Carbosilane Metallodendrimers with Cyclopentadienyldichlorotitanium(IV) End Groups

Abstract

Dendritic polyols of the second and third generation 2G-OH 8 (1), 2G-OH 16 (2), and 3G-OH 16 (3) were prepared by hydroboration/oxidation of allyl-terminated carbosilane dendrimers and used as supports for the immobilization of cyclopentadienyltrichlorotitanium(IV) complexes via alcoholysis. The reaction of 1-3 with CpTiCl 3 gave metallodendrimers 2G-(OTiCpCl 2 ) 8 (4a), 2G-(OTiCpCl 2 ) 16 (5a), and 3G-(OTiCpCl 2 ) 16 (6a), respectively, whereas the reaction of 1 and 3 with CpSi F TiCl 3 (CpSi F = C 5 H 4 SiMe 2 CH 2 CH 2 C 8 F 17 ) yielded peripherally fluorinated metallodendrimers 2G-(OTiCpSi F Cl 2 ) 8 (4b) and 3G-(OTiCpSi F Cl 2 ) 16 (6b). All metallodendrimers were characterized by multinuclear NMR spectroscopy. The suggested structures were supported by comparison with model 1-propoxycomplexes 10a,b. To identify side products of the alcoholysis reaction, hydrolytic behavior of the starting trichloro complexes was studied both in solid state and in solution. The main products of hydrolysis in solution were identified as l-oxocomplexes 8a,b whereas hydrolysis in solid state yielded mainly hydroxycomplexes 7a,b.

Phosphonium carbosilane dendrimers for biomedical applications – synthesis, characterization and cytotoxicity evaluation

“…The core of carbosilane dendrimers was synthesized based on our previous work on synthesis of CS-DMMs functionalized with titanocene moieties. [38][39][40][41] Ammonium and phosphonium groups were connected by quaternization of trimethyl amine or an appropriate phosphine by iodopropyl-terminated dendrimers. To manifest their potential in biomedical applications, we have performed comparative in vitro cytotoxicity studies on three model cell lines.…”

Heterofunctionalized Carbosilane Dendritic Systems: Bifunctionalized Dendrons as Building Blocks versus Statistically Decorated Dendrimers

“…Meanwhile, in our group, partial dansyl-terminated dendrimers were prepared by selective reaction of primary amine-terminated dendrimers with dansyl chloride . An interesting example related to this first approach is the synthesis of carbosilane homodendrimers containing two orthogonal functions or properties introduced by the reagent in the capping reaction that in fact could be considered as a third possible approach …”

“…33 approach is the synthesis of carbosilane homodendrimers containing two orthogonal functions or properties introduced by the reagent in the capping reaction that in fact could be considered as a third possible approach. 34 Considering the second approach, suitable and orthogonal focal points at the dendrons are needed in order to form the socalled Janus dendrimers. Although it requires more synthetic efforts than homofunctional dendrimers, there are outstanding examples in the literature based on scaffolds of different nature.…”

Carbosilane Metallodendrimers with Titanocene Dichloride End Groups

“…; however, we wish to concentrate on cyclopentadienyl complexes at the periphery, since they offer a much higher density of metal sites per unit of polymer material. Although cyclopentadienyl metal complexes were reported to be attached to dendrimers also via atoms other than the carbon of the cyclopentadienyl ring, we concentrated on Cp -ring-attached species, since otherwise the advantage of binding a complex via a spectator Cp ligand would have been lost.…”