Optical and structural properties of chalcone NLO single crystals

Article abstract of DOI:10.1016/j.molstruc.2011.07.038

Organic compound (E)-1-(4-methoxyphenyl)-3-(2,3,5-trichlorophenyl)prop-2- en-1-one [MPTCPP] with molecular formula C₁₆H₁₁Cl ₃O₂ was synthesized using Claisen-Schmidt condensation reaction method. ¹H N

Full text of DOI:10.1016/j.molstruc.2011.07.038

Journal of Molecular Structure 1005 (2011) 1–7
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Optical and structural properties of chalcone NLO single crystals
a
c
d
P.C. Rajesh Kumar a,b, V. Ravindrachary a, , K. Janardhana , H.R. Manjunath , Prakash Karegouda ,
⇑
Vincent Crasta b, M.A. Sridhar c
a Department of Physics, Mangalore University, Mangalagangotri 574 199, India
b Department of Physics, St. Joseph Engineering College, Vamanjoor, Mangalore 575 028, India
c Department of Studies in Physics, University of Mysore, Mysore 570 006, India
d Sequent Scientific Ltd., Mangalore, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 June 2011
Received in revised form 20 July 2011
Accepted 21 July 2011
Available online 9 August 2011
Organic compound (E)-1-(4-methoxyphenyl)-3-(2,3,5-trichlorophenyl)prop-2-en-1-one [MPTCPP] with
molecular formula C16H11Cl3O2 was synthesized using Claisen–Schmidt condensation reaction method.
1H NMR spectra was recorded to identify the various functional groups present in the compound and con-
firm the chemical structure. The single crystals were grown using slow evaporation solution growth tech-
nique. The UV–Visible spectrum study reveals that the crystal is transparent in the entire visible region
and the absorption is observed at 364 nm. The Kurtz powder second harmonic generation (SHG) test
shows that the MPTCPP is NLO active and its SHG efficiency is three times that of urea. Single crystal
XRD study shows that the compound crystallizes in the monoclinic system with a space group Cc. The
corresponding lattice parameters of the crystal are a = 28.215(5) Å, b = 3.9740(4) Å, c = 16.178(3) Å and
V = 1503.0(4) Å3. The micro hardness test was carried out and the work hardening coefficient value (n)
of the crystal was found to be 1.48. This indicates that the crystal is hard and is suitable for device appli-
cation. The thermal study reveals that the thermal stability of the crystal is good.
Keywords:
Chalcone
Single crystal
Non-linear optically active
Crystal growth
UV–Visible
Thermal study
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
threshold, conversion efficiency, phase matching and temperature
stability along with large molecular first hyperpolarizability. Hence
Engineering of new nonlinear materials, both organic and inor-
ganic, structures and devices with enhanced figures of merit has
comported over the past two decades as a major force to drive
nonlinear optics from the laboratory to real applications. The
nonlinear optical (NLO) properties of molecules and their hyperpo-
larizabilities have become an important area of extensive research,
and a lot of experimental and theoretical efforts are focused on
bulk NLO properties (like second order and third orders harmonics)
a continuous effort is going on in the scientific community to opti-
mize these properties of the crystals for industrial applications.
Generally the level of SHG response of a given material is inher-
ently depends upon its structural attributes. The basic structure of
organic NLO materials is based on the
p-bond system. Due to the
overlap of orbital, delocalization of electronic charge distribution
p
leads to a high mobility of the electron density. On a molecular
scale, the extent of charge transfer across the NLO chromophores
determines the level of SHG output. Hence the functionalization
as well as their dependence on the hyperpolarizabilities (b and
of molecules. Currently much attention has been given to organic
NLO materials because of their large first (b) and second ( ) hyper-
c)
of both ends of the p-bond system with appropriate electron donor
c
and acceptor groups can enhance the asymmetric electronic distri-
bution in either or both ground and excited states, leading to an in-
creased optical nonlinearity [6]. Therefore the main work in
organic NLO materials is centered on manipulating these factors
along with a crystal engineering of molecule to get a non-centro-
symmetric network. Among the organic NLO materials (crystals),
chalcone derivatives have an edge over other organic crystals due
to their higher power conversion efficiency, chemical inertness,
high damage threshold and phase matching properties. These
derivatives are also known for their excellent blue light transmit-
tance, large nonlinear optical coefficients, and relatively short cut-
off wavelengths of transmission [7–9] which occurs mainly due to
the presence of conjugated double bonds. Because of the
polarizabilities and high laser damage resistance compared to
inorganic materials. Particularly, a versatile synthetic chemistry
can be used to synthesize, alter and optimize the required molec-
ular compounds with a desired structure to maximize their utility
in industrial applications; hence organic materials are being recog-
nized as the ‘‘materials for future’’ [1–5]. It is known that during
the material selection for industrial applications like in photonics,
the key factors not only depend on laser conditions but also on the
physical properties of the crystal such as transparency, damage
⇑
Corresponding author. Tel.: +91 824 2287363; fax: +91 824 2287367.
