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International audience; 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.

International audience; Two generations of phosphoric dendrimers with piperidine functional groups were synthesized for use in biology and medicine. Neutral samples are soluble in organic solvents but after protonation these dendrimers become water soluble and can be used for biological experiments. The FTIR and FT Raman spectra of two generations of dendrimers Gi constructed from the cyclotriphosphazene core, repeating units OC6H4CHNN(CH3)P(S)< and aminoethylpiperidine end groups NH(CH2)2C5NH11 were recorded. The study of the IR spectra shows that the NH groups form hydrogen bonds. The calculation of the molecular structure and vibrational spectra of the first generation dendrimer was performed by the method of DFT. This molecule has flat, repeating units and a plane of symmetry passing through the core. The calculation of the distribution of potential energy made it possible to classify the bands in the experimental spectra of dendrimers. Amine groups are manifested in the form of a band of NH stretching vibrations at 3389 cm−1 in the IR spectrum of G1. NH+ stretching bands located at 2646 and 2540 cm−1 in the IR spectrum of G2. The stretching vibrations of NH+ groups are noticeably shifted to low frequencies due to the formation of a hydrogen bond with the chlorine atom. The line at 1575 cm−1 in the Raman spectrum of G1 is characteristic for repeating units.

International audience; FT Raman and infrared spectra of phosphotrihydrazone (S)P[N(CH3)N=CH_C6H4_OH]3-(G0) were recorded. This compound is a zero generation phosphorus dendrimer with terminal phenolic groups. Optimal geometry and vibrational frequencies were calculated for G0 using the density functional theory (DFT). The molecule studied has C3 symmetry. In the molecule G0, each_C6H4_CH=N_N(CH3)_P arm is flat. Optimized geometric parameters correspond to experimental data. The core of the dendrimer manifests itself as a band at 647 cm−1 in the Raman spectrum of G0 related to P=S stretching. Phenolic end functions exhibit a well-defined band at 3374 cm−1 in the experimental IR spectrum of G0. The observed frequency of the OH stretching vibrations of the phenolic groups is lower than the theoretical value due to the intermolecular O_H⋯O hydrogen bond. This hydrogen bond is also responsible for the higher intensity of this band in the experimental IR spectrum compared with the theoretical value. DFT calculations suggest full assignment of normal modes. Global and local descriptors characterize the reactivity of the core and end groups.

International audience; The structure of organoclays composed of synthesized phosphorus-based dendrimers, which was endowed with peripheral ammonium groups, and stevensite- or montmorillonite-rich clays was examined using X-ray diffraction, high resolution transmission electron microscopy, thermal analysis and solid-state nuclear magnetic resonance. The interactions between methylene blue (MB) and the organoclays or Na+-saturated clay minerals were investigated. The results showed that both dendrimers adsorbed on Na+-saturated clay minerals by cation exchange, and that the organoclays, particularly those of the first generation dendrimers, were mainly composed of intercalated nanocomposites. As a result of the adsorption of the dendrimers, the clay hydrophilicity reduced and the dehydroxylation temperature of the clay minerals increased. Regarding the adsorption of MB on the organoclays, the results pointed out that MB mainly adsorbed as MB+ and MBH2 +, and the electronic environments of AlIV of montmorillonite and that of AlVI of stevensite were disturbed. For some organoclays, ordered structures were formed, and the Si4 + substituent (Al3 +) left the tetrahedral sheet. The thermodynamic data indicated that MB adsorbed spontaneously (− 11.3 < ∆ G° < − 0.9 kJ/mol) and the uptake of MB by montmorillonite-based organoclays was believed to occur by chemisorption. In contrast, for stevensite-based organoclays MB adsorption seemed to be accomplished by physisorption.

International audience; Phosphorus dendrimers are highly branched macromolecules, built with one phosphorus atom at each branching point. These dendrimers can be functionalized at will on the terminal functions. Grafting as terminal functions ligands suitable for the complexation of copper has been carried out several times, in particular with the aim of using the corresponding complexes as catalysts in a range of reactions, from O-and N-arylations and-vinylations, to the asymmetric benzoylation of linear or cyclic diols. A sequel of this work concerns the study of anticancer activity of analogous dendritic copper complexes.

Dendrimers are hyperbranched macromolecules, having a large number of terminal functions, easily accessible and modifiable to afford the desired properties. Metal complexes of dendrimers are frequently used as catalysts in diverse reactions, but they can be used also as innovative biological tools. This review focusses on the recent advances (last 10 years) of dendritic metal complexes used for bioimaging, essentially in vivo. Three main domains will be covered. The first one concerns luminescent complexes for optical imaging (OI). The second one is the largest one; it concerns magnetic resonance imaging (MRI) contrast agents, mostly based on gadolinium complexes. The third and last domain concerns radioactive dendrimer complexes for single photon emission computed tomography (SPECT), and also for positron emission tomography (PET). Two main radionuclides are used in this context, technetium (99mTc) and indium (111In). Two types of ligands are generally used for all these complexes in the two last domains, diethylenetriaminepentaacetic acid (DTPA), and a cyclic analogue, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and some of their derivatives. These complexes have been used in many cases for in vivo imaging of cancerous tumors in mice or rats.

