Phosphorhydrazone Dendrimers Research Articles

Interplay between Nanoparticles and Phosphorus Dendrimers, and Their Properties.

This review presents the state of the art of interactions between two different families of nanoobjects: nanoparticles-mainly metal nanoparticles, and dendrimers-mainly phosphorhydrazone dendrimers (or dendrons). The review firstly presents the encapsulation/protection of existing nanoparticles (organic or metallic) by phosphorus-based dendrimers and dendrons. In the second part, several methods for the synthesis of metal nanoparticles, thanks to the dendrimer that acts as a template, are presented. The properties of the associations between dendrimers and nanoparticles are emphasized throughout the review. These properties mainly concern the elaboration of diverse types of hybrid materials, some of them being used as sensitive chemosensors or biosensors. Several examples concerning catalysis are also given, displaying in particular the efficient recovery and reuse of the catalytic entities.

Dendrimers Functionalized with Palladium Complexes of N-, N,N-, and N,N,N-Ligands.

Pyridine, pyridine imine, and bipyridine imine ligands functionalized by a phenol have been synthesized and characterized, in many cases by X-ray diffraction. Several of these N-, N,N-, and N,N,N,-ligands have been grafted onto the surface of phosphorhydrazone dendrimers, from generation 1 to generation 3. The complexation ability of these monomers and dendrimers towards palladium(II) has been assayed. The corresponding complexes have been either isolated or prepared in situ. In both cases, the monomeric and dendritic complexes have been tested as catalysts in Heck couplings and in Sonogashira couplings. In some cases, a positive dendritic effect has been observed, that is, an increase of the catalytic efficiency proportional to the dendrimer generation.

Phosphorus Dendrimers as Nanotools against Cancers.

This review concerns the use of dendrimers, especially of phosphorhydrazone dendrimers, against cancers. After the introduction, the review is organized in three main topics, depending on the role played by the phosphorus dendrimers against cancers: (i) as drugs by themselves; (ii) as carriers of drugs; and (iii) as indirect inducer of cancerous cell death. In the first part, two main types of phosphorus dendrimers are considered: those functionalized on the surface by diverse organic derivatives, including known drugs, and those functionalized by diverse metal complexes. The second part will display the role of dendrimers as carriers of anticancer “drugs”, which can be either small molecules or anticancer siRNAs, or the combination of both. In the third part are gathered a few examples of phosphorhydrazone dendrimers that are not cytotoxic by themselves, but which under certain circumstances induce a cytotoxic effect on cancerous cells. These examples include a positive influence on the human immune system and the combination of bioimaging with photodynamic therapy properties.

Ferrocenyl Phosphorhydrazone Dendrimers Synthesis, and Electrochemical and Catalytic Properties.

The discovery of ferrocene is often associated with the rapid growth of organometallic chemistry. Dendrimers are highly branched macromolecules that can be functionalized at will at all levels of their structure. The functionalization of dendrimers with ferrocene derivatives can be carried out easily as terminal functions on the surface, but also at the core, or at one or several layers inside the structure. This review will focus on phosphorhydrazone dendrimers functionalized with ferrocene derivatives, on the surface, at the core, at all layers or within a single layer inside the structure. The first part will describe the synthesis; the second part will concern the electrochemical properties; and the last part will give several examples concerning catalysis, with complexes of ferrocenyl phosphines used as terminal functions of dendrimers.

Fluorescent Phosphorus Dendrimers: Towards Material and Biological Applications.

Fluorescent derivatives of phosphorhydrazone dendrimers are reviewed. Diverse types of fluorophores have been used, such as pyrene, naphthol, anthracene, dansyl, diketone, phthalocyanine, maleimide, julolidine, rhodamine, fluorescein, or fluorene derivatives. The fluorescent groups can be located either as terminal groups on the surface, at the core, linked to the core (off-center), or to the branches of the dendritic structure. After fundamental research on their synthesis, these compounds have been used in the fields of catalysis, nanomaterials, OLEDs, sensors and biology/nanomedicine, in particular for monitoring transfection, or for their anti-inflammatory or anti-cancer properties.

Which Dendrimer to Attain the Desired Properties? Focus on Phosphorhydrazone Dendrimers.

