Synthesis, thermal and antimicrobial activity of novel organic single crystal of (E)-4-bromo-2-[(phenylimino)methyl]phenol compound

Article abstract of DOI:10.14233/ajchem.2020.22872

This study focused on kinetic modelling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the experimental kinetic curves for the thermal decomposition of (E)-4-bromo-2-[(phenyli

Full text of DOI:10.14233/ajchem.2020.22872

Asian Journal of Chemistry; Vol. 32, No. 11 (2020), 2887-2892
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22872
Synthesis, Thermal and Antimicrobial Activity of Novel Organic Single
Crystal of (E)-4-Bromo-2-[(phenylimino)methyl]phenol Compound
1,*,
1
2
3
R. IDAMALARSELVI
, G. SWETHA , C. RAMACHANDRA RAJA and R. PRISCILLA
1Department of Physics, D.G. Government Arts College for Women (Affiliated to Bharathidasan University, Tiruchirappalli), Mayiladuthurai-
609001, India
2Department of Physics, Government Arts College (Autonomous) (Affiliated to Bharathidasan University, Tiruchirappalli), Kumbakonam-
612001, India
3Department of Physics, A.D.M. College for Women (Autonomous) (Affiliated to Bharathidasan University, Tiruchirappalli), Nagapattinam-
611001, India
*Corresponding author: E-mail: idamalarselvi@gmail.com
Received: 25 June 2020;
Accepted: 19 August 2020;
Published online: 28 October 2020;
AJC-20113
This study focused on kinetic modelling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic
reaction steps, as exemplified by the experimental kinetic curves for the thermal decomposition of (E)-4-bromo-2-[(phenylimino)methyl]-
phenol (4B2PMP) crystal. The crystal was grown by a slow evaporation method. The cell parameters and crystalline perfection of the
grown crystal were studied by single and powder X-ray diffractions. Thermal stability and phase change of 4B2PMP crystal were analyzed
by TG/DTA. The microhardness study has revealed the soft nature. UV-visible analysis reveals the wide range of optical window of the
optical transmission from 199 nm to 1100 nm. The bandgap of the crystal is found to be 3.24 eV. The FESEM of the crystals was
spherically shaped and consisted of a core-shell structure with internal aggregates. The antimicrobial activity of title crystal was tested
against different microorganisms by disc diffusion method. The results reveal that the title compound have effective antimicrobial activities.
Keywords: (E)-4-Bromo-2-[(phenylimino)methyl]phenol, Crystal structure, Kinetic deconvolution analysis.
overall reaction into exothermic and endothermic steps using
simultaneously recorded TG and DSC curves. The results of
kinetic analysis, including the contribution of each reaction
step to the overall reaction, are refined by assuming that the
kinetic data/for overall reaction process is the sum of the two
reaction steps weighted by the contribution of each reaction
steps. Furthermore, strategies for further detailed phenomeno-
logical kinetic characterization. Also, the physico-chemical
kinetic interpretation of mechanical, optical, elastic, micro-
structure is discussed by reviewing the results of the practical
kinetic analysis of the experimental TG-DSC curves for the
thermal decomposition of the crystal 4B2PMP.
Yan et al. [7] reported the crystal structure of 2-(E)-(4-
bromophenyl)iminomethyl]-4-chlorophenol. The crystal structure
has been analyzed in terms of rigid-body motion, molecular
shape, packing arrangement and bond length were discussed.
Muravyev et al. [8] reported the kinetic modelling of a specific
INTRODUCTION
Kinetic analysis of various reaction processes using various
thermoanalytical techniques is widely applied in a different
field with various purpose. Thermoanalytical approaches to
the heterogeneous multistep reactions. However, further comp-
lications are introduced when the overall response comprises
partially overlapping processes with oppositely signed thermo-
analytical signals (e.g., mass loss/gain or exothermic and endo-
thermic events) [1-4].
From the viewpoint of the overall thermal effect revealed
that using DSC, the reaction starts as an endothermic reaction
due to the overall decomposition of (E)-4-bromo-2-[(phenyl-
imino)methyl]phenol (4B2PMP) crystal and becomes the exo-
thermic evaporation/decomposition of the in situ produced
residual mass of the crystal [5,6]. This study focuses on the
establishment of a methodology for kinetic modelling of an
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2888 Idamalarselvi et al.
Asian J. Chem.
