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Lewis Acidic Zinc(II) Complexes of Tetradentate Ligands as Building Blocks for Responsive Assembled Supramolecular Structures. CHEMISTRY 2023. [DOI: 10.3390/chemistry5010010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This review presents representative examples illustrating how the Lewis acidic character of the Zn(II) metal center in Zn(salen)-type complexes, as well as in complexes of other tetradentate ligands, and the nature of the medium govern their supramolecular aggregation, leading to the formation of a variety of supramolecular structures, either in solution or in the solid state. Stabilization of these Lewis acidic complexes is almost always reached through an axial coordination of a Lewis base, leading to a penta-coordinated square-pyramidal geometry around the metal center. The coverage is not exhaustive, mainly focused on their crystallographic structures, but also on their aggregation and sensing properties in solution, and on their self-assembled and responsive nanostructures, summarizing their salient aspects. The axial ligands can easily be displaced, either in solution or in the solid state, with suitable Lewis bases, thus being responsive supramolecular structures useful for sensing. This contribution represents the first attempt to relate some common features of the chemistry of different families of Zn(II) complexes of tetradentate ligands to their intrinsic Lewis acidic character.
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Di Bella S. Lewis acidic zinc(II) salen-type Schiff-base complexes: sensing properties and responsive nanostructures. Dalton Trans 2021; 50:6050-6063. [PMID: 33876173 DOI: 10.1039/d1dt00949d] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In this frontier article some peculiar characteristics of Zn(salen)-type Schiff-base complexes are reviewed. The paper is mainly focused on the most recent and relevant achievements on responsive supramolecular nanostructures and sensing properties, both of them related to the Lewis acidic character of the ZnII centre in these molecular species, providing an interpretation of these features. The sensing properties of Zn(salen)-type complexes mainly originate from optical spectroscopic changes associated with the formation of the adducts upon addition of a Lewis base (analyte), either by deaggregation of dimeric species or displacement of the solvent coordinated to the metal centre. In both cases the direct sensing is related either to the Lewis acidic character of the complex as well as to the Lewis basicity of the analyte. The formation of responsive nanostructures with fluorescent, and/or vapochromic, mechanochromic, and thermochromic characteristics is driven by non-mutual intermolecular ZnO interactions, further stabilized by π-π stacking interactions and/or interdigitation of the alkyl side groups. The Lewis acidic character is not a prerogative of Zn(salen)-type complexes of tetradentate Schiff-bases. Many other classes of ZnII complexes can possess this property. A correct interpretation of their chemistry is certainly useful for further development of these classical coordination compounds as new molecular materials.
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Affiliation(s)
- Santo Di Bella
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
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Consiglio G, Oliveri IP, Cacciola S, Maccarrone G, Failla S, Di Bella S. Dinuclear zinc(ii) salen-type Schiff-base complexes as molecular tweezers. Dalton Trans 2020; 49:5121-5133. [PMID: 32219249 DOI: 10.1039/d0dt00494d] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In this contribution, the synthesis and the unusual aggregation/deaggregation properties in solution of two dinuclear ZnII Schiff-base complexes of tetradentate Schiff-base units, having non-conjugated spacers between each molecular unit, are reported in comparison to the mononuclear model complex. Through detailed 1H NMR, DOSY NMR, optical absorption, fluorescence emission, and multivariate analysis of optical absorption data, emerge some interesting findings. In solution of non-coordinating solvents, these Lewis acidic species are characterized as monomers stabilized by formation of intramolecular aggregates, having distinct spectroscopic properties in comparison to intermolecular aggregates derived from the mononuclear model analogue. Instead, in coordinating solvents they exhibit a typical behaviour, with formation of stable adducts showing a strong fluorescence. Deaggregation studies using pyridine as reference Lewis base allowed establishing a larger thermodynamic stability of these intramolecular aggregates, in comparison to intermolecular aggregates, even larger than that of aggregates of conjugated multinuclear complexes. The combined analysis of spectroscopic data upon deaggregation with ditopic Lewis bases unambiguously demonstrated the formation of stable 1 : 1 adducts, with higher binding constants in comparison to those related to monotopic species. Therefore, the present Lewis acidic, dinuclear complexes behave as molecular tweezers of ditopic guests having a strong Lewis basicity.
