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Kottaichamy AR, Nazrulla MA, Parmar M, Thimmappa R, Devendrachari MC, Vinod CP, Volokh M, Kotresh HMN, Shalom M, Thotiyl MO. Ligand Isomerization Driven Electrocatalytic Switching. Angew Chem Int Ed Engl 2024; 63:e202405664. [PMID: 38695160 DOI: 10.1002/anie.202405664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Indexed: 06/21/2024]
Abstract
The prevailing view about molecular catalysts is that the central metal ion is responsible for the reaction mechanism and selectivity, whereas the ligands mainly affect the reaction kinetics. Here, we question this paradigm and show that ligands have a dramatic influence on the selectivity of the product. We show how even a seemingly small change in ligand isomerization sharply alters the selectivity of the well-researched oxygen reduction reaction (ORR) Co phthalocyanine catalyst from an indirect 2e- to a direct 4e- pathway. Detailed analysis reveals that intramolecular hydrogen-bond interactions in the ligand activate the catalytic Co, directing the oxygen binding and thus deciding the final product. The resulting catalyst is the first example of a Co-based molecular catalyst catalyzing a direct 4e- ORR via ligand isomerization, for which it shows an activity close to the benchmark Pt in an actual H2-O2 fuel cell. The effect of the ligand isomerism is demonstrated with different central metal ions, thus highlighting the generalizability of the findings and their potential to open new possibilities in the design of molecular catalysts.
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Affiliation(s)
- Alagar Raja Kottaichamy
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
| | | | - Muskan Parmar
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Ravikumar Thimmappa
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | | | | | - Michael Volokh
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
| | | | - Menny Shalom
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
| | - Musthafa Ottakam Thotiyl
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
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Odintsova EG, Petrenko VE, Kolker AM, Borovkov NY. Molecular origin of structural defects in the zinc phthalocyanine film. Phys Chem Chem Phys 2022; 24:19956-19964. [PMID: 35971772 DOI: 10.1039/d2cp01221a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Controlling the growth of thin phthalocyanine films is a long-term challenge for the science of applied nanomaterials. So, this contribution deals with films of unsubstituted zinc phthalocyanine (ZnPc) and seeks to acquire structural information that is unavailable via physical experiments, thus, finding out how the film morphology can be seriously improved. A model of the vapor-deposited film has been created using the molecular dynamics method. Specifically, the ZnPc molecules are dosed into the simulation box under normal conditions, reproducing key features of the real film, such as the trimolecular wetting layer and the island-like three-dimensional (3D) phase that is structured like the α-polymorph; then all film fragments are characterized via their radial distribution functions and mean-squared displacements. The simulation model indicates that the 3D phase starts to develop smoothly through multimolecular cofacial stacking but finally becomes fragmental because the wetting layer is too meager to be a good platform for regular film growth. Accordingly, the film morphology may be improved if the wetting layer is thickened via restraining the vertical development of the 3D phase. Following this idea, uniform ZnPc films impaired by neither grain boundaries nor coarser defects were deposited from solutions and visualized at the nanometer scale.
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Affiliation(s)
- E G Odintsova
- G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045, Russian Federation.
| | - V E Petrenko
- G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045, Russian Federation.
| | - A M Kolker
- G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045, Russian Federation.
| | - N Y Borovkov
- G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045, Russian Federation.
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3
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Mukhopadhyay S, Kottaichamy AR, Bhat ZM, Dargily NC, Thotiyl MO. Isomerism‐Activity Relation in Molecular Electrocatalysis: A Perspective. ELECTROANAL 2020. [DOI: 10.1002/elan.202060244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sanchayita Mukhopadhyay
- Indian Institute of Science Education and Research (IISER) Pune Dr. Homi Bhabha Road, Pashan Pune 411008 India
| | - Alagar Raja Kottaichamy
- Indian Institute of Science Education and Research (IISER) Pune Dr. Homi Bhabha Road, Pashan Pune 411008 India
| | - Zahid Manzoor Bhat
- Indian Institute of Science Education and Research (IISER) Pune Dr. Homi Bhabha Road, Pashan Pune 411008 India
| | - Neethu Christudas Dargily
- Indian Institute of Science Education and Research (IISER) Pune Dr. Homi Bhabha Road, Pashan Pune 411008 India
| | - Musthafa Ottakam Thotiyl
- Indian Institute of Science Education and Research (IISER) Pune Dr. Homi Bhabha Road, Pashan Pune 411008 India
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4
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Märker B, Hiller J, Wackenhut F, Braun K, Meixner A, Scheele M. Simultaneous positive and negative optical patterning with dye-sensitized CdSe quantum dots. J Chem Phys 2019; 151:141102. [DOI: 10.1063/1.5124232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Björn Märker
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Jonas Hiller
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Frank Wackenhut
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Kai Braun
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Alfred Meixner
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors and Analytics LISA+, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Marcus Scheele
- Institute for Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors and Analytics LISA+, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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5
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Sarfo DK, Sivanesan A, Izake E, Ayoko GA. Rapid detection of mercury contamination in water by surface enhanced Raman spectroscopy. RSC Adv 2017. [DOI: 10.1039/c7ra02209c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mercury (Hg) is a potent neurotoxin in fish, wildlife, and humans.