type of multistep heterogeneous reaction comprising exo-
thermic and endothermic reaction steps, as exemplified by the
practical kinetic analysis of the experimental kinetic curves
for the thermal decomposition of molten ammonium dinitramide
(ADN). Nakano et al. [9] reported the kinetic modelling of
the thermal decomposition of sodium percarbonate (sodium
carbonate-hydrogen peroxide (2/3)). The reaction is characterized
by apparently different kinetic profiles of mass-loss and exo-
thermic and endothermic behaviour as recorded by TG/DSC
analysis.
RESULTS AND DISCUSSION
XRD analysis: The synthesized (E)-4-bromo-2-[(phenyl-
imino)methyl]-phenol (4B2PMP) crystal was subjected to single
crystal X-ray diffraction (SXRD) analysis using Bruker AXS
KappaAPEX-II single-crystal X-ray diffractometer, equipped
with graphite monochromated MoKα radiation (λ = 0.710 Å)
at room temperature. The single-XRD analysis (Fig. 1a) confirmed
that the grown crystal belongs to the orthorhombic crystal
system with the space group of Pca21 (Table-1) [13].
The concept about the levels of structure is developed,
which include the concept in equilibrium and kinetics, the
geometry of a crystal, the arrangement of atoms in the unit cell
of crystalline material, the microstructure of the material. The
novelty of the work focuses on the establishment of a methodology
for kinetic modelling of an overall reaction into exothermic
and endothermic steps using simultaneously recorded TG and
DSC curves [10-12]. The synthesized 4B2PMP crystal was
primarily parted for their in vitro growth constraint activity
against a different strain of bacterial and fungal.
TABLE-1
COMPARISON OF POWDER AND SINGLE
XRD DATA FOR 4B2PMP CRYSTAL
Molecular formula
Molecular weight
C13H10BrNO
276.13 g/mol
Crystal system, space group Orthorhombic, Pca21
Unit cell
a (Å)
b (Å)
c (Å)
Single XRD
12.353 Å
4.5092 Å
19.778 Å
90°
90°
90°
1107 Å3
Powder XRD at 200 °C
12.567 Å
4.876 Å
19.191 Å
90°
90°
90°
1101 Å3
α
β
γ
EXPERIMENTAL
Volume (Å3)
The chemicals viz. 5-bromo-2-hydroxybenzaldehyde and
aniline used in the present work were of analytical reagent (AR)
withaminimumassayof99%andobtainedfromE-Merck, Germany.
Synthesis of (E)-4-bromo-2-[(phenylimino)methyl]-
phenol (4B2PMP) crystal: 5-Bromosalicylaldehyde (0.4g,
0.004 mol) was dissolved in a mixture of CCl4 (5 mL) and
DMSO (5 mL). To this solution, aniline (0.372 g, 0.0035mol)
was added dropwise with constant stirring for 1 h and the
solution turned deep yellow. On standing for 1 week and with
slow evaporation of solvent, orange crystal is obtained.
Antimicrobial activities: The antimicrobial activities of
4B2PMP crystal were analyzed by the disk diffusion method.
Test pathogens (E. lenta, S. epidermis, B. substilis, S. mutans,
E. faecalis, K. pneumoniae, P. aeruginosa, E. coli, C. albicans
and A. niger) were spread on Mueller-Hinton agar (MHA) plates.
A well of diameter 6 mm was made using a sterile cork borer
and loaded with a required concentration of drug over the agar.
The test plates were incubated for 24 h at 37 ºC. The zone of
inhibition (mm in diameter) was taken as the activity against
the test pathogens.
Powder X-ray diffraction analysis: The grown 4B2PMP
crystal was subjected to PXRD analysis using CuKα (λ =
1.54060 Å) radiation with the help of pan analytical Xpert-
pro X-ray diffractometer in the 2θ values ranging from 10º to
80º. Ind X software was used to index the corresponding peaks.
Fig. 1b shows the diffraction profile peaks of 4B2PMP sample
calcined at 300 ºC for 3 h with promise pure orthorhombic
crystal system for the 4B2PMP powder with the space Pca21.
It is pure from the diffraction pattern of the crystalline in nature.
The sample shows major peak assigned to the 21.643º of the
peak 2θ values 14.305º and 35.194º with interplan of spacing
corresponding to diffraction planes of 2 0 0, 0 1 2, 1 1 4 and 4 1 0
(Table-1). The thermally induced growth mechanisms each to
increase in the grain size, which may be due to the reduce FWHM
value (Table-2). Determination of density in dislocation crystal
explain the defect the unit volume of the sample.
Thermoanalytical measurements: Thermal studies with
crystals can predict a product′s performance and thermal history
35000
60000
012
201
30000
50000
(a)
(b)
25000
40000
20000
004
110
30000
200
15000
006
20000
10000
402
010
114
410
10000
0
5000
0
10
15
20
25
30
(°)
35
40
45
50
10
20
30
40
50
60
2
θ
2θ (°)
Fig. 1. (a) High temperature, (b) Room temperature powder XRD spectrum of 4B2PMP

