Concomitance, Reversibility, and Switching Ability of Centrosymmetric and Non-Centrosymmetric Crystal Forms: Polymorphism in an Organic Nonlinear Optical Material

Article abstract of DOI:10.1021/acs.cgd.7b01560

Reversibility between two concomitant polymorphs and their switching ability is demonstrated for the novel organic nonlinear optical (NLO) material Z-3-(3-methoxyphynyl)-2-(4-nitrophenyl)acrylonitrile. The appearances of their concomitant as well as exclu

Full text of DOI:10.1021/acs.cgd.7b01560

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Article
Concomitance, reversibility and switching ability of centrosymmetric and
non-centrosymmetric crystal forms: Polymorphism in an organic NLO material
Kunal K. Jha, Sanjay Dutta, and Parthapratim Munshi
Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.7b01560 • Publication Date (Web): 20 Dec 2017
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Concomitance, reversibility and switching ability of
centrosymmetric and nonꢀcentrosymmetric crystal
forms: Polymorphism in an organic NLO material
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Kunal K. Jha, Sanjay Dutta and Parthapratim Munshi*
Chemical and Biological Crystallography Laboratory, Department of Chemistry, School of
Natural Science, Shiv Nadar University, Tehsil Dadri, Uttar Pradeshꢀ 201314, India.
Eꢀmail: parthapratim.munshi@snu.edu.in
ABSTRACT
Reversibility between two concomitant polymorphs and their switching ability is demonstrated
for the novel organic NLO material, Zꢀ3ꢀ(3ꢀmethoxyphynyl)ꢀ2ꢀ(4ꢀnitrophenyl)acrylonitrile. The
appearances of their concomitant as well as exclusive polymorphic forms were discovered upon
systematic crystallization experiments using various solvents. Determination of Xꢀray crystal
structures confirmed that the polymorphs crystalize in centrosymmetric (P21/n) and nonꢀ
centrosymmetric (Fdd2) space groups. A search using the Cambridge Structural Database
revealed that there exist only 10 such polymorphic pairs. A reversible phase transitions and the
switching ability between the polymorphs can be achieved via both heat and solvents as stimuli.
Structural analysis confirmed that the polymorphs have 2D similarity. Further, quantitative and
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qualitative analysis of interaction energies based on the UNI force field and energy frameworks
indicate that they possess very similar energies, although the centrosymmetric form is slightly
lower in energy. A comparably high value of SHG activity and the NLO properties as estimated
based on gasꢀphase and inꢀcrystal calculations suggest that the nonꢀcentrosymmetric form could
be a potential NLO material. To the best of our knowledge, this study is the rarest of its kind to
show the reversibility and switching ability between centrosymmetric and nonꢀcentrosymmetric
polymorphic phases in an organic material, induced via both thermal and solvent stimuli.
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INTRODUCTION
Focus on materials science research is slowly but steadily shifting from inorganic and
organometallic systems to organic materials.1–7 Interest in organic materials has been increasing
gradually due to their design flexibility, low molecular weight, low cost and ecoꢀfriendly
nature.8ꢀ9 Certain classes of organic compounds in their solidꢀstate respond to external stimuli
and find myriad of applications in optoelectronics, nonꢀlinear optics (NLO), ferroelectrics,
semiconductors etc.10–13 However, most of these properties demand not only the presence of nonꢀ
centrosymmetric phases but also the existence of polar phases of the materials in their crystalline
form. But controlling the nonꢀcentrosymmetric phase remains a key challenge for designing such
materials.14–17 While crystal symmetry is mainly governed by the molecular packing in the
crystal lattice the external parameters such as crystallizing solvents, pressure, thermal stimuli etc.
