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Abstract: Dendrimers are promising polymers for biomedical applications; however, most dendrimer formulations have failed to move from laboratory science to upscaled products for preclinical testing or GMP production. This publications [...]

The use of a new class of high-molecular-weight substances, dendritic polymers (dendrimers and hyperbranched polymers), as components of chromatographic and electrophoretic systems is discussed; the effect of their introduction into a background electrolyte or an eluent on the separation efficiency and selectivity of organic compounds of different classes is considered. Keywords: dendrimers, hyperbranched polymers, modifiers, capillary electrophoresis, chromatography. DOI: 10.1134/S1061934812030069, In recent years, there has been an increased interest in dendrimers and hyperbranched polymers in connection with revealing the physical and chemical properties opening the possibility of their use in [...]

The guest-host interactions of poly(amidoamine) (PAMAM) dendrimers and porous silica surfaces were investigated by near-infrared (NIR) diffuse reflection spectroscopy. G0-G7 of amine-terminated PAMAM (PAMAM-N[H.sub.2]) dendrimers were analyzed comprising early, mid, and late generations. For early stages, the adsorption process of the partly protonated dendrimers to the negatively charged silica surface strongly depends on the size/shape characteristics of the guest (PAMAM-N[H.sub.2] dendrimers) and host (porous silica) materials. G0-G4 (15-45 [Angstrom]) show smaller particle sizes than the pore diameter of the silica (60 [Angstrom]) and thus have access to the interior surface of the host material. For mid and later stages (G5-G7; 54-81 [Angstrom]) only low amounts of the dendrimers adsorb to the silica surface due to the inaccessibility to the interior surface. The loading capacity of the silica material with adsorbed PAMAM-N[H.sub.2] was evaluated by means of capillary zone electrophoresis (CZE), whereas deviations from the theoretical to the effective particle size and molecular weight (MW) was determined by gas-phase electrophoretic mobility molecular analysis (GEMMA) and matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometry (MALDI-lin TOF-MS). Deviations from the theoretical to the actual values showed a maximum of 13.8% and 28.0% for the particle size and MW, respectively. The NIR absorption spectra show a distinct band at 4932 [cm.sup.-1] ([v.sub.sym] (NH) + amide II) due to the adsorbed dendrimers. It was found that the absorbance tends to increase with decreasing generation number. On this basis multivariate calibration was performed with the theoretical data and the data obtained by GEMMA and MALDI-lin TOF-MS. All in all, the calculated partial least-squares regression (PLSR) model containing the GEMMA/MALDI-lin TOF-MS reference values showed better results than the models exclusively calculated from the theoretical values. This indicates that the theoretical values do not imply the structural imperfections arising during the synthesis that may be present in the PAMAM-N[H.sub.2] dendrimers.

A dynamic 'two-site' model was formulated and tested for simulating the elution histories of copper ([Cu.sup.2+]) and lead ([Pb.sup.2+]) from a contaminated soil treated by poly(amidoamine) dendrimers. In the model, the metal sorption sites of the soil were divided into two compartments: one with a fast desorption rate and the other with a slow desorption rate. The model was tested for simulating and predicting [Cu.sup.2+] and [Pb.sup.2+] elution histories obtained from column experiments. Compared to the classical 'one-site' model and the modified 'gamma distribution' model, the 'two-site' model not only provides much improved power for simulating the observed metal elution data, but also can more accurately predict the metal elution histories under various experimental conditions including initial metal concentration in soil, dendrimer concentration, and pH. DOI: 10.1061/(ASCE)0733-9372(2008)134:4(238) CE Database subject headings: Abatement and removal; Models; Remedial action; Extraction procedures; Heavy metals; Soil pollution; Soil treatment.

The fabrication of dendrons [G.sub.n]-Cl and [G.sub.n]-NH (n = 2-4) and novel dendrimers [G.sub.n]-N N-[G.sub.n] (n = 2-4) based on triazine and piperazine units is reported. The compounds are transparent and have good thermal stability.

The article studies the singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin dendrimers. The energy transfer efficiency of these dendrimers can be improved by extending the chain that connects the chromophores to the dendrimeric backbone.

