Antonio Caballero

University of Murcia | UM · Department of Organic Chemistry

We describe here a comparative study between two tripodal anion receptor based on selenophene as binding motif, the receptors use benzene or perfluorobenzene as spacer. The presence of the electron-withdrawing ring activates the Selenium atom for anion recognition inducing the formation of self-assembly supramolecular structures with the presence o...

We report here the generation of a self-assembly supramolecular polymer in which the cooperative action of anti-electrostatic anion-anion and halogen-bonding interactions serve as a powerful driven force to form large...

The synthesis and halide binding studies of three new families of sulfur, selenium, and tellurium‐based anion receptors based on chalcogen bonding interactions are reported. More information can be found in the Full Paper by A. Frontera, A. Caballero, et al. on page 4706.

“These surface plots have resulted to be an important contribution to this work because they shed light into the binding site where the anion is placed upon complexation that is actually different from the binding site that both groups envisaged when the receptors were designed.” Read more about the story behind the cover in the Cover Profile and a...

The utilization of anions to induce the formation of self-assembled supramolecular polymers in solution is an undeveloped area of host–guest chemistry. We report in this manuscript a comparative study of two tripodal anion receptors by hydrogen or halogen bonding interactions to form self-assembly supramolecular structures induced by the presence o...

The utilization of neutral receptors for the molecular recognition of anions based on chalcogen bonding (ChB) is an undeveloped area of host‐guest chemistry. In this manuscript, the synthesis of two new families of sulfur, selenium, and tellurium‐based ChB binding motifs are reported. The stability of the thiophene, selenophene, and tellurophene bi...

Through a Cu-catalyzed Huisgen cycloaddition between terminal alkynes and azides (CuAAC) reaction, azide [(μ-SCH2)2N(4-N3C6H4)Fe2(CO)6] has demonstrated to be a robust and versatile reagent able to incorporate the [(μ-SR)2Fe2(CO)6] fragment on a wide range of substrates, ranging from aromatic compounds to nucleosides, metallocenes, or redox and lum...

We describe here the utilization of 1,4-Naphthoquinone and 3-iodo-1,4-Naphthoquinone motif as new anion binding sites by hydrogen-or halogen-bonding interactions respectively. These binding sites have been integrated in bidentate ester based receptors. Emission experiments reveals that both receptors recognize selectively sulfate anion, which induc...

A 2-haloimidazole-tetraphenylethylene ion-pair receptor 1 is shown to recognise only HSO4- anions in the presence of a cobound Zn2+ cation guest species, which induced a remarkable increase with concomitant blue shift of the emission band of the complex [1•2Zn]4+ whereas no affinity of the free receptor 1 by the anions is observed. In addition, the...

The preparation and sensing properties of a tetracyclic cyclophane receptor containing two imidazolium rings as anion binding sites and two fluorene rings as fluorescent signaling units, are reported. The receptor behaves as a selective fluorescent chemosensor molecule for inorganic phosphates. ¹H‐NMR spectroscopical data clearly indicate the simul...

We present the synthesis and oxoanion-assembling properties of a monomer with a naphthalene ring as a central core decorated with two arms containing iodotriazolium rings as anion binding sites. Interactions with SO42-, H2PO4- and HP2O73- anions, via cooperative mechanism afforded a new set of supramolecular materials stabilized by a combination of...

Most of the halogen bonding receptors for anions described use halogen bonding binding sites solely in the anion recognition process; only a few examples report the study of anion receptors in which the halogen bonding interaction has been used in combination with any other non-covalent interaction. With the aims to extend the knowledge in the beha...

This review highlights the most significant examples of an emerging field in the design of highly selective anion receptors. To date, there has been remarkable progress in the binding and sensing of anions. This has been driven in part by the discovery of ways to construct effective anion binding receptors using the dominant N–H functional groups a...

The synthesis and sensing properties of a triferrocene-bis-iodotriazole is described. In general, the XB receptor 3 undergoes remarkable cathodic shifts of the two redox peaks in the presence of several oxoanions, these perturbations, which are attributable to noncovalent halogen bonding interactions, are slightly smaller than those observed for th...

A series of two-armed 2,4,5-trimethylimidazolium-based oxoanion receptors, which incorporate two end-capped photoactive anthracene rings, being the central core an aromatic or heteroaromatic ring, has been designed. In the presence of HP2O73-, H2PO4- and SO42- anions, 1H- and 31P-NMR spectroscopical data clearly indicate the simultaneous occurrence...

Several bis-triazolium-based receptors have been synthesized and their anion-recognition capabilities have been studied. The central chiral 1,1'-bi-2-naphthol (BINOL) core features either two aryl or ferrocenyl end-capped side arms with central halogen- or hydrogen-bonding triazolium receptors. NMR spectroscopic data indicate the simultaneous occur...

