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Singh P, Zeller M, Mezei G. Supramolecular Binding of Phosphonate Dianions by Nanojars and Nanojar Clamshells. Inorg Chem 2024; 63:14216-14230. [PMID: 39023277 PMCID: PMC11289757 DOI: 10.1021/acs.inorgchem.4c02386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 07/03/2024] [Accepted: 07/11/2024] [Indexed: 07/20/2024]
Abstract
Despite the widespread use of phosphonates (RPO32-) in various agricultural, industrial, and household applications and the ensuing eutrophication of polluted water bodies, the capture of phosphonate ions by molecular receptors has been scarcely studied. Herein, we describe a novel approach to phosphonate binding using chemically and thermally robust supramolecular coordination assemblies of the formula [RPO3⊂{cis-CuII(μ-OH)(μ-pz)}n]2- (Cun; n = 27-31; pz = pyrazolate ion, C3H3N2-; R = aliphatic or aromatic group). The neutral receptors, termed nanojars, strongly bind phosphonate anions by a multitude of hydrogen bonds within their highly hydrophilic cavities. These nanojars can be synthesized either directly from their constituents or by depolymerization of [trans-CuII(μ-OH)(μ-pz)]∞ induced by phosphonate anions. Electrospray-ionization mass spectrometry, UV-vis and variable-temperature, paramagnetic 1H and 31P NMR spectroscopy, single-crystal X-ray diffraction, along with chemical stability studies toward NH3 and Ba2+ ions, and thermal stability studies in solution are employed to explore the binding of various phosphonate ions by nanojars. Crystallographic studies of 12 different nanojars offer unprecedented structural characterization of host-guest complexes with doubly charged RPO32- ions and reveal a new motif in nanojar chemistry, nanojar clamshells, which consist of phosphonate anion-bridged pairs of nanojars and double the phosphonate-binding capacity of nanojars.
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Affiliation(s)
- Pooja Singh
- Department
of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Matthias Zeller
- Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gellert Mezei
- Department
of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
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2
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Al Isawi WA, Hartman CK, Singh P, Zeller M, Mezei G. Chromate Incarceration by Nanojars and Its Removal from Water by Liquid-Liquid Extraction. Inorg Chem 2023; 62:5716-5728. [PMID: 36961999 DOI: 10.1021/acs.inorgchem.3c00262] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
The unprecedented liquid-liquid extraction of the dinegative chromate ion (CrO42-) from neutral aqueous solutions into aliphatic hydrocarbon solvents using nanojars as extraction agents is demonstrated. Transferring chromate from water into an organic solvent is extremely challenging due to its large hydration energy (ΔGh° = -950 kJ/mol) and strong oxidizing ability. Owing to their highly hydrophilic anion binding pockets lined by a multitude of hydrogen bond donor OH groups, neutral nanojars of the formula [cis-CuII(μ-OH)(μ-4-Rpz)]n (n = 27-33; pz = pyrazolate anion; R = H or n-octyl) strongly bind the CrO42- ion and efficiently transfer it from water into n-heptane or C11 - C13 isoalkanes (when R = n-octyl). The extracted chromate can easily be recovered from the organic layer by stripping with an aqueous acid solution. Electrospray ionization mass spectrometric, UV-vis and paramagnetic 1H NMR spectroscopic, X-ray crystallographic, and thermal stability studies in solution and chemical stability studies toward NH3, methanol, and Ba2+ ions are employed to explore the binding of the CrO42- ion by nanojars. Titration of carbonate nanojars [CO3 ⊂ {Cu(OH)(pz)}n]2- with H2CrO4 leads to anion exchange and the formation of chromate nanojars [CrO4 ⊂ {Cu(OH)(pz)}n]2-. Details of chromate binding by H-bonding based on single-crystal structures of (Bu4N)2[CrO4 ⊂ {Cu(OH)(pz)}28], four pseudopolymorphs of (Bu4N)2[CrO4 ⊂ {Cu(OH)(pz)}31], and also the methoxy-substituted derivative (Bu4N)2[CrO4 ⊂ {Cu31(OH)30(OCH3)(pz)31}] are presented.