Among the six Critical Nanoscale Design Parameters (CNDPs) proposed by Prof. Donald A. Tomalia, this review illustrates the influence of the sixth one, which concerns the elemental composition, on the properties of dendrimers. After a large introduction that summarizes different types of dendrimers that have been compared with PolyAMidoAMine (PAMAM) dendrimers, this review will focus on the properties of positively and negatively charged phosphorhydrazone (PPH) dendrimers, especially in the field of biology, compared with other types of dendrimers, in particular PAMAM dendrimers, as well as polypropyleneimine (PPI), carbosilane, and p-Lysine dendrimers.

Engineering CNDP’s of dendrimers containing phosphorous interior compositions to produce new emerging properties

Phosphorus-containing dendrimers are defined as dendrimers having at least one phosphorus atom at each branching point. In this review, we will show how phosphorhydrazone dendrimers can be modified at will at the level of the core and of the branches, to afford specific properties, such as fluorescence to image biological events. Accelerated methods of synthesis of phosphorus (one step for one generation) will be also displayed, as well as the specific reactivity of P=N–P=S linkages obtained in most of these accelerated method of synthesis, which has led to particularly original dendritic architectures, such as dendrons included in dendrimers. Finally, we will display how modifications of the internal structure of a series of dendrimers having the same type and number of terminal functions can deeply modify their biological anti-inflammatory properties. Among the six critical nanoscale design parameters (CNDP), we will show how two of them, i.e., architecture and elemental composition, have been particularly engineered to modify phosphorus-containing dendrimers, in order to fulfill the desired properties.

Dual properties of water-soluble Ru-PTA complexes of dendrimers: Catalysis and interaction with DNA

Phosphorhydrazone dendrimers ended by PTA (1,3,5-triaza-7-phosphaadamantane) derivatives are used for the complexation of ruthenium. The corresponding complexes, either isolated (synthesized ex situ, i.e. preformed) or generated in situ are used as catalysts for the hydration of phenylacetylene in various conditions (ex situ or in situ, quantities, temperature, duration, co-catalyst or not, recycling). The same preformed complexes are tested for their interaction with supercoiled DNA, to afford relaxed DNA.

Ordered Layered Dendrimers Constructed from Two Known Dendrimer Families: Inheritance and Emergence of Properties.

A new concept is presented, namely the synthesis of dendrimers intrinsically composed in alternation of building blocks pertaining to two known families of dendrimers: phosphorhydrazone dendrimers and triazine-piperazine dendrimers. These mixed dendrimers with layered controlled architecture inherit their easy (31) P NMR characterization and their thermal stability from the phosphorhydrazone family, and their decreased solubility from the triazine-piperazine family. However, they have also their own and original characteristics. Both parent families are white powders, whereas the mixed dendrimers are yellow, orange, or red powders, depending on the generation. DFT calculations were carried out on model dendrons to understand these special color features. Remarkably, these dendrimers incorporating redox-active organic entities allow for the first time the monitoring of the growth of an organic dendrimer by electrochemistry while highlighting an even-odd generation behavior.

Inorganic dendrimers: recent advances for catalysis, nanomaterials, and nanomedicine

Dendrimers are hyperbranched polymers having a perfectly defined structure because they are synthesized step-by-step in an iterative fashion, and not by polymerization reactions. Some dendrimers are considered as inorganic, as they possess inorganic atoms at each branching point. Among numerous examples, two families of inorganic dendrimers have emerged as particularly promising: silicon-containing dendrimers, particularly carbosilanes, and phosphorus-containing dendrimers, particularly phosphorhydrazones. This tutorial review will display the main properties of both families of dendrimers in the fields of catalysis, materials and biology/nanomedicine. Emphasis will be put on the most recent and promising examples.

Biological properties of water-soluble phosphorhydrazone dendrimers

Dendrimers are hyperbranched and perfectly defined macromolecules, constituted of branches emanating from a central core in an iterative fashion. Phosphorhydrazone dendrimers constitute a special family of dendrimers, possessing one phosphorus atom at each branching point. The internal structure of these dendrimers is hydrophobic, but hydrophilic terminal groups can induce the solubility of the whole structure in water. Indeed, the properties of these compounds are mainly driven by the type of terminal groups their bear; this is especially true for the biological properties. For instance, positively charged terminal groups are efficient for transfection experiments, as drug carriers, as anti-prion agents, and as inhibitor of the aggregation of Alzheimer's peptides, whereas negatively charged dendrimers have anti-HIV properties and can influence the human immune system, leading to anti-inflammatory properties usable against rheumatoid arthritis. This review will give the most representative examples of the biological properties of water-soluble phosphorhydrazone dendrimers, organized depending on the type of terminal groups they bear.