Linear oligo

Table I. Mass Spectra of a Linear Oligo(phenylsilylene) and of Hexaphenylcyclohexasilane...

Rochow et al. (29) also report that heating tri- and cyclotetrasilazanes under ammonia leads to the formation of linear oligo-dimethylsilazanes, reaction (12) however, they were never able... 

Fig. 55. Linear oligo-L-lysine bearing aryl mannosides (503) and the quinic acid bioisostere of mannose (504).367,368...

Based on the theory, the separation of enantiomers requires a chiral additive to the CE separation buffer, while diastereomers can also be separated without the chiral selector. The majority of chiral CE separations are based on simple or chemically modified cyclodextrins. However, also other additives such as chiral crown ethers, linear oligo- and polysaccharides, macrocyclic antibiotics, chiral calixarenes, chiral ion-pairing agents, and chiral surfactants can be used. Eew non-chiral separation examples for the separation of diastereomers can be found. 

Very recently, some of us reported novel linear oligo-TB derivatives that exhibit interesting structural features (05OL67). These compounds possess cavitand-shaped binding sites. Effective new stepwise methodology for linear tris-TB 59 was reported (Scheme 11). All three possible diastereoisomers (aa sa ss) were described two of them were isolated and the third was detected after racemization. 

Fig. 13 SPR and AFM analyses of controlled streptavidin recognition on mixed oligo(ethylene glycol) layers, (a) Chemical structure of the mixed layer components linear oligo(ethylene glycol) left) and biotinylated moiety (right), (b) Streptavidin binding at 23°C and (c) at 45°C. (d) SPR sensogram of streptavidin adsorption at 23 and 45°C. Arrows show injections of (a) water (b) streptavidin solution and (c) subsequent water rinse at 23°C and (d) streptavidin solution and subsequent water rinse at 45°C. (e) Tapping mode AFM images in liquid phase after injection of streptavidin solution at 23°C and (f) at 45°C. Reprinted, with permission, from [185]. Copyright (2008) American Chemical Society...

Of various homocoupling procedures derived from the original Glaser process that are still used today, Hay s procedure [4] using catalytic amounts of the biden-tate complexing base TMEDA in polar solvents (e.g. acetone, dichloromethane or o-dichlorobenzene) is most utilized and is the method favored for preparing linear oligo- and polyacetylenes, as outlined in Scheme 2 [5]. 

It can be concluded that the size of the family of linear oligo(phosphole)s is somewhat limited to bi- and tetramers to date, although longer derivatives are potentially accessible via the efficient synthetic routes developed by Mathe/s group. The synthesis of other oligo (phosphole) s and the elucidation of their photo-physical and electrochemical properties are still needed in order to establish reliable structure-property relationships. 

Similar couplings of hexabromobenzene 98 with TMSA proceeds easily under nonnal conditions to afford the completely sixfold-coupled product followed by desilylation with KOH to give hexaethynylbenzene 99 in 28% yields [Eq. (37)] [55]. 1,2,4,5-Tetraiodobenzene 100 also undergoes tetrasubstitution to give 1,2,4,5-tetraethynylbenzene 101 after desilylation. This product is converted into linear oligo(biphenylene) 103 [Eq. (38)] [56]. 

Up to now, the main interest in electroreductive coupling of dichlorosilanes was the formation of linear oligo- and polysilanes [2]. But, as shown in our previous work [3], cyclic electrolysis products are not uncommon. Thus, we tested the applicability of electroreductive coupling for the specific formation of cyclotetra-, -penta-, and -hexasilanes. 

This sequence applied to the synthesis of a linear tetramer provides a general access to a wide range of linear oligo- and polymeric pyridinium compounds and represents an useful alternative to the Zincke procedure proposed by Kaiser et al. [41]. 

Structural assignments and purity determination of the macrocyclic and/or linear oligo- and polymeric pyridinium compounds represent a peculiar aspect in the study of these compounds, due to the presence of a repetitive alkylpyridinium subunit in their polycationic structure. 

A variety of linear oligo- and polysaccharides can be also prepared using glycosyltransferases of the non-Leloir pathway, which utilize sugar z-phosphates as... 

In order to examine the ionophoric activities of crownophanes, their extraction of solid alkali metal thiocyanates into CHjClj was carried out. As shown in Table 2, crownophanes 34 (s. Scheme 1) efficiently and selectively extracted LiSCN under anhydrous conditions. The linear oligo(oxyethylene) compounds also extracted the salt sufficiently. Their alkali metal affinity seems to result in... 

Soon after the above study was published, research by Rulkens et al on linear oligo(ferro-cenyldimethylsilanes) gave a somewhat different experimental result. Odd-number N oligo(ferro-cenyldimethylsilanes) showed only two peaks while even-numbered N>2 showed three peaks. The redox behavior of these oligo(ferrocenyldimethylsilanes) is illustrated in Figure 4. 

Samadi, F. Eckelt, J. Wolf, B. A. Schule, H. Frey, H., Branched Versus Linear Oligo(dimethylsiloxanes) Differences in Their Thermodynamic Interaction with Solvents. J. Polym. Sci., PartB Polym. Phys. 2010, 48,1308-1318. 

The substitution of polythiophene films by linear oligo(o3qrethy-lene) chains has been largely used to obtain materials that are not only endowed complexing properties toward cations, but also soluble, with a highly hydrophilic character [11]. 

Rulkens, R., A. J. Lough, I. Manners, S. R. Lovelace, C. Grant, and W. E. Geiger. 1996. Linear oligo(ferrocenyldimelhylsilanes) with between two and nine ferrocene units electrochemical and structural models for poly(ferrocenylsilane) high polymers, journal of the American Chemical Society 118 (50) 12683-12695. 

Bruna S, Gonzalez-Vadillo AM, Nieto D, Pastor CJ, Cuadrado I (2012) Redox-active macrocyclic and linear oligo-carbosiloxanes prepared via hydrosilylation from 1,3-divinyl-l,3-dimethyl-l,3-diferrocenyldisiloxane. Macromolecules 45 781-793... 

Linear Oligo(esters) of p-(P-HYDROXY)-ETHOXYBENZOIC Acid HPCH2CH2O—CO] OR ... 

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