1
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Iuliano V, Talotta C, Della Sala P, De Rosa M, Soriente A, Neri P, Gaeta C. Hexahexyloxycalix[6]arene, a Conformationally Adaptive Host for the Complexation of Linear and Branched Alkylammonium Guests. Molecules 2023; 28:4749. [PMID: 37375304 DOI: 10.3390/molecules28124749] [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: 05/09/2023] [Revised: 06/05/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
Hexahexyloxycalix[6]arene 2b leads to the endo-cavity complexation of linear and branched alkylammonium guests showing a conformational adaptive behavior in CDCl3 solution. Linear n-pentylammonium guest 6a+ induces the cone conformation of 2b at the expense of the 1,2,3-alternate, which is the most abundant conformer of 2b in the absence of a guest. In a different way, branched alkylammonium guests, such as tert-butylammonium 6b+ and isopropylammonium 6c+, select the 1,2,3-alternate as the favored 2b conformation (6b+/6c+⊂2b1,2,3-alt), but other complexes in which 2b adopts different conformations, namely, 6b+/6c+⊂2bcone, 6b+/6c+⊂2bpaco, and 6b+/6c+⊂2b1,2-alt, have also been revealed. Binding constant values determined via NMR experiments indicated that the 1,2,3-alternate was the best-fitting 2b conformation for the complexation of branched alkylammonium guests, followed by cone > paco > 1,2-alt. Our NCI and NBO calculations suggest that the H-bonding interactions (+N-H···O) between the ammonium group of the guest and the oxygen atoms of calixarene 2b are the main determinants of the stability order of the four complexes. These interactions are weakened by increasing the guest steric encumbrance, thus leading to a lower binding affinity. Two stabilizing H-bonds are possible with the 1,2,3-alt- and cone-2b conformations, whereas only one H-bond is possible with the other paco- and 1,2-alt-2b stereoisomers.
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Affiliation(s)
- Veronica Iuliano
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Paolo Della Sala
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Margherita De Rosa
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Salerno, Italy
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2
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Quaratesi I, Della Sala P, Capacchione C, Talotta C, Geremia S, Hickey N, Gliubizzi R, Bruno I, Sgarlata C, Migliore R, Gaeta C, Neri P. Selective recognition of bisphenol S isomers in water by β-cyclodextrin. Supramol Chem 2021. [DOI: 10.1080/10610278.2021.1991925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Ilaria Quaratesi
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
- Bi-qemrties Spa, Zona Industriale - Buccino, Italy
| | - Paolo Della Sala
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
| | - Clotilde Capacchione
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
- Bi-qemrties Spa, Zona Industriale - Buccino, Italy
| | - Carmen Talotta
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
| | - Silvano Geremia
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche E Farmaceutiche, Università di Trieste, Trieste, Italy
| | - Neal Hickey
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche E Farmaceutiche, Università di Trieste, Trieste, Italy
| | | | | | - Carmelo Sgarlata
- Dipartimento di Scienze Chimiche, Università Degli Studi Di Catania, Catania, Italy
| | - Rossella Migliore
- Istituto di Chimica Biomolecolare, Consiglio Nazionale Delle Ricerche, Catania, Italy
| | - Carmine Gaeta
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
| | - Placido Neri
- Dipartimento di Chimica E Biologia “A. Zambelli”, Università di Salerno, Fisciano , Italy
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3
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Abstract
Hexamethoxycalix[6]arene 3 forms a directional pseudorotaxane complex with the chiral axle (S)-(α-methyl-benzyl)benzylammonium 2+. Between the two (endo-chiral)-2+@3 and (exo-chiral)-2+@3 pseudorotaxane stereoisomers, the former is preferentially formed. This result confirms the validity of the “endo-α-methyl-benzyl rule”, previously reported by us. DFT calculations suggest that C-H … π interactions between the methyl group of 2+ and the calixarene aromatic rings, determine the stereoselectivity of the threading process toward the “endo-α-methyl-benzyl preference”. An amplification of optical rotation is observed upon formation of the pseudorotaxane complex (endo-chiral)-2+@3 with respect to free axle 2+. Thus, the specifical rotation of the 1:1 mixture of chiral 2+·B(ArF)4− salt and achiral 3 was augmented upon formation of the pseudorotaxane and DFT calculations were used to rationalize this result.
