Anchoring moiety

Biphenyl mesogens with R=CN [(4 -cyanobiphenyl-4-yl-)oxy-] or R=OCH3 [(4 -methoxybiphenyl-4-yl)-oxy-] were attached to norborn-2-ene moieties, and separated by different spacer lengths and carboxylic acid ester, ether or imido-groups as anchoring moieties, as shown in Fig. 4. 

Diblock copolymers A-N immersed in a homopolymer P matrix segregate to its interfaces. One of the copolymer blocks ( anchor moiety A) selectively attaches to the interface while the other ( buoy block N) dangles out to form a brush like layer, providing a simple means for the realization of polymer brushes (see Fig. 33). 

Fig, 33.a Schematic illustration of N-mer brush layer created by diblock copolymers A-N attached selectively to the interface by their anchor moiety A. Copolymers in the brush layer are in equilibrium with free diblocks incorporated in the bulk region of the sample abundant in homopolymer P. b The form of the diblock volume fraction vs depth ( )(z) profile used in theoretical model, c Potential U(z) affecting the anchor moiety A and driving the diblock segregation... 

The full relation for the chemical potential of the copolymers in the bulk Pbmsh can be obtained from the Flory-Huggins energy of mixing between diblock copolymers A-N and homopolymers P [259, 260], when interaction parameters %AP> %AN, and % (% =%np) are specified. In most experiments brush N-mers and homopolymer P-mers are microstructurally identical and differ only in the isotopic status. Related isotopic interaction parameter % is usually much smaller than parameters yAP and %AN. Assuming [254] Xan=X,m<+X, and neglecting volume fraction of the anchor moieties in the bulk, the expression for pbulk is obtained in the form... 

An additional factor driving the segregation exists whenever the anchoring moieties change interactions at the interface. The related reduction A in brush chain free energy may depend on the molecular architecture of diblocks (i.e.,the size of blocks and of copolymer) as was recognized by our recent studies [254] described in Sect. 4.2.3. The results of these studies are analyzed with mean field and self consistent mean field approaches, both yielding identical adsorption parameters. 

On the basis of the structural requirements for an efficient modifier, and using the above model as a working hypothesis, several new modifiers have been developed (Fig. 3) [6,29,30], These studies revealed that (i) only extended flat aromatic ring systems (the naphthyl, quinolyl, anthracenyl groups in 1-3) are efficient anchoring moieties, whereas phenyl or pyridyl rings in 4 or the non-flat triptycenyl moiety in 5 are not suitable for adsorption parallel to the metal surface, and (ii) the N-heteroatom in the aromatic ring system (2) is not a necessary requirement for adsorption of the modifier and enantio-differentiation. 

To successfully perform Y3H screens, the choice of the anchor moiety of the hybrid ligand is important. MTX, as already indicated, shows much promise. It exhibits high affinity (low nanomolar to picomolar) for the monomeric form of E. coli dihydrofolate reductase (eDHFR), which is a small, compact molecule that can be easily expressed as a fusion protein in yeast cells [46], Furthermore, contrary to what is often observed with nonhybrid small molecules, MTX-hybrid molecules appear to generally permeate yeast cells quite readily. At GPC Biotech we have screened over 50 hybrid ligands in which MTX was coupled to various small molecule chemotypes. To date we have not encountered difficulties with cellular uptake of these molecules. Cellular uptake can readily be determined using appropriate competition experiments, as outlined in Fig. 18.2-5. 

Anchoring group, linker, a group bound to the polymeric support for the attachment of the first amino add in polymer-supported peptide synthesis. The chloromethyl group was the first anchoring moiety in the polystyrene/divinylbenzene resin for solid-phase peptide synthesis devdoped by Bruce Merrifield [R. B. Merrifield, J. Am. Chem. Soc. 1963, 85, 2149]. 

Computational studies predict that application of anchoring moieties with higher electron-accepting properties should result in DSSC performance higher than that of carboxylic-anchored MPs of the same structure [25]. This prediction found its experimental confirmation [26-28]. 

Scheme 17 General stmctural formulas of the 3AB- and 2AB-type mero-substituted MPs. M is 2H, Zn, or other metal. A is the anchoring moiety (-COOH, -SO3H, -PO3H, or other) of an anchoring group. An aryl, ethylene, etc., spacer may be introduced between the anchoring group and the MP macrocycle. The most common B is the aryl substituent...

Scheme 19 Structural formulas of the A3B-type porphyrins used for examination of the effect of the position of the anchoring carboxyUc group on the DSSC performance. The anchoring moiety located in the a para-, b meta-, and c ortho-position used in Ref. [28]...

Following successfid push-pull porphyrin design for application in DSSCs, a study focused on enhancement of the pull properties of the anchoring moiety of... 

Similar to the acene-modified anchoring moiety (Scheme 25) for ji-conjugated D moieties [46], the effect of polycychc aromatic spacer of the D or A moiety on the absorbance of ZnP dyes and the DSSC performance with these MPs were extensively studied (Scheme 42) [69, 70, 72, 77]. 

Scheme 46 Stmctural formulas of the push-pull YD2 and YD2-o-C8-type Zn porphyrins with the modified anchoring moiety A used in Ref [90]...

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