Poly(phosphorhydrazone) dendrimers constitute a versatile class of dendrimers, which can be functionalized at will at all levels of the structure (surface, core, branches) with various types of ligands (mono-, bi-, multi-dentate ligands), suitable for the complexation of different types of metals, including transition metals, lanthanides, or alkaline earths. This review is organized depending on the type of ligands. The properties of the corresponding complexes have been studied in many cases, and will be given. Most of the properties concern catalysis; a positive dendrimeric effect has been observed in many cases when the generation of the dendrimer increases. In many cases it is possible to recover the catalyst and to reuse it (up to ten times with the same efficiency). Other properties concern the field of materials, with the functionalization of the surface of electrodes, in particular with ferrocene-containing dendrimers, or the elaboration of metallic nanoparticles, and even their organization in dendritic networks. A single example of property in the field of biology is given, but it constitutes a promising result as anti-proliferative agents against cancerous cells.

0301-0104; Abstract The FTIR and FT Raman spectra of the first generation dendrimers, possessing carbamate (G1) or ammonium (G2) terminal groups were studied. The structural optimization and normal mode analysis were performed for dendrimers on the basis of the density functional theory (DFT). These calculations of G2 gave the frequencies of vibrations, infrared intensities and Raman scattering activities for the E- and Z-forms of azobenzene unit. The energy difference between the E- and Z-forms of G2 is 27.36 kcal/mol. The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that dendrimers molecules have a concave lens structure with planar -O-C6H4-CHN-N(CH3)PS, and -O-C6H4-NN-C6H4-CHN-NH-CO-CH2-N fragments and slightly non-planar cyclotriphosphazene core. The experimental IR and Raman spectra of dendrimers G1 and G2 were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The strong band 1605 cm−1 in the IR spectra show marked changes of the optical density in dependence of substituents in the aromatic ring. The differences in the IR and Raman spectra of G2 for the E- and Z-forms of azobenzene units were cleared up. During structural isomerization of azobenzene units, redistribution of band intensities appears to a much higher extent than frequency shifts.

0141-8130; The inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) is the first step in checking whether new compounds can be considered as drugs for treating neurodegenerative diseases. The effect of viologen-phosphorus dendrimers on AChE and BChE activities was studied. The results show that the effects on the cholinesterase activities depend on dendrimer type and size. Viologen dendrimers can interact with the enzymes in two ways: they can bind either to a peripheral site of the enzyme or to amino acids located near the active site, inhibiting catalysis by both cholinesterases. All tested non-toxic viologen-phosphorus dendrimers inhibited the activities of both cholinesterases, showing their potential as new drugs for treating neurodegenerative diseases.

The aim of this work was to study the effect of phosphorus-containing dendrimers (generations G3 and G4) on the fibrillation of α-synuclein (ASN). The inhibition of fibril formation (filamentous and aggregates) is a potential therapeutic strategy for neurodegenerative disorders such as Parkinson's and other motor disorder neurodegenerative diseases. The interaction between phosphorus-containing dendrimers and ASN was studied by fluorescence spectroscopy. The decrease in the fluorescence intensity of intrisinic tyrosine was the most marked change in the fluorescence intensity observed upon addition of dendrimers. Furthermore, the effect of dendrimers on ASN fibril formation was studied using circular dichroism (CD) spectroscopy and CD studies were complemented by fluorescence assays using the dye thioflavin T (ThT). The results showed that phosphorus-containing dendrimers G3 and G4 inhibited fibril formation, when they were used in the ASN/dendrimer ratios 1:0.1 and 1:0.5. However, the higher concentrations of dendrimers did not show this effect.

International audience; We present a simple strategy to obtain non-symmetrical polyethylene glycols equipped with telechelic phosphorus-containing dendrimeric moieties having adhesive phosphonate surface functions. The dendronized PEG tails were characterized by means of multi-nucleus NMR. The grafting abilities of model symmetrical PEG compounds equipped with telechelic amino-bis(methylene-dimethylphosphonates) and amino-bis(methylenephosphonic acids) were rapidly screened on plasma treated silicon wafers and activated silica.