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4
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Della Sala P, Del Regno R, Di Marino L, Calabrese C, Palo C, Talotta C, Geremia S, Hickey N, Capobianco A, Neri P, Gaeta C. An intramolecularly self-templated synthesis of macrocycles: self-filling effects on the formation of prismarenes. Chem Sci 2021; 12:9952-9961. [PMID: 34349965 PMCID: PMC8317625 DOI: 10.1039/d1sc02199k] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/02/2021] [Indexed: 12/18/2022] Open
Abstract
Ethyl- and propyl-prism[6]arenes are obtained in high yields and in short reaction times, independent of the nature and size of the solvent, in the cyclization of 2,6-dialkoxynaphthalene with paraformaldehyde. PrS[6]Et or PrS[6]nPr adopt, both in solution and in the solid state, a folded cuboid-shaped conformation, in which four inward oriented alkyl chains fill the cavity of the macrocycle. On these bases, we proposed that the cyclization of PrS[6]Et or PrS[6]nPr occurs through an intramolecular thermodynamic self-templating effect. In other words, the self-filling of the internal cavity of PrS[6]Et or PrS[6]nPr stabilizes their cuboid structure, driving the equilibrium toward their formation. Molecular recognition studies, both in solution and in the solid state, show that the introduction of guests into the macrocycle cavity forces the cuboid scaffold to open, through an induced-fit mechanism. An analogous conformational change from a closed to an open state occurs during the endo-cavity complexation process of the pentamer, PrS[5]. These results represent a rare example of a thermodynamically controlled cyclization process driven through an intramolecular self-template effect, which could be exploited in the synthesis of novel macrocycles.
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Affiliation(s)
- Paolo Della Sala
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Rocco Del Regno
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Luca Di Marino
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Carmela Calabrese
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Carmine Palo
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Silvano Geremia
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche e Farmaceutiche Università di Trieste Via L. Giorgieri 1 I-34127 Trieste Italy
| | - Neal Hickey
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche e Farmaceutiche Università di Trieste Via L. Giorgieri 1 I-34127 Trieste Italy
| | - Amedeo Capobianco
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia, "A. Zambelli" Università di Salerno Via Giovanni Paolo II I-84084 Fisciano Italy
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5
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Study on the Influence of Chirality in the Threading of Calix[6]arene Hosts with Dialkylammonium Axles. Molecules 2020; 25:molecules25225323. [PMID: 33203070 PMCID: PMC7696445 DOI: 10.3390/molecules25225323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/09/2020] [Accepted: 11/12/2020] [Indexed: 01/22/2023] Open
Abstract
The influence of chirality in calixarene threading has been studied by exploiting the “superweak anion approach”. In particular, the formation of chiral pseudo[2]rotaxanes bearing a classical stereogenic center in their axle and/or wheel components has been considered. Two kind of pseudo[2]rotaxane stereoadducts, the “endo-chiral” and “exo-chiral” ones, having the stereogenic center of a cationic axle inside or outside, respectively, the calix-cavity of a chiral calixarene were preferentially formed with specifically designed chiral axles by a fine exploitation of the so-called “endo-alkyl rule” and a newly defined “endo-α-methyl-benzyl rule” (threading of a hexaalkoxycalix[6]arene with a directional (α-methyl-benzyl)benzylammonium axle occurs with an endo-α-methyl-benzyl preference). The obtained pseudorotaxanes were studied in solution by 1D and 2D NMR, and in the gas-phase by means of the enantiomer-labeled (EL) mass spectrometry method, by combining enantiopure hosts with pseudoracemates of one deuterated and one unlabeled chiral axle enantiomer. In both instances, there was not a clear enantiodiscrimination in the threading process with the studied host/guest systems. Possible rationales are given to explain the scarce reciprocal influence between the guest and host chiral centers.
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6
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Iuliano V, Ciao R, Vignola E, Talotta C, Iannece P, De Rosa M, Soriente A, Gaeta C, Neri P. Multiple threading of a triple-calix[6]arene host. Beilstein J Org Chem 2019; 15:2092-2104. [PMID: 31579081 PMCID: PMC6753684 DOI: 10.3762/bjoc.15.207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/16/2019] [Indexed: 01/05/2023] Open
Abstract
The synthesis of the triple-calix[6]arene derivative 6 in which three calix[6]arene macrocycles are linked to a central 1,3,5-trimethylbenzene moiety is reported. Derivative 6 is able to give multiple-threading processes in the presence of dialkylammonium axles. The formation of pseudo[2]rotaxane, pseudo[3]rotaxane, and pseudo[4]rotaxane by threading one, two, and three, respectively, calix-wheels of 6 has been studied by 1D and 2D NMR, DOSY, and ESI-FT-ICR MS/MS experiments. The use of a directional alkylbenzylammonium axle led to the stereoselective formation of endo-alkyl pseudo[n]rotaxane stereoisomers.
