Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study

Article abstract of DOI:10.1515/chem-2020-0172

The corrosion behavior of copper in 0.1 M aqueous sulfuric acid medium has been studied using potentiodynamic polarization measurements, quantum chemical calculations, and molecular dynamic simulations in the presence and absence of (2E,5E)-2,5-dibenzylidenecyclopentanone (M1) and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone (M2). The compounds were freshly prepared in high yields via the Claisen-Schmidt reaction between the cyclopentanone and the corresponding aryl aldehyde. The results from the potentiodynamic measurements imply that M1 and M2 act as mixed inhibitors due to their adsorption on the copper surface. The more pronounced corrosion inhibition performance of the M2 molecule in comparison to M1 was related to the fact that this molecule contains two basic nitrogen atoms (in 4-dimethylamino group).

Full text of DOI:10.1515/chem-2020-0172

Open Chemistry 2020; 18: 1412–1420
Research Article
Veprim Thaçi, Ramiz Hoti, Avni Berisha*, Jane Bogdanov*
Corrosion study of copper in aqueous sulfuric acid solution in
the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and
(
2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone:
Experimental and theoretical study
https://doi.org/10.1515/chem-2020-0172
received February 29, 2020; accepted August 25, 2020
1
Introduction
Abstract: The corrosion behavior of copper in 0.1 M aqu-
eous sulfuric acid medium has been studied using potentio-
dynamic polarization measurements, quantum chemical
calculations, and molecular dynamic simulations in the
presence and absence of (2E,5E)-2,5-dibenzylidenecyclo-
pentanone (M1) and (2E,5E)-bis[(4-dimethylamino)benzy-
lidene]cyclopentanone (M2). The compounds were freshly
prepared in high yields via the Claisen–Schmidt reaction
between the cyclopentanone and the corresponding aryl
aldehyde. The results from the potentiodynamic measure-
ments imply that M1 and M2 act as mixed inhibitors due to
their adsorption on the copper surface. The more pro-
nounced corrosion inhibition performance of the M2 mo-
lecule in comparison to M1 was related to the fact that this
molecule contains two basic nitrogen atoms (in 4-di-
methylamino group).
Among the nonferrous metals, copper, due to its desirable
properties, is among the most utilized. Even though it is
known for its durability (in neutral aqueous systems),
under certain conditions it is prone to corrosion [1,2].
Copper and its alloys are frequently used in different types
of chemical equipment. In general, copper cannot displace
hydrogen from acid solutions without the presence of dis-
solved oxygen [3]. However, most solutions contain dis-
solved air and are acidic. Corrosion inhibitors in many
cases are employed to prevent copper corrosion. Control
of copper corrosion is of immense technical, environ-
mental, and economical importance. One simple and effec-
tive way to eliminate or slow down these processes is to use
corrosion inhibitors [4–7]. Generally, the copper corrosion
inhibitors are classified into inorganic and organic inhibi-
tors. Lately, the organic inhibitors have been preferred and
most of them are derivatives of benzotriazole [8,9]. How-
ever, serious environmental concerns have been raised
over the extensive use of these types of additives, due to
their persistence in sediments, resistance to degradation,
and toxicity to aquatic organisms [10]. The quest for novel
Keywords: copper corrosion, (2E,5E)-2,5-dibenzylidene-
cyclopentanone, (2E,5E)-bis[(4-dimethylamino)benzylidene]
cyclopentanone, sulfuric acid medium, computational study
“green” copper corrosion inhibitors is ongoing.
Almost all of the relevant inhibitors are organic com-
pounds containing one or more heteroatoms of which the
most frequently encountered are nitrogen, oxygen, phos-
phorus, and sulfur. The corrosion protection performance
exhibited by these organic compounds depends on the
heteroatom present and usually decreases in the fol-
lowing order: O > N > S > P [11,12], but one has to be
careful with such generalizations and take into consid-
eration the functional group and steric factors. A vast


