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Mulkapuri S, Siddikha A, Ravi A, Saha P, Kumar AV, Boodida S, Vithal M, Das SK. Electrocatalytic Hydrogen Evolution by a Uranium(VI) Polyoxometalate: an Environmental Toxin for Sustainable Energy Generation. Inorg Chem 2023; 62:19664-19676. [PMID: 37967464 DOI: 10.1021/acs.inorgchem.3c03018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2023]
Abstract
The uranyl ion (UO2)2+, a uranium nuclear waste, is one of the serious contaminants in our ecosystem because of its radioactivity, relevant human activities, and highly mobile and complex nature of living cells. In this article, we have reported the synthesis and structural characterization of an uranyl cation-incorporated polyoxometalate (POM) compound, K10[{K4(H2O)6}{UO2}2(α-PW9O34)2]·13H2O (1), in which the uranyl cations are complexed with an in situ generated [α-PW9O34]9- cluster. Single-crystal X-ray diffraction (SCXRD) analysis of compound 1 reveals that the uranyl-potassium complex cationic species, [{K4(H2O)6}{UO2}2]8+, is sandwiched by two [α-PW9O34]9- clusters resulting in a Dawson type of POM. Compound 1 was further characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis and infrared (IR), Raman, electronic absorption, and solid-state photoluminescence spectral studies. IR stretching vibrations at 895 and 856 cm-1 and the Raman signature peak at 792 cm-1 in the IR and Raman spectra of compound 1 primarily confirm the presence of a trans-[O═U═O]2+ ion. The solid-state photoluminescence spectrum of 1 exhibits a typical vibronic structure, resulting from symmetrical vibrations of [O═U═O]2+ bands, corresponding to the electronic transitions of S11 → S10 and S10 → S0υ (υ = 0-3). Interestingly, title compound 1 shows efficient electrocatalytic hydrogen evolution by water reduction with low Tafel slope values of 186.59 and 114.83 mV dec-1 at 1 mA cm-2 along with optimal Faradaic efficiency values of 82 and 87% at neutral pH and in acidic pH 3, respectively. Detailed electrochemical analyses reveal that the catalytic hydrogen evolution reaction (HER) activity mediated by compound 1 is associated with the UVI/UV redox couple of the POM. The microscopic as well as routine spectral analyses of postelectrode samples and controlled experiments have confirmed that compound 1 behaves like a true molecular electrocatalyst for the HER. To our knowledge, this is the first paradigm of a uranium-containing polyoxometalate that exhibits electrocatalytic water reduction to molecular H2. In a nutshell, an environmental toxin (a uranium-oxo compound) has been demonstrated to be utilized as an efficient electrocatalyst for hydrogen generation from water, a green approach of sustainable energy production.
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Affiliation(s)
- Sateesh Mulkapuri
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
| | - Asha Siddikha
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
- Department of Chemistry, JNTUH University College of Engineering, Science and Technology, Hyderabad 500085, India
- Department of Chemistry, Osmania University, Hyderabad 500 007, India
| | - Athira Ravi
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
| | - Pinki Saha
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
| | - Avulu Vinod Kumar
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
| | - Sathyanarayana Boodida
- Department of Chemistry, JNTUH University College of Engineering, Science and Technology, Hyderabad 500085, India
| | - Muga Vithal
- Department of Chemistry, Osmania University, Hyderabad 500 007, India
| | - Samar K Das
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, India
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Mulkapuri S, Ravi A, Nasani R, Kurapati SK, Das SK. Barrel-Shaped-Polyoxometalates Exhibiting Electrocatalytic Water Reduction at Neutral pH: A Synergy Effect. Inorg Chem 2022; 61:13868-13882. [PMID: 36006778 DOI: 10.1021/acs.inorgchem.2c01811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two copper-based barrel-shaped polyoxometalates (POMs), namely, [{H3O}4{Na6(H2O)22}][{CuI (H2O)3}2{CuII (H2O)}3{B-α-BiIIIWVI9O33}2]·7H2O (NaCu-POM) and Li4[{NH4}2{H3O}3{Li(H2O)5}][{CuII(SH)}{(CuIICuI1.5)(B-α-BiIIIWVI9O33)}2]·9H2O (LiCu-POM) have been synthesized and structurally characterized. The single-crystal X-ray diffraction analyses of NaCu-POM and LiCu-POM reveal the presence of penta- and hexa-nuclear copper wheels per formula units, respectively; these copper wheels are sandwiched between two lacunary Keggin anions {B-α-BiIIIWVI9O33}9- (BiW9) to form the barrel-shaped title POM compounds. In both the compounds NaCu-POM and LiCu-POM, the mixed-valent copper centers are present in their respective penta- and hexa-nuclear copper wheels, established by X-ray photoelectron spectroscopy (XPS) as well as by bond valence sum (BVS) calculations. Compound LiCu-POM additionally shows the presence of a sulfhydryl ligand (SH-), coordinated to one of the copper centers of its {Cu6}-wheel, that is expected to be generated from the in situ reduction of sulfate anion present in the concerned reaction mixture (lithium-ion in ammonia solution may be the reducing agent). Interestingly, the title compounds, NaCu-POM and LiCu-POM exhibit an efficient electrocatalytic hydrogen evolution reaction (HER) by reducing water at neutral pH. Detailed electrochemical studies including controlled experiments indicate that the active sites for this electrocatalysis are the W(VI) centers of the title compounds, not the copper centers. However, a relevant tri-lacunary Keggin cluster anion {PVWVI9O33}7- (devoid of copper ion) does not show comparable HER as shown by the title compounds. The intra-cluster cooperative interactions of the mixed-valent copper centers (CuII/CuI) with the tungsten centers (W6+) make the overall system electrocatalytically active toward water reduction to molecular hydrogen at neutral pH. High Faradaic efficiencies (89 and 92%) and turnover frequencies (1.598 s-1 and 1.117 s-1) make the title compounds NaCu-POM and LiCu-POM efficient catalysts toward electrochemical water reduction to molecular hydrogen.
