeared.
It is known that optically active forms (L or D) of amino acids
[7] or/and their complexes or salts, are usually known to form
non-centrosymmetric crystals [8]. For example, several l-alanine
derivatives are used as materials for nonlinear optics [9–14].
During our search for new crystals exhibiting second har-
monic generation, the title crystals were grown. In contrary to
N-(4-nitrophenyl)-l-prolinol [15,16], the our compound of N-
(4-nitrophenyl)-␤-alanine crystallizes in centrosymmetric space
group therefore second harmonic generation should not be
observed [17]. Nevertheless, the title compound seemed to be inter-
ested according to extensive and different N–H· · ·O, O–H· · ·O and
N–H· · ·N hydrogen bonding system that has been characterized by
X-ray crystallography and vibrational spectroscopy.
2.2. X-ray data collection
A colourless single crystal of the title compound having the
edges of 0.40 mm × 0.34 mm × 0.28 mm was used for data collec-
tion on a four circle KUMA KM-4 diffractometer equipped with a
two-dimensional area CCD detector. The graphite monochroma◦-
˚
tized Mo K␣ (ꢀ = 0.71073 A) and ω-scan technique with ꢁω = 0.75
for one image were used for data collection. The 960 images for
six different runs covering over 90% of the Ewald sphere were
performed. Initially the lattice parameters were refined on 153
reflections obtained from 40 images for 8 runs with different
orientation in the reciprocal space. Finally they were refined by
least-squares methods based on all measured reflections. One
image was monitored as a standard for controlling the stability
of the crystal after every 40 images. Integration of the intensi-
ties, correction for Lorenz and polarization effects were performed
using a KUMA KM-4 CCD software [18]. The face-indexed analyti-
∗
Corresponding author. Tel.: +48 668976921.
E-mail addresses: M.Marchewka@int.pan.wroc.pl, dariusz482@kn.pl
(M.K. Marchewka).
1386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2010.08.050

M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
759
Table 1
Due to the poor detector response, the Raman counterparts of the
infrared bands located above 3200 cm−1 are not observed in the
spectrum.
Crystal data and structure refinement parameters for N-(4-nitrophenyl)-␤-alanine
crystal.
Formula
Formula weight (g/mol)
Crystal system, space group
C9H10N2O4
210.19
Monoclinic, P21/c
8.304 (2)
7.900 (2)
15.263 (3)
98.91 (3)
989.2 (4)
The polycrystalline powders were achieved by grinding in agate
mortar with pestle. Samples, as suspensions in Nujol or Fluorolube,
were put between KBr windows and the powder infrared spectra
were taken in the region of 1320–400 cm−1 for suspension in Nujol
and in the region of 4000–1320 cm−1 for suspension in Fluorol-
ube. This procedure allows obtaining the spectrum free of bands
originating either from Nujol or Fluorolube. Far-infrared spectra
were taken in Nujol between polyethylene plates. For elimination
of the side lobes that result after truncating the interferogram with
a boxcar function the Norton–Beer weak apodization function was
used.
˚
a (A)
˚
b (A)
˚
c (A)
ˇ (◦)
3
˚
V (A )
Z
4
˚
ꢀMo K␣ (A)
0.71073
1.411
1.41
2.488
Dcalc (g/cm3)
Dm (g/cm3), flotation
ꢂ (mm−1
)
Crystal size (mm3)
Crystal colour/habit
2ꢃmax (◦)
0.40 × 0.34 × 0.28
Colourless/parallelepiped
58.96
2.5. Theoretical calculations
h k l ranges
−11, 9; −10, 10; −19, 21
Reflections collected
Independent reflections
Observed reflections (F2 > 2ꢄ(I))
Rint
Refinement on F2
R1
wR2 (all data)
Goodness-of-fit, S
Extinction correction
6846
2415
826
The optimized equilibrium structure has been calculated by
seven different ways [21]. The DFT/B3LYP method was used with
3-21G, 6-31G and 6-311G basis sets. Additional calculations were
performed with RHF level of theory with three different basis sets
(6-311G, 6-31G and TZV). The calculation of equilibrium structure
was performed with using MP2 perturbation theory, also.
