A 16 indole unit protoparticle for DHI-melanin is suggested. The porphyrin-like structure gives account of some melanin s properties. The interstellar spaces particles can be blacks derived from one or more heterocyclic systems like indicated in the table 1. Black materials can also be obtained by synthesis like, for example, pyrroleblack.
Melanins constitute an insoluble and infusible material difficult to purify.
For this reason, almost all the experimental material collected in the melanins chemical and physical study is difficult to interpret. Melanins could have origin from different molecules called melanogens. It is curious that in the Little's model the spine was acetyleneblack and the lateral chains were constituted by diethylcyanine iodide, a well known light-sensitive compound. DHI units are represented in the tables 2 and 3. The second phase of polymerization is characterized by self-assembling of the different units up to achieve graphite structures of the type shown in the table 4.