Groups spacer

Elbert R, Laschewsky A and Ringsdorf H 1985 Hydrophilic spacer groups in polymerizable lipids— formation of biomembrane models from bulk polymerized lipids J. Am. Ohem. Soc. 107 4134-41... 

Schneider J, Erdelen C, Ringsdorf H and Rabolt J F 1989 Structural studies of polymers with hydrophilic spacer groups. 2. Infrared-spectroscopy of Langmuir-Blodgett multilayers of polymers with fluorocarbon side-chains at ambient and elevated temperatures Macromolecules 22 3475-80... 

Aromatic perfluoroaLkylation can be effected by fluorinated aUphatics via different techniques. One category features copper-assisted coupling of aryl hahdes with perfluoroalkyl iodides (eg, CF I) (111,112) or difluoromethane derivatives such as CF2Br2 (Burton s reagent) (113,114), as well as electrochemical trifluoromethylation using CF Br with a sacrificial copper anode (115). Extmsion of spacer groups attached to the fluoroalkyl moiety, eg,... 

LB Films of Polymeric Amphiphile. Since the first successful deposition of a polymeric LB film (61), there have been a large number of studies examining different stmctural parameters on the transferabiHty and stabiHty of the polymeric LB films (4). One interesting idea for polymers for LB films is the use of a spacer group (mosdy hydrophilic) to decouple the motion of the polymer from that of the Hpid membrane (62,63). Monolayers from a poljmier (10) having hydrophilic phosphate groups and a tetraethylene oxide spacer were used to link a glycerol diether to the polymer chain (63). 

Hydrophilic spacer groups may be introduced into a polymer through the side chain, the main chain, or both. Films can be prepared using different values of monomer feed (62). 

In the pendent chain systems, the dmg is chemically bound to a polymer backbone and is released by hydrolytic or enzymatic cleavage of the chemical bond. The dmg may be attached directiy to the polymer or may be linked via a spacer group. The spacer group may be used to affect the rate of dmg release and the hydrophilicity of the system. These systems allow very high dmg loadings (over 80 wt %) (89) which decrease the cost of the polymeric materials used ia the systems. These systems have beea examiaed by many iavestigators (111,112). 

When additional substituents are introduced in the 2- and/or 4-position, the thermal rearrangement gives products in which the substituents that were originally located in the 1- and 5-position of the quadricyclane are then located at C4 and C5 of the oxepin 7.30,123 In order to trap intermediates of this rearrangement reaction by intramolecular cycloaddition vinyl and acetylene groups were linked with different spacer groups to C2 of quadricyclane.123 In this manner two different intramolecular cycloadducts were isolated in addition to oxepin derivatives.123... 

Liquid crystalline main chain polymers with siloxane spacer groups were obtained by the hydrosilation of (Si—H) terminated polydimethylsiloxane oligomers and mesogenic groups with terminal double bonds as shown in Reaction Scheme XVII-(a). Reactions were usually carried out in THF with the Wacker Oil catalyst 255). Completion of the reactions was followed by the disappearance of the strong (Si—H) absorption band at 2140 cm-1 using IR spectroscopy. 

Polyphosphazenes bearing crown ethers (12-crown-4,15-crown-5 and 18-crown-6) as single or as mixed substituents with trifluoroethoxy or methoxy-ethoxyethoxy groups were synthesized by Cowie [601,602] and Allcock [484] and their conductivity studied because it was shown that the incorporation of crown ether molecules into a polymer electrolyte could increase their ionic conductivity. In these macromolecules, the crown ether units were linked to the backbone through oxymethylene spacer groups. 

Effects of spacer groups on the formation and properties of the mixed-valence states of conjugated ferrocene dimers have been extensively studied by both electrochemical and spectroscopic methods. It should be noted that a characteristic feature in the electronic spectra of ferrocene dimers with conjugated spacer groups is the appearance of metal-to-ligand charge transfer (MLCT) bands in the neutral form as well as IT bands in the mixed-valence state. The dimer Fc — CH=CH — Fc... 

When the metalloporphyrin bears a donor group on its periphery, it can behave as a self-complementary ditopic unit capable of metal-ligand induced dimerization. Many systems have been synthesized using different metals, ligands, and spacers. The length and geometry of the spacer groups determine the stoichiometry of the assembly process. 

