1,721,104 research outputs found
Dendrimers with electroactive units in the core or in each branching centre
No full textInterest in dendrimers is mostly focused on their capability of performing specific functions which, in their turn, derive from the possibility of incorporating in predetermined sites of the structure selected functional groups ('pieces of information'). From a topological viewpoint we can distinguish dendrimers containing electroactive units (a) in the core, (b) in the branches, (c) in the surface, (d) in the core and in the branches, (e) in the core and in the surface, (f) in the branches and in the surface, and (g) in the core, branches and surface. In this article we review the behaviour of dendrimers with electroactive units buried in the core and dendrimers with electroactive units in each branching centre investigated in our laboratory. © 2003 Académie des sciences. Published by Éditions scientifiques et médicales Elsevier SAS. All rights reserved
Amine functionalised silicon nanocrystals with bright red and long-lived emission
Full text linkWhen functionalised with amines, silicon nanocrystals (SiNCs) are known to have surface-state emission with loss of colour tunability, low quantum yield and short nanosecond lifetimes. These changes in optical properties are produced by direct amine bonding on the silicon surface. In this article, secondary amine functionalised SiNCs with bright, red (λmax = 750 nm) and long-lived emission (τ ca. 50 μs) are reported for the first time via a three-step synthetic approach. These SiNCs are colloidally stable in several polar solvents and can be further functionalised by reaction with carboxylic acid groups. We proved the feasibility of further functionalization with pyrene butyric acid: ca. 40 pyrene units per nanoparticle were attached via amide bond formation. The resulting hybrid system works as a light-harvesting antenna: excitation of pyrene units at 345 nm results in sensitised emission at 700 nm by the silicon core. This journal i
Tetrachromophoric Systems Based On Rigid Tetraphenylmethane (TPM) and Tetraphenylethylene (TPE) Scaffolds
Full text linkTetraphenylmethane (TPM) and tetraphenylethylene (TPE) are among the most common rigid molecular architectures able to spatially arrange four peripheral functional groups. The aim of this Review is to provide a thorough description of the properties that supramolecular systems consisting of four chromophores (common supramolecular motifs, ligands, redox centers and conventional luminophores such as polypyridyl ligands, viologens, and azobenzene units) attached to TPM and TPE cores can show. Specifically, the photophysical properties of these molecules as well as the electronic interactions of the chromophores either in the ground or in the excited states will be highlighted and discussed, outlining the relationship among cores and outer subunits
A turn-on phosphorescent sensor of Pb2+ in water by the formation of a coordination polymer
No full textHexakis(phenylthio)benzene compounds carrying six carboxylic acid groups at their periphery combine aggregation-induced phosphorescence, water-solubility and metal-binding properties: the para-isomer is a selective and sensitive turn-on phosphorescent sensor of Pb2+ ions in water
Light-harvesting antennae based on copper indium sulfide (CIS) quantum dots
Full text linkCopper indium sulfide quantum dots (CIS QDs) and their core-shell analogues (CIS@ZnS QDs) were functionalized with pyrene chromophores via a dihydrolipoamide bifunctional binding moiety: UV excitation of the pyrene chromophores resulted in sensitized emission of the CIS core because of an efficient energy transfer process; the core-shell hybrid system exhibits a 50% increased brightness when excited at 345 nm
Ruthenium tris(bipyridine) complexes: Interchange between photons and electrons in molecular-scale devices and machines
Full text linkThis review deals with a very peculiar molecule, [Ru(bpy)3]2+ (bpy: 2,2′-bipyridine), and its interaction with photons and electrons. We summarize the properties that make [Ru(bpy)3]2+ and related compounds a unique family of “clever” molecules which find application as components of chemical species capable of processing optical and electrical signals to perform a variety of interesting functions. Examples discussed in the article, that showcase the realization of these concepts with molecular and supramolecular systems, include molecular wires, switches, antennas and mechanical machines
Photocontrolled self-assembly of azobenzene nanocontainers in water: Light-triggered uptake and release of lipophilic molecules
No full textAn easy to synthesize azobenzene based amphiphile spontaneously self-assembles into monodisperse nanoaggregates in water. The large difference in the critical aggregation concentration between the E and Z stereoisomeric forms enables photocontrol of its aggregation state over a wide concentration range: Light-triggered release and uptake of lipophilic molecules is achieved in aqueous solution
Light-harvesting dendrimers
No full textDendrimers are well-defined, tree-like macromolecules, with a high degree of order and the possibility to contain selected chemical units in predetermined sites of their structure. Dendrimers are currently attracting the interest of many scientists because of their unusual chemical and physical properties and the wide range of potential applications. It is possible to design and synthesize dendrimers containing a variety of chromophoric groups organized in the dimensions of time, energy and space so as to obtain efficient light-harvesting devices that can be useful for solar energy conversion and other purposes
- …
