Alrasheedi et al. BMC Chemistry(2024) 18:128
https://doi.org/10.1186/s13065-024-01236-w

BMC Chemistry

RESEARCH

Open AccessCorrosion resistance of aluminum againstacid activation in 1.0 M HCl by symmetricalball − type zinc phthalocyanine
Najah F. H. Alrasheedi1,2, Ismail Abdulazeez3, Shamsuddeen A. Haladu4, Mohammed A. Gondal5,6, Khaled M. AlAqad7,
Salwa J. Kamal1, Salha N. Alharthi1 and Asma M. Elsharif1*
Abstract
The inhibition effect of symmetrical Ball − type Zinc Phthalocyanine on Aluminum in 1mol/L hydrochloric acidwas analyzed by electrochemical techniques. A novel ball-type zinc phthalocyanine (Zn-Pc) inhibitor has beensynthesized and verified utilizing FTIR, nuclear magnetic resonance (1H NMR and 13C NMR), MALDI-TOF MS, andabsorption spectroscopy (UV-Vis). In addition, laser-induced breakdown and photoluminescence spectroscopy
were employed for additional study. Weight loss technique was employed to investigate the corrosion inhibition
effectiveness of the synthesized Zn-Pc on Aluminum in 1mol/L hydrochloric acid at the range of variation
temperatures (293–333 K). The inhibition efficiency of Zn-Pc increased with higher concentrations of Zn-Pc anddecreased as the temperature increased. Furthermore, Zn-Pc demonstrated outstanding outcomes, achieving 72.9%
at a very low inhibitor concentration (0.4 mmol/L) at 298 K. The experimental data for Zn-Pc Aluminum in 1mol/Lhydrochloric acid obeys the Langmuir adsorption isotherm. Moreover, the corrosion system’s thermodynamic
parameters and activation energy were determined. Quantum chemical calculations applying the (DFT) Density
Functional Theory method was conducted and applied in this study. These calculations played a pivotal rolein elucidating molecular structures and reactivity patterns. Through DFT, numerous reactivity indicators werecomputed, providing valuable insights into the chemical behavior of the studied compounds. These indicators,
such as frontier molecular orbitals, electron density, and molecular electrostatic potential, were subsequently
correlated with experimental data.
Keywords Ball type, Zinc phthalocyanine, Corrosion resistance, Aluminium, Adsorption consideration, DFT*Correspondence:
Asma M. Elsharif
aelsharif@iau.edu.sa
1
Department of Chemistry, College of Science, Imam Abdulrahman Bin
Faisal University, P. O. Box 1982, Dammam 31441, Saudi Arabia
2
Department of Chemistry, College of Science and Arts, Qassim
University, Ar Rass 51921, Saudi Arabia
3
Interdisciplinary Research Center for Membranes and Water Security,
King Fahd University of Petroleum and Minerals, Dhahran
31261, Saudi Arabia

4

Department of Basic Engineering Sciences, College of Engineering,
Imam Abdulrahman Bin Faisal University, P. O. Box 1982, Dammam
31451, Saudi Arabia
5
Laser Research Group, Physics Department, King Fahd University ofPetroleum & Minerals (KFUPM), Mailbox 5047, Dhahran
31261, Saudi Arabia
6
K.A.CARE Energy Research & Innovation Center, King Fahd University ofPetroleum and Minerals, Dhahran 31261, Saudi Arabia
7
Applied Research Center for Environmental and Marine Studies, King
Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use,sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) andthe source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in thisarticle are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not includedin the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you willneed to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The
Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available
in this article, unless otherwise stated in a credit line to the data.

Alrasheedi et al. BMC Chemistry(2024) 18:128

Introduction
Phthalocyanines (Pcs) have caught the attention ofresearchers because of their numerous commercial andtechnical uses as colorants [1], chemical detectors [2–4],
sensitizers for photodynamic treatment [5], nonlinear optical substrate and recording devices [6, 7], solar
energy [8], catalysts [9], and elements of electricity -producing equipment [10–12]. Although the original molecules exhibit a variety of valuable qualities, significant
effort has been spent on developing novel structures that
may exhibit better or innovative properties [13]. Theircharacteristics can potentially be modified by selecting
insert metals and substituents with varying electricaland steric features [14]. Ball-type Pcs are unique, having been discovered by Tomilova’s group in the year 2002
[15, 16]. The newly developed form of Pcs includes fourbridging substituents on the periphery of the two cofacially positioned benzene rings that are part of the two
Pc monomers [17]. The linker components, which varysignificantly from their parent monomers, determine thelength across these two Pc rings as well as their chemicaland physical characteristics [16, 17]. In this type of combination, an intense connection between the upper face
and the down face of Pc rings or the two metal centers
has affected the spectroscopic and electrochemical studies [18]. Corrosive damage to metal is a serious economic
concern that has prompted several studies in recent years[19–21]. Corrosion is an irreversible interfacial reaction
between a substance (metal, material made of ceramics,
or polymer) and its environment, resulting in material
loss [22]. Corrosion’s negative impacts appear as machine
failures, financial expenditures associated with damage repairs, and contaminants to the environment [23].
Small substance materials, such as benzothiazoles, were
employed to prevent rusting [24, 25]. However, there is aneed for Large π-conjugated molecules, such as phthalocyanines, to offer superior corrosion resistance [26]. Pcs
have planar π-conjugated conformations that improvetheir capacity to adsorb onto metal surfaces, due to this;they have been used for corrosion prevention [27]. Moreover, phthalocyanines feature electron-rich sites suchas azomethine nitrogen atoms which can be employed
to separate metal surfaces from acidic environments byadsorption [28]. Considering the preparatory steps outlined above, we proceeded to synthesize a novel ball-typeinhibitor and subsequently embarked on an investigation.
Experimental
Materials and methods

The chemicals and solvents utilized in this research are ofanalytical quality and were used exactly as supplied into
its corrosion inhibition properties when applied to thealuminum samples.

