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Calixarene Complexes: Synthesis, Properties and Applications

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (30 December 2020) | Viewed by 29175

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Special Issue Editors

Prof. Dr. Mario Berberan-Santos

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Guest Editor

Mario Berberan e Santos Institute for Bioengineering and Biosciences (iBB), Instituto Superior Técnico, 1049-001 Lisboa, Portugal
Interests: fluorescence and phosphorescence; molecular luminescence; optical sensing; TADF and OLEDs; fullerenes; carbon dots; supramolecular assemblies

Prof. Dr. Paula M. Marcos

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1. Centro de Química Estrutural, Institute of Molecular Sciences, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, 1749-016 Lisboa, Portugal
2. Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
Interests: macrocyclic and supramolecular chemistry; calixarenes; host-guest chemistry; ion binding; organic ion-pair recognition; NMR and UV-Vis absorption spectroscopy
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Special Issue Information

Dear Colleagues,

There is a growing interest in the development of host systems for ionic and neutral species based on calixarenes. These cyclic oligomers show important host–guest properties and therefore have numerous applications in a broad range of fields, including organocatalysis, sensing, extraction and separation, and more recently biomedical applications. The relatively simple functionality of their upper and lower rims and the presence of a pre-organized cavity that is available in different sizes and conformations make calixarenes attractive building blocks for the construction of supramolecular assemblies. This Special Issue aims to present the most recent developments on host–guest properties of calixarenes as well as new synthetic methods and applications. We welcome research articles on topics related to this field.

Prof. Mario Berberan-Santos
Prof. Paula M. Marcos
Guest Editors

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Keywords

calixarenes
new synthetic methods
host–guest properties
supramolecular assemblies
applications

Published Papers (10 papers)

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Research

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19 pages, 3479 KiB

Open AccessFeature PaperArticle

Conventional vs. Microwave- or Mechanically-Assisted Synthesis of Dihomooxacalix[4]arene Phthalimides: NMR, X-ray and Photophysical Analysis

by Alexandre S. Miranda, Paula M. Marcos, José R. Ascenso, M. Paula Robalo, Vasco D. B. Bonifácio, Mário N. Berberan-Santos, Neal Hickey and Silvano Geremia

Molecules 2021, 26(6), 1503; https://doi.org/10.3390/molecules26061503 - 10 Mar 2021

Cited by 1 | Viewed by 2040

Abstract

Direct O-alkylation of p-tert-butyldihomooxacalix[4]arene (1) with N-(bromopropyl)- or N-(bromoethyl)phthalimides and K₂CO₃ in acetonitrile was conducted under conventional heating (reflux) and using microwave irradiation and ball milling methodologies. The reactions afforded mono- and mainly distal di-substituted derivatives in the cone conformation, in a total of eight compounds. They were isolated by column chromatography, and their conformations and the substitution patterns were established by NMR spectroscopy (¹H, ¹³C, COSY and NOESY experiments). The X-ray structures of four dihomooxacalix[4]arene phthalimide derivatives (2a, 3a, 3b and 5a) are reported, as well as their photophysical properties. The microwave (MW)-assisted alkylations drastically reduced the reaction times (from days to less than 45 min) and produced higher yields of both 1,3-di-substituted phthalimides (3a and 6a) with higher selectivity. Ball milling did not reveal to be a good method for this kind of reaction. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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10 pages, 4766 KiB

Open AccessArticle

Self-Assembly of Discrete Porphyrin/Calix[4]tube Complexes Promoted by Potassium Ion Encapsulation

by Massimiliano Gaeta, Elisabetta Rodolico, Maria E. Fragalà, Andrea Pappalardo, Ilenia Pisagatti, Giuseppe Gattuso, Anna Notti, Melchiorre F. Parisi, Roberto Purrello and Alessandro D’Urso

Molecules 2021, 26(3), 704; https://doi.org/10.3390/molecules26030704 - 29 Jan 2021