The FTIR and FT Raman spectra of the "Janus"-type dendrimers, possessing five carbamate groups on one side and five fluorescent dansyl derivatives on the other side, with amide G(1) and hydrazone G(2) central linkages were studied. These surface-block dendrimers are obtained by the coupling of two different dendrons. The FTIR and FT-Raman spectra of the zero generation dendrons, built from the hexafunctional cyclotriphosphazene core, with five dansyl terminal groups and one carbamate G(0v) and one oxybenzaldehyde function G(0v)' have been recorded. The structural optimization and normal mode analysis were performed for dendron G(0v)' on the basis of the density functional theory (DFT). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that dendron molecule G(0v)' has a concave lens structure with planar -O-C(6)H(4)-CHO fragments and slightly non-planar cyclotriphosphazene core. The experimental IR and Raman spectra of dendron G(0v)' were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The strong band 1597 cm(-1) show marked changes of the optical density in dependence of substituents in the aromatic ring. The frequencies of ν(N-H) bands in the IR spectra reveal the presence of the different types of H-bonds in the dendrimers.

The FTIR and FT-Raman spectra of the first generation dendron built from the cyclotriphosphazene core, five arms O C6H4 CH N N(CH3) P(S) G v 1 ′ have been recorded. The structural optimization and normal mode analysis were performed for dendron on the basis of the density functional theory (DFT). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that G v 1 ′ has a concave lens structure with planar O C6H4 CH N N(CH3) P(S) G v 1 ′ dendron was interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The strong band 1597 cm−1 show marked changes of the optical density in dependence of the aldehyde (−СН О), ester (−OС O−) or azomethyne (−СН N−) substituents in the aromatic ring.

FTIR and FT-Raman spectra of dendron built of the cyclotriphosphazene core with five carbamate and one ester functions (G0) and [2-(4-hydroxyphenyl)ethyl]-carbamic acid tert-butyl ester (C) have been recorded at various temperatures between 16 and 70 °C. The bands of free ν(N–H) and ν(C O) bonds are not observed in the IR spectra of C in the crystalline state and in the melt, and thus association of carbamate groups by hydrogen bonds occur. The frequencies of ν(N–H) and ν(C O) bands in the IR spectra reveal the presence of the different types of H-bonds in the amorphous state of G0. Density functional theory (DFT) calculations of C gave vibrational frequencies and intensity of IR bands for the t-g-, g-g-, tg-, gg-conformers. The most stable is the gg-conformer. The bond lengths, bond angles, frequencies and intensity of bands in the IR spectra of dendron obtained by DFT show the best agreement with experimental data. Relying on DFT calculations a complete assignment of vibrations is proposed for different parts of dendron. The ionization energy IE, electron affinity EA and global softness of G0 are higher than that of C. The most reactive places in C are OH, NH and C O groups. The local softness of C O bond of carbamate group in G0 for nucleophilic attack is lower than that of methylbenzoate group.

Polyelectrolyte multilayer microcapsules are important for a variety of potential applications, and represent a convenient system for studying properties of multilayer films. Recent work explored a post-treatment of such capsules by organic solvents, by reporting a softening. Here we show, that an addition of a very small amount of solvent (THF) to the phosphorus [G3(NH+Et2Cl−)48] dendrimer adsorption solution results, in contrast, in a discernible stiffening of (PSS)/phosphorus dendrimer microcapsules, although it does not affect the multilayer thickness. Our results open new possibilities to tune mechanical properties of multilayer films.

This review emphasizes the role of phosphorus for the elaboration of dendrimers and of various highly sophisticated dendritic structures, and the invaluable role played by 31P NMR for their characterization and to ascertain their purity. A few properties, highlighting the importance of phosphorus are reported at the end of this review.

The FTIR and FT Raman spectra of four generations of phosphorus dendrimers built from cyclotriphosphazene core with terminal oxybenzaldehyde groups have been recorded and analyzed. Their spectral pattern is determined by the ratio T n /R n ( T n – the number of terminal groups, R n – the number of repeating units). This ratio tends to r − 1 (r – branching functionality of repeating unit), and becomes constant, when the generation number is higher than 3–5. Experimental IR and Raman spectra of different generations of dendrimers built of thiophosphoryl and cyclophosphazene cores are very close similar, according theoretical approach. The dependence of band full width at half height in the IR and Raman spectra on generation number and on the number of dendrons is established. Bands assigned to the core, repeating units and terminal groups of dendrimers were separated by the difference spectroscopy method. The rather rigid repeating units with little conformational flexibility define the perfect microstructure of phosphorus-containing dendrimers. FTIR and FT Raman spectroscopies provide the unique detailed information about the structure of technologically relevant materials, which could not be obtained before with any other technique.

