Synthesis and Structure of 2,5,8-Triazido-s-Heptazine:  An Energetic and Luminescent Precursor to Nitrogen-Rich Carbon Nitrides

• Published in: Journal of the American Chemical Society Vol. 126; no. 17; pp. 5372 - 5373
• Main Authors: Miller, Dale R, Swenson, Dale C, Gillan, Edward G
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 05.05.2004
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Heterocyclic compounds; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Organic compounds; Photoluminescence; Physics; Solid organic materials; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Molecular structure; Nitrogen heterocycle; Photoluminescence; Luminescence spectrometry; Tricyclic compound; Experimental study; Organic compounds; Ultraviolet visible spectrometry; Crystal structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja048939y

Derivatized s-triazine (C3N3) precursors have seen significant recent use in the production of carbon nitride materials. Larger polycyclic molecular precursors, such as those containing an s-heptazine core (C6N7 or tri-s-triazine), may improve stability and order in carbon nitride products. In this Communication, we describe the synthesis and crystal structure of 2,5,8-triazido-s-heptazine (2). Synthesis of 2 was achieved from melon, an oligomeric s-heptazine synthesized by the pyrolysis of NH4SCN. Melon was converted to molecular 2,5,8-trichloro-s-heptazine, which was then transformed to the triazide upon reaction with (CH3)3SiN3. The crystal structure of 2 verifies that the s-heptazine is planar and the azides adopt a pinwheel-like C 3h arrangement around the periphery. The s-heptazine core shows π delocalization in the C−N bonds around the periphery (av. 1.33 Å), while the internal planar C−N bonds are longer (1.40 Å). The heptazine units pack into parallel, but offset, layered sheets in the crystal. The triazide 2 exhibits photoluminescence at 430 nm and rapidly and exothermically decomposes upon heating at 185 °C to produce a tan thermally stable carbon nitride powder with a formula near C3N4.