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The aluminum specimen, composed of 98.5% pure aluminum, underwent precision cutting to produce pieces
with specific dimensions. These meticulously crafted segments measured 5 centimeters in length, 2 centimeters
in width, and 0.04 centimeters in thickness. This careful
preparation of the aluminum material ensured uniformity and accuracy in the experimental procedures. The
chemicals are Zinc acetate, 3-Nitrophthalonitrile, 4,4Biphenol, anhydrous Potassium carbonate, Dimethyl
Sulfoxide, methanol, and acetic acid were purchasedfrom Sigma Aldrich.

Synthesis
Synthesis of compound (3)A mixture of (1) 3-nitrophthalonitrile (0.6497 g 3.7mmol)and (2) 4,4′-Dihydroxybiphenyl (0.604 g 3.2mmol) in
dry dimethyl sulfoxide 20 ml was stirred at room temperature under Ar. Then K2CO3 (0.9042 g 6.54mmol)
was added to the mixture over a period of 2 h [29]. After
72 h of stirring, the mixture was heated for 2 h at 40 °C as
shown in Scheme 1. The following step was pouring into(100 ml) of cold water. The resulting solid was filtered
off and washed a couple of times with water and ethanol. The final step was using column chromatography toseparate the target compound using chloroform/acetone
9:1 (0.1637 g 0.22807mmol). FT-IR (KBr): 3100 (Ar-CH),
2235 (CN), 1590/1500 (C = C), and 1290/1180 (C-O-C).
1
H NMR (500 MHz DMSO-d6) δ, (ppm) = 7.73 (d, 4 H),
7.4 (dd, 2 H), 7.82 (d, 2 H), 7.86 (d,4 H), 7,88 (t,2 H). 13C
NMR (50 MHz, DMSO-d6) δ, (ppm): 105.90, 113.87,
116.12, 116.41, 120.86, 122.92, 128.94, 129.29, 136.57.,
137.02, 154.36, 160.11. M.p. 289 °C.
Synthesis of ball-type zinc phthalocyanine (4)Compound (3) (0.312 g 0.1566 mmol) and zinc (II) acetate (0.03 g 0.1626 mmol) were heated gradually in asealed glass tube for 3 h and 30 min under Argon atmosphere at 290 °C as shown in Scheme 1. After the compound cooled down to room temperature, the green
solid was washed with hot water and hot methanol. The
target product was dissolved in acetic acid, filtered, anddried. Yield: 0.1406 g (0.074607mmol). UV–Vis (DMSO),
λmax (nm): 697, and 322. FT-IR (ATR) (µmax/cm− 1): 3067
(Ar-CH),1723 (CO), 1474 (C = O), and 1266/1244/1163(C-O-C).1H NMR (500 MHz DMSO-d6) δ, (ppm) = 6.90-8(Ar-H). M.p. >386 °C. MS (MALDI-TOF), m/z
calcd.1883.31, founded 1894.

Apparatus
The chemical structures of all synthesized compounds
were confirmed by using (FTIR), (H1, 13C 500 MHz
NMR), a Bruker Auto flex MALDI-TOF MS, A fourthharmonic (266 nm), high energy Q-switched NdYAG (model: QUV-266-5) Laser-induced breakdownAlrasheedi et al. BMC Chemistry(2024) 18:128

Page 3 of 16

Scheme 1 Synthesis of the symmetrical ball − type zinc phthalocyanine

spectroscopy,
spectroscopy.

andFP-8500

photoluminescence

Corrosion measurements
Specimens and solutions

To prepare the aluminum samples for experimentation, athorough polishing process was employed using various
grades of emery papers. This procedure ensured that thesurface of each sample was smooth and free from imperfections. Following the polishing step, the samples were
meticulously cleaned by sequentially washing them withacetone to remove any residual contaminants, followedby distilled water to ensure purity. After this rigorous
cleaning regimen, the aluminum samples were carefully
dried, leaving them in an optimal state for subsequent
analyses and investigations. The corrosive medium is
1 mol/L hydrochloric acid, which was obtained by diluting concentrated (37%) hydrochloric acid supplied by
Fisher Scientific Company, using distilled water.
Gravimetric measurements

The pre-polished aluminium coupons were used as supplied and freely suspended in glass bottles containing
50 mL of HCl solution (1 M) in the absence and present

different amounts of Zn-Pc. After definite times, the aluminum coupons were withdrawn from the test solution
and dipped in fresh 1 M HCl solution to dislodge thecorroded residues. This was continued by thoroughly
cleaning with distilled water, acetone, and drying witha heat gun. The mass difference of the aluminum coupons before immersion in 1 M HCl and after is used asweight loss. The inhibition efficiency (IE), and corrosion
rate (mmpy) were computed according to Eqs. 1 and 2
respectively:

IE% =Wblank − Winh× 100 (1)WblankCR (mmpy ) =87.6 × W
(2)Atrwhere Wblank and Winh stand for the respective average
weight losses (mg) of aluminum coupons in pure 1 M
HCl and in the presence of Zn-Pc, A stands for the surface area (cm2), t is immersion time and r is aluminum
density (g/cm− 3).

Alrasheedi et al. BMC Chemistry(2024) 18:128

Surface characterization

A comprehensive examination of the surface morphology of aluminum coupons immersed in hydrochloric
acid (1.0 M), both with and without a novel zinc balltype Phthalocyanine was conducted. To achieve this,
we employed a scanning electron microscope (SEM)
to meticulously compare and analyze the surface characteristics. Prior to SEM analysis, we performed gravimetric experiments to assess any changes in mass dueto the interactions. Subsequently, the samples underwent a thorough cleansing process involving acetone andwater, followed by gentle drying at room temperature toensure the removal of any residual contaminants. Furthermore, (EDS) Energy Dispersive X-ray Spectroscopy
was employed to identify and quantify various components present on the aluminum surface to gain insight
into the chemical composition of the examined surfaces.
This comprehensive approach sheds light on the intricate
alterations occurring on the aluminum surface under the
influence of the ball-type zinc phthalocyanine and provides valuable data for further research in materials science and corrosion studies.
Laser-induced breakdown measurements