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Affiliation(s)
- Sateesh Mulkapuri
- School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
| | - Athira Ravi
- School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
| | - Rajendar Nasani
- School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
| | - Sathish Kumar Kurapati
- School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India.,Department of Chemistry, Chaitanya Bharathi Institute of Technology Hyderabad, Gandipet, Hyderabad 500075, India
| | - Samar K Das
- School of Chemistry, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
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Yang ZC, Cai HX, Bacha RUS, Ding SD, Pan QJ. Theoretical Investigation of Catalytic Water Splitting by the Arene-Anchored Actinide Complexes. Inorg Chem 2022; 61:11715-11724. [PMID: 35838526 DOI: 10.1021/acs.inorgchem.2c01379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Actinide complexes, which could enable the electrocatalytic H2O reduction, are not well documented because of the fact that actinide-containing catalysts are precluded by extremely stable actinyl species. Herein, by using relativistic density functional theory calculations, the arene-anchored trivalent actinide complexes (Me,MeArO)3ArAn (marked as [AnL]) with desirable electron transport between metal and ligand arene are investigated for H2 production. The metal center is changed from Ac to Pu. Electron-spin density calculations reveal a two-electron oxidative process (involving high-valent intermediates) for complexes [AnL] (An = P-Pu) along the catalytic pathway. The electrons are provided by both the actinide metal and the arene ring of ligand. This is comparable to the previously reported uranium catalyst (Ad,MeArO)3mesU (Ad = adamantine and mes = mesitylene). From the thermodynamic and kinetic perspectives, [PaL] offers appreciably lower reaction energies for the overall catalytic cycle than other actinide complexes. Thus, the protactinium complex tends to be the most reactive for H2O reduction to produce H2 and has the advantage of its experimental accessibility.
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Affiliation(s)
- Zhi-Ce Yang
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
| | - Hong-Xue Cai
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
| | - Raza Ullah Shah Bacha
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
| | - Song-Dong Ding
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Qing-Jiang Pan
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
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Ghosh S, Srivastava AK, Sharma M, Pal S. Chiral Diuranyl(VI) Complexes and Their Catecholase Activities: Experimental and Theoretical Insights. ChemistrySelect 2022. [DOI: 10.1002/slct.202200293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sabari Ghosh
- School of Chemistry University of Hyderabad Hyderabad 500046 India
| | | | - Manju Sharma
- School of Chemistry University of Hyderabad Hyderabad 500046 India
| | - Samudranil Pal
- School of Chemistry University of Hyderabad Hyderabad 500046 India
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Srivastava AK, Mondal A, Konar S, Pal S. A tetra Co(II/III) complex with an open cubane Co 4O 4 core and square-pyramidal Co(II) and octahedral Co(III) centres: bifunctional electrocatalytic activity towards water splitting at neutral pH. Dalton Trans 2022; 51:4510-4521. [PMID: 35234225 DOI: 10.1039/d1dt04086c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The reaction of 2,6-diformyl-4-methylphenol, 4-methoxybenzoylhydrazine and Co(OAc)2·4H2O in 1 : 2 : 2 mole ratio in methanol under aerobic conditions produced in 61% yield a tetranuclear complex having the molecular formula [CoIICoIII(μ-OAc)(μ3-OH)(μ-L)]2 where OAc- and L3- represent acetate and N',N''-(5-methyl-2-oxido-1,3-phenylene)bis(methan-1-yl-1-ylidene)bis(4-methoxybenzoylhydrazonate), respectively. The elemental analysis and the mass spectrometric data confirmed the molecular formula of the complex. It is electrically non-conducting and paramagnetic. The complex crystallized as acetonitrile solvate. The X-ray structure shows that each Co(II) centre has a distorted square-pyramidal NO4 coordination sphere, while each Co(III) centre is in a distorted octahedral NO5 environment. The four metal atoms and the four bridging O-atoms form an open cubane type Co4O4 motif. In the crystal lattice, self-assembly of the solvated complex via intermolecular O-H⋯O interaction leads to a two-dimensional network structure. The infrared and electronic spectroscopic features of the complex are consistent with its molecular structure. Cryomagnetic measurements together with theoretical calculations suggest the presence of easy-axis anisotropy for the square-pyramidal Co(II) centres. The complex is redox-active and displays metal centred oxidation and reduction responses on the anodic and cathodic sides, respectively, of the Ag/AgCl electrode. Bifunctional heterogeneous electrocatalytic activity of the complex towards O2 and H2 evolution reactions (OER and HER) in neutral aqueous medium has been explored in detail.
