Spacer length, influence

It has to be taken into account that these catalysts are not yet fully developed. Introduction of electron-withdrawing groups is suspected to increase Lewis acidity, which influences activity, and the optimum spacer length may enable formation of chiral polymers, but such variations are synthetically challenging. 

Ma ZF, Li JR, Jiang L, Cao J, Boullanger P. Influence of the spacer length of glycolipid receptors in polydiacetylene vesicles on the colorimetric detection of Escherichia coli. Langmuir 2000 16 7801-7804. 

These measurements clearly confirm the consideration that the length of the flexible spacer directly influences the elastic constants. This could also be obtained by other authors 69>. 

Mendoza-Ferri M-G, Hartinger CG, Eichinger RE, Stolyarova N, Severin K, Jakupec MA, Nazarov AA, Keppler BK (2008) Influence of the spacer length on the in vitro anticancer activity of dinuclear ruthenium-arene compounds. Organometallics 27 2405-2407... 

Our group investigated the influence of the spacer length of 2,3-disubsti-tuted norbornene derivatives with cyanobiphenyl-mesogenic units [42] and with methoxybiphenyl-mesogenic units [43] on the mesophases. Exo,endo-his-[(4 -cyanobiphenyl-4-yl)oxy-n-alkyl]norborn-5-ene-2,3-dicarboxylates with different alkyl spacer lengths (IV-n, n=2-12) were synthesized in a straightforward manner. 

In this chapter we want to discuss the correlation of the mesophase behavior of a cyanobiphenyl-based SCLCP with its backbone structure. As shown before, the backbone structure, the spacer lengths, and the mesogen density per repeat unit have great influence on the LC mesophase evolved. Ligure 8 shows some examples of backbone structures bearing the cyanobiphenyl-moiety that have been reported in literature. The above-mentioned ROMP-derived polymers poly-(II-n) [39],poly-(IV-n) [42,47],poly-(VI-n) [41],andpoly-(VII-n) [53] will be compared with each other and with acrylate-based [56-59], siloxane-based [60] and vinylcyclopropane-based systems [61]. The detected mesophases and their transition temperatures are summarized in Table 6. 

Originally the work with spacer arms assumed that the spacer worked purely passively to remove the ligand from the microenvironment and/or the steric effects associated with the matrix backbone [44, 49]. Observations that a minimum spacer length [44,45,49] was required for acquisition of activity by the ligand were interpreted as being due to the arm being too short to remove the ligand from the influence of the matrix. 

Influence of chain length and spacer length on Tg, on the heat capacity increment at Tg (ACp), and the shape of the Cp(T) curve win be presented in the first paper (preliminary results can be found in (3)). Subsequently, we will address influence of thermal history in the isotropic phase and N+I biphase, physical aging below Tg and Tg in blends of LCPs. Finally, an interpretation of the macroscopic data in terms of molecular organization in these and other nematic LCP glasses will be attempted. 

Engel A, Chatter) ee SK, Alarifi A, Riemann D, Langner J, Nuhn P (2003) Influence of spacer length on interaction of mannosylated liposomes with human phagocytic cells. Pharm Res 20 51-57... 

Similarly, OS supported iodide can be used with the same success. For example, using only 100 ppm of Pd(OAc)2 as catalyst, it has been possible to perform the Heck reaction between a supported 4-iodobenzoic ester and /ert-butylacrylate. All parameters were evaluated in this reaction, and the overall message is that every parameter has a noticeable influence on the outcome of the reaction, including spacer length, nature of the counter anion, nature of the IL matrix, and nature of the base [18, 20], In all cases, disubstituted olefins could be isolated by transesterification of the benzoate support under basic (NH3/MeOH) or acidic (HCl/MeOH) conditions. 

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