Journal of Minerals & Materials Characterization & Engineering, Vol. 9, No.4, pp.321-330, 2010 Printed in the USA. All rights reserved
Structural and Optical Characterization Studie s on
2, 4- dinitrophenylhydrazine Single Crystal
T. Uma Devi *a, N. Lawrenceb, R. Ramesh Babuc, K. Ramamurthic,
G. Bhagavannarayanad
aDepartment of Physics, Government Arts College for Women(Autonomous), Pudukkottaii –
622001, India.
bDepartment of Physics, St. Joseph’s College (Autonomous), Tiruchirappalli –620002, India.
cCrystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University,
Tiruchirappalli –620024, India.
d Materials Characterization Division, National Physical Laboratory, Dr. K. S. Krishnan
Marg, New Delhi-110 012, India
*Corresponding Author:
Single crystal of an organic nonlinear optical (NLO) material, 2,4-Dnitrophenylhydrazine
(DNPH), was grown by slow cooling method. Powder X-ray diffraction (PXRD), Fourier transform
infrared (FT-IR) FT-Raman and NMR studies have confirmed respectively the crystal structure and
functional groups of the grown crystal. Crystalline perfection of single crystals was evaluated by
high resolution X-ray diffractometry (HRXRD) using a multicrystal X–ray diffractometer and found
that the grown crystals are nearly perfect. UV-Visible-NIR spectral analysis was used to determine
the optical constants and band gap of DNPH. Fluorescence spectrum of DNPH was recorded.
Keywords: X-ray diffraction, Growth from solutions, Single crystal growth, Nonlinear optic
The properties of hydrazides and hydrazones are of interest due to their biological activities and
their use as metal extracting agents [1]. The hydrazone derivatives are used as fungicides, and in
the treatment of diseases such as tuberculosis, leprosy and mental disorders. The complexes of
322 T. Uma Devi, N. Lawrence, R. Ramesh Babu, K. Ramamurthi, G. Bhagavannarayana Vol.9, No.4
various hydrazones are reported to act as inhibitors of enzymes [2]. Many substituted hydrazides
are employed in the treatment of psychotic and psychoneurotic conditions. Carboxylic acid
hydrazides are known to exhibit strong antibacterial activities which are enhanced by
complexation with metal ions. The study of biological activity on 2,4-dinitrophenylhydrazine
(DNPH) proved that DNPH is an important material for biological applications. 2,4-
dinitrophenylhydrazine is also an important constituent in various biomedical, pharmaceutical
products and in toxicology [3, 4]. Single crystal 3-dimensional X-ray structure of DNPH was
reported by Okabe et al. [5]. Wardell et al. [6] have analyzed the molecular and supramolecular
structures of DNPH. Chis et al. [7] have reported a combined experimental and theoretical study
on molecular structure of DNPH. Sundaraganesan et al. [8] have investigated the vibrational
spectra of this molecule and identified the various normal modes of vibrations. In this chapter the
growth of DNPH and its characterization is presented.
2.1 Choice of Solvent and Solubilty
The chemical structure of DNPH (C6H6N4O4) is presented in Fig. 1. Solvents offering moderate
solubility-temperature gradient for a material and yielding prismatic growth habit will be
considered as suitable solvents for growing crystal of that material. Another important factor
influencing the habit of growing crystal is the polarity of the solvents and stirring the solution [9-
11]. Acetone (electric dipole moment 2.88 Debye) was found to yield prismatic transparent
crystals and hence it was selected as the suitable solvent to grow DN PH.
Fig. 1. The chemical structure of DNPH.
2.2 Growth of DNPH Crystal
Recrystallized salt of DNPH was dissolved in acetone to prepare the saturated solution at 30 °C.
About 300 ml of this solution was taken in a beaker and placed in a constant temperature bath
(CTB) having an accuracy of ± 0.01 °C. Crystals were grown by the slow cooling method by
reducing the temperature from 30 °C at the rate of 0.1 °C per day. Single crystal of dimension
8x4x2mm3 was grown (Fig. 2) in a period of 7 days.
Vol.9, No.4 Structural and Optical Characterization 323
Fig. 2. As grown DNPH.
3.1 Single Crystal X-Ray Diffraction
Single crystal X-ray diffraction study shows that DNPH crystallizes in a monoclinic system.
There is good agreement between the measured and the corresponding reported values [5] of cell
parameter and are presented in Table 1. Also, the powder XRD pattern recorded are indexed and
shown in Fig. 3.
Fig. 3. X-ray powder diffractogram of DNPH.
Table 1 Comparison of unit cell parameters
S.No. a ( Å) b (Å) c (Å) β (º) References
1. 4.7812 11.5923 14.0521 98.411 Present Work
2. 4.7917 11.5905 14.0496 98.372 [5]
324 T. Uma Devi, N. Lawrence, R. Ramesh Babu, K. Ramamurthi, G. Bhagavannarayana Vol.9, No.4
Before recording the diffraction curve to remove the non-crystallized solute atoms remained on
the surface of the DNPH crystal and also to ensure the surface planarity, the specimen was first
lapped and chemically etched in a non-preferential etchent of water and acetone mixture in 1:2
volume ratio. Fig. 4 shows the high-resolution diffraction curve (DC) recorded for a typical
DNPH single crystal specimen using (220) diffracting planes in symmetrical Bragg geometry by
employing the multicrystal X-ray diffractometer with MoKα1 radiation. The solid line
(convoluted curve) is well fi t t e d w it h the experimental points represented by the fil led recta ngle s.