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Affiliation(s)
- Wisam A Al Isawi
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Christian K Hartman
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Pooja Singh
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Matthias Zeller
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
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3
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Al Isawi WA, Jawor ML, Hartman CK, Mezei G. Evaluation of the interaction of nanojars with biomolecules found in human body fluids. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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4
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Al Isawi WA, Zeller M, Mezei G. Supramolecular Incarceration and Extraction of Tetrafluoroberyllate from Water by Nanojars. Inorg Chem 2022; 61:8611-8622. [PMID: 35617675 DOI: 10.1021/acs.inorgchem.2c01198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The previously unexplored noncovalent binding of the highly toxic tetrafluoroberyllate anion (BeF42-) and its extraction from water into organic solvents are presented. Nanojars resemble anion-binding proteins in that they also possess an inner anion binding pocket lined by a multitude of H-bond donors (OH groups), which wrap around the incarcerated anion and completely isolate it from the surrounding medium. The BeF4-binding propensity of [BeF4⊂{CuII(OH)(pz)}n]2- (pz = pyrazolate; n = 27-32) nanojars of different sizes is investigated using an array of techniques including mass spectrometry, paramagnetic 1H, 9Be, and 19F NMR spectroscopy, and X-ray crystallography, along with thermal stability studies in solution and chemical stability studies toward acidity and Ba2+ ions. The latter is found to be unable to precipitate the insoluble BaBeF4 from nanojar solutions, indicating a very strong binding of the BeF42- anion by nanojars. 9Be and 19F NMR spectroscopy allows for the unprecedented direct probing of the incarcerated anion in a nanojar and, along with 1H NMR studies, reveals the fluxional structure of nanojars and their inner anion-binding pockets. Single-crystal X-ray diffraction provides the crystal and molecular structures of (Bu4N)2[BeF4⊂{Cu(OH)(pz)}32], which contains a novel Cux-ring combination (x = 9 + 14 + 9), (Bu4N)2[BeF4⊂{Cu(OH)(pz)}8+14+9], and (Bu4N)2[BeF4⊂{Cu(OH)(pz)}6+12+10] and offers detailed structural parameters related to the supramolecular binding of BeF42- in these nanojars. The extraction of BeF42- from water into organic solvents, including the highly hydrophobic solvent n-heptane, demonstrates that nanojars are efficient binding and extracting agents not only for oxoanions but also for fluoroanions.
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Affiliation(s)
- Wisam A Al Isawi
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Matthias Zeller
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
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5
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Mitchell M, Liyana Gunawardana VW, Ramakrishna G, Mezei G. Pyrene-Functionalized Fluorescent Nanojars: Synthesis, Mass Spectrometric, and Photophysical Studies. ACS OMEGA 2021; 6:33180-33191. [PMID: 34901669 PMCID: PMC8656208 DOI: 10.1021/acsomega.1c05619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
Nanojars are a class of supramolecular coordination complexes based on pyrazolate, Cu2+, and OH- ions that self-assemble around highly hydrophilic anions and serve as efficient anion binding and extraction agents. In this work, the synthesis, characterization, and photophysical properties of pyrene-functionalized fluorescent nanojars are presented. Three pyrene derivatives, 4-(pyren-1-yl)pyrazole (HL1), 4-(5-(pyren-1-yl)pent-4-yn-1-yl)pyrazole (HL2), and 4-(3-(pyrazol-4-yl)propyl)-1-(pyren-1-yl)-1,2,3-triazole (HL3), and the corresponding nanojars were synthesized and characterized using nuclear magnetic resonance spectroscopy and mass spectrometry. Electronic absorption, steady-state, and time-resolved fluorescence measurements were carried out to understand the interaction between the pyrene fluorophore and copper nanojars. Optical absorption measurements have shown minor ground state interaction between the fluorophore and nanojars. The fluorescence of pyrene is significantly quenched when attached to nanojars, suggesting strong contribution from the paramagnetic Cu2+ ions. Significant static quenching is observed in the case of L1, when pyrene is directly bound to the nanojar, whereas in the case of L2 and L3, when pyrene is attached to the nanojars using flexible tethers, both static and dynamic quenching are observed.
