Reliable prediction of crystal density of high nitrogen-containing organic compounds as powerful, less sensitive, eco-friendly energetic materials for dependable assessment of their performance

Abstract

Many efforts have been done in recent years to seek more powerful, less sensitive, eco-friendly high nitrogen-containing organic compounds (HNCOCs). It is essential to have reliable methods for the prediction of crystal density of the new proposed HNCOCs because increasing density is associated with increased performance. This work uses structural parameters of HNCOCs and semiempirical quantum mechanical calculations using the PM6 method for reliable prediction of their densities at or near room temperature. A core correlation is introduced for the calculation of the density of HNCOCs based on the number of functional groups –NH2, >NH, –OH, and –N3 as well as the calculated density from the PM6 method. The reliability of the core correlation is improved by considering two non-additive correcting functions, which can increase or decrease the predicted values of core density. The reported densities of 137 HNCOCs as training (117 compounds) and test (20 chemicals) sets are used to establish the new model. High reliability of the core and improved models are compared with the computed results of the best available molecular surface electrostatic potential (MESP)-based method. The values of Root Mean Square Error (RMSE) for the improved model and comparative MESP-based method are 0.0472 and 0.0951 g/cm3, respectively. High reliability of the new method was also confirmed as compared to four MESP-based models for 32 compounds of external test data set where RMSE of the improved model (0.0674 g/cm3) is smaller than four MSPE-based methods, i.e. 0.126, 0.276, 0.0716, and 0.0703 g/cm3.