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Affiliation(s)
- Veronica Iuliano
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Roberta Ciao
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Emanuele Vignola
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Carmen Talotta
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Patrizia Iannece
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Margherita De Rosa
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Annunziata Soriente
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Carmine Gaeta
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Placido Neri
- Laboratory of Supramolecular Chemistry, Dipartimento di Chimica e Biologia " A. Zambelli", Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
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7
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Tranfić Bakić M, Iuliano V, Talotta C, Geremia S, Hickey N, Spinella A, De Rosa M, Soriente A, Gaeta C, Neri P. Threading of Conformationally Stable Calix[6]arene Wheels Substituted at the Methylene Bridges. J Org Chem 2019; 84:11922-11927. [PMID: 31418261 DOI: 10.1021/acs.joc.9b01779] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Calix[6]arenes disubstituted at the methylene bridges, which are stable in the cone or 1,2,3-alternate conformation, form pseudorotaxanes with dialkylammonium axles. The cone wheel-based pseudorotaxanes are 10-100 times more stable than those obtained with the native conformationally mobile calix[6]arene wheel, as a consequence of their higher degree of preorganization. The threading of conformationally stable 1,2,3-alternate calix[6]arenes is unprecedented in the literature. Therefore, very peculiar NMR features are here evidenced for this threading process involving the less symmetrical 1,2,3-alternate calix[6]arene conformation, which implies a peculiar rototranslation motion of the axle.
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Affiliation(s)
- Marina Tranfić Bakić
- Department of Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology , University of Zagreb , Pierottijeva 6 , 10000 Zagreb , Croatia
| | - Veronica Iuliano
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Carmen Talotta
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Silvano Geremia
- Centro di Eccellenza in Biocristallografia Dipartimento di Scienze Chimiche e Farmaceutiche , Università di Trieste , via L. Giorgieri 1 , I-34127 Trieste , Italy
| | - Neal Hickey
- Centro di Eccellenza in Biocristallografia Dipartimento di Scienze Chimiche e Farmaceutiche , Università di Trieste , via L. Giorgieri 1 , I-34127 Trieste , Italy
| | - Aldo Spinella
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Margherita De Rosa
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Annunziata Soriente
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Carmine Gaeta
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
| | - Placido Neri
- Laboratory of Supramolecular Chemistry, Department of Chemistry and Biology "A. Zambelli" , University of Salerno , Via Giovanni Paolo II 132 , I-84084 Fisciano , Salerno , Italy
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8
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De Simone NA, Schettini R, Talotta C, Gaeta C, Izzo I, Della Sala G, Neri P. Directing the Cation Recognition Ability of Calix[4]arenes toward Asymmetric Phase-Transfer Catalysis. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700912] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Nicola Alessandro De Simone
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Rosaria Schettini
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Irene Izzo
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Giorgio Della Sala
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia “A. Zambelli”; Università di Salerno; Via Giovanni Paolo II 132 84084 Fisciano (Salerno) Italy
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9
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Della Sala P, Talotta C, Caruso T, De Rosa M, Soriente A, Neri P, Gaeta C. Tuning Cycloparaphenylene Host Properties by Chemical Modification. J Org Chem 2017; 82:9885-9889. [DOI: 10.1021/acs.joc.7b01588] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Paolo Della Sala
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Carmen Talotta
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Tonino Caruso
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Margherita De Rosa
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Placido Neri
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e
Biologia “A. Zambelli”, Università di Salerno, Via Giovanni
Paolo II 132, I-84084 Fisciano (Salerno), Italy
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10
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La Manna P, Talotta C, Gaeta C, Soriente A, De Rosa M, Neri P. Threading of an Inherently Directional Calixarene Wheel with Oriented Ammonium Axles. J Org Chem 2017; 82:8973-8983. [PMID: 28799754 DOI: 10.1021/acs.joc.7b01388] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The threading of monostoppered alkylbenzylammonium axles 7+ and 8+ with the calix[6]-wheel 3 can occur by both routes of entering the macrocycle 3 in the cone conformation: passage through the upper rim and the through the lower rim. Thus, under thermodynamic conditions, with both the axles 7+ and 8+, the two possible orientations of calix[2]pseudorotaxane, namely, endo-benzyl and endo-alkyl, are formed by a stereoselectivity controlled by the endo-alkyl rule. Interestingly, by 1H NMR monitoring of the threading process between 8+ and 3, we revealed two calix[2]pseudorotaxane isomers in which the calix-wheel adopts 1,2,3-alternate and cone conformations, which represent the kinetic and thermodynamic species, respectively. Finally, the synthesis of ammonium-based oriented calix[2]rotaxane is here described.