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Affiliation(s)
- Daniel K. Sarfo
- Queensland University of Technology (QUT)
- School of Chemistry
- Physics and Mechanical Engineering
- Nanotechnology and Molecular Science
- Australia
| | - Arumugam Sivanesan
- Queensland University of Technology (QUT)
- School of Chemistry
- Physics and Mechanical Engineering
- Nanotechnology and Molecular Science
- Australia
| | - Emad L. Izake
- Queensland University of Technology (QUT)
- School of Chemistry
- Physics and Mechanical Engineering
- Nanotechnology and Molecular Science
- Australia
| | - Godwin A. Ayoko
- Queensland University of Technology (QUT)
- School of Chemistry
- Physics and Mechanical Engineering
- Nanotechnology and Molecular Science
- Australia
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6
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Nyoni S, Mashazi P, Nyokong T. Electrode modification using nanocomposites of electropolymerised cobalt phthalocyanines supported on multiwalled carbon nanotubes. J Solid State Electrochem 2015. [DOI: 10.1007/s10008-015-2985-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Sivanesan A, Adamkiewicz W, Kalaivani G, Kamińska A, Waluk J, Hołyst R, Izake EL. Towards improved precision in the quantification of surface-enhanced Raman scattering (SERS) enhancement factors: a renewed approach. Analyst 2015; 140:489-96. [PMID: 25374971 DOI: 10.1039/c4an01778a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
This paper demonstrates a renewed procedure for the quantification of surface-enhanced Raman scattering (SERS) enhancement factors with improved precision. The principle of this method relies on deducting the resonance Raman scattering (RRS) contribution from surface-enhanced resonance Raman scattering (SERRS) to end up with the surface enhancement (SERS) effect alone. We employed 1,8,15,22-tetraaminophthalocyanato-cobalt(II) (4α-Co(II)TAPc), a resonance Raman- and electrochemically redox-active chromophore, as a probe molecule for RRS and SERRS experiments. The number of 4α-Co(II)TAPc molecules contributing to RRS and SERRS phenomena on plasmon inactive glassy carbon (GC) and plasmon active GC/Au surfaces, respectively, has been precisely estimated by cyclic voltammetry experiments. Furthermore, the SERS substrate enhancement factor (SSEF) quantified by our approach is compared with the traditionally employed methods. We also demonstrate that the present approach of SSEF quantification can be applied for any kind of different SERS substrates by choosing an appropriate laser line and probe molecule.
