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Species of Leishmania and Trypanosoma genera are the causative agents of relevant parasitic diseases. Survival inside their hosts requires the existence of a potent antioxidant enzymatic machinery. Four iron superoxide dismutases have been described in trypanosomatids (FeSODA, FeSODB1, FeSODB2, and FeSODC) that hold a potential as therapeutic targets. Nonetheless, very few studies have been developed that make use of the purified enzymes. Moreover, FeSODC remains uncharacterised in Leishmania. In this work, for the first time, we describe the purification and enzymatic activity of recombinant versions of the four Leishmania FeSOD isoforms and establish an improved strategy for developing inhibitors. We propose a novel parameter [(V*cyt. c − Vcyt. c)/Vcyt. c] which, in contrast to that used in the classical cytochrome c reduction assay, correlates linearly with enzyme concentration. As a proof of concept, we determine the IC50 values of two ruthenium carbosilane metallodendrimers against these isoforms.

Cisplatin (cis-diamminedichloroplatinum(II)) is a potent chemotherapeutic agent commonly used to treat cancer. However, its use also leads to serious side effects, such as nephrotoxicity, ototoxicity, and cardiotoxicity, which limit the dose that can be safely administered to patients. To minimize these problems, dendrimers may be used as carriers for cisplatin through the coordination of their terminal functional groups to platinum. Here, cisplatin was conjugated to half-generation anionic PAMAM dendrimers in mono- and bidentate forms, and their biological effects were assessed in vitro. After preparation and characterization of the metallodendrimers, their cytotoxicity was evaluated against several cancer cell lines (A2780, A2780cisR, MCF-7, and CACO-2 cells) and a non-cancer cell line (BJ cells). The results showed that all the metallodendrimers were cytotoxic and that the cytotoxicity level depended on the cell line and the type of coordination mode (mono- or bidentate). Although, in this study, a correlation between dendrimer generation (number of carried metallic fragments) and cytotoxicity could not be completely established, the monodentate coordination form of cisplatin resulted in lower IC50 values, thus revealing a more accessible cisplatin release from the dendritic scaffold. Moreover, most of the metallodendrimers were more potent than the cisplatin, especially for the A2780 and A2780cisR cell lines, which showed higher selectivity than for non-cancer cells (BJ cells). The monodentate G0.5COO(Pt(NH3)2Cl)8 and G2.5COO(Pt(NH3)2Cl)32 metallodendrimers, as well as the bidentate G2.5COO(Pt(NH3)2)16 metallodendrimer, were even more active towards the cisplatin-resistant cell line (A2780cisR cells) than the correspondent cisplatin-sensitive one (A2780 cells). Finally, the effect of the metallodendrimers on the hemolysis of human erythrocytes was neglectable, and metallodendrimers' interaction with calf thymus DNA seemed to be stronger than that of free cisplatin. [ABSTRACT FROM AUTHOR]

Species of Leishmania and Trypanosoma genera are the causative agents of relevant parasitic diseases. Survival inside their hosts requires the existence of a potent antioxidant enzymatic machinery. Four iron superoxide dismutases have been described in trypanosomatids (FeSODA, FeSODB1, FeSODB2, and FeSODC) that hold a potential as therapeutic targets. Nonetheless, very few studies have been developed that make use of the purified enzymes. Moreover, FeSODC remains uncharacterised in Leishmania . In this work, for the first time, we describe the purification and enzymatic activity of recombinant versions of the four Leishmania FeSOD isoforms and establish an improved strategy for developing inhibitors. We propose a novel parameter [( V * cyt. c  -  V cyt. c )/ V cyt. c ] which, in contrast to that used in the classical cytochrome c reduction assay, correlates linearly with enzyme concentration. As a proof of concept, we determine the IC 50 values of two ruthenium carbosilane metallodendrimers against these isoforms.

