Wet Adsorption of a Luminescent Eu^III complex on Carbon Nanotubes Sidewalls

Abstract

A EuIII complex, tris‐dibenzoylmethane mono‐1,10‐phenanthroline‐europium(III) [Eu(DBM)3(Phen)], can be easily adsorbed in situ via hydrophobic interactions to single‐walled carbon nanotube (SWNT) surfaces from a methanol solution. The EuIII‐containing material has been comprehensively characterized via thermogravimetric analysis (TGA), UV‐vis‐NIR absorption and luminescence spectroscopy, Raman spectroscopy, atomic force microscopy (AFM), high‐resolution transmission electron microscopy (HR‐TEM)), Z‐contrast scanning transmission electron microscopy (STEM) imaging, and energy dispersive X‐ray spectroscopy (EDS). The photophysical investigations revealed that the presence of a SWNT framework does not affect the lanthanide‐centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the EuIII ions. Such straightforward synthetic route leads to the preparation of luminescent SWNTs without significantly affecting the electronic and structural properties of the carbon framework, opening new possibilities of designing new classes of CNTs for biomedical applications.

Synthesis and photoluminescence properties of heteroleptic Eu3+, Tb3+ and Tm3+ complexes

“…The scarce influence of the carbazole moiety on the luminescence intensity (comparison between 1-Eu and 2-Eu) is due to the unfavorable partition of the absorbed light at 325 nm between dbm and carbazole (around 10:1). Furthermore, 2-Eu showed similar PL intensity both as powder and in polycarbonate matrix, confirming that the internal f-f radiative transitions of the lanthanide ions are scarcely affected by the external environment [38]. 3-Eu, involving three hfa groups, showed an appreciable PL performance in solution but no enhancement of the PL intensity has been detected by passing to the solid state.…”

Coordination chemistry on carbon surfaces

“…Another reported strategy consists in the prior anchoring of a functionalized pyrene molecule, acting as a bridging unit, interacting with SWCNTs through the pyrene ring and strongly coordinating to the zinc center of the metallomacrocyle via a nitrogen atom of the functional group [163]. Apart from pyrene, that appears as a polyaromatic fragment of choice for the development of -interactions; other aromatic moieties like naphthalene [169,170,173], 1,10-phenanthroline [201][202][203] or even cyclopentadienyl (Cp) rings [204][205][206] have been successfully used for non-covalent immobilization of transition metal complexes onto graphitic surfaces and are presented in Table 12. Theoretical calculations using the surface integrated molecular orbital/molecular mechanics method were applied to the SWCNT/zirconocene system.…”

Synthesis and Photoluminescence Properties of Heteroleptic Europium(III) Complexes with Appended Carbazole Units

“…In polycarbonate matrix, the absolute emission quantum yields are difficult to assess with acceptable accuracy, but the measured lifetimes (consistent with values reported in the literature for Eu III complexes in rigid media) [27] can provide quantitative information. Indeed, it is possible to evaluate the emission quantum yield by means of Equation (1), where τ obs and τ 0 are the observed and the radiative [18,28,29] lifetimes, respectively. Notably, quantum yields as high, as 0.18 and 0.14 are estimated for Eu·dbm·carb·phen and Eu·dbm·carb·bath, respectively.…”

“…[17] However, in spite of the excellent photoluminescence (PL) properties of Eu III materials, bright-red europium-containing electroluminescent (EL) devices with satisfying performance are hardly obtainable because of the poor charge-transporting ability of the lanthanide complexes and the luminescence quenching by matrix vibrations through nonradiative pathways. [18,19] To improve the charge-transporting properties of Eu III complexes to be used in electroluminescent devices, a suitable strategy would involve doping with electron/hole-transporting molecules, such as biphenyl-p-(tert-butyl)phenyl-1,3,4-oxadiazole (PBD), N,NЈ-diphenyl-N,NЈ-bis(3-methylphenyl)-1,1Ј-biphenyl-4,4Ј-diamine (TPD) or 4,4Ј-N,NЈ-ane solution and in solid matrix show that the carbazole moiety is a better sensitizer for the metal-centred emitting states of the Eu III ion compared to the dibenzoylmethane and phenanthroline units. Furthermore, the charge-transporting properties of the carbazole moieties appear to be appealing when integrated into the emitting units.…”