In the LIBS system, a fourth harmonic (266 nm), highenergy Q-switched Nd-YAG pulsed Laser (model: QUV266-5) with an output pulse duration of 8 ns, repetition
rate of 20 Hz, and maximum energy up to 50 mJ was
employed. The beam was collimated and focused on thesample by a UV convex lens with a focal length of 30 nm,
and the plasma was collected by an optical fiber supported by a small lens and connected to a 500 mm spectrograph (Andor SR 500i A). To avoid the formation of adeep crust during the LIBS analysis, the sample was continually moved on an X-Y transational stage. The detecting system (ICCD, model iStar 320 T, 690 × 255 pixels)
should be configured as follows: As reported in a previous paper, a total of 25 accumulations and a gate width of
2 s were chosen and used for all the recorded LIBS configurations [30].
Theoretical calculations

Structural models of the symmetrical ball-type zincphthalocyanine (Zn-Pc) were built using the Gauss View
5.0 GUI [31] and geometrically optimized using theGaussian 16 modeling suite [32]. The quantum mechanical density functional theory (DFT) method was usedat the hybrid B3LYP functional, and the Pople’s 6-31G*
and the Stuttgart-Dresden (SDD) effective core potential (ECP) basis sets for the non-metals (C, H, N, O) andthe metal (Zn) atoms, respectively. These basis sets have
proven to be very effective in predicting molecular geometries, structural interactions, and yield valid estimationsof solvation energies in simulations involving implicit

Page 4 of 16

solvent models. Moreover, they yield results with good
agreement with experimental findings [33–35], at a notably more modest computational cost [36, 37]. The structure was fully optimized to the minima on the potential
energy surface without enforcing symmetry restrictions. The PCM-SCRF model of solvation was chosen asreported in our previous studies [38, 39], and the solvent
depicted as water. Acid media simulation was conductedby simply protonating the high electron density oxygen
atoms within the molecule and adjusting the charge tomatch the overall added protons to the system. Reactivity descriptors were estimated according to the Pearson’s
DFT-Koopman theorem derived from the energy of thehighest occupied molecular orbital (EHOMO) and the lowest un-occupied molecular orbital (ELUMO) [40]. These
include the HOMO-LUMO energy gap (ΔEg), electronegativity (χ), global hardness (η), and the dipole moment(µ).

Results and discussion
Confirmation of the structure of the prepared compound(3)

Phthalonitriles (1) are a common starting material
because they provide excellent yields of the desired Pc
complexes. 3-nitrophthalonitrile, a diphthalonitrile, wasutilized to create ball-type Pcs using previously described
simplified synthesis and purification procedures, as illustrated in Scheme 1. 3-nitrophthalonitrile and 4,4′-Dihydroxybiphenyl in dry DMSO were stirred at RT under Ar.
Then K2CO3 was added to the mixture as a base. After
stirring the mixture for 72 h, it was heated for 2 h at 40 °C.
After the workup, the resulting new compound was confirmed by FT-IR (Fig. 1) with KBr pellets. One piece ofevidence for the successful synthesis of compound (3) isthe band’s appearance (C-O-C) at 1290/1180 cm− 1. Also,
the disappearance of the (OH) peak. Ar (C = C) peaks
at 1590/1500 cm− 1. 1H NMR spectra were recorded in
DMSO-d6 confirming the desired compound’s aromatic
proton (Ar-H). 13C NMR shows twelve environments,
the unique peaks are Sp CN around 115, sp2 C = C around
130, sp3 C-C around 114, and C-Ar around 160.
Confirmation of the structure of symmetrical ballzincphthalocyanine (4)Ball-type (Zn-Pc) was obtained in low yield. Fouriertransform infrared (FTIR) (analysis was used to confirm
the Pc structure. (Fig. 2), Nuclear magnetic resonance(H1NMR) Uv–Vis, and Laser-induced breakdown spectroscopy. The IR spectra clearly exhibit the disappearanceof the distinctive C ≡ N stretch from the spectrum after
the conversion to Pc, confirming that metaled Pc wasformed. The 1H NMR spectra of zinc Pc in DMSO wasdifficult to interpret, but it verified the presence of aromatic protons in the aromatic area. The aromatic protons

Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 5 of 16

Fig. 1 FTIR (KBr) of compound (3)were detected at nearly 6.90-8ppm in the 1H NMR spectra of zinc Pc, which is attributable to the 4,4′-Dihydroxybiphenyl substitution in the ball-type complex.
Furthermore, the resulting peaks were quite broad, as is
typical of face-to-face complexes [41]. The MALDI-TOFMS spectra of compound (4) in positive ions and linear
mode was obtained. Analysis was carried out using a
Bruker Autoflex MALDI-TOF MS in Reflectron mode.
Samples were checked at different mass ranges but the
final data was acquired between 300 and 9500 Da. Laser
power was optimized according to observed ion intensities to ensure sufficient ion generation with minimal
analyte degradation. A MALDI-TOF-MS spectrum withexceptional resolution was obtained. The peak intensities
and isotopic mass distribution of the experimental results
were compared with the theoretically calculated intensities and isotopic mass distribution of this compound.

The theoretical calculation was found m/z:1883.31, anda peak was detected experimentally around 1894. It wasnoted that the findings of the experiments and the theories were in good agreement because the same peak is
not found in the blank (matrix + Ag salt) as shown below.
The inset is a zoomed view of the peak at m/z 1894.
Characterization of ultraviolet-visible light (UV–Vis) spectra

The Pcs have regular electronic emission spectra andincludes two significant absorption bands, (B band or
Soret) which is located in the UV range around 300–
400 nm and the other in the visible region around 600–
800 nm (Q band) due to the π → π* transition from themacrocyclic structure, the molar absorptivity frequently
exceeds 10− 5 L mol− 1 cm − 1. Ball-type Pcs’ electrical andother characteristics drastically rely on combination ofbridging compounds, solvents, and metals. The extent

Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 6 of 16

Fig. 2 FTIR of ball − type zinc phthalocyanine (4)of interaction is also affected by the bridging substituents and the length between two Pc dimers of the ballPcs. A slightly absorption band with a lower intensity (Qband) was observed in the spectra of ball (Zn-Pc) (Fig. 3)
at 697, which coincides with the π → π* transition fromthe (HOMO) which is highest occupied molecular orbitalto the (LUMO) lowest unoccupied molecular orbital.
Aggregation is demonstrated by decrease in the intensityand expansion of the Q bands, as well as the intensity of
the B bands of ball-type zinc phthalocyanine of ball-typezinc phthalocyanine. The electrical absorption spectra with the exception that the Q band at 697 nm is notdivided due to the existence of a higher energy shoulder
at 609 nm. This is consistent with coupling theory of theexcitation [42]. Because of deeper level of LUMO transition, zinc Pc exhibits high UV absorptions in the area (Bband) between 290 and 400 nm.

