Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chem Commun (Camb) ; 59(40): 6044-6047, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37102629

RESUMO

The chiral bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligand 1 was used in the formation of lanthanide di- and triple stranded di-metallic helicates in acetonitrile solution, where the changes in the ground and the Tb(III) excited state properties were used to monitor the formation of these supramolecular structures in situ under kinetic control.

2.
Inorg Chem ; 59(5): 2646-2650, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32049514

RESUMO

Ditopic helicate ligands 1 and 2 were synthesized for the formation of dinuclear EuIII luminescent chiral helical assemblies (Eu2·L3) in competitive organic and protic solvent media. Spectroscopic analysis revealed formation of the 2:3 (Eu2·L3) and 2:2 (Eu2·L2) species in methanolic solutions. Circular dichroism and circularly polarized luminescence (CPL) spectroscopy confirmed the chiral purity of the helical systems, while scanning electron microscopy imaging demonstrated the formation of hierarchical self-assemblies with spherical morphologies.

3.
Dalton Trans ; 48(30): 11317-11325, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31271402

RESUMO

The lanthanide directed self-assembly of chiral amphiphilic 2,6-pyridinedicarboxylic acid based ligands 1 and 2 with various Ln(CF3SO3)3 (Ln = TbIII, SmIII, LuIII, DyIII) salts was studied in CH3CN and evaluated with the expected 1 : 3 and 1 : 1 Ln : Ligand species forming in solution. Ligand chirality was retained and transferred, as depicted by circular dichroism (CD) and circularly polarised luminescence (CPL) measurements (for TbIII and SmIII), to the lanthanide centre upon complexation with high dissymmetry factor values for the SmIII complexes obtained (glum = -0.44 and 0.29 and 0.45 and -0.23 for the 4G5/2→6H5/2 and the 4G5/2→6H7/2 transitions of Sm·13 and Sm·23, respectively). The ability of the complexes to form stable Langmuir monolayers at the air-water interface was also established while Langmuir-Blodgett films of Tb·L3 and Sm·L3 exhibited lanthanide luminescent emission.

4.
Dalton Trans ; 46(19): 6464-6472, 2017 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-28470292

RESUMO

A flexible ditopic ligand 1 containing two N,N,O-tridentate (1,2,3-triazol-4-yl)-picolinamide chelating pockets is reported and the formation of multimetallic architectures is explored in the solid and the solution phase. The self-assembled ZnII complex [Zn4(1)4](ClO4)8 exhibited a folded [2 × 2] square grid supramolecular architecture that selectively assembled in MeCN solution as shown using various spectroscopic techniques. The closely related FeII complex shows equivalent behaviour in the solid state, while a discrete dinuclear species [Cu2(NO3)41]·5MeCN was the sole product observed in the solid state from the reaction between 1 and CuII under similar conditions.

5.
Chem Soc Rev ; 45(11): 3244-74, 2016 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-27137947

RESUMO

Herein some examples of the use of lanthanide ions (f-metal ions) to direct the synthesis of luminescent self-assembly systems (architectures) will be discussed. This area of lanthanide supramolecular chemistry is fast growing, thanks to the unique physical (magnetic and luminescent) and coordination properties of the lanthanides, which are often transferred to the resulting supermolecule. The emphasis herein will be on systems that are luminescent, and hence, generated by using either visibly emitting ions (such as Eu(III), Tb(III) and Sm(III)) or near infrared emitting ions (like Nd(III), Yb(III) and Er(III)), formed through the use of templating chemistry, by employing structurally simple ligands, possessing oxygen and nitrogen coordinating moieties. As the lanthanides have high coordination requirements, their use often allows for the formation of coordination compounds and supramolecular systems such as bundles, grids, helicates and interlocked molecules that are not synthetically accessible through the use of other commonly used templating ions such as transition metal ions. Hence, the use of the rare-earth metal ions can lead to the formation of unique and stable species in both solution and in the solid state, as well as functional and responsive structures.

6.
Langmuir ; 29(36): 11506-15, 2013 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-23980548

RESUMO

The incorporation of chiral amphiphilic lanthanide-directed self-assembled Nd(III) complexes (Nd.13 and Nd.23) into stable Langmuir monolayers, and the subsequent Langmuir-Blodgett film formation of these, is described. The photophysical properties of the enantiomeric pair of ligands 1 and 2 in the presence of Nd(CF3SO3)3 were also investigated in CH3CN solutions using UV-vis, fluorescence, and lanthanide luminescence spectroscopies. Analysis of the resulting self-assembly processes revealed that two main species were formed in solution,1:1 and 1:3 Nd:L self-assembly complexes, with the latter being the dominant species upon the addition of 0.33 equivalents of Nd(III). Excited state lifetime measurements of Nd.13 and Nd.23 in CH3OH and CD3OD and CH3CN were also evaluated. The formation of the self-assembly in solution was also monitored by observing the changes in the circular dichroism (CD) spectra; and large differences were observed between the 1:3 and other stoichiometries in the spectra, allowing for correlation to be made with that seen in the emission studies of these systems. Surface pressure-area and surface pressure-time isotherms evidenced the formation of stable Langmuir monolayers of Nd.13 and Nd.23 at an air-water interface, and the deposition of these monolayers onto a quartz solid substrate (Langmuir-Blodgett films) gave rise to immobilized chiral monomolecular films which exhibited Nd(III) NIR luminescence upon excitation of the ligand chromophore, demonstrating efficient energy transfer to the Nd(III) excided state (sensitized) with concomitant emission centered at 800 and 1334 nm.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Raios Infravermelhos , Elementos da Série dos Lantanídeos/química , Neodímio/química , Ligação de Hidrogênio , Ligantes , Modelos Moleculares , Conformação Molecular , Estereoisomerismo
8.
Dalton Trans ; 40(45): 12056-9, 2011 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-21938292

RESUMO

The reaction between the asymmetrical pyridyl ligands 3 (R) and 4 (S) and Eu(III) in CH(3)CN give rise to the formation of lanthanide luminescent 'half-helicates' in 1 : 3 (Ln:ligand) stoichiometry; the formation of which was observed by monitoring the changes in the ground and the excited state properties of the ligands, and in the time-resolved Eu-centred and the CPL emission.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...