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Affiliation(s)
- Arumugam Sivanesan
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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9
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Maringa A, Nyokong T. Behavior of Palladium Nanoparticles in the Absence or Presence of Cobalt Tetraaminophthalocyanine for the Electrooxidation of Hydrazine. ELECTROANAL 2014. [DOI: 10.1002/elan.201400028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Self-assembled monolayer of 2,9,16,23-tetrahydroxythiophenylphthalocyanatocobalt(II) on gold electrode and its electrocatalytic activity towards dioxygen reduction. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2013.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Layer-by-layer self assembly of a water-soluble phthalocyanine on gold. Application to the electrochemical determination of hydrogen peroxide. Bioelectrochemistry 2013; 91:21-7. [DOI: 10.1016/j.bioelechem.2012.12.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 11/25/2012] [Accepted: 12/03/2012] [Indexed: 11/20/2022]
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12
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Fabrication of optochemical and electrochemical sensors using thin films of porphyrin and phthalocyanine derivatives. J CHEM SCI 2013. [DOI: 10.1007/s12039-012-0330-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Self assembled films of porphyrins with amine groups at different positions: influence of their orientation on the corrosion inhibition and the electrocatalytic activity. Molecules 2012; 17:7824-42. [PMID: 22735784 PMCID: PMC6268965 DOI: 10.3390/molecules17077824] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 06/08/2012] [Accepted: 06/12/2012] [Indexed: 11/17/2022] Open
Abstract
Self-assembled molecular films of two cobalt porphyrins with amine groups at different positions—(5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II), [Co(II) (T(o-NH2)PP)] and (5,10,15,20-tetrakis-(4-aminophenyl) porphyrin-cobalt(II), [Co(II)(T(p-NH2)PP)]—were formed on a gold substrate. The functionalized surfaces were characterized using Raman spectroscopy, atomic force microscopy and electrochemical methods. Both modified gold surfaces completely mask the charge transfer of a [Fe(CN)6]3−/4− redox couple in solution, indicating the layer is highly resistive in behavior. Electrochemical impedance spectroscopy analyses revealed that the porphyrin film with amine groups at ortho positions shows a higher charge-transfer resistance with a better protective behavior compared to the para position modified surface. Raman, AFM and EIS data suggests that an ortho amine positioned molecule forms a more compact layer compared to the para-positioned molecule. This can be explained in terms of their orientation on the gold surface. [Co(II)(T(o-NH2)PP)] adopted a saddle shape orientation whereas [Co(II)(T(p-NH2)PP)] adopted a flat orientation on the gold surface. The porphyrin modified gold electrode catalyzes the oxygen reduction at lower potentials compared to the bare gold electrode. The shift in the overvoltage was higher in case of molecules with flat orientation compared to the saddle shaped oriented porphyrin molecules on the surface.
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Routaboul L, Braunstein P, Xiao J, Zhang Z, Dowben PA, Dalmas G, Da Costa V, Félix O, Decher G, Rosa LG, Doudin B. Altering the static dipole on surfaces through chemistry: molecular films of zwitterionic quinonoids. J Am Chem Soc 2012; 134:8494-506. [PMID: 22509815 DOI: 10.1021/ja212104b] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The adsorption of molecular films made of small molecules with a large intrinsic electrical dipole has been explored. The data indicate that such dipolar molecules may be used for altering the interface dipole screening at the metal electrode interface in organic electronics. More specifically, we have investigated the surface electronic spectroscopic properties of zwitterionic molecules containing 12π electrons of the p-benzoquinonemonoimine type, C(6)H(2)(···NHR)(2)(···O)(2)(R = H (1), n-C(4)H(9) (2), C(3)H(6)-S-CH(3) (3), C(3)H(6)-O-CH(3) (4), CH(2)-C(6)H(5) (5)), adsorbed on Au. These molecules are stable zwitterions by virtue of the meta positions occupied by the nitrogen and oxygen substituents on the central ring, respectively. The structures of 2-4 have been determined by single crystal X-ray diffraction and indicate that in these molecules, two chemically connected but electronically not conjugated 6π electron subunits are present, which explains their strong dipolar character. We systematically observed that homogeneous molecular films with thickness as small as 1 nm were formed on Au, which fully cover the surface, even for a variety of R substituents. Preferential adsorption toward the patterned gold areas on SiO(2) substrates was found with 4. Optimum self-assembling of 2 and 5 results in ordered close packed films, which exhibit n-type character, based on the position of the Fermi level close to the conduction band minimum, suggesting high conductivity properties. This new type of self-assembled molecular films offers interesting possibilities for engineering metal-organic interfaces, of critical importance for organic electronics.
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Affiliation(s)
- Lucie Routaboul
- Laboratoire de Chimie de Coordination, Institut de Chimie, Université de Strasbourg, France
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Jeevagan AJ, John SA. Electrochemical sensor for guanine using a self-assembled monolayer of 1,8,15,22-tetraaminophthalocyanatonickel(II) on glassy carbon electrode. Anal Biochem 2012; 424:21-6. [PMID: 22330605 DOI: 10.1016/j.ab.2012.02.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 02/01/2012] [Accepted: 02/02/2012] [Indexed: 10/14/2022]
Abstract
This article describes the selective determination of guanine (G) using the self-assembled monolayer (SAM) of 1,8,15,22-tetraaminophthalocyanatonickel(II) (4α-Ni(II)TAPc) modified glassy carbon electrode (GCE) in 0.2 M acetate buffer solution (pH 4.0). The SAM of 4α-Ni(II)TAPc was formed on GCE by spontaneous adsorption of 1 mM 4α-Ni(II)TAPc in dimethylformamide (DMF). It shows two pairs of redox waves corresponding to Ni(III)/Ni(II) and Ni(III)Pc(-1)/Ni(III)Pc(-2) in 0.2 M acetate buffer solution. The SAM modified electrode exhibits excellent electrocatalytic activity toward the oxidation of G by enhancing its oxidation current with 150 mV less positive potential shift in contrast to bare GCE. Furthermore, the SAM modified electrode selectively determines G in the presence of high concentration of adenine (A). In differential pulse voltammetry measurements, the oxidation current response of G was increased linearly in the concentration range of 10 to 100 μM, and a detection limit was found to be 3×10(-8)M (signal/noise=3).
