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Mack John


Ostatnie publikacje
1.  Nnaemeka N., Nwaji N., John M., Tebello N., Ball-type phthalocyanines and reduced graphene oxide nanoparticles as separate and combined corrosion inhibitors of aluminium in HCl, Journal of molecular structure, ISSN: 0022-2860, DOI: 10.1016/j.molstruc.2021.130279, Vol.1236, pp.1-12, 2021

Streszczenie:
Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were
investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4
-((4-(benzo[d]thiazol-2-yl)-
1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-
bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The
mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and
predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave
inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence
of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron
microscopy revealed effective metal surface protection by the inhibitors by formation of protective films

Afiliacje autorów:
Nnaemeka N. - inna afiliacja
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
2.  Shereen A. M., Nwaji N., John M., Tebello N., Saad M., Nonlinear optical responses of carbazole-substituted phthalocyanines conjugated to graphene quantum dots and in thin films, Journal of Luminescence, ISSN: 0022-2313, DOI: 10.1016/j.jlumin.2019.04.034, Vol.213, pp.88-97, 2019

Streszczenie:
hree different phthalocyanine complexes substituted with carbazoles were conjugated to graphene quantum dots (GQDs) through π–π stacking. The morphologies, sizes, and crystallinities of the nanoconjugates were determined using Raman spectroscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The nonlinear optical (NLO) properties of the metallophthalocyanines alone and when conjugated to the GQD nanomaterial in different solvents, as well as after having been embedded in thin films, were studied. The effects of the different substituents and solvents on the NLO properties of the metallophthalocyanines were evaluated. Enhancements in the photophysical properties of the complexes upon conjugation with the nanomaterial were observed. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields, and triplet lifetimes were measured for the complexes, and for their conjugates in DMSO.

Afiliacje autorów:
Shereen A. M. - inna afiliacja
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
Saad M. - inna afiliacja
3.  Nnaemeka N., Nwaji N., Gertrude F., John M., Tebello N., Inhibition of Aluminium Corrosion Using Benzothiazole and Its Phthalocyanine Derivative, Electrocatlysis, ISSN: 1868-5994, DOI: 10.1007/s12678-019-00538-1, Vol.10, pp.445-458, 2019

Streszczenie:
Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol-
2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride
(ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration
range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range
from 28.2 to 76.1%for BTand from 71.5 to 82.7%for ClGaBTPc. The latter was a better inhibitor. Scanning electronmicroscopy
and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding
it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results

Afiliacje autorów:
Nnaemeka N. - inna afiliacja
Nwaji N. - IPPT PAN
Gertrude F. - inna afiliacja
John M. - inna afiliacja
Tebello N. - inna afiliacja
4.  Nnaemeka N., Nwaji N., John M., Tebello N., Corrosion Resistance of Aluminum against Acid Activation: Impact of Benzothiazole-Substituted Gallium Phthalocyanine, Molecules, ISSN: 1420-3049, DOI: 10.3390/molecules24010207, Vol.24, pp.4-22, 2019

Streszczenie:
This study describes the adsorption behavior of organic inhibitors at the aluminum-HCl
solution interface and their corrosion inhibition performance. The organic inhibitors employed are:
4-(benzo [d]thiazol-2ylthio)phthalonitrile (BTThio) and tetrakis[(benzo[d]thiazol-2-yl-thio)phthalocyaninato]
gallium(III) chloride (ClGaBTThioPc). The corrosion behavior of these inhibitors is
investigated using electrochemical and computational techniques. Open circuit potential results
reveal predominant cathodic character for the mechanism of aluminum corrosion inhibition by the
inhibitors. Inhibition efficiency values from potentiodynamic polarization measurements increase
from 46.9 to 70.8% for BTThio and 59.7 to 81.0% for ClGaBTThioPc within the concentration range of
2 to 10 M. Scanning electron microscopy (SEM) measurements reveal protection of the metal surface
from acid attack, in the presence of the inhibitors and energy dispersive X-ray (EDX) measurements
show that the most probable way by which the inhibitors protect the metal surface would be
by shielding it from the corrosion attacks of Cl

Afiliacje autorów:
Nnaemeka N. - inna afiliacja
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
5.  Bokolombe P. N., Zweli H., Nwaji N., Gertrude F., John M., Tebello N., Photophysical and optical limiting properties at 532 nm of BODIPY dyes with p-benzyloxystyryl groups at the 3,5-positions, Journal of Porphyrins and Phthalocyanines, ISSN: 1088-4246, DOI: 10.1142/S1088424617500857, Vol.22, pp.413-422, 2018

Streszczenie:
The synthesis and characterization of a series of 3,5-di-p
-benzyloxystyrylBODIPY dyes with different substituents at the meso-aryl position is reported. The photophysical and nonlinear optical properties are described. BODIPYs of this type are found to be suitable for optical limiting at 532 nm on the nanosecond timescale. An enhancement of the population of the T1
state through the incorporation of bromine atoms at the 2,6-positions does not result in an enhancement of the optical limiting properties on a nanosecond timescale. This suggests that, in contrast with phthalocyanines, access to excited state absorption (ESA) from the T1
state through the introduction of a heavy atom effect does not provide a significantly improved reverse saturable absorbance response compared to ESA from the S1
state.

