Polyamine Receptors Containing Dipyridine or Phenanthroline Units: Clues for the Design of Fluorescent Chemosensors for Metal Ions

Bazzicalupi, Carla; Bencini, Andrea; Biagini, Silvia; Bianchi, Antonio; Faggi, Enrico; Giorgi, Claudia; Marchetta, Melania; Totti, Federico; Valtancoli, Barbara

doi:10.1002/chem.200900283

Cited by 27 publications

(20 citation statements)

References 117 publications

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“…[17] [f] T = (298.2 Ϯ 0.1) K; I = (0.10 Ϯ 0.01) mol dm -3 in aqueous NMe 4 Cl. [19] Although a few macrocyclic compounds with affinity for cadmium and lead that show selectivity for these metal ions in relation to zinc in aqueous solution have been reported, [3,[20][21][22][23] the series of compounds with identical donor atoms and the same pendant arms described here is the only case where it was possible to demonstrate the change of selectivity from zinc(II) to lead(II) by the gradual increase in cavity size.…”

Section: Metal Complexation Studiesmentioning

confidence: 83%

“…The pH was adjusted to 7.5 for the nickel(II) complex solution and to 7.0 for that of cadmium(II) with NMe 4 OH. The solution was evaporated to dryness, dissolved in MeOH (0.300 cm 3 ) and allowed to crystallize by slow evaporation. Single colourless crystals suitable for X-ray crystallographic determination were obtained within three days.…”

Section: Methodsmentioning

confidence: 99%

“…In this regard, macrocyclic ligands have been extensively studied. [2][3][4][5][6] Indeed, the macrocyclic framework can be adjusted by changing the number, nature and location of donor atoms, the cavity size and conformational flexibility, allowing the design of highly preorganized ligands with the ability to recognize and selectively bind certain metal ions. In particular, aza crown [ for cadmium.…”

Section: Introductionmentioning

confidence: 99%

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Properties of Metal Complexes of a New Dioxadiaza Macrocycle Containing a Dibenzofuran Unit and Acetate Pendant Arms

Mateus

Esteves

et al. 2011

Eur J Inorg Chem

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Section: Metal Complexation Studiesmentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Properties of Metal Complexes of a New Dioxadiaza Macrocycle Containing a Dibenzofuran Unit and Acetate Pendant Arms

Mateus

Esteves

et al. 2011

Eur J Inorg Chem

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“…In fact, metal binding to bpy leads to the disappearance of its absorption band at 290 nm and to the simultaneous appearance in the spectrum of a new structured band centered at ca 310 nm . Analogously, metal coordination by phen generally gives rise to a red‐shift of its absorption band at 270 nm, which is normally coupled with slight changes in molar absorbance …”

Section: Resultsmentioning

confidence: 99%

Switching on the Fluorescence Emission of Polypyridine Ligands by Simultaneous Zinc(II) Binding and Protonation