Azobenzene derivatives are very attractive for light-driven experiments, due to their easy trans / cis isomerization, which is one of the cleanest photochemical processes known to date. Azobenzenes have been linked in various places to the structure of dendrimers and dendrons. The azobenzene groups can constitute the terminal functions of the dendrimers (or dendrons); a single azobenzene can be located at the core of a dendron or a dendrimer; finally, several azobenzene groups can be incorporated at one or several layers of dendrimers or dendrons. The first part of this review is an exhaustive compilation of all these types of azobenzene-containing dendritic structures. Most dendritic macromolecules possessing azobenzenes in their structure were synthesized with the aim of studying their photo-responsive properties. The influence of the placement of azobenzene groups on the isomerization properties was determined in solution: generally, burying the azobenzene inside the structure induces reluctance to isomerization, especially when the generation increases, but has a larger influence on the size modification. Several dendritic azobenzenes were also studied as thin films, in particular monolayer Langmuir and Langmuir–Blodgett films. Photo-induced alignment was observed for thin films obtained by spin-coating, others were used for holographic experiments. Self-arrangements of photo-responsive dendrimers have resulted in liquid crystalline organizations, vesicles, nano-fibers, and organogels. In addition to these particular properties, some more practical uses were reported such as for molecular imprinting, to trap/release guest molecules, or for drug delivery by cleavage of the N N bond.

FTIR and FT-Raman spectra of phosphorus-containing dendrons built from the hexafunctional cyclotriphosphazene core with five terminal aldehyde ( G 0 ′ ) or P–Cl ( G 0 ) groups and one ester function have been recorded and analyzed. The optimized geometry, frequencies and intensity of IR bands of dendrons were obtained by the density functional theory (DFT). It was found that the internal skeleton of G 0 , G 0 ′ molecules exists in a single stable conformation with slightly non-planar cyclotriphosphazene core. But terminal ester group in G 0 molecule may adopt flat and chair rotational isomers. The flat conformer is 0.04 kcal/mol less stable compared to the chair conformer. The bond lengths and bond angles obtained by DFT show the best agreement with experimental data. Relying on DFT calculations a complete assignment of vibrations is proposed for different parts of dendrons. The calculated frequencies and intensity of bands in the IR spectra of dendrons are found to be in reasonable agreement with the experimental results. Our study reveals that the most reactive site in G 0 is the PCl 2 terminal groups. The local softness of C O bond of benzaldehyde in G 0 ′ is higher than that of methylbenzoate group.

The IR spectra of P(1) phosphorus dendrimer built from an octasubstituted metal-free phthalocyanine core have been recorded in the region 4000-400cm(-1). Besides the phthalocyanine core, P(1) possess also eight C(6)H(4)-CHN-N(CH(3))-P(S) arms and terminal P-Cl groups. The optimized molecular geometry, frequency and intensity of the IR bands have been calculated using density functional theory (DFT). The P(1) molecules exist in a stable conformation with planar C(6)H(4)-CHN-N(CH(3))- fragments and phthalocyanine core. The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. The experimental IR spectrum of P(1) dendrimer was interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The difference IR spectra of molecules built from the thiophosphoryl, cyclotriphosphazene, and phthalocyanine cores with the same repeated units and terminal groups were studied in order to undermine the role of the core functionality on the dendrimer architecture.

The IR and Raman spectra of P 0 ′ and P 4 ′ dendrimers built from an octasubstituted metal-free phthalocyanine core with oxybenzaldehyde terminal groups have been recorded. The phthalocyanine core was used as a probe for analyzing the properties of the internal structure. The structural optimization and normal mode analysis were performed for P 0 ′ dendrimer on the basis of the density functional theory (DFT). It was found that the P 0 ′ molecule exists in a stable conformation with planar phthalocyanine core. The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. The experimental IR spectra of P1 dendrimer were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The difference IR and Raman spectra of molecules built from the thiophosphoryl and phthalocyanine cores with the same repeating units and terminal groups were studied in order to underline the role of the core functionality on the dendrimer architecture.

The IR spectra of second generation dendrimer G2 has been recorded in the region 3500–350 cm−1. The optimised molecular geometry, frequency and intensity of IR bands of G2 have been computed using the density functional theory (DFT) methods. The geometrical parameters and harmonic frequencies, dipole moment, band intensities in the IR spectra of G2 are predicted in a reasonable agreement with experimental data. It was found that the molecule exists in a single stable conformation with planar O C6H4 CH N N(CH3) fragments. All these observations suggest that steric congestion does not disturb the construction of dendrimers even for the highest generations, and that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimer. IR spectroscopy combined with DFT computation provides unique detailed information about the structure of the technologically relevant materials, which could not be obtained before with any other technique.

The various types of dendritic compounds incorporating macrocycle(s) in some part(s) of their molecular architectures are described. As an illustration of such compounds, emphasis is put on those based on phosphorus derivatives. The type and location of the macrocycle(s) in the dendrimer are varied: crown ethers as end groups or as pendant internal groups, tetraazamacrocycles or triazatriolefinic macrocycles as end groups, a phosphorus-containing macrocycle or a phthalocyanine as core. The influence of the dendritic structure on the macrocycle, and conversely of the macrocycle(s) on the dendritic structure is demonstrated in several cases. Some of these compounds possess original properties, such as the detection of diasteroisomers by NMR, the detection of barium salts by electrochemistry, an enhanced fluorescence useful in biological experiments, an increased stability for nanolatexes, or the elaboration of Pd nanoparticles having a catalytic activity.

