Structure-selectivity relationship

Structure-Selectivity Relationship in Xylene Isomerization and Selective Toluene Disproportionation... 

I would like to emphasize the simplicity of Simon s molecules more than I did in my previous comment. These are by far the simplest class of ion-selective molecules that act in bilayers and they open up very promising prospects for the study and understanding of structure-selectivity relationships. 

Early on, it was anticipated that many repetitive calibrations and EMF measurements would be carried out in the evaluation of a large quantity of electrodes. The first microcomputer-based automated titration system utilizing high level software (CONVERS) hastened these studies (10), as did a more recently constructed minicomputer system (Figure 1). Typical results are shown in Figure 2, where a set of five protriptyline CWEs were calibrated simultaneously (11). Graphic side-by-side comparison of different electrode calibrations was also useful in establishing structure-selectivity relationships. 

Sutherland, J., Weaver, D.F. Three-dimensional Quantitative Structure-Activity and Structure-Selectivity Relationships of Dihydrofolate Reductase Inhibitors./. Comput.-Aided Mol. Des. 2004, 18, 309-331. 

These examples and many others have provided evidence of significant changes in catalyst structures resulting from changes in operating conditions. Techniques are thus necessary that can be applied to catalysts in the presence of probe molecules, in reactive environments (e.g., when catalysts undergo reduction, oxidation, etc.), and under catalytic reaction conditions. Moreover, the simultaneous determination of catalyst structure and activity or selectivity is needed to establish structure-activity or structure-selectivity relationships, which provide a basis for improvement and development of catalysts (Banares, 2005 Thomas, 1980 Thomas, 1999 Topsoe, 2000 Wachs, 2005). The need for characterization of catalysts during... 

In a study of non-peptide inhibitors of the measles virus entry the findings from the MFTA model were also consistent with the 3D molecular model of the binding site of virus fusion protein. In addition, they suggest the structural modifications to improve the activity. Similar results were obtained in a study of structure-activity and structure-selectivity relationships for anticholinesterase O-phosphorylated oximes. ... 

Sutherland, J.J. and Weaver, D.F. (2004) Three-dimensional quantitative structure-activity and structure-selectivity relationships of dihydrofolate reductase inhibitors. J. Comput. Aid. Mol. Des., 18, 309-331. 

Itoh Y et al (2007) Design, synthesis, structure-selectivity relationship, and effect on human cancer cells of a novel series of histone deacetylase 6-selective inhibitors. J Med Chem 50(22) 5425-5438... 

Finally, in case of the GABA-antagonistic sesquiterpenoids treated in the last section, interesting new insights into the structure-activity- and especially structure-selectivity relationships were introduced. Recently discovered selective toxicity towards insects as well as helminths point towards the potential of such compounds as leads to new insecticides and antiparasitic drugs. 

It is important to state that there is no evidence that the Zimmerman-Traxler model represents the actual transition state for aldol-like reactions. Nonetheless, this model is a useful mnemonic, extensively used and makes reasonable predictions in many cases. It is used to predict structure-selectivity relationships for lithium. 

Figure 11.8 Different structure-selectivity relationships. Structurally similar as well as diverse molecules display different selectivity patterns in a set of cathepsin enzyme inhibitors. SR means selectivity ratio and is calculated as the quotient of the...

Peltason L, Hu Y, Bajorath J. From structure-activity to structure-selectivity relationships Quantitative assessment, selectivity cliffs, and key compounds. ChemMedChem 2009 4 1864-1873. 

Some trends were observed in the catalysis. The reactivity of 75 follows the order ob>d a, while the diastereoselectivity towards C2-76 is similar, Ob d>a. No direct structure/selectivity relationship is evident among the benzyl halides, although as expected bromides react faster than chlorides. 

An effective, practical and readily available chiral modifier was developed for the effective enantioselective cyclopropanation of several allylic alcohols using bis(iodomethyl)zinc. Several chemical modifications have revealed a unique cooperativity between the boron acidic center and the basic amide groups. These observations and a better understanding of the structure/selectivity relationship of the chiral additive should lead to an improved cyclopropanation system. 

In contrast, SEIRA spectra display more intense bands corresponding to the more polar groups existing in the calixarene host molecule, while only a weak PYR band is observed at 840 cm". Thus, SEIRA seems to be more appropriate to follow structural changes occurring in the host due to the adsorption and the complexation with the analyte and to find a structure/selectivity relationship. 

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