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RSC Advances
Three tridentate Schiff base ligands were synthesized from the reactions between 2-picolylamine a... more Three tridentate Schiff base ligands were synthesized from the reactions between 2-picolylamine and salicylaldehyde derivatives (3-ethoxy (OEt), 4-diethylamino (NEt2) and 4-hydroxy (OH)).
Journal of Molecular Graphics and Modelling
Molecules
This study describes the synthesis, theoretical investigations, and photocatalytic degradational ... more This study describes the synthesis, theoretical investigations, and photocatalytic degradational properties of a new (pyrazine)(meso-tetrakis(4-tert-methoxyphenyl)-porphyrinato)-cadmium (II) ([Cd(TMPP)-Pyz] complex (1). The new penta-coordinated CdII porphyrin complex (1) was characterized by various spectroscopic techniques, including FT-IR, NMR, UV-visible absorption, fluorescence emission, and singlet oxygen, while its molecular structure was studied using single crystal X-ray diffraction. The UV–Vis spectroscopic study highlighted the redshift of the absorption bands after the insertion of the Cd(II) metal ion into the TMPP ring. The co-coordination of the pyrazine axial ligand enhanced this effect. A fluorescence emission spectroscopic study showed a significant blueshift in the Q bands, accompanied by a decrease in the fluorescence emission intensity and quantum yields of Φf = 0.084, Φf = 0.06 and Φf = 0.03 for H2-TMPP free-base porphyrin, [Cd(TMPP)] and [Cd(TMPP)(Pyz)] (1) re...
Polyhedron
Four complexes were synthesized and characterized with the formula [Cu(N^N)(PMePh2)2]ClO4 (4 and ... more Four complexes were synthesized and characterized with the formula [Cu(N^N)(PMePh2)2]ClO4 (4 and 6) or [Cu(N^N)(dppe)]ClO4 (5) and 7){N^N = 2,2′-biquinoline, neocuproine}. Crystal structures of the neocuproine-containing complexes (5 and 7) were obtained and described. The methyldiphenylphosphine-containing complexes are stable in solutions (compared to PPh3) due to: (1) slightly better σ-donation compared to PPh3 and (2) smaller Tolman cone angle of ∼136° (compared to ∼145° in PPh3). In the other hand, [Cu(N^N)(dppe)]ClO4 complexes were demonstrating evidence of forming [Cu(N^N)2]+ in solutions, highlighting the importance of the P-Cu-P angle. The angle P-Cu-P is around 123° in stable complex 5 compared to ∼92° in 7. Absorption spectra of 4 and 5 exhibit low intensity broad shoulder in the visible light domain assigned as MLLCT by computational studies. While [Cu(2,2′-biquinoline)(PPh3)2]+ cation was losing catalytic activity in Castero-Stephens cross-coupling over time as indicated by the low conversion rate, complexes 4 and 5 found to be active and achieved complete conversion of the starting materials.
Discover Chemical Engineering, 2022
The electrochemical reduction of carbon dioxide is a promising method for both recycling of atmos... more The electrochemical reduction of carbon dioxide is a promising method for both recycling of atmospheric CO2 and storing renewably produced electrical energy in stable chemical bonds. In this paper, we review the current challenges within this promising area of research. Here we provide an overview of key findings from the perspective of improving the selectivity of reduction products, to serve as a contextual foundation from which a firmer understanding of the field can be built. Additionally, we discuss recent innovations in the development of catalytic materials selective toward C3 and liquid products. Through this, we form a basis from which key mechanisms into C3 products may be further examined. Carbon–carbon (C–C) bond formation provides a key step in the reduction of CO2 to energy dense and high value fuels. Here we demonstrate how variations in catalytic surface morphology and reaction kinetics influence the formation of multi-carbon products through their impact on the form...