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Affiliation(s)
- Pellegrino La Manna
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Margherita De Rosa
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
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11
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De Rosa M, La Manna P, Soriente A, Gaeta C, Talotta C, Hickey N, Geremia S, Neri P. A Simple Tetraminocalix[4]arene as a Highly Efficient Catalyst under "On-Water" Conditions through Hydrophobic Amplification of Weak Hydrogen Bonds. Chemistry 2017; 23:7142-7151. [PMID: 28346722 DOI: 10.1002/chem.201701247] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Indexed: 01/05/2023]
Abstract
The simple tetraminocalix[4]arene 1, which contains weak H-bond-donor NH2 groups, is reported to be a highly efficient organocatalyst for the Vinylogous Mukaiyama Aldol Reaction (VMAR) of 2-(trimethylsilyloxy)furan 5 with α-ketoesters 6 a-l under "on-water" conditions owing to the hydrophobic amplification of weak H-bond interactions. The catalytic efficiency of calixarene catalyst 1 was shown to be closely related to its recognition abilities towards the reactants 5 and 6 through a multipoint recognition model. The proposed model provided good explanations for the differences on the reaction rate acceleration and on the stereoselectivity observed with different substrates.
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Affiliation(s)
- Margherita De Rosa
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
| | - Pellegrino La Manna
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
| | - Neal Hickey
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, via L. Giorgieri 1, 34127, Trieste, Italy
| | - Silvano Geremia
- Centro di Eccellenza in Biocristallografia, Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, via L. Giorgieri 1, 34127, Trieste, Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno, Via Ponte don Melillo, 84084, Fisciano (SA), Italy
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12
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De Rosa M, Talotta C, Gaeta C, Soriente A, Neri P, Pappalardo S, Gattuso G, Notti A, Parisi MF, Pisagatti I. Calix[5]arene Through-the-Annulus Threading of Dialkylammonium Guests Weakly Paired to the TFPB Anion. J Org Chem 2017; 82:5162-5168. [PMID: 28426214 DOI: 10.1021/acs.joc.7b00406] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Through-the-annulus threading of calix[5]arene penta-O-ethers by dialkylammonium cations coupled to the loosely coordinating superweak TFPB- anion has been achieved. 1H NMR titration data show that preorganization of the calix[5]arene scaffold leads to great thermodynamic stability of the pseudorotaxane complexes as well as to a favorable threading kinetic. Thus, calix[5]arene 1c, bearing tert-butyl groups at the wide rim, was threaded by all of the cations under study (with the exception of the dibenzylammonium 2b+) more tightly than the other derivatives under investigation (Ka's up to 2.02 ± 0.2 × 105 M-1) because of its preorganized cone conformation. According to DFT calculations, van der Waals interactions between the tert-butyl groups of 1c and the alkyl chain of the cationic axle are likely responsible for the remarkable stability observed. The threading of the calix[5]arene wheels with the asymmetric pentylbenzylammonium axle 2c+ led to the toposelective formation of the endo-pentylpseudorotaxane stereoisomer in agreement with the known "endo-alkyl rule". Owing to the steric hindrance of the axle phenyl group, the threading of the guest was seen to occur in a unidirectional fashion through the calixarene narrow rim.