On deconvolution of the diffraction curve, it is clear that the curve contains two additional peaks,
which are 125 and 157 arc s away from the main peak. These two additional peaks correspond to
two internal structural low angle (tilt angle 1 arc min but less than a degree) boundaries [12]
whose tilt angles (misorientation angle between the two crystalline regions on both sides of the
structural grain boundary) are 125 and 157 arc sec from their adjoining regions. The FWHM (full
width at half maximum) of the main peak and the low angle boundaries are respectively 102, 96
and 170 arc sec. Though the specimen contains low angle boundaries, the relatively low angular
spread of around 10 arc min of the diffraction curve and the low FWHM values show that the
crystalline perfection is reasonably good. The effect of such low angle boundaries may not be
very significant in many applications, but for the phase matching applications, it is better to
know these minute deta i l s regarding crystalline perfection [13].
Fig. 4. High-resolutio n X-ray diffraction curve of DNPH single crystal.
3.3 Fourier Transform Infrared Raman Spectral Analyses
The FTIR spectrum of the grown DNPH recorded in the KBr phase in the frequency region 400
– 4000 cm-1 using Jasco Spectrometer FTIR, model 410 and Raman spectrum recorded for
DNPH are shown in Fig. 5 and Fig. 6 respectively. The vibrational frequencies of various
functional groups along with tentative frequency assignment are presented in Table 2.
Vol.9, No.4 Structural and Optical Characterization 325
Fig. 5. FTIR spectrum of DNPH.
Fig. 6. FT-Raman spectrum of DNPH.
326 T. Uma Devi, N. Lawrence, R. Ramesh Babu, K. Ramamurthi, G. Bhagavannarayana Vol.9, No.4
Table 2 Comparison of vibrational frequencies (cm-1) of DNPH with tentative frequency
(cm-1) Raman
(cm-1) Assignments [14]
Work Ref[8] Present
work Ref[8]
3312 3325 3318 N-H symmetric stretching
3099 3087 3101 3102 C- H stretching
1521 1606
1530 C -C stretching
1420 1426 1431 1426 C- C stretching
- -
1333 1373
1335 N= O symmetric stretching
C- N stretching
1314 1319 1316 1319 N- O symmetric stretching
- -
1223 NH2 twisting
N-H in-plane bending
1126 1130 1135 1135 C- H in-plane bending
1061 1061 1070 1066 C- C- C trigonal bending
922 923 931 923 C- C ring breathing
833 839 840 839 NO2 scissoring
744 744 729 716 NO2 wagging
718 716 - - C- C- C in-plane bending
682 692 662 - C- C- C in-plane bending
516 530
508 453
412 453 C- C- C out-of-plane bending
- - 271 225 C-NO2 out-of-plane bending
- - 110 107 NO2 torsion
Vol.9, No.4 Structural and Optical Characterization 327
3.4. NMR Spectroscopy
The proton NMR spectrum of DNPH was recorded using JEOL GSX 400 model at 23 °C.
Powder form of the DNPH crystal was dissolved in acetone. The chemical shift values of the
protons are plotted on the X-axis and the intensity is plotted on the Y axis (Fig. 7). There are
signals at 7.90 ppm (doublet), 8.35 ppm (doublet) and 8.90 ppm (singlet), indicating the presence
of aromatic hydrogens at the positions 3H, 5H and 6H, respectively. A sharp singlet at 10.80
ppm is due to the presence of NH group proton. Also the NH2 groups produce signal at 2.82
ppm. Appearance of additional peaks in the spectrum indicates that the compound is in the pure
Fig. 7. NMR spectrum of DNPH.
3.5 Optical Transmittance
The optical transmittance spectrum of DNPH was recorded using Shimadzu model 1601 in the
range of 300 – 1000 nm and is shown in Fig. 8. Optically clear single crystal of thickness about 2
mm was used for this study. There is no appreciable absorption of light in the entire visible
range. The transmittance between 500 nm and 1000 nm is approximately 23 %. The short
wavelength cutoff occurs at 400 nm.
328 T. Uma Devi, N. Lawrence, R. Ramesh Babu, K. Ramamurthi, G. Bhagavannarayana Vol.9, No.4
Fig. 8. UV-Vis-NIR spectrum.
3.6 Fluorescence Studies
Fluorescence may be expected generally in molecules that are aromatic or contain multiple
conjugated double bonds with a high degree of resonance stability [15]. Fluorescence finds wide
application in the branches of biochemical, medical, and chemical research fields, for analyzing
organic compounds. It is also used as lighting in fluorescent lamps, LED etc. The emission
spectrum for DNPH was recorded using FP-6500 Spectrofluorometer, in the range 320 – 520 nm
(Fig. 9). It is observed that the compound was excited at 320 nm. The emission spectrum shows
a sharp peak at 335 nm due to π - π* transition, and broad peak at 398 nm is due to n - π*
transition [15, 16].
320 345 370 395 420 445 470 495 520 545
Relative Intensity (A.U)
Fig. 9. Emission spectrum of DNPH.
Vol.9, No.4 Structural and Optical Characterization 329
DNPH single crystals of dimension 8x4x2 mm3 were grown by slow cooling method. The XRD
studies confirm the structural identity of the grown crystals. The HRXRD study indicates that the
grown crystal has very low angle boundary, which is due to the solvent incorporation into the
crystal. FT-IR and FT-Raman spectra revealed the presence of various functional groups. NMR
study confirms the placement of protons in DNPH molecule. The UV-Visible spectrum of DNPH
showed that the crystal is transparent in the range 500 – 1000 nm. Fluorescence spectrum shows
that DNPH fluoresces. A Z-scan technique analysis related to nonlinear optics may yield many
interesting aspects of the title compound.
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