Molecules, 2020
Ruthenium(II) arene complexes of the general formula [RuCl(η6-p-cymene)(diamine)]PF6 (diamine = 1... more Ruthenium(II) arene complexes of the general formula [RuCl(η6-p-cymene)(diamine)]PF6 (diamine = 1,2-diaminobenzene (1), 2,3-diaminonaphthalene (2), 9,10-diaminophenanthrene (3), 2,3-diaminophenazine (4), and 1,2-diaminoanthraquinone (5) were synthesized. Chloro/aqua exchange was evaluated experimentally for complexes 1 and 2. The exchange process was investigated theoretically for all complexes, revealing relatively fast exchange with no significant influence from the polycyclic aromatic diamines. The calf thymus DNA (CT-DNA) binding of the complexes increased dramatically upon extending the aromatic component of the diamines, as evaluated by changes in absorption spectra upon titration with different concentrations of CT-DNA. An intercalation binding mode was established for the complexes using the increase in the relative viscosity of the CT-DNA following addition of complexes 1 and 2. Theoretical studies showed strong preference for replacement of water by guanine for all the com...
Inorganica Chimica Acta, 2021
In this work, a new cadmium(II) complex namely the (1,4-diazabicyclo[2.2.2]octane)(mesotetrakis(4... more In this work, a new cadmium(II) complex namely the (1,4-diazabicyclo[2.2.2]octane)(mesotetrakis(4-tert-methoxyphenyl)porphyrinato)cadmium(II) with the formula [Cd(TMPP)(DABCO)] (I) (DABCO = 1,4-diazabicyclo[2.2.2]octane) was successfully synthetized. The structure of (I) have been characterized by FT-IR, 1 HNMR, UV-visible, fluorescence spectroscopies and single crystal Xray diffraction technique. DFT calculations has been made for the structural, 1 H NMR spectroscopy and IR spectra analysis. The adsorption of methylene blue (MB) dye was studied to examine the efficiently of the [Cd(TMPP)(DABCO)] for removing the cationic dyes from aqueous solution. The Langmuir adsorption capacity (Q 0 max) at 290 K and pH 7.0 was found to be 69.24 mg.g-1. The adsorption mechanism which involved π-π interaction between the MB dye molecule and the porphyrin ring of (I) is well described by the pseudo second-order and Elovich models.
Theoretical Chemistry Accounts, 2017
ACS Catalysis, 2016
We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and ... more We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO 2 to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of −1.0 mA cm −2 at −0.6 V vs. RHE, compared to the CO FE of 63% and −2.1 mA cm −2 for OD-Cu. Excess Sn on the surface caused H 2 evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu-Sn alloy. Auger electron spectroscopy of the sample surface exhibits zero-valent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multi-fold sites on pure Cu,
The (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase or IspH is an enzyme, containing an ir... more The (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase or IspH is an enzyme, containing an iron-sulfur cluster, important for the life cycle of many pathogenic bacteria. It catalyzes the conversion of (E)-4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) into the isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). IPP and DMAPP are the building blocks of isoprenoids or terpenes such as vitamins, steroid hormones and carotenoids. Here we used state-of-the-art DFT within a broken symmetry approach, coupled with ONIOM techniques, to investigate the reaction mechanism promoted by IspH. Several mechanistic insights are gained from our study. The first step involves the rotation of the hydroxyl group of the substrate from the Fe-bound state into a state presenting a H-bond with E126. Elimination of the hydroxyl group is initiated by a proton transfer form E126 to the substrate. This step does not involve an electron transfer or very limited from the iron-sulfur cluster...
Chemical Science, 2015
We report an integrated QM/MM study of the bio-organometallic reaction pathway of the reductive d... more We report an integrated QM/MM study of the bio-organometallic reaction pathway of the reductive dehydroxylation of (E)-4-hydroxy-3-methylbut-2-enyl pyrophosphate (HMBPP).
Angewandte Chemie, 2014
The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly... more The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO 2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO 2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO 2 provides guidelines for further improving electrocatalysis.