The design and synthesis of A[B.sub.4] and A[B.sub.5] dendritic building blocks with complex architecture are described. They has self-assembled into spherical dendrimers with a less densely packed center and the long-range helical structures are established by applying the helical diffraction theory of the analysis of X-ray patterns obtained from oriented fibers of supramolecular dendrimers.

The mechanism of formation of the CB[n] family of macrocycles and the mechanism of the conversion of iCB[6] to CB[6] under acidic conditions are described. It is shown that iCB[6] and iCB[7] are kinetically controlled intermediates in the formation of CB[n].

Three polyphenylene dendrimers which were studied by molecular modeling techniques to define the notion of shape persistence associated with such molecules is reported.

The synthesis and characterization of a new class of highly fluorescent and stable carbazole-based dendrimers that contain the ethynylbenzene and diethynylbenzene cores are presented. The results have indicated the dendrimers potential use as blue-emitting materials in organic light-emitting diodes (OLEDs).

A study of the fluorescence properties of dendrimers (GN is the dendrimer generation number) comprising of four varying luminophores , terphenyl (T), dansyl(D), stilbenyl(S) and eosin (E) is presented. The various mechanisms of fluorescence depolarization observed in the analysis, depending on the photophysical properties of the fluorescent units and structures of the dendrimers, are discussed.

The largest chemically monodisperse molecules to date, up to 28nm at 271.6 kDa for the sixth generation is synthesized using the divergent polyphenylene dendrimer synthesis. Self-assembly is inextricably linked with the synthesis as well as analysis and gives hitherto access to tremendous 3D nanostructural control.

The developments in homogeneous nanosize Pd catalysts containing solubilized Pd nanoparticles, metalated dendrimers, and complexes with well-defined nanosized care reviewed. These homogeneous nanosize Pd catalysts realize efficient catalyst recycling, unique selectivity, suppression of metal aggregation, and remarkable enhancement of the catalytic activity.

A new synthetic strategy is described for the construction of boron-based macrocycles and dendrimers. The results have highlighted the importance of boron-based compounds in supramolecular chemistry.

Various steps of preparation process of Pt/[gamma]- [AI.sub.2][O.sub.3] using hydroxyl-terminated generation four (G4OH) PAMAM dendrimers as the templating agents are monitored by extended X-ray adsorption fine structure (EXAFS) spectroscopy. The results indicate that the hydrolysis of two different platinum precursors, namely [H.sub.2]Pt[CI.sub.6] and [K.sub.2]Pt[CI.sub.4] leads to the formation of [Pt[Cl.sub.3][[H.sub.2]O.sub.3]].sup.+ and [Pt[Cl.sub.2][[H.sub.2]O.sub.2]] species respectively.

The binding capacity of rigid ruthenium metallodendrimers to single-walled carbon nanotubes (SWNTs) is studied with the ultraviolet (UV)-vis and atomic absorption spectroscopy. The statistical analysis of the atomic force microscopy (AFM) images has shown that the morphology of the functionalized ends is consistent with the nanotubes binding to one of the endo- or exoreceptors around the dendrimer.

Materials multifunctionality for optical sensing of adsorbates has obvious advantages--in addition to the potential for greater sensitivity, the different length scales associated with a variety of optical phenomena allow a greater variety of adsorption characteristics to be examined. Here, we show that ultrathin (~100 nm) nanoporous gold membranes possess features of both planar metal films that exhibit propagating SPR excitations and nanofeatured metals that exhibit localized SPR excitations. This is the first report of such multifunctionality in an optically active metal. We give illustrative examples of using this material to probe biorecognition reactions and to probe the structure evolution of a layer-by-layer deposition of charged dendrimers. Our results are consistent with the very different lengths of the tail of the evanescent field decays associated with each of these plasmon excitation modes.

The synthesis of mesomorphic bisadducts of [60]fullerene was carried out with the use of a second-generation cyanobiphenyl-based dendrimer as a liquid-crystalline promoter. The findings suggest that the supramolecular organization of the bisadducts is governed by the nature and structure of the mesogenic groups and dendritic core.