E-mail address: vravi2000@yahoo.com (V. Ravindrachary).
0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2011.07.038

2
P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
conjugation the electrons remain delocalized with in the molecule
and influences marginally on the electron polarization. In these
systems the NLO properties like molecular hyperpolarizability
can be further enhanced by substituting different functional
groups on either sides of the chalcone which creates highly polar-
izable conjugated bridge. Moreover the presence of strong inter-
molecular interactions, such as hydrogen bonds, can extend this
level of charge transfer into the supramolecular realm, owing to
their electrostatic and directed nature, thereby enhancing the
SHG response [10]. Considering these theoretical aspects, the syn-
thesis of new organic materials with enhanced NLO property (both
second and third order nonlinearity) is a continuing field of re-
search. In this direction some of the compounds like, LVAP [11],
LVB [12], HBST [13],VHBr [14], LADLMA [15], LHTF [16], DMAP
[6], KAP [17], CAFP [18], N-(2-hydroxybenzylidene)acetohydrazide
[19] etc., are reported for NLO properties. In this view, we are
reporting the synthesis, growth and characterization of new
chalcone derivative, (E)-1-(4-methoxyphenyl)-3-(2,3,5-trichlor-
ophenyl)prop-2-en-1-one [MPTCPP] along with mechanical and
thermal properties.
temperature controller unit. Knowing the weights of the solute and
the solution, the solubility was measured using the formula [21],
Solubility ðWt%Þ ¼ Weight of the solute
ꢀ 100=Weight of the ðsolute þ SolventÞ: ð1Þ
This process was repeated for 3–4 times for better accuracy at
different temperatures in acetone, DMF and mixture solvents and
the solubility parameters were estimated. The measured solubility
of the compound in acetone, DMF and a 1:1 mixture of acetone and
DMF solvents as a function of temperature are shown in the Fig. 1.
It was found that, the compound MPTCPP is highly soluble in
acetone and less soluble in DMF but the solubility is steadily linear
in 1:1 mixture of acetone and DMF. Hence we have chosen the
mixture of acetone and DMF (1:1 ratio) as the best solvent for
the growth of MPTCPP single crystals.
2.3. Crystal growth
Number of crystal growing methods are available to grow single
crystals, but the choice of the method is greatly depends upon the
physical and chemical properties of the material. Out of all meth-
ods, solution growth technique is inexpensive and easier. In this
method, the crystal growth is performed using a supersaturated
solution of the material with a suitable solvent. Here the choice
of the solvent is considered to be very crucial, which should have
low viscosity; material must be soluble and should not react with
the container or atmospheric gases. If a substance decomposes be-
low its melting point or undergoes a phase change, crystal growth
by solution method is the only alternate method [22].
It is known that the solubility of the compound has an influence
on the crystal size, i.e. higher the solubility smaller will be the crys-
tal size. From the solubility test it was observed that DMF is not a
suitable solvent for crystal growth for MPTCPP since its solubility is
very low even at higher temperatures. On the other hand solubility
is very high in acetone. So in the present case crystals were grown
by slow evaporation technique at room temperature using the
mixture of acetone and DMF in 1:1 ratio as solvents which gives
a moderate solubility [22]. Here a supersaturated solution of
MPTCPP was obtained by dissolving the sample in a 1:1 mixture
of acetone and DMF with continuous stirring at room temperature.
The prepared solution was filtered using filter paper, slightly
warmed and allowed to evaporate very slowly. After about
5–10 days, good quality transparent tiny crystals started growing.