Afiliacje autorów:
Bokolombe P. N. - inna afiliacja
Zweli H. - inna afiliacja
Nwaji N. - inna afiliacja
Gertrude F. - inna afiliacja
John M. - inna afiliacja
Tebello N. - inna afiliacja
6.  Edith D., Nwaji N., John M., Tebello N., the photophysicochemical behavior of symmetric and asymmetric zinc phthalocyanine surface assembled onto gold nanotriangles, New Journal of chemistry, ISSN: 1144-0546, DOI: 10.1039/C8NJ02746C, Vol.42, pp.14290-14299, 2018

Streszczenie:
The synthesis of a novel asymmetric phthalocyanine, (4-(4-(benzo[d]thiazol-2-yl)phenoxy)-2,10,17-tris(4-(2-carboxyethyl)phenoxy)phthalocyaninatol)zinc(II), complex 3, is reported. Complex 3 together with the previously reported complexes tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (4) and 3-(4-((3,17,23-tris(4-(benzo[d]thiazol-2-yl)phenoxy)phthalocyaninatol)oxy)phenyl)propanoic acid zinc(II) (5), were linked to gold nanotriangles (AuNTs) through S–Au/Au–N self-assembly to afford the conjugates (3-AuNTs, 4-AuNTs and 5-AuNTs). The photophysicochemical behaviour of the complexes and their conjugates were studied. The asymmetric complexes 3 and 5, displayed improved triplet and singlet oxygen quantum yields compared to the symmetric complex 4, while all conjugates displayed improved triplet and singlet oxygen quantum yields compared to their respective complexes alone. The complexes and their conjugates could serve as good candidates for photodynamic therapy.

Afiliacje autorów:
Edith D. - inna afiliacja
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
7.  Nwaji N., John M., Tebello N., Photophysical and strong optical limiting properties of ball-type phthalocyanines dimers and their monomeric analogues, Journal of Photochemistry and Photobiology A, ISSN: 1010-6030, DOI: 10.1016/j.jphotochem.2017.10.045, Vol.352, pp.73-85, 2018

Streszczenie:
The nonlinear optical behaviors of ball-type phthalocyanine complexes: 10,11,’150,250-tetrakis-[4,40-((4-
formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 10,11,’150,250-tetrakis-[4,40-((4-formyl-1,2-
bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 10, 11,’150,250-tetrakis-4,40-((4-formyl-
1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric
derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at
532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in
solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting
properties compared to the monomeric derivatives. The beff values for the dimeric complexes 5–7 were
found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding
monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes
were formulated in thin
films. The second order hyperpolarizability values were in order of 1028–
1026 esu in solution and 1027–1026 in
films.

Afiliacje autorów:
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
8.  Nwaji N., Somila D., John M., Tebello N., Phototophysical and enhanced nonlinear optical response in asymetric benzothiazole substituted phthalocyanine covalently linked to semiconductor quantum dots, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, ISSN: 1386-1425, DOI: 10.1016/j.saa.2018.06.098, Vol.204, pp.629-639, 2018

Streszczenie:
The synthesis of asymmetric benzothiazole substituted phthalocyanines (complexes 3 to 5) and their covalent
attachment to glutathione (GSH) functionalized quantum dots (QDs) are reported in this work. Additionally,
their photophysical and nonlinear optical properties were investigated. A decrease in the fluorescence quantum
yield with corresponding increase in the triplet quantum yield was observed when the complexes were covalently
linked to glutathione (GSH) functionalized cadmiumtelluride (CdTe) quantumdots. Reverse saturable absorptionwas
found to be predominantly dominated by excited state absorption. The observed limiting threshold
values range from 0.29–0.75 J/cm2.