play crucial role in controlling the desired phases of the materials. In the presence of such
stimuli, the materials may even undergo changes between different polymorphic modifications –
existence of at least two different crystal structures of the same material.18 While the
phenomenon of polymorphism is not uncommon in molecular crystals and it is predominantly
discovered in pharmaceutical compounds, its existence in organic materials with responsive
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characteristics is scarce.19–21 Moreover, the ability of appearance of two polymorphs
simultaneously in a given condition, i.e. concomitant polymorphs22 and their reversible switching
between centrosymmetric and nonꢀcentrosymmetric forms in such responsive organic materials
are extremely rare.23,24
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Switching ability in organic materials is employed for various applications in material
industries, in the field of fluorescence, live cell imaging microscopy, environmental interface
cutter, optoelectronics, photonic devices, etc.25–28 The common approaches for attaining
switching materials include introduction of conformational modifications in the
πꢀconjugated
donorꢀacceptor system, photochemical reactions under UVꢀVis light and probing samples under
thermal stimulus etc.29,30 Switching of centrosymmetric to nonꢀcentrosymmetric or polar to nonꢀ
polar form can occur in their solid state or in crystals. Although there are some reports on such
switching upon UV light irradiation31,32 but reports either induced via solvent33,34 or
temperature35 are very rare. To the best of our knowledge, centrosymmetric to nonꢀ
centrosymmetric switching and their reversibility, induced by both solvent and temperature as
stimuli and in a single organic material has not been reported before. Moreover, interconversion
between polymorphic forms are uncommon.36 Formation of coꢀcrystals and organicꢀinorganic
hybrid structures were also investigated to achieve better switching ability and reversibility in
NLO materials.37 Recently, single component plastic crystals have been investigated and found
to display record high on/off contrast.38 Considering only organic structures, search using CSD
(version 5.38, update May 2017)39,40 revealed 115,443 (~13%, total number of reported
structures is 892,156) structures belong to the nonꢀcentrosymmetric space groups, out of which
only 4167 (~0.46%) structures exist in polymorphic form. Further, occurrences of concomitant
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polymorphs in organic systems are limited22 and the existence of centrosymmetric and nonꢀ
centrosymmetric forms as concomitant polymorphs is also rare.41,42
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The πꢀconjugated organic scaffolds such as stilbene and chalcone are known to exhibit
polymorphic behavior and occasionally exist in nonꢀcentrosymmetric forms, which give rise to
SHG effect.43–45 Careful and intuitive substitution of donor and acceptor group in a πꢀconjugated
organic scaffolds such as MMONS and CMONS led to highly NLO active materials with
different morphology and structures when crystallized using different solvents.43,44
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Here we report the systematic investigations of (i) two concomitant polymorphs of Zꢀ3ꢀ(3ꢀ
methoxyphynyl)ꢀ2ꢀ(4ꢀnitrophenyl)acrylonitrile (Scheme I) and discovered their existence in
centrosymmetric and nonꢀcentrosymmetric space groups, (ii) their reversible phase transitions in
the presence of both solvents and heat as stimuli, (iii) the differences and degree of similarities
between the two polymorphic crystal structures (iv) quantitative and qualitative pictures of their
interaction energies and (v) NLO properties of the nonꢀcentrosymmetric polymorph.
Scheme I. Chemical diagram of Zꢀ3ꢀ(3ꢀmethoxyphenyl)ꢀ2ꢀ(4ꢀnitrophenyl)acrylonitrile.
EXPERIMENTAL SECTION
Synthesis. All the reagents used for the synthesis of Zꢀ3ꢀ(3ꢀmethoxyphynyl)ꢀ2ꢀ(4ꢀ
nitrophenyl)acrylonitrile (3-OMe-CNS) were procured from SigmaꢀAldrich. The reagents were
used without further purifications. 3-OMe-CNS was prepared by Knoevenagel condensation of
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4ꢀnitrophenylacetonitrile and 3ꢀmethoxybenzaldehyde using piperidine as basic catalyst in
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ethanol at 70°C for three hours as reported earlier (Scheme SI).46,47 Compound thus formed was
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purified by column chromatography and characterized via FTꢀIR, H, 13C NMR and HRMS
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(Figs. S1-S3).
Crystallization. A range of HPLC grade solvents were employed for growing the crystals of 3-
OMe-CNS using slow evaporation method at room temperature (22ꢀ25°C) and low temperature
(3ꢀ6°C). A systematic crystallization experiment of 3-OMe-CNS at both low temperature (LT)
and room temperature (RT) using the solvents as listed in Table 1 provided crystals with two
morphologies; needles and plates. Crystallizations using chloroform and tetrahydrofuran (THF)
as solvents resulted in the appearance of both morphologies together, i.e. concomitantly.
However, at RT and using THF only the plate form was obtained. Further, optimization of
crystallization conditions afforded the growth of the individual forms. High quality singleꢀ
crystals grown using chloroform were used for the Xꢀray diffraction experiment. The crystal
morphologies as captured using Olympus SC30 polarizing microscope are shown in Figure 1.
Table 1. Details of crystallization experiments.
Solvent(s)
Temperature
Crystal morphology
Chloroform
LT
RT
LT
RT
LT
RT
LT
plate/needlea
plate/needlea
Acetone
Needle
Needle
plate
“
Dichloromethane
1,4ꢀDioxane
“
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RT
LT
RT
LT
RT
LT
RT
RT
LT
RT
RT
“
Toluene
“
“
Ethylꢀacetate
Tetrahydrofuran
“
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“
plate/needlea
plate
Dimethyl Sulfoxide
Acetonitrile
plate
Needle
Needle
plate
2ꢀPropanol
aconcomitant polymorphs
Figure 1. Optical images of needle (left), concomitant (middle) and plate (right) form crystals.
X-ray Crystallography. Singleꢀcrystal Xꢀray diffraction data on both polymorphs were
collected using D8 Venture Bruker diffractometer equipped with a PHOTON 100 CMOS
detector. Crystals were cooled to 100K under liquid nitrogen flow using an Oxford Cryosystems
nitrogen gas flowꢀcooling device. Mo Kα radiation (λ=0.71073 Å) was used for data collection
using phi (ϕ) and omega (ω) scan strategy. The crystal to detector distance was set to 50 mm.