Cisplatin (cis-diamminedichloroplatinum(II)) is a potent chemotherapeutic agent commonly used to treat cancer. However, its use also leads to serious side effects, such as nephrotoxicity, ototoxicity, and cardiotoxicity, which limit the dose that can be safely administered to patients. To minimize these problems, dendrimers may be used as carriers for cisplatin through the coordination of their terminal functional groups to platinum. Here, cisplatin was conjugated to half-generation anionic PAMAM dendrimers in mono- and bidentate forms, and their biological effects were assessed in vitro. After preparation and characterization of the metallodendrimers, their cytotoxicity was evaluated against several cancer cell lines (A2780, A2780cisR, MCF-7, and CACO-2 cells) and a non-cancer cell line (BJ cells). The results showed that all the metallodendrimers were cytotoxic and that the cytotoxicity level depended on the cell line and the type of coordination mode (mono- or bidentate). Although, in this study, a correlation between dendrimer generation (number of carried metallic fragments) and cytotoxicity could not be completely established, the monodentate coordination form of cisplatin resulted in lower IC50 values, thus revealing a more accessible cisplatin release from the dendritic scaffold. Moreover, most of the metallodendrimers were more potent than the cisplatin, especially for the A2780 and A2780cisR cell lines, which showed higher selectivity than for non-cancer cells (BJ cells). The monodentate G0.5COO(Pt(NH3)2Cl)8 and G2.5COO(Pt(NH3)2Cl)32 metallodendrimers, as well as the bidentate G2.5COO(Pt(NH3)2)16 metallodendrimer, were even more active towards the cisplatin-resistant cell line (A2780cisR cells) than the correspondent cisplatin-sensitive one (A2780 cells). Finally, the effect of the metallodendrimers on the hemolysis of human erythrocytes was neglectable, and metallodendrimers’ interaction with calf thymus DNA seemed to be stronger than that of free cisplatin.

A cytochrome P450 3A4 (CYP3A4) based enzymatic biosensor was developed with the incorporation of a first‐generation copper polypropyleneimine (CuPPI) metallodendrimer for the detection of anti‐tuberculosis (anti‐TB) drugs. The development of an electrochemical phenotype biosensor for this purpose is still vital since it aids in the ongoing fight against TB by determining metabolic profile. This allows TB treatment to be tailored on an individual patient basis, minimise adverse drug reactions and improve quality of life in TB patients. This simple biosensor was constructed via physical adsorption of CuPPI onto a gold electrode with subsequent electrostatic attachment of CYP3A4. The biosensor was successful in detecting all four first line anti‐TB drugs i. e. isoniazid, ethambutol, pyrazinamide and rifampicin with limits of detection ranging from 0.02244 to 0.1072 nM in 0.1 M phosphate buffer. The developed biosensor was then applied towards "real samples" in the form of spiked synthetic urine and plasma. Calibration curves were carried out in the complex matrices, which were diluted with 0.1 M PB. These yielded good LOD in the range of ultra‐low micromolar concentration i. e. 0.165–0.884 μM across all drugs. Recovery studies were also successful when detecting the real tablets in both plasma and urine with results ranging from 91.5 % to 108.5 %. [ABSTRACT FROM AUTHOR]

In this mini-review article the concept of electron reservoir materials developed in the author's laboratory is summarized. Starting from mono- and bimetallic electron reservoir complexes and their electronic and catalytic properties this concept extends to macromolecular electron-reservoir devices including metallodendrimers, metallopolymers and macromolecule-stabilized late transition-metal nanoparticles. The electronic switch in these devices is discussed as well as the structure-dependent possibilities to stabilize both utilized redox forms. Catalytic and energy-related applications involving redox metallomacromolecules and nanoparticles and their potential extension are briefly discussed. Giant ferrocene and pentamethylferrocene-based dendrimers and polymers are typical electron reservoir macromolecules that have been isolated in both oxidized and reduced forms with the ability to carry a large flow of electrons at about the same potential. The dramatic structural and size changes of the metallomacromolecules upon redox switch is reminiscent of molecular machines. [ABSTRACT FROM AUTHOR]

Triazine-based heterogeneous Pd/Cu-bimetallodendrimer Nanoparticle (Pd/Cu-BMDNP) has been synthesized by sequential loading method from palladium containing metallodendrimer (Pd-MD) which was prepared by the reaction of 2,4,6-Triamine-1,3,5-triazine (melamine) with substituted benzoyl chloride using (Ph 3 P) 2 PdCl 2 in DMSO at 90 °C. SEM and EDX of Pd/Cu-BMDNP showed the nanosized aggregated spherical surface morphology and the presence of Palladium and copper of the NP. Also, the phase was detected as Face Centered Cubic (FCC) structure by XRD analysis. In addition, the average particle size of Pd/Cu bimetallic catalyst was identified as 12–13 nm by TEM investigation. Greater thermal stability of Pd/Cu-BMDNP than Pd-MD was detected from TG and DSC experiments. The Pd-metallodendrimer has been also characterized by IR, 1H NMR, 13C NMR, SEM, EDX, Mass, TG and DSC techniques. The simple recoverability, high reusability, low amount of catalyst loading, negligible amount of catalyst leaching of the heterogeneous Pd/Cu-BMDNP have made more effective catalyst than homogeneous Pd-metallodendrimer for the C–C cross-coupling reaction such as Heck, Glaser, Sonogashira and Suzuki-Miyaura in excellent yields. [ABSTRACT FROM AUTHOR]

