Synthesis of (NH)m(NMe)4−m-Bridged Calix[4]pyridines and the Effect of NH Bridge on Structure and Properties
摘要:
The (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines (m = 1-4) 19-23 were synthesized in excellent yields from deprotection of N-allyl groups of (NAllyl)(m)(NMe)(4-m)-bridged calix[4]pyridine derivatives 8 and 15-18, which were prepared in moderate yields by macrocyclic 2+2 and 1+3 coupling reactions between simple diamino- and dibromo-substituted fragments, In the solid state, (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines adopted different 1,3-alternate conformations due to mainly the formation of varied conjugation systems of bridging NH units with their neighboring pyridines. In solution, all (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines were very fluxional and the rates of interconversion of various conformational structures were very rapid relative to the NMR time scale, While (NH)(4)-bridged calix[4]pyridine 23 formed the strongest conjugation system, (NH)(2)(NMe)(2)-bridged calix[4]pyridine 21 acted as a selective fluorescence probe in the recognition of zinc(II) ion in solution with the dramatic enhancement of fluorescence intensity.
Synthesis of (NH)m(NMe)4−m-Bridged Calix[4]pyridines and the Effect of NH Bridge on Structure and Properties
摘要:
The (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines (m = 1-4) 19-23 were synthesized in excellent yields from deprotection of N-allyl groups of (NAllyl)(m)(NMe)(4-m)-bridged calix[4]pyridine derivatives 8 and 15-18, which were prepared in moderate yields by macrocyclic 2+2 and 1+3 coupling reactions between simple diamino- and dibromo-substituted fragments, In the solid state, (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines adopted different 1,3-alternate conformations due to mainly the formation of varied conjugation systems of bridging NH units with their neighboring pyridines. In solution, all (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines were very fluxional and the rates of interconversion of various conformational structures were very rapid relative to the NMR time scale, While (NH)(4)-bridged calix[4]pyridine 23 formed the strongest conjugation system, (NH)(2)(NMe)(2)-bridged calix[4]pyridine 21 acted as a selective fluorescence probe in the recognition of zinc(II) ion in solution with the dramatic enhancement of fluorescence intensity.
Proton-Assisted Reduction of CO<sub>2</sub> by Cobalt Aminopyridine Macrocycles
作者:Alon Chapovetsky、Thomas H. Do、Ralf Haiges、Michael K. Takase、Smaranda C. Marinescu
DOI:10.1021/jacs.6b01980
日期:2016.5.11
efficient reduction of CO2 to CO by cobalt aminopyridine macrocycles. The effect of the pendant amines on catalysis was investigated. Several cobaltcomplexes based on the azacalix[4](2,6)pyridine framework with different substitutions on the pendant amine groups have been synthesized (R = H (1), Me (2), and allyl (3)), and their electrocatalytic properties were explored. Under an atmosphere of CO2 and in
我们在这里报告了钴氨基吡啶大环化合物将 CO2 有效还原为 CO。研究了侧链胺对催化的影响。已经合成了几种基于氮杂杯[4](2,6)吡啶骨架在侧胺基上具有不同取代基的钴配合物(R = H(1)、Me(2)和烯丙基(3)),及其电催化性能进行了探索。在 CO2 气氛和弱布朗斯台德酸存在下,观察到大催化电流 1,对应于 CO2 还原为 CO,法拉第效率 (98 ± 2%)。相比之下,配合物 2 和 3 产生的 CO 的 TON 至少比 1 低 300 倍,这表明仲胺的侧链 NH 部分的存在对催化至关重要。而且,
Synthesis of (NH)<sub><i>m</i></sub>(NMe)<sub>4−<i>m</i></sub>-Bridged Calix[4]pyridines and the Effect of NH Bridge on Structure and Properties
作者:En-Xuan Zhang、De-Xian Wang、Zhi-Tang Huang、Mei-Xiang Wang
DOI:10.1021/jo901609u
日期:2009.11.20
The (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines (m = 1-4) 19-23 were synthesized in excellent yields from deprotection of N-allyl groups of (NAllyl)(m)(NMe)(4-m)-bridged calix[4]pyridine derivatives 8 and 15-18, which were prepared in moderate yields by macrocyclic 2+2 and 1+3 coupling reactions between simple diamino- and dibromo-substituted fragments, In the solid state, (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines adopted different 1,3-alternate conformations due to mainly the formation of varied conjugation systems of bridging NH units with their neighboring pyridines. In solution, all (NH)(m)(NMe)(4-m)-bridged calix[4]pyridines were very fluxional and the rates of interconversion of various conformational structures were very rapid relative to the NMR time scale, While (NH)(4)-bridged calix[4]pyridine 23 formed the strongest conjugation system, (NH)(2)(NMe)(2)-bridged calix[4]pyridine 21 acted as a selective fluorescence probe in the recognition of zinc(II) ion in solution with the dramatic enhancement of fluorescence intensity.