Spectroscopic Probing of the Dynamic Self-Assembly of an Amphiphilic Naphthalene Diimide Exhibiting Reversible Vapochromism
作者:Mohit Kumar、Subi J. George
DOI:10.1002/chem.201101642
日期:2011.9.26
Fluorescent nose: The reversible “turn‐on” vapochromism of a self‐assembled amphiphilicnaphthalenediimide derivative in solution and film states is presented. This property was found to be due to solvent–vapor‐responsive, dynamic reorganization in molecular packing in going from J‐type aggregates (blue fluorescent; see left‐hand side of scheme) to preassociated H‐type excimer states, with enhanced
Molecularclip 1 remains monomeric in water and engages in host–guest recognition processes with suitable guests. We report the Ka values for 32 1⋅guest complexes measured by 1H NMR, UV/Vis, and fluorescence titrations. The cavity of 1 is shaped by aromatic surfaces of negative electrostatic potential and therefore displays high affinity and selectivity for planar and cationic aromatic guests that
分子夹1在水中仍然是单体,并与合适的客人一起参与宿主-客体识别过程。我们报告了通过1 H NMR,UV / Vis和荧光滴定法测得的32个1⋅客体配合物的K a值。1的腔体由负电势的芳族表面形成,因此对平面和阳离子芳族客体显示出高亲和力和选择性,这使其与CB [ n ]受体相区别,后者比脂族客体更喜欢脂肪族。静电作用在识别过程中起着主要作用,在此过程中,铵离子和C = O的1个基团之间可能发生离子-偶极相互作用。情况下,SO之间3 -基团的1和在来宾悬垂阳离子基团,和空腔内1由阳离子-π相互作用。宿主1对具有大的平面芳族表面(例如萘二酰亚胺NDI +和per二酰亚胺PDI +)和衍生自a啶的阳离子染料(例如亚甲基蓝和天蓝色A)表现出较高的亲和力。通过比较类似的中性和阳离子客体(例如,亚甲基紫与亚甲基蓝;喹啉与N-甲基喹啉鎓; a啶与N-甲基ac啶;中性红与中性红H +)可以确定阳离子-π相