Single‐Crystalline Optical Microcavities from Luminescent Dendrimers

Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First‐, second‐, and third‐generation carbazole (Cz) dendrimers with a carbon‐bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1–3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2‐ and G3COPV2 align omnidirectionally. The dendrons work as light‐harvesting antennas that absorb non‐polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers.     

Single component transparent free‐standing films based on polyhedral octasilicate‐core dendrimers bearing carbazole terminal groups and their emission properties

9H‐carbazole‐9‐ethyl and 9H‐carbazole‐9‐hexyl‐terminated polyhedral octasilicate (OS)‐core dendrimers, denoted as OS‐C2‐Cz and OS‐C6‐Cz, respectively, were prepared by ring‐opening reaction and subsequent condensation of octakis(propenyl succinicanhydrido)polyhedral octasilicate (OS‐SA) with 9H‐carbazole‐9‐ethanol (Cz‐C2‐OH) and 9H‐carbazole‐9‐hexanol (Cz‐C6‐OH), respectively. Both the dendrimers formed optical transparent coating films. In particular, the coating film of OS‐C2‐Cz was easily peeled off from a substrate and formed a free‐standing film. The results of X‐ray diffraction and differential scanning calorimeter suggest that the films of OS‐C2‐Cz and OS‐C6‐Cz were amorphous. Thermogravimetric analysis of OS‐C2‐Cz and OS‐C6‐Cz showed 10 wt % weight losses at 374 and 383 °C, respectively. Photoluminescence property revealed that the carbazole group in OS‐C2‐Cz is prevented the excimer formation, while the carbazole group in OS‐C6‐Cz formed the excimer. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 628–633     

Synthesis of carbosilane dendritic wedges and their use for the construction of dendritic receptors

A divergent route for the synthesis of carbosilane wedges that contain either a bromine or amine as focal point has been developed. These new building blocks enable the construction of various core-functionalized carbosilane dendrimers. As a typical example carbosilane dendrimers up to the third generation containing a N,N',N'-1,3,5-benzenetricarboxamide core (G1-G3) have been synthesized. This new class of molecules has been studied as host molecules and they have been found to bind protected amino acids as guest molecules via hydrogen bonding interactions. A decrease in the association constants was observed for the higher generation dendritic hosts, which is attributed to the increased steric hindrance around the core where the binding site is located. The binding properties of the dendritic host molecules can be tuned by modifying the binding motif at the core of the carbosilane dendrimers. A higher association constant for N-CBZ-protected glutamic acid 1-methyl ester (5) was observed when the third generation N,N',N'-1,3,5-tris(L-alaninyl)benzenetricarboxamide core-functionalized carbosilane dendrimer (G3') was used as the host molecule compared to G3. Different association constants for the formation of the diastereomeric G3'.L-5(K=295 M(-1)) and G3'.(D-5)(2) (K=236 M(-1)) host-guest complexes were observed, pointing to a small enantioselective recognition effect. The difference between the association constants for the formation of the G3'.(L-5)(2) and G3'.(D-5)(2) host-guest complexes was much more pronounced, K=37 M(-1)versus K=10 M(-1), respectively.     

"Click" synthesis and properties of carborane-appended large dendrimers

Large dendrimers, noted G(n)-3(n+2)cage, containing 3(n+2) o-carborane cluster cages MeC(2)B(10)H(10) at their peripheries (n = number of generation noted G(n)) have been synthesized by Huisgen-type azide alkyne Cu(I)-catalyzed dipolar "click" cycloaddition reactions (CuAAC) between an o-carborane monomeric cluster containing an ethynyl group and arene-centered azido-terminated dendrimers G(n)-3(n+2)N(3) of generations 0, 1, and 2. Attempts to synthesize higher-generation dendrimers of this family yielded insoluble materials. The carborane dendrimers G(0)-9cage, G(1)-27cage, and G(2)-81cage have been characterized by (1)H, (13)C, (11)B NMR, elemental analysis, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectroscopy, and size exclusion chromatography (SEC) showing low polydispersities, dynamic light scattering (DLS) showing hydrodynamic diameters of 5.7 nm for the G(1)-27cage and the 12.9 nm for the G(2)-81cage. These dendrimers are extremely robust thermally, with 10% mass loss temperatures of 411 °C for the G(0)-9cage, 371 °C for the G(1)-27cage, and 392 °C for the G(2)-81cage. They all showed a strong absorption in the UV region peaking at 258 nm, whereas emission spectra of low intensities were observed between 280 and 480 nm.     

