8
S. Karthick, A. Santha and D. Ganesh et al. / Journal of Molecular Structure 1224 (2020) 129065
2
(
non-interacting) atoms. It is further suggested that the w(r)
found to be 2.21 GW/ cm . The THz measurements made with this
as grown OH1 single crystals revealed that, it could be a suitable
candidate to realize their THz applications such as homeland secu-
rity, communication, pharmaceutics, medicine and the detection of
chemicals or explosives which exhibit fingerprints in between 0.1
to 3 THz range. The Hirshfeld surface analysis yielded the details
regarding the 3D surfaces and 2D finger print patterns for a single
molecule based on promolecule concept and the bonding contribu-
tions responsible for intermolecular interactions. Thus, by consid-
ering the above factors such as better optical transmission, large
laser damage threshold value, efficient THz generation and surface
analysis, it could be stated that OH1 single crystal could be a suit-
able candidate for THz generation and related applications.
lies between 0 and 1 and that the integration over the product
w(r)ρ(r), the weighted electron density, provides molecular prop-
erties. In this approach every constituent atom contributes to the
molecular electron density depending upon its own charge density
in a way much similar to partners in the stockholders’ corpora-
tion [43]. Later, in 1997, the Hirshfeld partitioning with a surface
(
HS) scheme was suggested by Spackman by defining a molecu-
lar electron density in the weighted region of w(r) ≥ 0.5 (instead
of weighting the electron density of crystal by w(r)) so that the
contribution of promolecule exceeds that from all the neighbour-
ing molecules. This approach provided convenient means of pre-
venting the overlapping with the neighbouring molecules and still
providing maximum proximity amongst them and thereby creat-
ing intermolecular voids [45]. For the present investigation, the
three-dimensional (3D) Hirshfeld surface analysis and the two-
dimensional (2D) intermolecular interactions of the OH1 molecule
were carried out using Crystal Explorer 3.1 software package [46].
The mapping of normalized contact distance (d norm), shape index
and curvedness (shown in Fig. 11a, b & c respectively) have been
performed by feeding its crystallographic data. From the figure it
could be seen that the three characteristic colors such as red, blue
and white appeared in the d norm scheme belongs to the closer
contacts with negative d norm value, longer contacts with positive
d norm value and contacts equal to the Van der Waals separation
Declaration of Competing Interest
None of the authors has any potential financial conflict of inter-
est related to this manuscript.
CRediT authorship contribution statement
S. Karthick: Writing - original draft, Investigation, Conceptu-
alization, Methodology, Software. A. Santha: Investigation, Formal
analysis. D. Ganesh: Investigation, Formal analysis. K. Thirupu-
galmani: Investigation. S. Ganesamoorthy: Methodology, Funding
acquisition. A.K. Chaudhary: Investigation, Funding acquisition. S.
Brahadeeswaran: Writing - review & editing, Supervision, Project
administration, Methodology, Funding acquisition.
(
d norm = 0) respectively. Further, de represents the distance from
the Hirshfeld surface to the nearest nucleus external to the surface
and d is nearest nucleus internal to the surface. The close contacts
i
of the molecules are shown in Fig. 12 along with distances that
Acknowledgements
combine both de and d , each normalised by the van der Walls
i
radius. From the figure, the red–white–blue colouring scheme is
used to distinguish it from the red–green–blue schemes, contacts
shorter than van der Walls separations show up as red spots on
a largely blue surface. The two shorter N- -H—O contacts of each
The authors AS, SG and SB gratefully acknowledge the UGC-
DAE Consortium for Scientific Research for their financial sup-
port through the grant CSR-KN/CRS-112/2018–19/1051 dated 26–
12–2018. The authors AKC, DG gratefully acknowledge the finan-
cial support from the DRDO, Ministry of Defence, Govt. of India,
ACRHEM (Phase –III).
˚
distance 1.981 A were characterized from two red spots, one at the
left of the OH1 molecule and one at the right. The other contact is
˚
associated with C—H- -O of distance 2.472 A. Fig. 13 shows the
2
D Finger print plots of various intermolecular interactions show-
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bonding connections. The remaining contributions were from H••C
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[
In conclusion, the OH1 material was successfully synthesized
in the laboratory and optical quality single crystals were grown
from methanol solvent. The chemical composition of the purified
OH1 was found to be identical with that of theoretically calcu-
lated values. The lattice parameters were analysed using single
crystal X-ray diffraction analyses whereas the crystalline phase of
the OH1wasconfirmed through powder X-ray diffraction analysis.
The functional groups present in the OH1 compound were assigned
through FTIR measurement. Further, higher transmission spectrum
of about 85% was achieved from the polished OH1 single crystal
owing to the purity of the staring material and optical quality of
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