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Affiliation(s)
- Margherita De Rosa
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia "A. Zambelli", Università di Salerno , Via Giovanni Paolo II 132, 84084 Fisciano (Salerno), Italy
| | - Sebastiano Pappalardo
- Dipartimento di Scienze Chimiche, Università di Catania , Viale A. Doria 6, 95125 Catania, Italy
| | - Giuseppe Gattuso
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina , Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Anna Notti
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina , Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Melchiorre F Parisi
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina , Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Ilenia Pisagatti
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina , Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
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13
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Jia F, Wang HY, Li DH, Yang LP, Jiang W. Oxatub[4]arene: a molecular "transformer" capable of hosting a wide range of organic cations. Chem Commun (Camb) 2016; 52:5666-9. [PMID: 26955919 DOI: 10.1039/c6cc01052k] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The molecular "transformer", oxatub[4]arene, was found to be able to host a wide range of organic cations. The strong binding ability is believed to originate from its four interconvertible and deep-cavity conformers. The binding behavior of such adaptable receptors may provide implications for molecular recognition in nature.
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Affiliation(s)
- Fei Jia
- Department of Chemistry, South University of Science and Technology of China, No. 1088 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, P. R. China.
| | - Hao-Yi Wang
- Department of Chemistry, South University of Science and Technology of China, No. 1088 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, P. R. China.
| | - Dong-Hao Li
- Department of Chemistry, South University of Science and Technology of China, No. 1088 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, P. R. China.
| | - Liu-Pan Yang
- Department of Chemistry, South University of Science and Technology of China, No. 1088 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, P. R. China.
| | - Wei Jiang
- Department of Chemistry, South University of Science and Technology of China, No. 1088 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, P. R. China.
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14
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Gaeta C, Della Sala P, Talotta C, De Rosa M, Soriente A, Brancatelli G, Geremia S, Neri P. A tetrasulfate-resorcin[6]arene cavitand as the host for organic ammonium guests. Org Chem Front 2016. [DOI: 10.1039/c6qo00336b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A resorcin[6]arene cavitand bearing sulfate bridges is herein reported. The host is able to interact with ammonium guests through the sulfate bridges.
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Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
| | - Paolo Della Sala
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
| | - Margherita De Rosa
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
| | - Giovanna Brancatelli
- Centro di Eccellenza in Biocristallografia
- Dipartimento di Scienze Chimiche e Farmaceutiche
- Università di Trieste
- 34127 Trieste
- Italy
| | - Silvano Geremia
- Centro di Eccellenza in Biocristallografia
- Dipartimento di Scienze Chimiche e Farmaceutiche
- Università di Trieste
- 34127 Trieste
- Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università degli Studi di Salerno
- I-84084 Fisciano
- Italy
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15
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De Rosa M, La Manna P, Soriente A, Gaeta C, Talotta C, Neri P. Exploiting the hydrophobicity of calixarene macrocycles for catalysis under “on-water” conditions. RSC Adv 2016. [DOI: 10.1039/c6ra19270j] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Thioureido-calixarene derivatives provide a rate acceleration for the vinylogous Mukaiyama aldol reaction (VMAR) under on-water conditions.
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Affiliation(s)
- Margherita De Rosa
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
| | - Pellegrino La Manna
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
| | - Annunziata Soriente
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia “A. Zambelli”
- Università di Salerno
- Salerno
- Italy
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16
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Talotta C, Gaeta C, De Rosa M, Ascenso JR, Marcos PM, Neri P. Alkylammonium Guest Induced-Fit Recognition by a Flexible Dihomooxacalix[4]arene Derivative. European J Org Chem 2015. [DOI: 10.1002/ejoc.201501319] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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17
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Talotta C, De Simone NA, Gaeta C, Neri P. Calix[6]arene Threading with Weakly Interacting Tertiary Ammonium Axles: Generation of Chiral Pseudorotaxane Architectures. Org Lett 2015; 17:1006-9. [DOI: 10.1021/acs.orglett.5b00115] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carmen Talotta
- Dipartimento di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Nicola Alessandro De Simone
- Dipartimento di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Placido Neri
- Dipartimento di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
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18
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Talotta C, Gaeta C, Neri P. Endo-Complexation of Alkylammonium Ions by Calix[4]arene Cavity: Facilitating Cation−π Interactions through the Weakly Coordinating Anion Approach. J Org Chem 2014; 79:9842-6. [DOI: 10.1021/jo5016689] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Carmen Talotta
- Dipartimento
di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Carmine Gaeta
- Dipartimento
di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
| | - Placido Neri
- Dipartimento
di Chimica e
Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy
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19
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Gaeta C, Talotta C, Della Sala P, Margarucci L, Casapullo A, Neri P. Anion-induced dimerization in p-squaramidocalix[4]arene derivatives. J Org Chem 2014; 79:3704-8. [PMID: 24645825 DOI: 10.1021/jo500422u] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Spherical anions induce the dimerization of calix[4]arene derivatives 3 and 4 bearing squaramide moieties at the exo rim (p-squaramidocalixarenes). (1)H NMR titration experiments showed that unlike the distal isomer 3, proximal p-squaramidocalixarene 4 is also able to form dimeric complexes with trigonal-planar anions.