溶剂对聚酰胺-胺树形分子模板法原位制备CdS量子点的影响

为了研究非配位型溶剂对聚酰胺-胺(PAMAM)树形分子的模板法制备CdS量子点的影响, 分别以水、甲醇及二者的混合物( ∶ ＝2∶1)为溶剂, 以4.5代PAMAM树形分子为模板制备了CdS量子点. 结果表明, 相同条件下, 以甲醇为溶剂时制备的CdS量子点为单晶, 平均直径2.7 nm, 尺寸分布窄, 发光强度高; 以水为溶剂制备的CdS量子点为多晶, 平均直径为5.7 nm, 尺寸分布宽, 发光强度低; 在甲醇与水的混合溶剂中制备的CdS量子点为单晶和多晶共存, 平均直径为4.1 nm, 尺寸分布及发光强度都居中. 这主要是由于树形分子的模板作用不同造成的. 树形分子在甲醇中能充分伸展, 起到内模板作用; 树形分子与水之间由双氢键作用而产生交联, 不利于Cd^2＋与树形分子内部基团的配位, 主要起到外模板作用; 在甲醇与水的混合溶剂中, 树形分子则同时起到了内模板和外模板作用.     

Polycationic (mixed) core-shell dendrimers for binding and delivery of inorganic/organic substrates

The convergent synthesis of a series of polycationic aryl ether dendrimers has been accomplished by a convenient procedure involving quantitative quaternarization of aryl(poly)amine core molecules. The series has been expanded to the preparation of the first polycationic, mixed core-shell dendrimer. All these dendrimers consist of an apolar core with a peripheral ionic layer which is surrounded by a less polar layer of dendritic wedges. These cationic, macromolecular species have been investigated for their ability to form assemblies with (anionic) guest molecules. The results obtained from UV/Vis and NMR spectroscopies, and MALDI-TOF-MS demonstrate that all the cationic sites throughout the dendrimer core are involved in ion pair formation with anionic guests giving predefined guest/host ratios up to 24. The large NMR spectroscopic shifts of resonances correlated with the groupings located in the core of the dendrimers, together with the relaxation time data indicate that the anionic guests are associated with the cationic core of these dendrimers. The X-ray molecular structure of the octacationic, tetra-arylsilane model derivative [Si(C6H3[CH2NMe3](2)-3,5)4]8+. 8I- shows that the iodide counterions are primarily located near the polycationic sphere. The new polycationic dendrimers have been investigated for their catalytic phase-transfer behavior and substrate delivery over a nanofiltration membrane.     

Bipolar Heteroleptic Green Iridium Dendrimers Containing Oligocarbazole and Oxadiazole Dendrons for Bright and Efficient Nondoped Electrophosphorescent Devices

Bipolar heteroleptic green light‐emitting iridium (Ir) dendrimers G(OXD) and G(DOXD) have been designed and synthesized under mild conditions in high yields, in which the first C^N and second O^O ligands are functionalized with oligocarbazole‐ and oxadiazole‐based dendrons, respectively. To avoid affecting the optical properties of the emissive iridium core, all the functional moieties are attached to the ligands through a flexible spacer. Compared with the unipolar dendrimer G(acac ), dendrimers G(OXD) and G(DOXD) exhibit the close emission maxima of 511–512 nm and photoluminescence quantum yield of 0.39–0.40 in a solution of toluene. Moreover, on going from G(acac) to G(OXD) and G(DOXD) , we have found that the introduction of oxadiazole fragments decreases the lowest unoccupied molecular orbital (LUMO) energy levels to facilitate the electron injection and electron transporting, while their highest occupied molecular orbital (HOMO) energy levels remain unchanged. This means that, we can individually tune the HOMO and LUMO energy levels based on the heteroleptic structure to ensure the relative independence between the hole and electron in the emitting layer (EML), which is a favorable feature for bipolar optoelectronic materials. As a result, a bilayer nondoped electrophosphorescent device with G(DOXD) as the EML gives a maximum luminous efficiency of 25.5 cd A⁻¹ (η_ext: 7.4 %) and a brightness of 33 880 cd m⁻². In comparison to G(acac) (17.2 cd A⁻¹, 17 680 cd m⁻²), both the efficiency and brightness are improved by about 1.5 and 2 times, respectively. These state‐of‐the‐art performances indicate the potential of these bipolar heteroleptic iridium dendrimers as solution‐processible emitting materials for nondoped device applications.     