Cited by 11 | Viewed by 2064

Abstract

The pivotal role played by potassium ions in the noncovalent synthesis of discrete porphyrin-calixarene nanostructures has been examined. The flattened-cone conformation adopted by the two cavities of octa-cationic calix[4]tube C4T was found to prevent the formation of complexes with well-defined stoichiometry between this novel water-soluble calixarene and the tetra-anionic phenylsulfonate porphyrin CuTPPS. Conversely, preorganization of C4T into a C_4v-symmetrical scaffold, triggered by potassium ion encapsulation (C4T@K⁺), allowed us to carry out an efficient hierarchical self-assembly process leading to 2D and 3D nanostructures. The stepwise formation of discrete CuTPPS/C4T@K⁺ noncovalent assemblies, containing up to 33 molecular elements, was conveniently monitored by UV/vis spectroscopy by following the absorbance of the porphyrin Soret band. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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15 pages, 3348 KiB

Open AccessArticle

Terpyridine-Functionalized Calixarenes: Synthesis, Characterization and Anion Sensing Applications

by Nicola Y. Edwards, David M. Schnable, Ioana R. Gearba-Dolocan and Jenna L. Strubhar

Molecules 2021, 26(1), 87; https://doi.org/10.3390/molecules26010087 - 27 Dec 2020

Cited by 10 | Viewed by 3414

Abstract

Lanthanide complexes have been developed and are reported herein. These complexes were derived from a terpyridine-functionalized calix[4]arene ligand, chelated with Tb³⁺ and Eu³⁺. Synthesis of these complexes was achieved in two steps from a calix[4]arene derivative: (1) amide coupling of a calix[4]arene bearing carboxylic acid functionalities and (2) metallation with a lanthanide triflate salt. The ligand and its complexes were characterized by NMR (¹H and ¹³C), fluorescence and UV-vis spectroscopy as well as MS. The photophysical properties of these complexes were studied; high molar absorptivity values, modest quantum yields and luminescence lifetimes on the ms timescale were obtained. Anion binding results in a change in the photophysical properties of the complexes. The anion sensing ability of the Tb(III) complex was evaluated via visual detection, UV-vis and fluorescence studies. The sensor was found to be responsive towards a variety of anions, and large binding constants were obtained for the coordination of anions to the sensor. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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8 pages, 1153 KiB

Open AccessArticle

Isolation of a Nitromethane Anion in the Calix-Shaped Inorganic Cage

by Yuji Kikukawa, Hiromasa Kitajima, Sho Kuwajima and Yoshihito Hayashi

Molecules 2020, 25(23), 5670; https://doi.org/10.3390/molecules25235670 - 01 Dec 2020

Cited by 3 | Viewed by 2159

Abstract

A calix-shaped polyoxometalate, [V₁₂O₃₂]⁴⁻ (V12), stabilizes an anion moiety in its central cavity. This molecule-sized container has the potential to control the reactivity of an anion. The highly-reactive cyanate is smoothly trapped by V12 to form [V₁₂O₃₂(CN)]⁵⁻. In the CH₃NO₂ solution, cyanate abstracts protons from CH₃NO₂, and the resultant CH₂NO₂⁻ is stabilized in V12 to form [V₁₂O₃₂(CH₂NO₂)]⁵⁻ (V12(CH₂NO₂)). A crystallographic analysis revealed the double-bond characteristic short bond distance of 1.248 Å between the carbon and nitrogen atoms in the nitromethane anion in V12. ¹H and ¹³C NMR studies showed that the nitromethane anion in V12 must not be exchanged with the nitromethane solvent. Thus, the V12 container restrains the reactivity of anionic species. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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21 pages, 6472 KiB

Open AccessArticle

Study on the Influence of Chirality in the Threading of Calix[6]arene Hosts with Dialkylammonium Axles

by Carmen Talotta, Gerardo Concilio, Paolo Della Sala, Carmine Gaeta, Christoph A. Schalley and Placido Neri

Molecules 2020, 25(22), 5323; https://doi.org/10.3390/molecules25225323 - 15 Nov 2020

Cited by 2 | Viewed by 1829

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. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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20 pages, 3856 KiB

Open AccessFeature PaperArticle

Dihomooxacalix[4]arene-Based Fluorescent Receptors for Anion and Organic Ion Pair Recognition

by Alexandre S. Miranda, Paula M. Marcos, José R. Ascenso, Mário N. Berberan-Santos, Rachel Schurhammer, Neal Hickey and Silvano Geremia

Molecules 2020, 25(20), 4708; https://doi.org/10.3390/molecules25204708 - 14 Oct 2020