Biofilm formation is a critical health concern, involved in most human bacterial infections. Combatting this mechanism, which increases resistance to traditional antibiotics and host immune defences, requires novel therapeutic approaches. The remarkable biocide activity and the monodispersity of carbosilane metallodendrimers make them excellent platforms to evaluate the impact of different structural parameters on the biological activity. In this work, we explore the influence of iminopyridine ring substituents on the antibacterial activity against planktonic and biofilm Staphylococcus aureus. New families of first-generation Ru(II) and Cu(II) metallodendrimers were synthesised and analysed, in comparison to the non-substituted counterparts. The results showed that the presence of methyl or methoxy groups in meta position to the imine bond decreased the overall positive charge on the metal ion and, subsequently, the activity against planktonic bacteria. However, it seemed a relevant parameter to consider for the prevention of biofilm formation, if they contribute to increasing the overall lipophilicity. An optimum balance of the charge and lipophilicity of the metallodrug, accomplished through structural design, will provide effective biocide agents against bacteria biofilms.

Graphical abstract Highlights • Ruthenium(II) carbosilane metallodendrimers containing arene moieties were evaluated. • Metallodendrimers are promising antitumor agents against resistant prostate cancer. • In vitro , they displayed cytotoxic, antiproliferative and antimetastatic behaviors. • In vivo , metallodendrimers inhibited tumor growth and delayed the tumor progression. • They exerted a selective action in the tumor and a fast elimination via urine route. Abstract Background Prostate cancer is the fifth cause of death among men worldwide. Patients suffering resistant prostate tumor, unresponsive to common treatments, can only be treated with palliative therapy. Materials and methods Ruthenium(II) carbosilane metallodendrimers containing arene moieties were evaluated as a novel antitumor nanotherapy against resistant prostate cancer. The preclinical evaluation included relevant in vitro , ex vivo and in vivo assays, in an experimental mice model of human prostate cancer. Results Promising cytotoxic, antiproliferative and antimetastatic behaviors were observed. After treatment with these nanocompounds, mice underwent a significant reduction of tumor volume, in comparison to non-treated animals. Conclusions The selective antitumor behavior and the lack of toxicity, potentially make ruthenium(II) metallodendrimers promising agents for cancer therapy. [ABSTRACT FROM AUTHOR]

Abstract Ruthenium (II) metallodendrimer (RuDen) and the wheel-shaped Cu 20 -Tungstophosphate [Cu 20 Cl(OH) 24 (H 2 O) 12 (P 8 W 48 O 184)]25− heteropolyanion (HPA) were successfully immobilised on a glassy carbon electrode through employment of the Layer-by-Layer (LBL) deposition method. The fabricated (Cu 20 P 8 W 48 /RuDen) multilayer films have been investigated with cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and surface based techniques. The layers exhibited well behaved redox activity for both the HPA and RuDen moieties and exhibited good stability towards redox cycling and associated thin layer behaviour. The charge transfer resistance (R ct) and Warburg Impedance (Z w) obtained values for the layers by EIS indicated an increase the compactness of the layers upon construction. The (Cu 20 P 8 W 48 /RuDen) multilayer films exhibited electrocatalytic ability towards the reduction of iodate. [ABSTRACT FROM AUTHOR]

Two novel metal complexes of modified with 1,8-naphthalimide poly(propylenamine) dendrimer of first generation have been synthesized and characterized. By different analytical methods it was shown that the complex composition includes one ligand and one metal ion. The antimicrobial activity of the dendrimer and metallodendrimers was investigated in vitro against different Gram-positive and Gram-negative bacteria and yeasts. The antibacterial effect of thin polylactide film impregnated with the new compounds was also evaluated. [ABSTRACT FROM AUTHOR]

Cyclotriphosphazene core based metallodendrimers containing six and twelve cobalt bis(dicarbollide) moieties on the periphery have been synthesized. The ring opening reaction of the cyclic oxonium derivative of the cobalt bis(dicarbollide) anion, [3,3′-Co(8-C 4 H 8 O 2 -1,2-C 2 B 9 H 10 )(1′,2′-C 2 B 9 H 11 )], has been efficiently used for the synthesis of the dendrimers. The newly synthesized dendrimers have been characterized by 1 H, 13 C, 11 B, 31 P NMR and MALDI-TOF mass spectrometry, and the UV-Vis spectroscopy was used to determine the number of cobalt bis(dicarbollide) units present in the dendrimer molecules. These dendrimers are extremely thermally robust, with 83% and 87% mass retention at 600 °C. [ABSTRACT FROM AUTHOR]

