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1.
Org Biomol Chem ; 18(18): 3475-3480, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32329760

RESUMO

An investigation into the self-assembly of two 4-amino- and a 4-bromo-1,8-naphthalimide (Nap) based structures (1-3) possessing an appended glycan unit, from protic polar media, is presented. The results demonstrate the formation of complex hierarchical luminescent aggregates, wherein the morphologies, sizes and spherical structures were highly dependent on both the media and the Nap structure. Upon cleaving the native glycosidic bond, using an enzyme, the structure/morphology of the self-assembly of 3 in buffered solution was significantly transformed.

2.
Chem Commun (Camb) ; 56(17): 2562-2565, 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32011616

RESUMO

The 4-amino-1,8-naphthalimide-Tröger's base fluorophore, TBNap-TPy, adorned with phenyl-terpyridine moiety was synthesised and assessed for its aggregation-induced emission (AIE) behaviour. TBNap-TPy was further employed as a fluorescent sensor for the discriminative sensing of π-electron-deficient nitroaromatic; the TBNap-TPy displaying the largest fluorescence quenching with high selectivity for picric acid, a harmful environmental pollutant widely used in the dye industries.

3.
Chem Commun (Camb) ; 55(12): 1754-1757, 2019 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-30664130

RESUMO

Two lanthanide luminescent naphthyl-dipicolinic amide (dpa) methacrylate monomers for the synthesis of grafted supramolecular co-polymer gels (hydrogels), and their use as additional crosslinks in robust covalently cross-linked HEMA hydrogels is presented; the results demonstrate the importance of the ligand symmetry for the Eu(iii) emission from the hydrogels.

4.
Dalton Trans ; 47(46): 16377-16387, 2018 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-30379167

RESUMO

Combination of different properties has always proven effective in the generation of hybrid materials with novel interesting properties. Ln(iii) containing materials possessing multiple properties are useful in a wide range of applications. In this article, key and recent examples of metallo-supramolecular polymers in the formation of gels, soft polymeric materials and films are discussed. There is a focus on the use of trivalent lanthanide, Ln(iii), ions to provide soft materials with advanced mechanical and luminescence properties for applications in developing electronic- and bio-technologies. This frontier article has been written with the intention of reaching a broad range of readers from various backgrounds such as chemistry, materials chemistry, spectroscopy and biochemistry. Additionally, we evaluate how the unique and versatile properties of such hybrid materials can be tuned and explored to enhance the efficiency, as well as research, for new ones. Finally, an assessment of the current state-of-the-art and our outlook for the future of this field is made.

5.
Dalton Trans ; 47(35): 12308-12317, 2018 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-30113616

RESUMO

Chiral lanthanide-based supramolecular structures have gained significant importance in view of their application in imaging, sensing and other functional purposes. We have designed chiral C2-symmetrical ligands (L) based on the use of two 2,6-pyridine-dicarboxylic-amide moieties (pda), that differ from one another by the nature of the diamine spacer groups (from 1,3-phenylenedimethanamine (1(S,S), 2(R,R)) and benzene-1,3-diamine (3(S,S), 4(R,R)) to much bulkier 4,4'-(cyclohexane-1,1-diyl)bis(2,6-dimethylaniline) (5(S,S), 6(R,R))) between these two pda units. The self-assembly between L and Eu(iii) ions were investigated in CH3CN solution at low concentration whereby the changes in the absorbance, fluorescence and Eu(iii)-centred emission spectra allowed us to model the binding equilibria occurring in the solution to the presence of [Eu:L2], [Eu2:L2], [Eu2:L3] assemblies and reveal their high binding constant values. The self-assembly in solution were also studied at higher concentration by following the changes in the 1H NMR spectra of the ligands upon Eu(iii) addition, as well as by using MALDI-MS of the isolated solid state complexes. The chiroptical properties of the ligands were used in order to study the structural changes upon self-assembly between the ligands and Eu(iii) ions using circular dichroism (CD) and circularly polarised luminescence (CPL) spectroscopies. The photophysical properties of [Eu2:L3] complexes were evaluated in solution and showed a decrease of luminescence quantum yield when going from the ligand with smaller (1(S,S)) to bulkier (5(S,S)) linker from ∼5.8% to ∼2.6%. While mass-spectrometry revealed the possible formation of trinucler assemblies such as [Eu3:L3] and [Eu3:L2].

