Experimental, quantum chemical studies and Hirshfeld surface analysis on molecular structure of two picrate salts: 1, 4-diaza bicyclo [2,22] octane and Furan-2yl methanamine

Article abstract of DOI:10.1016/j.molstruc.2018.05.069

Two new picrate salts, namely, 1, 4-diaza bicyclo(2,2,2)octanium picrate [DABCOP] and Furan-2yl methanaminium picrate [FMP] has been successfully crystallized by Slow Evaporation Solution growth Technique (SEST). The crystal and molecular structures have been determined by single crystal X-ray diffraction method. The crystal packings of the both the crystals feature classical N–H?O hydrogen bonds and C–H?O interactions. In DABCOP, each diaza molecule is linked to the picric acid which forms cyclic R₄ ⁴(19) and R₄ ⁴(18) motifs. In FMP, most of the ortho related nitro group in anion are involved in N–H?O hydrogen bonding network forming five ring R₁ ²(6), R₂ ¹(4), R₂ ⁴(4), R₁ ²(6), and R₂ ²(5) motifs. Also, a weak C–H?O interaction forming a dimer R₂ ²(8) motif with donor-acceptor distance of 3.413(2) ?. Based on the Hartree-Fock (HF) and Density Functional Theory (DFT) method with 6–311++G (d,p) basis set, the molecular vibrational bands were interpreted. HOMO and LUMO analysis of the molecules were calculated using corresponding methods with the same basis set. In addition, Mulliken charge analysis and thermodynamic properties were calculated. Hirshfeld surface analysis and associated two dimensional fingerprint plots show intermolecular contacts and their relative contribution via colored contour approach.

Full text of DOI:10.1016/j.molstruc.2018.05.069

Accepted Manuscript
Experimental, quantum chemical studies and Hirshfeld surface analysis on molecular
structure of two pictrate salts: 1, 4-diaza bicyclo [2,22] octane and Furan-2yl
methanamine
K. Saminathan, S. Athimoolam, N. Karthikeyan, K. Sivakumar
PII:
S0022-2860(18)30637-9
10.1016/j.molstruc.2018.05.069
MOLSTR 25242
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 8 February 2018
Revised Date: 21 May 2018
Accepted Date: 21 May 2018
Please cite this article as: K. Saminathan, S. Athimoolam, N. Karthikeyan, K. Sivakumar, Experimental,
quantum chemical studies and Hirshfeld surface analysis on molecular structure of two pictrate salts: 1,
4-diaza bicyclo [2,22] octane and Furan-2yl methanamine, Journal of Molecular Structure (2018), doi:
10.1016/j.molstruc.2018.05.069.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Experimental, quantum chemical studies and Hirshfeld surface analysis on molecular structure of two
pictrate salts: 1, 4-diaza bicyclo[2,22] octane and Furan-2yl methanamine
K.Saminathana, S. Athimoolamb, N. Karthikeyanc and K.Sivakumarc
aDepartment of Physics, University V.O.C.College of Engineering, Anna University, Tuticorin, India.
bDepartment of Physics, University College of Engineering Nagercoil, Anna University Nagercoil 629 004, India.
cDepartment of Physics, Anna University, Chennai 600 025, India.
*E-mail: ksaminathan2002@yahoo.com
Graphical Abstract:

ACCEPTED MANUSCRIPT
Experimental, quantum chemical studies and Hirshfeld surface analysis on
molecular structure of two pictrate salts: 1, 4-diaza bicyclo[2,22] octane and
Furan-2yl methanamine
K.Saminathana, S. Athimoolamb, N. Karthikeyanc and K.Sivakumarc
aDepartment of Physics, University V.O.C.College of Engineering, Anna University, Tuticorin,
India.
bDepartment of Physics, University College of Engineering Nagercoil, Anna University
Nagercoil 629 004, India.
cDepartment of Physics, Anna University, Chennai 600 025, India.
*E-mail: ksaminathan2002@yahoo.com
Abstract
Two new picrate salts, namely, 1, 4-diaza bicyclo(2,2,2)octanium picrate [DABCOP] and
Furan-2yl methanaminium picrate [FMP] has been successfully crystallized by Slow Evaporation
Solution growth Technique (SEST). The crystal and molecular structures have been determined
by single crystal X-ray diffraction method. The crystal packings of the both the crystals feature
classical N-H…O hydrogen bonds and C-H...O interactions. In DABCOP, each diaza molecule
4
4
is linked to the picric acid which forms cyclic R4 (19) and R4 (18) motifs. In FMP, most of the
ortho related nitro group in anion are involved in N-H...O hydrogen bonding network forming
2
1
4
2
2
five ring R1 (6), R2 (4), R2 (4), R1 (6), and R2 (5) motifs. Also, a weak C-H...O interaction
2
forming a dimer R2 (8) motif with donor-acceptor distance of 3.413(2) Å. Based on the Hartree-
Fock (HF) and Density Functional Theory (DFT) method with 6-311++G (d,p) basis set, the
molecular vibrational bands were interpreted. HOMO and LUMO analysis of the molecules were
calculated using corresponding methods with the same basis set. In addition, Mulliken charge
analysis and thermodynamic properties were calculated. Hirshfeld surface analysis and
associated two dimensional fingerprint plots show intermolecular contacts and their relative
contribution via colored contour approach

ACCEPTED MANUSCRIPT
Introduction
The growing interest paid to heterocyclic molecules with intermolecular interactions remains a
challenge for researchers around the world and understanding the crystal packing which
mandates the field of crystal engineering [1-6]. Hydrogen bond is a unique feature to exhibit the
properties of molecular crystals. The formation of charge transfer complex depending on the
nature of the donor-acceptor system and the orientation of anionic and cationic species [7,8]. It
facilitates the formation of hydrogen bonds between the cation and anion in the crystalline
assembly. In the present work, two different compounds of picrate salts namely 1, 4-diazabicyclo
(2, 2, 2) octane (DABCO) and Furan-2-yl methanamine (FM) were successfully crystallized and
investigated. Picric acid is used in making explosives and also as an intermediate in dye
manufacturing [9]. As a proton donor, it has the capability of forming stable picrate compounds
with organic molecules due to the presence of active and ionic bonds [10]. The complexes of
picric acid are interesting candidates due to the presence of phenolic OH and electron
withdrawing nitro groups. These groups are acting as hydrogen bond donors and acceptors for
the ions leading to organic salts. Crystals of 1,4-diazabicyclo (2.2.2) octane (DABCO) is widely
used as catalyst [11] and the resemblance of cage like structure exhibit outstanding complex
forming ability, physical and chemical properties [12]. DABCO are used in dye lasers and non-
toxic base catalyst for various organic reactions with high yield [13]. The presence of nitrogen
atoms shows different basic nature, facilitating the formation of monocations [14]. Numerous
crystal structures of salts [15-17] and addition compounds of DABCO, such as adducts with
trimethyl aluminium boron trifluoride and boranes [18] and coordination polymers with metal
ions have been published [19]. Charge-transfer interactions of DABCO with bromine and carbon
tetrabromide resulting in crystalline complexes have also been reported. Furthermore,
cocrystallization phenomena of DABCO with phenols have successfully been employed for the
separation of phenolic natural products by molecular recognition [20-22]. Substituted furan
derivatives are fundamentally important heterocyclic molecules and are present in many natural
and medicinal structures [23,24]. Among various furan derivatives, butenolides have appeared in
the literature as interesting components for the formation of natural and pharmacological
compounds [25]. The synthesis of heterocyclic molecules is in great demand due to its wide
range of biological activities. Many drugs, such as antifungal drugs, nitroimidazole, azomycin
and metronidazole, contain an imidazole ring as its prime importance. It was already reported