In order to increase the size of these crystals further, small crystals
2. Experimental
2.1. Synthesis and characterization
The commercially available 4-methoxyacetophenone and
2,3,5-trichlorobenzaldehyde were purchased from Sigma Aldrich
Chemicals Pvt. Ltd., Bangalore. (E)-1-(4-methoxyphenyl)-3-(2,3,5-
trichlorophenyl)prop-2-en-1-one [MPTCPP] was synthesized by
adopting Claisen–Schmidt condensation reaction method [20].
Here, 0.01 mol solution of 4-methoxyacetophenone was mixed
with 0.01 mol of 2,3,5-trichlorobenzaldehyde in ethanol (20 ml)
and the mixture was treated with an aqueous solution of potas-
sium hydroxide (2 ml, 30%). This mixture was stirred well and kept
aside for 24 h. The resulting solid mass was collected by filtration
and dried. The obtained compound was purified three to four times
by re-crystallizing in ethanol. The molecular formula of MPTCPP
compound is C16H11Cl3O2 and its molecular weight is 341.60. In
order to confirm the newly synthesized compound the 1H NMR
spectra were recorded on a Bruker AV3-400 FT NMR spectrometer
operating at 400 MHz.
2.2. Solubility studies
The solubility test plays an important role in selecting the best
solvent and temperature for crystal growth. In order to optimize
the growth parameters, the solubility tests of the synthesized
compounds was determined at various temperatures, ranging from
room temperature to 55 °C in three different solvents, namely
acetone, DMF and a 1:1 mixture of acetone and DMF. Here about
15–20 ml of the solvent was taken in a clean beaker and heated
to a specific temperature. The powdered sample was added slowly
to the solvent with continuous stirring to get a saturated solution
i.e. till the compound remains un-dissolved. About 10 ml of this
clear saturated solution was transferred to a pre-weighed specific
gravity bottle and weighed it again. The weight of the solution
was measured by taking the difference between the weight of
the bottle containing the solution and the weight of the empty bot-
tle at constant temperature. The solution from the gravity bottle
was transferred to a clean beaker for evaporation to get the actual
solute present in the solution. The solute was then dried in an oven
and actual weight of the solute was measured. In this study an
electronic balance with an accuracy of 0.001 mg was used for
weighing and the temperature was maintained with a good quality
Fig. 1. The solubility curve of MPTCPP.

P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
3
were used as seeds and larger crystals were grown by slow evapo-
ration method.
determined using Meyer’s law. The thermal analysis was carried
out using SDT 600 TA instrument in the temperature range
23–500 °C at a heating rate of 10 °C/min in nitrogen atmosphere
from 23 °C to 500 °C.
3. Characterizations
4. Results and discussion
The single crystal XRD data of MPTCPP were collected on a DIP
Labo Image Plate system equipped with a normal focus, 3 kW
sealed X-ray source [graphite monochromatic Mo Ka]. Here the
4.1. 1H NMR spectra
crystal-to-detector distance was fixed at 120 mm with a detector
area of 441 ꢀ 240 mm2. The structure was solved by direct meth-
ods using SHELXS-97 [23]. The SHG efficiency of the chalcone
was determined using Kurtz and Perry powder relative SHG effi-
ciency measurement technique [24]. It consists of a Q-switched
8.0 ns Nd: YAG laser operating at 1064 nm with 10 Hz repetition
rate and delivering 20 mJ/pulse of energy. The sample and the ref-
erence urea sample, in the powder form, were filled in separate
capillary tubes. The size of the sample was kept larger than the
beam cross-section so that the radiation is completely passed
through the sample. A tight packing of the sample was ensured
with the aid of a mechanical vibrator. The capillary tube was kept
at a distance of 3 cm from the focused spot of the laser beam in or-
der to avoid any laser-induced damage on the sample. The SHG
signal from the sample was measured at an angle 90° with respect
to the laser beam direction. The fundamental light was filtered
with the aid of a monochromator. The second harmonic (SH) sig-
nals were converted into electrical signals using a photomultiplier
tube and were finally displayed on a digital storage oscilloscope.