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Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia, Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
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20
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Affiliation(s)
- Roberta Ciao
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
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21
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Ciao R, Talotta C, Gaeta C, Margarucci L, Casapullo A, Neri P. An oriented handcuff rotaxane. Org Lett 2013; 15:5694-7. [PMID: 24180584 DOI: 10.1021/ol4026974] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The first example of an oriented handcuff rotaxane has been obtained by through-the-annulus threading of a double-calix[6]arene system with a bis-ammonium axle. The relative orientation of the two calix-wheels can be predefined by exploiting the "endo-alkyl rule" which controls the directionality of the threading of alkylbenzylammonium axles with calixarene macrocycles.
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Affiliation(s)
- Roberta Ciao
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy, and Dipartimento di Farmacia, Università di Salerno , Via Giovanni Paolo II 132, I-84084 Fisciano (Salerno), Italy
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22
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Gaeta C, Talotta C, Margarucci L, Casapullo A, Neri P. Through-the-annulus threading of the larger calix[8]arene macrocycle. J Org Chem 2013; 78:7627-38. [PMID: 23834296 DOI: 10.1021/jo401206j] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A complete study of the through-the-annulus threading of the larger calix[8]arene macrocycle with di-n-alkylammonium cations has been performed in the presence of the "superweak" TFPB counterion. Thus, it was found that such threading occurs only upon partial preorganization of the calix[8]arene macroring by intramolecular bridging. In particular, 1,5-bridged calix[8]arenes with a meta- or para-xylylene bridge (2 and 3) gave pseudo[2]rotaxanes in which one dialkylammonium axle (4a-4e(+)) was threaded into one of the two subcavities of the calix[8]-wheel. Conformational studies by using chemical shift surface maps and DFT calculations evidenced a 3/4-cone geometry for these subcavities. Higher pseudorotaxane K(ass) values were obtained for calix[8]-wheels 2 and 3, with respect to calix[6]-host 1a, due to the cooperative effect of their two subcavities. Dynamic NMR studies on calix[8]-pseudorotaxanes evidenced a direct correlation between K(ass) (and ΔG(ass)) values and energy barriers for calix inversion due to the effectiveness of thread templation. In accordance with DFT calculations, an endo-alkyl preference, over the endo-benzyl one, was observed by threading calix[8]-wheel 3 with the directional n-butylbenzylammonium axle 4d(+).
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Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy.
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23
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Gaeta C, Talotta C, Neri P. The calixarene p-bromodienone route: from a chemical curiosity to an useful synthetic tool. J INCL PHENOM MACRO 2013. [DOI: 10.1007/s10847-013-0343-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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24
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Talotta C, Gaeta C, Qi Z, Schalley CA, Neri P. Pseudorotaxanes with Self-Sorted Sequence and Stereochemical Orientation. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301570] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Talotta C, Gaeta C, Qi Z, Schalley CA, Neri P. Pseudorotaxanes with Self-Sorted Sequence and Stereochemical Orientation. Angew Chem Int Ed Engl 2013; 52:7437-41. [DOI: 10.1002/anie.201301570] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/02/2013] [Indexed: 11/11/2022]
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26
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Han C, Gao L, Yu G, Zhang Z, Dong S, Huang F. Synthesis of a Difunctionalized Pillar[6]arene and Its Complexation with an Ammonium Salt Coupled to a Weakly Coordinating Counteranion. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300128] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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27
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Gaeta C, Talotta C, Mirra S, Margarucci L, Casapullo A, Neri P. Catenation of calixarene annulus. Org Lett 2012; 15:116-9. [PMID: 23286391 DOI: 10.1021/ol303142c] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Through-the-annulus-catenated calixarenes have been obtained, for the first time, by exploiting the "superweak anion" approach that allows the threading of the calix cavity with functionalized dialkylammonium axles. In addition, the first example of a stereoprogrammed synthesis of a catenane orientational isomer (an oriented calix[2]catenane) has been obtained, after macrocyclization, by using a directional alkylbenzylammonium axle.
