)-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。
Azidocryptands–synthesis, structure, and complexation properties
作者:Christina Tönshoff、Klaus Merz、Götz Bucher
DOI:10.1039/b413395a
日期:——
Cryptands bearing an intraannular azido substituent have been synthesized and characterized spectroscopically. Their complexation properties were investigated by picrate extraction analysis. The oxygen-containing cryptands were found to be good ligands for alkali cations, with a preference for Li(+) and Na(+). The molecularstructure of the complex with KBr was determined by X-ray crystallography.
Photochemistry of an Azido-Functionalized Cryptand: Controlling the Reactivity of an Extremely Long-Lived Singlet Aryl Nitrene by Complexation to Alkali Cations
Photolysis of the cryptand 1, bearing an intraannular azido substituent, results in a complexphotochemistry. Low-temperature photolysis yields the triplet nitrene (3)2, which has been characterized by EPR spectroscopy. Small differences in ZFS parameters are detected between the uncomplexed nitrene-functionalized ligand (in EtOH: D' = 0.93 cm(-1)) and its sodium (NaBr@(3)2 in EtOH: D' = 0.88 cm(-1))
Abnormal reaction of an aryl azide confined in a calix[6]arene skeleton
作者:Norihiro Tokitoh、Toshiyuki Saiki、Renji Okazaki
DOI:10.1039/c39950001899
日期:——
Photolysis of an arylazide embedded in a m-phenylene-bridged p-tert-butylcalix[6]arene 2 results in the formation of unusual reaction products 3 and 4via the transannular addition reaction of an initially formed nitrene intermediate; the molecular structure of 4 was determined by X-ray crystallographic analysis.