In two cases of DFT method the values of calculated energy for
investigated molecule were minimal (see Table 3) and in all DFT
calculations the equilibrium structure was slightly different than
in real crystal. The differences originate from the fact that calcula-
tions were performed for free molecule, only. The same result was
obtained for calculation with MP2 method. For calculation of the
harmonic frequencies, infrared intensities and potential energy dis-
tribution (PED) the data corresponding to minimal energy reached
with HF 6-311G basis set was used. Next, the calculation was con-
tinued with the density functional triply-parameter hybrid model
(B3LYP). The 6-311++G(d,p) basis set was used. Strictly speaking
we used the optimized structural parameters of the HF calculation
as starting data in the DFT calculations. During this calculations
one negative frequency was achieved. A single negative frequency
means a saddle point, which indicates a first order transition state.
As is depicted in Fig. 1b, the nitro group seems to be perpendicular
to the benzene ring in contrary to result of X-ray investigations.
However, it should be remembered here, that all calculations were
performed for free molecule, only. Unfortunately, all reasons why
the orientation of nitro group followed from theoretical calcula-
tions is distinctly different from that observed in the crystal (X-ray
data) remain not clear. On the basis of PED calculation the assign-
ments of bands observed in IR spectra were proposed in Table 6.
Calculated IR spectrum is presented in Fig. 4.
0.0162
0.0395
0.0652
1.014
None
−3
˚
Largest difference peak and hole (e A
)
+0.245, −0.183
cal absorption was calculated using the SHELXTL program [19], the
maximum and minimum transmission factors being 0.6106 and
0.5426. A total of 7086 reflections were integrated (5279 indepen-
dent reflections, Rint = 0.0362) were used for structure solution and
refinement.
2.3. Structure solution and refinement
The structure was solved by direct methods by use of SHELXS97
program [20]. Fourier map that calculated using the E ≥ 1.7 gave
the positions of oxygen, nitrogen and most of the carbon atoms.
The remaining non-hydrogen atoms were located from difference
Fourier syntheses. Initially the structure was refined with isotropic
thermal parameters. The hydrogen atoms were located from the
difference Fourier maps, but in final refinement their positions
were constrained using HFIX 43 with isotropic thermal parame-
ters of 1.2Ueq of the nitrogen atoms joined directly hydrogen atoms
(for H atoms of water molecules Uiso = 1.5Ueq of oxygen). In final
refinement all non-hydrogen atoms were refined with anisotropic
thermal parameters by full-matrix least-squares methods using
the SHELXL97 program [20]. Scattering factors for neutral atoms
and calculations for anomalous dispersion were as in SHELXL97
program [20]. Details of the data collection parameters, crystallo-
graphic data and final agreement factors are collected in Table 1.
The normal coordinate analysis has been carried out accord-
ing to the procedure described and recommended by Fogarasi and
Pulay [32]. The frequencies of stretching and bending vibrations
were not scaled.
Calculations were performed with the PC GAMESS [33] program,
version 7.1 (Tornado), build number 4630 performed under Linux
operating system. This job was executed on PC Cluster consisting
three nodes.
2.4. Spectroscopic measurements
The vibrational measurements were carried out at room tem-
perature. Infrared spectra were taken with
a Bruker IFS-88
spectrometer in the region 4000–80 cm−1 region. Resolution was
set at 2 cm−1, signal/noise ratio was established by 32 scans, weak
apodization. Powder Fourier Transform Raman (FT-Raman) spec-
tra were taken with an FRA-106 attachment to the Bruker IFS-88
spectrometer equipped with Ge detector cooled to liquid nitrogen
temperature. Nd3+:YAG air-cooled diode pumped laser of power
ca. 200 mW was used as an exciting source. The incident laser exci-
tation is 1064 nm. The scattered light was collected at the angle
of 180◦, in the region 3600–80 cm−1, resolution 2 cm−1, 256 scans.
3. Results and discussion
During crystallization from the hot solution of 4-nitroaniline
with the acrylic acid used in the molar proportion of 1:1 the one
hydrogen atom is transferred from amine group to the ␣-carbon
atom of vinyl group of acrylic acid (see for example [34]) and as an
addition result the ␤-alanine derivative crystals are formed accord-
ing to the reaction.

760
M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
Table 2
◦
˚
X-ray and calculated geometric parameters (A, ).