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Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Salerno), Italy.
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28
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Gaeta C, Talotta C, Farina F, Teixeira FA, Marcos PM, Ascenso JR, Neri P. Alkylammonium cation complexation into the narrow cavity of dihomooxacalix[4]arene macrocycle. J Org Chem 2012; 77:10285-93. [PMID: 23062004 DOI: 10.1021/jo3019945] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
How big should a calixarene macrocycle be for endo-cavity complexation to occur or to allow through-the-annulus threading? To answer these questions, a complete study on the complexation of primary and secondary (di)alkylammonium cations by 18-membered p-tert-butyldihomooxacalix[4]arene macroring has been performed in the presence of the "superweak" TFPB counterion. Thus, it was found that this macrocycle is currently the smallest calixarene able to host linear and branched alkylammonium guests inside its aromatic cavity. Molecular mechanics calculations revealed that this recognition event is mainly driven by a H-bonding interaction between the guest ammonium group and the host CH(2)OCH(2) bridge. The endo-cavity complexation of chiral s-BuNH(3)(+) guest results in an asymmetric complex in the NMR time scale. The chirality transfer from guest to host is likely due to a restricted guest motion inside the tight cavity. The complexation study with secondary di-n-alkylammonium·TFPB salts revealed that the 18-membered dihomooxacalix[4]arene macroring cannot give the through-the-annulus threading with them because of its small dimension. However, the macrocycle is able to complex such ions, which can only be accommodated in an hook-like conformation characterized by two unfavorable gauche interactions around the CH(2)-NH(2)(+) bonds. The strain generated by this unfavorable folding is very likely compensated by stronger H-bonds and more favorable CH/π interactions between guest and host.
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Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Salerno), Italy.
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29
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Capici C, Gattuso G, Notti A, Parisi MF, Pappalardo S, Brancatelli G, Geremia S. Selective amine recognition driven by host-guest proton transfer and salt bridge formation. J Org Chem 2012; 77:9668-75. [PMID: 23039215 DOI: 10.1021/jo301730m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The stepwise synthesis of ionizable p-tert-butylcalix[5]arenes 1a·H and 1b·H, featuring a fixed cone cavity endowed with a carboxyl moiety at the narrow rim, is described. Single-crystal X-ray analyses have shown that in the solid state 1a·H and 1b·H adopt a cone-out conformation with the carboxylic OH group pointing in, toward the bottom of the aromatic cavity, as a result of a three- or two-center hydrogen-bonding pattern between the carboxyl group and the phenolic oxygen atom(s). The affinity of amines for calix[5]arene derivatives 1a·H and 1b·H was probed by (1)H NMR spectroscopy and single-crystal X-ray diffraction studies. These carboxylcalix[5]arenes are shown to selectively recognize linear primary amines--over branched, secondary, and tertiary amines--by a two-step process involving a proton transfer from the carboxyl to the amino group to provide the corresponding alkylammonium ion, followed by binding of the latter inside the cavity of the ionized calixarene. Proton transfer occurs only with linear primary amines, that is, when the best size and shape fit between host and substrate is achieved, while the other amines remain in their noncompeting unprotonated form. The role of the solvent in the ionization/complexation process is discussed. Structural studies on the n-BuNH(2) complexes with 1a·H and 1b·H provide evidence that binding of the in situ formed n-BuNH(3)(+) substrate to the cavity of the ionized macrocycle is ultimately secured, in the case of 1a·H, by the formation of an unprecedented salt-bridge interaction.
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Affiliation(s)
- Calogero Capici
- Dipartimento di Scienze Chimiche, Università di Messina, viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
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30
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Talotta C, Gaeta C, Neri P. Stereoprogrammed Direct Synthesis of Calixarene-Based [3]Rotaxanes. Org Lett 2012; 14:3104-7. [DOI: 10.1021/ol3011997] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carmen Talotta
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Salerno), Italy
| | - Carmine Gaeta
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Salerno), Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia and NANO_MATES Research Center, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Salerno), Italy
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