On the molecular structure that produces the phosphorescence of 7-azaindole. 1. The case of 2-tert-butyl-7-azaindole

If the structured phosphorescence with a 0–0 component at ca. 430 nm exhibited by 7-azaindole is due to a molecular structure resulting from an interaction between a double hydrogen bonding dimer and a polar molecule (7-azaindole itself, another solute or the solvent), then, 2-tert-butyl-7-azaindole dimer, in which stacking with another molecule of 2-tert-butyl-7-azaindole is sterically hindered, should exhibit phosphorescence in an appropriate polar solvent such as chlorobutane but not in a non-polar one such as 2-methylbutane. In this work, both hypotheses were confirmed in the corresponding matrices in these two solvents at 77 K.