ACCEPTED MANUSCRIPT
that the imidazole ring react with picric acid molecule and forms a salt of imidazolium picrate in
acetone, which crystallizes in the orthorhombic system and the structural, optical, mechanical
and vibrational properties of the salt were also been investigated [26-28]. Surprisingly, a new
crystal has been crystallized in triclinic system with centrosymmetric space group. A literature
survey done through Cambridge Structural Database (CSD) and other related scientific works
reveals more work on synthesis point of view of these two molecules whereas there are few work
on materials aspect for its physiochemical properties [29-33].
The two new salts, namely, 1, 4-diazabicyclo (2,2,2) octanium picrate (DABCOP) and
Furan 2-yl methanammonia picrate (FMP) has been reported which predicts the hydrogen
bonding patterns and motifs obtained in the ionic crystals. The structural and electronic
properties of new salts have been studied using Hartree-Fock (HF) and Density Functional
Theory (DFT) methods. The interaction between these molecules provide useful information for
researchers to know the nature of hydrogen bonding interactions. The optimized structure and
vibrational frequencies are done using the same quantum chemical methods. Further,
experimental IR spectral analyses were also done for the two salts and compared with its
theoretical counterparts. The HOMO-LUMO energies were also been computed with other
thermodynamic parameters by the same methods.
Experimental
1,4–Diazabicyclo[2.2.2]octane (0.112g, 0.001M) was dissolved in distilled ethanol and
transferred slowly in drops to the ethanolic solution of picric acid (0.229g, 0.001M). After
continuous stirring for about 1 hr, a homogeneous yellow colour solution was the final stage and
the solution was kept for crystallization at room temperature under atmospheric condition by
slow evaporation method. Yellow coloured, needle shaped crystals were obtained in one week.
Ethanolic solution of Furan-2-yl-methanamine (0.1018g, 0.001M) was added drop wise to picric
acid (0.229g, 0.001M) ethanol solution with an effective stirring. The final solution was kept for
crystallization under atmospheric condition free from any disturbance. Red coloured, prismatic
shaped crystals were obtained by the slow evaporation. X-ray intensity data of the grown crystals
were collected at room temperature with MoKα radiation (λ=0.71073 Å) using Bruker AXS
KAPPA APEX-2 diffractometer equipped with graphite monochromator. The structure was
solved by direct methods and refined by full-matrix least-squares calculations using

ACCEPTED MANUSCRIPT
SHELXL2014 software [34]. The FTIR spectra of the grown crystals were recorded in the KBr
phase in the frequency region of 4000–400 cm-1 using a Jasco Spectrometer, model 410 under a
resolution of 4 cm-1 with a scanning speed of 2mm/sec.
Computational details
Theoretical calculations were carried out using Gaussian 09 [35] software package. The
geometry optimization and vibrational modes calculation of DABCOP and FMP were carried out
with both Density Functional Theory (DFT) and Hartree–Fock (HF) methods, which gives the
structural and spectral characteristics. The starting geometry for both the salts were taken from
single crystal X-ray studies and optimized using DFT employing the Becke-3–Lee–Yang–Parr
(B3LYP) and HF methods supplemented with the standard 6-311++G(d,p) basis set. The
electronic properties of the compounds have been computed, which determines the way a
molecule interacts with other species [36]. HOMO-LUMO for both DABCOP and FMP were
performed. Both the compounds were compared to analyze the charge interaction and activity of
the compound. The thermodynamic parameters for both the salts were also calculated by HF and
DFT methods.
Results and Discussion
Molecular Geometry
The molecular structures of the compounds, DABCOP and FMP, with atom labeling were shown
ꢀ
in Fig.1 (a-b) which crystallizes in P21/n and P1 space group respectively. The unit cell
parameters and crystallographic data are shown in Table 1. The selected geometric parameters
(bond length, bond angle and torsion angle) are shown in Table S1, S2 and S3 which are slightly
deviated from the experimental values. In FMP, there occurs disorder of the picric acid in the
ortho-NO2 group and the structure description is based on the major orientation of the disordered
picric acid. Normally, in picric acid the C-C bond distance varies from 1.36 to 1.40 Å. However,
the elongation in the C-C bond distance of picric acid confirms the presence of inter-molecular
interaction in both the compounds. The experimental C-C bond distance varies from the
theoretical values by 0.01 to 0.03 Å. The C-N bond distance agrees well with the experimental
value. The two oxygen atoms O1 and O3 bridge the neighbouring diaza compound (DABCOP),
where as O1 atom do the same in furan compound (FMP). The bond angles of picrate anion
confirm the deprotonation of phenolic group and the geometry is similar to other picrate

ACCEPTED MANUSCRIPT
complexes [37]. Also, the phenolic proton transfer of anion to DABCO and FM is confirmed by
the C11-O1 bond distance. The diaza cation C-N bond distances are elongated compared to a
similar feature observed by Ferguson et al. [38, 39]. In both the cations, the C-N bond involving
the protonated N atoms are elongated than the non-protonated N atoms. The nitro groups in
DABCOPꢀ are slightly twisted around their C-N bond distances. The N-H bond distance is
stronger in diaza cation than furan cation which confirms that there exhibits stronger N-H…O
intermolecular interactions that stabilize the crystal structure. All the bond distances and bond
angles for both the compound are slightly deviated from the theoretical value. The difference is
due to the fact that in experimental measurement the molecules are in condensed phase and in
theoretical measurement the molecules are in gaseous phase.
The ortho nitro group of picrate anion is twisted from the plane of the ring while the para
nitro nitro group is nearly co-planar. The angle between the rings of picrate anion and the FMP /
DABCOP cation are 24.2(1) / 20.3(1)°, respectively. In DABCOP compound, the back bone
conformation angles of cation ψ1 (C27-N20-C24-C21, C33-N20-C24-C21) and ψ2 (C14-C15-
C16-N8) are cis- and trans-oriented respectively. The side-chain conformation of anion in
DABCOP χ1 (O3-N2-C12-C11) is 13.7° and the calculated values by HF/DFT are -26.887°/-
25.182° respectively. There is a disorder in picrate anion when crystallize with furan-2yl
methanamine. In FMP compound, the back bone conformation angles of picrate anion ψ1(O10-
N8-C16-C11) and ψ2(C12-C13-C14-N5) are cis- and trans- oriented respectively. In solid
crystalline state, the side-chain conformation angles of anion and cation χ1 (O3-N2-C12-C11,
O9-N8-C16-C15) and χ2 (N30-C26-C25-C23, N30-C26-C25-O29) are -28.1°, 48.5°,-92.8°, 89.2°
respectively whereas they differ from the calculated values. In the anion and cation, the
formation of charge transfer complex depends on the nature of the donor-acceptor system and the
orientation of anionic and cationic species which facilitates the formation of expected N–H···O
hydrogen bonds between amino hydrogen and phenolic oxygen. The protonation on the N site of
the cation is confirmed from C-N bond distances and C–N–C bond angles.
.
Hydrogen bonding features
The intermolecular and intramolecular hydrogen bonds usually involve a hydrogen atom that
normally bound to an electronegative atom such as N, O and interacts by electrostatic forces to
another electronegative atom and this kind of interactions can enhance the packing arrangement