Several bis(triazolium)-based receptors have been synthesized as chemosensors for anion recognition. The central naphthalene core features two aryltriazolium side-arms. NMR experiments revealed differences between the binding modes of the two triazolium rings: one triazolium ring acts as a hydrogen-bond donor, the other as an anion-π receptor. Rece...

Two new pyrene-polychlorotriphenylmethyl (PTM) dyads and triads have been synthesized and characterized by optical, magnetic, and electrochemical methods. The interplay between the different electronic states of the PTM moiety in the dyads and triads and the optical and magnetic properties of the molecules have been studied. The electronic spectra...

A mixed halogen- and hydrogen-bonding hetero-[2]catenane has been synthesised via an anion templated Grubbs’ II-catalysed RCM clipping mechanical bond forming methodology. 1H NMR spectroscopy and fluorescence titration experiments demonstrated the interlocked catenane host to be capable of binding and sensing anions, in particular forming strong as...

Novel bidentate bis-(benzimidazolium) receptor containing pyrene as fluorescent signaling units has been synthesized. Fluorescent and NMR spectroscopy studies reveal that this receptor exclusively recognizes sulphate and hydrogenpyrophosphate in the competitive water-DMSO (1:9) medium; significant downfield shifts were observed for the C(2)-H proto...

The first example of utilizing halogen-bonding anion recognition to facilitate molecular motion in an interlocked structure is described. A halogen-bonding and hydrogen-bonding bistable rotaxane is prepared and demonstrated to undergo shuttling of the macrocycle component from the hydrogen-bonding station to the halogen-bonding station upon iodide...

The first example of utilizing halogen-bonding anion recognition to facilitate molecular motion in an interlocked structure is described. A halogen-bonding and hydrogen-bonding bistable rotaxane is prepared and demonstrated to undergo shuttling of the macrocycle component from the hydrogen-bonding station to the halogen-bonding station upon iodide...

This review describes the concept and exploitation of a strategic anion templation methodology in the construction of a range of interlocked host molecular frameworks designed to recognize anionic guest species in competitive aqueous media. Rotaxane and catenane receptors that contain unique anion binding cavity domains are demonstrated to exhibit...

We have designed a series of triazolium-pyrene based dyads to probe their potential as fluorescent chemosensors for anion recognition through combinations of hydrogen and halogen bonding. Cooperation between the two distinct noncovalent interactions leads to an unusual effect on receptor affinity, as a result of fundamental differences in the inter...

C4-H and C5-H protons of the imidazolium heterocycle have been exploited as a binding site for anion recognition in the design of two new redox-active imidazoliophane syn and anti isomers. The cooperative action of the two imidazolium motifs of the syn isomer is crucial for halide anion recognition. The integration of a ferrocene signalling unit at...

Two new bis-haloimidazolium macrocycles are described, containing either chloro or iodoimidazolium heterocycles. Crystal structure determinations of these macrocycles as their bromide salts are reported, as well as of the nitrate salt of the analogous bis-bromoimidazolium macrocycle. In all structures, short halogen bonds are observed in the solid...

A bis(triazolium)-based receptor designed for anion recognition is presented. NMR spectroscopic data indicate that one triazolium ring is acting as a hydrogen bond donor, whereas the second triazolium ring behaves as an anion-π receptor. The simultaneous presence of two noncovalent interactions allows us to achieve a highly selective binding of the...

Getting connected: The formation of pseudorotaxane assemblies between a designed macrocyclic halogen bonding (XB) acceptor (red in scheme) and a series of XB donor threading components was templated by a single halogen bond. The strength of the XB assembly between the pyridine macrocycle and iodopyridinium thread was utilized in the ring-closing me...

The 2-iodoimidazolium group is exploited in the anion-templated assembly of pseudorotaxanes with isophthalamide containing macrocycles. Crystallographic and solution-phase studies illustrate that the iodo-imidazolium motif is a potent halogen bond donor, forming the most stable interpenetrated assemblies in solution with the chloride anion template...

The selective absorbance detection of mercury(ii) (Hg(2+)) and lead(ii) (Pb(2+)) ions using ferrocene-based colorimetric ligands and miniaturized multiple internal reflection (MIR) systems implemented in a low-cost photonic lab on a chip (PhLoC) is reported. The detection principle is based on the formation of selective stable complexes between the...

The synthesis and anion binding properties of a new family of fluorescent halogen bonding (XB) macrocyclic halo-imidazolium receptors are described. The receptors contain chloro-, bromo-, and iodo-imidazolium motifs incorporated into a cyclic structure using naphthalene spacer groups. The large size of the iodine atom substituents resulted in the i...