Characterization of photoluminescence

Photoluminescence (PL) is an effective probe for excitedstates because its features such as quantum yields, spectra, time frame decay, and temperature dependence canprovide useful information. The (PL) spectrum of thesymmetrical ball (Zn-Pc) was detected to investigate thephotogenerated charge transfer process since it is a convective approach to studying the photoinduced charge
separation behavior of the synthesized compound. The
luminescence characteristics of the materials were investigated by measuring their photoluminescence spectra in
the visible band from 200 to 800 nm (Fig. 4). The photoluminescence and corresponding excitation spectra
were obtained at room temperature using FP-8500 Fluorescence Spectrometer. The sample was excited with awavelength of 220 nm. The photoluminescence excitation spectra of prepared ball-type zinc phthalocyanine

Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 7 of 16

Fig. 3 Ultraviolet-visible light of zinc ball-type phthalocyanine (4)showed two shoulders of emission in the blue-green
region at 300 and 400 nm [43, 44]. The transition metal
influences the intensity of the spectrum. In phthalocyanines, a phenomenon known as diamagnetic quenchingoccurs, which reduces the intensity of the spectra. The
observed spectrum demonstrates that phthalocyanines
are photosensitive [45, 46].
Analysis of laser-induced breakdown measurements

The LIBS method was used to conduct a qualitative
investigation of ball-type phthalocyanine. LIBS is a technology that generates plasma light from a material byfocusing the radiation originating from a pulsator laserthat works at a set wavelength. The plasma composition is representative of the sample’s elemental content.
LIBS spectra were obtained by averaging 25 accumulations from at least three surface points. This was done tolimit the potential impact of sample heterogeneity andlaser pulse variations [36]. Also, this enhanced the LIBS

signal-to-noise ratio. The collected spectra revealed an
outstanding variety of spectral lines from an element,
allowing for the qualitative identification of components
contained in the ball-type zinc phthalocyanine sample’scharacterization plasma. Each element is pressed bya pattern of distinctive emission lines. Line identification using the NIST atomic spectral database revealed
the presence of the Zn element around 514 nm in a zincphthalocyanine sample (Fig. 5).
Weight loss measurements

The weight loss of the aluminium sample was determinedin the inhibited and uninhibited 1 M HCl solution for
24 h. The outcome of results (Table 1) indicates a rise on
the inhibition efficiency along with the rising in Zn-Pc
concentration, implying increased metal surface coverage by the compound thereby blanketing the aluminium
surface from the aggressive medium [47, 48]. The effectof temperature (293–333 K) was also investigated. The

Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 8 of 16

Fig. 4 Photoluminescence of zinc ball-type phthalocyanine (4)result (Table 1) revealed a decline in the inhibition efficiency as the temperature was elevated. This could be
ascribed to the diminishing of the electrostatic force of
attraction between the metal out layer and the inhibitor due to the increased kinetic energy of the inhibitor
and the result is an acceleration in the dissolution of themetal [49].
Adsorption consideration

It is assumed that the mechanism by which inhibitor
compound mitigates corrosion is by adsorption onto themetal surface, which in turn suppresses corrosion [50,51]. Considering this, adsorption isotherms are applied
to provide essential information about the process. Consequently, the widely obeyed Langmuir adsorption isotherm (Eq. 3) was employed.

Cinh
1
=
+ Cinh (3)θ
Kads
where Cinh, θ, and Kads represent inhibitor concentration(mmol/L), surface coverage (IE/100), and equilibrium
constant (mol/L), respectively. The obtained Langmuir
isotherm plot (Cinh/θ versus Cinh) shown in Fig. 6 is linearwith an R2 value of 0.999 at 293 K, which implies a goodcorrelation with the model. Afterward, the Kads value(7.86 × 104 mol/L) obtained from the reciprocal of theLangmuir plot’s intercept was implemented to computethe standard free energy of adsorption ∆Goads according
to Eq. 4.

∆Goads = −RTln (55.5Kd) (4)Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 9 of 16

Fig. 5 Laser-induced breakdown spectroscopy of zinc ball-type phthalocyanine (4)Table 1 Inhibition efficiency and corrosion rate data for aluminium in 1 M HCl with and without Zn-Pc at various temperatures
Concentration (mmol/L)
Blank
0.01
0.04
0.07
0.1
0.4

Inhibition efficiency (%)
298 K
313 K
48.7
29.3
50.7
31.7
68.9
32.5
69.4
34.4
72.9
35.4

The molar gas constant is R, whereas T is the absolutetemperature, and the concentration of the molar of 1 L
water is 55.5. The calculated ∆Goads measurement for
Zn-Pc is -37.24 kJ/mol. When the absolute value of ∆Goads
is high, the process of adsorption of Zn-Pc is expected to
be strong onto the metal surface. Generally, ∆Goads measurements that are roughly − 20 kJ/mol or lower negative are suggestive of physisorption, whereas − 40 kJ/mol
or more are suggestive of chemisorption. Accordingly,
the current inhibitor’s adsorption mechanism possibly

333 K
19.2
11.6
12.3
10.6
12.6

Corrosion rate (mmpy)
298 K
313 K
32.6
36.7
16.7
25.9
16.1
25.1
10.2
24.8
9.9
24.1
8.8
23.7