Synthesis and photophysical properties of poly-(phenylenevinylene) dendrimers with a ruthenium tris-bipyridine core

The photophysical processes have been investigated in first, second and third generation dendrimers with poly-(phenylenevinylene) branches and a ruthenium tris-bipyridine core, RuDn (n = 1–3). These dendrimers show very efficient forward singlet–singlet energy transfer from the branches to the ruthenium core upon UV irradiation, with efficiencies of 0.99 for RuD1 and 0.88 for RuD2 and RuD3 in CH₂Cl₂. The RuDn dendrimers show a bi-exponential emission decay in CH₂Cl₂, when excited with a 460 nm light with short lifetimes, however, the emission decay lifetimes become mono-exponential in 10% Triton X-100 aqueous solution (τ = 840 ns for RuD1, 890 ns for RuD2 and 1120 ns for RuD3).     

New metallodendrimers containing an octakis(diphenylphosphino)-functionalized silsesquioxane core and ruthenium(II)-based chromophores

A new class of surface-modified dendrimers has been prepared by reactions of 8 equiv of the terpyridine-functionalized polyether monodendrons with a polyhedral oligomeric silsesquioxane (POSS) core. Subsequent reactions of these spherically shaped organic dendrimers with Ru(II)-based precursors afford photo- and redox-active metallodendrimers. These new dendrimers have been characterized using a combination of mass spectral analysis (MALDI-TOF/MS, ESI/MS, and FAB/MS), nuclear magnetic resonance (1H, 13C, 29Si, and 31P(1H) NMR), photophysical analyses (electronic absorption, emission, excited-state lifetime, and quantum yield) and electrochemical measurement (cyclic voltammetry). Specifically, 31P(1H) NMR is used to monitor the completion of reactions and the purity of dendrimers and metallodendrimers. These new metallodendrimers exhibit large extinction coefficients that coincide with the number of peripheral Ru(II)-based chromophores. With the use of (-CH2-Ph-tpy)RuII(bpy)2 type of chromophores, all metallodendrimers are found emissive at room temperature, with lifetimes in the range of 605-890 ns. Photophysical data also indicate similar steady-state emission maxima and single-exponential decay kinetics for all metallodendrimers, and the observed overall quantum yields of the G1, G2, and G3 metallodendrimers are found to be 14, 20, and 7 times higher than that of the monomeric model complex (CH3-Ph-tpy)Ru(bpy)2(PF6)2. Electrochemical studies reveal the presence of surface-confined species, in addition to the ligand-centered and metal-centered redox processes.     

聚酰胺-胺型树枝状高分子水溶液的表面活性

树枝状化合物是一类三维的、高度有序的新型高分子.与传统高分子相比,这类化合物在合成时,可以在分子水平上严格控制,设计分子大小、形状、结构和功能基团,产物一般高度对称,单分散性好.因而具有广泛的潜在用途^[1,2].近年来,已引起广大化学工作者的重视.     

Preparation of Unconventional Dendrimers that Contain Rigid NH?Triazine Linkages and Peripheral tert‐Butyl Moieties for CO2‐Selective Adsorption

Three unconventional dendrimers that contained rigid NH? triazine linkages and peripheral tert‐butyl moieties were prepared by using a convergent approach and characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry, and elemental analysis. Based on a thermogravimetric analysis study, these dendrimers were observed to display thermal stability at about 300 °C. The NH? triazine moiety, which possessed protonated and proton‐free nitrogen sites (like the imidazole unit), displayed the capture of polarizable CO₂ molecules through hydrogen‐bond and/or dipole–quadrupole interactions. In addition, the adsorption of various amounts of CO₂ and N₂ at different pressures suggests that the dendritic pores, which arise from the stacking of the middle co‐planar and rim protuberant dendrimers, G _n ‐N～N‐G _n (n=1–3), either swell or shrink at high pressure, thus indicating that these dendrimers may have a breathing ability.     