ACCEPTED MANUSCRIPT
and stability of crystal. It is also responsible for large modifications of the nonlinear
polarizabilities [40]. The crystal structure of DABCOP and FMP displays a three dimensional
hydrogen bonding network shown in Table 2 and 3. Different crystal packing is observed in
DABCOP and FMP compound (Fig.2 (a-b)). In FMP, most of the ortho related nitro group of
picrate are involved in the N-H...O hydrogen bonding interactions thereby forming five ring
2
1
4
2
2
R1 (6), R2 (4), R2 (4), R1 (6), and R2 (5) motifs. Also, a weaker C-H...O interaction is formed
2
with H atom in the cation forming a dimer R2 (8) motif with donor-acceptor distances of 3.41 Å.
From Fig.3a, when viewed along a axis, the face to face molecules [41], anion-anion and cation-
cation, is almost parallel with a dihedral angle of 2.8 and 2.2° respectively. But in DABCOP
when viewed along a axis no face to face molecule is observed (Fig.3b). The two bifurcated ring
2
R1 (6) motifs are formed by same phenol H atom but different ortho nitro group of picric acid.
4
The ring R2 (4) motif is formed by the same N-H..O hydrogen bond formed between the H atom
of the amine group in furan compound and O atom in nitro group of anion. The crystal packing
of FMP consists of dimer and ring as shown in Fig. 2 (a) with a sheet like structure when viewed
along crystallographic c axis and they form an infinite one-dimensional chain and are separated
by a distance of 6.84 Å. The ortho nitro group of picric acid and side-amine chain of furan
compound are twisted from the plane of the ring of about 0.73 and 1.03 respectively. But in
DABCOP, the nitro group of picric acid is twisted from the plane of the ring of about 0.97 Å.
Hence, the anion is slightly twisted in FMP than DABCOP compound. The disorder in the nitro
group of anion affects the chain formation and packing arrangement of the atoms. In the
asymmetric unit (Fig.1 (b)), the diaza and picrate ions are linked by the intermolecular N–H…O
hydrogen bond and C-H…O, C-H…N intermolecular interactions, where the cation acts as a
hydrogen donor in this bifurcated system. Each diaza molecule is linked to the picric acid which
4
4
forms cyclic R4 (19) and R4 (18) motifs (Fig.2 (b)) which are packed into molecular ribbons [
42] forms corrugated layer structure parallel to each other in ( 0 ) and (2 0 2) planes and are
separated by a distance of 9.37 Å. The adjacent cyclic motifs are bridged by C-H…N interaction
(Fig. 2 (b)). From the result, it is clear that four N-H…O hydrogen bonding network with the
donor-acceptor distances of about 2.73, 2.93, 2.83 and 2.96 Å respectively stabilizes the FMP
crystal structure where in DABCOP crystal structure is stabilized by a single N-H…O hydrogen
formed the phenol H atom of the anion. Fig. 4 shows the showing (a) face to face molecule in
FMP (b) no face to face molecule when viewed along a axis

ACCEPTED MANUSCRIPT
Mulliken Population Analysis
The total atomic charges of DABCOP and FMP obtained by Mulliken population analysis with
HF and DFT by 6-311++G (d,p) basis set are listed in Table. 4, 5 and as a bar diagram in Fig 5.
From the result, it is clear that the substitution of proton in the N atom of both the compound
have redistributed the electron density over the molecule. In FMP, the N8 atom is positive in
DFT whereas negative in HF this is due to the high electronegative character of O atom in DFT
whereas in DABCOP, N20 atom is positive may be due to the formation of C-H…N interaction.
Among the carbon atoms, C23 is more positive charged. The C25 atom is connected to highly
electro negativity atom O29, hence the adjacent atom C23 loses electrons and this is reason for
the high positive nature. In DABCOP, the carbon atoms C11 and C12 are highly positive may be
they losses their electrons to N atom that take part in N-H…O hydrogen bonding. Carbon atoms
have both positive and negative charges, which show that carbon atoms are highly influenced by
their substituent. All the H atoms in anion as well as in cation are positive as they lose their
electrons to the nearby carbon atoms. The presence of large negative charge on O and N atom
and net positive charge on H atom may suggest the formation of intermolecular interaction in
solid forms [43]. When magnitudes of the charge of each atom predicted by the two methods are
compared, the magnitude predicted by B3LYP is relevant than predicted by HF method even
though the basis set is same.
FT-IR spectral analysis
The FT-IR spectrum and theoretical IR spectra of the title compounds are shown in Fig.6a,6b.
The bands are calculated in the measured region 4000-450cm-1 and the assignments of some
important bands are given in Table 6 and 7. The formation of complex salts of picrate is strongly
evident by the presence of characteristic infrared bands of the donor and acceptor in the spectrum
of DABCOP and FMP salt with slight changes in frequencies. The differences between the
experimental and theoretical vibrational modes are observed. This discrepancy may be due to the
formation of intermolecular hydrogen bonding. Also some vibrations identified in the solid phase
experimental spectra could not be identified in the simulated counterpart and therefore, have
been omitted. The differences between calculated and experimental frequencies are due to
anharmonicity, intermolecular interaction, an approximation treatment of electron correlation
effects and the limited basis sets [44].

ACCEPTED MANUSCRIPT
N-H vibrations
Normally the N-H stretching vibrations occur in the region of 3500-3000 cm-1[45]. In FMP, the calculated
N-H symmetric stretching vibrations by HF / DFT methods are 3694 /3476respectively, and
experimentally a strong band is observed at 3435 cm-1. The calculated N-H asymmetric stretching
vibrations by HF / DFT methods are 3761/3537 respectively. Both the N-H symmetric and asymmetric
stretching vibrations occur in the imidazole ring where the intermolecular interactions take place. The N-
H in-plane bending is observed as a strong band at 1561 cm-1 and calculated at 1723/ 1574 cm-1
by HF/DFT methods respectively. There is a overlapping of N-H, C-H and C-N in-plane bending
vibrations which are calculated by HF/DFT methods. In DABCOP, the N-H stretching vibration is
observed in the region 1557 cm-1 and the calculated vibrations by HF/DFT methods are 1721 /1554 cm-1 .
The scissoring vibration is predicted in HF/DFT method and experimentally it has been observed as a
weak band in the region 2066 cm-1
.
C-H, C-N, C=C and C=O vibrations
The C-H stretching vibrations are expected to occur in the region 3000-3100 cm-1 [46].
Generally this region is not affected by the nature of the substituent. But in FMP and DABCOP,
the calculated values of C-H stretching vibration by HF/DFT methods differ by ~300/~100 cm-1
respectively. The deviation may due to the formation C-H…O intermolecular interaction in both
the compound which connects the cation and anion. In FMP, in imidazole ring the C-H
symmetric stretching vibrations is observed as a strong band at 3086 cm-1 and the calculated
values by HF/DFT methods are 3236/3076 cm-1 respectively. The C-H asymmetric stretching
vibrations calculated by HF/DFT methods occur in the region 3314/3145 cm-1, 3410/3245 cm-1
respectively. In DABCOP, the C-H symmetric stretching vibrations are observed as strong band
at 2962 cm-1 and 3087 cm-1. In the theoretical calculations the HF values are more deviated from
DFT values which may be due to the delocalization of electron in the aromatic ring.
In pyrimidine, the C-N and C=C stretching vibrations occur in the region 1600-1500 cm-
1. In FMP the C-N in-plane bending vibration is not observed experimentally but the calculated
values by HF/DFT methods are 1784/1628 cm-1 respectively. The C=C stretching vibrations are
calculated by HF/DFT methods are 1680, 1686/1513, 1527 cm-1 respectively. The C=O
stretching vibrations are expected to occur in the region 1710-1712 cm-1 as strong band. The
carbonyl absorption in DFT/HF at 1707/1834 cm-1 confirms the COO-groups of the compound. In FMP,
the C=O stretching band calculated by HF/DFT are1723/1574 cm-1 respectively. The presence of this