Dendrimers exhibit unique interactions with cell membranes, arising from their nanometric size and high surface area. To a great extent, these interactions define their biological activity and can be reported in situ by spin-labelling techniques. Schiff-base carbosilane ruthenium (II) metallodendrimers are promising antitumor agents with a mechanism of action yet to explore. In order to study their in situ interactions with model cell membranes occurring at a molecular level, namely cetyltrimethylammonium bromide micelles (CTAB) and lecithin liposomes (LEC), electron paramagnetic resonance (EPR) was selected. Both a spin probe, 4-(N,N-dimethyl-N-dodecyl)ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl bromide (CAT12), able to enter the model membranes, and a spin label, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently attached at newly synthesized heterofunctional dendrimers, were used to provide complementary information on the dendrimer−membrane interactions. The computer-aided EPR analysis demonstrated a good agreement between the results obtained for the spin probe and spin label experiments. Both points of view suggested the partial insertion of the dendrimer surface groups into the surfactant aggregates, mainly CTAB micelles, and the occurrence of both polar and hydrophobic interactions, while dendrimer−LEC interactions involved more polar interactions between surface groups. We found out that subtle changes in the dendrimer structure greatly modified their interacting abilities and, subsequently, their anticancer activity.

Antibiotic resistance is currently one of the main threats to public health security. Biofilm formation is a resistance mechanism that is responsible for most human bacterial infections and requires new and effective therapeutic approaches, such as those provided by nanotechnology. In this work, the antibacterial effect of carbosilane metallodendrimers with different metals (copper(II) and ruthenium(II)), ligands (chloride and nitrate) and generations (generation 0, 1 and 2) has been studied using planktonic Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Furthermore, the ability of the metallodendrimers to avoid the formation of S. aureus biofilms was also evaluated. The results showed a promising biocide activity in both types of planktonic bacteria, especially for first-generation dendrimers, which arises from the metal complexation to the dendrimer. Cu(II) metallodendrimers require lower concentration than Ru(II) counterpart to inhibit the production of S. aureus biofilms, but none produce hemolysis at the inhibitory concentrations and can be safely used as antibacterial agents. In particular, the first-generation Cu(II) metallodendrimer with nitrate ligands displayed the most promising properties to continue with further studies in both planktonic cells and biofilms.

Poly(propylenimine) dendrimers from first and third generations modified with 1,8-naphthalimide units and their Zn(II) complexes have been investigated by absorption and fluorescence spectroscopy. These dendrimers have been deposited on a cotton cloth by the extraction method, producing yellow-colored textile materials. They have been characterized by defining their color coordinates L*a*b*, XYZ and xy. The antimicrobial activity of dendrimers has been investigated in vitro against model gram-positive and gram-negative bacteria and yeasts. Being deposited onto the surface of cotton fabric, the studied dendrimers reduced bacterial growth and prevented the formation of bacterial biofilm. Anticancer and cytotoxicity activities have also been performed against HeLa and Lep-3 human tumor cell lines as model systems.

The construction of a new family of multiferrocenes end-capped metallodendrimers H1–4 with various generations via coordination-driven self-assembly was described. The structures of these metallodendrimers H1–4 were characterized by multinuclear NMR { 1 H and 31 P} spectroscopy, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and the PM6 semiempirical molecular orbital method. Insight into the structure and electronic properties of these supramolecules was obtained through electrochemical studies. [ABSTRACT FROM AUTHOR]

A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD-Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, L-leucine; R, L-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD-Co(II)|AgNPs aptatoxisensor was fabricated with 5' thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD-Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 μg·L-1 and the calculated limit of detection (LOD) was 0.04 μg·L-1. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples. [ABSTRACT FROM AUTHOR]

A series of mono- and polynuclear ferrocenylthiosemicarbazone complexes were prepared via nucleophilic substitution reactions of various amine scaffolds with a ferrocenyl dithiocarbamate. The dithiocarbamate was prepared via a Schiff base condensation reaction. The compounds were characterised using various spectroscopic and analytical techniques including Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy, mass spectrometry and elemental analysis. The ferrocenyl dithiocarbamate and thiosemicarbazone compounds were screened for their preliminary antimicrobial activity against the H37Rv strain of Mycobacterium tuberculosis and the chloroquine-sensitive (CQS) NF54 strain of Plasmodium falciparum . Against M. tuberculosis , the compounds displayed moderate to low activity. The mononuclear and octanuclear complexes were the most active, exhibiting similar MIC values. All compounds displayed moderate activity in the antiplasmodial screening. The mononuclear and trinuclear complexes exhibited enhanced activity compared to the complexes with higher nuclearity. [ABSTRACT FROM AUTHOR]