X-ray [◦]
RHF [◦]
˚
˚
Bond
X-ray [A]
RHF [A]
Angle
C1–C6
C2–C1
C3–C2
C4–C3
C4–C5
C6–C5
C1–N1
N1–O1
N1–O2
C4–N2
N2–C7
C7–C8
C8–C9
C9–O3
C9–O4
1.376(3)
1.380(3)
1.372(3)
1.401(3)
1.397(3)
1.375(3)
1.447(3)
1.228(3)
1.226(3)
1.369(3)
1.454(3)
1.518(3)
1.484(3)
1.267(3)
1.241(3)
1.426
1.420
1.359
1.469
1.472
1.358
1.456
1.213
1.207
1.299
1.456
1.559
1.514
1.294
1.241
C2–C1–N1
C2–C1–C6
C6–C1–N1
C3–C2–C1
C4–C3–C2
N2–C4–C5
C3–C4–N2
C5–C4–C3
C6–C5–C4
C1–C6–C5
O2–N1–O1
C1–N1–O2
C1–N1–O1
C4–N2–C7
N2–C7–C8
O4–C9–O3
C8–C9–O4
C8–C9–O3
C7–C8–C9
120.0(2)
120.6(2)
119.3(2)
119.4(2)
121.1(2)
122.2(2)
119.7(2)
118.1(2)
120.4(2)
120.2(2)
121.7(3)
119.1(3)
119.2(2)
124.6(2)
112.6(2)
121.6(3)
120.5(3)
117.9(3)
111.7(2)
117.7
124.3
117.9
118.0
120.2
123.9
116.8
119.2
119.7
118.4
130.2
116.3
113.5
131.0
108.9
123.8
121.0
115.1
111.7
crystal, these torsion angles are equal to −175.3(2)◦, 83.3(2)◦ and
−134.1(2)◦, respectively. The equivalent torsion angles in the gas
phase structure are equal to 179.0◦, 134.9◦ and 151.9◦, respec-
tively. The carboxyl groups COOH and C8 atom lie exactly on the
plane in X-ray and is almost planar in ab initio gas phase structures.
However, the carboxyl group, as is illustrated by the values of the
torsion angle of C7–C8–C9–O3, is different oriented in relation to
the rest of molecule as is shown in Fig. 1b. In the gas phase, the
interaction of the H atom of the ␤-alanine group with the carbonyl
oxygen and formation weak intramolecular N2–H2a· · ·O4 hydro-
gen bond is the driving force for the change of the orientation of
the COOH group. The C1–N1 bond joined the nitro group is equal
˚
to 1.444(2) A. This value is comparable to that found in several
nitrobenzene derivatives in which the distance of Car–NO2 bond
˚
ranging from 1.446(3) to 1.476(3) A [22] as well as to those found
˚
in the gas phase structure (1.447(3) A). The C4–N2 bond length of
˚
1.361(2) A is quite similar to that found in several crystals contain-
ing the Car–Nsp2 bond [22] indicating slightly delocalization of the
␲ electrons over this bond. The C7–C8 and C8–C9 bond distances
correlate well with the distance of Csp3–Csp3 and Csp3–Csp2 bonds,
respectively [22]. The differences between the X-ray and calculated
values of the double C O and single C–OH bond lengths of the car-
Fig. 1. View of the molecular structure of N-(4-nitrophenyl)-␤-alanine in crystal (a)
and gas-phase (b) for a comparison. The displacement ellipsoids are drawn at the
50% probability level. H atoms are shown as spheres with arbitrary radii.
˚
boxyl group [1.241(3) and 1.267(3) A in the crystal and 1.241 and
˚
1.294 A in the gas phase, respectively] arise from the interactions
between the carboxyl groups of two molecules related by an inver-
sion center that form the hydrogen bonded dimeric structure. The
almost planar hydrogen bonded fragment of the dimer is typical
for the RCOOH acids in solids, in which the charge is slightly delo-
calized over the ring, and well explain the X-ray intermediate C–O
distances of the carboxyl group.
