Crystal structure determination as part of an undergraduate laboratory experiment: 1′,3′,3′-tri­methyl­spiro­[chromene-2,2′-indoline] and 1′,3′,3′-trimethyl-4-[(E)-(1,3,3-tri­methyl­indolin-2-yl­idene)meth­yl]spiro­[chroman-2,2′-indoline]

The crystal structures of the title compounds, C(19)H(19)NO and C(31)H(34)N(2)O, were determined as part of an experiment in an undergraduate teaching laboratory that demonstrates the relationship between mol­ecular structure and function. 1′,3′,3′-Tri­methyl­spiro­[chromene-2,2′-indoline] is both a photoswitch and thermochromic mol­ecule. Students synthesized it and a bis-indoline adduct and compared the crystallographically determined structures to computed gas-phase models.