)-bridged calix[6]arenes with four uncapped hydroxy groups at the lower rim and various kinds of functionalities on the bridging unit were synthesized. Their structures in solution and in the crystalline state were determined by NMR spectroscopy, molecular mechanics calculations, and X-ray crystallographic analyses. They were found to adopt a pinched cone conformation, where the bridging 1,3-phenylenebis(methylene)
合成了 1,3-亚苯基双(亚甲基)-桥连杯[6]芳烃,其下缘有四个未封端的羟基,桥接单元上有各种官能团。它们在溶液中和结晶状态下的结构通过核磁共振光谱、分子力学计算和 X 射线晶体学分析确定。发现它们采用收缩锥体构象,其中桥接的 1,3-亚苯基双(亚甲基)单元位于下方,从而形成锥体的底部。这些分子中有很强的分子内氢键网络,形成环状阵列;该网络被认为在稳定收缩锥体构象方面发挥着重要作用。还研究了桥接单元的构象迁移率。
Syntheses of Dihydropyrene–Cyclophanediene Negative Photochromes Containing Internal Alkenyl and Alkynyl Groups and Comparison of Their Photochemical and Thermochemical Properties
作者:Khurshid Ayub、Reginald H. Mitchell
DOI:10.1021/jo4024446
日期:2014.1.17
Synthesis of a variety of 8,16-disubstituted-anti-[2.2]-metacyclophanedienes (CPD) with alkenyl and allcynyl internal (8,16) groups is described together with their analogous dihydropyrenes (DHP). Eyring and Arrhenius parameters were determined for the thermal closing reaction, CPD to DHP, and half-lives at 20 degrees C were found to range from 11 days (X = CHO) to 36 years (X = CN), with alkenyl functions being from 56 days to 10 years. The visible light opening reaction, DHP to CPD, showed relative rates of 1 (X = CN) to 240 (X = CH=CMe2).