The ab initio molecular orbital calculation shows the greater
angles of O–C–O of carboxyl and O–N–O of nitro groups than cor-
responding angles in the crystal and can be explained by the steric
3.1. Description of the structure
The molecular structure of obtained ␤-alanine derivative with
the labeling of the atoms is shown in Fig. 1a. Selected X-ray geomet-
rical parameters together with those corresponding to gas phase
structure are collected in Table 2. As revealed by X-ray structure
analysis the six-membered aromatic ring is planar, but shows dis-
tortions from the ideal hexagonal symmetry. The distortions are
entirely consistent with those found in the similar 1,4-disubstituted
benzene derivatives, especially with the p-substituted nitroben-
zene derivatives [8]. The optimized geometry of the aromatic ring
gives values similar to those found in the crystal. Thus, the ring
distortion results mainly from the 1,4-substitution effect and, to a
smaller degree from the crystal packing forces. In the crystal the
planar NO2 group is slightly rotated along the C1–N1 bond. The
inter-planar angle between the planes of nitro group and the phenyl
ring equals to 5.2(1)◦.
Table 3
Comparison of values of equilibrium geometries calculated by different
methods.
Method
Energy of equilibrium geometry
DFT 321
DFT 631
DFT 6311
HF 6311
HF 631
TZV
−754.4066451
−758.1886920
−758.3759346
−754.3564597
−754.1934543
−754.0294778
−755.672314
The conformation of the ␤-alanine fragment (N2C7C8C9OOH)
with respect to the phenyl ring is well described by the torsion
angles of C3–C4–N2–C7, C4–N2–C7–C8 and C7–C8–C9–O3. In the
MP2

M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
761
Fig. 2. Packing of the molecules in N-(4-nitrophenyl)-␤-alanine crystal.
Table 4
Geometry of the hydrogen bonds.
D–H· · ·A
D–H (A)
H· · ·A (A) D· · ·A (A)
Angle D–H· · ·A (◦)
˚
˚
˚
O(3)–H(31)· · ·O(4)a
0.820(15)
0.86
1.85(2)
2.29
2.652(2)
3.113(2)
164(2)
160
N(2)–H(2A)· · ·O(2)b
Symmetry codes: (a) x − 1, y, z, (b) x − 1, y, z.
Table 5
Analysis of the fundamental modes for N-(4-nitrophenyl)-␤-alanine crystal.
C2h
Acoustic
Translational
Librational
Internal
Selection rules
Fig. 3. Room temperature powder FTIR and FT Raman spectra of title crystal.
Ag
Bg
Au
Bu
0
0
1
2
3
3
2
1
3
3
3
3
69
69
69
69
xx, yy, zz, xz
xy, zy
(Y)
(X, Z)
effect of a lone-pair of electrons on the oxygen atoms predicted by
the valence-shell electron pair repulsion theory (VSEPR) [23].
In the crystal the two molecules of N-(4-nitrophenyl)-␤-
alanine related by inversion center form hydrogen bonded
dimeric structure via the pair of symmetrically equivalent
O3–H31· · ·O4i relatively strong hydrogen bonds (see Fig. 2) with
˚
the donor–acceptor (O· · ·O) distance of 2.652(2) A. Additionally, the
dimers are weakly interconnected by the N2–H2A· · ·O2ii hydrogen
bond (cf. Table 4) forming chains that are aligned along the z-axis.
3.2. Assignments of the bands
Fig. 4. Calculated IR spectrum of N-(4-nitrophenyl)-␤-alanine.
For monoclinic system and P21/c space group with Z = 4, each
N-(4-nitrophenyl)-␤-alanine molecule occupy C1 symmetry site.
Total number (297) of optical modes may be divided into 21 lattice
(9 translational and 12 librational) and 276 internal modes. Each
normal vibration of a molecule is splitted into four unit cell modes
(Ag + Bg + Au + Bu) as shown in Table 5.
part observed at 3348 cm−1. The presence of only one band in
this region corroborates the fact, that C C bond was broken
with following C–N bond formation (see Scheme 1). As a con-
sequence, instead of –NH2 group, which gives commonly two
bands (␯aNH2 and ␯sNH2), the one N–H bond is present in
the studied system. The above mentioned very strong infrared
band at 3346 cm−1 correspond to the stretching vibration of N–H
bond. Additionally, the absence of very strong infrared bands
at 1636 and 1616 cm−1 with very strong Raman counterpart at
1639 cm−1 (the strongest band in the whole spectrum presented
in Fig. 3) derived from the stretching vibrations of C C bond
The bands observed in the measured region 4000–80 cm−1
arise from the vibrations of protons in the intermolecular hydro-
gen bonds, the internal vibrations of the 4-nitroaniline moieties,
acrylic acid (␤-alanine) moieties and from the vibrations of the
lattice.