The anion-templated synthesis of a halogen-bonding catenane, which recognizes chloride and bromide ions solely by halogen bonding, is described. The catenane's ability to optically sense halide anions using fluorescence spectroscopy is demonstrated.

A bidentate halogen-bonding bromoimidazoliophane receptor selectively binds bromide ions in competitive aqueous media (see picture, gray=carbon, blue=nitrogen, brown=bromine). The bromide ions are bound by cooperative convergent bromine atom/halogen-bonding halide anion interactions.

A new chemosensor molecule 3 based on a ferrocene-quinoxaline dyad recognizes mercury (II) cations in acetonitrile solution. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red-shift (Δλ=140 nm) of the low-energy band, are observed in its absorption spectrum. This change in the absorption spectrum is...

The ferrocene-benzobisimidazole derivative shows high affinity for Pb(2+) and Zn(2+) metal cations over a range of other metal cations examined. In the presence of Pb(2+) the emission spectrum is red-shifted by 13 nm with an important chelation-enhanced fluorescence effect (CHEF) CHEF = 55. The presence of Zn(2+) cations also induced a perturbation...

A new structurally simple motif, where two anthracene moieties are linked by a 2-aza-1,3-butadiene bridge has been synthesized and characterized. This new molecular probe senses Yb3+ metal cations through two different channels: a colour change from yellowish to orange, which can be used for its “naked-eye” detection, and a remarkable enhancement i...

We report a set of novel receptors with the structural feature of having an naphthyl-, pyrenyl- or ferrocenyl subunits, directly linked to a 2-aza-1,3-butadiene moiety which, in general, can be used for the rapid and selective detection of Hg2+. After coordination with this metal cation, the derivatives having two different signaling units, such as...

The synthesis, electrochemical, optical, and anion sensing properties of ferrocene-fused imidazole dyads are presented. Ferrocene-benzobisimidazole dyad 1 behaves as a highly selective redox, chromogenic and fluorescent chemosensor molecule for AcO(-) anion in DMSO/H(2)O: the oxidation redox peak is cathodically shifted (DeltaE(1/2) = -170 mV), per...

The synthesis of ferrocene-based heteroditopic receptors in which the ferrocene moiety is attached to an imidazo[4,5-e]benzothiadiazole or imidazo[4,5-f]quinoxaline is reported. These nitrogen-rich ferrocene derivatives show remarkable ion-sensing properties because of the presence of the redox active ferrocene unit and the polyazaheteroaromatic ri...

A new chemosensor molecule 4 based on a ferrocene-azaquinoxaline dyad effectively recognizes Hg(2+) in an aqueous environment as well as Pb(2+) and Zn(2+) metal cations in CH(3)CN solution through three different channels. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red shift (Deltalambda = 112-4...

The ferrocene-pyrene dyad 3 is able to selectively sense the pyrophosphate anion. The anion recognition was evaluated using electrochemistry, (1)H NMR, as well as fluorescence spectroscopy. The binding event can be inferred from either the redox-shift (DeltaE(1/2) = -100 mV) or the emission intensity ratio of the pyrene monomer to the excimer emiss...

New ferrocenyl-containing imidazopyridine and imidazophenazine receptors 2-5 show high selective affinity for Pb(II) ions over a range of other metal ions examined through different channels. Imidazopyridine-ferrocene dyad 2 behaves as a highly selective redox, chromogenic, and fluorescent chemosensor molecule for Pb(2+) cations: the oxidation redo...

The synthesis, electronic and spectroelectrochemical studies of a cyclometalated heteroleptic Ir(iii) complex containing a redox active ferrocenyl imidazophenanthroline ancillary ligand, is presented. Depending on the oxidation state of the ferrocene, controlled by external electrochemical stimuli, the emission fluorescence intensity of this bistab...

The preparation, electrochemical, electronic, and cation sensing properties of an indole-ferrocene-indole triad, are presented. A salient feature of this new structural motif is that the redox-active organometallic fragment is linked to the indole rings by unsaturated nitrogen functionalities. Triad behaves as a highly selective dual-redox and chro...

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This manuscript provides a summary of the relatively large body of research on the preparation and sensing properties of ferrocenes containing nitrogen functionalities, which have been mainly developed by our research group. After a general overview of the topic, selected recent advances in this field are described. In particular, new acyclic and c...

The synthesis, electrochemical, optical, and cation-sensing properties of ferrocene-pentakis(phenylthio)benzene dyads, linked through a putative cation-binding 2-azadiene bridge, are presented. Dyad 5 behaves as a highly selective dual-redox and chromogenic chemosensor molecule for Pb(2+) cations; the oxidation redox peak is anodically shifted (Del...