The formation of dendronized polymers was demonstrated by acid-base reactions, which showed that the system could be switched to rigid dendronized polymers and flexible polymers reversibly. The investigations revealed good stability even after many cycles of the acid-base switching processes.

A photoactive layer, consisting of electron-donating zinc prophyrin and electron-accepting fullerene arrays on the dendrimer surface is constructed using [DP.sub.m] 9m= 6, 12, and 24) and Py2[F.sub.n] (n= 1-3) by means of a multivalent surface ligation of dendritic macromolecules. Upon increment of the numbers of these donor and acceptor units, the electron transfer reaction was remarkably facilitated, while the recombination of the resulting charge-separated state remained virtually intact.

The synthesis of 'designer' dendrimers and dendrons with sulfonlmide units at every branching point is reported. Two models branched oligosulfonimides are characterized in the solid state by single-crystal X-ray analysis and the reaction selectivities and conformation of sulfonimide branching points are rationalized by DFT calculations.

An attempt is made to examine the divergent growth of surface-initiated dendritic nanostructures on gold surfaces in a highly controlled, stepwise manner using metal-organic coordination as the binding motif. It is revealed the surface initiation sites for dendrimer growth were obtained by the formation of a mixed monolayer comprising isolated bis-hydroxamate disulfide anchor ligands and octanethiol (OT) at very low anchor/OT ratios.

The preparation and characterization of nitric oxide (NO) releasing dendrimer conjugates from primary and secondary amine functionalized dendrimers are reported. It is observed that the total NO released from secondary amine conjugates is significantly greater than from the primary amine parent dendrimers due to the enhanced stability of secondary amine diazeniumdiolates.

The complete determination of an early-generation dendrimeric material was carried out directly from powder X-ray diffraction data using the direct space genetic algorithm technique for structure solution followed by Rietveld refinement. The success of this new technique paves the way for the future application of this approach to enable complete structure determination of other dendritic materials that cannot be prepared as single crystal samples suitable for single crystal X-ray diffraction studies.

A synthetic and mechanistic study of 32 different dendrimer mutants in a certain series is reported which establishes the robustness of the peptide dendrimer synthesis and catalytic properties observed. An automated parallel synthesis protocol is developed for facilitating the synthesis of analogues.

Single-walled carbon nanotubes (SNWTs) can be grown microwave plasma-enhanced chemical vapor deposition (PECVD) by using dendrimer-templated and stabilized, nearly monodispersed [Fe.sub.2][O.sub.3] nanoparticles. The results can be used to promote the use of exposed Fe nanoparticles supported on different substrates for the growth of high-quality SWNTs by PECVD.

A description is provided about the convergent synthesis of three generations of carbosilane dendrimeric carbodiimides. A study was conducted on the extent of site isolation effect of the dendrimers with dilution experiments monitored by FT-IR spectroscopy on the corresponding dendrimeric ureas.

Hexasubstitution of apical triflate ligands in the octahedral clusters [M](sub 2) [Mo(sub 6X(sub 8)(CF(sub 3)SO(sub 3)(sub 6)] (M=n-Bu(sub 4)N or Cs, X=Br or I) and monosubstitution in [n-Bu(sub 4)N](sub 2)Mo(sub 6)Br(sub 13)(CF(sub 3)SO (sub 3)] was carried out in tetrahydrofuran with simple pyridines and then extended to organometallic pyridines. The organometallic pyridines yielded cluster-cored stars, and dendronic polyallyl and polyferrocenylpyridiens yielded cluster-coated polyallyl and polyferrocenyl dendrimers and dendrons.

The spectroscopic and electrochemical behavior of the symmetric and unsymmetric first-, second-, and third-generation dendrimers (Dn)(sub 2)B(super 2+) (symmetric dendrimers) and DnB(super 2+) (unsymmetric dendrimers) (n = 1,2,3) and their host-guest complexes with tweezer T is investigated. The host-guest complexes between the tweezer and the dendrimers are stabilized by electron donor-acceptor interactions and can be reversibly assembled or disassembled by electrochemical stimulation.