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Cell measurement, data collection, integration and scaling were done using the APEX3
software.48 The data was processed using SAINT49 and absorption correction was done using
SADABS50 program integrated in APEX3. The structure was solved using SHELXT program
and refined within the XSHELL graphic interface.51 The nonꢀH atoms were located in successive
difference Fourier syntheses and refined with anisotropic thermal parameters. All Hꢀatoms were
placed at the calculated positions and refined using a riding model with appropriate HFIX
commands.
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Powder Xꢀray Diffraction (PXRD) patterns for each polymorphic form were recorded on
a Rigaku Miniflex 600 diffractometer using parallel beam geometry and Cu Kα radiation. The
powder samples were prepared after grinding the respective polymorphic crystal forms.
Thermal Characterizations and NLO Measurement. Differential Scanning Calorimetry
(DSC) measurements on each polymorphic crystal were carried out using Mettler Toledo DSC3
instrument under nitrogen gas atmosphere. Hot Stage Microscopy (HSM) studies on each crystal
form were carried out using Nikon polarizing microscope CFI60 infinity, equipped with heating
stage LTS420. Linksys software was used for image grabbing and monitoring the sample
temperatures.
NLO activity measurement was carried out using Spectre Physics instrument equipped
with INDI LASER (Nd:Yag Laser 1064 nm) at repetition rate of 10 Hz and pulse width of 8 ns.
THEORETICAL SECTION
NLO property calculations
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The molecular gasꢀphase dipole moment (ꢀ), linear polarizability (α) and static first
hyperpolarizability (β) values were estimated based on crystal geometry using Gaussian 09.52
The keyword ‘Polar = Enonly’ was used for α and β calculation. The hybrid functional, M05ꢀ
2X53 which is widely used54,55 for such calculations in conjugated systems, was also used here
with 6ꢀ31+G* basis set. The β tensor components as obtained from above calculation was used to
determine βtotal as given by the following expression,
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βtot = [(βxxx + βxyy + βxzz)2 + (βyyy + βyzz + βyxx)2 + (βzzz + βzxx + βzyy)2]1/2
The program CRYSTAL1456 was used to perform a singleꢀpoint periodic theoretical
calculations at the B3LYP57 level and 6ꢀ31G** basis set based on the experimental geometry of
the non-centric polymorph of 3-OMe-CNS. Grimme’s dispersion function (D2)58 was also
taken in to account for this calculation. Given the nonstandard space group Fdd2 and the need to
accommodate all 16 molecules in the unit cell, the conventional supercell was generated using
the keyword SUPERCON. The keywords CPKS (Couple Perturbed KohnꢀSham) along with
THIRD (energy derivatives up to the third order) and both ANDERSON and BROYDEN (for
mixing of KS matrix derivatives) were used to perform the inꢀcrystal α, β and second order
nonlinear susceptibility (χ2). For smooth convergence, the TOLALPHA was set to 4. The
shrinking factors were set at 4. The accuracy of the calculation of the bielectronic Coulomb and
exchange series were controlled by using the keyword ITOLINTEG with ITOL1 = ITOL2 =
ITOL3 = ITOL4 = 6 and ITOL5 = 14. For faster convergence, the level shifter value was set
equal to 0.6 Hartree. The periodic wavefunction obtained upon convergence (10ꢀ8) of energy was
used to calculate the inꢀcrystal properties (α, β and χ2). The computed properties were compared
with that of urea.
Results and Discussion
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3-OMe-CNS ꢀ a cyano substituted nitro stilbene derivative, belongs to the family of donorꢀ
acceptor πꢀconjugated systems. The compound as shown in Scheme I has a πꢀconjugated
stilbene core and one end, which contains one –NO2 group as an acceptor. At the other end at the
meta position it has one –OMe group as a donor. There is also one moderate acceptor ꢀCN group
attached next to the C=C bond. These specific arrangements make 3-OMe-CNS a ‘pushꢀpull’
chromophore.
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Characterizations of polymorphs
Singleꢀcrystal Xꢀray diffraction experiment on crystals with plate morphology confirmed
that these crystals belong to orthorhombic system with nonꢀcentrosymmetric space group, Fdd2
and the crystals with needle morphology belong to a monoclinic system with centrosymmetric
space group, P21/n. Here after we identify form Fdd2 as non-centric and form P21/n as centric.
Detailed crystallographic data of these two concomitant polymorphs are summarized in Table 2.
Search using CSD (version 5.38, update May 2017, Table S1, ESI) revealed that there are only
1172 (0.13%) organic structures reported in Fdd2 space group, out of which only 54 unique
structures exist in polymorphic forms. The search further shows that only 10 of these
polymorphs exist as polymorphic pairs together with space group P21/n. The same atomic
numbering scheme is followed for both crystal forms as depicted in Figure 2. In both
polymorphs the molecule is found to adopt a planar geometry. Further, no conformational
changes were noticed between the molecules in these two polymorphic forms (Figure 2).
