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Dendrimers are highly branched macromolecules possessing, in most cases, identical terminal functions. However, it is sometimes desirable to have two types of surface functions in order to fulfil specific properties. The stochastic functionalization is frequently used for such purposes, but the presence of an uncontrolled number of each type of terminal function, albeit acceptable for research purposes, has no practical use. Thus, it is highly desirable to find strategies suitable for the precise grafting of two different functional groups on the surface of dendrimers. The easiest way, and the most widely used, consists in using a bifunctional monomer to be grafted to all of the surface functions of the dendrimers. Two other strategies are known but are rarely used: the modification of an existing function, to generate two functions, and the sequential grafting of one function then of a second function. The three methods are illustrated in this review with polyphosphorhydrazone (PPH) dendrimers, together with their properties as catalysts, for materials, and as biological tools. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Catalytic dendrimers are soluble but can be easily recovered, mainly by precipitation, and re-used. • Catalytic phosphorus dendrimers outperform the corresponding monomers in terms of yield and enantioselectivity. • The leaching of metal is drastically reduced when using phosphorus dendrimeric catalysts. • Dendrimers constitute a greener and safer alternative in homogeneous catalysis. Abstract Dendrimers are highly branched macromolecules, which have properties in many different fields, in particular for catalysis. This review presents an exhaustive view about complexes of phosphorus-containing dendrimers (having a phosphorus atom at each branching point), used as homogeneous catalysts in a range of reactions. First, catalysed reactions for C–C bonds formation using Pd, Rh, Ru, or Sc complexes will be displayed; then formation of C–O and C–N bonds using Cu complexes as catalysts will be shown. At the end, miscellaneous reactions catalysed without metal (organocatalysis) will be displayed. Despite their size, dendrimers are generally soluble in the reaction media, thus they afford homogeneous catalysts. However, their size is by far larger than the size of the reagents and products, thus they are generally easily separated, simply by adding a solvent in which the products are soluble, but not the dendrimers. The recovery and reuse of dendrimers (recycling) is an important advantage compared to classical monomeric catalysts, which will be emphasized in this review, together with the so-called dendrimer (or dendritic) effect, which is an enhancement of a property when the size of the dendrimer increases. [ABSTRACT FROM AUTHOR]

Abstract: In order to shorten the long and tedious synthesis of dendrimers, several improvements have been proposed. This paper is a review of the improved methods recently published concerning the synthesis of phosphorus-containing dendrimers. It describes first the synthesis of hyperbranched polymers and their comparison with real dendrimers obtained from the same monomer. Then, the influence of the modification of the core of dendrimers is shown. In a third part, the use of dendrons is illustrated by several examples; they allow for instance to built a generation 8 directly from a generation 3 dendrimer. The last part describes the use of branched monomers of types AB2 and CD2, in which A reacts only with D and B reacts only with C. These reactions do not need any protecting groups, and the only by-products are H2O and N2. Using these monomers, the 4th generation is obtained in only four steps, instead of 8 for classical methods. This method has been improved by using more branched monomers AB5 and CD5, built from the cyclotriphosphazene. In this case, a dendrimer having 750 end groups is obtained in only three steps. The A (NH2), B (PPh2), C (N3) and D (CHO) functions are identical in all cases, and they allow a real “Lego” chemistry, as shown by the synthesis of CA2 and DB2 monomers, also used for the accelerated synthesis of dendrimers. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: A series of densely functionalized dendrimers is synthesized using two branched monomers of type AB2 and CD2, in which the A function (NH2) reacts with D (CHO) and the B function (Cl) reacts with C (OH). The reaction has been carried out up to the fourth generation possessing 96 end groups and has been obtained in only four steps. [Copyright &y& Elsevier]

Phosphorus-containing dendrimers are attractive carriers for the delivery of bioactive molecules due to their very particular architecture, globular shape and chemical and physical properties. Herein we report a simple synthetic approach of ethacrynic acid derivatives loaded-phosphorus dendrimers by symmetrical grafting of ethacrynic acid analogues by nucleophilic substitution of each chlorine of P(S)Cl 2 end groups. We report also for the first time an unsymmetrical grafting of two different phenol derivatives by a selective substitution of one chlorine of P(S)Cl 2 end group followed by the grafting of the second phenol. [ABSTRACT FROM AUTHOR]