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Affiliation(s)
- Melanie
M. Mitchell
- Department of Chemistry, Western
Michigan University, Kalamazoo, Michigan 49008, USA
| | | | - Guda Ramakrishna
- Department of Chemistry, Western
Michigan University, Kalamazoo, Michigan 49008, USA
| | - Gellert Mezei
- Department of Chemistry, Western
Michigan University, Kalamazoo, Michigan 49008, USA
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6
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Al Isawi WA, Salome AZ, Ahmed BM, Zeller M, Mezei G. Selective binding of anions by rigidified nanojars: sulfate vs. carbonate. Org Biomol Chem 2021; 19:7641-7654. [PMID: 34524323 DOI: 10.1039/d1ob01318a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Selective binding and transport of highly hydrophilic anions is ubiquitous in nature, as anion binding proteins can differentiate between similar anions with over a million-fold efficiency. While comparable selectivity has occasionally been achieved for certain anions using small, artificial receptors, the selective binding of certain anions, such as sulfate in the presence of carbonate, remains a very challenging task. Nanojars of the formula [anion⊂{Cu(OH)(pz)}n]2- (pz = pyrazolate; n = 27-33) are totally selective for either CO32- or SO42- over anions such as NO3-, ClO4-, BF4-, Cl-, Br- and I-, but cannot differentiate between the two. We hypothesized that rigidification of the nanojar outer shell by tethering pairs of pyrazole moieties together will restrict the possible orientations of the OH hydrogen-bond donor groups in the anion-binding cavity of nanojars, similarly to anion-binding proteins, and will lead to selectivity. Indeed, by using either homoleptic or heteroleptic nanojars of the general formula [anion⊂Cun(OH)n(L2-L6)y(pz)n-2y]2- (n = 26-31) based on a series of homologous ligands HpzCH2(CH2)xCH2pzH (x = 0-4; H2L2-H2L6), selectivity for carbonate (with L2 and with L4-L6/pz mixtures) or for sulfate (with L3) has been achieved. The synthesis of new ligands H2L3, H2L4 and H2L5, X-ray crystal structures of H2L4 and the tetrahydropyranyl-protected derivatives (THP)2L4 and (THP)2L5, synthesis and characterization by electrospray-ionization mass spectrometry (ESI-MS) of carbonate- and sulfate-nanojars derived from ligands H2L2-H2L6, as well as detailed selectivity studies for CO32-vs. SO42- using these novel nanojars are presented.
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Affiliation(s)
- Wisam A Al Isawi
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, USA.
| | - Austin Z Salome
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, USA.
| | - Basil M Ahmed
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, USA.
| | - Matthias Zeller
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, USA.
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7
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Al Isawi WA, Zeller M, Mezei G. Capped Nanojars: Synthesis, Solution and Solid-State Characterization, and Atmospheric CO 2 Sequestration by Selective Binding of Carbonate. Inorg Chem 2021; 60:13479-13492. [PMID: 34448565 DOI: 10.1021/acs.inorgchem.1c01826] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nanojars are a class of supramolecular anion-incarcerating coordination complexes that self-assemble from Cu2+ ions, pyrazole, and a strong base in the presence of highly hydrophilic anions. In this work, we show that if the strong base (e.g., NaOH or Bu4NOH) is replaced by a weak base such as a trialkylamine, capped nanojars of the formula [{Cu3(μ3-OH)(μ-pz)3L3}CO3⊂{Cu(μ-OH)(μ-pz)}n] (pz = pyrazolate anion; L = neutral donor molecule; n = 27-31) are obtained instead of the conventional nanojars. Yet, to obtain capped nanojars, the conjugate acid side product originating from the weak base must be separated by transferring it to water either by precipitation of the water-insoluble capped nanojars or by liquid-liquid extraction. Full characterization using electrospray ionization mass spectrometry, UV-vis and variable-temperature 1H NMR spectroscopy in solution, and single-crystal X-ray diffraction, elemental analysis, and solubility studies in the solid state reveals similarities as well as drastic differences between capped nanojars and nanojars lacking the [Cu3(μ3-OH)(μ-pz)3L3]2+ cap. Acid-base reactivity studies demonstrate that capped nanojars are intermediates in the pH-controlled assembly-disassembly of nanojars. During the self-assembly of capped nanojars, CO2 is selectively sequestered from air in the presence of other atmospheric gases and converted to carbonate, the binding of which is selective in the presence of NO3-, ClO4-, BF4-, Cl-, and Br- ions.
