Diverse property-derived method

DPD method = Diverse Property-Derived method —> cell-based methods... 

The Diverse Property-Derived method (DPD method) is based on the partitioning of six noncorrelated molecular descriptors and physico-chemical properties [Ashton, Jaye et al, 1996]. These are a lipophilicity descriptor (CLOGP), an electrotopological index calculated as normalized sum of the squares of the atomic electrotopological state indices, the number of hydrogen-bond acceptors (HBA), the number of hydrogen-bond donors (HBD), a flexibility index defined as the ratio of the —> Kier shape descriptors over k, and the aromatic density defined as the number of aromatic rings over the molecular volume (Table Cl). 

The present article is an attempt to review those studies of pyridinelike heterocycles (mono-azines) and, to a lesser extent, their analogues and derivatives that have interpreted the behavior and estimated various physico-chemical properties of the compounds by the use of data calculated by the simplest version of the MO LCAO (molecular orbital, linear combination of atomic orbitals) method (both molecular orbital energies and expansion coefficients). In this review, attention is focused upon the use of the simple method because it has been applied to quite extensive sets of compounds and to the calculation of the most diverse properties. On the other hand, many fewer compounds and physico-chemical properties have been investigated by the more sophisticated methods. Such studies are referred to without being discussed in detail. In a couple of years, we believe, the extent of the applications of such methods will also be wide enough to warrant a detailed review. 

Before anything else can be said about IEs, some rudimentary chemistry is needed. From a cookbook perspective, all explosives (be they military, commercial, or improvised) require the same chemical building blocks, which consist of a fuel and an oxidizer. Some explosives have the fuel and oxidizer as part of the same molecule, such as trinitrotoluene (TNT), and some explosives are comprised of mixtures of separate fuels and oxidizers, such as ammonium nitrate-fuel oil (ANFO). The oxidizer employed by the vast majority of explosives tends to be the NO2 (nitro) group. It is so predominant as an explosive ingredient that the primary focus of detection methods traditionally has been to look for nitro-derived properties. IEs tend to utilize a more diverse range of oxidizers. Table 3.1 gives a list of the numerous oxidizer possibilities. 

Methods based on molecular properties attempt to avoid the drawbacks of the fragmental methods, such as their failure to calculate log P for structures with missing fragments. However, in some cases, models were derived from sets of compounds with moderate chemical diversity limiting the accuracy of predicted log P. 

---