The SHG output was averaged over 300 laser pulses. UV–Visible
absorption spectra were recorded using SHIMADZU UV-1800 spec-
trophotometer in the wavelength range 190–1000 nm. The micro
hardness of the crystal was tested using Vicker’s micohardness
device MATSUZAWA CO LTD JAPAN with CLEMEX software. The
work hardening coefficient value (n) of the grown crystal was
The 1H NMR spectrum of MPTCPP is as shown in the Fig. 2. The
spectrum shows a doublet centered at d8.19 (J = 7.2 Hz) for H5 and
H50 of 4-methoxyphenyl ring. The signal due to H6 and H60 of
4-methoxyphenyl ring is also resonated as a doublet centered at
d7.07 (J = 7.2 Hz). The spectrum also shows two separate doublets
centered at 8.114 (J = 2.4 Hz) and d7.721 (J = 2.4 Hz) for H1 and H2
of 2,3,5-trichlorophenyl moiety. The H4 and H3 protons of the
chalcone moiety resonated as two separate doublets centered at
d 7.45 and d 6.87 with a coupling constant J = 9.2 Hz for each.
The estimated strong coupling constant J = 9.2 Hz mainly repre-
sents the trans coupling of the adjacent protons, which confirms
the trans geometry of the double bond of chalcone. The protons
of methoxy group appeared as a singlet at d = 3.9 integrating for
three protons. The study reconfirms the functional groups present
in the molecule and hence the molecular structure of MPTCPP
given in Fig. 3.
4.2. Crystal structure determination
The single crystal of MPTCPP with
a
dimensions
0.3 ꢀ 0.27 ꢀ 0.25 mm3 was chosen for X-ray diffraction study.
Thirty-six frames of data were collected at room temperature by
the oscillation method. Each exposure of the image plate was set
to a period of 400 s. The successive frames were scanned in steps
Fig. 2. 1H NMR spectra of MPTCPP.

4
P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
thoxyphenyl)-2-propen-1-one [28] respectively. Fig. 4 shows the
packing of the molecule down the b axis. The dotted line represents
the intermolecular hydrogen bond of the type CAHꢂ ꢂ ꢂO. The bond
lengths and bond angles are given in Tables 2 and 3 respectively.
From the Fig. 3, it is clear that the two aromatic rings in the
molecule are linked via a ACH@CHA moiety and each ring is
twisted relative to the other by an angle 17.90(19) Å. The molecule
is therefore almost planar. The degree of planarity correlates with
the degree of p-conjugation throughout the molecule. This, in turn,
enhances the methoxy-chloro donor–acceptor interactions across
the molecule and hence, the degree of molecular charges transfer
and degree of nonlinearity. The Fig. 4 shows that the molecular
packing along b axis and it is observed that the molecular stacking
is parallel to each other both along b and c-directions. This type of
parallel stacking of molecules in two perpendicular directions is
known to give the herringbone structure. In the present case the
mean interplanar spacings between the molecules along the b
and c directions are 1.89 Å (3) and 6.307 Å (6) respectively. The for-
mer distance is extremely small and is comparable to the intermo-
lecular atomic distances indicates that the parallel molecules pack
almost directly on top of each other. According to Cole et al. [10]
such parallel and close layer-like stacking of molecules is very
favorable for the promotion of charge transfer through the lattice.
Accordingly the observed origin and high SHG efficiency of
MPTCPP crystal is understood.
Fig. 3. ORTEP diagram of the molecule with thermal ellipsoids drawn at 50%
probability.
of 5° per minute with an oscillation range of 5°. Image processing
and data reduction were done using Denzo [25] reflections were
merged with Scalepack [26]. All the frames could be indexed using
primitive monoclinic lattice. All of the non-hydrogen atoms were
revealed in the first Fourier map itself. Full-matrix least squares
refinement was done using SHELXL-97 [23] with isotropic temper-
ature factors for all the atoms. Refinement of the non-hydrogen
atoms with anisotropic parameters was started at this stage. The
hydrogen atoms were placed at chemically acceptable positions
and were allowed to ride on the parent atoms. 191 parameters
were refined with 2143 unique reflections which saturated the
residuals to R1 = 0.0316. The details of the crystal data and refine-
ment are given in Table 1.
4.3. UV–Visible studies
The recorded UV–Vis spectrum for the new compound is shown
in Fig. 5. Most of the absorption spectroscopy of organic com-
pounds are based on transitions of n or
Fig. 3 represents the ORTEP diagram of the molecule with ther-
mal ellipsoids drawn at 50% probability. The molecular structure
consists of two benzene rings linked by propen one chain at the
1,3 – position. The unsaturated keto group is in – syn-periplanar
(-sp) as indicated by the torsion angle value of ꢁ3.2(7)° for the
atoms C10AC11AC12AO13. The olefenic double bond
(C10@C11@1.332(6) Å) is in E-configuration and is Csp2 hybridized.