RSC Advances
Three tridentate Schiff base ligands were synthesized from the reactions between 2-picolylamine a... more Three tridentate Schiff base ligands were synthesized from the reactions between 2-picolylamine and salicylaldehyde derivatives (3-ethoxy (OEt), 4-diethylamino (NEt2) and 4-hydroxy (OH)).
Journal of Molecular Graphics and Modelling
Molecules
This study describes the synthesis, theoretical investigations, and photocatalytic degradational ... more This study describes the synthesis, theoretical investigations, and photocatalytic degradational properties of a new (pyrazine)(meso-tetrakis(4-tert-methoxyphenyl)-porphyrinato)-cadmium (II) ([Cd(TMPP)-Pyz] complex (1). The new penta-coordinated CdII porphyrin complex (1) was characterized by various spectroscopic techniques, including FT-IR, NMR, UV-visible absorption, fluorescence emission, and singlet oxygen, while its molecular structure was studied using single crystal X-ray diffraction. The UV–Vis spectroscopic study highlighted the redshift of the absorption bands after the insertion of the Cd(II) metal ion into the TMPP ring. The co-coordination of the pyrazine axial ligand enhanced this effect. A fluorescence emission spectroscopic study showed a significant blueshift in the Q bands, accompanied by a decrease in the fluorescence emission intensity and quantum yields of Φf = 0.084, Φf = 0.06 and Φf = 0.03 for H2-TMPP free-base porphyrin, [Cd(TMPP)] and [Cd(TMPP)(Pyz)] (1) re...
Polyhedron
Four complexes were synthesized and characterized with the formula [Cu(N^N)(PMePh2)2]ClO4 (4 and ... more Four complexes were synthesized and characterized with the formula [Cu(N^N)(PMePh2)2]ClO4 (4 and 6) or [Cu(N^N)(dppe)]ClO4 (5) and 7){N^N = 2,2′-biquinoline, neocuproine}. Crystal structures of the neocuproine-containing complexes (5 and 7) were obtained and described. The methyldiphenylphosphine-containing complexes are stable in solutions (compared to PPh3) due to: (1) slightly better σ-donation compared to PPh3 and (2) smaller Tolman cone angle of ∼136° (compared to ∼145° in PPh3). In the other hand, [Cu(N^N)(dppe)]ClO4 complexes were demonstrating evidence of forming [Cu(N^N)2]+ in solutions, highlighting the importance of the P-Cu-P angle. The angle P-Cu-P is around 123° in stable complex 5 compared to ∼92° in 7. Absorption spectra of 4 and 5 exhibit low intensity broad shoulder in the visible light domain assigned as MLLCT by computational studies. While [Cu(2,2′-biquinoline)(PPh3)2]+ cation was losing catalytic activity in Castero-Stephens cross-coupling over time as indicated by the low conversion rate, complexes 4 and 5 found to be active and achieved complete conversion of the starting materials.
Discover Chemical Engineering, 2022
The electrochemical reduction of carbon dioxide is a promising method for both recycling of atmos... more The electrochemical reduction of carbon dioxide is a promising method for both recycling of atmospheric CO2 and storing renewably produced electrical energy in stable chemical bonds. In this paper, we review the current challenges within this promising area of research. Here we provide an overview of key findings from the perspective of improving the selectivity of reduction products, to serve as a contextual foundation from which a firmer understanding of the field can be built. Additionally, we discuss recent innovations in the development of catalytic materials selective toward C3 and liquid products. Through this, we form a basis from which key mechanisms into C3 products may be further examined. Carbon–carbon (C–C) bond formation provides a key step in the reduction of CO2 to energy dense and high value fuels. Here we demonstrate how variations in catalytic surface morphology and reaction kinetics influence the formation of multi-carbon products through their impact on the form...