Vol. 32, No. 11 (2020)
Synthesis of Novel Organic Single Crystal of (E)-4-Bromo-2-[(phenylimino)methyl]phenol 2889
TABLE-2
STRUCTURAL PARAMETERS OF POWDER XRD FOR 4B2PMP CRYSTAL
Sample
5BSA (RT)
5BSA (HT-300 °C)
h k l
2 0 0
2 0 2
FWHM
0.23
0.06
Crystallize size (D) (nm)
2θ (°)
15.358
21. 643
Dislocation density (δ)
3.5223
12.31
8.06
6.60
of the sample in uses i.e. its thickness, stability, melting point,
crystal perfection, orientation and phase transition which can
be accurately measured. The % of weight loss data (TG curve)
from a 3.332 mg sample run under vacuum and with the
analysis of nitrogen gas showed the loss of -90.21% at 420 ºC
(1st weight loss) and a slow loss of -91.93% (2nd weight loss)
starting around 489 ºC. The sample was measured for its real
density and the resulting data are shown on the DTA curve,
undoubtfully the sharp exotherm at 325.6 ºC represents a phase
change (Fig. 2). DSC thermogram indicates the exothermic
and endothermic patterns. The first sharp endotherm at 123.1
ºC is an indicative of the heat capacity enthalpy of crystallization.
Second sharp exotherm at 333.5 ºC is due to the enthalpy of
melting. Exothermic behaviour (without decomposition) was
chemically associated with the decreasing enthalpy. Narrow
exotherm usually indicates crystallization (orderly) of a meta-
stable system, which is directly proportional to the amount of
heat energy disrobed by the sample. The negative values of enth-
alpy referred to the chemical bond formed and heat is released.
This study focused on kinetic modelling of a specific type of
multistep heterogeneous reaction comprising exothermic in
signal step and endothermic reaction step, as exemplified by
the practical kinetic analysis of the experimental kinetic curves
for the thermal decomposition of 4B2PMP crystal.
The important result of the present kinetic approach of
separating the exothermic and endothermic reaction steps of
thermal decomposition of 4B2PMP is that the net thermal effect
of each reaction step, Q1 and Q2 and the relationship of these net
thermal effects to the gross thermal effects. The QΣ = 1133.35 J
of the overall reaction process, can be estimated using the
kinetic parameters. To evaluate the thermal anomaly of the
crystal, the enthalpy of fusion (∆Hf), entropy of fusion (∆Sf),
Gibbs free energy (∆Gf), activation energy (Εa), thermal
conductivity (w), heat capacity and specific heat capacity (Cp)
were measured (Table-3). The specific heat capacity displays
abrupt change due to the implementation of the configurational
TABLE-3
THERMODYNAMICAL DATA FOR 4B2PMP SINGLE CRYSTAL
Phase transition
325.6 °C
73.67
0.5984
21953
232.7
Enthalpy of fusion ∆Hf (kJ mol-1)
Entropy of fusion ∆Sf (J k-1mol-1)
Gibbs free energy ∆Gf (Jk-1mol-1)
Activation energy Eac (kJmol-1)
Specific heat capacity (Cp) J/g ºC
Heat capacity (Q) J
1.40 - Endo
471.68 - Endo
4.48 Exo
-2895.2 - Exo
degree of kinetic freedom of rotational and atom transfer. In
the system, heat is absorbed and realized simultaneous due to
positive and negative enthalpy reactions [14-23].
Activation energy: An Arrhenius method is used to
measure the activation energy of the phase transition. The value
obtained for the phase change in high-temperature is Ea = 232.7
kJ/mol. This represents the adequate energy that stimulates
both nucleation and development.Activation energy associated
with each stage of decomposition is described by the equation.