ACCEPTED MANUSCRIPT
band confirms the formation of picrate salts of DABCOP and FMP. The assignment is in very close
agreement with data of the complex salts reported already [47, 48].
N-H...O hydrogen bond interaction
The N-H...O stretching vibration has been expected to occur in the region 3000-3500 cm-1. In the
present picrate salt of FMP/DABCOP, the N-H...O vibrations occur as a strong band in the
region 3086 /2962cm-1 respectively. The HF value agrees well with the experimental value but in
DFT the downshift may be due to the increase in N-H bond distance.
Thermodynamic properties
The thermodynamic properties of materials are closely related to their vibrational properties,
yielding not only a guidance for insights about their atomic lattice behavior, but also providing
essential information for technological applications [49]. The values of some thermodynamic
parameters (such as thermal energy, heat capacity, entropy, zero-point vibrational energies
(ZPVE), rotational constants and dipole moment) of the title compound calculated at HF and
B3LYP/6-311++G(d, p) levels without experimental determination are shown in table 8. Dipole
moment reflects the molecular charge distribution and is given as a vector in three dimensions. It
is used to depict the charge movement across the molecule and strictly obeys for a neutral
molecule which depends on positive and negative charges. From table 8, the ZPE for
FMP/DABCOP was obtained to be 156.419, 143.624 K cal mol-1 and /201.897, 186.413 K cal
mol-1 respectively. The entropy for both the compounds is quite significant. The results of the
energies, dipole moment, entropy, and ZPE can be used to the new synthesis of some hydrazine -
hydrazones compounds [50].
Frontier Molecular Orbitals
Energies of HOMO and LUMO are popular quantum mechanical descriptors. It has been
shown that these orbital play a major role in governing many chemical reactions, and are also
responsible for charge transfer complexes [51].The frontier orbital (HOMO and LUMO) of the
chemical species are very important in defining its reactivity [52]. The difference in energy
values are tabulated in Table. 9 and are shown in Fig. S1 (a-b). The value of the energy
separation between the HOMO and LUMO was found as 8.704/3.889 eV (HF/DFT) for FMP and
8.432/3.753 eV (HF/DFT) for DABCOP. This large energy gap indicates that FMP is quite
stable. Lower value in the HOMO and LUMO energy gap explains the eventual charge transfer
interactions taking place within the molecule. The larger the HOMO-LUMO orbital energy gap,

ACCEPTED MANUSCRIPT
the harder the molecule. The hardness has been associated with the stability of the chemical
system [53]. In the present work, the DABCOP compound is found to softer molecule and they
are highly polarizable than FMP compound. The energy gap between HOMO and LUMO has
been used to prove the bioactivity from intermolecular charge transfer [54-57].
Hirshfeld surface analysis
Hirshfeld surface analysis is a novel tool for the graphical representation of intermolecular
contacts in the crystal environment via colored contouring approach. It’s associated two
dimensional fingerprint plots provide information about the unique distribution of closer contacts
involved in the molecular structure [58-62]. Hirshfeld surface analysis and their associated two
dimensional fingerprint plots of the title compounds were mapped using Crystal Explorer
V3.1software [63]. The Hirshfeld surfaces of the compounds FMP and DABCOP is shown in
Fig. 7 and the surfaces were mapped over the dnorm range of -0.674 to 1.326 (FMP) and -0.689 to
1.292 (DABCOP). In the compound FMP the surfaces are dominantly highlighted by N-H…O
hydrogen bond interactions through O…H contact, which are clearly exhibited by dark red color
regions in the Hirshfeld surface. The ortho related nitro group in the anion is involved in
bifurcation of hydrogen bonding with adjacent hydrogen atoms of the amine (NH) group was
also evident from the analysis [64-65]. The light red regions on the Hirshfeld surface features to
C-H…O weak hydrogen bonding interactions. Consequently in the compound 2, the Hirshfeld
surfaces are mainly covered by strong N-H…O (bifurcated) hydrogen bonding interactions.
Further the 2D fingerprint plots retrieved from the Hirshfeld surfaces of the compounds FMP and
DABCOP is shown in Fig. S2. As discussed above the 2D fingerprint plots reveals the majority
proportion of interactions are due to O…H contacts (~ 55%) involved in the strong and weak N-
H…O and C-H…O hydrogen bonding interactions in both the compounds. The other highest
contribution is made with H…H contacts (~ 25%) due to substituent groups. In addition
relatively weak contacts such as O…C, O…O, C…H and H…C are also observed. The overall
proportion of all the contacts involved in the compounds FMP and DABCOP is shown via pie
chart (Fig. 8).
Conclusion
The present work of FMP and DABCOP has been thoroughly analyzed by theoretical and
experimental X-ray studies. The optimized geometrical parameters have been calculated at

ACCEPTED MANUSCRIPT
B3LYP/6-311++G (d,p) basis set using HF/DFT method, which shows a slight variation from
experimental values. Crystal packing of the title compound is formed by intermolecular
interactions. The donor-acceptor distance agrees well making stronger N-H…O intermolecular
hydrogen bonding that stabilizes the crystal structure. Mulliken population analysis gives a clear
knowledge that the substitution of proton form the anion, both the compound has redistributed
the electron density over the molecule. The shifting of vibrational bands as well as theoretical
peaks of the infrared (IR) due to the intermolecular hydrogen bonds was also analyzed and
assigned. The thermodynamic properties of both the compound were calculated. HOMO-LUMO
energy gaps explain the charge transfer interactions taking place within the molecule. The
occurrence of closer molecular in the crystal packing of FMP and DABCOP was visualized via
Hirshfeld surface and fingerprint plot analyses.
Supplementary information:
Crystallographic data of the structure reported in this article have been deposited in
the Cambridge Crystallographic data centre. The deposition numbers are CCDC-1508506
(DABCOP) and CCDC-1508507 (FMP). Copy of the data can be downloaded at free charge
from CCDC website (www.ccdc.cam.ac.uk).

ACCEPTED MANUSCRIPT
References
1. S. K. Seth, I. Saha, C. Estarellas, A. Frontera, T. Kar, and S. Mukhopadhyay,
Supramolecular Self-Assembly of M-IDA Complexes Involving Lone-Pair···π
Interactions: Crystal Structures, Hirshfeld Surface Analysis, and DFT Calculations
[H2IDA = iminodiacetic acid, M = Cu(II), Ni(II)], Cryst. Growth & Des. 11 (2017)
3250–3265
2. P. Manna, S. K. Seth, A. Das, J. Hemming, R. Prendergast, M. Helliwell, S. R.
Choudhury, A. Fronter and S. Mukhopadhyay, Anion Induced Formation of
Supramolecular Associations Involving Lone Pair-π and Anion-π Interactions in Co(II)
Malonate Complexes: Experimental Observations, Hirshfeld Surface Analyses and
DFT Studies, Inorganic Chemistry 21 (2012) 3557–3571
3. S. K. Seth, P. Manna, N. J. Singh, M. Mitra, A. D. Jana, A. Das, S. R. Choudhury,
T. Kar, S. Mukhopadhyay and K. S. Kim, Molecular architecture using novel types of
non-covalent π-interactions involving aromatic neutrals, aromatic cations and π-anions,
Cryst. Eng. Comm. 15 (2013) 1285-1288
4. P. Manna, S. K. Seth, M. Mitra, A. Das, N. J. Singh, S. R. Choudhury, T. Kar and
S. Mukhopadhyay,
A
successive layer-by-layer assembly of supramolecular
frameworks driven by a novel type of face-to-face π+–π+ interactions, Cryst. Eng.
Comm. 15 (2013) 7879-7886
5. P. Manna, S. K. Seth, M. Mitra, S. R. Choudhury, A. Bauzá, A. Frontera and S.
Mukhopadhyay, Experimental and computational study of counterintuitive ClO4–···
ClO4–interactions and the interplay between π+–π and Anion··· π+ interactions, Cryst.
Growth & Des. 14 (2014) 5812–5821
6. K.M. Priyadharshini, A. Chandramohan, T.U. Devi, Synthesis, Growth, Crystal
Structure and Characterization of the o-Toluidinium Picrate. J. crystallisation Process
and Technology, 3 (2013)123-129.