The FT-IR (400–4000 cm −1 ) spectra of G c 1 ′ generation of phosphorus dendrimer, built from cyclotriphosphazene core, six O C 6 H 4 CH N N(CH 3 ) P(S) G c 1 ′ molecule on the basis of the density functional theory (DFT). It was found that G c 1 ′ molecule has a concave lens structure. The internal skeleton of G c 1 ′ molecules exists in a single stable conformation with planar O C 6 H 4 CH N N(CH 3 ) P(S) O bonds. The optimized geometric bond length and bond angles obtained by using DFT show the best agreement with the experimental data. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimers. The heat capacities and enthalpies of the seven generations of dendrimers were estimated based on the calculated values of the statistical sums.

The infrared (400–4000 cm −1 ) spectra have been recorded in the crystalline state and in the melt for hexakis(4- N ′-dichloro(thio)phosphonyl)- N ′-methyl-diazobenzene)cyclotriphosphazene (G c1 ) which models the structure of dendrimer built from cyclotriphosphazene core. An X-ray diffraction study of G c1 was undertaken for the first time in order to understand why it is possible to obtain phosphorus dendrimers of high generations starting from cyclotriphosphazene core. Besides triphosphazene cycle constituting the core, G c1 possess also six C 6 H 4 CH N N(CH 3 ) P arms and terminal P Cl groups. The structural optimization and normal mode analysis are performed for G c1 molecule on the basis of the density functional theory (DFT). It is found that G c1 built from cyclotriphozphazene core has a concave lens structure. The G c1 molecules exist in a single stable conformation with planar O C 6 H 4 CH N N(CH 3 ) P fragments and slightly non-planar cyclotriphosphazene core. All these observations suggest that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied molecule.

Charged N,N-disubstituted hydrazine phosphorus-containing dendrimers are deposited either as alternate all-dendrimers multilayers or alternating with linear polymers on 3-mercaptopropionic acid or 3-aminopropyldimethylethoxysilane coated surfaces via electrostatic layer-by-layer self-assembly. The behavior of the film formation is investigated by surface plasmon resonance spectroscopy and ellipsometry. Fetal cortical rat neurons were cultured on the dendrimer films in order to investigate the influence of the surface charge of the outermost layer on their adhesion and maturation. It was found that neurons attached preferentially and matured slightly faster on film surfaces terminated with positively charged dendrimers than on negatively charged surfaces.

Inhibition of fibril assembly is a potential therapeutic strategy in prion diseases. The effect of cationic phosphorous dendrimers on the aggregation process of the prion peptide PrP 185-208 was studied using a spectrofluorometric assay with thioflavin T (ThT) and Fourier transformed infrared spectroscopy in order to monitor the kinetics of the process and the changes in the peptide secondary structure. The results show that phosphorous dendrimers are able to clearly interfere with PrP 185-208 aggregation process by both slowing down the formation of aggregates (by causing a decrease of the nucleation rate) and by lowering the final amount of amyloid fibrils, a common hallmark of conformational diseases. The dendrimers effect on the aggregation process would imply their interaction with peptide monomers and oligomers during the nucleation phase.

Staudinger reactions between triphenylphosphine and variously functionalized thiophosphorylazides afford compounds possessing one P N P S linkage. The X-ray diffraction structure of one functionalized azide and of a compound possessing a P N P S linkage are given. Alkylation of sulfur with methyltriflate, followed by desulfurization using a nucleophilic phosphine (P(NMe 2 ) 3 ) lead to a phosphazene connected to a tricoordinated phosphorus atom, able to undergo a Staudinger reaction with another thiophosphorylazide, to afford a P N P N P S linkage. Alkylation on sulfur allows to demonstrate by 31 P NMR a delocalization of the positive charge along the inorganic oligophosphazene linkage.

The FTIR spectra of seven generations of phosphorus dendrimers built from cyclotriphosphazene core with terminal phenoxy groups and theirs all-D isotope species have been recorded and analyzed. Their spectral pattern is determined by the ratio T / R ( T , the number of terminal groups, R , the number of repeating units). This ratio trends to r − 1 ( r , branching functionality of repeating unit), and becomes constant, when the generation number is higher than 3–5. Experimental IR spectra of generations higher than four are very close similar, according theoretical approach. The dependence of band full width at half height in the IR spectra on generation number is established. The influence of the encirclement on the band frequencies and intensity was studied and due to the predictable, controlled and reproducible structure of dendrimers the information usually inaccessible was obtained. Bands assigned to the core, repeated units and terminal groups of dendrimers were separated by the differential spectroscopy method. From the differential IR spectra of dendrimers it follows that for the generations higher than four, the steric congestion disturbs the conformations of the terminal groups. The rather rigid repeated units with little conformational flexibility define the perfect microstructure of phosphorus-containing dendrimers up to six generation. FTIR spectroscopy provides the unique detailed information about the structure of technologically relevant materials, which could not be obtained before with any other technique.