6.
Chemphyschem ; 18(13): 1746-1751, 2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28570018

RESUMO

The development of material-supported molecular logic gate mimics (MGLMs) for contained application and device fabrication has become of increasing interest. Herein, we present the formation of ≈5 nm gold nanoparticles (AuNPs) that have been surface-modified (via a thiol linkage) with heptadentate cyclen-based complexes of europium and terbium for sensing applications using delayed lanthanide luminescence and as integrated logic gate mimics within competitive media.

7.
Chem Sci ; 8(5): 3419-3426, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28507713

RESUMO

White-light-emitting materials have attracted significant interest in recent years due to their potential applications in solid-state lighting and flat-panel displays. Design of such materials is challenging and often relies on the use of multiple fluorophores despite the fact that single component systems yield materials with enhanced stability and reproducibility. Herein, we have developed a white-light-emitting system based on the formation of discrete lanthanide-based self-assembled complexes using a newly-designed ligand. We demonstrate that fine tuning of the lanthanide ions molar ratio in the self-assemblies combined with the intrinsic blue fluorescence of the ligand allows for the successful emission of pure white light with CIE coordinates of (0.33, 0.34).

8.
Chemistry ; 22(28): 9709-23, 2016 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-27258206

RESUMO

Here we have investigated the influence of the antenna group position on both the formation of chiral amphiphilic Eu(III) -based self-assemblies in CH3 CN solution and, on the ability to form monolayers on the surface of quartz substrates using the Langmuir-Blodgett technique, by changing from the 1-naphthyl (2(R), 2(S)) to the 2-naphthyl (1(R), 1(S)) position. The evaluation of binding constants of the self- assemblies in CH3 CN solution was achieved using conventional techniques such as UV/Visible and luminescence spectroscopies along with more specific circular dichroism (CD) spectroscopy. The binding constants obtained for EuL, EuL2 and EuL3 species in the case of 2-naphthyl derivatives were comparable to those obtained for 1-naphthyl derivatives. The analysis of the changes in the CD spectra of 1(R) and 1(S) upon addition of Eu(III) not only allowed us to evaluate the values of the binding constants but the resulting recalculated spectra may also be used as fingerprints for assignment of the chiral self-assembly species formed in solution. The obtained monolayers were predominantly formed from EuL3 (≈85 %) with the minor species present in ≈15 % EuL2 .

9.
Inorg Chem ; 54(16): 7735-41, 2015 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-26222397

RESUMO

The tripodal terpyridine ligand, L, forms 1D helical supramolecular polymers/gels in H2O-CH3OH solution mediated through hydrogen bonding and π-π interactions. These gels further cross-link into 3D supramolecular metallogels with a range of metal ions (M) such as Fe(II), Ni(II), Cu(II), Zn(II), and Ru(III); the cross-linking resulting in the formation of colored or colorless gels. The fibrous morphology of these gels was confirmed using scanning electron microscopy (SEM); while the self-assembly processes between L and M were investigated by absorbance and emission spectroscopy from which their binding constants were determined by using a nonlinear regression analysis.


Assuntos
Metais Pesados/química , Piridinas/química , Géis , Ligantes
10.
J Am Chem Soc ; 137(5): 1983-92, 2015 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-25590898

RESUMO

Herein we present the use of lanthanide directed self-assembly formation (Ln(III) = Eu(III), Tb(III)) in the generation of luminescent supramolecular polymers, that when swelled with methanol give rise to self-healing supramolecular gels. These were analyzed by using luminescent and (1)H NMR titrations studies, allowing for the identification of the various species involved in the subsequent Ln(III)-gel formation. These highly luminescent gels could be mixed to give a variety of luminescent colors depending on their Eu(III):Tb(III) stoichiometric ratios. Imaging and rheological studies showed that these gels prepared using only Eu(III) or only Tb(III) have different morphological and rheological properties, that are also different from those determined upon forming gels by mixing of Eu(III) and Tb(III) gels. Hence, our results demonstrate for the first time the crucial role the lanthanide ions play in the supramolecular polymerization process, which is in principle a host-guest interaction, and consequently in the self-healing properties of the corresponding gels, which are dictated by the same host-guest interactions.