Hetero type III-B rotaxane dendrimers

Type III-B rotaxane dendrimer is a member of the rotaxane dendrimer family, but it is defined as dendritic polyrotaxane, branched through rings. Such rotaxane dendrimers have been synthesized through versatile copper-catalyzed azide-alkyne cycloaddition reactions. In order to incorporate more functionalities into type III-B rotaxane dendrimers, three different potential functionalities—azobenzene toward light switch, daisy chain toward higher degree of contraction, and extension and cyclobis (paraquat-p-phenylene) (CBPQT) toward redox chemistry—were combined into the original design of type III-B rotaxane dendrimers. Two azo-based G1/G2 and four new G1 and G2 hetero type III-B rotaxane dendrimers were synthesized and characterized by ¹H NMR spectroscopy and electrospray ionization mass spectrometry.     

Triazine dendrimers by divergent and convergent methods

Two types of dendrimers with a 1,3,5‐triazine ring at the branch point were synthesized by divergent and convergent methods. The divergent method began with 2,4,6‐tris(p‐nitroanilino)‐1,3,5‐triazine as a trifunctional core. Each cycle involved the reduction of the peripheral NO₂ group followed by a reaction with 2‐chloro‐4,6‐bis(p‐nitroanilino)‐1,3,5‐triazine. The synthetic cycle was completed by the coupling with 2,4‐dianilino‐6‐chloro‐1,3,5‐triazine (DACT) to eventually accomplish second‐generation dendrimers ([G2]₃‐C) bearing 12 benzene rings at their edge. The convergent approach started with the reaction of DACT with p‐nitrophenol to give rise to 2,4‐dianilino‐6‐(p‐nitrophenoxy)‐1,3,5‐triazine. The synthetic cycle consisted of reduction of the NO₂ group and coupling with 2,4‐dichloro‐6‐(p‐nitrophenoxy)‐1,3,5‐triazine. The final step was the connection of each monodendron with cyanuric chloride to produce tridendron; in this way, the second‐generation dendrimer ([EG2]₃‐C) was obtained. Gel permeation chromatography analyses indicated the aggregation of dendrimers in solution. Ultraviolet spectroscopic analyses revealed that the larger dendrimer had a more conjugated electron system from the core to the periphery. The thermal properties were evaluated by thermogravimetric analysis (TGA); excellent heat resistance was indicated, especially in [G1]₃‐C, which included alternately imine‐like nitrogen‐linked 1,3,5‐triazine and benzene rings. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4385–4395, 2000     

Photoresponsive nanocarriers based on PAMAM dendrimers with a o‐nitrobenzyl shell

Gn (n = 3, 4, and 5) poly(amidoamine) (PAMAM) dendrimers were synthesized and peripherally modified with photocleavable o‐nitrobenzyl (NB) groups by reacting o‐nitrobenzaldehyde with the terminal amine groups of PAMAM dendrimers, followed by reducing the imine to amine groups with NaBH₄. The NB‐modified dendrimers, Gn‐NB (n = 3, 4, and 5), were characterized by nuclear magnetic resonance and fourier transform infrared spectroscopy. The results showed that the NB groups were successfully attached on the periphery of the dendrimers with near 100% grafting efficiency. Such a photosensitive NB shell could be cut off on irradiation with 365 nm ultraviolet (UV) light. The encapsulation and release of guest molecules, that is, salicylic acid (SA) and adriamycin (ADR), by Gn‐NB were explored. The encapsulation capability of these dendrimers was found to increase as the guest molecular size was decreased and have dependence on the generation of dendrimers as well. For both of SA and ADR, the average encapsulation numbers per dendrimer decreased in the order of G4‐NB > G5‐NB > G3‐NB, indicating that the fourth generation dendrimer was a better container for the guest molecules. The rate of SA release was found to be greater with UV irradiation than that without, suggesting that the NB‐shelled PAMMAM dendrimers could function as a molecular container/box with photoresponsive characteristics. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 551–557, 2010     