ACCEPTED MANUSCRIPT
7. A. C. Cunha, V. F. Ferreira, A. K. Jordão, M. C. B. V. de Souza, S. M. S. V.
Wardell, J. L. Wardell, P. A. Tan, R. P. A. Bettens, S. K. Sethe and E. R. T.
Tiekink, Aryl-substituents moderate the nature of hydrogen bonds, N–H…N versus N–
H…O, leading to supramolecular chains in the crystal structures of N-arylamino 1,2,3-
triazole esters, Cryst. Eng. Comm. 15 (2013) 4917-4929
8. S. K. Seth, V. S. Lee, J. Yana, S. M. Zain, A. C. Cunha, V. F. Ferreira, A. K. Jordão, M.
C. B. V. Souza, S. M. S. V. Wardell, J. L. Wardell and E. R. T. Tiekink, Crystallographic
and computational study of 1-(arylamino)-1,2,3-triazole-4-carbohydrazides, Cryst. Eng.
Comm. 17 (2015) 2255-2266
9. W.Q. Wang, catena-Poly[[[diaqua(1,3-benzimidazole-κN3)manganese(II)]-ꢁ-benzene-
1,3-dicarboxylato-κ3O1,O1′:O3] dihydrate], Acta crystallogr. Sect. E 67 (2011) 4
10. G. Baghavannarayana, B. Riscob, M. Shakir, Growth and characterization of l-leucine
l-leucinium picrate single crystal: a new nonlinear optical material, Materials and
Physics 126 (2011) 20-23
11. G. Laus, V. Kahlerberg, K. Wurst, T. Lorting and H. Schottenberg,10 (2008)1638-1644
12. M.P. Marzocchi, G. Sbrana and G. Zerbi, Structure and Fundamental Vibrations of
Cage Molecules. I. 1,4-Diazabicyclo[2.2.2]octane, J. American chemical Society, 87:7
(1965) 1429-1432
13. B. Baghernejad, 1,4-Diazabicyclo[2.2.2]octane (DABCO) as a useful catalyst in
organic synthesis, European J. Chemistry 1 (1) (2010) 54-60
14. D. Sathya, R. Jagan, R. Padmavathy, R. Mohan Kumar and K. Sivakumar, N—H…O,
O—H…O hydrogen bonded supramolecular sheet formation in the bis(2-
aminoanilium) fumarate, 3-methylanilinium hydrogen fumarate and 4-chloroanilinium
hydrogen fumarate salts, Acta Cryst. C69 (2013) 1-6
15. T.C. Lewis and D.A. Tocher, A low-temperature determination of triethylenediaminium
dichloride dihydrate, Acta Crystallogr.,Sect. E: Struct. Rep. Online, 61(2005) o2202–
o2204

ACCEPTED MANUSCRIPT
16. S.W. Kennedy, P.K. Schultz, P.G. Slade and E.R.T. Tiekink, Triethylenediamine
dihydrochloride, Z. Kristallogr., 180 (1987) 211-217
17. A. Katrusiak, M. Ratajczak-Sitarz and E. Grech, Stereochemistry and transformations
of NH:N hydrogen bonds Part II. Proton stability in the monosalts of 1,4-
diazabicyclo[2.2.2]octane, J. Mol. Struct., 474 (1999) 135-141
18. A. M. Bradford, D. C. Bradley, M. B. Hursthouse and M. Motevalli, Interactions of
1,4-diazabicyclo[2.2.2]octane with Group III metal trimethyls: structures of
Me3M.cntdot.N(C2H4)3N.cntdot.MMe3 (M = aluminum, gallium), Organometallics,
11 (1992) 111-115
19. B.
Singaram
and
G.
G.
Pai,
Addition-Compounds of Boron-
Trifluoride, Boranes and alane withN,N,N',N'Tetramethylethylenediamine And Triethy
lenediamine, Heterocycles, 18 (1982) 387-396
20. X. Wang, H. Sun, X. Sun and X. You, Me2Cd(dabco), Acta Crystallogr., Sect. C:
Cryst. Struct. Commun., C51(1995) 1754-1756
21. A. B. Wiles and R. D. Pike, Copper(I) Chloride Carbonyl Polymers, Organometallics,
25 (2006) 3282-3285
22. A. D. Bond and C. J. McKenzie, One-dimensional zinc-based coordination polymers
incorporating cyanate anions, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 61
(2005) 519-522
23. S. Miao, R.J. Andersen, Rubrolides A-H, metabolites of the colonial tunicate Ritterella
rubra, J. Org. Chem. 56 (1991) 6275-6280
24. M. Kotora, E. Negishi, Highly Efficient and Selective Procedures for the Synthesis of
Alkylidenebutenolides via Palladium-Catalyzed Ene-Yne Coupling of and Palladium-
or Silver-Catalyzed Lactonization of (Z)-2-Ene-4-ynoic Acids. Synthesis of
Rubrolides, Synthesis (1997) 121-128
25. M. Kangani, N. Hazari, M.T. Maghsoodlou, Synthesis of pyrrole and furan derivatives
in the presence of lactic acid as a catalyst, J. Saudhi Chemical society 21 (2017) 160-
164

ACCEPTED MANUSCRIPT
26. C. Sridevi, G. Velraj, Investigation of molecular structure, vibrational, electronic, NMR
and NBO analysis of 5-chloro-1-methyl-4-nitro-1H-imidazole (CMNI) using ab initio
HF and DFT calculations, J. Mol. Struct., 1019 (2012) 50-60
27. A. R. Katritzky, C. W. Rees, Comprehensive Heterocyclic Chemistry, oxford:
pergamon 5 (1984) 469
28. J. Jayabharathi, V. Thanikachalam, N. Srinivasan, K. Jayamoorthy, Physicochemical
studies of bioactive heterocycles of some novel imidazole derivatives as sensitive NLO
materials, Spectrochim. Acta A, 83(2011) 329-336
29. M. Mroueh, C. Daher, E. Hariri, S. Demirdjian, S.Isber, E. S. Choi, B. Mirtamizdoust,
H.H. Hammud, Magnetic property, DFT calculation, and biological activity of bis[(ꢁ2-
chloro)chloro(1,10-phenanthroline)copper(II)]
Interactions 231 (2015) 53-60
complex,
Chemico-Biological
30. B. Mirtamizdoust, M. Ghaedi, Y. Hanifehpour, J.T. Mague, S. WooJoo,
Synthesis, structural characterization, thermal analysis, and DFT calculation of a novel
zinc (II)-trifluoro-β-diketonate 3D supramolecular nano organic-inorganic compound
with 1,3,5-triazine derivative, Materials Chemistry and Physics 182 (2016) 101-109
31. Y. A. Tyula, A. Zabardasti, H. Goudarziafshar, B. Mirtamizdoust, A new hemidirected
lead(II) complex extended in holodirected one-dimensional polymer by secondary Pb–
O interactions: A precursor for preparation of PbO nanoparticles, and DFT study,
Journal of Mol. Struct. 1149 (2017) 142-148
32. B. Mirtamizdoust, M.
Ghaedi, F. Taghizadeh, R. Safari, A. Bazrafshan,
Stereochemically active lone pair on lead(II) nano 3D supramolecular network: Synthesis,
structural characterization, thermal stability and DFT calculation of [Pb(p-2-minh)2],Main
Group Chemistry 15 (2016) 197-208
33. Mirtamizdoust, Babaka, Roodsari, Majid Sadeghib, Shaabani, Behrouzb, Dusek,
Michalc, Fejfarova, Karla, Synthesis, crystal structure and DFT calculations of a new
Hg (II) metal-organic polymer, Main Group Chemistry 15, (2016) 257-266
34. G.M. Sheldrick, Crystal structure refinement with SHELXL, ActaCryst. C71 (2015) 3-8