Assuntos
Európio/química , Substâncias Luminescentes/química , Compostos Organometálicos/química , Reologia , Térbio/química , Géis
11.
Chem Sci ; 6(1): 457-471, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-28936303

RESUMO

The binding of asymmetrical and optically pure tridentate ligands (L = 1(S) and 1(R)) containing one carboxylic group and 2-naphthyl as an antenna to lanthanide ions (M = La(iii) and Eu(iii)) was studied in CH3CN, showing the successive formation of M:L, M:L2 and M:L3 stoichiometric species in solution. The europium complexes EuL3 were also synthesised, structurally characterised and their photophysical properties probed in CH3OH and CH3CN. The changes in the chiroptical properties of both 1(S) and 1(R) were used (by circular dichroism (CD) spectroscopy) to monitor the formation of these chiral self-assemblies in solution. While circularly polarised luminescence (CPL) showed the formation of Eu(1(S))3 and Eu(1(R))3 as enantiomers, with high luminescence dissymmetry factors (glum), fitting the CD changes allowed for binding constants to be determined that were comparable to those seen in the analyses of absorbance and luminescence changes.

12.
Dalton Trans ; 43(1): 196-209, 2014 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-24149846

RESUMO

2,6-Bis(1,2,3-triazol-4-yl)pyridine (btp) is a terdentate binding motif that is synthesised modularly via the CuAAC reaction. Herein, we present the synthesis of ligands 1 and 2 and the investigation of the coordination chemistry, photophysical behaviour and electrochemistry of complexes of these with a number of d-metal ions (e.g. Ru(II), Ir(III), Ni(II) and Pt(II)). The X-ray crystal structures of ligand 1 and the complexes [Ru·2(2)](PF6)Cl, [Ni·1(2)](PF6)Cl and [Ir·1Cl3] are also presented. All of the complexes displayed non-classical triazolyl C-H···Cl(-) hydrogen bonding. All but one complex showed no metal-based luminescence at room temperature, while all of the Pt(ii) complexes displayed luminescence at 77 K. The electrochemistry of the Ru(II) complexes was also studied and these complexes were found to have higher oxidation potentials than analogous compounds. The redox behaviour of [RuL2](2+) complexes with both 1 and 2 was nearly identical, while [Ru·1Cl2(DMSO)] was oxidised at significantly lower potential. We also show that the Ru(II) complex of 2, [Ru·2(2)](PF6)Cl, gave rise to the formation of a metallo-supramolecular gel, the morphology of which was studied using scanning electron and helium ion microscopy.


Assuntos
Complexos de Coordenação/química , Géis/química , Piridinas/química , Triazóis/química , Cristalografia por Raios X , Ligação de Hidrogênio , Irídio/química , Ligantes , Luminescência , Modelos Moleculares , Níquel/química , Oxirredução , Platina/química , Rutênio/química
13.
Inorg Chem ; 53(4): 1867-79, 2014 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-24354305

RESUMO

The combination of lanthanides and nanoparticles to develop new hybrid nanomaterials has become a highly topical area of research in the field of sensing, biomedical imaging, drug delivery, etc. However, these novel nanomaterials have to be carefully designed to ensure that the unique properties conveyed by each component, i.e., lanthanide ions and nanoparticles, are maximized and not negatively affected by one another. In this Forum Article, the main advances in the design of lanthanide-based nanoparticles will be discussed, with the first part focusing on the design of gadolinium(III)-based nanoparticles and their use as magnetic resonance imaging agents. The second part will then describe the main and most recent designs of luminescent lanthanide-based nanoparticles and their applications as sensors or imaging agents, with a special emphasis on our contribution to this area.