Molecules, 2020
Ruthenium(II) arene complexes of the general formula [RuCl(η6-p-cymene)(diamine)]PF6 (diamine = 1... more Ruthenium(II) arene complexes of the general formula [RuCl(η6-p-cymene)(diamine)]PF6 (diamine = 1,2-diaminobenzene (1), 2,3-diaminonaphthalene (2), 9,10-diaminophenanthrene (3), 2,3-diaminophenazine (4), and 1,2-diaminoanthraquinone (5) were synthesized. Chloro/aqua exchange was evaluated experimentally for complexes 1 and 2. The exchange process was investigated theoretically for all complexes, revealing relatively fast exchange with no significant influence from the polycyclic aromatic diamines. The calf thymus DNA (CT-DNA) binding of the complexes increased dramatically upon extending the aromatic component of the diamines, as evaluated by changes in absorption spectra upon titration with different concentrations of CT-DNA. An intercalation binding mode was established for the complexes using the increase in the relative viscosity of the CT-DNA following addition of complexes 1 and 2. Theoretical studies showed strong preference for replacement of water by guanine for all the com...
Inorganica Chimica Acta, 2021
In this work, a new cadmium(II) complex namely the (1,4-diazabicyclo[2.2.2]octane)(mesotetrakis(4... more In this work, a new cadmium(II) complex namely the (1,4-diazabicyclo[2.2.2]octane)(mesotetrakis(4-tert-methoxyphenyl)porphyrinato)cadmium(II) with the formula [Cd(TMPP)(DABCO)] (I) (DABCO = 1,4-diazabicyclo[2.2.2]octane) was successfully synthetized. The structure of (I) have been characterized by FT-IR, 1 HNMR, UV-visible, fluorescence spectroscopies and single crystal Xray diffraction technique. DFT calculations has been made for the structural, 1 H NMR spectroscopy and IR spectra analysis. The adsorption of methylene blue (MB) dye was studied to examine the efficiently of the [Cd(TMPP)(DABCO)] for removing the cationic dyes from aqueous solution. The Langmuir adsorption capacity (Q 0 max) at 290 K and pH 7.0 was found to be 69.24 mg.g-1. The adsorption mechanism which involved π-π interaction between the MB dye molecule and the porphyrin ring of (I) is well described by the pseudo second-order and Elovich models.
Theoretical Chemistry Accounts, 2017
ACS Catalysis, 2016
We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and ... more We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO 2 to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of −1.0 mA cm −2 at −0.6 V vs. RHE, compared to the CO FE of 63% and −2.1 mA cm −2 for OD-Cu. Excess Sn on the surface caused H 2 evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu-Sn alloy. Auger electron spectroscopy of the sample surface exhibits zero-valent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multi-fold sites on pure Cu,
The (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase or IspH is an enzyme, containing an ir... more The (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase or IspH is an enzyme, containing an iron-sulfur cluster, important for the life cycle of many pathogenic bacteria. It catalyzes the conversion of (E)-4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) into the isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). IPP and DMAPP are the building blocks of isoprenoids or terpenes such as vitamins, steroid hormones and carotenoids. Here we used state-of-the-art DFT within a broken symmetry approach, coupled with ONIOM techniques, to investigate the reaction mechanism promoted by IspH. Several mechanistic insights are gained from our study. The first step involves the rotation of the hydroxyl group of the substrate from the Fe-bound state into a state presenting a H-bond with E126. Elimination of the hydroxyl group is initiated by a proton transfer form E126 to the substrate. This step does not involve an electron transfer or very limited from the iron-sulfur cluster...
Chemical Science, 2015
We report an integrated QM/MM study of the bio-organometallic reaction pathway of the reductive d... more We report an integrated QM/MM study of the bio-organometallic reaction pathway of the reductive dehydroxylation of (E)-4-hydroxy-3-methylbut-2-enyl pyrophosphate (HMBPP).
Angewandte Chemie, 2014
The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly... more The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO 2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO 2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO 2 provides guidelines for further improving electrocatalysis.