*
Corresponding author: Avni Berisha, Department of Chemistry,
FNMS, University of Pristina “Hasan Prishtina”, 10000 Pristina,
Republic of Kosovo, e-mail: avni.berisha@uni-pr.edu
*
Corresponding author: Jane Bogdanov, Department of Organic
Chemistry, Institute of Chemistry, Faculty of Natural Sciences and
Mathematics, Ss. Cyril and Methodius University, 1000 Skopje,
Republic of Macedonia, e-mail: janebogdanov@gmail.com
Veprim Thaçi: Department of Chemistry, FNMS, University of
Pristina “Hasan Prishtina”, 10000 Pristina, Republic of Kosovo;
Department of Organic Chemistry, Institute of Chemistry, Faculty of
Natural Sciences and Mathematics, Ss. Cyril and Methodius
University, 1000 Skopje, Republic of Macedonia
number of molecules such as plant extracts, drugs, and
synthetic organic molecules have been demonstrated to
have good copper corrosion inhibition properties [13–18].
Many of the green renewable organic molecules,
such as vanillin (plant-derived flavor compound) [15],
caffeine [19], and other naturally occurring molecules,
Ramiz Hoti: Department of Chemistry, FNMS, University of Pristina
“
Hasan Prishtina”, 10000 Pristina, Republic of Kosovo
Open Access. © 2020 Veprim Thaçi et al., published by De Gruyter.
This work is licensed under the Creative Commons Attribution 4.0
International License.

Corrosion study of copper in aqueous sulfuric acid solution in the presence of M1 and M2

1413
can be used as copper corrosion inhibitors. During our inexpensive industrially available chemicals (cyclopenta-
literature search for new potential copper corrosion inhi- none, benzaldehyde, and 4-(dimethylamino)benzaldehyde).
bitors, we have encountered simple organic compounds
Furthermore, if these compounds are promising, more deri-
with a unique electronic structure, so-called monocar-
bonyl analogs of curcumin (MACs). They have been ex-
tensively studied for their biological activity [20,21], but
they have not been explored for corrosion inhibition of
metals. The application of these MACs as corrosion inhi-
bitors would broaden the range of compounds investi-
gated and may lead to new insights into the mechanisms
of the inhibitory action. After our investigation of the
vatives can be easily synthesized and subjected to corrosion
inhibitionstudies until the optimal derivativeis found. Inthis
study, two different compounds: (a) (2E,5E)-2,5-dibenzylide-
necyclopentanone (M1) and (b) (2E,5E)-bis[(4-dimethyla-
mino)benzylidene]cyclopentanone (M2) were used as corro-
sion inhibitors of copper in 0.1 M aqueous sulfuric acid
medium. From the theoretical perspective, the adsorption
structural features of MACs based on the 2,5-diarylidene- mechanism and inhibition performance of M1 and M2 were
cyclopentanone core and following the cyclic voltam- surveyed as corrosion inhibitors by means of DFT at the
metry measurements, we have decided to explore their B3LYP/6-31G (d,p) basis set level. Furthermore, molecular
corrosion-inhibiting properties. The choice was to use
the “parent” compound, (2E,5E)-2,5-dibenzylidenecyclo-
pentanone (M1), and also the derivative with electron-do-
nating dimethylamino substituent, (2E,5E)-bis[(4-dimethyl-
amino)benzylidene]cyclopentanone (M2). Moreover, these
kinds of derivatives are expected to be more eco-friendly
than the benzotriazoles and related derivatives, because
they are susceptible to retro-Claisen–Schmidt reaction and
can revert back to the starting aldehyde and cyclopenta-
none, which are biodegradable. An additional useful feature
is that M2 is fluorescent [14–16] as a free amine and the
fluorescence is quenched under acidic conditions (i.e., up-
dynamics (MD) simulations were applied to calculate the
adsorption geometries of the adsorbate, which was further
explored by DFT with plane-wave basis set calculations to
evaluate more precisely adsorption energies and the interac-
tion with copper surface. Herein, we present the combined
experimental and theoretical approach intended to gain in-
sights into the potential of the 2,5-diarylidenecyclopenta-
nones as copper corrosion inhibitors under acidic conditions.
on protonation of the dimethylamino group). These 2,5-dia- 2 Materials and methods
rylidenecyclopentanones are known compounds and their
structure and properties have been thoroughly investigated
2
.1 Experimental section
(Scheme 1) [22–26].
These derivatives are synthetically accessible, their
properties can be finetuned via synthesis, and finally
they are not computationally demanding. Density func-
tional theory (DFT) has become an expedient method to
interpret experimental results, allowing the researcher to
attain dependable structural parameters for molecules of
various complexities [11,27,28]. This is also applicable to
corrosion studies, where DFT allows accurate prediction
of the inhibition efficiency (IE) of organic corrosion inhi-
bitors on the basis of electronic and molecular properties
as well as reactivity indexes [29]. Cost effectiveness is an
important parameter when synthetic inhibitors are used
2
.1.1 Reagents and instruments
Cyclopentanone (99.8%), benzaldehyde (98%), and 4-(di-
methylamino)benzaldehyde were obtained from Sigma-
Aldrich. Methanol (99.9%, Chromasolv HPLC grade), di-
chloromethane, ethyl acetate, ammonium chloride, and
sodium hydroxide were obtained from Merck. All the che-
micals were used as received. Melting points were deter-
mined using Buchi B-545 melting-point apparatus. In-
frared spectra were recorded on a Varian 3100 FTIR instru-
1
13
ment by preparing solid samples as KBr pellets. H and C
NMR spectra were obtained on a Bruker Avance 400 MHz
spectrometer (at 400 and 100 MHz, respectively) in d6-
chloroform as a solvent and tetramethylsilane (TMS) as
an internal standard. Chemical shifts were measured re-
[
16]. The studied inhibitors suggested here offer the advan-
tage of being synthesized in a single step using relatively
lative to TMS or the residual solvent in CDCl . The UV-Vis
3
spectra were recorded on Helios Alpha Spectrophotometer
on Cary 50 spectrophotometer in acetonitrile as a solvent.
For the potentiodynamic measurements, 97% sul-
furic acid (Pro analysis; Merck, UN-No. 1830 Darmstadt,
Germany) was used. This reagent was appropriately di-
luted with distilled water until a final concentration of
Scheme 1: Chemical structures of (2E,5E)-2,5-dibenzylidenecyclo-
pentanone (M1) and (2E,5E)-bis[(4-dimethylamino)benzylidene]
cyclopentanone (M2) inhibitors.

