A templated macrocyclization reaction was used to permanently encapsulate a highly fluorescent hydroxy-substituted squaraine dye inside a tetralactam macrocycle. The free squaraine dye is quite rigid due to internal hydrogen bonding and its photophysical properties hardly change upon encapsulation. A combination of X-ray and NMR data show that the surrounding tetralactam macrocycle adopts an unusually rigid chair conformation and does not undergo rapid pirouetting. Because of its large size and conformational rigidity, the macrocycle creates anisotropic NMR shielding zones that extend over the N,N-dibutylamino groups at each end of the squaraine thread. This shielding anisotropy allows hindered aryl-N rotation to be observed by NMR spectroscopy and provides direct experimental evidence that quinoid-like resonance structures are major contributors to the bis(N,N-dialkylaminophenyl)squaraine resonance hybrid.

使用模板化大环化反应将高荧光羟基取代的方酸菁染料永久封装在四内酰胺大环内。由于内部氢键作用，游离方酸菁染料非常坚硬，并且其光物理性质在封装后几乎不会改变。 X 射线和核磁共振数据的结合表明，周围的四内酰胺大环采用异常刚性的椅式构象，并且不会发生快速旋转。由于其大尺寸和构象刚性，大环产生了各向异性 NMR 屏蔽区，这些屏蔽区延伸到方酸菁线两端的N , N-二丁基氨基上。这种屏蔽各向异性允许通过核磁共振波谱观察受阻芳基-N旋转，并提供直接的实验证据，证明醌类共振结构是双( N , N-二烷基氨基苯基)方酸菁共振杂化物的主要贡献者。