ACCEPTED MANUSCRIPT
35. M.J. Frisch, G.W. Trucks, H.B. Schlegal, G.E. Scuseria, M.A. Robb, J.R. Cheesman,
V.G. Zakrzewski, J.A. Montgomerg Jr., R.E. Stratmann, J.C. Burant, S. Dapprich,J.M.
Millam, A.D. Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V.Barone, M.
Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J.Ochterski, G.A.
Petersson, P.Y. Ayala, Q. Cui, K. Morokuma, N.Rega, P.Salvador, J.J.Dannenberg,
D.K.Malich, A.D.Rabuck, K.Raghavachari, J.B. Foresman, J Cioslowski, J.V. Ortiz,
A.G. Baboul, B.B. Stetanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.
Gomperts, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A.
Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W.Wong, J.L.
Andres, C. Gonzalez, M. Head-Gordon, E.S. Replogle, J.A. Pople, GAUSSIAN 09,
Revision A 11.4, Gaussian Inc., Pittsburgh, PA, 2009
36. R. Srivastava, L. Sinha, M. Karabacak, O. Prasad, S.K. Pathak, A.M. Asiri, M. Cinar
Spectral features, electric properties, NBO analysis and reactivity descriptors of 2-(2-
Benzothiazolylthio)-Ethanol: Combined experimental and DFT studies, Spectrochim
Acta A:Molecular and Biomoleuclar Spectroscopy 136(2015) 1205-1215
37. K. Anitha, S. Athimoolam and S. Natarajan, L-prolinium picrate and 2-
methylpyridinium picrate, Acta CrystC62 (2006) o567-o570
38. G. Ferguson, W. Bell, P.I. Coupar, & C. Glidewell, Crystal Engineering Using
Trisphenols. Three-Dimensional Hydrogen-Bonding Networks in 1,1,1-Tris(4-
hydroxyphenyl)ethane, its Hydrated Adduct with 1,4-Diazabicyclo[2.2.2]octane (1/1/1)
and its Adduct with Piperazine (4/3). Acta Cryst. B53 (1997) 534-543
39. G. Ferguson, C. Glidewell, R.M. Gregson & P.R. Meehan, Acta Cryst. B54 (1998)
129-138
40. A. Chandramohan et al, The Experiment, Synthesis, Growth, Crystal Structure And
Characterization Of An Organic Salt Single Crystal: Diimidazolium Dipicrate
Monohydrate International Journal of Science and Technology, Vol.25 (4) (2014)1759-
1774
41. P.Y. Chen, L. Zhang, S.G. Zhu and G.B. Cheng, A Comparative Theoretical Study of
Picric Acid and Its Cocrystals, Crystals 5(2015) 346-354

ACCEPTED MANUSCRIPT
42. G. Laus, V. Kahlenberg, K. Wurst, M. Hummel and H. Schottenberger, Crystal
Structure of 2-Ethylimidazole-1-sulfonyl Azide: A New Azidation Reagent, Crystals
2(1) (2012)118-126
43. L.X. Hong, L.X. Ru, Z.X. Zhou, Calculation of vibrational spectroscopic and NMR
parameters of 2-Dicyanovinyl-5-(4-N,N-dimethylaminophenyl) thiophene by ab initio
HF and density functional methods, Computational and Theoretical Chemistry, 969
(2011) 27-34
44. S. Rajeev, D. Kumar, S. Bhoop, V.K. Singh and S. Ranajana , Molecular structure,
vibrational spectroscopic and HOMO, LUMO studies of S-2-picolyl-β-N-(2-
acetylpyrrole) dithiocarbazate Schiff base by Quantum Chemical investigations,
Research Journal of Chemical Sciences, Vol. 3(2) (2013) 79-84
45. R. Anitha, S.Athimoolam, M.Gunasekaran, K. Anitha, X-ray, vibrational spectra and
quantum chemical studies on a new semiorganic crystal: 4-Chloroanilinium
perchlorate, Journal of Molecular Structure, 1076 (2014) 115–125
46. G. Socrates, Infrared and Raman Characteristic Group Frequencies, third ed., Wiley,
New York, 2001
47. K.M. Priyadharshini, A. Chandramohan,T. Uma devi, S. Selvanayagam, and B.
Sridhar, Synthesis, Crystal Growth, Structure, Spectral, Optical and Thermal
Characterization of M-Toluidinium Picrate Single Crystal, International Journal of
ChemTech Research, 5(6) (2013) 2678-2689
48. K.M. Priyadharshini, A. Chandramohan, T. Uma devi, Synthesis, Growth, Crystal
Structure and Characterization of the o-Toluidinium Picrate, Journal of Crystallization
Process and Technology, 3(2013) 123-129
49. E. Moreira, C.A.Barboza, E.L. Albuquerque, U.L.Fulco , J.M.Henriques , A.I.Araújo,
Vibrational and thermodynamic properties of orthorhombic CaSnO3 from DFT and
DFPT calculations, Journal of Physics and Chemistry of Solids, 77(2015) 85–91
50. N. Dege, N. Senyuz, H.Bati, N. Gunay, D. Avci, O. Tamer, Y. Atalay, The synthesis,
characterization
and
theoretical
study
on
nicotinic
acid
[1-(2,3-
dihydroxyphenyl)methylidene]hydrazide, Spectrochim Acta Part A: Molecular and
Biomolecular Spectroscopy, 120 (2014) 323–331

ACCEPTED MANUSCRIPT
51. Fleming, I. Frontier Orbital and Organic Chemical Reactions, John Wiley & Sons,
NewYork 1976
52. N.O. Obi-Egbedi, I.B. Obot, M.I. El-Khaiary, Quantum chemical investigation and
statistical analysis of the relationship between corrosion inhibition efficiency and
molecular structure of xanthene and its derivatives on mild steel in sulphuric acid,
Journal of Molecular Structure, 1002 (2011) 86–96
53. Fukui K., Yonezaw T., Shingu; A Molecualr Orbital Theory of Reactivity in Aromatic
Hydrocarbons, The Journal of Chemical Physics, 20 (1952)722.
54. S. K. Seth, N. C. Saha, S. Ghosh and T. Kar, Structural elucidation and electronic
properties of two pyrazole derivatives: A combined X-ray, Hirshfeld surface analyses
and quantum mechanical study, Chemical Physics Letters, 506 (2011) 309-314
55. S. K. Seth, G. C. Maity and T. Kar, Structural elucidation, Hirshfeld surface analysis
and quantum mechanical study of para-nitro benzylidene methyl arjunolate, Journal of
Molecular Structure, 1000 (2011) 120-126
56. S. K. Seth, S. Banerjee, T. Kar, Crystal structure and DFT calculations of
andrographiside J. Mol. Struct. 965 (2010) 45-49
57. M. Arivazhagan and J. Senthil Kumar, Vibrational assignment, HOMO–LUMO, first-
hyperpolarizability and Mulliken’s charge analysis of 2, 7-dinitrofluorene, Indian
Journal of Pure & Applied physics, 50 (2012) 363-373
58. M. A. Spackman and J. J. McKinnon, Fingerprinting intermolecular interactions in
molecular crystals, Cryst. Eng. Comm, 4 (2002) 378–392
59. S. K. Seth, Tuning the formation of MOFs by pH influence: X-ray structural variations
and Hirshfeld surface analyses of 2-amino-5-nitropyridine with cadmium chloride,
Cryst.Eng.Comm, 15(2013) 1772-1781
60. M. Mitra, P. Manna, A. Bauzá, P. Ballester, S. K. Seth, S. R. Choudhury, A. Frontera
and S. Mukhopadhyay, 3-Picoline Mediated Self-Assembly of M(II)–Malonate
Complexes (M = Ni/Co/Mn/Mg/Zn/Cu) Assisted by Various Weak Forces Involving
Lone Pair−π, π–π, and Anion···π–Hole Interactions, J. Phys. Chem. B 118 (2014)
14713–14726