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Affiliation(s)
- Giuseppe Consiglio
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Ivan Pietro Oliveri
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Salvatore Cacciola
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Giuseppe Maccarrone
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Salvatore Failla
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Santo Di Bella
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
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Consiglio G, Oliveri IP, Failla S, Di Bella S. On the Aggregation and Sensing Properties of Zinc(II) Schiff-Base Complexes of Salen-Type Ligands. Molecules 2019; 24:E2514. [PMID: 31324053 PMCID: PMC6651702 DOI: 10.3390/molecules24132514] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 12/18/2022] Open
Abstract
The zinc(II) ion forms stable complexes with a wide variety of ligands, but those related to Schiff-bases are among the most largely investigated. This review deals with the peculiar aggregation characteristics of Zn(II) Schiff-base complexes from tetradentate N2O2 salen-type ligands, L, derivatives from salicylaldehydes and 1,2-diamines, and is mostly focused on their spectroscopic properties in solution. Thanks to their Lewis acidic character, ZnL complexes show interesting structural, nanostructural, and aggregation/deaggregation properties in relation to the absence/presence of a Lewis base. Deaggregation of these complexes is accompanied by relevant changes of their spectroscopic properties that can appropriately be exploited for sensing Lewis bases. Thus, ZnL complexes have been investigated as chromogenic and fluorogenic chemosensors of charged and neutral Lewis bases, including cell imaging, and have shown to be selective and sensitive to the Lewis basicity of the involved species. From these studies emerges that these popular, Lewis acidic bis(salicylaldiminato)Zn(II) Schiff-base complexes represent classical coordination compounds for modern applications.
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Affiliation(s)
- Giuseppe Consiglio
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy
| | - Ivan Pietro Oliveri
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy
| | - Salvatore Failla
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
| | - Santo Di Bella
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
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Zelada-Guillén GA, Cuéllar-Sánchez AB, Romero-Ávila M, Escárcega-Bobadilla MV. Synthesis of a Novel Zn-Salphen Building Block and Its Acrylic Terpolymer Counterparts as Tunable Supramolecular Recognition Systems. MOLECULES (BASEL, SWITZERLAND) 2019; 24:molecules24122245. [PMID: 31208097 PMCID: PMC6631749 DOI: 10.3390/molecules24122245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 05/25/2019] [Accepted: 05/30/2019] [Indexed: 02/06/2023]
Abstract
In this work, we present the synthesis of a novel Zn-Salphen complex containing an allyl group, which was used as building block in the further preparation of a new family of functional terpolymers. These polymers were obtained through radical co-polymerization with methyl metacrylate (MMA) and n-butyl acrylate (nBuA) in different ratios. The supramolecular recognition behavior of each polymer was evaluated via potentiometric measurements against selected anions in aqueous media. Interestingly, this proof of concept study shows that these systems were selective against only fluoride (F−) or both, fluoride and acetate (OAc−), by tailoring the relative content of Zn-Salphen monomer, thus making them a promising starting point for modular design of chemical sensors through straightforward synthetic approaches.
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Affiliation(s)
- Gustavo A Zelada-Guillén
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, Mexico City 04510, Mexico.
| | - Ana B Cuéllar-Sánchez
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, Mexico City 04510, Mexico.
| | - Margarita Romero-Ávila
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, Mexico City 04510, Mexico.
| | - Martha V Escárcega-Bobadilla
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, Mexico City 04510, Mexico.
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Supramolecular Aggregation of a New Substituted Bis(salicylaldiminato)zinc(II) Schiff-Base Complex Derived from trans-1,2-Diaminocyclohexane. INORGANICS 2018. [DOI: 10.3390/inorganics6010008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In this contribution is reported the synthesis, characterization, and aggregation properties in solution of a novel Zn(II) complex, (R)-2, derived from the enantiopure chiral trans-1,2-diaminocyclohexane and a substituted salicylaldehyde. Detailed 1H NMR, DOSY NMR, optical absorption, and circular dichroism spectroscopic studies and chemical evidence allowed to investigate the nature of aggregate species in solution. The high solubility of (R)-2 in solution of the non-coordinating chloroform solvent leads to formation of various aggregates, some of them consisting of large oligomers estimated to contain up to 27 monomeric units. The chiral trans-stereochemistry of the bridging diamine favors a different aggregation mode in these complexes, both in the oligomers and dimers, involving a tetrahedral coordination geometry around the metal center. Overall data suggest the formation of helical oligomers, (ZnL)n, in freshly prepared chloroform solutions which, by standing or heating, evolve towards a more thermodynamically stable, dinuclear double-helicate Zn2L2 dimer.