333 K
45.5
36.8
40.2
39.9
40.7
39.8

involves a comprehensive (physisorption and chemisorption) mechanism [52].
Furthermore, the activation energy for aluminium
corrosion was calculated using the Arrhenius equation(Eq. 5) in the presence and absence of Zn-Pc.

logCR = logA −




Ea
(5)
2.303RT

Alrasheedi et al. BMC Chemistry(2024) 18:128

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Fig. 6 Langmuir isotherm plot for Zn-Pc corrosion inhibition at 293 K on aluminum in 1 mol/L hydrochloric acid

Table 2 Activation and thermodynamic parameters for aluminium in 1 M HCl with and without Zn-Pc
Concentration (mM)
Blank
0.01
0.04
0.07
0.1
0.4

Ea (kJ mol− 1)
6.70
15.98
18.57
27.90
28.60
30.68

A
14.9
58.9
90.9
403.9
452.8
626.5

R2
0.959
0.999
0.997
0.981
0.988
0.980

where A is the exponential factor, R, T and CR as
described earlierLog CR Vs 1/T plots for both inhibited and uninhibited systems are linear, with R2 values approaching unity. The results presented in Table 2
revealed that the Ea is lower in solution that does notcontain inhibitor than in the presence of Zn-Pc andincreases as Zn-Pc concentration increases. This implies
that the inhibitor compound raises the activation barrier
thereby hampering the progress of the corrosion process.
The thermodynamic parameters ( ∆S* and ∆H* ) werealso calculated using transition state equation (Eq. 6).

DH*(kJ mol− 1)
4.11
13.39
15.98
25.30
26.01
28.09

CR
log
=
T



R
log
Nh

DS*(J mol− 1 K− 1)-201.96-175.62-167.3-138.75-136.56-130.35



+



∆S*
2.303T



−

R2
0.905
0.999
0.996
0.977
0.985
0.976

∆H*
(6)
2.303RT

In which N is Avogadro’s number, h is the value ofPlanck’s constant, and R, T, and CR are as previously
mentioned. By displaying Log CR/T as a function of
1/T (Fig. 7), a straight line was formed (Fig. 7), fromwhich ∆S* and ∆H* were computed from the intercept(Log(R/Nh) + ∆S* /2.303T) and slope (- ∆H* /2.303R),
respectively.
The data (Table 2) shows that the ∆H* values are positive and increased with increase in Zn-Pc concentration,
indicating the process to be endothermic and that theAlrasheedi et al. BMC Chemistry(2024) 18:128

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Fig. 7 Arrhenius (a) and Transition state (b) plots for the corrosive effect on aluminum in 1 M HCl with and without Zn-Pc (0.01–0.4 mmol/L)decline in the corrosion rate is assumed to be predominantly controlled by kinetic parameters [53]. On theother hand, the ∆S* values are negative and also increase
with increase in Zn-Pc concentration, implying that,upon the addition of Zn-Pc, the activation complex ismore ordered as the corrosion process progresses, whichis evident in the overall decrease in the corrosion rate
[54].

Fig. 8 SEM micrographs of aluminum surface on (a, d) freshly polished, (b, e) blank, and (c, f) in the presence of the Zn-Pc inhibitor, at different magnifications (20 and 50 μm) respectively

Alrasheedi et al. BMC Chemistry(2024) 18:128

Surface characterization

The results of (SEM) scanning electron microscopy
analysis revealed significant variation in the surface
morphology of the aluminum (Al) samples under various conditions. When the aluminium coupon was not
introduced to symmetrical ball Zinc Phthalocyanine, thesurface exhibited severe pitting and rectangular cavities,
indicative of extensive corrosion as shown in Fig. 8(b-e).
In contrast, the freshly polished surface showed no signsof pits or damage Fig. 9(a-d). However, when the symmetrical ball Zinc Phthalocyanine was added, the levelof damage was notably reduced, and a protective film
appeared on the surface, covering approximately 70%
Fig. 8(c-f ). This suggests that the effect of the symmetrical ball-type zinc phthalocyanine played a crucial role inmitigating corrosion and preserving the integrity of the
Al surface.
The (EDS) Energy Dispersive X-ray Spectroscopy
Analysis Fig. 9 conducted using the aluminum samples
yielded distinct elemental compositions when comparing
the absence and presence of the symmetrical ball Zn-Pc

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in 1 M HCl. In the absence of the symmetrical ball Zn-Pc,
the aluminum sample exhibited varying percentages of
elements, with 15.63% carbon, 2.42% nitrogen, 22.63%
oxygen, and 59.32% aluminum on the surface (Fig. 9a).
However, when the ball type Zinc Phthalocyanine wasintroduced, notable differences were observed (Fig. 9b).
The percentage of oxygen decreased to 2.19%, indicating a reduction in surface oxidation, while the aluminum
percentage significantly increased to 96.41%. This transformation in elemental composition suggests that thepresence of the symmetrical ball Zn-Pc had a significant
impact on altering the surface chemistry of the aluminum samples, reducing oxygen content and enhancing
aluminum concentration, which may have contributed tothe observed protective effects against corrosion.
Computational results

Insights into the corrosion inhibition potential of the isolated Zn-Pc and the protonated H+-Zn-Pc molecules inaqueous medium was investigated from DFT perspective. The optimized structural geometries, the HOMO,

Fig. 9 EDS spectrum of (a) Al specimen immersed in the absence of ball-type zinc phthalocyanine, (b) Al specimen immersed with presence of ball-typezinc phthalocyanine in 1 M HClAlrasheedi et al. BMC Chemistry(2024) 18:128