1
414

Veprim Thaçi et al.
3
sulfuric acid of 0.1 mol/dm was obtained, and this electro- above using cyclopentanone (0.8412 g, 10 mmol) and
lyte was used throughout the electrochemical measure- 4-(dimethylamino)-benzaldehyde (2.9838 g, 20 mmol). Re-
ments. The electrode was made of commercial copper crystallization from ethyl acetate gave 2.21 g (64%) of the
(
d = 1 mm) wire. Before the electrochemical measurements, desired product (M2) as orange powder. m.p. 302–304°C
1
the copper surface was mechanically polished with emery (Lit. 298°C, [14]; >300°C [16]). H NMR (400 MHz, CDCl ):
3
paper, followed by cleaning with distilled water and then δ 7.58–7.48 (m, 6H), 6.73 (d, J = 8.9 Hz, 4H), 3.07 (s, 4H),
13
degreased in ethanol, washed with distilled water again, 3.03 (s, 12H). C NMR (100 MHz, CDCl ): δ 196.04 (C]O),
3
and air-dried. The linear sweep voltammetry (LSV) was 150.73, 133.52, 133.50, 132.54, 124.28, 111.89, 77.01, 76.70,
−1
performed using a PalSens3 potentiostat and applying a 40.13, 26.66. FT-IR (KBr): 1,673 cm (w, C]O). UV-Vis
three-electrode cell assembly. A saturated calomel elec- (CH CN): λ
= 480 nm.
3
max
trode(SCE)andaplatinumelectrodewereusedasreference
and auxiliary electrodes, respectively. All solutions were
prepared from analytic-grade chemicals and doubly dis-
tilled water. The copper electrode was allowed to stabilize
its open circuit potential (OCP) until the potential sta- 2.2 Computational details
bilization met the criteria of dE/dt limit 10− V/s. Poten-
6
tiodynamic polarization was carried out by scanning the 2.2.1 DFT Calculations
potential ±500 mV from the evaluated OCP using a scan
−1
rate of 1 mV s .
DFT calculations were performed using Orca software
31,32]. The UV-Vis spectra and the rotation energy bar-
[
rier for the studied molecules are computed using the
DFT method by taking a relaxed geometry scan of 15
degree from 0° to 360° (25 energy calculations) along
2
.1.2 Synthesis of 2,5-diarylidenecyclopentanones
(
2E,5E)-2,5-Dibenzylidenecyclopentanone (M1) was pre- the dihedral angle presented in Section 3 using the
pared by adaptation of the procedure described by Hadzi- B3LYP exchange–correlation density functional and the
Petrusev et al. [30]. Cyclopentanone (0.6309 g, 7.5 mmol) 6-31G** split-valence Pople basis sets.
and benzaldehyde (1.5918 g, 15 mmol), followed by methanol
(10 mL), were added in a round-bottomed flask (25 mL)
equipped with a condenser. The solution was stirred at am- 2.2.2 Monte Carlo (MC) and MD simulations
bient temperature for 5 min; as a next step, a 20% (w/v)
aqueous solution sodium hydroxide (2.0 mL) was added MC and MD calculations were accomplished using Materials
dropwise over a 5 min period. At first, the reaction mixture Studio 7.0 [33,34]. The interaction between iron surface and
turned yellow and soon (after a few minutes) the yellow the inhibitor in the simulated corrosion media for MC is
precipitate appeared. The reaction mixture was stirred for estimated bythe slab model of Cu(11)with periodicboundary
4
5 min at ambient temperature. The reaction flask was low- conditions (using a Cu unit cell, cleaved at the h k l(1 1)plane
ered into an ice bath to be kept for 10 min, then 5 mL of water and expanded to 10 × 10 with addition of an 30A vacuum
was added, and the content was filtered on a Büchner fu- layer at the C axis, containing 200 water molecules/one in-
nnel. During the next stage, the yellow solid was washed hibitor molecule [either M1 or M2 molecule]/25 ethanol mo-
with saturated aqueous ammonium chloride solution (1 × lecules and 60 hydronium + 30 sulfate ions). To assess the
1
0 mL), distilled water (3 × 10 mL), and ice-cold methanol adsorption configurations (COMPASS II force field, energy
−5
(
5 mL). The obtained yellow solid (1.68 g) was dried in vacuo. convergence tolerance of 2 × 10 kcal/mol, force conver-
Recrystallization from hot methanol and dichloromethane gence tolerance of 0.001 kcal/mol/Å) and the interaction
gave 1.63 g (82%) of the desired product (M1) as yellow between the molecules and the substrates, the Metropolis
powder. m.p. 189–191°C (Lit. 196–198°C, [14]; 194–195°C Monte Carlo method was applied.
1
[
18]; 189–193°C [17]); H NMR (400 MHz, CDCl ) δ: 7.68–
The MD simulations were performed using COMPASS
3
7
.55 (m, 6H), 7.49–7.41 (m, 4H), 7.38 (dd, J = 8.4, 6.2 Hz, II (Condensed-phase Optimized Molecular Potentials for
13
2
H), 3.13 (s, 4H). C NMR (100 MHz, CDCl ): δ 196.37 (C]O), Atomistic Simulation Studies) force field [35]. Prior to the
3
1
1
37.30, 135.83, 133.85, 130.73, 129.37, 128.76, 26.56. FT-IR (KBr): use in the MD simulations, the slab model containing the
−1
,692 cm (m, C]O). UV-Vis (CH CN): λ
= 354 nm.
corrosion media and the inhibitor molecule was opti-
2E,5E)-2,5-Bis[(4-dimethylamino)benzylidene]cyclo- mized with the Smart optimization algorithm, whose
pentanone (M2) was prepared using the procedure outlined energy convergence criteria were at the level of
3
max
(