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Affiliation(s)
- Wisam A Al Isawi
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Matthias Zeller
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
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8
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Al Isawi WA, Mezei G. Doubling the Carbonate-Binding Capacity of Nanojars by the Formation of Expanded Nanojars. Molecules 2021; 26:3083. [PMID: 34064130 PMCID: PMC8196769 DOI: 10.3390/molecules26113083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/12/2021] [Accepted: 05/19/2021] [Indexed: 11/16/2022] Open
Abstract
Anion binding and extraction from solutions is currently a dynamic research topic in the field of supramolecular chemistry. A particularly challenging task is the extraction of anions with large hydration energies, such as the carbonate ion. Carbonate-binding complexes are also receiving increased interest due to their relevance to atmospheric CO2 fixation. Nanojars are a class of self-assembled, supramolecular coordination complexes that have been shown to bind highly hydrophilic anions and to extract even the most hydrophilic ones, including carbonate, from water into aliphatic solvents. Here we present an expanded nanojar that is able to bind two carbonate ions, thus doubling the previously reported carbonate-binding capacity of nanojars. The new nanojar is characterized by detailed single-crystal X-ray crystallographic studies in the solid state and electrospray ionization mass spectrometric (including tandem MS/MS) studies in solution.
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Affiliation(s)
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, MI 49008, USA;
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9
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Chen JH, Wei D, Yang G, Ma JG, Cheng P. A systematic investigation of structural transformation in a copper pyrazolato system: a case study. Dalton Trans 2020; 49:1116-1123. [PMID: 31894791 DOI: 10.1039/c9dt04263f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Dissolution-recrystallization structural transformation (DRST) is a powerful tool to unravel unequivocally the mechanism of dynamic conversion processes, based on the structures of the initial reactants, final products and sometimes intermediates isolated from the reaction mixture. Herein, we illustrate the details of the conversion processes of (CuIpz)3 into [CuII(OH)pz]6 (pzH = 4-chloro-3,5-diphenylpyrazole) through DRSTs. Based on crystal structure determination and spectroscopic methods, the most encountered species, (CuIpz)3, is in equilibrium with (CuIpz)4 in solution with the tetramer becoming dominant at low temperature, indicating an entropy-controlled conversion between these two structural isomers. The CuI trimer/tetramer in solution further experiences an oxidation if exposed to the open air, resulting in the formation of a pentanuclear mixed-valence intermediate CuI3CuII2(OMe)2pz5 which can be isolated as single crystals at -20 °C and has been structurally characterized for the first time. The final product isolated from the solution is the fully oxidized hexanuclear [CuII(OMe)pz]6, which is easily transformed into [CuII(OH)pz]6 in the presence of humidity.
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Affiliation(s)
- Jing-Huo Chen
- Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China.
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10
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Al Isawi WA, Ahmed BM, Hartman CK, Seybold AN, Mezei G. Are nanojars unique to copper? Solution and solid state characterization of high-symmetry octanuclear nickel(II)-pyrazolate complexes. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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11
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Liyana Gunawardana VW, Mezei G. Amplification of impurity upon complex formation: how a 2% ligand impurity lowers the corresponding complex purity to 50%. NEW J CHEM 2018. [DOI: 10.1039/c8nj04176h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Statistical incorporation of small amounts of ligand impurities has devastating consequences on the purity of metal–organic complexes derived from the respective ligands.
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Affiliation(s)
| | - Gellert Mezei
- Department of Chemistry
- Western Michigan University
- Kalamazoo
- USA
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12
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Hartman CK, Mezei G. Mapping the Intricate Reactivity of Nanojars toward Molecules of Varying Acidity and Their Conjugate Bases Leading To Exchange of Pyrazolate Ligands. Inorg Chem 2017; 56:10609-10624. [DOI: 10.1021/acs.inorgchem.7b01593] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christian K. Hartman
- Department of Chemistry, Western Michigan University, Kalamazoo 49008, Michigan, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo 49008, Michigan, United States
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13
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Kirillova MV, Santos CIM, André V, Fernandes TA, Dias SSP, Kirillov AM. Self-assembly generation, structural features, and oxidation catalytic properties of new aqua-soluble copper(ii)-aminoalcohol derivatives. Inorg Chem Front 2017. [DOI: 10.1039/c6qi00553e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Multidentate aminoalcohols were applied as unexplored building blocks to generate two novel Cu(ii) coordination compounds that act as efficient catalysts for the mild and acid-promoter-free oxidation of C5–C8 cycloalkanes.
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Affiliation(s)
- Marina V. Kirillova
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Carla I. M. Santos
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Vânia André
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Tiago A. Fernandes
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Sara S. P. Dias
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Alexander M. Kirillov
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
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Ahmed BM, Mezei G. Accessing the inaccessible: discrete multinuclear coordination complexes and selective anion binding attainable only by tethering ligands together. Chem Commun (Camb) 2017; 53:1029-1032. [DOI: 10.1039/c6cc09197k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of tethers between ligands allows for the preparation of novel multimetallic complexes, not obtainable without tethers, and leads to unexpected properties, such as selective binding of the carbonate vs. sulfate anion by nanojars.