Table 2: Single crystal Xꢀray diffraction data and refinement parameters
Compound
Centric
Nonꢀcentric
Plate
Morphology
Needle
Chemical Formula
C16 H12 N2 O3
C16 H12 N2 O3
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Formula Weight
Crystal Size (mm)
Space Group
280.28
280.28
0.026 x 0.057 x 0.283
P21/n
0.049 x 0.160 x 0.243
Fdd2
9
Temperature/K
a(Å)
100(2)
100(2)
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6.8818(3)
30.0658(11)
7.0543(3)
116.826(1)
1302.50(9); 4
1.429
12.6352(7)
59.580(3)
6.8942(4)
90
b(Å)
c(Å)
β(°)
Volume/ Å3; Z
Density/g cmꢀ3
F(000)
5190.00(5); 16
1.435
584
2336
Absorption Coefficient /mmꢀ1
0.101
0.101
Tmin, Tmax
0.972, 0.997
0.0626
0.927, 0.988
0.0438
R(merge)
Measured Reflections
Independent Reflections
No. of parameters
R(F2), Rw(F2)
Goodness of fit (S)
ꢁρmax/e Åꢀ3, ꢁρmin/e Åꢀ3
22315
16786
2655
2624
191
191
0.0419, 0.0897
1.067
0.0371, 0.0749
1.101
0.284, ꢀ0.302
0.155, ꢀ0.265
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Figure 2: Overlay of centric and non-centric forms drawn with respect to plane containing N2,
C7 and C9 atoms.
Both polymorphic forms were further characterized using various techniques such as solid
state FTꢀIR, powder Xꢀray diffraction (PXRD), differential scanning calorimetry (DSC) and hot
stage microscopy (HSM). In order to check the purity, and for accurate identification of phase
differences the singleꢀcrystals of the two forms were carefully separated upon checking their unit
cell parameters.
The crystals were then crushed before performing the FTꢀIR and UV experiments. The
recorded FTꢀIR spectra (Figure S1, ESI) on the two forms displayed an identical pattern. The
absorption maximum (λmax) as recorded from the UVꢀVis spectra are almost identical; 342.89 nm
and 342.13 nm for the centric and non-centric forms, respectively (Figure S4, ESI). This
suggests that the two polymorphs possess the same absorptions in solution. The λmax values
suggest that these polymorphs belong to the family of ‘yellow material’.59,60
PXRD experiments were performed on pure phases of crystalline samples at room
temperature. The scan rates used for this experiments were 1°/min with 0.02° step in 2θ. The
comparison of experimental PXRD patterns clearly indicates the phase differences (e.g. peaks at
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2θ = ~16°for the non-centric form and 2θ = ~18.5°for centric form) between the centric and the
non-centric polymorphs (Figure 3). The PXRD patterns were also compared with their
corresponding simulated PXRD patterns as generated from the respective singleꢀcrystal
structures determined at room temperature. The comparison displayed good agreement between
the observed and the predicted patterns of each form (Figure S5, ESI).
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Figure 3. Overlay of experimental PXRD patterns of centric and non-centric polymorphs
Thermally induced phase reversal
Further, both crystal forms were subjected to thermal characterization via a DSC experiment.
The pure single crystal samples were heated at the rate of 5°C/min from 25ꢀ250°C and cooled
down to room temperature in two successive cycles. The sharp melting and crystallization peaks
as appeared during the heating and cooling cycles clearly indicate that the polymorphs exist in
their pure crystalline forms (Figure 4). The non-centric form displayed slightly higher melting
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point (195.04°C) compared to that of centric form (194.23°C). Interestingly, during the second
heating cycle, the melting peak (194.04°C) of the non-centric form is found to be very close to
the melting peak of centric form recorded during the first heating cycle. This observation
suggests that the non-centric form transforms to the centric form upon melting and
recrystallization.
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Figure 4. DSC traces for centric and non-centric polymorphs.
Further, these phase changes were monitored and visualized via complementary HSM
technique on the pure singleꢀcrystals of the two polymorphs. The change in the morphology of
the centric form was first noticed at around 195°C and finally melted at around 200°C (Figure
5). Whereas for the non-centric form the first change was observed at around 190°C. It finally
melted also at around 200°C. During the cooling cycle for the centric form the compound
appeared to crystallize at around 172°C, the corresponding temperature for the non-centric form
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was at around 180°C. The melting and cooling steps as observed in HSM correlate well with the
results obtained from the DSC experiment. In order to confirm their phases, crystals obtained at
the end of HSM experiments were subjected to unitꢀcell determination by Xꢀray diffraction.
Interestingly, the cellꢀparameters of both the crystals were found to match those of the non-
centric form (Table S2). This confirms that in case of HSM the centric form converts to its
non-centric form.
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Figure 5. HSM images of centric and nonꢀcentric forms.
Furthermore, we performed inꢁsitu crystallization experiment. For this purpose, we chose
singleꢀcrystals of the centric form and subjected to heating and cooling under the cryoꢀstream
while mounted in a capillary and placed on the goniometer. The unitꢀcell determination using Xꢀ
ray diffraction on the recrystallized sample from its melt confirmed that the crystal belonged to
the non-centric form, which is in accordance with the HSM experiment as discussed above.
Unfortunately, we could not confirm the reverse process by performing the same experiment on
a non-centric crystal. However, the results from DSC experiment as discussed earlier
demonstrates the occurrence of a reverse process.