ACCEPTED MANUSCRIPT
61. S. K. Seth, A. Bauza and A. Frontera Cryst.Eng.Comm, Screening polymorphism in a
Ni(II) metal–organic framework: experimental observations, Hirshfeld surface analyses
and DFT studies, Cryst.Eng.Comm, 20(2018) 746-754
62. R. Padmavathy, N. Karthikeyan, D. Sathya, R. Jagan, R. Mohan Kumar & K.
Sivakumar, Anion assisted supramolecular self-assemblies of succinate and malate
adducts: crystal structures and theoretical modeling, RSC Adv. 6 (2016) 6, 68468–
68484
63. S. K. Wolf, D. J. Grimwood, J. J. McKinnon, M. J. Turner, D. Jayatilaka and M. A.
Spackmann. Crystal Explorer, University of Western Australia, Australia, 2009
64. R. Padmavathy, N. Karthikeyan, D. Sathya, R. Jagan, R. Mohan Kumar & K.
Sivakumar, Crystal structure, DFT study, hirshfeld surface and PIXEL energy
calculations of benzimidazolium and hexadecylaminium hydrogen maleate salts, J.
Mol. Str., 1136 (2017) 144-156
65. N. Karthikeyan, D. Sathya, R. Padmavathy and K. Sivakumar, Molecular modelling of
an organic salt 4- chloroanilinium hydrogen malonate (4CAHM): crystal structure,
theoretical and Hirshfeld surface analysis Materials Research Innovations, 21 (2017)
304-312

ACCEPTED MANUSCRIPT
List of Figures:
Fig.1 (a)
drawn at 30 % probability level (a) HF method (b) DFT/B3LYP
Fig.1 (b) Optimized Structure of DABCOP with atomic numbering scheme (a) ORTEP diagram
drawn at 30 % probability level (a) HF method (b) DFT/B3LYP
. Optimized Structure of FMP with atomic numbering scheme (a) ORTEP diagram
.
2
1
4
2
2
Fig.2 (a) Ring motifs R1 (6), R2 (4), R2 (4), R1 (6), and R2 (5) diagram for FMP
4
4
Fig.2 (b) Ring motifs R4 (19) and R4 (18) diagram for DABCOP
Fig.3(a) .The packing diagram of FMP viewed down c axis. Dashed line indicate Hydrogen bond
Fig.3(b) .The packing diagram of DABCOP viewed down c axis. Dashed line indicate Hydrogen
bond
Fig. 4 Diagram showing (a) face to face molecule in FMP (b) no face to face molecule when
viewed along a axis
Fig.5. Mulliken charge distribution of (a) FMP and (b) DABCOP
Fig.6a Experimental FTIR spectrum of (a) FMP (b) DABCOP
Fig. 6b Theoretical FTIR spectrum of (a) FMP and (b) DABCOP using HF and DFT/B3LYP
method
Fig.7 Hirshfeld surface analysis of (a) FMP and (b) DABCOP showing possible interaction with
adjacent molecules
Fig. 8 Pie chart showing the relative contribution of all contacts in (a) FMP and (b) DABCOP

ACCEPTED MANUSCRIPT
Table 1 Crystallographic data and Structure refinement Parameters for grown crystals
Empirical formula
Formula weight
C12 H15 N5 O7 [DABCOP]
341.29
C11H10N4O8 [FMP]
326.23
Temperature
Wavelength
293(2) K
0.71073 Å
293(2) K
0.71073 Å
ꢀ
Crystal system, space group
Unit cell dimensions
Monoclinic, P 21/n
a = 11.8306(6) Å alpha = 90°
b = 7.1718(4) Å beta = 93.842(3)°
c = 17.8342(10) Å gamma = 90°
1509.77(14) Å3
Triclinic, P1
a=7.8382(3) Å alpha=107.844(2)°
b=9.3042(6) Å beta=110.246(2)°
c=10.8074(4) Å gamma=92.809(2)°
693.21(6) Å3
Volume
Z, Calculated density
Absorption coefficient
F(000)
4, 1.501 Mg/m3
2, 1.563 Mg/m3
0.125 mm-1
0.136 mm-1
712
336
Crystal size
0.25 x 0.27 x 0.29 mm
0.22 x 0.24 x 0.26 mm
Theta range for data
collection
2.133 to 25.081°
2.140 to 32.079°
Limiting indices
-13 ≤ h ≤ 14, -8 ≤ k ≤ 8, -21 ≤ l ≤ 21
14677 / 2681 [R(int) = 0.0305]
97.70%
-11 ≤ h ≤ 11, -13 ≤ k ≤ 12, -14 ≤ l ≤ 16
18793 / 4829 [R(int) = 0.0246]
100.00%
Reflections collected / unique
Completeness to theta = 25.242
Refinement method
Full-matrix least-squares on F2
2681 / 0 / 221
Full-matrix least-squares on F2
4829 / 3 / 239
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
1.06
1.043
R1 = 0.0567, wR2 = 0.1578
R1 = 0.0755, wR2 = 0.1732
0.402 and -0.319 e.A-3
1508506
R1 = 0.0595, wR2 = 0.1734
R1 = 0.0905, wR2 = 0.1994
0.420 and -0.586 e. A-3
1508507
Largest diff. peak and hole
CCDC No.

ACCEPTED MANUSCRIPT
Table 2 Hydrogen bonding geometry of DABCOP
D-H...A
(Å)
D-H
(Å)
H...A
(Å)
(D...A)
(Å)
D-H...A
(°)
N19-H39...O1
0.81(3)
0.93
1.90(3)
2.4
2.674(3)
3.326(3)
3.509(5)
3.485(5)
3.495(5)
158(3)
171.6
163.7
169.1
164.2
C15-H13...N20(i)
C21-H23...O3(ii)
C33-H34...O6(iii)
C36-H37...O7(iv)
0.97
2.57
2.53
2.55
0.97
0.97
Symmetry transformations used to generate equivalent atoms: (i) x+1/2,-y+3/2,z-1/2 (ii)
x,y+1,z (iii) x-1/2,-y+1/2,z+1/2 (iv) -x+3/2,y+1/2,-z+1/2
Table 3 Hydrogen bonding geometry of FMP
D-H...A
(Å)
D-H
(Å)
H...A
(Å)
(D...A)
(Å)
(D...A)
(Å)
N30-H31...O1
0.93(2)
0.93(2)
0.92(3)
0.92(3)
0.84(3)
0.84(3)
0.93
1.82(2)
2.46(2)
1.95(3)
2.38(2)
2.23(3)
2.69(3)
2.66
2.735(2)
2.935(2)
2.838(2)
2.960(4)
3.072(2)
3.250(2)
3.413(2)
3.414(3)
169(2)
112(2)
160(2)
120(2)
176(2)
126(2)
139(1)
162
N30-H31...O3
N30-H32...O1(i)
N30-H32...O10(i)
N30-H33...O3(ii)
N30-H33...O4(ii)
C23-H24...O7(iii)
C26-H28...O6(iv)
0.97
2.48
Symmetry transformations used to generate equivalent atoms: (i) -x,-y+1,-z+1 (ii) -x+1,-
y+1,-z+1 (iii) -x-1,-y,-z (iv) -x,-y,-z

ACCEPTED MANUSCRIPT
Table 4 Mulliken charge analysis for optimized geometry of DABCOP
HF/6-
DFT6-
Atoms
O1
311++G(d,p) 311++G(d,p)
-0.471
-0.038
0.015
-0.052
-0.053
-0.038
-0.01
-0.307
0.014
0.05
O2
O3
O4
-0.001
-0.003
0.018
0.039
-0.364
-0.233
-0.282
0.268
0.808
-0.468
0.301
-0.555
-0.243
0.291
-0.243
-0.18
O5
O6
O7
N8
N9
-0.282
-0.166
-0.171
0.827
0.8
N10
C11
C12
C13
H14
C15
C16
H17
C18
N19
N20
C21
H22
H23
C24
H25
H26
C27
H28
H29
C30
H31
H32
C33
H34
H35
C36
H37
H38
H39
-0.594
0.355
-0.458
-0.479
0.347
-0.517
-0.032
0.057
-0.174
0.267
0.23
-0.746
0.207
0.203
-0.632
0.202
0.203
-0.209
0.195
0.231
-0.623
0.202
0.206
-0.3
0.076
-0.158
0.252
0.22
-0.624
0.203
0.192
-0.524
0.198
0.19
-0.213
0.192
0.227
-0.519
0.199
0.192
-0.279
0.204
0.25
0.211
0.261
1.023
0.812