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Affiliation(s)
- Basil M. Ahmed
- Department of Chemistry
- Western Michigan University
- Kalamazoo
- USA
| | - Gellert Mezei
- Department of Chemistry
- Western Michigan University
- Kalamazoo
- USA
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15
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Surmann SA, Mezei G. Halogen-bonded network of trinuclear copper(II) 4-iodo-pyrazolate complexes formed by mutual breakdown of chloro-form and nanojars. Acta Crystallogr E Crystallogr Commun 2016; 72:1517-1520. [PMID: 27840698 PMCID: PMC5095823 DOI: 10.1107/s205698901601536x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/29/2016] [Indexed: 11/30/2022]
Abstract
Crystals of bis-(tetra-butyl-ammonium) di-μ3-chlorido--tris-(μ2-4-iodo-pyrazolato-κ2N:N')tris-[chlorido-cuprate(II)] 1,4-dioxane hemisolvate, (C16H36N)2[Cu3(C3H2IN2)3Cl5]·0.5C4H8O or (Bu4N)2[CuII3(μ3-Cl)2(μ-4-I-pz)3Cl3]·0.5C4H8O, were obtained by evaporating a solution of (Bu4N)2[{CuII(μ-OH)(μ-4-I-pz)} n CO3] (n = 27-31) nanojars in chloro-form/1,4-dioxane. The decomposition of chloro-form in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II) pyrazolate complex, and possibly CuII ions and free 4-iodo-pyrazole. CuII ions, in turn, act as catalyst for the accelerated decomposition of chloro-form, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II) pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4-R-pyrazoles (R = H, Cl, Br, Me), the [Cu3(μ-4-I-pz)3Cl3] core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes [mean length of I⋯Cl contacts = 3.48 (1) Å], leading to an extended two-dimensional, halogen-bonded network along (-110). The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent mol-ecules, which create further bridges via C-H⋯Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.
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Affiliation(s)
- Stuart A. Surmann
- Department of Chemistry, Western Michigan University, Kalamazoo, MI 49006
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, MI 49006
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16
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Ahmed BM, Hartman CK, Mezei G. Sulfate-Incarcerating Nanojars: Solution and Solid-State Studies, Sulfate Extraction from Water, and Anion Exchange with Carbonate. Inorg Chem 2016; 55:10666-10679. [PMID: 27665966 DOI: 10.1021/acs.inorgchem.6b01909] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A series of 9 homologous sulfate-incarcerating nanojars [SO4⊂{Cu(OH)(pz)}n]2- (Cun; n = 27-33; pz = pyrazolate), based on combinations of three [Cu(OH)(pz)]x rings (x = 6-14, except 11)-namely, 6 + 12 + 9 (Cu27), 6 + 12 + 10 (Cu28), 8 + 13 + 8 (Cu29), 7 + 13 + 9 (Cu29), 8 + 14 + 8 (Cu30), 7 + 14 + 9 (Cu30), 8 + 14 + 9 (Cu31), 8 + 14 + 10 (Cu32), and 9 + 14 + 10 (Cu33)-has been obtained and characterized by electrospray-ionization mass spectrometry (ESI-MS), variable-temperature 1H NMR spectroscopy, and thermogravimetry. The X-ray crystal structure of Cu29 (8 + 13 + 8) is described. Cu32 and Cu33, which are the largest nanojars in this series, are observed for the first time. Despite extensive overlap at a given temperature, monitoring the temperature-dependent variation of paramagnetically shifted pyrazole and OH proton signals in 60 different 1H NMR spectra over a temperature range of 25-150 °C and a chemical shift range from 41 ppm to -59 ppm permits the assignment of individual protons in six different sulfate nanojars in a mixture. As opposed to ESI-MS, which only provides the size of nanojars, 1H NMR offers additional information about their detailed composition. Thus, nanojars such as Cu29 (8 + 13 + 8) and Cu29 (7 + 13 + 9) can easily be differentiated in solution. High-temperature solution studies unveil a significant difference in the thermal stability of nanojars of different sizes obtained under kinetic control at ambient temperature, and aid in predicting the structure of the Cu33 nanojar, as well as in explaining the absence of the Cu11 ring from the Cu6-Cu14 series. Anion exchange studies using sulfate and carbonate reveal that, although each anion is thermodynamically preferred by a nanojar of a certain size, the exchange of an already incarcerated anion is hampered by a substantial kinetic barrier. The remarkably strong binding of anions by nanojars allows for the extraction of highly hydrophilic anions, such as sulfate and carbonate, from water into organic solvents, despite their very large hydration energies.
