Synthesis, Structure And Modification Studies Of Ortho-Linked Oxacalix[n]arene[n]hetarenes

The design and synthesis of host molecules is an important area of research and innovation source of supramolecular chemistry. For a long time, the main research focus on this area is to find host molecules that are convenient to synthesize, have unique structures and abilities to recognize'guest molecules', or have self-assembly properties. The emergence of any new'host molecules'will not only accelerate the development of supramolecular chemistry, but also promote the crossing development between this field and other subjects. Such as, biological, physical, material, environmental and information sciences, which could eventually produce new materials and new products.With the rapid development of Calixarenes and resorcin[4]arene in the field of supramolecular chemistry, the study of hetero-atom bridged calixarene macrocycles (derivatives of the structure of calixarene) in supramolecular chemistry has aroused great interest in recent years. Through the changes of aromatic ring structures and the bridging atoms (such as, S, N, O), the diversification of spatial structures of calixarene structures could be realized, and the objective of modulating the size and the shape of the cavity, and thus the binding abilities towards different guest molecules could also be achieved. In this paper, we present the design and synthesis of several new O-bridged asymmetric'calixarene', and their modification have been explored.1. By employing diphenols and chloro-substituted aza-aromatic ring (or triazine) as precursor, we have synthesized four asymmetric nitrogen containing oxocalixarenes. Their structures have been confirmed by1-NMR,13C-NMR, HRMS and single crystal X-RAY analysis. Structure analysis revealed that some of the structural isomers adopted completely different conformations in the solid state. For example, ortho-bridged oxocalix[3]arene[3]pyrimidine adopts a core conformation with C3 symmetry, while ortho-bridged oxocalix[3]arene[3]pyrazine adopts an 1,3,5-alternate conformation.2. By the analysis structural conformation of the known hetero-atom bridged oxacalixerenes, we designed several new O-bridged asymmetric'calixarene' analogues and modified their structures, two other new derivatives were thus obtained.