Oligo spacer

Fig. 5. [3]Pseudorotaxane dendrimers from complexation of the dendrophanes and molecular rod with rigid oligo(phenylacetylene) spacers and terminal steroid units... 

S. Knapp, T. G. M Dhar, J. Albaneze, S. Gentemann, J. A Potenza, D. Holten, H. J. Schugar, Photoinduced Porphyrin-to-Quinone Electron Transfer across Oligos-pirocydic Spacers , J. Am. Chem. Soc 1991, 113, 4010-4013. 

N. Benfaremo, D.J. Sandman, S. Tripathy, J. Kumar, K. Yang, M.F. Rubner, and C. Lyons, Synthesis and characterization of luminescent polymers of distyrylbenzenes with oligo(ethylene glycol) spacers, Macromolecules, 31 3595-3599, 1998. 

Another series of GSL mimics with oligo-ethylene glycol as spacer have also been obtained successfully using trichloroacetimidate method [482]. In addition, fluorescence-labeled sLex glycosphingolipids have also been chemically synthesized as targets for investigating microdomain formation in membranes [483]. 

Similar results have been presented by Miller and co-workers, who capped the ends of oligo(dihexylfluorene)s and poly(dihexylfluorene)s with Frechet-type dendrons (Figure 7.17C) [73], Annealing experiments coupled with emission studies revealed that G-3 and G-4 dendrons were effective at preventing excimer formation, even when the poly(fluorene) spacer was 50-80 repeat units long. 

Note 3 Examples of polymer backbones are polyacrylates, polymethacrylates, and polysiloxanes the spacers are usually oligomethylene, oligo(oxyethylene), or oligosiloxane. 

Crosslinked poly(styrene) beads (20) were prepared with contain Ru(bpy)2+ anchored at oligo(oxyethylene) spacer group 50). Vigorous stirring was needed for the suspended complex (20) to sensitize the photoreduction of MV2+ in the presence of... 

M. R. Jenneskens, L. W. A highly selective synthesis of monodisperse oligo(ethylene glycols)./. Org. Chem. 1992, 57, 6678-6680. Mougenot, P. Mertens, P. Nguyen, M. Touil-laux, R. Marchand-Brynaert, J. a,o>Difunc-tional perfluorinated spacer arms for polymeric material derivatization. J. Org. Chem. 1996, 61, 408-412. 

Aiming at a Pc-porphyrin dyad 12 with an extremely long rigid linear spacer, Odobel et al. reported the ultra-fast, single step charge separation over a 3.4 nm distance [68,69], The first step of the applied methodology consisted of the preparation of a oligo(phenyleneethynylene) spacer endowed with two terminal alkyne units... 

Schanze and Sauer were the first to report a detailed study of long-range photoinduced ET in a series of metal-organic dyads [94]. These authors synthesized dyads 50a-e (Scheme 22 and Table 4) that comprise a Ru(diimine) + chromophore covalently linked to a p-benzoquinone acceptor using a series of oligo-L-proline peptide spacers. Oligo-proline peptide spacers are used because previous studies suggest that these peptides are conformationally restricted and... 

Several years later Schanze and Cabana reported a study of the distance dependence of photoinduced ET in a second series of oligo-proline bridged dyads (51a-c, Scheme 22 and Table 4) [126,127]. In this study the authors were able to study photoinduced ET in CH3OH, a solvent that is demonstrated to stabilize the extended conformation of the proline spacers [126]. Rate constants for forward ET in 51a-c are determined by using luminescence decay techniques, and an overall distance dependence of 3 = 1.0 A 1 is obtained from the rate data (Table 4). By... 

Abstract This paper proposes new ways of preparation of hybrid silicones, i.e. an alternated multiblock seqnence of silicone and alkyl spacers, via a polycondensation process catalyzed by the tris(pentaflnorophenyl)borane, a water-tolerant Lewis acid, between methoxy and hydrogeno fnnctionalized silanes and siloxanes at room temperature and in the open air. The protocol was first developed with model molecules which led to polydimethylsiloxane (PDMS) chains, in order to seize the best experimental conditions. Several factors were studied such as the contents of each reactants, the nature of the solvent or the rate of addition. The best conditions were then adapted to the synthesis of hybrid silicones, condensing alkylated oligo-carbosiloxanes with methoxy or hydrogeno chain-ends and complementary small molecules. A systematic limitation in final molar masses of hybrid silicones was observed and explained by the formation of macrocycles, which cannot redistribnte or condense further while formed. 

Electron transfer across ferrocene-substituted oligo(phenylene-ethynylene)thiols (System 14) on gold has been studied using the ILIT technique [122] (see above) and electrochemistry [50]. Values of / = 0.57 + 0.02 and 0.36 A were obtained, respectively. Using the electrochemistry method, is 350 s for the 43 A, 36-bond, six-unit conjugated spacer, compared with 1.25 s for the 23 A, 18-bond alkanethiol... 

Other polymers with oligo ethylene oxide) spacers have been observed. The polymers of limura and coworkers, with mesogenic structures 10 and 12 of Table 1 and spacers of di-, tri- and tetraethylene oxide, had X-ray patterns in the melt that were virtually identical to those of the solid This result was also observed for Polymer 37 with a tetraethylene oxide spacer prepared by us Such patterns are consistent with a smectic E mesophase which maintains much of the solid state order in the liquid crystalline melt. 

He et al. [68] examined the effect of adding flexibility to the hydrogen bond acceptor bis-pyridyl units. They attached stilbazole derivatives to either end of differently sized oligo(ethylene oxide) spacers (4) (Fig. 7). Mixing... 

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