The dihedral angle between two benzene rings is 17.90(19) Å. This
value deviates from the values of 11.0(1) Å and 19.25(10) Å,
reported for 1-(2-hydroxy-4-methoxyphenyl)-3(2,3,4-trimethoxy-
phenyl) prop-2-one [27] and 1-(4-Methoxyphenyl)-3-(3,4-dime
p
electrons to the p⁄ excited
state which takes place in the range 200–700 nm. In this point of
view, the max absorption peak observed at 364 nm (Fig. 5) can
be assigned to n ? p⁄ transition and may be attributed to the exci-
tation in the aromatic ring and C@O group [29]. The Fig. 5 also
shows that the compound is transparent in the entire visible region
and the absorption takes place in the UV range which is the key
factor for this compound for NLO applications in the room
temperature.
Table 1
4.4. Second harmonic generation (SHG)
Crystal data and structure refinement table.
The measured SHG efficiency of MPTCPP is three times that of
urea (Table 4). The origin of the SHG in this compound can be
understood by invoking chemical structure and single crystal
XRD data. From the molecular structure (Fig. 3) it is observed that
Empirical formula
C16H11Cl3O2
Formula weight
Temperature
Wavelength
Crystal system
Space group
341.60
293(2) K
0.71073 Å
Monoclinic
Cc
Cell dimensions
a = 28.215(5) Å
b = 3.9740(4) Å
c = 16.178(3) Å
b = 124.005(4)o
1503.0(4) Å3
4
Volume
Z
Density (calculated)
Absorption coefficient
F000
Crystal size
Theta range for data collection
Index ranges
1.510 Mg/m3
0.608 mmꢁ1
696
0.3 ꢀ 0.27 ꢀ 0.25 mm3
3.5–25°
ꢁ31 P h P 32
ꢁ4 P k P 4
ꢁ18 P l P 18
2143 [R(int) = 0.000]
None
Full-matrix least-squares on F2
2143/191
1.07
Independent reflections
Absorption correction
Refinement method
Data/parameters
Goodness-of-fit on F2
Final R indices
R1 = 0.0316, wR2 = 0.0805
Largest diff. peak and hole
0.16 and ꢁ0.27e Åꢁ3
Fig. 4. The packing of the molecules down the b axis.

P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
5
Table 2
Bond lengths (Å) of MPTCPP.
Atoms
Bond length
Atoms
Bond length
Atoms
Bond length
C1AC6
C1AC2
C1ACl7
C2AC3
C3AC4
C3AC10
C4AC5
C4ACl8
C5AC6
C5ACl9
C10AC11
1.378(5)
1.380(4)
1.736(3)
1.393(4)
1.406(4)
1.467(5)
1.386(5)
1.726(3)
1.377(5)
1.734(3)
1.319(5)
C11AC12
C12AO13
C12AC14
C14AC19
C14AC15
C15AC16
C16AC17
C17AO20
C17AC18
C18AC19
O20AC21
1.487(4)
1.216(4)
1.472(5)
1.386(5)
1.406(4)
1.356(5)
1.383(5)
1.359(4)
1.382(4)
1.375(5)
1.428(4)
C2AH2
C6AH6
0.9300
0.9300
0.9300
0.9300
0.9300
0.9300
0.9300
0.9300
0.9600
0.9600
0.9600
C10AH10
C11AH11
C15AH15
C16AH16
C18AH18
C19AH19
C21AH21A
C21AH21B
C21AH21C
Table 3
Bond angles (in degrees) of MPTCPP.
