Anisometric Ln(III) Complexes with Efficient Near-IR Luminescence

Recent studies in development of near-infrared luminophores focus on overcoming their disadvantages such as low quantum efficiency, limited emission power, and broad emission spectra. Rare earth (RE) elements are promising compounds in this respect as they offer a unique set of optical properties that provide narrow emission spectra and large Stokes shifts. This work reports the results of synthesis and characterization of new anisometric complexes of lanthanide(III) tris(b-diketonates) and 1,10-phenanthroline. These complexes possess light emitting-properties in the near-infrared range. Due to their structural features, these complexes allow production of homogeneous films by spin coating. These films are transparent in the visible and near-infrared ranges (transmission up to 99%). This paper demonstrates advantages of Yb(III), Er(III), and Nd(III) complexes as potential components of highly efficient light-transforming NIR coatings.

АССМОТРЕНИЕ ВЛИЯНИЯ САМОАГРЕГИРОВАНИЯ В НАНОРАЗМЕРНЫХ КЛАСТЕРАХ CDS

Quantum dots, such as cadmium sulfide (CdS), are semiconductor nanocrystals that possess unique optical properties, including wide­range excitation, size­tunable narrow emission spectra and high pho­tostability. The size and composition of quantum dots can be varied to obtain the desired emission prop­erties and make them suitable for various optical and biomedical applications. In this article, the effect of self­aggregation on the electronic absorption spectra and on the dipole moment in CdS nanoparticles is considered using computer modeling methods based on the density functional tight­binding (DFTB). The object of the study is four CdS structures and two models of an aggregated dimer for each cluster. The construction of dimers of cadmium sulfide clusters showed that a higher level of passivation can be achieved in comparison with the initial monomers. In this case, the construction of dimers should occur along the direction of the dipole moment of the monomer in order to minimize it. Therefore, it can be assumed that the dipole moment plays a key role in the formation of trap states in nanosized clusters of cadmium sulfide, and the problem of passivation is reduced to minimizing the dipole moment.

COORDINATION COMPLEX [Eu(μ 2 -OC 2 H 5 )(btfa)(NO 3 ) (phen)] 2 ·phen WITH HIGH LUMINESCENT EFFICIENCY

Experimental results on the bis[(μ 2 -etoxi)(benzoyl trifluoroacetonato)(nitrato)(1,10- phenantroline)europium(III)]1,10-phenantroline europium(III) coordination complex (hereafter, [Eu(μ 2 -OC 2 H 5 )(btfa)(NO 3 )(phen)] 2 ·phen) are described. The complex is characterized by photoluminescence (PL) and infrared spectroscopy. Photoluminescence spectra of the complex exhibit strong emission with specific narrow emission bands associated with the 5 D 0 → 7 F j (j = 0–4) transitions. The pattern of emission band splitting and the luminescence time decay suggest the presence of at least two different sites of the Eu 3+ ion in a low-symmetry environment. The absolute PL quantum yield of the complex is determined to be 49.2%.