Assuntos
Elementos da Série dos Lantanídeos/química , Luminescência , Imagem por Ressonância Magnética , Imagem Molecular/métodos , Nanopartículas/química
14.
Chemistry ; 19(48): 16181-6, 2013 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-24174126

RESUMO

"Trinity Sliotar" family: Chiral ligands containing pyridyl and naphthalene moieties were synthesized and characterized. These ligands were successfully used for the synthesis of Eu(III) bundles where chirality of the ligand is successfully transferred onto the lanthanide centre resulting in circularly polarized red luminescence.


Assuntos
Európio/química , Elementos da Série dos Lantanídeos/química , Luminescência , Naftalenos/síntese química , Piridinas/síntese química , Isomerismo , Ligantes , Estrutura Molecular , Naftalenos/química , Piridinas/química , Estereoisomerismo
15.
ACS Nano ; 7(6): 4838-45, 2013 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-23663045

RESUMO

In this article, we examine the phenomenon of single-crystal halide salt wire growth at the surface of porous materials. We report the use of a single-step casting technique with a supramolecular self-assembly gel matrix that upon drying leads to the growth of single-crystal halide (e.g., NaCl, KCl, and KI) nanowires with diameters ~130-200 nm. We demonstrate their formation using electron microscopy and electron-dispersive X-ray spectroscopy, showing that the supramolecular gel stabilizes the growth of these wires by facilitating a diffusion-driven base growth mechanism. Critically, we show that standard non-supramolecular gels are unable to facilitate nanowire growth. We further show that these nanowires can be grown by seeding, forming nanocrystal gardens. This study helps understand the possible prefunctionalization of membranes to stimulate ion-specific filters or salt efflorescence suppressors, while also providing a novel route to nanomaterial growth.


Assuntos
Nanotecnologia/métodos , Nanofios/química , Sais/química , Európio/química , Géis , Porosidade
16.
Inorg Chem ; 51(19): 10158-68, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-22974321

RESUMO

A novel near-infrared (NIR) emissive lanthanide-based zinc sensor was designed, based on the self-assembly in aqueous solution between the nonemissive coordinatively unsaturated Yb(III) cyclen complex 2·Yb and the sulfonated 8-hydroxyquinoline (8-HQS) chromophore, which was employed as a sensitizing antenna. The resulting ternary complex, 2·Yb·8-HQS, displayed metal-centered emission in the NIR range upon excitation of the antenna with high quantum yield of Q = 0.23 ± 0.03% in pH 7.4 buffered aqueous solution; demonstrating efficient sensitization from 8-HQS. The addition of zinc led to quenching of the NIR emission as a result of the dissociation of the luminescent ternary 2·Yb·8-HQS complex, where the 8-HQS antenna was displaced from the Yb(III) center in favor of the formation of more stable chelates with Zn(II). These newly formed Zn(II) complexes were shown to exhibit strong green fluorescence; allowing for the simultaneous sensing of Zn(II) both within the visible and the NIR regions at physiological pH in competitive media. Furthermore, 2·Yb·8-HQS was shown to be able to detect Zn(II) with good selectivity and in a reversible manner, even in the presence of competitive group (I) and (II) metal ions as well as in the presence of several biologically important d-metal ions.


Assuntos
Complexos de Coordenação/química , Compostos Heterocíclicos/química , Substâncias Luminescentes/química , Oxiquinolina/química , Itérbio/química , Zinco/análise , Medições Luminescentes/métodos
17.
Angew Chem Int Ed Engl ; 51(29): 7208-12, 2012 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-22689455

RESUMO

Eu(III), the last piece in the puzzle: Europium-induced self-assembly of ligands having a C(3)-symmetrical benzene-1,3,5-tricarboxamide core results in the formation of luminescent gels. Supramolecular polymers are formed through hydrogen bonding between the ligands. The polymers are then brought together into the gel assembly through the coordination of terpyridine ends by Eu(III) ions (blue dashed arrow: distance between two ligands in the strand direction).