Dendritic chelating agents. 1. Cu(II) binding to ethylene diamine core poly(amidoamine) dendrimers in aqueous solutions

This paper describes an investigation of the uptake of Cu(II) by poly(amidoamine) (PAMAM) dendrimers with an ethylenediamine (EDA) core in aqueous solutions. We use bench scale measurements of proton and metal ion binding to assess the effects of (i) metal ion-dendrimer loading, (ii) dendrimer generation/terminal group chemistry, and (iii) solution pH on the extent of binding of Cu(II) in aqueous solutions of EDA core PAMAM dendrimers with primary amine, succinamic acid, glycidol, and acetamide terminal groups. We employ extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the structures of Cu(II) complexes with Gx-NH2 EDA core PAMAM dendrimers in aqueous solutions at pH 7.0. The overall results of the proton and metal ion binding measurements suggest that the uptake of Cu(II) by EDA core PAMAM dendrimers involves both the dendrimer tertiary amine and terminal groups. However, the extents of protonation of these groups control the ability of the dendrimers to bind Cu(II). Analysis of the EXAFS spectra suggests that Cu(II) forms octahedral complexes involving the tertiary amine groups of Gx-NH2 EDA core PAMAM dendrimers at pH 7.0. The central Cu(II) metal ion of each of these complexes appears to be coordinated to 2-4 dendrimer tertiary amine groups located in the equatorial plane and 2 axial water molecules. Finally, we combine the results of our experiments with literature data to formulate and evaluate a phenomenological model of Cu(II) uptake by Gx-NH2 PAMAM dendrimers in aqueous solutions. At low metal ion-dendrimer loadings, the model provides a good fit of the measured extent of binding of Cu(II) in aqueous solutions of G4-NH2 and G5-NH2 PAMAM dendrimers at pH 7.0.     

Morphological change of gold-dendrimer nanocomposites by laser irradiation

Gold-dendrimer nanocomposites are prepared in aqueous solutions in the presence of poly(amidoamine)dendrimers (PAMAM) (generation 3 and 5) or poly(propyleneimine)dendrimers (PPI) (generation 3 and 4) by wet chemical NaBH(4) method. Thus prepared gold-dendrimer nanocomposites are irradiated by laser at 532 nm. UV-vis absorption spectroscopy and transmission electron microscopy reveal that the gold nanoparticles grow with the laser irradiation time as well as the fluence of the laser; in particular, the gold nanoparticles prepared at lower concentrations of PAMAM dendrimer as well as lower generations of PAMAM grow significantly. On the other hand, in the case of PPI dendrimers, the gold nanoparticles hardly grow by irradiation. In addition, dynamic light-scattering measurements show that the laser irradiation markedly promotes the association of the gold-PAMAM G3 dendrimer nanocomposites compared to that of the gold-PAMAM G5 dendrimer nanocomposites, while the sizes of association for the gold-PPI G3, G4 dendrimer nanocomposites hardly change by laser irradiation.     

Two Distinct Thermal Stabilities of DNA and Enzymatic Activities of DNase I in a Multistep Assembly with Carbazole Ligands: Different Binding Characteristics for Duplex and Quadruplex DNA