Dendrimers are hyperbranched macromolecules having a perfectly defined and multifunctionalized structure, constituted of branches emanating radially from a central core. The structure of dendrimers is particularly modular, and can incorporate in different parts coordination complexes. In this review, we will present the interplay between dendrimers and coordination chemistry in three main fields: catalysis, materials, and biology. Most of the examples will be taken from the work done with phosphorus-containing dendrimers, but the pioneering work carried out with other dendrimers will be also presented. One of the major improvements that metallodendrimers have afforded concerning catalysis is their easy recovery and reuse, bridging the gap between homogeneous and heterogeneous catalysis. Another major improvement concerns the “dendritic effect” which can afford impressive outcomes concerning the increase of yield and of enantioselectivity, together with a decrease of the leaching of metals, and consequently of waste. Dendrimers can be used also for the synthesis and stabilization of metallic nanoparticles, for the modification of metallic surfaces at the nanometric scale, and for the synthesis of mesoscopically ordered hybrid materials. Finally metallodendrimers have high potency against cancerous cell lines, and they appear to operate via a different mechanism of action compared with native metallodrugs, opening new avenues for the search of improved anti-cancer agents. [ABSTRACT FROM AUTHOR]

A new series of higher generation cationic N , N- chelating, ruthenium(II) - ethylene-glycol metallodendrimers from first-, second-, third- and fourth-generation pyridylimine-based poly(propylene) dendrimer scaffolds of the type, DAB-(NH 2 ) n (where n = 4, 8, 16 or 32, DAB = diaminobutane) have been prepared. Four metallodendrimers were synthesized, by first reacting DAB-(NH 2 ) n with 2-pyridinecarboxaldehyde; and subsequently reacting the Schiff-base dendritic ligands with the [( η 6 -C 6 H 5 OCH 2 CH 2 OH)RuCl 2 ] 2 dimer, via a bridge-splitting reaction. All compounds were fully characterized using numerous spectroscopic and analytical techniques. In vitro anticancer activities of the complexes were evaluated against the A2780 cisplatin-sensitive and A2780cisR cisplatin-resistant human ovarian carcinoma cell lines and against the non-tumorigenic HEK-293 human embryonic kidney cell line, with the largest dendrimer being the most cytotoxic and selective of all the compounds. A mononuclear model analog was prepared to investigate the size dependency of the systems towards the biological activity. [ABSTRACT FROM AUTHOR]

The paper describes the modification of the periphery of first and third generation poly(propylenamine) dendrimers with 4-amino-1,8-naphthalimide units as well as the formation of their Cu(II) and Zn(II) complexes. The new dendrimers and metal complexes have been characterized by electronic (UV–Vis and fluorescence), FTIR and NMR and MALDI-TOF analytical methods. The results have shown that the Cu(II) and Zn(II) ions form complexes with the dendrimer ligands. Photophysical experiments have been performed in organic solvents of different polarity. The metal complexes formed between the dendrimers and Cu(II) and Zn(II) ions have been studied with regards to potential microbiological activity. In vitro antimicrobial screening of the newly synthesized metallodendrimers revealed promising antimicrobial activity, and the minimum inhibitory concentrations (MICs) of the complexes were determined. The results suggest that the new metal complexes could find application in designing new antimicrobial preparations to control the spread of infections. [ABSTRACT FROM AUTHOR]

A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD–Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 µg·L−1 and the calculated limit of detection (LOD) was 0.04 µg·L−1. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples.

Five paddlewheel-shaped dicopper molecules, 1 , 2a , 2b , 3 and 4 , were synthesized from the reaction of copper acetate and different generations of Fréchet-type dendrons (H G1 –H G4 ). All compounds showed diagnostic bands in their FTIR spectra for the coordinated carboxylate groups with separations of CO asym and CO sym lower than 200 cm −1 suggesting the formation of dimers. A broad absorbance band centered at 700, 695, 695 and 693 nm was observed for compounds 1 – 4 respectively, which is ascribed to the d–d charge-transfer in Cu(II) complexes. A LMCT absorption was observed near 304, 290, 298 and 294 nm for compounds 1 – 4 respectively. Magnetic susceptibility measurements for 1 , 2a and 3 at 1.53, 1.53 and 1.7 respectively in the solid state at 293 K are also suggestive of a dimeric arrangement. The structures of H G2 , 1 , 2a , and 2b were characterized unambiguously with single crystal X-ray diffraction. Three molecules constituted the asymmetric unit of H G2 in the monoclinic space group P 2 1 / n and resulted in dimers formed via intermolecular carboxylic acid-type hydrogen bonds. Compounds 1 , 2a , and 2b contain centrosymmetric paddlewheel-shaped dinuclear copper molecules bridged by four carboxylate groups in syn , syn arrangements. The copper centers in compounds 1 , 2a , and 2b are all coordinated by four carboxylate O atoms in a square pyramidal geometry and the ligands on the apical positions are disordered and occupied by either water, THF, pyridine or methanol molecules. In 1 , all the hydroxyl O atoms are involved in hydrogen bonding, which results in the formation of a 3D network. π–π stacking interactions involving phenyl rings were observed in the crystal structures of H G2 , 2a and 2b. [ABSTRACT FROM AUTHOR]