The most pronounced feature of infrared spectrum is the very
strong band at 3346 cm−1 with its very weak Raman counter-
Scheme 1.

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M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
Table 6
The theoretical and experimental frequencies, intensities, PED, and tentative assignment for N-(4-nitrophenyl)-␤-alanine.
FTIR
FT Raman
Calc. freq.
Calc. int. [km/mol]
PED %
Assignment
3715
3344
354
22
O3–H31 100
O3–H31 100
O–H stretch
O–H stretch
3487w
3346vs
3183m
3131m
3109m
˚
3348vw
N–H stretch, N–H· · ·O 3.113 A
3313
3293
36
56
C6–H6 96
C2–H2 57, C3–H3
42
C–H stretch
C–H stretch
3094vw
3086vw
3281
19
C3–H3 57, C2–H2
42
C–H stretch
3084m
3070m
3256
3237
3
12
C7–H71 96
C8–H81 88,
C8–H82 11
C8–H82 88,
C8–H81 12
C–H stretch
C–H stretch
3034m
3155
5
C–H stretch
3021m
2976m
2962m
2969vw
2925vw
3058
37
C7–H72 98,
C7–H71 2
C–H asym stretch
˚
2960mb
␯O–H (A component) d(O· · ·O) = 2.652 A
C–H sym stretch
2907m
2875m
2773m
2752m
2725m
2663m
2650mb
2604m
C–H stretch
˚
␯O–H (B component) d(O· · ·O) = 2.652 A
2591vw
2430vw
2577m
2524m
2501m
2428m
2415m
2390m
2323m
2220w
2001vw
Overtone
Overtone
Overtone
2066
301
C4–N2–H2a 71,
N2–H2a 24
N–H stretch
1965vw
Overtone
Overtone
1919vw
1749vw
1705vs
1802
1774
324
88
C9–O4 44, C4–N2
14
C6–C5 21, C9–O4
15, C4–N2 13
C
O stretch out-of-phase
Aromatic ring C C stretch
C O stretch in-phase
1694ssh
1636w
1672vw
1609vw
1713
1627
460
33
C4–N2 43, C3–C2
14
C9–O3 21, C8–C9
11, N2–C7–H71 11,
C8–C9–O4 10
C–N stretch
C–O stretch out-of-plane
1600vs
1656
1615
46
C6–C5 30, C3–C2
27, C2–C3–H3 14,
C4–C3 12
Aromatic ring C C stretch
C–H stretch
1592vssh
1595w
1590w
131
C4–N2–C7–H71 21,
C4–N2–C7–H72 21,
N2–C7–H72 18,
N2–C7–H71 12
N2–C7–C8–H82 33,
N2–C7–C8–H81 27,
C7–C8–H81 20,
C7–C8–H82 13
1585
35
C–H stretch
1541s
1502s
1541vw
1505w
C–N stretch
NO2 asym stretch
1632
1574
1537
624
16
N1–O2 62, N1–O1
37
1463vs
1468vw
1453vw
Ring stretch
Ring stretch
C–H in-plane bend (ring)
1446ssh
C1–C2–H2 19,
C6–C5–H5 17,
C2–C3–H3 14,
C1–C6–H6 10
C1–C6–H6 32,
C1–C2–H2 21
51
C–H in-plane bend (ring)
1395w
1396vw

M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
763
Table 6 (Continued)
FTIR
FT Raman
1376vw
Calc. freq.
