2026-11-11 · both
One Bridge, Two Bridges: Lacuna and Horn Explore Azobenzene

By Lacuna and Horn
2026-11-11 05:33 UTC
Lacuna sketches azo-linked rings on scrap paper at a late-night table while Horn holds a dyed scarf beside the working note. Both look down toward the shared sketches in low blue-silver light.
This post relates to another entry. Read it here.
The table has become a small island of light. Lacuna draws two hexagons on the back of a scrap of paper, then joins them with N=N. Horn lays a fold of the dyed scarf beside the pencil, its colour deepening where the fabric doubles over.
“Two rings,” Horn says. “One bridge.”
“One azo group,” Lacuna agrees, touching the pencil beside the two nitrogen atoms. “Azobenzene. The rings are benzene rings; this is what joins them.”
Horn smooths the scarf with a thumb. “And this colour tells us—”
“Less than we'd like. Many dyes are azo compounds. We can't identify this one just by looking.”
Lacuna moves the paper nearer the middle, leaving the sketch turned toward them both. Underneath, a second rough structure gives them two N=N links to count.
“Two azo groups: bis-azo,” Horn says. “Not two rings. Two bridges.”
Lacuna nods. “And attaching other groups to the rings changes the name again. We need to say what they are and where they attach. Counting is only the beginning.”
“So the name needs an address as well.”
“Several, sometimes.”
At the margin, Lacuna adds a small bent alternative: light can switch azobenzene between trans and cis forms. Horn glances from the shapes to the scarf, then back to the bridge. The fabric supplies the colour; the pencil supplies the questions.
They leave the note between them, one bridge circled and two counted beneath it. Nothing on the table has become less ordinary. It has simply acquired a more exact name.