Squaric acid is an unusually strong acid for an organic acid:
It's also unique because of its strained ring. In general, five- and six-membered rings dominate in chemistry - hence the endless parade of hexagons. Higher rings are tolerated but not-so-favored. Lower rings are possible, but, again, unfavored, because one tends to find atoms' electrons in clouds that don't overlap so well in this configuration. Along with some other moderately strong organic acids (such as the ubiquitous "alpha-hydroxy acids"), it's attracted some attention for (prescription) dermatological use.
Oh boy oh boy oh boy! Acetylene dicarboxylic acid diperoxyesters, -OO-t-Bu, -OO-CF3, -OO-SiMe3, your choice. Frozen matrix then photolyze to get .C#C. (acetylene diradical) insulated by a CO2 on either end. Wouldn't that be the Big O for spectroscopists and organic theory scum? (C2 Swan band emissions in comet tails, (0,1)/563.5 nm, (0,0)/516.5 nm, (1,0)/473.7 nm, (2,0)/438.2 nm.) It's got to rehybridize when cold, but to what? Degeneracy = publishable.
Warm the matrix to get radical recombination and RO-C#C-OR. Acetylene diethers are trippy. But wait! Iodine trap half, get a [(pi)2a+(pi)2a] for the unsaturated four-membered ring (we are sooo naughty!). Hydrolyze, get squaric acid.
If you hurry the RFP and PO you can bootleg it over X-mas to New Years. Admittedly that first step is potentially explosive and acetylenedicarboxylates require some art to be made. Nasty for skin contact, too. Could it be more fun?