LUMO orbital distributions, and the electrostatic
potential (ESP) maps of both molecules are presented
in Fig. 10. Apparently, the HOMO-LUMO orbitals are
distributed across the aromatic units of the macrocyclic
iso-indole fragments and the nitrogen heteroatoms on
the Zn-Pc framework. This indicate the great potential of
the Zn-Pc ability to donate electron pairs to the vacantd-orbitals of aluminum ions and to accept back-donation
during molecular level interactions, in accordance withthe molecular orbital theory [55]. Moreover, the ESP
maps of the molecules indicate high electron density on
the bridging oxygen atoms, suggesting the regions likely
to undergo charge donation to the aluminum surface
ions. ESP is graphical representation of the charge distribution on the surface of a molecule. It is often characterized by regions in red, which indicates centers ofabundant electrons, blue regions, which implies electrondeficient centers, and neutral centers depicted as green.
Others are the greenish-blue regions which represent theslightly electron-deficient centers, and the yellow regions
which indicate the slightly electron-rich centers.
Meanwhile, the electronic properties of the molecules(Fig. 11) vis-à-vis the HOMO-LUMO energy gap (ΔEg),
the electronegativity (χ) which represent the electron
attraction potential of the molecules, the global hardness (η) which depicts the resistance of the molecules
to electron density distortions during interactions, andthe dipole moment (µ) which represent the electronic
charge separation within the molecules further indicatethat while no significant distortion in electronic properties were observed on the molecules of H+-Zn-Pc after
protonation, the dipole moment exhibit a 3-fold increase

Page 13 of 16

suggesting stronger electrostatic attractions to the metallic surface. This consequently implies stronger adsorption and corrosion protection to aluminum surface in theavailability of the Zn-Pc in acidic medium, as evidenced
in the experimental results.

Conclusion
Symmetrical Ball − type Zinc Phthalocyanine was synthesized without using a solvent, which was done in anenvironmentally friendly way. The synthesis compound
exhibited noticeable co-facial intramolecular interactionsof the Pc-macrocycles in their UV/Vis spectra in solution.
Additionally, this approach allows for the variation of thezinc metal, and non-peripheral substitution pattern totune the dimer’s characteristics. The corrosion-inhibition
behavior of the synthesized symmetrical ball Zn-Pc on
Aluminum in 1 mol/L hydrochloric acid at the range ofvariation temperatures (293–333 K) was investigated byweight loss technique. The ability of symmetrical ball
Zn-Pc to effectively prevent the corrosion of aluminum in
1.0 M hydrochloric acid was shown to increase as Zn-Pc
concentration increased, however, it decreased as temperature increased. In addition, Zn-Pc displayed exceptional outcomes, accomplishing 72.9% at an extremely
small inhibitor concentration (0.4 mmol/L) at 298 K. The
estimated ∆Goads measurement for Zn-Pc is -37.24 kJ/
mol, indicating that the present inhibitor’s adsorption
mechanism is likely to involve both physisorption andchemisorption. Density Functional Theory (DFT) calculations were meticulously performed on zinc ball-typephthalocyanine as a fundamental step in comprehending
the intricate electronic properties crucial for designing

Fig. 10 The optimized structural geometry, HOMO-LUMO frontier orbital distribution, and the electrostatic potential (ESP) map of (a) Zn-Pc, and (b) H+Zn-Pc in aqueous medium

Alrasheedi et al. BMC Chemistry(2024) 18:128

Page 14 of 16

Fig. 11 The electronic properties of Zn-Pc and H+-Zn-Pc in aqueous medium at the B3LYP/6-31G* & SDD levels of theory

an effective inhibitor against aluminum corrosion. By utilizing DFT, we delved into the quantum-level details of
the compound’s electronic structure, investigating factors
such as electron distribution, energy levels, and molecular interactions. This in-depth analysis allowed us to gain
valuable insights into how specific electronic characteristics influence the inhibition process, paving the way forthe informed design of corrosion inhibitors tailored toprotect aluminum against deterioration.

Supplementary Information

The online version contains supplementary material available at https://doi.
org/10.1186/s13065-024-01236-w.
Supplementary Material 1
Acknowledgements
The authors would like to extend their sincere acknowledgment for the
support provided by College of Science and Basic and Applied ResearchCenter, Imam Abdulrahman Bin Faisal University and Qassim University, Saudi
Arabia.
Author contributions
Najah F.H. Alrasheedi: Methodology, Investigation, Visualization, Writing –original draft. Ismail Abdulazeez: Investigation, Formal analysis, Software,
Data curation, Visualization. Shamsuddeen A. Haladu: Formal analysis,
Investigation, Writing – review & editing. Mohammed A. Gondal: Formal

analysis, Investigation, Writing – review & editing. Khaled M. AlAqad:
Formal analysis, Software, Writing – review & editing. Salwa J. Kamal: Formal
analysis, Funding acquisition, Writing – review & editing. Salha N. Alharthi:
Formal analysis, Funding acquisition, Writing – review & editing. Asma M.
Elsharif: Methodology, Conceptualization, Writing – original and final draft,
Supervision, Funding acquisition.
Funding
Not applicable.
Data availability
The datasets supporting the conclusions of this article are included within thearticle and its additional files (Supplementary file, Figures and Tables).

Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Received: 23 March 2024 / Accepted: 27 June 2024