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Affiliation(s)
| | - Arpan Mondal
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, India
| | - Sanjit Konar
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, India
| | - Samudranil Pal
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
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Hartline D, Meyer K. From Chemical Curiosities and Trophy Molecules to Uranium-Based Catalysis: Developments for Uranium Catalysis as a New Facet in Molecular Uranium Chemistry. JACS AU 2021; 1:698-709. [PMID: 34467327 PMCID: PMC8395704 DOI: 10.1021/jacsau.1c00082] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Indexed: 05/16/2023]
Abstract
Catalysis remains one of the final frontiers in molecular uranium chemistry. Depleted uranium is mildly radioactive, continuously generated in large quantities from the production and consumption of nuclear fuels and accessible through the regeneration of "uranium waste". Organometallic complexes of uranium possess a number of properties that are appealing for applications in homogeneous catalysis. Uranium exists in a wide range of oxidation states, and its large ionic radii support chelating ligands with high coordination numbers resulting in increased complex stability. Its position within the actinide series allows it to involve its f-orbitals in partial covalent bonding; yet, the U-L bonds remain highly polarized. This causes these bonds to be reactive and, with few exceptions, relatively weak, allowing for high substrate on/off rates. Thus, it is reasonable that uranium could be considered as a source of metal catalysts. Accordingly, uranium complexes in oxidation states +4, +5, and +6 have been studied extensively as catalysts in sigma-bond metathesis reactions, with a body of literature spanning the past 40 years. High-valent species have been documented to perform a wide variety of reactions, including oligomerization, hydrogenation, and hydrosilylation. Concurrently, electron-rich uranium complexes in oxidation states +2 and +3 have been proven capable of performing reductive small molecule activation of N2, CO2, CO, and H2O. Hence, uranium's ability to activate small molecules of biological and industrial relevance is particularly pertinent when looking toward a sustainable future, especially due to its promising ability to generate ammonia, molecular hydrogen, and liquid hydrocarbons, though the advance of catalysis in these areas is in the early stages of development. In this Perspective, we will look at the challenges associated with the advance of new uranium catalysts, the tools produced to combat these challenges, the triumphs in achieving uranium catalysis, and our future outlook on the topic.
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Behera N, Sethi S. Unprecedented Catalytic Behavior of Uranyl(VI) Compounds in Chemical Reactions. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Nabakrushna Behera
- School of Chemistry Sambalpur University Jyoti Vihar – 768019 Sambalpur Odisha India
| | - Sipun Sethi
- School of Chemistry Sambalpur University Jyoti Vihar – 768019 Sambalpur Odisha India
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Bhunia P, Ghosh S, Gomila RM, Frontera A, Ghosh A. Reaction of Cu(II) Chelates with Uranyl Nitrate to Form a Coordination Complex or H-Bonded Adduct: Experimental Observations and Rationalization by Theoretical Calculations. Inorg Chem 2020; 59:15848-15861. [PMID: 33078932 DOI: 10.1021/acs.inorgchem.0c02338] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Four new heterometallic Cu(II)-U(VI) species, [{(CuL1)(CH3CN)}UO2(NO3)2] (1), [{(CuL2)(CH3CN)}UO2(NO3)2] (2), [{(CuL3)(H2O)}UO2(NO3)2] (3), and [UO2(NO3)2(H2O)2]·2[CuL4]·H2O (4), were synthesized using four different metalloligands ([CuL1], [CuL2], [CuL3], and [CuL4], respectively) derived from four unsymmetrically dicondensed N,O-donor Schiff bases. Single-crystal structural analyses revealed that complexes 1, 2, and 3 have a discrete dinuclear [Cu-UO2] core in which one metalloligand, [CuL], is connected to the uranyl moiety via a double phenoxido bridge. Two chelating nitrate ions complete the octa-coordination around uranium. Species 4 is a cocrystal, where a uranyl nitrate dihydrate is sandwiched between two metalloligands [CuL4] by the formation of strong hydrogen bonds between the H atoms of the coordinated water molecules to U(VI) and the O atoms of [CuL4]. Spectrophotometric titrations of these four metalloligands with uranyl nitrate dihydrate in acetonitrile showed a well-anchored isosbestic point between 300 and 500 nm in all cases, conforming with the coordination of [CuL1], [CuL2], [CuL3], and the H-bonding interaction of [CuL4] with UO2(NO3)2. This behavior of [CuL4] was utilized to selectively bind metal ions (e.g., Mg2+, Ca2+, Sr2+, Ba2+, and La3+) in the presence of UO2(NO3)2·2H2O in acetonitrile. The formation of these Cu(II)-U(VI) species in solution was also evaluated by steady-state fluorescence quenching experiments. The difference in the coordination behavior of these metalloligands toward [UO2(NO3)2(H2O)2] was studied by density functional theory calculations. The lower flexibility of the ethylenediamine ring and a large negative binding energy obtained from the evaluation of H bonds and supramolecular interactions between [CuL4] and [UO2(NO3)2(H2O)2] corroborate the formation of cocrystal 4. A very good linear correlation (r2 = 0.9949) was observed between the experimental U═O stretching frequencies and the strength of the equatorial bonds that connect the U atom to the metalloligand.