Cited by 7 | Viewed by 2364

Abstract

Fluorescent dihomooxacalix[4]arene-based receptors 5a–5c, bearing two naphthyl(thio)ureido groups at the lower rim via a butyl spacer, were synthesised and obtained in the cone conformation in solution. The X-ray crystal structures of 1,3- (5a) and 3,4-dinaphthylurea (5b) derivatives are reported. Their binding properties towards several anions of different geometries were assessed by ¹H-NMR, UV-Vis absorption and fluorescence titrations. Structural and energetic insights of the naphthylurea 5a and 5b complexes were also obtained using quantum mechanical calculations. The data showed that all receptors follow the same trend, the association constants increase with the anion basicity, and the strongest complexes were obtained with F⁻, followed by the oxoanions AcO⁻ and BzO⁻. Proximal urea 5b is a better anion receptor compared to distal urea 5a, and both are more efficient than thiourea 5c. Compounds 5a and 5b were also investigated as heteroditopic receptors for biologically relevant alkylammonium salts, such as the neurotransmitter γ-aminobutyric acid (GABA·HCl) and the betaine deoxycarnitine·HCl. Chiral recognition towards the guest sec-butylamine·HCl was also tested, and a 5:2 selectivity for (R)-sec-BuNH₃⁺·Cl⁻ towards (P) or (M) enantiomers of the inherently chiral receptor 5a was shown. Based on DFT calculations, the complex [(S)-sec-BuNH₃⁺·Cl⁻/(M)-5a] was indicated as the more stable. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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17 pages, 3269 KiB

Open AccessArticle

Highly Sensitive and Selective Fluorescent Probes for Cu(II) Detection Based on Calix[4]arene-Oxacyclophane Architectures

by Alexandra I. Costa, Patrícia D. Barata, Carina B. Fialho and José V. Prata

Molecules 2020, 25(10), 2456; https://doi.org/10.3390/molecules25102456 - 25 May 2020

Cited by 10 | Viewed by 2697

Abstract

A new topological design of fluorescent probes for sensing copper ion is disclosed. The calix[4]arene-oxacyclophane (Calix-OCP) receptor, either wired-in-series in arylene-alt-ethynylene conjugated polymers or standing alone as a sole molecular probe, display a remarkable affinity and selectivity for Cu(II). The unique recognition properties of Calix-OCP system toward copper cation stem from its pre-organised cyclic array of O-ligands at the calixarene narrow rim, which is kept in a conformational rigid arrangement by a tethered oxacyclophane sub-unit. The magnitude of the binding constants (K_a = 5.30 − 8.52 × 10⁴ M⁻¹) and the free energy changes for the inclusion complexation (−ΔG = 27.0 − 28.1 kJmol⁻¹), retrieved from fluorimetric titration experiments, revealed a high sensitivity of Calix-OCP architectures for Cu(II) species. Formation of supramolecular inclusion complexes was evidenced from UV-Vis spectroscopy. The new Calix-OCP-conjugated polymers (polymers 4 and 5), synthesized in good yields by Sonogashira–Hagihara methodologies, exhibit high fluorescence quantum yields (Φ_F = 0.59 − 0.65). Density functional theory (DFT) calculations were used to support the experimental findings. The fluorescence on–off behaviour of the sensing systems is tentatively explained by a photoinduced electron transfer mechanism. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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19 pages, 2560 KiB

Open AccessArticle

Synthesis, Crystal Structure, and Biological Activity of a Multidentate Calix[4]arene Ligand Doubly Functionalized by 2-Hydroxybenzeledene-Thiosemicarbazone

by Ehsan Bahojb Noruzi, Behrouz Shaabani, Silvano Geremia, Neal Hickey, Patrizia Nitti and Hossein Samadi Kafil

Molecules 2020, 25(2), 370; https://doi.org/10.3390/molecules25020370 - 16 Jan 2020

