Notes on molecules, models, and computation.

A four-point series of para-X-benzylidenemalononitriles (X = H, F, NH₂, NMe₂) shows how donor strength moves the HOMO and LUMO, and explains why para-fluorine acts as a weak net donor in this minimal push-pull scaffold.

A three-point series of para-methoxy push-pull dyes with CN, DCV, and TCF acceptors shows how acceptor strength moves the HOMO and LUMO, and how the HOMO-LUMO gap closes as the acceptor strengthens.

The blinking-to-absorption note modeled a fluorescent dye as two levels and named what that hides. Computing the actual excited-state manifold of DCDHF-Me2 — a push-pull dye engineered for single-molecule imaging — gives a sharper answer than we planned. Its visible absorption is essentially one transition, and the rest of the manifold lives in the deep UV; benzene, the dye's own parent ring, shows the opposite arrangement for a reason symmetry makes plain.

A single fluorescent molecule blinks; a cuvette full of the same molecules gives a smooth absorption band. The two pictures are the same Jablonski diagram read at different scales — one molecule versus an ensemble, one photon at a time versus a steady-state rate. This post traces the path from quantized absorption and emission events to a bulk spectrum, and extends the same diagram to two-photon absorption as the nonlinear version of the same transition.

I ran an app-development workflow as four separate Claude Code sessions — each owning one role, all talking through a shared inbox — and then pointed a fresh session at the accumulated messages and asked it to write the skills. This is how the bootstrap worked, why the distillation step is the interesting part, and what it cost.