A partially hydrophobic carbazole ligand ((Im⁺)₂Cz: 2,2′‐(9‐ethyl‐9 H‐carbazole‐3,6‐diyl)bis(ethyne‐2,1‐diyl)bis(1,3‐dimethyl‐1 H‐imidazol‐3‐ium)) adopts two different binding states (binding states I and II) in its interactions with calf‐thymus (ct‐) DNA. Two distinct binding states were identified by biphasic UV/Vis and circular dichroism (CD) spectral changes during the titration of DNA into the carbazole ligand. At low concentrations of ct‐DNA, (Im⁺)₂Cz binds to nearly every part of ct‐DNA (binding state I). By contrast, an increased concentration of ct‐DNA results in a switch in the DNA‐binding state, so that the ligands are bound per five DNA base pairs. Similarly, a monocationic carbazole ligand (Im⁺Cz: 2‐((6‐bromo‐9‐ethyl‐9 H‐carbazol‐3‐yl)ethynyl)‐1,3‐dimethyl‐1 H‐imidazol‐3‐ium) also shows biphasic UV/Vis spectral changes during the titration of ct‐DNA into Im⁺Cz, which suggests two different binding states of the Im⁺Cz ligand with ct‐DNA. The stepwise equilibrium of the ligand–DNA‐complex formation is capable of switching the thermal stability of ct‐DNA, as well as the enzymatic activity of deoxyribonuclease (DNase I). In binding state I, the (Im⁺)₂Cz ligands interact with nearly every base pair in ct‐DNA and stabilize the double‐helix structure, which results in a larger increase in the melting temperature of the ct‐DNA than that observed with binding state II. On the other hand, the (Im⁺)₂Cz ligand significantly reduces the enzymatic activity of DNase I in binding state I, although the enzymatic activity is recovered once the binding state of the ligand–DNA complex is changed to binding state II. The (Im⁺)₂Cz ligand was also employed as a binder for G‐quadruplex DNA. In contrast to the stepwise complex formation between (Im⁺)₂Cz and ct‐DNA, (Im⁺)₂Cz shows a monotonous UV/Vis spectral response during the titration of G‐quadruplex DNA into (Im⁺)₂Cz, which suggests a single binding state for (Im⁺)₂Cz with G‐quadruplex DNA.     

Fluorescence and aggregation behavior of poly(amidoamine) dendrimers peripherally modified with aromatic chromophores: the effect of dendritic architectures

PAMAM dendrimers of the zeroth to fifth generation (G0-5) have been peripherally modified with phenyl, naphthyl, pyrenyl, and dansyl chromophores. Their fluorescence behaviors are strongly affected by the dendritic architectures at different generations. These dendrimers modified with hydrophobic chromphores can self-organize into vesicular aggregates at the low generations G0-3 in water. The size and aggregation number of these vesicles decrease with increasing generation from G0 to G3. Critical aggregation concentration determined by fluorescence spectroscopy reveals that these aggregates can be favorably formed in the order of G3 > G2 > G1. In contrast to the vesicles made from traditional amphiphilic compounds, these dendrimer-based vesicles are very adhesive due to the H-bonding interaction and entanglement of dendritic branches located in the outer layer. A large number of multivesicle assemblies, i.e., "twins" and "quins" consisting of two and five vesicles, were clearly identifiable with transmission electron (TEM) and atomic force microscopy. For the dendrimers with peripheral pyrenyl chromophores, triangle-like vesicles were observed in water. The hydrophobic interphase thickness of the vesicular bilayer is ca. 2.0-3.2 nm determined by fluorescence resonance energy transfer methods, which agrees well with the thickness directly observed with TEM.     

Adsorption behaviors of poly(amido amine) dendrimers with an azacrown core and long alkyl chain spacers on solid substrates

Adsorption behaviors of functional poly(amido amine) dendrimers with an azacrown core and long alkyl chain spacers were investigated on gold and self-assembled monolayer (SAM) by means of time course attenuated total reflection-surface enhanced infrared absorption and surface plasmon resonance spectroscopies. While 1.5th and 2.5th generation (G1.5 and G2.5) ester-terminated dendrimers were slightly adsorbed on all substrates examined, the adsorption of G2 amine-terminated dendrimer increased in the order dodecanethiol SAM相似文献   

Amine and ammonium functionalization of chloromethylsilane-ended dendrimers. Antimicrobial activity studies

Novel amine- and ammonium-terminated carbosilane dendrimers of type G(n)-[Si{CH(2)O-(C(6)H(4))-3-NMe(2)}](x) or G(n)-[Si{CH(2)O-(C(6)H(4))-3-NMe(3)(+)I(-)}](x) have been synthesized and characterized up to second generation by phenolysis of (chloromethyl)silyl-terminated dendrimers with 3-dimethylamine phenol and subsequent quaternization with methyl iodide. Quaternized carbosilane dendrimers are stable in protic solvents and can be solubilised in water after the addition of less than 1% of dimethyl sulfoxide. A study of the antimicrobial activity of these cationic dendrimers of first and second generation against both gram-positive and gram-negative bacteria is also described. The results obtained demonstrate that the new ammonium-terminated carbosilane dendrimers can be considered as multivalent biocides.