Cited by 32 | Viewed by 3495

Abstract

The design and synthesis of a novel tert-butyl-calix[4]arene functionalized at 1, 3 positions of the lower rim with two terminal 2-hydroxybenzeledene-thiosemicarbazone moieties is reported. The new ligand with multi-dentate chelating properties was fully characterized by several techniques: ESI-Mass spectroscopy, FT-IR, 1H-NMR, and single crystal X-ray diffraction. The solid state structure confirms that the calix[4]arene macrocycle has the expected open cone conformation, with two opposite phenyl rings inclined outwards with large angles. The conformation of the two alkoxythiosemicarbazone arms produces a molecule with a C2 point group symmetry. An interesting chiral helicity is observed, with the two thiosemicarbazone groups oriented in opposite directions like a two-blade propeller. A water molecule is encapsulated in the center of the two-blade propeller through multiple H-bond coordinations. The antibacterial, antifungal, anticancer, and cytotoxic activities of the calix[4]arene-thiosemicarbazone ligand and its metal derivatives (Co2+, Ni2+, Cu2+, and Zn2+) were investigated. A considerable antibacterial activity (in particular against E. coli, MIC, and MBC = 31.25 μg/mL) was observed for the ligand and its metal derivatives. Significant antifungal activities against yeast (C. albicans) were also observed for the ligand (MIC = 31.25 μg/mL and MBC = 125 μg/mL) and for its Co²⁺ derivative (MIC = 62.5 μg/mL). All compounds show cytotoxicity against the tested cancerous cells. For the Saos-2 cell line, the promising anticancer activity of ligand L (IC₅₀ < 25 μg/mL) is higher than its metal derivatives. The microscopic analysis of DAPI-stained cells shows that the treated cells change in morphology, with deformation and fragmentation of the nuclei. The hemo-compatibility study demonstrated that this class of compounds are suitable candidates for further in vivo investigations. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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Review

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32 pages, 8503 KiB

Open AccessFeature PaperReview

Antimicrobial Activity of Calixarenes and Related Macrocycles

by Dmitriy N. Shurpik, Pavel L. Padnya, Ivan I. Stoikov and Peter J. Cragg

Molecules 2020, 25(21), 5145; https://doi.org/10.3390/molecules25215145 - 05 Nov 2020

Cited by 42 | Viewed by 3517

Abstract

Calixarenes and related macrocycles have been shown to have antimicrobial effects since the 1950s. This review highlights the antimicrobial properties of almost 200 calixarenes, resorcinarenes, and pillararenes acting as prodrugs, drug delivery agents, and inhibitors of biofilm formation. A particularly important development in recent years has been the use of macrocycles with substituents terminating in sugars as biofilm inhibitors through their interactions with lectins. Although many examples exist where calixarenes encapsulate, or incorporate, antimicrobial drugs, one of the main factors to emerge is the ability of functionalized macrocycles to engage in multivalent interactions with proteins, and thus inhibit cellular aggregation. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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19 pages, 4651 KiB

Open AccessReview

Calix[3]arene-Analogous Metacyclophanes: Synthesis, Structures and Properties with Infinite Potential

by Md. Monarul Islam, Paris E. Georghiou, Shofiur Rahman and Takehiko Yamato

Molecules 2020, 25(18), 4202; https://doi.org/10.3390/molecules25184202 - 14 Sep 2020

Cited by 6 | Viewed by 3584

Abstract

Calixarene-analogous metacyclophanes (CAMs) are a special class of cyclophanes that are cyclic polyaromatic hydrocarbons containing three or more aromatic rings linked by one or more methylene bridging groups. They can be considered to be analogues of calixarenes, since, in both types of molecules, the component aromatic rings are linked by methylene groups, which are meta to each other. Since the prototype or classical calix[4]arene consists of four benzene rings each linked by methylene bridges, which are also meta to each other, it can be considered to be an example of a functionalized [1.1.1.1]metacyclophane. A metacyclophane (MCP) that consists of three individual hydroxyl-group functionalized aromatic rings linked by methylene groups, e.g., a trihydroxy[1.1.1]MCP may therefore, by analogy, be termed in the broadest sense as a “calix[3]arene” or a “calix[3]arene-analogous metacyclophane”. Most of the CAMs reported have been synthesized by fragment coupling approaches. The design, synthesis and development of functionalized CAMs, MCPs, calixarenes and calixarene analogues has been an area of great activity in the past few decades, due their potential applications as molecular receptors, sensors and ligands for metal binding, and for theoretical studies, etc. In this review article, we focus mainly on the synthesis, structure and conformational properties of [1.1.1]CAMs, i.e., “calix[3]arenes” and their analogues, which contain three functionalized aromatic rings and which provide new scaffolds for further explorations in supramolecular and sensor chemistry. Full article

(This article belongs to the Special Issue Calixarene Complexes: Synthesis, Properties and Applications)

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