Tailored molecular similarity

Basak SC, Gute BD, Mills D, Hawkins DM. Quantitative molecular similarity methods in the property/toxicity estimation of chemicals a comparison of arbitrary versus tailored similarity spaces. J Mol Struct (Theochem) 2003 622 127-45. 

Alumipophosphate molecular sieve membranes. In addition to zeolites, Haag Tsikoyiannis [1991] have also briefly described another type of molecular sieve membranes consisting of AIPO4 units whose aluminum or phosphorous constituent may be substituted by other elements such as silicon or metals. These membranes are made from aluminophosphates, silico-aluminophosphates, metalo-aluminophosphates or metalo-aluminophosphosilicates. Like zeolites, these materials have ordered pore structures that can discriminate molecules based on their molecular dimensions. Their separation and catalytic properties can also be tailored with similar techniques employed for zeolites. The procedures for calcining the membranes or separating them from non-porous subsuates are essentially the same as those described earlier for zeolites. 

In this chapter, we will discuss the utihty of HiQSAR studies using these five classes of descriptors. We will also show the utility of molecular similarity and our recently developed tailored similarity approach in the clustering of chemical libraries and selection of analogs. 

In drug design, one uses the molecular similarity concept to select analogs of interesting leads. Such selections are usually made based on user-defined methods. Therefore, such methods are always biased. We have come up with the idea of tailored similarity , where the property of interest is used to create a structure space that is relevant to that specific property. The results indicate that such tailored methods outperform arbitrary, user-defined QMSA techniques. 

Molecular orientation results in increased stiffness, strength, and toughness (Table 8-12) as well as resistance to liquid and gas permeation, crazing, microcracks, and others in the direction or plane of the orientation. The orientation of fibers in reinforced plastics causes similar positive influences. Orientation in effect provides a means of tailoring and improving the properties of plastics. 

Similar materials, hyperbranched polyesters based on bis-MPA and a polyol are now commercially available [11] from Perstorp AB under the trade name Boltorn [12], Figure 8.1. The average number of hydroxyl groups per molecule can be tailored between 8 and 64 and molecular weight can be varied between c. 2000 and 11 000. The co-polymerization of bis-MPA and a polyol core keeps the molecular weight distribution fairly low, typically below 2. 

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