Corrosion study of copper in aqueous sulfuric acid solution in the presence of M1 and M2
−3

1415
0− kcal/mol and force criteria of 5 × 10 kcal/mol/Å.
4
1
We use NVT (constant-temperature, constant-volume) ca-
nonical ensemble at 298 K to conduct MD. The time step
for MD was 1 fs, and for the total simulation −500 ps. We
controlled the system temperature with Berendsen Ther-
mostat (0.1 ps decay constant) [36]. Furthermore, 500 ps of
trajectory frames were used for the radial distribution
function (RDF) analysis.
Ethical approval: The conducted research is not related to
either human or animal use.
3
Results and discussion
Figure 1: Semilogarithmic polarization plots of the copper electrode
in a 0.1 M H SO (70:30 water:ethanol) aqueous solution with and
without the presence of 0.001 mol/dm : M1 and (b) M2. Reference
SCE. v = 1 mV/s.
3
.1 Linear polarization
2
4
3
The compounds (2E,5E)-2,5-dibenzylidenecyclopentanone
M1) and (2E,5E)-bis[(4-dimethylamino)benzylidene]cy-
(
Table 1: Results of Tafel slope analysis of the polarization plots
at 298 K
clopentanone (M2) were freshly prepared via the Claisen–S
chmidt reaction between the cyclopentanone and corre-
sponding aryl aldehyde in 82 and 64% yields, respectively.
They are known compounds (dienones) with E, E stereo-
chemistry and their spectroscopic data match those re-
ported in the literature [22,25].
The polarization plots obtained for the copper elec-
trode in a 0.1 M sulfuric acid aqueous solution in the Anodic β Tafel constant
presence and the absence of M1 and M2 are presented (V/decade)
in Figure 1. Potentiodynamic measurements for the Cu
electrode showed a fast increase of the anodic current,
after the corrosion potential. This is due to an active dis-
solution of copper at a slightly positive potential, around
Corrosion parameters
Blank
M1
M2
E corrosion (V)
j corrosion d (A/cm²)
Polarization
−0.023
1.195
2.86 × 10
−0.067
1.026
3.68 × 10
0.004
0.468
5.09 × 10
4
4
4
Resistance (Ω)
0.091
0.104
0.537
0.063
0.445
Cathodic β Tafel constant 0.564
V/decade)
Corrosion rate (mm/year) 0.441
IE (%)
(
0.378
14.142
0.173
60.840
—
0.08 V. The inhibition behavior of both the studied mo-
lecules (M1 and M2) is evidenced by the decreased
cathodic current densities. The cathodic and anodic Tafel
slopes and corrosion potential (Ecorr), kinetic electroche-
mical corrosion parameters, and corrosion current den-
sity (Icorr) were calculated from the extrapolation of Tafel
plots (values in Table 1).
IE (%) = (I
) − (I )/(I
) × 100.
unhib.
inh.
unhib.
The calculated IEs for M1 and M2 were 14.1 and 60.8%,
respectively, and the corrosion rates were 0.378 mm/year
and 0.173 mm/year, respectively.
Albeit the corrosion current density decreases in the
presence of M1 and M2, there is no apparent corrosion 3.2 UV-Vis spectroscopy
potential change significantly in the presence of these in-
hibitor molecules. The cathodic Tafel slope is larger than To fully understand the copper corrosion inhibition beha-
that of the anodic one, and the corrosion potential is viorof these derivatives, whichhavea unique π-conjugated
slightly displaced cathodically, showing that the protective structure, information on both the ground-state and ex-
barrier formed from the adsorbed molecules acts mainly as cited-state structures and the frontier molecular orbitals
a cathodic inhibitor. We calculated the IE using the corro- was helpful. This was a preliminary study to see what are
sion current density of the metal electrodes in the absence thechangesuponelectronic excitation. BothM1andM2are
and presence of the inhibitor, with the following equation: colored in the solid state and solution (yellow and bright