Highlights: [•] Metal-containing star-shaped molecules and dendrimers functionalized with boron clusters are described. PAMAM, carbosilane or aryl-ether dendrimers are used as platform to covalently attach the boron clusters. • For metallacarboranes-containing dendrimers, the UV-vis is useful to confirm the total functionalization. • The photoluminescence, redox and thermal properties of these metallodendrimers are reported. • Most of these compounds has been proposed as highly promising boron delivery agents for the BNCT. [ABSTRACT FROM AUTHOR]

Highlights: [•] Metallodendrimers containing different metal fragments are reviewed. [•] Different strategies to synthesize heterometallodendrimers are described. [•] Metallodendrimers have been classified depending on the metal location. [ABSTRACT FROM AUTHOR]

The design and self-assembly of pyrene-modified rhomboidal metallodendrimers R1- R6 via directional metal-ligand bonding approach is described. By employing pyrene-containing 120° di-Pt(II) acceptor and appropriate 60° dendritic dipyridyl donors, a variety of [ G-1]-[ G-3] pyrene-modified rhomboidal metallodendrimers with well-defined shape and size were prepared under mild conditions in high yields. The supramolecular dendrimers were characterized with multinuclear NMR (1H and 31P) and mass spectrometry (CSI-TOF-MS). Isotopically resolved mass spectrometry data support the existence of the pyrene-modified dendrimers with rhomboidal cavities, and NMR data were consistent with the formation of all ensembles. The shape and size of all rhomboidal dendrimers were investigated with the PM6 semiempirical molecular orbital method. Their primary photochemical properties were studied as well. [ABSTRACT FROM AUTHOR]

A series of new dendritic platinum bisferrocenylacetylide complexes have been synthesized utilizing the coupling reaction of trans-Pt complexes with C-H bonds in alkynes as key steps. These new bimetallic dendrimers were fully characterized by multinuclear NMR (1H, 13C, and 31P) and mass spectrometry (MALDI-TOF-MS and CSI-TOF-MS). Electrochemical studies of these complexes were carried out and revealed that all of the redox moieties are stable, independent, and electrochemically active. In addition, all metallodendrimers show one-electron reaction responses, and the increased sizes of these complexes did not exhibit a dramatic influence on the diffusion coefficient. [ABSTRACT FROM AUTHOR]