Atoms
Bond angle
Atoms
Bond angle
Atoms
Bond angle
C6AC1AC2
C6AC1ACl7
C2AC1ACl7
C1AC2AC3
C2AC3AC4
C2AC3AC10
C4AC3AC10
C5AC4AC3
C5AC4ACl8
C3AC4ACl8
122.0(3)
118.6(2)
119.4(2)
120.5(3)
117.7(3)
121.9(3)
120.4(3)
120.3(3)
119.8(2)
119.9(2)
C6AC5AC4
C6AC5ACl9
C4AC5ACl9
C5AC6AC1
C11AC10AC3
C10AC11AC12
O13AC12AC14
O13AC12AC11
C14AC12AC11
C19AC14AC15
121.6(3)
118.1(2)
120.4(3)
117.9(3)
128.0(3)
120.7(3)
121.0(3)
118.6(3)
120.4(3)
116.8(3)
C19AC14AC12
C15AC14AC12
C16AC15AC14
C15AC16AC17
O20AC17AC18
O20AC17AC16
C18AC17AC16
C19AC18AC17
C18AC19AC14
C17AO20AC21
124.7(3)
118.5(3)
121.2(3)
121.0(3)
124.7(3)
116.0(3)
119.2(3)
119.4(3)
122.4(3)
118.0(3)
polarization as well as optical non-linearity. Further, the single
crystal XRD study of MPTCPP revealed that the compound crystal-
lizes in the monoclinic crystal system with a space group Cc which
is non-centrosymmetric system. This non-centrosymetric nature
justifies the existence of NLO property with in the crystal [11].
Based on the hydrogen bond also one can understand the origin
of SHG with in this crystal. The MPTCPP molecule contains a weak
electron donor (methoxy) and a weak electron acceptor (carbonyl
group), and one can expect the contribution from intermolecular
hydrogen bond interaction to the observed SHG efficiency of MPT-
CPP. Here the structure exhibits intermolecular hydrogen bonds of
the type CAHꢂ ꢂ ꢂO (C21AH21Aꢂ ꢂ ꢂO13) with the bond length of
3.451(6) Å and the angle of 166° with symmetry code x, 1 ꢁ y, 1/
2 + z. In addition to CAHꢂ ꢂ ꢂO hydrogen bond interactions, there
may be weak CAHꢂ ꢂ ꢂp bond (p is the center of the benzene ring)
intermolecular interactions in the crystal lattice, which might have
helped the MPTCPP molecules to align in head-to-tail fashion with
in the solid-state structure. Such interactions also help to extend
the molecular charge transfer with in the supramolecular realm
and lead to extended delocalization both in the ground as well as
in the excited state. This might have further, enhanced the SHG
efficiency. In addition to the SHG, these hydrogen bonds also help
in getting the stability of the crystal structure.
Fig. 5. UV–Visible spectrum of MPTCPP.
the MPTCPP molecule contains methoxy group (one electron
donating) attached to the para position of a benzene ring and three
chlorine groups attached to the other benzene ring at ortho and
meta positions. According to Zhao et al. [30] the chlorine atom
can act as both electron acceptors and electron donors (i.e.,
amphiprotic) depending upon the strength (electron donating or
accepting) of other substituent. If it is attached to a conjugated sys-
tem like phenyl ring, it releases the electrons via mesmeric effect.
Accordingly in our case, the C6H2A(Cl)3 acts as donor group due to
its mesomeric electron releasing behavior and the carbonyl group
(AC@O) present at the middle of the molecule acting as an electron
accepting group. Thus, the MPTCPP molecule possesses a DAAAD
type structure where the charge transfer takes place from the ends
of the molecule to the center. This will ensure the electronic
delocalization within the molecule and helps to possess different
4.5. The mechanical and thermal property
The hardness of the material plays a major role in device fabri-
cation. To evaluate the hardness of the present material Vickers
hardness method has been adopted. Here to find the Vicker’s micro
hardness number, several indentation were made on (1 0 0) plane
of the MPTCPP crystal. The Vicker’s micro hardness number was
then calculated using the expression [31]
H
v
¼ 1:8544P=d2kg=mm2
ð2Þ
where Hv is the Vicker’s micro hardness number in kg/mm2, P is the
applied load in gm and d is the average diagonal length of the

6
P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
Fig. 8. The TG and DTA curves of MPTCPP.
Fig. 6. The load dependence of VHN of MPTCPP.
n value from the Fig. 7, of MPTCPP is 1.48. From the careful obser-
vations on various materials, Onitsch [32] and Hanneman [33]
pointed out that, the n value lies between 1 and 1.6 for hard mate-
rials and more than1.6 for soft materials. More over if the value of n
greater than 2 the microhardness increases with increasing load.
From the present value of n, it is clear that, the n value of MPTCPP
is below 1.6 suggesting that this crystal belongs to hard material
category and hence the microhardness decreases with increase of
load (Fig. 6). This is a very interesting property for this crystal be-
cause most of the organic crystals fall under the class of soft mate-
rials having n value more than 1.6 [31,34].
