Heptazine

A heptazine, or tri-s-triazine or cyamelurine, is a type of chemical compound that consist of a planar triangular core group, C6N7, or three fused triazine rings, with three substituents at the corners of the triangle.
The general form is 1,3,4,6,7,9,9b-heptaazaphenalene. The parent compound C6N7H3, where the three substituents are hydrogens, is called 1,3,4,6,7,9-hexaazacyc1[3.3.3]azine or tri-s-triazine proper.