Abstract: We describe the preparation and structural characterization of a family of chloro-ethynylbenzene complexes containing [(cyclam)Co]3+ units: [(cyclam)CoCl(CCPh)]X (X=Cl (1a), BPh4 (1b)), [(cyclam)2Co2Cl2(p-DEB)]X2 (X=Cl (2a), BPh4 (2b)), [(cyclam)3Co3Cl3(1,3,5-TEB)]X3 (X=Cl (3a), BPh4 (3b)), [(cyclam)2Co2Cl2(1,3,5-TEBH)]X2 (X=Cl (4a), BPh4 (4b)), where the bridging ligands p-DEB and TEB are the bis- and tris-deprotonated anions of 1,4-diethynylbenzene and 1,3,5-triethynylbenzene, respectively. Cyclic voltammetry of [(cyclam)3Co3Cl3(1,3,5-TEB)]Cl3 (3a) suggests that electrochemical reduction of the Co(III) centers to Co(II) is accompanied by complex dissociation resulting from the increased lability of the Co(II) ions. Inclusion of the tetraphenylborate anions in 1b–4b allows for the possibility of stepwise acetylide substitution by imparting complex cation solubility in tetrahydrofuran: trans-[(cyclam)Co(CCPh)2](BPh4) (5) is prepared by mixing LiCCPh with 1b. Isolation of 5 demonstrates the feasibility of metallodendrimer synthesis using octahedral first-row transition metal nodes, which awaits demonstration. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of novel amidoamine-based metallodendrimers with heterobimetallic end-grafted amidoferrocenyl-palladium-allyl chloride units is described. Dendrimer (Fe((η5-C5H4PPh2)(η5-C5H4))C(O)HNCH2CH2NHC(O)CH2CH2)N[CH2CH2N(CH2CH2C(O)NHCH2CH2NH-C(O)(Fe(η5-C5H4)(η5-C5H4PPh2)))2]2 (9-Fe) and the corresponding metal species (Fe((η5-C5H4PPh2(Pd(η3-C3H5)Cl))(η5-C5H4))C(O)HNCH2CH2NHC(O)CH2CH2)N[CH2CH2N(CH2CH2C(O)NHCH2CH2NHC(O)(Fe(η5-C5H4)(η5-C5H4PPh2(Pd(η3-C3H5)Cl))))2]2 (9-Fe–Pd) were prepared by a consecutive divergent synthesis methodology including addition–amidation cycles, standard peptide coupling, and coordination procedures. For comparative reasons also the monomeric and dimeric molecules (Fe(η5-C5H4PPh2)(η5-C5H4C(O)NH n C3H7)) (5-Fe) and [Fe(η5-C5H4PPh2)(η5-C5H4C(O)NHCH2)]2 (6-Fe) as well as N(CH2CH2C(O)NHCH2CH2NHC(O)(Fe(η5-C5H4)(η5-C5H4PPh2)))3 (7-Fe) and [CH2N(CH2CH2C(O)NHCH2CH2NHC(O)(Fe(η5-C5H4)(η5-C5H4PPh2)))2]2 (8-Fe) were prepared from Fe(η5-C5H4PPh2)(η5-C5H4CO2H) (3). Using [Pd(η3-C3H5)Cl]2 (4) as palladium source heterobimetallic metallodendrimers (Fe(η5-C5H4PPh2(Pd(η3-C3H5)Cl))(η5-C5H4C(O)NH n C3H7)) (5-Fe–Pd), [Fe(η5-C5H4PPh2(Pd(η3-C3H5)Cl))(η5-C5H4C(O)NHCH2)]2 (6-Fe–Pd), N(CH2CH2C(O)NHCH2CH2NHC(O)(Fe(η5-C5H4)(η5-C5H4PPh2(Pd(η3-C3H5)Cl))))3 (7-Fe–Pd) and [CH2N(CH2CH2C(O)NHCH2CH2NHC(O)(Fe(η5-C5H4)(η5-C5H4PPh2(Pd(η3-C3H5)Cl))))2]2 (8-Fe–Pd) were synthesized. Additionally, seleno-phosphines of 5-Fe–Se and 9-Fe–Se, respectively, were prepared by addition of elemental selenium to 5-Fe or 9-Fe to estimate their σ-donor properties. The palladium-containing amidoamine supports are catalytically active in the Heck–Mizoroki cross-coupling of iodobenzene with tert-butyl acrylate. The catalytic data are compared to those obtained for the appropriate mononuclear and dinuclear compounds 5-Fe–Pd and 6-Fe–Pd. This comparison confirms a positive cooperative effect. The mercury drop test showed that (nano)particles were formed during catalysis, following on heterogeneous carbon–carbon cross-coupling. [Copyright &y& Elsevier]

Abstract: A metallodendrimer-based electrochemical DNA biosensor was constructed by a layer-by-layer assembly of cobalt(II) salicylaldiimine metallodendrimer (SDD–Co(II)) and a 21 bases oligonucleotide NH2-5′-GAGGAGTTGGGGGAGCACATT-3′ (pDNA) on a gold electrode. The complementary oligonucleotide was 5′-AATGTGCTCCCCCAACTCCTC-3′ (tDNA). UV–visible spectra of SDD–Co(II) in 1:1 (v/v) acetone–ethanol solution showed absorption bands at 325nm and 365–420nm related to π–π* intra-dendrimer transitions and d–π* metal-dendrimer charge transfer transitions, respectively. Square-wave voltammetry (SWV) characterisation of the Au|SDD–Co(II)|pDNA biosensor system in phosphate buffer saline solution of pH 7.4, indicated a reversible one-electron electrochemical process with a formal potential, E°′, value of +210mV. Electrochemical impedance spectroscopy (EIS) data confirmed that the hybridisation of the biosensor''s pDNA with the tDNA to form double-stranded DNA (dsDNA) resulted in an increase of the impedimetric charge transfer resistance, R ct, value from 6.52 to 12.85kΩ. The limit of detection (LOD), calculated as 3σ of the background noise, and sensitivity of the sensor were 1.29kΩ/nmolL−1 and 0.34pmolL−1, respectively. [Copyright &y& Elsevier]

Abstract: The preparations of novel platinum and copper metallodendrimers are reported. Surface modified first generation (G0) poly(amidoamine) (PAMAM) dendritic Schiff base, prepared via a condensation reaction was coordinated with platinum chloride and copper chloride yielding [G0-Py4-[PtCl2]4] (4D) and [G0-Py4-[CuCl2]7] (7E) respectively. These functionalized hyper-branched complexes were characterized by IR spectroscopy and CHN analysis. 4D was further characterized through 1H and 13C spectroscopy, while 7E was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI/TOF) Mass Spectrometer. The cytotoxic effects of the compounds against cells of neoplastic origin (MOLT-4, MCF-7) and cells of benign origin (Chang Liver) were studied. Their cytotoxicities were then compared to their mono-nuclear analogues, [(MeCONHCH2CH2Nl2)] (1D) and [(MeCONHCH2CH2Nl2)] (1E). The multi-nuclear complexes showed increased cytotoxic activities as compared to their respective mono-nuclear compounds. Most notably, significant inhibitions were observed for 7E on all cell lines, in which its IC50 values were 11.1±0.6, 10.2±1.5 and 8.7±0.7μM against MOLT-4, MCF-7 and Chang Liver cells respectively. The multi-nuclear copper-based complexes (7E) are therefore most effective against a cancer cell line (MOLT-4) and a cisplatin-resistant cell line (MCF-7). [Copyright &y& Elsevier]

