,'-Diarylsquaramide and ,'-dialkylsquaramide are conformationally stable linkers with extended (trans, trans) and folded (cis, cis) structures, respectively, independently of external conditions. Here, we show that -monomethylated ,'-diarylsquaramides generally take a (trans, cis) structure in the crystal but show a solvent-dependent conformational equilibrium in solution. In particular, the stable conformer of -methyl-,'-bis(1-naphthyl)squaramide () changes depending upon the solvent. Thus, aromatic -monomethylated squaramides could find application as components of environment-responsive molecular switches.
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