Apart from the mechanical property, the thermal stability of the
crystal is also one more important criterion for device application.
In view of this the thermo gravimetric analysis (TG) and differen-
tial thermal analysis (DTA) of the crystal have been carried out
simultaneously. Here the powdered crystals of around 14–16 mg
are used as samples for the thermal analysis. The percentage of
weight loss of the sample as a function of temperature is measured
in TGA and the energy change in the sample with temperature is
monitored in DTA studies. The observed TG/DTA thermograms of
the grown crystal are shown in the Fig. 8. From the thermogram
it is observed that the mass of the MPTCPP sample remains un-
changed till a temperature 225 °C and looses its weight almost
completely around 475 °C. This variation in weight loss after
225 °C indicates the onset of decomposition of the sample and it
extends up to 475 °C. This suggests that the compound is thermally
stable even beyond the melting point (127.52 °C). The result of DTA
study shows a significant endothermic transition at 127.52 °C,
indicates the melting point of the crystal. Also, the plot shows no
endo- or exothermic transitions below 127 °C indicates the ab-
sence of other phase transition before the melting point of MPTCPP
and is stable in this region. The sharpness of the endothermic peak
shows good degree of crystallinity of the grown crystal.
Table 4
SHG efficiency of MPTCPP.
Compound Energy/
pulse
SHG signal (in
Volts)
SHG efficiency (compare to
urea)
Urea
MPTCPP
1.2–1.4 mJ
1.2–1.4 mJ
0.660
1.9
1
3
indentation in mm. The estimated load dependence of Vicker’s
hardness number is shown in Fig. 6. From the figure it is clear that
the Vicker’s hardness number decreases with increase in load and
saturated after 50 g of load. During the measurement it is observed
that the cracks with in the crystal start to develop at the load of
100 g. Following Meyer’s law, which relates the applied load to
the diagonal length of impression for plastic material, the hardening
coefficient value (n) of the grown crystal has been determined using
the relation P = Adn where P is the load, d the diagonal length of
impression, and A and n are constant physical parameters corre-
sponding to strength and plastic material properties. By plotting
log P vs. log d (Fig. 7) a straight line is obtained and the slope of this
graph is found to be the value of n. In the present case the estimated
5. Conclusion
The chalcone derivative, MPTCPP was synthesized and the sin-
gle crystals have been grown by solution growth technique at
room temperature. The functional groups present in this com-
pound are identified using NMR study. The crystal structure, space
group and the crystal parameters of MPTCPP are found out using
single crystal XRD. The MPTCPP compound has SHG efficiency of
three times that of urea. The SHG response of this crystal is
inherently dependent upon its structural attributes. The UV–Visi-
ble characteristic shows that the crystal is transparent in the entire
Fig. 7. Plot of log P vs. log d of MPTCPP single crystal.

P.C. Rajesh Kumar et al. / Journal of Molecular Structure 1005 (2011) 1–7
[12] M. Amalanathan, I. Hubert Joe, V.K. Rastogi, J. Mol. Struct. 985 (2011) 48.
7
visible range and absorption is observed in the UV region at
364 nm. The thermal and Mechanical stabilities of the crystal are
found to be good. The work hardening coefficient value (n) of the
crystal is found to be 1.48 indicates that the crystal is hard. Ther-
mal study suggests that the crystals are thermally stable in nature.
[13] K. Jagannathan, S. Kalainathan, G. Bhagavannarayana, Spectrochim. Acta Part A
73 (2009) 79.
[14] Sweta Moitra, Tanusree Kar, Journal of Cryst. Growth 310 (2008) 4539.
[15] D. Jaikumar, S. Kalainathan, G. Bhagavanarayana, J. Cryst. Growth 312 (2009)
120.
[16] G.H. Sun, X.T. Sun, Z.H. Sun, X.Q. Wang, X.J. Liu, G.H. Zhang, D. Xu, J. Cryst.
Growth 311 (2009) 3904.
[17] M. Senthil Pandian, N. Balamurugan, G. Bhagavannarayana, P. Ramasamy, J.
Cryst. Growth 310 (2008) 4143.
Acknowledgments
[18] A. Chandramohan, R. Bharathikannan, J. Chandrasekaran, P. Maadeswaran, R.
Renganathan, V. Kandavelu, J. Cryst. Growth 310 (2008) 5409.
