Spacer groups alkyl

Figure 13.1 The general structure of a silane coupling agent includes a functional group or reactive group at the end of an organic spacer This alkyl chain is attached to the central silicon atom, which also has up to three hydrolysable groups attached to it.

Table 3 Kinetic Parameters for Back Electron Transfer from Colloidal SnC>2 to Several Dyes Featuring Peripheral Alkyl Spacer Groups...

QAS QAS with ether spacer group between quaternary N atom and long alkyl tail Goldschmidt (Milbum and Sitz, 2002)... 

Beside the conventional surfactants with one polar head group and one nonpolar tail, dimeric and oligomeric surfactants have attracted considerable interest in academia and industry [521], Dimeric surfactants, also called Gemini surfactants, are made up of two amphiphilic moieties connected closely to the head group by a spacer group (Fig. 12.1). In bolaform surfactants the connection is in the middle of the alkyl chain or close to the end, so that they can be considered as two polar head groups connected by a long hydrophobic chain. 

Materials and Film Preparation. The molecular structure of the polymerized lipid referred to as CO-1.5 is shown in Figure 1. The material is a co-polymer of a double 18-carbon alkyl chain lipid with a side-group spacer and five main-chain spacer groups. The purpose of the spacer chains is to allow more free volume for the lipid chains to orientationally order normal to the polymer backbone. The lipid chain contains an amide, and the main-chain spacer groups contain tertiary amines. The polymer was synthesized following the general procedures given by Laschewsky et al. (10). 

Organosilicones are favourable in a broad variety of industrial applications primarily because of their unique smface active properties. Especially in the case of aqueous applications the hydrophilically substituted trisiloxane derivatives are good wetting agents. Usually, the molecule consists of a lyophobic trisiloxane moiety attached directly to an alkyl spacer group via a silicon-carbon bond. This spacer group carries on the other side a nonionic or an ionic hydrophilic part. 

Semi-flexible bipyridine derivatives incorporating alkyl spacer groups between the pyridyl rings have been demonstrated to yield dinuclear palladium(II) species related to those discussed in Section 7.2 of this chapter.Thus, insertion of -CHjCHj- or -CH2(CgF4)CH2- groups between the 4- and 4 -positions in the parent bipyridine ligand leads to the formation of 2 2 (metal ligand) complexes of type 32 on reaction of these extended bipyridine derivatives with dinitro(ethane-... 

In general, these organomodified trisiloxanes are based on a common structural principle They consist of a lyophobic silicone backbone containing an alkyl spacer group connected by a silicon-carbon bond. The hydrophilic moiety, which can be either ionic or nonionic, is attached to the alkyl spacer... 

In addition to the chromatographic supports already described, many other supports are available (both silica-based and organic polymer-based) that exhibit very different properties. The silica-based supports compnse those in which the surface silanol groups are bonded with a short-chain alkyl spacer group that terminates with one or more functional groups or a cyclohexyl or phenyl ring (see Table 2). Such supports can be very useful for preparative work, e.g., the use ofy-aminopropyl bonded silica columns for the isolation of polar materials such as carbohydrates. 

---