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Affiliation(s)
- A John Jeevagan
- Department of Chemistry, Gandhigram Rural Institute, Gandhigram, Dindigul 624 302, India
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Balraj C, Elango KP. Spectroscopic studies on the intermolecular charge transfer interaction of Fe(II)- and Fe(III)-phthalocyanines with 2,3,5,6-tetrachloro-1,4-benzoquinone and its application in colorimetric sensing of amino acids and amines. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 86:44-50. [PMID: 22074888 DOI: 10.1016/j.saa.2011.09.054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 09/17/2011] [Accepted: 09/27/2011] [Indexed: 05/31/2023]
Abstract
The interactions of Fe(II)Pc and Fe(III)Pc with π-acceptor 2,3,5,6-tetrachloro-1,4-benzoquinone (p-chloranil, p-CHL) have been investigated spectroscopically (UV/vis and FT-IR) and spectrofluorimetrically at three different temperatures. The stoichiometry of the complexes was found to be 1:1. The results of electronic spectral studies indicated that the formation constant for Fe(II)Pc-p-CHL system is found to be higher than that for Fe(III)Pc-p-CHL system. This observation is well supported by the results of fluorescence quenching studies and the association constants calculated for Fe(II)Pc-p-CHL system is 4.2 × 10(3) mol L(-1) and that for Fe(III)Pc-p-CHL system is 2.2 × 10(3) mol L(-1). The data are discussed in terms of physico-chemical parameters viz. molar extinction coefficient, oscillator strength, dipole moment, ionization potential, dissociation energy and thermodynamic parameters. The results indicated that the formation of π-π CT complex is spontaneous and endothermic. Preliminary studies indicated that the CT complex can effectively be used as a colorimetric agent for sensing amino acids and amines.
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Affiliation(s)
- Chellamuthu Balraj
- Department of Chemistry, Gandhigram Rural Institute (Deemed University), Gandhigram 624 302, India
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17
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Coates M, Antunes E, Nyokong T. Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424610002471] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
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Affiliation(s)
- Megan Coates
- Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa
| | - Edith Antunes
- Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa
| | - Tebello Nyokong
- Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa
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18
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Fabrication of conducting polymer-gold nanoparticles film on electrodes using monolayer protected gold nanoparticles and its electrocatalytic application. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.06.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Lokesh KS, De Wael K, Adriaens A. Self-assembled supramolecular array of polymeric phthalocyanine on gold for the determination of hydrogen peroxide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:17665-17673. [PMID: 20961064 DOI: 10.1021/la102740s] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This Article describes for the first time the formation of a supramolecular self-assembled monolayer of polymeric phthalocyanine (poly(CuPc)) onto a gold substrate. The latter is established through the interaction of the cyano group, belonging to the poly(CuPc), with the metal substrate. The functionalized gold substrate was characterized using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and electrochemical methods. Results clearly demonstrated the interaction between gold and the nitrogen atom of cyano group and showed at the same time the formation of a completely covered polymeric monolayer on the gold surface. In addition, the modified gold surface seems to exhibit a reversible redox behavior and is found to act as an electronic conductor, which allows rapid electron transfer. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)(6)](3-/4-) as a redox couple revealed that the modified electrode showed a much lower electron transfer resistance compared with bare gold. In addition, the modified electrode is found to catalyze the H(2)O(2) reduction very effectively, showing a catalytic current that varies linearly with the peroxide concentration in the range of 0.35 to 70 μM with a detection limit of 0.25 μM.
