Chungkyun Kim

Ferrocene end-capped dendrimer: synthesis and application to CO gas sensor

Abstract Dendritic carbosilane with ferrocenyl groups on the periphery was prepared. The dendrimer containing 48 SiCl bonds in the fourth generation was prepared by the use of iterative hydrosilation and alkenylation cycles. The title dendrimer was prepared by the reaction of 48 SiCl groups on the peripheral layer of the fourth generation with mono-lithiated ferrocene. The gas sensing abilities of the ferrocene end-capped dendrimer were measured by the use of a sensor device containing the spin-coated dendritic thin film that responded to the various concentrations of CO gas with the linear correlation.

Synthesis of carbosilane dendrimers based on tetrakis(phenylethynyl)silane

Abstract Carbosilane dendrimers of first to third generation were synthesized, using alkynylation/hydrosilation cycles with lithium phenylacetylide and dichloromethylsilane as building blocks and tetrakis(phenylethynyl)silane as a core molecule. The analysis of the 1H- and 13C-NMR, MALDI mass spectra and elemental analysis made it possible to obtain pure and unified dendrimers.

Preparation of ethynylsilane dendrimers

Abstract A dendritic macromolecule containing 144 phenylethynyl groups was created. 1,3,5-tris(dimethylvinylsilyl)benzene (G0) as the core and bis(phenylethynyl)methylsilyl groups as progressing units were used. The first generation (G1P-9Cl) was obtained by the reaction of G0 with trichlorosilane and was followed by the phenylethynyl-group-containing generation (G1-9PA) by the reaction of lithium phenylacethylide. Using the continuous iterative reactions of trichlorosilane and lithium phenylacethylide, the dendritic molecule progressed to the second generation (G2-27PA). For the formation of a less crowded model, the reaction of the first generation (G1-9PA) with dichloromethylsilane was allowed to progress to the 18 SiCl bonded second generation (G2P-18Cl). After that, by the use of the two iterative reaction mechanisms, the fifth generation with 144 phenylethynyl groups containing the carbosilane dendrimer was prepared.

Preparation and identification of dendritic carbosilanes containing allyloxy groups derived from 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Me(CH 2 CH)SiO) 4 and 1,2-bis(triallyloxysilyl)ethane ((CH 2 CHCH 2 O) 3 SiCH 2 ) 2

Abstract Synthesis and characterization of dendritic macromolecules using 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Me(CH 2 CH)SiO) 4 and 1,2-bis(triallyloxysilyl)ethane ((CH 2 CHCH 2 O) 3 SiCH 2 ) 2 as core molecules and allylalcohol/dichloromethylsilane as a building block have been described. The dendrimers containing dichloromethylsilyl-groups ( GS-1P∼GS-4P and GH-1P∼GH-3P ) were produced by the hydrosilation process of double bonds in vinyl and allyloxy-groups in the GS- n and GH-n type dendrimers with dichloromethylsilane in the presence of a platinum catalyst (Pt/C). The GH- n and GS- n type dendrimers containing allyloxysilyl-groups were prepared by the reaction of GH- n P and GS- nP type dendrimers containing Si–Cl bonds and allylalcohol in the presence of TMED at room temperature. The purification of the prepared GH- n and GS- n type dendrimers used simple column chromatography. The yields of the prepared dendrimers have been obtained almost quantitatively. The analyses of the 1 H- and 13 C-NMR, MALDI mass spectra, and elemental analysis made it possible to obtain the pure and unified dendrimers. In additive manner, the molar absorbities of each generation of GH- n and GS- n type dendrimers show increasing character by the increasing number of double bonds.

2,2':6', 2 -Terpyridine and bis(2,2':6', 2 -terpyridine)ruthenium(II) complex on the dendritic periphery

Abstract 2,2′:6′,2″-Terpyridine end-functionalized dendrimers were prepared utilizing chlorinated siloxane dendrimer and 6-hydroxyhexa-4′-(2,2′:6′,2″-terpyridine) ether. The terpyridine groups on dendrimers accepted the ruthenium chloride ions on the mild condition that produced the paramagnetic ruthenium complex Gn-mTPY-RuCl3. The continual addition of 2,2′:6′,2″-terpyridine to the ruthenium–terpyridine complex on the dendritic periphery progressed to bis(2,2′:6′,2″-terpyridine)ruthenium(II) complex Gn-m[TPY-Ru-TPY] (n=1, m=4; n=2, m=8; n=3, m=16) which revealed diamagnetic property.