1
416

Veprim Thaçi et al.
orange, respectively). The UV-Vis spectra were recorded in (insets on the UV-Vis spectra). Distributions of NTOs for
acetonitrile (200–800 nm) and M1 and M2 had absorption the transition state at lower wavenumbers are mainly
maxima at 354 and 480 nm, respectively. Both compounds from benzene rings toward the central cyclopentanone
have relatively high molar extinction coefficients (ε): ε
=
moiety. The absorption at the higher wavelengths is elec-
(
M1)
−1
−1
−1
−1
1
5,983 M cm and ε(
= 6,99,24 M cm . M2 is also tronic transition from the π system of the aromatic side
M2)
fluorescent and the fluorescence is solvent dependent. rings to the double bond that links the phenyl ring with
This may be a useful feature to further explore the effects the central cyclopentanone ring. The electronic transi-
ofelectronicexcitationontheadsorptionofM1orM2 onthe tions are consistent with those expected for dibenzylide-
copper surface (Figure 2).
necyclopentanone compounds, exhibiting π → π* transi-
To provide molecular insights into the UV-Vis absorp- tion at a lower wavelength and n → π* at higher ones.
tion of these compounds, we performed an investigation
based on the TDDFT method. The plots of computational
data are presented in Figure 3. The computed UV-Vis
spectra show similarities with the experimental one.
The isosurface plots for the natural transition orbitals
3.3 Rotation energy barrier
(
NTOs), involved in the electronic transition responsible The dihedral scan from 0 to 360 degree using a 15-degree
for the UV-Vis absorptions, are depicted in Figure 3 step scan for both the molecules in the gas phase is
Figure 2: UV-Vis spectra of M1 (top left) and M2 (bottom left) in acetonitrile. Plots for determination of the extinction coefficients for M1 (top
right) and M2 (bottom right).

Corrosion study of copper in aqueous sulfuric acid solution in the presence of M1 and M2

1417
Figure 3: Calculated UV-Vis spectra of M1 (top left) and M2 (bottom left) in acetonitrile. Frontier molecular orbitals relevant for the electronic
transition and the corresponding energy differences – M1 (top right) and M2 (bottom right).
presented in Figure 4. The required energy for complete 3.5 MD
rotation is 48.39 kcal/mol for M1 and 52.91 kcal/mol for M2.
The rotation barrier of the molecules is in the same Intending to recognize the interaction details of the stu-
range as the stilbene molecules (48.3 kcal/mol).
died inhibitor with the Cu(110) surface at the molecular
level, the MD simulations were performed. The most
stable geometry configurations (Figure 6), together with
the RDF poses (Figure 7) acquired from these
3
.4 MC calculations
Figure 5 shows the distribution of the adsorption energies
during the MC calculations for the species used to simulate
the corrosion media. Being dependent on configuration of
inhibitor onto the Cu surface for M1 molecule, adsorption
energy shows the results within the range of −25.44 to
−45.45 kcal/mol, whereas the adsorption energy for the
M2 is in the range of −88.55 to −117.75 kcal/mol. The nega-
tive energy values are an indication of spontaneity of the
inhibitor adsorption toward the copper surface.
These rather high adsorption energy values are con-
sidered to be responsible for the water displacement from
the Cu(111) surface caused by the interaction of the inhi-
bitor by electron sharing of their oxygen (M1 and M2) and
nitrogen (for M2) and the surface. This involves the
overlap between the sharing of electrons from –O and
–
N atoms of the inhibitor and the 3d electrons of the
Figure 4: Calculated rotational energy barrier (gas phase) for M1
(black trace) and M2 (red trace).
copper surface [37].