Ea
R
1
y
1


ln ln
= −
+ Constant





T





Mechanical stability and elastic properties: The hard-
ness of the crystal and the elastic properties such as young, bulk
and shear module were calculated at a particular temperature.
The experiment was carried out in the load range from 5 to
50 g over a fixed interval time of 5 s. The indentation patterns
were measured by the optical microscope. The hardness number
(Hv) was calculated using the following standard eqn.:
P
d2


HV =1.8544X
Kg/mm2




where P is the applied load and d is the diagonal length.
It is shown that the hardness number increases upto 50 g
and then decreases with increasing load Fig. 3a. It may be due
to the reverse indentation size effect (RISE) and it is attributed
1
1st Mass change: -90.21%
Endo peak 123 °C, 0.4718 mW/mg
120
0
110
100
90
80
70
60
50
40
30
20
10
0
0
-2
-4
-1
-6
Area 73.67 J/g
-2
Area -21 J/g
-8
Residual mass: 8.07%
-10
-12
-3
(a)
(b)
Exo peak 333 °C, -2.988 mW/mg
2nd Mass change: -91.23%
-4
100
200
300
400
500
100
200
300
400
500
Temperature (°C)
Temperature (°C)
Fig. 2. (a) TG -DTA curve and (b) DSC curve of 4B2PMP

2890 Idamalarselvi et al.
Asian J. Chem.
10
graph was plotted between log P versus log d (Fig. 3b) and it
provides the straight line and works hardening coefficient (n)
is assessed from the slope. The n value is determined to be
2.97, which is higher than 2, reveals the soft nature of 4B2PMP.
9
8
7
6
5
4
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0
5
10 15 20 25 30 35 40 45 50 55
Load P (g)
Fig. 3a. Vickers microhardness spectrum of 4B2PMP single crystal with
applied load
to the predominance of nucleation, the existence of distorted
zone near the crystal interface, an effect of vibrations, specimen
chipping around the indentation, radial cracks and multipli-
cation of dislocations of the sample. The maximum hardness
number of the grown crystal was found to be 9.18 kg/mm2 and
it evidences good mechanical stability (Table-4).
0.6
1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.05
Log d
Fig. 3b. Plot of log P vs. log d of 4B2PMP crystal
UV-Vis analysis: The optical study was performed using
UV-vis/NIR spectrophotometer (Perkin-Elmer Lambda 35).
UV visible spectra obtained for representative 4B2PMP crystal
from 199 nm to 1100 nm. The absorption spectrum in Fig. 4
shows a lower cut off wavelength 346 nm at room temperature
and 350 nm at 300 ºC. 4B2PMP crystal is said to exhibit π-π*
P = Kdn
log P = log K + n log
where P is the applied load (g); d is the diameter of recovered
indentation (mm) and K is the material constant. The Meyer's
TABLE-4
MECHANICAL AND ELASTIC DATA OF 4B2PMP CRYSTAL
Young’s modulus E
(N/m2)
Bulk modulus B
Shear modulus G
(N/m2)
Vickers hardness (Hv)
Stress (σ)
Strain (ε)
(N/m2)
0.1576
0.767
1.933
2.292
3.062
4.53
6.18
8.62
8.82
9.18
0.109
0.221
0.340
0.404
0.497
0.171
0.071
0.043
0.043
0.040
0.640
3.110
7.839
9.292
12.41
0.361
1.757
4.429
5.250
7.014
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
4
(a)
(b)
3
2
1
0
-0.5
200 300 400 500 600 700 800 900 1000 1100
Wavelength (nm)
200 300 400 500 600 700 800 900 1000 1100 1200
Wavelength (nm)
Fig. 4. UV-visible absorption spectrum of 4B2PMP crystal at room temperature (a) and 300 ºC (b)

