Structure-density relationship molecular descriptors

Other pharmacological activities have also been correlated with quantum-chemically derived descriptors. For instance, the quantitative structure-activity relationship developed for the antibacterial activity of a series of monocyclic (i-lactam antibiotics included the atomic charges, the bond orders, the dipole moment, and the first excitation energy of the compound [103]. The fungicidal activity of A3-l,2,4-thiadiazolines has been correlated with an index of frontier orbital electron density derived from semi-empirical PM3 molecular orbital calculations [104],... 

The alternatives to mathematical descriptors derived from molecular graphs or molecular geometry are the traditional QSAR (quantitative structure-activity relationship) descriptors and quantum chemically computed parameters. The former include the partition coefficient for oil/water (often octanol/water) (log P), the Hammet sigma value (electronic parameter that measures the electron withdrawal from and the electron release to the aromatic ring by a substituent, the Taft s parameters for the electronic effects of substituents in aliphatic compounds (a ), and a steric parameter for the proximity of substituents on reaction sites (Es)- Also selected molecular properties, such as molar refractivity (MR), polarizability (a), molecular weight (MW), and density (d), have been used. 

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