1
418

Veprim Thaçi et al.
Figure 7: RDF of O and N atoms of M1 and M2 inhibitor molecules on
the Cu(111) surface.
Figure 5: Probability of adsorption energy distribution curves for Cu
(
(
111)/M1 or M2 + 200 water molecules/one inhibitor molecule
either M1 or M2 molecule)/25 ethanol molecules and 60 hydronium
+
30 sulfate-simulated corrosion media obtained via MC
that the bond length of O atoms and the copper surface
is less than 3.5 Å, directing to chemisorption of the inhi-
bitors. This strong interaction causes metal protection
against dissolution – through a chemisorption process.
calculations.
simulations, delivered an in-depth data concerning the
corrosion inhibition expressed by these two molecules.
Both the studied inhibitors are flat lying onto the
copper surface, and the higher value of adsorption en-
ergy (from MC) in the case of M2 compared to M1 is due to
a greater surface and the presence of two additional
nitrogen atoms of the former one.
3.6 Adsorption and corrosion inhibition
mechanism of M1 and M2 inhibitors
The RDF is often used in MD simulations to assess the The inhibition performance of an inhibitor is related to its
interaction type between the studied inhibitors and the adsorption ability on the interface of the metal. This ad-
surface. When the peaks reach the distances from 1 Å up sorptive interaction led to the formation of a protective
to 3.5 Å, it is considered as a sign associated normally layer onto the metal surface that protects the metal from
with the chemisorption (for the physisorption the peaks corrosion [40] From the obtained experimental and the-
start at the distances bigger than 3.5 Å) [38]. The RDF oretical results, the following adsorption mechanism is
value (Figure 7) for O atom of both molecules shows proposed (Figure 8).
Figure 6: Views of the most stable adsorption configuration for Cu (111)/(a) M1 or (b) M2 (b)/25 ethanol molecules and 60 hydronium + 30
sulfate-simulated corrosion media obtained via MD simulations.

Corrosion study of copper in aqueous sulfuric acid solution in the presence of M1 and M2