Solvent mediated phase reversal
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Additionally, the reversible transformation of the polymorphic forms was investigated via
systematic solvent exchange experiments. For this purpose, the crystals with needle morphology
(centric form) were dissolved and recrystallized from the solvents in which the crystals with
plate morphologies (non-centric form) were obtained and vice versa. The outcomes of the
recrystallization experiments are summarized in Table 4. From visual inspection as well as upon
determining their cell parameters it was confirmed that the two forms also undergo reversible
phase transitions in the presence of appropriate solvent as stimulus. To the best of our
knowledge, this experiment is the first of its kind to demonstrate solvent mediated phase reversal
of polymorphic forms.
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Collating all these results from DSC, HSM, inꢁsitu recrystallization via heating and cooling
and the solvent exchange experiments we conclude that the compound 3-OMe-CNS undergoes
reversible polymorphic phase transitions. The phase reversal process under various stimuli as
discussed above is summarized in Figure 6.
Table 4. Reꢀcrystallization of polymorphic forms using solvent exchange experiments.
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Figure 6. Summary of phase changes using both heat and solvent as stimuli.
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Molecular packing and intermolecular interactions
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Molecular packing diagrams as displayed in Figure 7 show that the molecules in both centric
and non-centric forms arrange in a similar brick stacking like pattern. The molecules are
essentially held together in their crystal lattice via π•••π and CꢀH•••O interactions. The interplanar
distance were found to be 3.28 Å and 3.27 Å for centric and non-centric form, respectively.
Further, close inspection of the monolayer packing in the two forms indicate that there is a
similarity of molecular orientation but overall the interactions differ significantly (Figure 8). The
similarity of orientation of the molecule in the two forms within their unitꢀcell is also shown in
Figure S6. In case of centric form two adjacent molecules within the monolayer are arranged in
such way along the bꢀaxis that the ꢀCN groups are facing opposite to each other. Whereas in the
case of non-centric form the ꢀCN groups of the corresponding molecules are oriented in the
same direction. In both forms the molecules are held together via C(Ar)ꢀH•••O, C(sp3)ꢀH•••O,
C(Ar)ꢀH•••N and C(sp2)ꢀH•••N interactions. However, subtle differences in their interaction
patterns between the two forms are evident from Figure 8.
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Figure 7. Packing diagrams of centric form, viewed down the aꢀaxis (above) and non-centric
form, viewed down the cꢀaxis (bellow). The color codes for different atom types are also given.
The shaded boxes highlights the similarity of stacking of molecules in (a) and (b).
Figure 8. Monolayer packing diagram of (a) centric form viewed down cꢀaxis, (b) non-centric
form viewed down aꢀaxis. The shaded boxes highlights the similarity of molecular orientation in
(a) and (b).
Additionally, in order to visualize and quantify the subtle differences in intermolecular
contacts between the two polymorphs, Hirshfeld surface analysis61 was performed based on their
crystal geometries using CrystalExplorer 3.1.62 The Hirshfeld surface based on dnorm as drawn on
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a molecule in the centric form displays a greater number of contact points compared to that of
the non-centric form (Figure 9). The subtle differences in the surface contact area (red and
white regions) in both forms are also highlighted. Red surfaces are the indication of deeper
interpenetrations of the molecular surfaces and white ones are due to the lighter
interpenetrations.
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Figure 9. dnorm mapped on the Hirshfeld surface of centric (left) and non-centric (right) forms.
Further, the interaction lengths are highlighted via 2D fingerprint plots as shown in Figure 10.
The fingerprint plots reveal slightly shorter H•••H (2.2 Å vs 2.5 Å) and O•••H (2.3 Å vs 2.5 Å)
contacts in the case of the non-centric form in compared to the centric forms. The overall
intermolecular interactions in these two forms are further quantified based on the percentage
contribution of intermolecular interactions extracted from the corresponding fingerprint plots and
displayed in a form of pieꢀchart (Figure 11). The H•••H and O•••H contacts together contribute
nearly 56% of the total interactions present in their crystal structures. About 1% contribution
differences of C•••H and C•••C interactions are noticed between the centric and non-centric
forms. Overall, the percentage contributions to the Hirshfeld surface area due to the different
types of intermolecular interactions are found to be almost similar in both forms.
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Figure 10. Hirshfeld surface associated fingerprints for centric and non-centric polymorphs.
Figure 11. Percentage contribution to the Hirshfeld surface area due to the various
intermolecular interactions in the centric and non-centric forms.
Structural similarity relationship
Further, in order to quantify the similarity relationship between these two reversible
concomitant polymorphic structures, an XPac63 analysis was performed based on the
“supramolecular construct” concept, which implies spatial arrangement of molecules in crystals.