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Oliveri IP, Forte G, Consiglio G, Failla S, Di Bella S. Aggregates of Defined Stereochemical Scaffolds: A Study in Solution of a Zinc(II) Schiff Base Complex Derived from the Enantiopure trans-1,2-Cyclopentanediamine. Inorg Chem 2017; 56:14206-14213. [DOI: 10.1021/acs.inorgchem.7b02341] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ivan Pietro Oliveri
- Dipartimento di Scienze Chimiche and ‡Dipartimento di Scienze del Farmaco, Università di Catania, I-95125 Catania, Italy
| | - Giuseppe Forte
- Dipartimento di Scienze Chimiche and ‡Dipartimento di Scienze del Farmaco, Università di Catania, I-95125 Catania, Italy
| | - Giuseppe Consiglio
- Dipartimento di Scienze Chimiche and ‡Dipartimento di Scienze del Farmaco, Università di Catania, I-95125 Catania, Italy
| | - Salvatore Failla
- Dipartimento di Scienze Chimiche and ‡Dipartimento di Scienze del Farmaco, Università di Catania, I-95125 Catania, Italy
| | - Santo Di Bella
- Dipartimento di Scienze Chimiche and ‡Dipartimento di Scienze del Farmaco, Università di Catania, I-95125 Catania, Italy
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Giestas L, Gavara R, Aguiló E, Svahn N, Lima JC, Rodríguez L. Modulation of supramolecular gold(I) aggregates by anion’s interaction. Supramol Chem 2017. [DOI: 10.1080/10610278.2017.1355462] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Letícia Giestas
- LAQV-REQUIMTE, Dep. Química Fac. Ciências e Tecnologia, Univ. Nova de Lisboa, Monte de Caparica, Portugal
| | - Raquel Gavara
- Departament de Química Inorgànica i Orgànica-Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès, Spain
| | - Elisabet Aguiló
- Departament de Química Inorgànica i Orgànica-Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès, Spain
| | - Noora Svahn
- Departament de Química Inorgànica i Orgànica-Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès, Spain
| | - João Carlos Lima
- LAQV-REQUIMTE, Dep. Química Fac. Ciências e Tecnologia, Univ. Nova de Lisboa, Monte de Caparica, Portugal
| | - Laura Rodríguez
- Departament de Química Inorgànica i Orgànica-Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès, Spain
- Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, Barcelona, Spain
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Oliveri IP, Di Bella S. Lewis basicity of relevant monoanions in a non-protogenic organic solvent using a zinc(ii) Schiff-base complex as a reference Lewis acid. Dalton Trans 2017; 46:11608-11614. [PMID: 28825067 DOI: 10.1039/c7dt02821k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The Lewis basicity of relevant anions is reported for the first time and compared with that of neutral bases.
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Affiliation(s)
| | - Santo Di Bella
- Dipartimento di Scienze Chimiche
- Università di Catania
- I-95125 Catania
- Italy
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Sabaté F, Gavara R, Giannicchi I, Bosque R, Cort AD, Rodríguez L. Ternary assemblies comprising metal–salophen complexes and 4,4′-bipyridine. NEW J CHEM 2016. [DOI: 10.1039/c5nj03210e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of ternary species containing zinc or uranyl–salophen complexes has been explored and analyzed in this work.
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Affiliation(s)
- Ferran Sabaté
- Departament de Química Inorgànica
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | - Raquel Gavara
- Departament de Química Inorgànica
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | - Ilaria Giannicchi
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione
- Università La Sapienza
- 00185 Roma
- Italy
| | - Ramon Bosque
- Departament de Química Inorgànica
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | - Antonella Dalla Cort
- Dipartimento di Chimica and IMC-CNR Sezione Meccanismi di Reazione
- Università La Sapienza
- 00185 Roma
- Italy
| | - Laura Rodríguez
- Departament de Química Inorgànica
- Universitat de Barcelona
- 08028 Barcelona
- Spain
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