Progress toward limiting generation of dendritic ethynylsilanes (PhC?C)4?nMenSi (n = 0-2)

Dendritic carbosilanes based on phenylethynylmethylsilanes (PhCC)4−nMenSi (n = 0–2) as cores were synthesized. The building blocks of the dendrimers consist of double bonds (PhCCHMeSi) in the inner shell and triple bonds [(PhCC)2MeSi] on the outmost periphery. The synthetic methods used the iterative alkynylation and hydrosilation cycle, which was composed of lithium phenylacethylide and dichloromethylsilane. The limiting generation of the dendrimer for the four branching type (PhCC)4Si at a core molecule has 32 phenylethynyl groups on the third generation, 48 for the three branching type (PhCC)3MeSi on the fourth generation, and 64 for the two branching type (PhCC)2Me2Si on the fifth generation. The dendrimers were characterized by the use of NMR, Maldi mass, SEC, DSC, UV as well as elemental analysis.

PREPARATION AND TERMINATION OF CARBOSILANE DENDRIMERS BASED ON A SILOXANE TETRAMER AS A CORE MOLECULE : SILANE ARBOROLS, PART VIII

Abstract Starting with 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-2,4,6,8-tetrasila-1,3,5,7-tetraoxacyclooctane (Me(CH2CH)SiO)4 as a core molecule, a succession of alternate platinum-catalyzed hydrosilations of all vinyl groups with HSiMeCl2, as well as alkenylation with allylmagnesium bromide, provided the third generation (G3) as divergent growth of siloxane-based dendrimers. The reaction path of the repetitive allylation/hydrosilation cycles is controlled with NMR spectroscopic analyses. Each of the two steps provided quantitative yields of pure dendrimers. We also changed the simple construction of the G3P molecule into materials with special functions, such as by adding phenylethynyl and p-bromophenoxy groups on its periphery.

Preparation of dendritic carbosilanes containing ethynyl groups and dicobalt hexacarbonyl clusters on the periphery

Abstract Dendritic carbosilanes have been prepared by the use of 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-2,4,6,8-tetrasila-1,3,5,7-tetraoxacyclooctane (CH2CHMeSiO)4 and 1,2-bis(triallylsilyl)ethane ((CH2CHCH2)3SiCH2)2 as core molecules, diallylmethylsilyl groups ((CH2CHCH2)2MeSi) as building blocks and bisphenylethynylmethylsilyl groups ((PhCC)2MeSi) as terminating groups. The phenylethynyl-group-containing terminal generation is produced by the reaction of the chlorosilylated generation with lithium phenylacethylide. The reaction of dicobalt octacarbonyl Co2(CO)8 with phenylethynyl groups gave the corresponding phenylethynyl hexacarbonyl complexes (2Co2(CO)6·(PhCC)2MeSidendimer) on the periphery. The yields of the prepared dendrimers with phenylethynyl terminal groups and their cobalt carbonyl complexes are obtained nearly quantitatively. They are characterized by the use of spectroscopic analyses (1H-, and 13C-NMR, UV and IR) as well as MALDI mass spectroscopy and elemental analysis.

Diels–Alder reaction of anthracene and N-ethylmaleimide on the carbosilane dendrimer

Abstract Dendrimers with bicyclo-groups on the periphery were synthesized by the Diels–Alder (DA) reaction between anthracene derivatives, which have 24, 48 and 96 end-groups, and N-ethylmaleimide under the mild condition. The structural information of the DA product on dendritic periphery was obtained from hyperfine structural view of 1H-NMR spectroscopy. The purity of the products was determined by size exclusion chromatography.

End-capped carbosiloxane dendrimers with cholesterol and pyridine derivatives

Abstract Dendritic carbosilanes containing 48 and 96 cholesterol as well as pyridine derivatives on the periphery have been prepared. Low generations in the inner shell were prepared by the use of iterative hydrosilation with dichloromethyl silane and alcoholysis with allyl alcohol. The cholesterol and pyridine derivatives containing dendrimers were prepared by the reaction of the SiCl group on parent dendrimers (G4-48Cl and G5-96Cl) and HOR (HOR=cholesterol, p -pyridinepropanol, and p -pyridinealdoxime) in the presence of TMEDA.