Although the structural similarities using XPac are traditionally deduced for whole 3D structures,
they are also interpreted for 2D molecular layers of the crystal structures.64,65 In this case, the
analysis revealed that these two polymorphs possess 2D similarity with a dissimilarity index of
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1. The values of the stretch parameter (0.06), the change in angles (ꢁa = 0.6°) and a change in
plane angles (0.9°) obtained by comparison between the two polymorphs are well within the
similarity limits as reported earlier.64, 65 This analysis suggests that spatial arrangements of the
molecules forming the monolayers are identical in both polymorphic forms. This is in
accordance with the molecular packing analysis as discussed above (Figures 7 and 8). The
relevant plots from XPac analysis are given in Figure S7 in ESI.
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Intermolecular interaction energies
Energetic stability of these two polymorphic forms was determined by performing interaction
energy calculations based on both energy frameworks66 as constructed using the program
CrystalExplorer 3.1 (details are given in ESI) and also using the UNI force field as implemented
in the program Mercury.67
The color coded cluster of the molecules and the energy profiles along with the values of
interaction energies as calculated between the molecular pairs in each polymorphic crystal form
are given in Figure S8 and Table S3 in the ESI, respectively. For this purpose, all the hydrogen
bond distances were normalized to 1.083 Å and scale factor value was set to the default value of
1.0.68 The energy frameworks for the centric and the non-centric forms appeared to be similar
when viewed down the cꢀaxis and aꢀaxis, respectively (Figure 12). The corresponding views in
other directions for both forms are given in Figure S9. The energy frameworks clearly show that
the molecules in the respective crystal forms are held via strings (represent weaker interaction
energy), rods (represent moderate interaction energy) and cross bars (represent strong interaction
energy), forming triangular or quadrilateral frameworks. The distinct energy frameworks are
noticed at the bottom area of the respective forms; the centric form displays a triangular
framework while the non-centric form displayed a quadrilateral framework (Figure 12). While
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the non-centric form has slightly higher electrostatic interaction energy, the centric form is
having a higher dispersion energy. Overall, the centric form has slightly lower interaction
energy (ꢀ146.6 kJ molꢀ1) compared to that of the non-centric form (ꢀ144.8 kJ molꢀ1).
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Figure 12: Energy frameworks corresponding to different energy components and total
interaction energy of the centric (above) and the non-centric (below) forms. Red, green and
blue color codes represent electrostatic (Eele), dispersion (Edis) and the total (Etot) interaction
energies, respectively.
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Further, the intermolecular interaction energies as calculated based on the UNI force field are
found to follow a similar trend as those observed from the energy framework analysis. Once
again the centric form is found to have a slightly lower interaction energy (ꢀ172.3 kJ molꢀ1) than
that of the non-centric form (ꢀ170.6 kJ molꢀ1).
The comparable interaction energies explain the occurrence of concomitant polymorphs with
nearly equal melting points. These results further suggest that the polymorphs with concomitance
characteristics and have almost equal energies can easily alter their phases in the presence of
thermal and solvent stimuli as depicted in Figure 6.
NLO properties of non-centric form
In order to explore the potentiality of the non-centric form as an NLO material, we measured
SHG activity on a crushed homogeneous powder sample of 3-OMe-CNS crystals using Perryꢀ
Kurtz method.69 The SHG activity results were then compared with the standard samples urea
and KDP. The experimental SHG activity of the non-centric form of 3-OMe-CNS was found to
be of about three times and 1.4 times higher than that of KDP and urea, respectively (Table 5).
Table 5. Comparison of powder SHG activities
Sample
KDP
Signal (mv)
SHG x Urea
0.45
SHG x KDP
1.00
55
Urea
122
1.00
2.21
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3ꢀOMeꢀCNS (nonꢀcentric)
168
1.37
3.05
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Further, molecular gasꢀphase dipole moment (ꢀ), the linear polarizability (α) and the static first
hyperpolarizability (β) values as estimated based on crystal geometry and using Gaussian 09[52]
are listed in Table 6. Compared to urea, 3-OMe-CNS is estimated to have about 1.5 times higher
dipole moment. Linear polarizability (α) and static first hyperpolarizability (β) values were
estimated to be about seven times and 175 times higher than those of urea, respectively.
The inꢀcrystal NLO property values of αtotal, βtotal, and χ2 tensor components as estimated based
on periodic calculations using CRYSTAL1456 are listed in Table 7. The promising values clearly
suggest that the non-centric form of 3-OMe-CNS is indeed a potential NLO material.
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Table 6. Gasꢀphase linear and nonꢀlinear properties.
Compound
Gas phase (M05ꢀ2X/6ꢀ31+G*)
Dipole moment (ꢀ) Polarizability (α)
Hyperꢀpolarizability (β)*Eꢀ30
(Debye)
5.03
(au)
(esu)
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Urea
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222.19
3ꢀOMeꢀCNS
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33.40
Table 7. Inꢀcrystal linear and nonꢀlinear properties.
