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Bevilacqua M, Roverso M, Bogialli S, Graiff C, Biffis A. From Au 11 to Au 13: Tailored Synthesis of Superatomic Di-NHC/PPh 3-Stabilized Molecular Gold Nanoclusters. Inorg Chem 2023; 62:1383-1393. [PMID: 36638827 PMCID: PMC9890486 DOI: 10.1021/acs.inorgchem.2c03331] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Herein, we report a new method to synthesize molecular gold nanoclusters (AuNCs) stabilized by phosphine (PR3) and di-N-heterocyclic carbene (di-NHC) ligands. The interaction of di-NHC gold(I) complexes, with the general formula [(di-NHC)Au2Cl2] with well-known [Au11(PPh3)8Cl2]Cl clusters provides three new classes of AuNCs through a controllable reaction sequence. The synthesis involves an initial ligand metathesis reaction to produce [Au11(di-NHC)(PPh3)6Cl2]+ (type 1 clusters), followed by a thermally induced rearrangement/metal complex addition with the formation of Au13 clusters [Au13(di-NHC)2(PPh3)4Cl4]+ (type 2 clusters). Finally, an additional metathesis process yields [Au13(di-NHC)3(PPh3)3Cl3]2+ (type 3 clusters). The electronic and steric properties of the employed di-NHC ligand affect the product distribution, leading to the isolation and full characterization of different clusters as the main product. A type 3 cluster has been also structurally characterized and was preliminarily found to be strongly emissive in solution.
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Affiliation(s)
- Matteo Bevilacqua
- Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via F. Marzolo 1, 35131Padova, Italy,Consorzio
per le Reattività Chimiche e la Catalisi (CIRCC), c/o Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via
F. Marzolo 1, 35131Padova, Italy
| | - Marco Roverso
- Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via F. Marzolo 1, 35131Padova, Italy
| | - Sara Bogialli
- Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via F. Marzolo 1, 35131Padova, Italy
| | - Claudia Graiff
- Dipartimento
di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università degli Studi di Parma, Parco Area delle Scienze 17/A, 43124Parma, Italy
| | - Andrea Biffis
- Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via F. Marzolo 1, 35131Padova, Italy,Consorzio
per le Reattività Chimiche e la Catalisi (CIRCC), c/o Dipartimento
di Scienze Chimiche, Università degli
Studi di Padova, Via
F. Marzolo 1, 35131Padova, Italy,
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Poly(imidazolium) Carbosilane Dendrimers: Synthesis, Catalytic Activity in Redox Esterification of α,β-Unsaturated Aldehydes and Recycling via Organic Solvent Nanofiltration. Catalysts 2021. [DOI: 10.3390/catal11111317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Three series of poly(ionic) carbosilane dendrimers peripherally functionalized with imidazolium groups substituted on N-3 with methyl, isopropyl and 2,6-diisopropylphenyl (Dipp) were prepared up to the 3rd generation together with model monovalent imidazolium iodides and used as N-heterocyclic carbene (NHC) precursors. Catalytic activity of model and dendritic NHCs generated in situ by deprotonation with DBU was tested in redox esterification of α,β-unsaturated aldehydes and the influence of substitution, dendrimer generation, temperature and substrate structure on the reaction outcome was evaluated. Dipp substituted NHCs showed high activity and selectivity in the reaction with primary alcohols. Effectiveness of organic solvent nanofiltration for the recycling of dendritic NHCs was demonstrated on the 1st generation Dipp substituted catalyst in model redox esterification of cinnamaldehyde with benzyl alcohol. A marked increase in both activity and selectivity in the first four reaction runs was observed and this improved performance was preserved in the following catalytic cycles.
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Melancon KM, Cundari TR. Computational investigations of NHC-backbone configurations for applications in organocatalytic umpolung reactions. Org Biomol Chem 2020; 18:7437-7447. [PMID: 32940280 DOI: 10.1039/d0ob01267j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Density functional theory (DFT) and multiconfigurational self-consistent field theory (MCSCF) methods are employed to investigate variation of the electronic properties of various N-heterocyclic carbenes. Alterations to the backbone by increased or decreased conjugation, heteroatom substitution in the NHC ring, and electron-donating or -withdrawing backbone substituents are modeled. The MCSCF calculations show extensive delocalization of both the highest occupied and lowest unoccupied molecular orbitals for NHCs with polymerizable backbone substituents. The free energies of the intermediates and transition structures for benzoin condensation are also shown to be sensitive to substitution of the NHC backbone. Taken together, these results imply great sensitivity of the reactivity of poly(NHC) catalysts to backbone modification at this moiety. Implications with respect to enhancement of poly(NHC)s employed in umpolung catalysis are discussed.
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Affiliation(s)
- Kortney M Melancon
- University of North Texas, Department of Chemistry, Denton, Texas 76201, USA.
| | - Thomas R Cundari
- University of North Texas, Department of Chemistry, Denton, Texas 76201, USA.
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Smith CA, Narouz MR, Lummis PA, Singh I, Nazemi A, Li CH, Crudden CM. N-Heterocyclic Carbenes in Materials Chemistry. Chem Rev 2019; 119:4986-5056. [PMID: 30938514 DOI: 10.1021/acs.chemrev.8b00514] [Citation(s) in RCA: 353] [Impact Index Per Article: 70.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
N-Heterocyclic carbenes (NHCs) have become one of the most widely studied class of ligands in molecular chemistry and have found applications in fields as varied as catalysis, the stabilization of reactive molecular fragments, and biochemistry. More recently, NHCs have found applications in materials chemistry and have allowed for the functionalization of surfaces, polymers, nanoparticles, and discrete, well-defined clusters. In this review, we provide an in-depth look at recent advances in the use of NHCs for the development of functional materials.
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Affiliation(s)
- Christene A Smith
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Mina R Narouz
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Paul A Lummis
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Ishwar Singh
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Ali Nazemi
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Chien-Hung Li
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6
| | - Cathleen M Crudden
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada , K7L 3N6.,Institute of Transformative Bio-Molecules, ITbM-WPI , Nagoya University , Nagoya , Chikusa 464-8601 , Japan
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