A new chemosensor molecule 1 based on a ferrocene-imidazophenanthroline dyad, effectively recognizes aqueous hydrogenpyrophosphate and the organic anions ADP and ATP through three different channels. A cathodic shift of the ferrocene/ferrocenium oxidation wave (Delta E 1/2 ranging from -130 mV for hydrogenpyrophosphate and fluoride to -40 mV for AD...

A new redox, chromogenic, and fluorescent chemosensor molecule based on a deazapurine ring selectively senses aqueous Pb2+ in acetonitrile over other metal ions examined: redox shift (DeltaE1/2 = 0.15 V of the Fe(II)/Fe(III) redox couple), the colorless to orange color change, and an emission change of 620-fold, with an unprecedented detection limi...

A test paper for high-selectivity detecting Hg2+ ions in mixed acetonitrile-watersolutions has been achieved using a bis(ferrocenyl) azine, as chromogenic chemosensormolecule, and a solid cellulose fibre, as a substrate. Depending on the amount of mercuryions in contact with the detecting molecule a spectacular color change in the celluloseindicato...

The synthesis, electrochemical, and optical properties of homo- (5, 8, 9, and 12) and heterometallic (6, 7, 10, and 11) ferrocene-ruthenocene triads, are presented. Triferrocenyl derivatives 5 and 9 form the mixed-valence species 5*+ and 92+ by partial oxidation, which show intramolecular electro-transfer phenomena. Interestingly, spectroelectroche...

A new probe, based on a 1,1'-disubstituted ferrocene, senses Zn2+ selectively among heavy and transition-metal (HTM) ions through three different channels: anodic redox shift of the Fe(II)/Fe(III) redox couple, the orange to deep purple color change that is visible to the naked-eye, and a remarkable enhancement of the fluorescence.

The synthesis, electrochemical, electronic, and cation sensing properties of the ruthenocene-terminated 2-aza-1,3-butadiene 2, linear ferrocene-ruthenocene dyads 3 and 5, and the new structural motifs diaza[4.4]ruthenocenophane 7 and mixed ferrocene and ruthenocene metallocenophanes 8 and 10 are presented. The properties of these compounds have bee...

The synthesis, optical and electrochemical properties, and X-ray characterization of two thiazole derivatives capped by ferrocenyl groups (5 and 7) and their model compounds with one ferrocenyl, either at 2 or 5 position of the mono- or bis-thiazolyl rings (3, 9, 11, and 14), are presented. Bisferrocenyl thiazole 5 forms the mixed-valence species 5...

Export Date: 24 April 2012, Source: Scopus, Art. No.: 4300412

[Structure: see text] A new probe based on an anthryl derivative bearing an azadiene side chain selectively senses Cu2+ in acetonitrile through two different channels: the yellow-to-orange color change and a remarkable enhancement of the fluorescence, whereas the pyrenyl analogous behaves as a fluorescent sensor for Cu2+ and Hg2+ in aqueous environ...

The synthesis, electrochemical, electronic and cation sensing properties of ferrocene-thiophene ligands, linked by 2-aza-1,3-butadiene bridges, whose characteristics have been systematically varied by introducing the ferrocene moiety at the 1- or 4-position of the aza bridge, are presented. Spectroelectrochemical studies revealed the presence of lo...

Two new chemosensors that exhibit high affinity and high selectivity for Hg2+ in aqueous environment which operate through two different channels, optic/redox and optic/fluorescent, are reported. The optical change in sensing can be used even for a "naked-eye" detection of Hg2+ ions, whereas the fluorescent response can be modulated by varying the...

[structure: see text]. A novel linear triferrocene derivative has been prepared and proven to be of special interest in the study of intramolecular electron transfer and as a specific optical and electrosensor for Mg(2+) cation.

The synthesis and study of structural and electronic properties of mono-ferrocenyl pi-conjugated complexes 5a-d, whose electronic characteristics have been systematically varied by introducing an electron-donating or electron-withdrawing substituent either at the 1-position or at the 4-position of the 2-aza-1,3-butadiene moiety linked to the ferroc...

The synthesis and study of structural and electronic properties of mono-ferrocenyl π-conjugated complexes 5a–d, whose electronic characteristics have been systematically varied by introducing an electron-donating or electron-withdrawing substituent either at the 1-position or at the 4-position of the 2-aza-1,3-butadiene moiety linked to the ferroce...

Times Cited: 31

A new 1-(9-anthryl)-4-ferrocenyl-2-aza-1,3-butadiene showing selective fluorescence enhancement upon binding to lithium cations over other alkaline cations in aqueous environment has been conveniently synthesized and characterized. [structure: see text]

Times Cited: 0

Cited By (since 1996): 30, Export Date: 24 April 2012, Source: Scopus