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Affiliation(s)
- Basil M Ahmed
- Department of Chemistry, Western Michigan University , Kalamazoo, Michigan 49008, United States
| | - Christian K Hartman
- Department of Chemistry, Western Michigan University , Kalamazoo, Michigan 49008, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University , Kalamazoo, Michigan 49008, United States
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Mezei G. Sulfate-bridged dimeric trinuclear copper(II)-pyrazolate complex with three different terminal ligands. Acta Crystallogr E Crystallogr Commun 2016; 72:1064-7. [PMID: 27536383 PMCID: PMC4971842 DOI: 10.1107/s2056989016010719] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/01/2016] [Indexed: 12/03/2022]
Abstract
The reaction of CuSO4·5H2O, 4-chloro-pyrazole (4-Cl-pzH) and tri-ethyl-amine (Et3N) in di-methyl-formamide (DMF) produced crystals of di-aqua-hexa-kis-(μ-4-chloro-pyrazolato-κ(2) N:N')bis-(N,N-di-methyl-formamide)di-μ3-hydroxido-bis-(μ4-sulfato-κ(4) O:O':O'':O'')hexa-copper(II) N,N-di-methyl-formamide tetra-solvate dihydrate, [Cu3(OH)(SO4)(C3H2ClN2)3(C3H7NO)(H2O)]2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper-pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper-pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the Cu(II) atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square-pyramidal coordination geometry around each copper cation. The metal complex and solvent mol-ecules are involved in O-H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (10-1).
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Affiliation(s)
- Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
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Ahmed BM, Mezei G. From Ordinary to Extraordinary: Insights into the Formation Mechanism and pH-Dependent Assembly/Disassembly of Nanojars. Inorg Chem 2016; 55:7717-28. [DOI: 10.1021/acs.inorgchem.6b01172] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Basil M. Ahmed
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008-5413, United States
| | - Gellert Mezei
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008-5413, United States
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Ahmed BM, Calco B, Mezei G. Tuning the structure and solubility of nanojars by peripheral ligand substitution, leading to unprecedented liquid-liquid extraction of the carbonate ion from water into aliphatic solvents. Dalton Trans 2016; 45:8327-39. [PMID: 27048621 DOI: 10.1039/c6dt00847j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nanojars, a novel class of neutral anion-incarcerating agents of the general formula [Cu(II)(OH)(pz)]n (Cun; n = 27-31, pz = pyrazolate anion), efficiently sequester various oxoanions with large hydration energies from water. In this work, we explore whether substituents on the pyrazole ligand interfere with nanojar formation, and whether appropriate substituents could be employed to tune the solubility of nanojars in solvents of interest, such as long-chain aliphatic hydrocarbons (solvent of choice for large-scale liquid-liquid extraction processes) and water. To this end, we conducted a comprehensive study using 40 different pyrazole ligands, with one, two or three substituents in their 3-, 4- and 5-positions. The corresponding nanojars are characterized by single-crystal X-ray diffraction and/or electrospray-ionization mass spectrometry (ESI-MS). The results show that Cun-nanojars with various substituents in the pyrazole 4-position, including long chains, phenyl and CF3 groups, can be obtained. Straight chains are also tolerated at the pyrazole 3-position, and favor the Cu30-nanojar. Homoleptic nanojars, however, could not be obtained with phenyl or CF3 groups. Nevertheless, if used in mixture with the parent non-substituted pyrazole, sterically hindered pyrazoles do form heteroleptic nanojars. With 3,5-disubstituted pyrazoles, only heteroleptic nanojars are accessible. The crystal structure of novel nanojars (Bu4N)2[CO3⊂{Cu30(OH)30(3,5-Me2pz)y(pz)30-y}] (y = 14 and 15) is presented. We find that in contrast to the parent nanojar, which is insoluble in aliphatic solvents and water, nanojars with alkyl substituents are soluble in saturated hydrocarbon solvents, whereas nanojars based on novel pyrazoles, functionalized with oligoether chains, are readily soluble in water. Liquid-liquid extraction of carbonate from water under basic pH is presented for the first time.
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Affiliation(s)
- Basil M Ahmed
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA.
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