et al. 2020

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The synthesis and characterization of the two new open-chain ligands 1,15-bis-[6-(2,2'-bipyridyl)]-2,5,8,11,14-pentaaza-octadecane (L1) and 1,15-bis-[2-(1,10-phenanthroline)-9-methyl]-2,5,8,11,14-pentaazaoctadecane (L2), both featuring a tetraethylenpentaamine chain linking via methylene bridges the 6 and 2 positions of two identical 2,2'-bipyridyl (bpy) and 9-methyl-1,10phenanthroline (9-methyl-phen) moieties respectively, are reported. Their protonation and binding ability for Cu 2 + , Zn 2 + , Cd 2 + and Pb 2 + have been studied by coupling potentiometric titrations with UV-vis absorption and fluorescence emission measurements in water. L1 and L2 afford stable mono-and dinuclear complexes, in which the metal ion is bound by a single bpy or 9-methyl-phen unit and the amine groups on the aliphatic chain. However, L1 displays a greater binding ability for Cu 2 + and Zn 2 + with respect to L2, the stability constants of the [ML1] 2 + complexes being 21.8 (Cu 2 + ) and 19.4 (Zn 2 + ) log units vs 20.34 and 16.8 log. units for the corresponding L2 species. Among all the metal ions tested, only the Zn 2 + complex with L2 features an enhanced fluorescence emission at neutral pH, thanks to the simultaneous binding of one Zn 2 + ion and H + ion(s), that inhibits any possible photoinduced electron transfer (PET) process from the amine donors to the excited phen moiety. Binding of a second metal switches off the emission again.[a] Dr.by the structural characteristics of the ligand and its Zn 2 + complexes, including the number and disposition of amine donors, the overall rigidity of the molecular backbone, and, in the case of macrocyclic ligands, the dimension of the cavity. In these complexes, the heteroaromatic nitrogens are unequivocally coordinated to the metal cations. However, the stiffening of the macrocyclic structure imposed by the heteroaromatic moieties may not allow the simultaneous coordination to the metal cations of all the nitrogen donors of the binding unit. Interestingly enough, the 'benzylic' amine groups, close to the heteroaromatic unit, are not coordinated, or weakly coordinated, to the metal cation. Therefore, their lone pairs are able to quench the fluorophore excited state thanks to a photoinduced electron transfer (PET) process. As a consequence, normally fluorescent Zn 2 + complexes result to be scarcely emissive. [8a,b,22-24] In this paper, we extend this study to two open-chain ligands, L1 and L2 in Scheme 1, containing a pentaamine aliphatic chain linked at its extremities to two equal 2,2'bipyridyl (bpy) or 9-methyl-1,10-phenanthroline (9-methylphen) moieties, respectively. Our purpose is the analysis of the effects on both metal binding and sensing of the presence of two fluorogenic units linked by a flexible chain.Therefore, complex stability and fluorescence emission in the presence of metal cations will be compared to those of the previously reported ligands L3 [24] and L4 [8a] (Scheme 1), which contain the same aliphatic pentaamine chain linking the 6,6' and 2,9 positions of a single...

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“…[47–49] Due to the multitude of factors impacting the binding energies between polyamine chelators and transition metals, it is often difficult to predict optimal metal-chelator pairings. [50] Most pertinent to the study presented herein, it is known that varying the spacing between amine groups from ethylene to propylene units can significantly impact metal binding due to changes in chelator flexibility, metallocycle ring size of the bound complex, and differences in nitrogen basicity.…”

Section: Resultsmentioning

confidence: 99%

Spermine detection via metal-mediated ethynylarene ‘turn-on’ fluorescence signaling

Fletcher

Bruck

2015

Sensors and Actuators B: Chemical

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A dicarboxylated ethynylarene was shown to behave as a fluorescent chemosensor for millimolar concentrations of polyamines when mixed with Cd(II), Pb(II) or Zn(II) ions at micromolar concentrations. A bathochromic shift and intensification of fluorescence emission was observed with increasing amounts of metal ion in the presence of aqueous polyamines buffered at pH = 7.6. Such perturbations manifested as ‘turn-on’ signals from a ratiometric comparison of emission intensities at 390 nm versus 340 nm. Using Pb(II) as the metal mediator, spermine was selectively detected as a 40-fold signal enhancement relative to spermidine, putrescine, cadaverine and several other non-biogenic diamines. Evaluation of additional triamine and tetraamine analytes showed the influence that amine group quantity and spacing had on signal generation. By increasing the ratio of Pb(II) relative to ethynylarene, the detection limit for spermine was successfully lowered to a 25 micromolar level. Noncovalent association between ethynylarene, metal ion and polyamine are believed to promote the observed spectroscopic changes. This study exploits the subtle impact that polyamine structural identity has on transition metal chelation to define a new approach towards polyamine chemosensor development.

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Polyamine Receptors Containing Dipyridine or Phenanthroline Units: Clues for the Design of Fluorescent Chemosensors for Metal Ions

Cited by 27 publications

References 117 publications

Properties of Metal Complexes of a New Dioxadiaza Macrocycle Containing a Dibenzofuran Unit and Acetate Pendant Arms

Properties of Metal Complexes of a New Dioxadiaza Macrocycle Containing a Dibenzofuran Unit and Acetate Pendant Arms

Switching on the Fluorescence Emission of Polypyridine Ligands by Simultaneous Zinc(II) Binding and Protonation

Spermine detection via metal-mediated ethynylarene ‘turn-on’ fluorescence signaling

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