1419
(
in 4-dimethylamino group). These nitrogen atoms in-
crease the adsorption ability of this molecule as found
from theoretical calculations.
Acknowledgments: The authors gratefully acknowledge
the support from the Ministry of Education, Science and
Technology of Kosovo (No. 2-5069) for providing him
with the computing resources.
Conflict of interest: The authors declare no conflict of
interest.
References
Figure 8: The proposed adsorption mechanism of the M2 inhibitor
on the copper surface.
[
1] Schutze M, Feser R, Bender R. Corrosion resistance of copper
and copper alloys. Morlenbach. Germany: Wiley-VCH; 2011.
2] Zhou P, Ogle K, Wandelt K. The corrosion of copper and copper
alloys. In Encyclopedia of Interfacial Chemistry. Oxford, UK:
Elsevier; 2018. p. 478–89.
[
Monocurcumin molecules were chemically adsorbed onto
the Cu surface by donor/acceptor interaction between free [3] Telegdi J, Shaban A, Kálmán E. EQCM study of copper and iron
electron pairs of heteroatoms (oxygen for M1; oxygen and
nitrogen for the M2) and the vacant d-orbital of the copper
surface [39]. A crucial role for the adsorptive interaction is
also the donor/acceptor interaction between the anti-
bonding molecular orbitals of curcumin inhibitors and
the d-orbitals of the copper atoms of the surface [40].
corrosion inhibition in presence of organic inhibitors and
biocides. Electrochim Acta. 2000;45(22–23):3639–47.
4] Antonijević MM, Petrović MB. Copper corrosion inhibitors.
A Review. Int J Electrochem Sci. 2008;3:1–28.
5] Raja PB, Ismail M, Ghoreishiamiri S, Mirza J, Ismail M,
Kakooei S, et al. Reviews on corrosion inhibitors: A short view.
Chem En Commun. 2012;203:1145–56.
[
[
[6] Petrović Mihajlović MB, Antonijević MM. Copper corrosion in-
hibitors. Period 2008–2014. A Review. Int J Electrochem Sci.
2015;10:1027–53.
[
7] Fateh A, Aliofkhazraei M, Rezvanian AR. Review of corrosive
environments for copper and its corrosion inhibitors. Arab J
Chem. 2020;13:481–544.
4
Conclusions
[
[
[
8] Walker R. Triazole, benzotriazole and naphthotriazole as cor-
rosion inhibitors for copper. Corros. 1975;31:97–100.
9] Finšgar M, Milošev I. Inhibition of copper corrosion by 1,2,3-
benzotriazole: A review. Corros Sci. 2010;52:2737–49.
10] Cantwell MG, Sullivan JC, Burgess RM, Zeng EY. Chapter 16-
benzotriazoles: History, environmental distribution, and
potential ecological effects. In Comprehensive Analytical
Chemistry. Elsevier; 2015. p. 513–45.
The corrosion behavior of copper in 0.1 M aqueous sul-
furic acid medium was investigated using potentiody-
namic polarization measurements, quantum chemical cal-
culations, and MD simulations in the presence and absence
of (2E,5E)-2,5-dibenzylidenecyclopentanone (M1) and (2E,
5
E)-bis[(4-dimethylamino)benzylidene]cyclopentanone
[
11] Berisha A, Podvorica F, Mehmeti V, Syla F, Vataj D. Theoretical
and experimental studies of the corrosion behavior of some
thiazole derivatives toward mild steel in sulfuric acid media.
Maced J Chem Chem En. 2015;34:287–94.
(
M2). The main electronic transitions in the studied com-
pound as supported by TDFT calculations π → π* transi-
tion at a lower wavelength and n → π* at higher ones. MD
results show that these molecules are flat adsorbed onto
the copper surface. Selecting suitable substituents on the
dibenzylidenecyclopentanone system as shown here led
to different corrosion inhibition performance. In our on-
going studies, we have been exploring these effects. The
more pronounced corrosion inhibition performance of the
M2 derivative in comparison to M1 was related to the fact
that this molecule contains two basic nitrogen atoms
[
12] Mohsenifar F, Jafari H, Sayin K. Investigation of thermo-
dynamic parameters for steel corrosion in acidic solution in
the presence of N,N-bis(phloroacetophenone)-1,2-propanedi-
amine. J Bio Tribo Corros. 2016;2:1–13.
[
13] Popoola LT. Organic green corrosion inhibitors (OGCIs): A
critical review. Corros Rev. 2019;37(2):71–102.
[
14] Rani BEA, Basu BBJ. Green inhibitors for corrosion protection
of metals and alloys: An overview. 2012;15:380217. doi:
10.1155/2012/380217