1532
Calc. int. [km/mol]
138
PED %
Assignment
1377m
1365m
C–H in-plane bend (ring)
NO2 stretch
N1–O1 35, C1–N1
15, N1–O2 15
1356vw
1351vw
1351s
NO2 sym stretch
1334vs
1512
1503
199
66
N2–C7–H71 27,
C4–N2–C7–H71 17,
C4–N2–C7–H72 16,
N2–C7–H72 10
C3–C4–N2–H2a 21,
C1–C6 15, C4–C3
12
C–H in-plane bend
Ring stretch
1426vw
1482
1466
181
17
C3–C4–N2–H2a 39,
N2–C7–H72 10
C7–C8–H82 29,
C9–O3–H31 20,
C7–C8–H81 11
N2–C7–H71 18,
N2–C7–H72 15,
C7–C8–H81 12
C2–C1 17,
C–H in-plane bend
C–H in-plane bend
1409w
1395
1373
20
C–H in-plane bend
262
C–C stretch and C–H bend
C9–O3–H31 15,
C2–C3–H3 10
C9–O3–H31 30,
C9–O3 16
C7–C8–H81 25,
C7–C8–H82 20,
N2–C7–H72 16,
N2–C7–C8–H81 11
C6–C5–H5 23,
C2–C3–H3 20,
C3–C2 16,
1355
1329
175
29
C–H out-of-plane bend C–O bend
C–H out-of-plane bend
1320vs
1305vs
1319m
1300vs
1321
16
C–H out-of-plane bend
C1–C6–H6 12,
C1–C2–H2 12,
C6–C5 12
˚
1286vs
1274vs
1236s
1282m
1269m
1236w
O–H bend out-of-phase, O–H· · ·O 2.652 A
˚
O–H bend in-phase, O–H· · ·O 2.652 A
NO2 stretch and C–C stretch
C–H out-of-plane bend
1251
1226
1179
7
C2–C3–H3 13,
C1–C2–H2 12,
C1–C6–H6 12,
C3–C2 11,
C6–C5–H5 11,
C6–C5 11
C1–N1 24,
C1–C6–C5 15,
N1–O1 13, N1–O2
13, C1–C6 12,
C3–C2–C1 10,
C2–C1 10
C4–N2–C7–H71 14,
N2–C7–C8–C9 14,
C4–N2–C7–H72 12,
N2–C7 11
123
12
Out-of-plane ring def
C–H out-of-plane bend
1189s
1184s
1183w
1106m
1145
1140
1
1
C1–C2–C3–H3 35,
C6–C1–C2–H2 26,
C1–C6–C5–H5 11
C2–C1–C6–H6 37,
C1–C6–C5–H5 25,
C2–C1–C6–C5 13,
C6–C1–C2–H2 12
C–H out-of-plane bend
Out-of-plane ring def
1134m
1112vs
C–H in-plane bend
C–N stretch
1121
23
N2–C7 29,
N2–C7–C8 12,
N2–C7–C8–H81 11
1093s
1039w
C–N stretch and C–H bend
Out-of-plane ring def
1039vw
999vw
1061
1041
86
5
C1–C6–C5 32,
C4–C3–C2 21,
C3–C2–C1 14
C7–C8 29,
999m
6(A1) mode of benzene ring
C3–C2–C1 18,
C1–C6–C5 17,
C8–C9 13

764
M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
Table 6 (Continued)
FTIR
FT Raman
982vw
Calc. freq.
1004
Calc. int. [km/mol]
93
PED %
Assignment
979w
C3–C2–C1–C6 46,
C1–C2–C3–H3 17,
C6–C1–C2–H2 17,
C1–C6–C5–H5 15,
C2–C1–C6–H6 11
In-plane ring def
964vw
C–H out-of-plane bend
˚
949m
915
930
106
20
C8–C9–O3–H31 46
C7–C8–C9 21,
O–H out-of-plane def, O–H· · ·O 2.652 A
C–C stretch
C8–C9 13,
C8–C9–O3 11
904w
904vw
857m
971
910
19
44
C7–C8 21, N2–C7
14, C2–C1–C6 11
C1–C6–C5–H5 14,
C6–C1–C2–H2 13,
C1–N1–O2 12,
C–C stretch
856wsh
NO2 in-plane def
C1–C2–C3–H3 12,
C2–C1–C6–H6 10
C8–C9–O3–H31 16,
C1–C6–C5–H5 11
C4–C3–C2–C1 59,
C2–C1–C6–C5 44
C2–C1–N1–O2 25,
C4–C3–C2–C1 10
C2–C1–N1–O1 26,
C2–C1–N1–O2 16
C2–C1–C6 68,