Dendrons possessing one activated vinyl group at the core and several chlorine atoms at the end of the branches are used as starting materials to study the possibility to react independently the surface functions and the core function. In particular, the most powerful sequence of reactions for decorating them by organometallic complexes as end groups and amine or alcohol at the core has been determined. In the first step, phenol phosphines are grafted as end groups of the dendrons, and they can be used for the complexation of metals. However, these phosphines must be kept free when amines are used to react with the vinyl core in the next step. Depending on the type of phosphine end groups and on the type of function of the core (amine or alcohol), the complexation of ruthenium ([RuCl 2 ( p -cymene)] 2 ) and rhodium ([RhCl(COD)] 2 ) derivatives by the phosphine end groups can occur without side reaction at the core.

The FT-Raman and FTIR spectra of 12 generations of phosphorus-containing dendrimers: Download : Download full-size image with terminal aldehyde and P Cl groups have been recorded and analyzed. Their spectral pattern is determined by the ratio T/R (T, the number of terminal groups; R, the number of repeating units). The influence of the encirclement on the band frequencies and intensity was studied and due to the predictable, controlled and reproducible structure of dendrimers the information usually inaccessible was obtained. Bands assigned to the core, repeated units and terminal groups of dendrimers were separated by the differential spectroscopy method. The strong band at 1600 cm−1 show marked changes of optical density in dependence of the aldehyde ( CH O) or azomethyne ( CH N ) substitution in aromatic ring. From the differential IR and Raman spectra of dendrimers it follows that for the generations higher than 6, the steric congestion disturbs the conformations of the terminal groups. The rather rigid repeated units with little conformational flexibility define the perfect microstructure of phosphorus-containing dendrimers up to 11 generation. FT-Raman and FTIR spectroscopy provides the unique detailed information about the structure of technologically relevant materials, which could not be obtained before with any other technique.

FT-IR spectra of phosphorus dendron G(1v) generation with terminal P-Cl groups have been recorded. Density functional theory is used for analyzing the properties of each structural part (core, branches, surface). It is found that the repeating branching units of G(1v) exist in a single stable conformation with planar -O-C(6)H(4)-CH=N-N(CH(3))-P fragments. DFT results for the structure of G(1v) are in good agreement with recent X-ray diffraction measurements. A complete vibrational assignment is proposed for different parts of G(1v). The global and local reactivity descriptors have been used to characterize the reactivity pattern of the core function and terminal group. Our study reveals that the most reactive site of G(1v) is the core function and =CH(2) side of vinyl group is preferred for nucleophilic attack. In the dendrimer G(1) the most reactive are the terminal groups. IR spectroscopy combined with ab initio DFT computation provides unique detailed information about the structure and reactivity of the technologically relevant materials, which could not be obtained before with any other technique.

Chiral ferrocenyl phosphine-thioether ligands have been covalently bound on the periphery of 4 phosphorus dendrimers (generations 1–4) having a cyclotriphosphazene core and on one model compound. These new dendrimers proved to be efficient ligands for the palladium-catalyzed asymmetric allylic substitution reaction (ee up to 93%).

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.

The infrared (150–3500 cm −1 ) spectra have been recorded for hexaphenoxycyclotriphosphazene [NP(OPh) 2 ] 3 and all-D isotope specie. These compounds include a cyclotriphosphazene core and terminal phenoxy groups of elementoorganic dendrimers. The structural optimization and normal mode analysis are performed for elementoorganic dendrimer on the basis of the ab initio density functional theory. It is found that the dendrimer exists in a single stable conformation with slightly non-planar cyclotriphosphazene core. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimers. The softness of sulphur atom in the thiophosphoryl core to nucleophilic attack is higher than the softness of the atoms of the cyclotriphosphazene core. The reactivity of the core is less than that of terminal groups.

FT-IR spectra of the phosphorus-containing dendron G′0v generation with terminal aldehyde groups have been recorded. The structural optimization and normal mode analysis are performed for the G′0v on the basis of the ab initio density functional theory. This calculations gave vibrational frequencies and infrared intensities for the t,g,g- and t,-g,g-conformers of the G′0v. The t,-g,g-conformer is 0.71 kcal/mol less stable compared to t,g,g-conformer. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the dendron. The influence of encirclement on band frequencies and intensity is studied and the information usually inaccessible is obtained. The global and local reactivity descriptors have been used to characterize the reactivity pattern of the core function and terminal groups. Our study reveals that the most reactive site in the dendron is the core function and the CH2 side of the vinyl group is preferred for nucleophilic attack. In the dendrimer the most reactive are the terminal groups.

