Luminescent Dendrimers. Recent Advances

Abstract

Luminescent dendrimers are currently attracting much attention since coupling luminescence and dendrimer research topics can lead to valuable new functions. Indeed, luminescence is a valuable tool to monitor both basic properties and possible applications (sensors, displays, lasers), and dendrimers are macromolecular compounds exhibiting a well-defined chemical structure with the possibility of containing selected chemical units in predetermined sites and of encapsulating ions or neutral molecules in their internal dynamic cavities. In this paper we will review recent advances in this field focusing our attention on their properties in fluid solution related to light harvesting, changing the "color" of light, sensing with signal amplification, quenching and sensitization processes, shielding effects, elucidation of dendritic structures and superstructures, and investigation of dendrimer rotation in solution.

Internal Dynamics of Dendritic Molecules Probed by Pyrene Excimer Formation

“…Fluorescence resonance energy transfer (FRET), energy hopping or migration, and electron transfer between a donor and an acceptor are all photophysical processes whose efficiency depends strongly on the distance between the donor and acceptor [135][136][137]. The design of dendrimers used for this type of applications consists in placing many donors at the dendrimer periphery and a single acceptor molecule at the dendrimer focal point [3,36,[39][40][41][42][43][44][120][121][122][123]125]. As the dendrimer generation increases, the efficiency of the photophysical process of interest decreases according to the increased distance separating the donor from the acceptor [135][136][137].…”

“…The exquisite level of synthetic control achieved over the molecular architecture of dendrimers, which was demonstrated more than 25 years ago by the preparation of polyamide and poly(amido amine) (PAMAM) dendrimers by Newkome [1] and Tomalia [2], respectively, has made these macromolecules key elements in a broad range of applications such as for light harvesting devices [3,4], in the biomedical field [5,6], for catalysis [7,8], or as sensors [9,10]. One essential feature afforded by the cascade synthesis of dendrimers [11] is the exponential increase of both the number of reactive end groups and the dendrimer mass with increasing generation number as ~f G where f and G are the branch-juncture multiplicity (f > 1) and G is the generation number.…”

Design of Fluorescent Materials for Chemical Sensing

“…3). Luminescent dendrimers have been recently reviewed by Balzani et al 94 Dendritic structures containing luminescent metal complexes, fluorescent organic chromophores, porphyrins and fullerenes have been reported. 94 Signal amplification processes in these dendrimers have been well characterized 95 and could be advantageous for sensor design.…”

“…Luminescent dendrimers have been recently reviewed by Balzani et al 94 Dendritic structures containing luminescent metal complexes, fluorescent organic chromophores, porphyrins and fullerenes have been reported. 94 Signal amplification processes in these dendrimers have been well characterized 95 and could be advantageous for sensor design. In the field of chemical sensing, it has been demonstrated that luminescent dendrimers could be used for chiral amino alcohols, [96][97][98] and metal ion sensing.…”

Light-Harvesting in Carbonyl-Terminated Phenylacetylene Dendrimers: The Role of Delocalized Excited States and the Scaling of Light-Harvesting Efficiency with Dendrimer Size

“…If the active units are conjugated molecules that absorb light and the core is an energy acceptor or trap, then such dendrimers can be used as light-harvesters, 1 in analogy to natural photosynthetic systems. 2,3 Such systems have received considerable attention as light-harvesting elements for solar energy conversion. The goal is to build a molecule with a huge effective absorption cross section, where the initially absorbed energy is then transferred from the peripheral donors to the acceptor (trap) at the base of the dendrimer.…”