850w
906
845
867
857
776
127
15
97
62
3
C–H out-of-plane bend, out-of-plane ring bend
837s
835vw
803vw
788vw
755vw
NO2 rock and CCO bend
NO2 rock and CH rock
CO2 wag
806vw
C8–C9–O4 20
753s
721w
C–H out-of-plane bend, 4(B1) type
C–C def
716
185
C7–C8–C9 15,
C4–C3–C2 14,
C3–C2–C1 10
699m
637w
695vw
628vw
Out-of-plane ring def 8(B1) mode
C O out-of-plane def
651
635
50
10
C8–C9–O4 37,
C8–C9 21
Out-of-plane ring def, 8(B1) mode
Out-of-plane ring def
618w
601w
C3–C2–C1–C6 33,
C2–C3–C4–N2 15,
C4–N2–C7–C8 12,
C2–C1–C6–H6 10
C3–C2–C1 71,
C1–C6–C5 16,
C2–C1 12
614
22
Out-of-plane ring bend
579vw
539vw
563
548
7
C7–C8–C9 22,
N2–C7–C8 10
C8–C9–O3 29,
C4–N2–C7 11
C–N bend, C–C def
C–O def
542m
48
523wb
517vw
497vw
485vw
418vw
CO2 wag
489m
416w
Out-of-plane ring bend
C–C def
459
421
7
C7–C8–C9 23,
C4–C3–C2–C1 18,
C2–C3–C4–N2 11,
C3–C4–N2–C7 10
C7–C8–C9 34,
C8–C9–O3 23,
C3–C4–N2 14
C3–C2–C1–C6 29,
C2–C1–C6–C5 23
C2–C1–C6–C5 44,
C1–N1–O1 18,
C2–C1–C6 15
411wsh
349w
15
C–C def, C–N def
394vw
408
380
2
5
Out-of-plane ring bend
Out-of-plane ring bend
341vw
331vw
331w
295vw
329
291
245
6
C3–C2–C1–C6 31,
N2–C7–C8–C9 18,
C1–N1–O2 18,
C1–N1–O1 17
C2–C1–N1 19,
C1–N1–O2 17,
C4–C3–C2 13,
C3–C2–C1–C6 11
C2–C1–N1 35,
N2–C7–C8–C9 34
Out-of-plane ring bend
C–O def C–N def
CCN def.
289vwsh
289vw
281vw
18
4

M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
765
Table 6 (Continued)
FTIR
FT Raman
240vw
Calc. freq.
229
Calc. int. [km/mol]
9
PED %
Assignment
237vw
192w
O· · ·O stretch, N· · ·O stretch
C3–C2–C1–N1 34,
C3–C2–C1 14,
CCN def
N2–C7–C8 13,
C1–N1–O1 12,
C4–C3–C2 11
186vw
155vw
195
177
0
4
C7–C8–C9–O3 43,
C7–C8–C9–O4 30,
C3–C2–C1–N1 16
C3–C4–N2–C7 37,
C2–C1–N1–O1 26,
C2–C1–N1–O2 22,
N2–C7–C8–C9 11,
C4–C3–C2–C1 11
C2–C1–N1–O2 28,
C2–C1–N1–O1 19,
C3–C2–C1–N1 19,
C4–N2–C7–C8 19
C4–N2–C7 18,
C3–C2–C1–C6 17,
C3–C4–N2 17,
N2–C7–C8–C9 12,
C3–C2–C1–N1 11,
N2–C7–C8 10
C3–C4–N2–C7 38,
C4–C3–C2–C1 15,
C4–N2–C7 12,
COOH def
CCN def
147w
160
122
3
3
CNO def
CNC def
121vw
98vw
105
3
CNC def
C3–C4–N2 11
82
4
C2–C3–C4–N2 41,
C4–N2–C7–C8 41,
C3–C2–C1–N1 11
CNC def out of plane
−1179
7205
Abbreviations: s—strong, w—weak, v—very, sh—shoulder, b—broad, m—medium, stretch—stretching, bend—bending, wag—wagging, rock—rocking, symm—symmetrical,
breath—breathing, def—deformation.
corroborates the breaking of this bond in the case of studied crys-
tal.
3.5. The hydrogen bonds vibrations
The determination of the arrangement of hydrogen bonds from
X-ray data is useful for the interpretation of vibrational spectra.