The Raman and infrared spectra of the first generation of the phosphorus-containing dendrimer with terminal aldehyde groups have been recorded. The structural optimization and normal mode analysis are performed for phosphorus-containing dendrimer on the basis of the ab initio density functional theory. This calculations gave vibrational frequencies and infrared intensities for the t,g,g- and t,-g,g-conformers of the terminal groups. The t,g,g-conformer is 0.34 kcal/mol less stable compared to t,-g,g-conformer. It is found that the repeated units of dendrimer exists in a single stable conformation with planar O C6H4 CH N N(CH3) P fragments. All these observations suggest that steric congestion does not disturb the construction of dendrimers even for the highest generations, and that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimer. Our study reveals that in the G 1 ′ and G1 dendrimers the most reactive are the terminal groups. IR spectroscopy combined with ab initio DFT computation provides unique detailed information about the structure of the technologically relevant materials, which could not be obtained before with any other technique.

The infrared (150–3500 cm −1 ) spectra have been recorded for tris(4- N ′-dichloro(thio)phosphonyl)-( N ′-methyl-diazobenzene)monothiophosphate. This compound includes structural parts of elementoorganic dendrimers: a core, repeated units and terminal P–Cl groups. The structural optimization and normal mode analysis are performed for elementoorganic dendrimer on the basis of the ab initio density functional theory. It is found that the dendrimer exists in a single stable conformation with planar –O–C 6 H 4 –CH N–N(CH 3 )–P fragments. All these observations suggest that steric congestion does not disturb the construction of dendrimers even for the highest generations, and that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimer. IR spectroscopy combined with ab initio DFT computation provides unique detailed information about the structure of the technologically relevant materials, which could not be obtained before with any other technique.

A new class of Salpen analogues based on phosphorus derivatives where the classical alkylene backbone has been replaced by a N–P–N linkage is described. Such linkage both affords a very good stability in water and an additional (fifth) potentially complexing site. The classical ortho-OH groups have been also replaced by various ortho-substituents, including diphenylphosphino groups. The synthesis of these compounds is easy and their structure can be varied at will at several levels. Several ways of synthesis can be used to combine the various fragments constituting these Salpen analogues. The structure of one of these fragments, an azide, was determined by X-ray crystallography. A preliminary study of the complexation ability of some of these new ligands was carried out with groups 10 (Ni) and 11 (Au) elements. Depending on the type of substituents and the type of metals used, these compounds can act as mono-, or tetra-dentate ligands.

The Raman (10–3500 cm −1 ) and infrared (150–3500 cm −1 ) spectra have been recorded for tris(4-oxibenzaldehyde)thiophosphate. This compound includes structural parts of elementoorganic dendrimers: a core and terminal aldehyde groups. The structural optimization and normal mode analysis are performed for elementoorganic dendrimer on the basis of the ab initio density functional theory. It is found that the dendrimer exist in a single stable conformation with planar C 6 H 4 CH O fragments. Our calculations show that conformer with one trans and two gauche 4-oxibenzaldehyde groups is realized. All these observations suggest that steric congestion does not disturb the construction of dendrimers even for the highest generations, and that terminal groups are readily available for further reactions. Relying on DFT calculations a complete vibrational assignment is proposed for different parts of the studied dendrimers.

Dendrimers pertain both to the molecular chemistry world for their step by step controlled syntheses, and to the polymer world because of their repetitive structure made of monomers; thus they benefit from analytical techniques from both worlds. This review is a survey of the main analytical techniques used for the characterization of the chemical composition, the morphology, the shape, and the homogeneity of dendrimers. It includes NMR, IR, Raman, UV-Visible, fluorescence, circular dichroism, X-ray diffraction, mass spectrometry, SAXS, SANS, Laser Light Scattering, microscopy, SEC, EPR, electrochemistry, electrophoresis, intrinsic viscosity, DSC, and dielectric spectroscopy.

This review concerns metallic groups linked to the internal structure (core or branches) of phosphorus-containing dendrimers that are dendrimers possessing one phosphorus at each branching point. The synthetic aspect will be described first, ranked depending on the precise location of the metal: either at the core, or throughout the structure, or at one or several specific layers (layer-block type dendrimers), or in selected branches (segment-block type dendrimers). The second part concerns the properties of these metallo-phosphorus dendrimers, with emphasis on the information afforded by the metallic centers about the internal structure, and on the influence of the “burying” of a function inside a dendrimer on the properties of this function. The last part concerns the applications of some of these metallodendrimers in catalysis.