Vol. 32, No. 11 (2020)
Synthesis of Novel Organic Single Crystal of (E)-4-Bromo-2-[(phenylimino)methyl]phenol 2891
transition [24,25]. The transmittance (T) of 4B2PMP crystal
is used to determine the general equation:
be 7.37 1.37 mol% from the mass loss value during the
thermal decomposition of 4B2PMP crystal [26].
The elemental analysis was carried out by EDAX for the
4B2PMP crystal, the average atomic percentage and weight
percentage are shown. From the weight% bar chart, it was
evident that the major component of the crystal mixture. The
content varied in the order C > Br > O > Al by which the
component was mixed experimentally.
Antimicrobial studies: The MIC values (Table-5) specified
that the synthesized 4B2PMP crystal exhibited a promising
results compared to the ligand against tested microorganisms
(E. lenta, S. epidermis, B. substilis, S. mutans, E. faecalis, K.
pneumoniae, P. aeruginosa, E. coli, C. albicans and A. niger).
An enhancement in the activity may be efficient on the basis
that ligands mainly possess C=N bond. The outcome of anti-
microbial activity evaluation of the synthesized compounds
revealed that the synthesized 4B2PMP compound possessed
antibacterial and antifungal activities. The 4B2PMP compound
displayed moderate antibacterial activity at MIC = 50 and 250
µg/mL and good antifungal activity at MIC= 50 µg/mL against
tested bacteria and fungi, respectively.
Planks constant (h)×Speed of light (c)
Energy (E) =
Wavelength (λ)
where, energy (E) = Bandgap, Plank′s constant (h) = 6.626 ×
10-34 J/s, velocity of light (c) = 2.99 × 108 m/s and wavelength
(λ) = absorption peak value, also 1 eV = 1.6 × 10-19.
The linear part is extrapolated and intercept in x coordi-
nates and the band value wass found to be 3.61 eV at room
temperature and 3.57 eV at 300 °C. This high-temperature
band gap to the optical colour changed in the transparency of
the crystal is especially suited for the thermochromic appli-
cation.
FESEM-EDAX analysis: The shape, size and distribution
of the crystal, as prepared composite sample and microstructure
were examined using a super 55 CARL ZEISS FESEM-EDAX.
Fig. 5 shows the field scanning electron microscopic images
of the 4B2PMP crystal, which reflects that crystals were spheri-
cally shaped and consisted of a core-shell structure with internal
aggregates of 4B2PMP crystalline particles radiating from the
centre and covered by a surface layer composed of 4B2PMP
crystalline particles. The molar fraction of C13H10NOBr in
4B2PMP crystals used in the present study was calculated to
Conclusion
A novel organic material (E)-4-bromo-2-[(phenylimino)-
methyl]phenol (4B2PMP) was synthesized with improved heat
Quantitative results
40
30
20
10
0
C
O
Al
Br
Fig. 5. FESEM micrograph and weight percentage of 4B2PMP corresponds to the different scale bar
TABLE-5
ANTIMICROBIAL ACTIVITIES OF 4B2PMP CRYSTAL
Strain
E. lenta
50 µg
–
9 mm
11 mm
–
–
–
–
100 µg
11 mm
11 mm
12 mm
–
–
–
–
–
250 µg
12 mm
14 mm
13 mm
–
12 mm
–
10 mm
–
500 µg
14 mm
17 mm
15 mm
13 mm
14 mm
10 mm
12 mm
18 mm
22 mm
26 mm
Positive control
34 mm
S. epidermis
B. substilis
S. mutans
E. faecalis
K. pneumoniae
P. aeruginosa
E. coli
30 mm
33 mm
41 mm
32 mm
32 mm
31 mm
42 mm
21 mm
–
–
C. albicans
A. niger
12 mm
21 mm
14 mm
25 mm
14 mm
17 mm

2892 Idamalarselvi et al.
Asian J. Chem.
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The authors gratefully acknowledge SAIF, IIT Madras,
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Centre, Sathyabama University, Chennai, India for FESEM-
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CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
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