[19] Huaihong Zhang, Yu Sun, Xiaodan Chen, Xin Yan, Baiwang Sun, J. Cryst. Growth
324 (2011) 196.
[20] D.N. Dhar, The Chemistry of Chalcones and Related Compounds, Wiley, New
York, 1981.
[21] V. Ravindrachary, Vincent Crasta, R.F. Bhajantri, Boja Poojari, J. Cryst. Growth
275 (2005) 313.
[22] J.C. Brice, Crystal Growth from Solution, North-Holland Publishing Company,
Amsterdam, 1973.
The authors are grateful to Dr. P.K. Das and the Chairman, NMR
Centre, Indian Institute of Science, Bangalore for NLO studies and
NMR facilities and Dr Boja Poojari, Dept of chemistry, Mangalore
University for NMR discussions. The authors also acknowledge
the UV–Visible facilities provided by the Head, USIC, Mangalore
University.
References
[23] G.M. Sheldrick, SHELXS-97: Program for Crystal Structure Solution, University
of Gottingen, Germany, 1997.
[24] S.K. Kurtz, T.T. Perry, J. Appl. Phys. 39 (1968) 3798.
[25] Z. Winowski, W. inor, Methods in Enzymology: Macromolecular
Crystallography, Academic Press, NY, 1997.
[26] S. Mackay, C.J. Gillmore, C. Edwards, K. Shankland, Computer Program for the
Solution and Refinement of Crystal Structures, Mac Science Japan and the
University of Glasgow, The Netherlands, 1999.
[1] D.J. Williams, ACS Symp. Ser. (1983) 233.
[2] D.J. Williams, Angew. Chem., Int. Ed. Engl. 23 (1984) 690.
[3] R.A. Hann, D. Bloor, Organic Materials for Non-linear Optics, Royal Society of
Chemistry, London, 1989.
[4] P.N. Prasad, D.J. Williams, Introduction to Nonlinear Optical Effects in Organic
Molecules and Polymers, Wiley, New York, 1991.
[27] A.S. Pandi, D. Velmurugan, S.S. Sundararaj, H.K. Fun, M.C. Bansal, Acta
Crystallogr. C 59 (2003) 302.
[28] V. Shettigar, P.S. Patil, S. Naveen, S.M. Dharmaprakash, M.A. Sridhar, J.
Shashidhara Prasad, J. Cryst. Growth 295 (2006) 44.
[29] Vincent Crasta, V. Ravindrachary, R.F. Bhajantri, Richard Gonsalves, J. Cryst.
Growth 267 (2004) 129.
[5] P.A. Franken, A.E. Hill, C.W. Peters, G. Weinreich, Phys. Rev. Lett. 7 (1961) 118.
[6] G. Anandha Babu, S. Sreedhar, S. Venugopal Rao, P. Ramasamy, J. Cryst. Growth
312 (2010) 1957.
[7] J. Badan, R. Hierle, A. Perigand, J. Zyss, in: D.J. Williams (Ed.), Nonlinear Optical
Properties of Organic Molecules and Polymeric Materials, American Chemical
Society, Washington, DC, 1993.
[30] B. Zhao, Y. Wu, Z.-H. Zhou, W.-Q. Lu, C.-Y. Chen, Appl. Phys. B 70 (2000) 601.
[31] A.S. Haja Hameed, G. Ravi, R. Dhanesekaran, P. Ramasamy, J. Cryst. Growth 212
(2000) 227.
[8] D.S. Chemla, J. Zyss, Non-linear Optical Properties of Organic Molecules and
Crystals, Academic Press, London, 1987.
[9] J. Indira, P. Prakash Karat, B.K. Sarogini, J. Cryst. Growth 242 (2002) 209.
[10] J.M. Cole, A. Judith, K. Howard, Garry J. McIntyre, Acta Crystallogr. B 57 (2001)
410.
[32] E.M. Onitsch, Mikroskopie 2 (1947) 131.
[33] M. Hanneman, Metallurgia Manchu 23 (1941) 135.
[34] Junko Yabuzaki, Yoshinori Takahashi, Hiroaki Adachi, Yusuke Mori, Takatomo
Sasaki, Bull. Mater. Sci. 22 (1999) 11.
[11] P. Srinivasan, T. Kanagasekaran, R. Gopalakrishnan, Cryst. Growth Des.
(2008) 2340.
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