According to crystallographic data there are two kinds of hydro-
gen bonds (Table 4). The position of infrared band originating
from the absorption of particular hydrogen bond depends mainly
on their length [30]. According to such a correlation for hydro-
3.3. The vibrations of 4-nitrophenyl moiety
The assignment for internal vibrations of 4-nitrophenyl moi-
ety was done with the help of paper published by Evans [24]
and Gao et al. [25]. Most bands observed in infrared and Raman
spectra belongs to benzene ring modes. Only some of them may
be assigned to the vibrations of N–H bond. For assignment of
phenyl ring modes the classical work of Herzberg [26] as well as
paper by Miller [27] are helpful. Herzberg’s notation was used for
numbering normal modes associated with the phenyl ring. The
bands corresponding to 6(A1) mode of benzene ring were found
at 999 cm−1 in the infrared and Raman spectrum, respectively.
The strong infrared band located at 753 cm−1 with very weak
Raman counterpart at 755 cm−1 was attributed to out-of-plane C–H
deformation, 4(B1), type of vibration of benzene ring. The out-of-
plane ring deformations, 8(B1), give the infrared bands at 721, 699
and 628 cm−1. The good group vibrations of benzene ring are the
stretching one [28]. The very strong infrared bands at 1463 and
1453 cm−1 were assigned to ring stretching type of vibrations. For
other assignment of internal vibrations of 4-nitrophenyl residue
see Table 6.
˚
gen bond of O–H· · ·O type with the length of 2.652 A, one can
expect the deformation vibrations in the ranges of 1300–1100 cm−1
and 1000–800 cm−1, for in-plane and out-of-plane types, respec-
tively. Therefore, two infrared bands at 1286 and 1274 cm−1
with Raman counterparts at 1282 and 1269 cm−1 were attributed
to coupled in-plane vibrations of O–H bonds, out-of-phase and
in-phase, respectively. The medium infrared band located at
949 cm−1 was assigned to the O–H out-of-plane type of vibra-
tion.
The broad absorption in the region of 3300–1800 cm−1 can
be divided into two components with maxima at ca. 2960 and
2650 cm−1, for A and B component, respectively. These bands
originate from the O–H stretching vibrations. The origin of such
absorption was discussed by El-Amine Benmalti et al. [31].
4. Conclusions
3.4. Internal vibrations of ˇ-alanine moiety
The reaction of 4-nitroaniline with acrylic acid yielded N-
(4-nitrophenyl)-␤-alanine in the crystalline form, as a result of
addition of 4-nitroaniline molecule by its amine group to the dou-
ble band of acrylic acid. Most bands of internal vibrations and
vibrations of hydrogen bonds have been identified. The vibrational
Two very weak bands observed in Raman spectrum at 2969 and
2925 cm−1 corresponds to the presence of coupled C–H bonds. They
were assigned to the stretching vibrations of asymmetric and sym-
metric type, respectively. Similar bands were observed at 2958 and
2912 cm−1 in the infrared and Raman spectrum of 2,4,6-triamino-
1,3,5-triazin-1,3-ium tartrate monohydrate [29].
characteristics corroborates structural data which show that C
C
bond of vinyl part of acrylic acid was broken with following for-
mation of C–C bond. Strands as open dimers are present in the

766
M.K. Marchewka et al. / Spectrochimica Acta Part A 79 (2011) 758–766
structure, joined by medium O–H· · ·O type of hydrogen bond inter-
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[17] V.G. Dmitriev, G.G. Gurzadyan, D.N. Nikogosyan, Handbook of Nonlinear Optical
Crystals, 2nd edition, Springer, 1997.
[18] KUMA Diffraction, Wrocław, KM-4 CCD program package Ver. 173.30,
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[19] G.M. Sheldrick, SHELXTL – Program System, Siemens Analytical X-ray Instru-
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[20] G.M. Sheldrick, SHELXL-97, Program for the Solution and Refinement of Crystal
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Additional material comprising full details of the X-ray data
collection and final refinement parameters including anisotropic
thermal parameters and full list of the bond lengths and angles have
been deposited with the Cambridge Crystallographic Data Center
in the CIF format as supplementary publication No. CCDC 665406.
Copies of the data can be obtained free of charge on the application
to CCDC, 12 Union Road, Cambridge, CB21EZ, UK (Fax: +44 1223
336 033; email: deposit@ccdc.cam.ac.uk).
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