The synthesis of a third generation phosphorus-containing dendrimer possessing 24 chiral iminophosphine end groups derived from (2S)-2-amino-1-(diphenylphosphinyl)-3-methylbutane is described. In situ complexation of this dendrimer by [Pd(η3-C3H5)Cl]2 affords a catalyst, which is used in asymmetric allylic alkylations of rac-(E)-diphenyl-2-propenyl acetate and pivalate. The percentage of conversion, the yield of isolated 2-(1,3-diphenylallyl)-malonic acid dimethyl ester, and its enantiomeric excess have been measured in each case, and were found to be good to very good (ee from 90% to 95%). Furthermore, the dendritic catalyst can be recovered and reused at least two times, with almost the same efficiency.

In most cases, the water solubility of phosphorus-containing dendrimers is mainly due to the presence of hydrophilic end groups, which bear either positive or negative charges. In the first part of this paper, several methods of synthesis and functionalization of phosphorus dendrimers are described leading to the grafting either of ammonium groups or carboxylate groups, which ensure the water-solubility. The structural conflict between the hydrophobic interior and the hydrophilic exterior of these dendrimers leads to special properties, which are emphasized in a second part. For instance, some of them behave like nanometric sponges toward lipophilic substances; whereas, others form supramolecular arrangements leading to vesicles or hydrogels. Some of these dendrimers also possess interesting biological properties and can be used as in vitro DNA transfecting agents or in vivo anti-prion agents.

The FT-Raman (10–3500 cm−1) spectra of ten generations of the elementoorganic dendrimers have been recorded and analyzed for the first time. Their spectral pattern is determined by the ratio Nt/Nr (Nt—number of terminal groups, Nr—number of repeating units). This ratio trends to mr−1 (mr—branching functionality of repeating unit), and becomes constant, when the generation number is higher than 3–5. Experimental Raman spectra of generations higher than 4 are very close similar, according theoretical approach. The dependence of line full width at half height in Raman spectra on generation number is established. The low frequency Raman spectra in R(ν) representation are used to investigate the librations of terminal groups. The possibility appears to separate the lines assigned to the core, repeated units and terminal groups of dendrimers by difference spectroscopy method. From the difference Raman spectra of dendrimers it follows that for the generations higher than six steric congestion disturb the conformations of terminal groups. FT-Raman spectroscopy provides unique detailed information about the structure of the technologically relevant materials, which could not be obtained before with any other technique.

The selective reaction of amines and hydrazides with only one Cl on each P(S)Cl 2 or P(O)Cl 2 end group of phosphorus dendrimers, followed by the grafting of hydroxybenzaldehyde on the remaining P–Cl functions, and the subsequent growing of the dendrimer from the aldehyde is described. Allyl and pyrene derivatives have been grafted in this way inside the dendrimers during their growing. This constitutes a new way for the internal functionalization of dendrimers.

Phosphoryl azides are known as azide-transfer agents in organic chemistry; such behavior denotes the pseudo-halogen character of the azide group when linked to a tetracoordinated phosphorus atom, but it was considered up to now only for the functionalization of organic substrates by N3. We show in this paper that the azide can also be considered as a good leaving group, which facilitates the functionalization of the phosphorus atom which bore it. This reaction is first demonstrated on a small thiophosphoryl azide, then applied to the functionalization of more complex macromolecules, i.e. macrocycles incorporating in their structure thiophosphoryl azido groups.

Various methods of synthesis of phosphorus dendrimers are presented, in particular a fast method which allows creating each generation in only one step, while multiplying by 5 the number of end-groups. These methods of synthesis can easily be modified to place selectively on the surface, inside, within the branches or at the core, functional groups chosen according to the properties or the applications which they can bring. In many cases, the size of the dendrimer (its generation) has an influence on these properties. Various applications in the fields of catalysis, materials, and biology are presented. To cite this article: Anne-Marie Caminade et al., C. R. Chimie 6 (2003).

International audience; Three new series of phosphorus-containing dendrimers are described. Their solubility depends on the type of end groups they bear. Perfluoroalkyl chains give dendrimers soluble in chlorofluorocarbons, whereas guanidinium and pyridinium derivatives give watersoluble compounds. The thermal stability of these compounds, as well as of 19 other dendrimers of various generations, having various cores, or various end groups, or branching points is studied. The main feature of this study is that the internal structure of these dendrimers is thermally stable at least up to 3768C. The number of the generation has practically no influence, whereas the principal criterion influencing the thermal stability is the type of end groups. The water-soluble cationic dendrimers are the least stable, but even those are stable up to 2258C. For most of these dendrimers, an important percentage of mass (around 50%) is retained even at a temperature as high as 10008C. In the best case, up to 70% of the initial mass is retained at 10008C.