The singlet-singlet annihilation within the series of Zn-porphyrin dendrimers by means of intensity dependent transient absorption experiments is studied. Analysis showed that sequential annihilation occurs within subunits up to four Zn-porphyrins in the dendrimers, and a full characterization of the transient absorption kinetics of the monomer over a spectral range from 450 to 730 nm is reported.

A study to quantify loadings in heterogeneously functionalized dendrimers using the mass spectrometry and EPR spectroscopy was conducted. The results indicated that the coupling reactions were shown to go to completion for all the reactions studied, independent of the sequence of the reaction under the employed conditions.

The synthesis of a family of phosphorus dendrimers built from an octasubstituted metal-free phthalocyanine core is described up to generation 5. UV-visible spectra show both a hyperchromic and bathochromic effect on the Q-bands with increasing generation, indicating that the chromophore is more isolated and that the dendritic shell mimics a highly polar solvent.

The photochemical properties of a series of newly synthesized dendrimers, having a 2-(2'-hydroxyphenyl)-benzoxazole (HBO) core, are studied in benzene. The results of the dendrimer effect on the fluorescence quantum yield of the excited-state intermediate are the evidence of an efficiency increase with relation to the deactivation process of (E)-keto form (super 1)K(sub E) by isomerization to give the ground-state (Z)-keto form (super 1)K(sub z).

The synthesis of a block codendrimer (g3-PBE-b-gr-PMDC), composed of a third-generation poly(benzyl ether) (PBE) monodendron and an aliphatic polyether (PMDC) monodendron is reported. The effect of molecular architecture on the formation of the interdigitated layers and vesicles is studied.

The photophysical properties of an organic dye (Congo Red) incorporated within the internal cavities of a dendrimer (type polypropylenimine of fifth-generation modified with a dense shell of amino acids) is investigated. It is observed that the emission frequencies of Congo Red, on modulation by electronic confinement effect, can be red shifted with respect to their emission solution, and the magnitude of this shifting can be modulated under appropriate experimental conditions.

A study investigated the synthesis and spectroscopic properties of two second generation (G2) dendrons with site-specific incorporated phenyl pyrene derivatives as solvatochromic fluorescent probes. The incorporated probes can be selectively photoexcited and show solvatochromic shifts that are of the same magnitude as for the free probes in a homogenous solvent environment.

Luminescent and redox-active prophyrin-based dendrimers of first and second generation are synthesized, and their absorption spectra, photophysical properties, and oxidation behavior is investigated. All the dendrimers contain a porphyrin core and carbazole-based chromophores as braches.

Electrochemical, spectroscopic, and mass spectrometric (MS) methods were used to probe the interaction (complexation) of silver ions and zerovalent silver species with polyamidoamine generation 1 amine-terminated (PAMA-MG1N[H.sub.2]) and generation 2 hydroxy-terminated (PAMA-MG2OH) dendrimers (DDMs). Stability constants ([K.sup.+.sub.q]) and stoichiometries (q) (i.e., the number of silver ions complexed per DDM molecule) were determined from the voltammetric data, that is, shifts in potential and changes in peak or limiting current with addition of DDM. When the mole ratio of DDM to [Ag.sup.+] is [greater than or equal to] 1, [Ag.sup.+] binds with PAMAMG2OH to form a dominant 1:1 complex with a [K.sup.+.sub.1] value of 1.1 x [10.sup.7] [M.sup.-1]. Under similar conditions, [Ag.sup.+] binds with PAMAMG1N[H.sub.2], yielding a 1:1 complex with [K.sup.+.sub.1] = 4 x [10.sup.9] [M.sup.-1], which is consistent with the finding of the MS experiments. When the mole ratio is

Synthesis and studies of poly(alkyl aryl ether) dendrimers, possessing carboxylic acid functionalities at their peripheries, are reported. The photochemical studies of carboxylic acid functionalized dendrimers are compared to that of hydroxyl group terminated poly(alkyl aryl ether) dendrimers.