Compound
Urea
Inꢀcrystal (B3LYP/6ꢀ31G**)
χ2 χ2 χ2 χ2
αtotal
(au)
βtotal χ2
(esu)
χ2
χ2
(au)
χ2
(au)
χ2
(au)
χ2
zzz
(au)
xxx
(au)
xxy
xxz
xyy
xyz
xzz
yyy
yyz
xzz
(au)
(au)
(au)
(au)
(au)
55.57
0.99
0
0
0
0
ꢀ
0
0
0
0
0
0.74
3ꢀOMeꢀ
CNS
2359.95 55.15 0
0
0.15 0
0
0
0
3.05 0
ꢀ
2.06
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Conclusion
As part of this study we discovered two concomitant polymorphs of a novel organic material,
Zꢀ3ꢀ(3ꢀmethoxyphynyl)ꢀ2ꢀ(4ꢀnitrophenyl)acrylonitrile and performed systematic
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characterizations to investigate their important properties. Careful crystallization experiments
using a variety of solvents resulted in obtaining their exclusive forms as well. Singleꢀcrystal Xꢀ
ray diffraction experiments revealed that the polymorphs crystallize in centrosymmetric space
group P21/n and the nonꢀcentrosymmetric space group Fdd2. The PXRD patterns recorded on
the respective forms also confirmed their phase differences. FTꢀIR and UVꢀVis spectra of these
two concomitant polymorphs appeared to be almost indistinguishable. The sharp melting points
as recorded using DSC experiment suggested that the polymorphic forms exist as pure phases.
Collating the results from DSC, complementary HSM, inꢁsitu recrystallization via heating and
cooling and solvent exchange experiments we conclude that the compound 3-OMe-CNS has
switching ability between its centric and non-centric forms and they undergo reversible phase
transitions. To the best of our knowledge, this is the first report on a solventꢀexchange
experiment for reversibility controlling between polymorphic forms. Detailed structural analyses
based on both molecular packing and the ‘supramolecular construct’ confirmed that the
polymorphs possess 2D similarity. The quantitative and qualitative analyses of interaction
energies based on the UNI force field and the energy frameworks, respectively, indicated that the
concomitant polymorphs exist with almost equal energies. However, centric form is found to
have a slightly higher interaction energy than the non-centric form. The high value of SHG
activity and the NLO properties as estimated based on the gasꢀphase and inꢀcrystal calculations
clearly suggests that the non-centric form is a highly NLO active material may find potential
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applications. The compound 3-OMe-CNS can also be used as a switching organic material. To
the best of our knowledge, this study is first of its kind to show the reversibility and switching
ability of polymorphic phases in an organic material, induced via both thermal and solvent
stimuli.
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Supplementary Information
The Supporting Information is available free of charge on the ACS Publications website. The
information contains the general experimental procedures for characterization of compound by
FTꢀIR, NMR, UVꢀVis and HRMS experimental techniques and the corresponding spectra,
synthesis scheme, the details of CSD search, PXRD patterns, Unitꢀcell parameters from HSM,
Molecular orientation in the unitꢀcells, XPac analysis and interaction energy calculations.
Corresponding Author
Parthapratim Munshi, Eꢀmail: parthapratim.munshi@snu.edu.in
Author Contributions
The manuscript was written through contributions of all authors. All authors have given approval
to the final version of the manuscript.
Acknowledgements
We thank Shiv Nadar University for research facilities, infrastructure and funding and for
research fellowships to KKJ and SD. We are grateful to Prof. Rupamanjari Ghosh for her
encouragements and kind supports. We are thankful to Prof. A. Ramanan and Mr. Vineet for
their help with the PXRD experiments.
References
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(1)
(2)
Matulková, I.; Cihelka, J.; Pojarová, M.; Fejfarová, K.; Dušek, M.; Vaněk, P.; Kroupa, J.;
Krupková, R.; Fábry, J.; Němec, I. CrystEngComm 2012, 14, 4625–4636.
Liang, F.; Kang, L.; Zhang, X.; Lee, M.ꢀH.; Lin, Z.; Wu, Y. Cryst. Growth Des. 2017, 17,
10
11
12
13
14
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16
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18
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20
21
22
23
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27
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29
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31
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51
52
53
54
55
56
57
58
59
60
4015ꢀ4020
(3)
(4)
Halasyamani, P. S.; Zhang, W. Inorg. Chem. 2017, 56, 12077ꢀ12085.
Garcia, M. H.; Mendes, P. J.; Florindo, P.; Silva, T. In AIP Conference Proceedings;
2015; Vol. 1642, pp 514–517.
(5)
(6)
Nayar, C. R.; Ravikumar, R. J. Coord. Chem. 2014, 67, 1–16.
Maury, O.; Le Bozec, H. In Molecular Materials; Bruce, D. W., O'Hare, D., Walton, R. I.,
Eds.; John Wiley & Sons, Ltd. 2010, Chapter 1, pp 1ꢀ53.
(7)
Humphrey, M. G.; Cifuentes, M. P.; Samoc, M. In Molecular Organometallic Materials
for Optics; Springer, 2010; pp 57–73.
(8)
(9)
Williams, D. J. Angew. Chemie Int. Ed. English 1984, 23, 690–703.
Shirota, Y. J. Mater. Chem. 2000, 10, 1–25.
(10) Zhang, G.; Lu, J.; Sabat, M.; Fraser, C. L. J. Am. Chem. Soc. 2010, 132, 2160–2162.