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Affiliation(s)
- Koodlur S Lokesh
- Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12, 9000 Ghent, Belgium
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Xiao J, Zhang Z, Wu D, Routaboul L, Braunstein P, Doudin B, Losovyj YB, Kizilkaya O, Rosa LG, Borca CN, Gruverman A, Dowben PA. The interface bonding and orientation of a quinonoid zwitterion. Phys Chem Chem Phys 2010; 12:10329-40. [PMID: 20577691 DOI: 10.1039/c003996a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have investigated the interaction and orientation of a strongly dipolar zwitterionic p-benzoquinonemonoimine-type molecule, with a large intrinsic dipole of 10 Debye, on both conducting and on polar insulating substrates. Specifically, we deposited (6Z)-4-(butylamino)-6-(butyliminio)-3-oxocyclohexa-1,4-dien-1-olate C(6)H(2)([horiz bar, triple dot above]NHR)(2)([horiz bar, triple dot above]O)(2) where R = n-C(4)H(9), on both gold and ferroelectric lithium niobate surfaces. An influence of both transient and static electric dipoles on the zwitterionic adsorbate has been observed. For adsorption on gold, we find that the molecule bonds to the surface through the nitrogen atoms, forming films that remain fairly uniform down to thicknesses in the 1 nm range. Adsorption of this zwitterionic compound from solution on insulating, periodically poled ferroelectric lithium niobate substrates, showed preferential adsorption on one type of ferroelectric domain. For both gold and the lithium niobate substrates, the zwitterion adopts a preferential orientation with the plane of its "C(6) core" along the surface normal. This simplified geometry of strong dipole alignment provides a symmetry simplification allowing better identification of the vibrational modes responsible for Frank-Condon scattering revealed in the fine spectroscopic signature in the photoemission spectrum.
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Affiliation(s)
- Jie Xiao
- Dept. of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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Chauke V, Matemadombo F, Nyokong T. Remarkable sensitivity for detection of bisphenol A on a gold electrode modified with nickel tetraamino phthalocyanine containing Ni-O-Ni bridges. JOURNAL OF HAZARDOUS MATERIALS 2010; 178:180-186. [PMID: 20122800 DOI: 10.1016/j.jhazmat.2010.01.061] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 05/28/2023]
Abstract
This work reports the electrocatalysis of bisphenol A on Ni(II) tetraamino metallophthalocyanine (NiTAPc) polymer modified gold electrode containing Ni-O-Ni bridges (represented as Ni(OH)TAPc). The Ni(II)TAPc films were electro-transformed in 0.1 mol L(-1) NaOH aqueous solution to form 'O-Ni-O oxo bridges', forming poly-n-Ni(OH)TAPc (where n is the number of polymerising scans). poly-30-Ni(OH)TAPc, poly-50-Ni(OH)TAPc, poly-70-Ni(OH)TAPc and poly-90-Ni(OH)TAPc films were investigated. The polymeric films were characterised by electrochemical impedance spectroscopy and the charge transfer resistance (R(CT)) values increased with film thickness. The best catalytic activity for the detection of bisphenol A was on poly-70-Ni(OH)TAPc. Electrode resistance to passivation improved with polymer thickness. The electrocatalytic behaviour of bisphenol A was compared to that of p-nitrophenol in terms of electrode passivation and regeneration. The latter was found to passivate the electrode less than the former. The poly-70-Ni(OH)TAPc modified electrode could reliably detect bisphenol A in a concentration range of 7x10(-4) to 3x10(-2)mol L(-1) with a limit of detection of 3.68x10(-9)mol L(-1). The sensitivity was 3.26x10(-4)A mol(-1) L cm(-2).
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Affiliation(s)
- Vongani Chauke
- Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa
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Sivanesan A, John S. Highly Sensitive Electrochemical Sensor for Nitric Oxide Using the Self-Assembled Monolayer of 1,8,15,22-Tetraaminophthalocyanatocobalt(II) on Glassy Carbon Electrode. ELECTROANAL 2010. [DOI: 10.1002/elan.200900443] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sivanesan A, John SA. Adsorption thermodynamics and kinetics study for the self-assembly of 1,8,15,22-tetraaminophthalocyanatocobalt(II) on glassy carbon surface. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2009.07.081] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Electrochemical and spectral studies of self-assembled monolayer of 1,8,15,22-tetraaminophthalocyanatocobalt(II) on indium tin oxide surface. J Electroanal Chem (Lausanne) 2009. [DOI: 10.1016/j.jelechem.2009.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Sivanesan A, John S. Selective Electrochemical Epinephrine Sensor Using Self-Assembled Monomolecular Film of 1,8,15,22-Tetraaminophthalocyanatonickel(II) on Gold Electrode. ELECTROANAL 2008. [DOI: 10.1002/elan.200804331] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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