Silole-core dendrimers having benzyl-ether-type dendron units in the periphery are readily synthesized by the Ni-catalyzed reaction of benzyloxy-substituted diphenylacetylenes with 1,1,2,2-tetramethyldisilane. Key words: silole, dendrimer, nickel-catalyzed reaction, convergent synthesis. La synthese de dendrimeres a coeur de silole possedant des dendrones de type ether benzylique a la peripherie peut etre realisee facilement en faisant appel a la reaction du 1,1,2,2-tetramethyldisilane avec des diphenylacetylenes substitues par un groupe benzyloxy, catalysee par du nickel. Mots cles : silole, dendrimere, reaction catalysee par le nickel, synthese convergente. [Traduit par la Redaction]

The synthesis, characterization and applications of dendrimer-encapsulated nanoparticles (DENs) are discussed. The materials are synthesized by a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse particles having dimensions of less than 3nm.

Nonconjugated dendrimers, which are capable of funneling energy from the periphery to the core followed by a charge-transfer process from the core to the periphery, are synthesized. The energy transfer occurs on a picosecond time scale, while the charge transfer process occurs on a nanosecond time scale.

Disorder-induced symmetry breaking is studied in a model dendrimer that consists of three arms arranged with C3 symmetry. The symmetry breaking of the dendrimer is modeled as a function of its structural disorder.

Bimetallic dendrimer-stabilized nanoparticles (DSNs) are used to prepare supported Pt-Au catalysts within the bulk miscibility gap for this binary system. The transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and infrared spectroscopy of adsorbed CO show that this preparation route results in NPs in which the two metals are intimately mixed and that the majority of the bimetallic NPs are smaller than 3 nm.

A series of [G1] to [G3]-oligo(dibenzylsulfide) dendrimers containing up to 21 interior dibenzylsulfide moieties is prepared as starting materials toward the syntheses of two new series of oligo(dibenzylsulfone) and oligo(phnylenevinylene) dendrimers using two different dendrimer-to-dendrimer conversion strategies. The findings demonstrate successful conversions of up to 21 interior dibenzylsulfide moieties to the corresponding dibenzyl sulfone groups.

The synthesis of azobenzene-functionalized multi-armed unimolecular initiators or "unimers" that can be polymerized using styrene or styrenic derivatives via TEMPO (2,2,6,6-tetramethylpiperidenyl-1-oxyl) mediated stable free radical polymerization (SFRP) is described. The unimers are composed of an azobenzene-functionalized core and a TEMPO-modified unit. Homopolymers and copolymers of styrene and acetoxystyrene were synthesized using the mono-and trifunctionalized unimers as initiators under bulk conditions with average molecular weights and polydispersities reported. The studies lay the groundwork for further investigations involving SFRP towards building a light harvesting system by introducing chromophores onto the polymer chains for capturing light and thence transferring it to the azobenzene core. Key words: azo-functionalized unimolecular initiator, stable free radical polymerization, starburst dendrimer.

The synthesis of the trifunctionalized TEMPO-modified unimolecular initiators, unimers I, II, and III is described. Unimer I was prepared via an [S.sub.N]2 type Williamson ether coupling of 1,3,5-tris(iodomethyl)benzene with a TEMPO-containing ethylbenzene hydroxy derivative. The synthesis of unimer II, however, was accomplished through [S.sub.N]1 reaction of 1,3,5-tris(bromomethyl)benzene with the hydroxy-ethylbenzene TEMPO derivative in the presence of silver triflate. Synthesis of unimer III started from phloroglucinol and an [S.sub.N]Ar reaction with 1-fluoro-4-nitrobenzene, followed by reduction to the amino compound and Schiff base formation with the TEMPO-derivatized aromatic aldehyde. Stable tree radical polymerisation (SFRP) of styrene and acetoxystyrene with unimer I are also described with molecular weights and polydispersities reported. It is concluded that the SFRP of styrene with a triradical initiator meets the requirements of a living system. Key words: stable free radical polymerisation, starburst dendrimer, multi-armed unimolecular initiators.

A small library of dendrimers is prepared from a common precursor that is available in 5 g scale in five linear steps at 56% overall yield. The PEGylated dendrimer is evaluated for acute toxicity in vivo and the findings indicate that cationic dendrimers are found to be more cytotoxic and hemolytic potential and cytotoxixity.