18.
Org Biomol Chem ; 10(2): 314-22, 2012 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-22071980

RESUMO

The design and synthesis of dinuclear-lanthanide complexes possessing triazole-based bridges, formed by using copper catalysed 1,3-cycloaddition reactions between heptadentate alkyne functionalised cyclen europium or terbium complexes and di-azides (CuAAC reactions), are described. While this click reaction worked well for the formation of the homo-Eu(III) and Tb(III) bis-tri-arm cyclen N,N-dimethyl acetamide complexes, 2Eu and 2Tb, and for the homo-Eu(III) chiral N-methylnaphthalene based complexes 3Eu (S,S,S) and 4Eu (R,R,R), the formation of the Eu(III) complex of the primary amide analogue of 2, namely 1Eu, was not successful, clearly demonstrating the effect that the nature of the pendant arms has on this reaction. Furthermore, the click reactions between the free alkyne cyclen bis-derivatives (5-8) and the di-azide were unsuccessful, most likely due to the high affinity of the cyclen macrocycles for Cu(II). The Eu(III) complexes of 2-4 and 2Tb all gave rise to sensitised metal ion centred emission upon excitation of the triazole or the naphthalene antennae in methanol solution, and their hydration states were determined, which showed that while the Eu(III) mono-nuclear complexes had q ∼ 2, the click products all had q ∼ 1. In the case of 3Eu (S,S,S) and 4Eu (R,R,R), the circular polarised emission (CPL) was also observed for both, demonstrating the chiral environment of the lanthanide centres.


Assuntos
Amidas/química , Azidas/química , Cobre/química , Compostos Heterocíclicos/química , Elementos da Série dos Lantanídeos/química , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Catálise , Cátions/síntese química , Cátions/química , Química Click , Luminescência , Medições Luminescentes , Estrutura Molecular
19.
Chem Commun (Camb) ; 47(24): 6810-2, 2011 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-21589967

RESUMO

1·Eu·BPS was developed as a luminescent lanthanide sensor for use in displacement assays for detection of d-metal ions by monitoring the changes in the europium emission, which was quenched for iron(II), with a detection limit of ∼10 pM (0.002 µg L(-1)) for Fe(II) in buffered pH 7.4 solution.


Assuntos
Európio/química , Compostos Heterocíclicos/química , Íons/análise , Medições Luminescentes/métodos , Metais/análise , Técnicas Biossensoriais/métodos , Tampões (Química) , Concentração de Íons de Hidrogênio , Limite de Detecção
20.
Inorg Chem ; 48(23): 11123-30, 2009 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-19891422

RESUMO

Tetradentate Schiff bases (H(2)L(i)), derivatives of salicylic aldehyde (H(2)L(1), H(2)L(2)) or o-vanillin (H(2)L(3), H(2)L(4)) with ethylenediamine or o-phenylenediamine as a bridge, and their zinc complexes were studied experimentally and theoretically in view of their possible application as emitters in organic light emitting diodes (OLEDs). The composition of thin films of the complexes was analyzed using a combination of different experimental and molecular modeling techniques taking into account changes in the Gibbs free energy of dehydration and dimerization reactions. The absorption spectra of the initial Schiff bases were investigated in methanol solutions, while the absorption spectra of their zinc complexes were investigated in thin films. Experimental results of elemental analysis, IR spectroscopy, laser desorption/ionization mass spectrometry (LDI MS), and X-ray diffraction as well as theoretical analysis of electronic absorption spectra by the quantum-chemical TD DFT method demonstrate that thin films of the zinc complexes contain binuclear anhydrous molecules. This conclusion should be taken into account when considering both transport and luminescence properties of these complexes in OLED heterostructures. A comparison of the results of CIS, TD DFT/PBE, and TD DFT/PBE0 calculations reveals the crucial importance of the inclusion of the exact exchange in the E(XC) functional for the further correct description of potential energy surfaces of excited states for the systems studied.


Assuntos
Elétrons , Modelos Químicos , Compostos Organometálicos/química , Teoria Quântica , Bases de Schiff/química , Zinco/química , Cristalografia por Raios X , Ligantes , Modelos Moleculares , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrofotometria Infravermelho , Termodinâmica
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