Abstract: Several dendritic bridging ligands were designed and synthesized to develop more sensitive and efficient electrochemiluminescent (ECL) polynuclear Ru(II) complexes. Various types of novel two-armed, four-armed and six-armed tris(bipyridyl)ruthenium core dendrimers were synthesized by coordinating dendritic polybipyridyl ligands with Ru(II) complexes, and the effect of the ligand and the dendritic network on the ECL characteristics were studied. Their electrochemical redox potentials, UV, photoluminescence (PL), and relative ECL intensities were also investigated in detail. The synthesized metallodendrimers exhibited strong metal-to-ligand charge transfer (MLCT) absorption at 428–451nm and emission at 591–601nm. Most of the newly synthesized metallodendrimers showed enhanced ECL intensities compared to the reference complex, [Ru(o-phen)3](PF6)2. In particular, the ECL intensities of the six-armed heptanuclear ruthenium complexes were almost four times greater than that of [Ru(o-phen)3]2+. These metallodendrimers could be utilized as efficient ECL materials and light emitting devices. [Copyright &y& Elsevier]

Abstract: An electrochemical DNA biosensor (EDB) was prepared using an oligonucleotide of 21 bases with sequence NH2-5′-GAGGAGTTGGGGGAGCACATT-3′ (probe DNA) immobilized on a novel multinuclear nickel(II) salicylaldimine metallodendrimer on glassy carbon electrode (GCE). The metallodendrimer was synthesized from amino functionalized polypropylene imine dendrimer, DAB-(NH2)8. The EDB was prepared by depositing probe DNA on a dendrimer-modified GCE surface and left to immobilize for 1h. Voltammetric and electrochemical impedance spectroscopic (EIS) studies were carried out to characterize the novel metallodendrimer, the EDB and its hybridization response in PBS using [Fe(CN)6]3−/4− as a redox probe at pH 7.2. The metallodendrimer was electroactive in PBS with two reversible redox couples at E°′=+200mV and E°′=+434mV; catalytic by reducing the E pa of [Fe(CN)6]3−/4− by 22mV; conducting and has diffusion coefficient of 8.597×10−8 cm2 s−1. From the EIS circuit fitting results, the EDB responded to 5nM target DNA by exhibiting a decrease in charge transfer resistance (R ct) in PBS and increase in R ct in [Fe(CN)6]3−/4− redox probe; while in voltammetry, increase in peak anodic current was observed in PBS after hybridization, thus giving the EDB a dual probe advantage. [Copyright &y& Elsevier]

Abstract: A novel type of rhenium-containing dendrimers has been prepared and characterized. A series of Schiff base-terminated PAMAM dendrimers were prepared by condensing the terminal amine groups of PAMAM dendrimers with pyridine-2-carboxaldehyde. Complete condensation of the terminal amines was confirmed by 1H NMR spectroscopy. Bromotricarbonylrhenium(I) moieties were introduced onto the surface of these modified PAMAM derivatives by refluxing with bromopentacarbonylrhenium(I). These complexes had been characterized by a variety of analytical and spectroscopic techniques and their IR, NMR, and mass spectra discussed. The crystal structure of the model compound [(CH3CONHCH2CH2Nph name="sbnd" />Py)ReBr(CO)3] confirms a facial configuration of the three carbonyl ligands. UV–Vis absorption spectroscopy suggests that the {Re(CO)3} moieties are quite far apart even in the second generation PAMAM dendrimers and do not interact with one another. In fact, the intensity of the metal-to-ligand (dπ–pπ∗) charge-transfer is a linear function of the number of {Re(CO)3} chromophores. [Copyright &y& Elsevier]

The preparation of a new palladium metallodendrimer is described. The first generation poly(propylene imine) dendrimer [DAB(NH2)4] has been modified by the reaction of the amino end groups with 2-pyridinecarboxaldehyde. Complexation reactions with PdCl2(COD) give rise to a metal-containing dendrimer with PdCl2 moieties bound on the periphery. The new metallodendrimer was used as a catalyst precursor, activated by methylaluminoxane (MAO), for the polymerization of ethylene. High molecular weight, high density polyethylene was obtained. [Copyright &y& Elsevier]