1
420

Veprim Thaçi et al.
[
15] Mo Sh LiLJ, Luo HQ, Li NB. An example of green copper cor-
rosion inhibitors derived from flavor and medicine: vanillin
and isoniazid. J Mol Liq. 2017;242:822–30.
[27] Geerlings P, DeProft F, Langenaeker W. Conceptual density
functional theory. Chem Rev. 2003;103:1793–874.
[28] Gece G. The use of quantum chemical methods in corrosion
inhibitor studies. Corros Sci. 2008;50:2981–92.
[29] Obot IB, Macdonald DD, Gasem ZM. Density functional theory
(DFT) as a powerful tool for designing new organic corrosion
inhibitors. Part 1: An overview. Corros Sci. 2015;99:1–30.
[30] Hadzi-Petrushev N, Bogdanov J, Krajoska J, Ilievska J,
Bogdanova-Popov B, Gjorgievska E, et al. Comparative study
of the antioxidant properties of monocarbonyl curcumin
[
16] Tan J, Guo L, Yang H, Zhangc F, Bakri YE. Synergistic effect of
potassium iodide and sodium dodecyl sulfonate on the cor-
rosion inhibition of carbon steel in HCl medium: a combined
experimental and theoretical investigation. RSC Adv.
2
020;10:15163–70.
[
17] About S, Zouarhi M, Chebabe D, Damej M, Berisha A. Najat
Hajjaji. Galactomannan as a new bio-sourced corrosion inhi-
bitor for iron in acidic media. Helyon. 2020;6:03574.
2
analogues C66 and B BrBC in isoproteranol induced cardiac
[
18] Rbaa M, Dohare P, Berisha A, Dagdag O, Lakhrissi L, Galai M,
et al. New epoxy sugar based glucose derivatives as eco
friendly corrosion inhibitors for the carbon steel in 1.0 M HCl:
Experimental and theoretical investigations. J Alloy Compd.
damage. Life Sci. 2018;197:10–8.
[31] Neese F. The ORCA Program System. WIREs Comput Mol Sci.
2012;2:73–8.
[32] Neese F. Software Update: the ORCA Program System, version
4.0. WIREs Comput Mol Sci. 2018;8:e1327.
2
020;833:154949.
[
[
[
[
19] Souza FS, Giacomelli C, Gonçalves RS, Spinellia A. Adsorption [33] Akkermans RLC, Spenley NA, Robertson SH. Monte Carlo
behavior of caffeine as a green corrosion inhibitor for copper.
Mater Sci Eng C. 2012;32(8):2436–44.
methods in materials studio. Mol Simulat. 2013;39:
1153–64.
20] Zhao C, Liu Z, Liang G. Promising curcumin-based drug design: [34] Mehmeti VV, Berisha AR. Corrosion study of mild steel in
Mono-carbonyl analogues of curcumin (MACs). Cur Pharm Des.
013;19:2114–2135.
aqueous sulfuric acid solution using 4-methyl-4H-1,2,4-tria-
zole-3-thiol and 2-mercaptonicotinic acid – an experimental
and theoretical study. Front Chem. 2017;5:61. doi: 10.3389/
fchem.2017.00061.
2
21] Shetty D, Kim JY, Shim H, Snyder PJ. Eliminating the heart from
the curcumin molecule: Monocarbonyl curcumin mimics
(
MACs). Molecules. 2015;20:249–92.
[35] Sun H, Jin Z, Yang C, Akkermans RLC, Robertson SH,
Spenley NA, et al. COMPASS II: extended coverage for polymer
and drug-like molecule databases. J Mol Model.
2016;22(2):47.
[36] Lemak AS, Balabaev NK. On the Berendsen Thermostat. Mol
Simul. 1994;13:177–87.
22] Vatsadze SZ, Gavrilova GV, Zyuz’kevich FS, Nuriev VN,
Krut’ko DP, Moiseeva AA, et al. Synthesis, structure, electro-
chemistry, and photophysics of 2,5-dibenzylidenecyclopenta-
nones containing in benzene rings substituents different in
polarity. Russ Chem Bull. 2016;65:1761–72.
[
23] Zakharova GV, Zyuz’kevich FS, Gutrov VN, Gavrilova GV,
Nuriev VN, Vatsadze SZ, et al. Effect of substituents on spec-
tral, luminescent and time-resolved characteristics of 2,5-
diarylidene derivatives of cyclopentanone. High Energy Chem.
[37] Hsissou R, Abbout S, Berisha A, Berradi M, Assouag M,
Hajjaji N, et al. Experimental, DFT and molecular dynamics
simulation on the inhibition performance of the DGDCBA epoxy
polymer against the corrosion of the E24 carbon steel in 1.0 M
HCl solution. J Mol Struct. 2019;1182:340–51.
2
017;51:113–7.
[
[
[
24] Li Z, Pucher N, Cicha K, Torgersen J, Ligon SC, Ajami A, et al.
A straightforward synthesis and structure-activity relationship
of highly efficient initiators for two-photon polymerization.
Macromolecules. 2013;46:352–61.
[38] Tan J, Guo L, Lv T, Zhang S. Experimental and computational
evaluation of 3-indolebutyric acid as a corrosion inhibitor for
mild steel in sulfuric acid solution. Int J Electrochem Sci.
2015;10:823–87.
25] Carapina da Silva C, Pacheco BS, das Neves RN, Dié Alves MS, [39] Berisha A. Experimental, Monte Carlo and molecular dynamic
Sena-Lopes A, Moura S, et al. Antiparasitic activity of synthetic
curcumin monocarbonyl analogues against Trichomonas
vaginalis. Biomed Pharmacother. 2019;111:367–77.
study on corrosion inhibition of mild steel by pyridine deri-
vatives in aqueous perchloric acid. Electrochem.
2020;1(2):188–99.
26] Leow P-C, Bahety P, Boon CP, Lee CY, Tan KL, Yang T, et al.
Functionalized curcumin analogs as potent modulators of the
Wnt/beta-catenin signaling pathway. Eur J Med Chem.
[40] Lgaz H, Bhat KS, Salghi R, Jodeh S, Shubhalaxmi, Algarra M,
et al. Insights into corrosion inhibition behavior of three
chalcone derivatives for mild steel in hydrochloric acid solu-
tion. J Mol Liq. 2017;238:71–83.
2
014;71:67–80.