Recognition of Anions, Monoamine Neurotransmitter and Trace Amine Hydrochlorides by Ureido‐Hexahomotrioxacalix[3]arene Ditopic Receptors

Teixeira, Filipa A.; Ascenso, José R.; Cragg, Peter J.; Hickey, Neal; Geremia, Silvano; Marcos, Paula M.

doi:10.1002/ejoc.201901888

Cited by 7 publications

(11 citation statements)

References 44 publications

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“…The association constants were, in average, 0.84 log units lower than those obtained for 5a , except for the best bound anions F − , AcO − and H 2 PO 4 − , whose differences were smaller (Δ log K ass = 0.13, 0.34 and 0.23, respectively). Similar results were reported before for different homooxacalixarene thiourea receptors [ 21 , 28 , 29 ], as well as thioureido-calix[4] and [6]arene analogues [ 30 , 31 ]. This fact may be related to the larger size of sulfur atom, that destabilizes the cis-cis geometry required for anion binding, causing a lower preorganization and consequently a high energy demand of the thiourea groups compared to the urea ones [ 32 ].…”

Section: Resultssupporting

confidence: 90%

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

et al. 2020

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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.

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Section: Resultssupporting

confidence: 90%

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

et al. 2020

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“…Recently, we have reported the synthesis of three hexahomotrioxacalix[3]arene- based receptors bearing (thio)urea groups linked to the macrocycle lower rim by a butyl spacer [ 32 ]. Following this line of research, we prepared three new fluorescent sensors containing (thio)urea residues and naphthalene or pyrene moieties.…”

Section: Resultsmentioning

confidence: 99%

“…Following this line of research, we prepared three new fluorescent sensors containing (thio)urea residues and naphthalene or pyrene moieties. Thus, a three-step procedure (already described) [ 32 ] was undertaken from parent compound p-tert -butylhexahomotrioxacalix[3]arene 1 . The alkylation reaction of 1 with N -(4-bromobutyl)phthalimide and K 2 CO 3 afforded triphthalimide compound 2 .…”

Section: Resultsmentioning

confidence: 99%

“…As part of our continuous interest on the host–guest properties of homooxacalixarenes (calixarene analogues in which the CH 2 bridges are partly or completely replaced by CH 2 OCH 2 groups) [ 21 , 22 ], we have reported the anion and ion pair recognition of several (thio)ureido-dihomooxacalix[4]arenes [ 23 , 24 , 25 ], including fluorescent receptors [ 26 , 27 ]. The ion affinity of hexahomotrioxacalix[3]arenes, a very interesting macrocycle formed by an 18-membered ring and having only two basic conformations, has also been investigated [ 28 , 29 , 30 , 31 , 32 , 33 ]. Recently, we have extended our research into the study of fluorescent hexahomotrioxacalix[3]arenes.…”

Section: Introductionmentioning

confidence: 99%

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Anion Binding by Fluorescent Ureido-Hexahomotrioxacalix[3]arene Receptors: An NMR, Absorption and Emission Spectroscopic Study

Miranda

Marcos

Ascenso³

et al. 2022

Molecules

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Fluorescent receptors (4a–4c) based on (thio)ureido-functionalized hexahomotrioxacalix[3]arenes were synthesised and obtained in the partial cone conformation in solution. Naphthyl or pyrenyl fluorogenic units were introduced at the lower rim of the calixarene skeleton via a butyl spacer. The binding of biologically and environmentally relevant anions was studied with NMR, UV–vis absorption, and fluorescence titrations. Fluorescence of the pyrenyl receptor 4c displays both monomer and excimer fluorescence. The thermodynamics of complexation was determined in acetonitrile and was entropy-driven. Computational studies were also performed to bring further insight into the binding process. The data showed that association constants increase with the anion basicity, and AcO−, BzO− and F− were the best bound anions for all receptors. Pyrenylurea 4c is a slightly better receptor than naphthylurea 4a, and both are more efficient than naphthyl thiourea 4b. In addition, ureas 4a and 4c were also tested as ditopic receptors in the recognition of alkylammonium salts.

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“…In a very recent contribution, Marcos and co-workers reported their latest results with cation and anion ditopic receptors based upon trisubstituted derivatives of 31 with lower-rim O-tert-butylurea, phenylthiourea or phenylurea functionalities, which are connected to the hexahomotrioxacalix [3]arene scaffold via butyl spacers. [59] Both cone and partial-cone conformers were obtained with the phenylurea but only partial-cone products, as determined by solution NMR studies and their binding properties towards several relevant anions with different geometries were assessed by proton NMR titrations. The cone conformation of the trisphenylurea derivative was also confirmed by single-crystal X-ray crystallography and also proved to be the best an anion receptor, with the highest affinity being shown toward the trigonal planar acetate and benzoate anions (log K assoc = 4.12 and 4.00, respectively) amongst the spherical, linear and tetrahedral anions tested.…”

Section: Homooxacalixarene-analogue Mcps Containing Three Aromatic Rings: "Oxacalix[3]arene" Analoguesmentioning

confidence: 99%

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

et al. 2020

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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.

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Recognition of Anions, Monoamine Neurotransmitter and Trace Amine Hydrochlorides by Ureido‐Hexahomotrioxacalix[3]arene Ditopic Receptors

Cited by 7 publications

References 44 publications

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

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

Anion Binding by Fluorescent Ureido-Hexahomotrioxacalix[3]arene Receptors: An NMR, Absorption and Emission Spectroscopic Study

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

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