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Affiliation(s)
- Pradip Bhunia
- Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, West Bengal, India
| | - Soumavo Ghosh
- Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, West Bengal, India
| | - Rosa M Gomila
- Departament de Química, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma de Mallorca, Baleares, Spain
| | - Antonio Frontera
- Departament de Química, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma de Mallorca, Baleares, Spain
| | - Ashutosh Ghosh
- Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, West Bengal, India.,Rani Rashmoni Green University, Hooghly 712410, West Bengal, India
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Absalan Y, Gholizadeh M, Butusov L, Bratchikova I, Kopylov V, Kovalchukova O. Titania nanotubes (TNTs) prepared through the complex compound of gallic acid with titanium; examining photocatalytic degradation of the obtained TNTs. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.02.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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WITHDRAWN: Titania nanotubes (TNTs) prepared through the complex compound of gallic acid with titanium; examining photocatalytic degradation of the obtained TNTs. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Oligonuclear Actinoid Complexes with Schiff Bases as Ligands-Older Achievements and Recent Progress. Int J Mol Sci 2020; 21:ijms21020555. [PMID: 31952278 PMCID: PMC7027032 DOI: 10.3390/ijms21020555] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 01/09/2023] Open
Abstract
Even 155 years after their first synthesis, Schiff bases continue to surprise inorganic chemists. Schiff-base ligands have played a major role in the development of modern coordination chemistry because of their relevance to a number of interdisciplinary research fields. The chemistry, properties and applications of transition metal and lanthanoid complexes with Schiff-base ligands are now quite mature. On the contrary, the coordination chemistry of Schiff bases with actinoid (5f-metal) ions is an emerging area, and impressive research discoveries have appeared in the last 10 years or so. The chemistry of actinoid ions continues to attract the intense interest of many inorganic groups around the world. Important scientific challenges are the understanding the basic chemistry associated with handling and recycling of nuclear materials; investigating the redox properties of these elements and the formation of complexes with unusual metal oxidation states; discovering materials for the recovery of trans-{UVIO2}2+ from the oceans; elucidating and manipulating actinoid-element multiple bonds; discovering methods to carry out multi-electron reactions; and improving the 5f-metal ions’ potential for activation of small molecules. The study of 5f-metal complexes with Schiff-base ligands is a currently “hot” topic for a variety of reasons, including issues of synthetic inorganic chemistry, metalosupramolecular chemistry, homogeneous catalysis, separation strategies for nuclear fuel processing and nuclear waste management, bioinorganic and environmental chemistry, materials chemistry and theoretical chemistry. This almost-comprehensive review, covers aspects of synthetic chemistry, reactivity and the properties of dinuclear and oligonuclear actinoid complexes based on Schiff-base ligands. Our work focuses on the significant advances that have occurred since 2000, with special attention on recent developments. The review is divided into eight sections (chapters). After an introductory section describing the organization of the scientific information, Sections 2 and 3 deal with general information about Schiff bases and their coordination chemistry, and the chemistry of actinoids, respectively. Section 4 highlights the relevance of Schiff bases to actinoid chemistry. Sections 5–7 are the “main menu” of the scientific meal of this review. The discussion is arranged according the actinoid (only for Np, Th and U are Schiff-base complexes known). Sections 5 and 7 are further arranged into parts according to the oxidation states of Np and U, respectively, because the coordination chemistry of these metals is very much dependent on their oxidation state. In Section 8, some concluding comments are presented and a brief prognosis for the future is attempted.
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