Afiliacje autorów:
Nwaji N. - IPPT PAN
Somila D. - inna afiliacja
John M. - inna afiliacja
Tebello N. - inna afiliacja
9.  Nwaji N., John M., Tebello N., An optical limiting study in aminophenoxy substituted phthalocyanine in the presence of semiconductor quantum dots, Journal of Luminescence, ISSN: 0022-2313, Vol.203, pp.247-256, 2018

Streszczenie:
The synthesis of 4-bis(4-aminophenoxy)phenoxy derivatized phthalocyanine containing In (complex 2), and Ga
(complex 3), and the previously reported complex 4 (containing Zn) and their covalent attachment to glutathione
(GSH) functionalized cadmium telluride quantum dots (CdTe QDs) are reported in this work.
Additionally, their photophysical, energy transfer and nonlinear optical properties were investigated. The
covalently linked derivatives showed lower fluorescence quantum yields with corresponding higher triplet
quantum yields. Quenching of the photoluminescence intensity of the CdTe QDs was observed to be due to
energy transfer from the QDs to phthalocyanine (Pcs) molecules. The reverse saturable absorption nonlinear
optical response was found to be predominantly dependent on the excited state absorption. The observed limiting
threshold ranges from 0.04 to 0.62 J/cm−2.

Afiliacje autorów:
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
10.  Edith D., Nwaji N., David O. O., John M., Tebello N., Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles, Journal of Photochemistry and Photobiology A, ISSN: 1010-6030, DOI: 10.1016/j.jphotochem.2017.09.020, Vol.349, pp.148-161, 2017

Streszczenie:
The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.

Afiliacje autorów:
Edith D. - inna afiliacja
Nwaji N. - IPPT PAN
David O. O. - inna afiliacja
John M. - inna afiliacja
Tebello N. - inna afiliacja
11.  Nwaji N., John M., Tebello N., 4-Bis (4-aminophenoxy)phenoxy derivitized phthalocyanine conjugated to metallic nanoparticles: searching for enhanced optical limiting materials, New Journal of chemistry, ISSN: 1144-0546, DOI: 10.1039/C7NJ02718D, Vol.41, pp.1-15, 2017

Streszczenie:
n this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of 4-(2,4-bis(4-aminophenoxy)phenoxy) phthalocyinato zinc(II) phthalocyanine (6) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques using 532 nm nanosecond pulses. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibit higher excited state absorption cross-section compared to ground state absorption. Enhanced optical limiting performance was observed when complex 6 was conjugated to nanoparticles with 6CB-AuNPs (CB = covalent bond) showing the highest optical limiting threshold of 0.36 J cm−2.

Afiliacje autorów:
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Tebello N. - inna afiliacja
12.  Nwaji N., Benjamin J., John M., David O. O., Tebello N., Nonlinear optical dynamics of benzothiazole derivatized phthalocyanines in solution, thin films and when conjugated to nanoparticles, Journal of Photochemistry and Photobiology A, ISSN: 1010-6030, DOI: 10.1016/j.jphotochem.2017.05.042, Vol.346, pp.73-85, 2017

Streszczenie:
Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.

Afiliacje autorów:
Nwaji N. - IPPT PAN
Benjamin J. - inna afiliacja
John M. - inna afiliacja
David O. O. - inna afiliacja
Tebello N. - inna afiliacja
13.  Nwaji N., John M., Jonathan B., Tebello N., Synthesis, photophysical and nonlinear optical properties of a series of ball-type phthalocyanines in solution and thin films, New Journal of chemistry, ISSN: 1144-0546, DOI: 10.1039/C6NJ03662G, Vol.41, pp.1-15, 2017

Streszczenie:
In this study, we report on the enhanced nonlinear optical properties of novel tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato zinc(II)) (4), tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium chloride) (5) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato indium chloride) (6) both in solution and when embedded in polymer thin films. Complexes 5 and 6 bearing heavy atoms showed enhanced triplet quantum yield and nonlinear optical response. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. Time dependent density functional theory (TD-DFT) calculations were performed in order to explain the origin of the observed UV-vis and magnetic circular dichroism (MCD) spectra of the complexes.

Afiliacje autorów:
Nwaji N. - IPPT PAN
John M. - inna afiliacja
Jonathan B. - inna afiliacja
Tebello N. - inna afiliacja
14.  Nwaji N., David O. O., John M., Marcel L., Samson K., Jonathan B., Tebello N., Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles, Dyes and Pigments, ISSN: 1873-3743, DOI: 10.1016/j.dyepig.2017.01.066, Vol.140, pp.417-430, 2017

Streszczenie:
The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.

Afiliacje autorów:
Nwaji N. - IPPT PAN
David O. O. - inna afiliacja
John M. - inna afiliacja
Marcel L. - inna afiliacja
Samson K. - inna afiliacja
Jonathan B. - inna afiliacja
Tebello N. - inna afiliacja

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