Alrasheedi et al. BMC Chemistry(2024) 18:128

References
1. Christie RM, Freer BG. Colour and constitution relationships in organic pigments: part 3-phthalocyanines. Dyes Pigm. 1994;24(2):113–24.
2. Özer M, Altındal A, Özkaya AR, Bekaroğlu O. Ball-type supramolecular metallophthalocyanines with eight perfluorodecyl units: chemosensors for SO2
and electrocatalysts for oxygen reduction. Dalton Trans. 2009;17:3175–81.
3. Açıkbaş Y, Evyapan M, Ceyhan T, Çapan R, Bekaroğlu O. Characterization andorganic vapor sensing properties of Langmuir-Blodgett film using a new
three oxygen-linked phthalocyanine incorporating lutetium. Sens Actuators
B. 2009;135(2):2009:426–9.
4. Ozoemena KI, Nyokong T. Novel amperometric glucose biosensor based onan ether-linked cobalt (II) phthalocyanine-cobalt (II) tetraphenylporphyrinpentamer as a redox mediator. Electrochim Acta. 2006;51(24):5131–6.
5. Nelson JS, Liaw LH, Orenstein A, Roberts WG, Berns MW. Mechanism oftumor destruction following photodynamic therapy with hematoporphyrin derivative, chlorin, and phthalocyanine. JNCI: J Natl Cancer Inst.
1988;80(20):1599–605.
6. Gu D, Chen Q, Tang, Gan F, Shen S, Liu K, Xu H. Application of phthalocyanine
thin films in optical recording. Opt Commun. 1995;121(4–6):125–9.
7. Yüksek M, Ceyhan T, Bağcı F, Yağlıoğlu HG, Elmali A, Bekaroğlu O. The nonlinear refraction and absorption dependence on the thermal effect for 4 ns
pulse duration in binuclear zn (II) phthalocyanine solution. Opt Commun.
2008;281(14):3897–901.
8. O’Regan BC, López-Duarte L, Martínez-Díaz MV, Forneli A, Albero J, Morandeira A, Durrant JR. Catalysis of recombination and its limitation on open
circuit voltage for dye sensitized photovoltaic cells using phthalocyanine
dyes. J Am Chem Soc. 2008;130(10):2906–7.
9. Koç I, Özer METIN, Özkaya AR, Bekaroğlu Ö. Electrocatalytic activity, methanol
tolerance and stability of perfluoroalkyl-substituted mononuclear, andball-type dinuclear cobalt phthalocyanines for oxygen reduction in acidic
medium. Dalton Trans. 2009;32:6368–76.
10. Kobayashi N, Kobayashi Y, Osa T. Optically active phthalocyanines and theircircular dichroism. J Am Chem Soc. 1993;115(23):10994–5.
11. Leznoff CC, Lever A. Properties and applications VCH New York; 1989.
12. McKeown NB. Phthalocyanine materials: synthesis, structure and function(No. 6). Cambridge University Press; 1998.
13. Ozoemena KI, Zhao Z, Nyokong T. Immobilized cobalt (II) phthalocyanine–
cobalt (II) porphyrin pentamer at a glassy carbon electrode: applications toefficient amperometric sensing of hydrogen peroxide in neutral and basic
media. Electrochem Commun. 2005;7(7):679–84.
14. Zhao Z, Ozoemena KI, Maree DM, Nyokong T. Synthesis and electrochemical
studies of a covalently linked cobalt (II) phthalocyanine–cobalt (II) porphyrin
conjugate. Dalton Trans 2005;(7):1241–8.
15. Tolbin AY, Ivanov AV, Tomilova LG, Zefirov NS. Preparation of 1, 2-bis (3, 4-dicyanophenoxymethyl) benzene and the binuclear zinc phthalocyanine derived
from it. Mendeleev Commun. 2002;12(3):96–7.
16. Tolbin AY, Ivanov AV, Tomilova LG, Zefirov NS. Synthesis of 1, 2-bis (3,4-dicyanophenoxymethyl) benzene and binuclear zinc phthalocyanines ofclamshell and ball types. J Porphyr Phthalocyanines. 2003;7(03):162–6.
17. Bekaroğlu Ö. Functional phthalocyanine molecular materials, Vol. 135.
Springer Science & Business Media; 2010.
18. Kakı E, Altındal A, Salih B, Bekaroğlu Ö. Synthesis, characterization and gas
sensing properties of novel homo and hetero dinuclear ball-type phthalocyanines. Dalton Trans. 2015;44(17):8293–9.
19. Atrens A, Song GL, Cao F, Shi Z, Bowen PK. Advances in mg corrosion andresearch suggestions. J Magnesium Alloys. 2013;1(3):177–200.
20. Frankel GS. Pitting corrosion of metals: a review of the critical factors. J Electrochem Soc. 1998;145(6):2186.
21. Dong J, Han E, Ke W. Introduction to atmospheric corrosion research in China.
Sci Technol Adv Mater. 2007;8(7–8):559–65.
22. Darvell BW. Materials science for dentistry. Woodhead publishing; 2018.
23. Roberge PR. Handbook of corrosion engineering. McGraw-Hill Education;
2019.
24. El-Rehim SA, Refaey SAM, Taha F, Saleh MB, Ahmed RA. Corrosion inhibitionof mild steel in acidic medium using 2-amino thiophenoland 2-cyanomethyl
benzothiazole. J Appl Electrochem. 2001;31:429–35.
25. Yadav M, Kumar S, Kumari N, Bahadur I, Ebenso EE. Experimental andtheoretical studies on corrosion inhibition effect of synthesized benzothiazole derivatives on mild steel in 15% HCl solution. Int J Electrochem Sci.
2015;10:602–24.
26. Dibetsoe M, Olasunkanmi LO, Fayemi OE, Yesudass S, Ramaganthan B, Bahadur I, Ebenso EE. Some phthalocyanine and naphthalocyanine derivatives asPage 15 of 16

27.
28.
29.
30.

31.
32.
33.
34.
35.

36.

37.

38.
39.
40.
41.
42.
43.

44.
45.

46.
47.
48.