(11) Shi, C.; Guo, Z.; Yan, Y.; Zhu, S.; Xie, Y.; Zhao, Y. S.; Zhu, W.; Tian, H. ACS Appl.
Mater. Interfaces 2012, 5, 192–198.
(12) Mutai, T.; Satou, H.; Araki, K. Nat. Mater. 2005, 4, 685–687.
(13) Horiuchi, S.; Tokunaga, Y.; Giovannetti, G.; Picozzi, S.; Itoh, H.; Shimano, R.; Kumai,
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R.; Tokura, Y. Nature 2010, 463, 789–792.
5
6
7
(14) Delaire, J. a; Nakatani, K. Chem. Rev. 2000, 100, 1817–1846.
8
9
(15) Lu, H.; Gautier, R.; Donakowski, M. D.; Tran, T. T.; Edwards, B. W.; Nino, J. C.;
Halasyamani, P. S.; Liu, Z.; Poeppelmeier, K. R. J. Am. Chem. Soc. 2013, 135, 11942–
11950.
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(16) Davis, D.; Sreekumar, K.; Sajeev, Y.; Pal, S. J. Phys. Chem. B 2005, 109, 14093–14101.
(17) Badan, J.; Hierle, R.; Perigaud, A.; Zyss, J. In Nonlinear Organic Crystals: Theoretical
Concepts, Materials, and Optical Properties, ACS Symposium Series, 1983; Vol. 233
Chapter 4, pp 81–107.
(18) McCrone, W. C.; Fox, D.; Labes, M. M. In Physics and Chemistry of the Organic Solid
State, New York: Wiley Interscience 1965; Vol 2.
(19) He, Z.; Zhang, L.; Mei, J.; Zhang, T.; Lam, J. W. Y.; Shuai, Z.; Dong, Y. Q.; Tang, B. Z.
Chem. Mater. 2015, 27, 6601–6607.
(20) Zhang, Y.; Song, Q.; Wang, K.; Mao, W.; Cao, F.; Sun, J.; Zhan, L.; Lv, Y.; Ma, Y.; Zou,
B.; others. J. Mater. Chem. C 2015, 3, 3049–3054.
(21) Hariharan, P. S.; Mariyatra, M. B.; Mothi, E. M.; Neels, A.; Rosair, G.; Anthony, S. P.
New J. Chem. 2017, 41, 4592–4598.
(22) Bernstein, J.; Davey, R. J.; Henck, J. O. Angew. Chemie ꢁ Int. Ed. 1999, 38, 3440–3461.
(23) Schulze, M.; Utecht, M.; Hebert, A.; RückꢀBraun, K.; Saalfrank, P.; Tegeder, P. J. Phys.
Chem. Lett. 2015, 6, 505–509.
ACS Paragon Plus Environment
28

Page 29 of 33
Crystal Growth & Design
1
2
3
4
(24) Braga, D.; Cojazzi, G.; Paolucci, D.; Grepioni, F. CrystEngComm 2001, 3, 159ꢀ161.
5
6
7
8
9
(25) Hovhannisyan, V. A.; Su, P.ꢀJ.; Dong, C.ꢀY. In European Conference on Biomedical
Optics; 2011; p 808710.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(26) Priimagi, A.; Ogawa, K.; Virkki, M.; Mamiya, J.; Kauranen, M.; Shishido, A. Adv. Mater.
2012, 24, 6410–6415.
(27) Berkovic, G.; Krongauz, V.; Weiss, V. Chem. Rev. 2000, 100, 1741–1754.
(28) Iliopoulos, K.; Krupka, O.; Gindre, D.; Sallé, M. J. Am. Chem. Soc. 2010, 132, 14343–
14345.
(29) Sergeeva, E. V.; Puntus, L. N.; Kajzar, F.; Rau, I.; Sahraoui, B.; Pekareva, I. S.;
Suponitsky, K. Y.; Bushmarinov, I. S.; Lyssenko, K. A. Opt. Mater. (Amst). 2013, 36, 47–
52.
(30) Skakle, J. M. S.; Low, J. N.; Wardell, J. L.; Glidewell, C. Acta Crystallogr. Sect. B Struct.
Sci. 2005, 61, 321–328.
(31) Chaudhary, A.; Mohammad, A.; Mobin, S. M. Cryst. Growth Des. 2017, 17, 2893–2910.
(32) Huang, S. L.; Hor, T. S. A.; Jin, G. X. Coord. Chem. Rev. 2017, 346, 112–122.
(33) Choudhury, A. R.; Nagarajan, K.; Guru Row, T. N. CrystEngComm 2006, 8, 482ꢀ488.
(34) Zhang, L.; Dang, L.; Luo, F.; Feng, X. J. Mol. Struct. 2016, 1106, 114–120.
(35) Oliver, S. N.; Pantelis, P.; Dunn, P. L. Appl. Phys. Lett. 1990, 56, 307–309.
(36) Reddy, J. P.; Swain, D.; Pedireddi, V. R. Cryst. Growth Des. 2014, 14, 5064–5071.
ACS Paragon Plus Environment
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