Exploration for the Optical Properties and Fluorescent Prediction of Nitrotriazole and Nitrofurazan: First-Principles and TD-DFT Calculations.

High-energy materials containing azole and furazan have revealed numerous properties; however, the underlying optical properties need to be solved. Meanwhile, the uncertainty for the choice of fluorescent matrix materials and the flexible situational conditions prompted us to estimate the optical and fluorescent properties of 5,5'-dinitro-2,2'-3,3'-bi-1,2,4-triazole (), 4,4'-dinitroazolefurazan (), and 4,4'-dinitro-3,3'-4,3'-ter-1,2,5-oxadiazole (). The first-principles calculation with improved dispersion correction terms and time-dependent density functional theory were utilized to calculate the absorbance and excitation energy of , , and , as well as characterization for their crystal structure, electronic structure, molecular orbitals, and so forth, synchronously. In this work, the absorbance anisotropy of and is stronger than that of . The absorbance for each of the (0,0,1) crystal planes in the three compounds is greater than that of the other two crystal planes. Moreover, has the maximum absorbance on the (0,0,1) crystal plane. The N-N-H from and N-O-N from and are responsible for these results, while N=N in weakens the performance of N-O-N. UV-vis spectra show that the maximum absorption wavelengths λ for , , and are 225, 228, and 201 nm, respectively. The number of five-membered rings and the coplanarity of groups in the intermolecular non-conjugation interaction potentially improve this ability due to the results from the crystal diffraction analysis. In addition, the polarization rate > > based on the molecular orbital analysis and the electrostatic potential calculation implies that the excitation energy of is less than , and the excitation energy of is less than . This work is beneficial to the expansion of energetic materials into the optical field and the accelerated application process of the related industry.