corrosion inhibitors for aluminium in acidic medium: experimental, quantum
chemical calculations. QSAR studies and synergistic effect of iodide ions.
Molecules. 2015;20(9):15701–34.
Aoki IV, Guedes IC, Maranhão SLDA. Copper phthalocyanine as corrosion
inhibitor for ASTM A606-4 steel in 16% hydrochloric acid. J Appl Electrochem.
2002;32:915–9.
Chauhan DS, Verma C, Quraishi MA. Molecular structural aspects of organic
corrosion inhibitors: experimental and computational insights. J Mol Struct.
2021;1227:129374.
Keller TM. Phthalonitrile-based high temperature resin. J Polym Sci Part A:
Polym Chem. 1988;26(12):3199–212.
Alhasmi AM, Gondal MA, Nasr MM, Shafik S, Habibullah YB. Detection of toxic
elements using laser-induced breakdown spectroscopy in smokers’ andnonsmokers’ teeth and investigation of periodontal parameters. Appl Opt.
2015;54(24):7342–9.
Dennington RK, Millam J. GaussView, Version 5, Semichem Inc. Shawnee Mission: KS; 2009.
Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR et al.
Gaussian 16 Rev. C.01, Wallingford, CT; 2016.
Valadi FM, Shahsavari S, Akbarzadeh E, Gholami MR. Preparation of new
MOF-808/chitosan composite for cr (VI) adsorption from aqueous solution:
experimental and DFT study. Carbohydr Polym. 2022;288:119383.
Malhotra M, Puglia M, Kalluri A, Chowdhury D, Kumar CV. Adsorption of
metal ions on graphene sheet for applications in environmental sensing andwastewater treatment. Sens Actuators Rep. 2022;4:100077.
Mohan K, Purushothaman A, Janardanan D, Haridas KR. Experimental andtheoretical studies of azo derivatives in terms of different donors, acceptors and position isomerism: synthesis, characterization and a combined
electronic absorption, electrochemical and DFT study. J Mol Struct.
2022;1249:131621.
Abdulazeez I, Khaled M, Al-Saadi AA. Impact of electron-withdrawing
and electron-donating substituents on the corrosion inhibitive properties of benzimidazole derivatives: a quantum chemical study. J Mol Struct.
2019;1196:348–55.
Elsharif AM, Abdulazeez I, Almarzooq MA, Haladu SA. Synthesis, andexperimental evaluation of novel 4-(-3-(2-hydroxyethoxy)-3-oxopropenyl)1,2-phenylene nanohybrid derivatives as potential corrosion inhibitors for
mild steel in 1 M HCl. J Ind Eng Chem. 2022;116:474–88.
Nnadiekwe CC, Mustapha U, Abdulazeez I, Alhooshani K, Al-Saadi AA, Interfaces. Alkali metal ion-doped heptazine-based g-C3N4 quantum dots for
efficient adsorption of methyl blue. DFT Perspective. 2023;38:102852.
Umar M, Nnadiekwe CC, Abdulazeez I, Alhooshani K, Al-Saadi AA. Nitrogenenhanced charge transfer efficacy on the Carbon sheet: a theoretical insight
into the adsorption of Anionic Dyes. Arab J Sci Eng. 2022;47(1):419–27.
Pearson RG. Absolute electronegativity and hardness: application to inorganic chemistry. Inorg Chem. 1988;27(4):734–40.
Leznoff CC, Marcuccio SM, Greenberg S, Lever ABP, Tomer KB. Metallo phthalocyanine dimers incorporating five-atom covalent bridges. Can J Chem.
1985;63(3):623–31.
Şengül A, Doğan HZ, Altındal A, Özkaya AR, Salih B, Bekaroğlu Ö. Synthesis,
interface (Au/M 2 pc 2/p-Si), electrochemical and electrocatalytic properties
of novel ball-type phthalocyanines. Dalton Trans. 2012;41(25):7559–72.
Yu L, Zhang X, Zhuang C, Lin L, Li R, Peng T. Syntheses of asymmetric zincphthalocyanines as sensitizer of Pt-loaded graphitic carbon nitride for
efficient visible/near-IR-light-driven H2 production. Phys Chem Chem Phys.
2014;16(9):4106–14.
Bhattacharjee U, Men L, Rosales BA, Alvarado SR, Vela J, Petrich JW. Using
ATTO dyes to probe the photocatalytic activity of Au–CdS nanoparticles. J
Phys Chem 2017;C 121(1):676–83.
Gürel E, Pişkin M, Altun S, Odabaş Z, Durmuş M. Synthesis, characterization and investigation of the photophysical and photochemical propertiesof highly soluble novel metal-free, zinc (II), and indium (III) phthalocyanines substituted with 2, 3, 6-trimethylphenoxy moieties. Dalton Trans.
2015;44(13):6202–11.
Liu X, Zhang Q, Wu Z, Shi X, Zhao N, Qiao Y. Rapid elemental analysis andprovenance study of Blumea balsamifera DC using laser-induced breakdown
spectroscopy. Sensors. 2014;15(1):642–55.
Haladu SA, Umoren SA, Ali SA, Solomon MM. Synthesis and characterizationof cyclic cationic polymer and its anti-corrosion property for low carbon steel
in 15% HCl solution. Int J Electrochem Sci. 2017;12(10):9061–83.
Verma C, Olasunkanmi LO, Obot IB, Ebenso EE, Quraishi MA. 5-Arylpyrimido-[4,5-b] quinoline-diones as new and sustainable corrosion inhibitors forAlrasheedi et al. BMC Chemistry

49.

50.
51.
52.

(2024) 18:128

mild steel in 1 M HCl: a combined experimental and theoretical approach.
RSC Adv. 2016;6:15639–54.
Elsharif AM, Abubshait SA, Abdulazeez I, Abubshait HA. Synthesis, characterization and corrosion inhibition studies of polyunsaturated fatty acid derivatives on the acidic corrosion of mild steel: experimental and computational
studies. J Mol Liq. 2020;319:114162.
Umoren SA. Polypropylene glycol: a novel corrosion inhibitor for × 60 pipeline steel in 15% HCl solution. J Mol Liq. 2016;219:946–58.
Christov M, Popova A. Adsorption characteristics of corrosion inhibitors fromcorrosion rate measurements. Corros Sci. 2004;46:1613–20.
Kosari A, Moayed MH, Davoodi A, Parvizi R, Momeni M, Eshghi H, et al.
Electrochemical and quantum chemical assessment of two organic compounds from pyridine derivatives as corrosion inhibitors for mild steel in
HCl solution under stagnant condition and hydrodynamic flow. Corros Sci.
2014;78:138–50.

Page 16 of 16

53. Aljourani J, Raeissi K, Golozar MA. Benzimidazole and its derivatives as corrosion inhibitors for mild steel in 1 M HCl solution. Corros Sci. 2009;51:1836–43.
54. Elsharif AM, Abubshait SA, Abdulazeez I, Abubshait HA. Synthesis of a newclass of corrosion inhibitors derived from natural fatty acid: 13-Docosenoic acid amide derivatives for oil and gas industry. Arab J Chem.
2020;13:5363–76.
55. Gece G, Bilgiç S. Quantum chemical study of some cyclic nitrogencompounds as corrosion inhibitors of steel in NaCl media. Corros Sci.
2009;51(8):1876–8.

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