The DSC spectra confirm that the fluid phase of the polymerized vesicles remains and the phase transitions are retained with the introduction of the spacer group. As can been seen in Figure 8 of the DSC spectrum of the monomeric lipid, there is a peak around 28°C which corresponds to the phase transition of monomeric lipid. As the result of the presence of the spacer group, a similar phase transition can also be observed clearly in the spectrum of the polymerized lipid as shown in Figure 9, but the transition temperature is increased to 36°C by the presence of the polymer chains. 

In this paper two new polymerized vesicle systems have been presented. The first lipid can be polymerized in vesicle through UV irradiation. Because the second lipid contains a flexible spacer group it can be prepolymerized in benzene and then converted to vesicles by ultrasonication in water. The polymerization improves the stabilities of the synthetic liposomes. Since there is a acetal linkage between the... 

A number of bis(tacn) ligands, composed of pairs of covalently linked tacn macrocycles, can form similar structures, provided the linker group between the sandwiching macrocycles is sufficiently flexible (e.g., (556)).1411-1413 In particular, several Ni11 complexes of poly(tacn) derivatives with a central benzene have been studied, where the Ni is sandwiched between pairs of tacn macrocycles when these are attached to the ortho positions of the aromatic spacer group (e.g., (557)).1412,1413... 

It was our decision to combine two diacid units with a diamine as shown in Eq. (1) that gave the solution to the problem. The diamine acts. as a spacer group that converts two U-shaped subunits into a C-shaped molecule 6 which now involves a near perfect focus of two carboxyl groups. Enforcing this shape, rather than the S-shape 7 which is also possible can be accomplished by further remote structural elements. 

The aromatic spacer group of the model receptors prevent the formation of intramolecular hydrogen bonds between the opposing carboxyls yet these functions are ideally positioned for intermolecular hydrogen bonds of the sort indicated in 32. The acridine derivatives do indeed form stoichiometric complexes with oxalic, malonic (and C-substituted malonic acids) as well as maleic and phthalic acids, Fumaric, succinic or glutaric acids did not form such complexes. Though protonation appears to be a necessary element in the recognition of these diacids, the receptor has more to... 

Bridged squaraine labels such as 34 that absorb at 632 nm (eM = 250,000 M 1cm" ) and emit at 646 nm in PBS are reported in a patent [22]. A similar approach but linking the spacer in the 3-position of one indolenine with the spacer group attached to the indolenine-nitrogen in the second heterocycle was proposed in [23, 24],... 

Our results show that the network density (vg - 1/Q Q = swelling degree) of the crosslinked polymers is a function of the light intensity, the exposure time, the acrylate content, the molecular weight of the uncrosslinked silicone, and also of the length of the spacer group between the acrylate or methacrylate unit and the silicone backbone. Oxygen influences only the polymerization kinetics, but it does not influence the network density. 

SIACX, or succinimidyl-6-((((4-(iodoacetyl)amino)methyl)cyclohexane-l-carbonyl)amino) hexanoate, is an analog of SIAC that contains an additional aminohexanoate spacer group next to its NHS ester end (Invitrogen). The result is the creation of an approximately 16-atom spacer arm between conjugated molecules. All other properties of SIACX are similar to SIAC. 

Figure 11.1 The basic design of a biotinylation reagent includes the bicyclic rings and valeric acid side chain of D-biotin at one end and a reactive group to couple with target groups at the other end. Spacer groups may be included in the design to extend the biotin group away from modified molecules, thus ensuring better interaction capability with avidin or streptavidin probes.

The only disadvantage to the use of NHS-biotin or sulfo-NHS-biotin is the lack of a long spacer group off the valeric acid side chain. Since the binding site for biotin on avidin and streptavidin is somewhat below the surface of the proteins, some biotinylated molecules may not interact as efficiently with (strept)avidin as when longer cross-bridges are used (Green et al., 1971 Bonnard et al., 1984). 

The Derivative, 5-(biotinamido)pentylamine, contains a 5-carbon cadaverine spacer group attached to the valeric acid side chain of biotin (Thermo Fisher). The compound can be used in a carbodi-imide reaction process to label carboxylate groups in proteins and other molecules, forming amide bond linkages (Chapter 3, Section 1). However, the main use of this biotinylation reagent is in the determination of factor XHIa or transglutaminase enzymes in plasma, cell, or tissue extracts. 

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