ACCEPTED MANUSCRIPT
Table 5 Mulliken charge analysis for optimized geometry of FMP
HF/6-
DFT/6-
Atoms
311++G(d,p) 311++G(d,p)
O1
N2
-0.541
-0.255
-0.064
-0.006
-0.262
-0.036
-0.03
-0.231
-0.013
0.086
0.598
0.033
-0.481
0.259
-0.399
-0.094
0.266
0.219
0.363
0.181
-0.682
0.15
0.952
0.163
-0.364
-0.983
0.231
0.219
-0.134
-0.355
0.566
0.316
0.327
-0.492
0.186
-0.343
-0.265
0.16
-0.278
-0.277
0.171
-0.279
-0.25
0.289
0.023
0.111
0.059
0.183
0.005
0.093
0.048
0.119
0.101
-0.141
0.098
-0.045
0.095
0.034
-0.075
0.162
0.178
-0.263
-0.222
0.294
0.263
0.258
O3
O4
N5
O6
O7
N8
O9
O10
C11
C12
C13
C14
C15
C16
H17
H18
C19
H20
C21
H22
C23
H24
C25
C26
H27
H28
O29
N30
H31
H32
H33

ACCEPTED MANUSCRIPT
Table 6 Experimental and computed FT-IR vibrational frequencies (cm-1) of DABCOP
Experimental HF/6-311++G(d,p) B3LYP/6-311++G(d,p)
Assignment
FT-IR
νcal
1638.49 13.004
aI IR
νcal
aI IR
1503(m)
1508.11
1511.68
1513.15
1533.88
1540.37
1542.97
25.213
22.73
ϕ C-H
1639.61
1642.52
8.031
9.18
ϕ C-H
16.026
12.038
95.766
63.737
33.025
225.914
313.28
423.071
896.174
ϕ C-H
1665.85 49.237
1667.89 4.902
1672.63 25.579
ϕ C-H
γ N-H
ν NO2
1557(s)
1721.74 173.728 1554.21
1748.78 151.587 1576.33
ν N-H
νas NO2
1768.55 41.333
1598.01
β C-H
1630(m)
2618(s)
2962(s)
1801.36 927.562 1632.53
1834.85 1977.16 1707.15
β (C-H) +ν(C-C)(pyrimidine ring)
ν (C-C+C=O)
3209.84 27.702
3210.67 30.059
3217.63 57.714
3238.25 14.056
3239.58 12.865
3244.31 17.548
2671.55
3057.45
3058.35
3061.09
3082.15
3085.78
3087.62
3097.33
3100.26
3100.95
3137.75
3142.55
3110.374 ν N-H...O
27.469
23.046
29.711
9.599
νs C-H
νs C-H
νs C-H
νs C-H
11.613
10.822
0.674
νs C-H
3087(s)
3249.36
3.613
νs C-H
3255.48 25.961
3256.33 26.365
ν as C-H
14.807
14.447
3.094
ν as C-H
3294.74
0.101
ν as C-H
3301.72 18.896
3302.78 13.365
ν as C-H
8.429
ν as C-H
3313.85 1926.61 3144.13
11.253
38.936
19.712
ν as C-H
3403.78
13.74
3222.85
3230.91
ν C-H (pyrimidine ring)
ν C-H (pyrimidine ring)
3427(s)
3409.98 16.801

ACCEPTED MANUSCRIPT
Table 7 Experimental and computed FT-IR vibrational frequencies (cm-1) of FMP
Experiment
al
HF/6-
311++G(d,p)
B3LYP/6-
311++G(d,p)
Assignment
FT-IR
νcal
aI IR
νcal
aI IR
1676
1680
26.922
41.705
1513
1527
1551
1574
1591
1597
1628
1638
1645
1660
1689
2151
3076
298.816
31.724
33.031
132.889
300.199
99.69
β N-H
ν C=C (imidazole ring)
ν C=C ( pyrimidine ring)
β N-H +ν C=O
β (N-H+C-H+C-N)
β N-H
1686 203.902
1723 262.348
1748 208.407
1561(s)
1632(s)
1770
1784 182.786
1801 706.68
62.14
361.256
52.208
201.575
857.281
39.79
β C-N
ϕ(N-H)+β(C-H)
ϕ N-H
1807 220.091
1815 885.099
1846 878.076
ϕ N-H
2066(w)
3086(s)
ϕ N-H
3052
3236
1968.2
10.797
3028.148
12.953
N-H...O interaction
νs C-H (imidazole ring)
3314
3403
3403
3410
1.083
1.807
3145
3232
3239
3245
1.637
14.014
18.581
15.433
νas C-H ( imidazole ring)
ν C-H (pyrimidine ring)
ν C-H (pyrimidine ring)
νas C-H ( imidazole ring)
14.171
18.432
3414
3439
10.093
0.466
3255
3280
11.575
0.248
νas C-H ( imidazole ring)
νs C-H ( imidazole ring)
νs N-H (side chain of imidazole
ring)
νas N-H (side chain of imidazole
ring)
3435(s)
3694
3761
66.366
87.365
3467
3537
30.605
38.476

ACCEPTED MANUSCRIPT
Table 8 The calculated thermodynamical parameters of DABCOP and FMP
DABCOP
HF/6- DFT/6-
311++G(d,p) 311++G(d,p) 311++G(d,p) 311++G(d,p)
FMP
Parameters
SCF energy (a.u.)
HF/6-
DFT/6-
-1259.364
214.511
212.733
-1266.681
199.219
197.442
-1238.986
168.879
167.101
-1246
Total thermal energy (KCal/Mol)
156.639
154.861
Vibrational energy (KCal/Mol)
Zero point vibrational energy
(ZPE) (K Cal/Mol)
201.897
186.413
156.419
143.624
Heat Capacity Cv
(Cal/Mol/Kelvin)
72.171
76.087
69.572
74.355
Entropy S (Cal/Mol-kelvin)
158.731
155.927
156.560
159.691
Dipole moment
µx
µy
µz
14.246
-1.198
-0.854
14.322
14.501
-0.909
-0.794
14.551
-11.672
3.946
-1.707
12.439
-13.661
4.539
-1.353
11.021
µ total
Rotational Constant (GHZ)
X
Y
Z
0.454
0.128
0.106
0.448
0.125
0.104
0.467
0.135
0.108
0.363
0.157
0.135
Table 9 Calculated energy values of FMP and DBCOP
DABCOP
HF / 6- DFT / 6-
311++G (d,p) 311++G (d,p) 311++G(d,p) 311++G(d,p)
FMP
Molecular parameters
(eV)
HF / 6-
DFT / 6-
HOMO
LUMO
-8.894
0.462
-6.772
-3.019
-9.084
0.3808
-6.745
-2.856
ꢀ(EHOMO- ELUMO
)
8.432
3.753
8.704
3.889
Electronegativity (χ)
Chemical potential (µ)
Chemical hardness (h)
Chemical softness (s)
4.216
-4.216
4.678
0.106
4.896
-4.896
3.753
0.133
4.352
-4.352
4.732
0.105
4.787
-4.787
4.800
0.2553

ACCEPTED MANUSCRIPT
Fig.1 (a)
.
Fig.1 (b)
.