Design And Synthesis Of Novel Structures Assisted By Coordination Bonds

Coordination bonds(CBs)attracted considerable attention due to their advantages in many aspects,such as the moderate strength,diverse coordination modes,and dynamic reversibility.Millions of metal coordination complexes have been self-assembled via coordination bonds.They show potential applications in many fields,particularly in gas storage and separation,catalysis,optoelectronic devices,and magnetic materials.Based on the features of CBs,this thesis focuses on the design and synthesis of CB-assisted materials with novel structures.They include CB-assisted woven covalent organic frameworks,and[N…I+…N]halogen bonded supramolecular cages or polymers constructed via CBs.The details of this thesis are as follows:In chapter 1,the development of coordination bonding theory was first reviewed,followed by the briefly introduction of the characteristics of coordination bonds.And then the application of coordination bonds in functional materials and structural design was summarized.In the last part of this section,the significance and purpose of the topic of this thesis were proposed.In chapter 2,a CB-assisted three dimensional woven covalent organic framework was obtained by cleverly designing the one-dimensional organic chains and metal ions to be linked through CBs.The specific path was using the specific geometry of the complex precursor and the stability of the chelate coordination bond.Firstly,a simple complex of ML2 type tetrahedron was constructed,and the amine group was introduced into the four end points of the complex.Then,a three-dimensional framework network consisting of one-dimensional chains interwoven by coordination bonds was synthesized by dynamic covalent bond polymerization with another linear organic dialdehyde linker.The obtained anionic mesoporous framework structure was confirmed by various experimental means and theoretical simulations,which proved the feasibility of the design.In chapter 3,the reaction of a linear imidazole silver coordination complex with molecular iodine forming[N…I+…N]based complexes was investigated.Coordination of Ag+ with N-aromatic rings usually forms linear bicoordinate compounds.In the presence of molecular iodine,I2 reacts with Ag+ and breaks Ag…N bonds.The resulted I+ would in-situ replace the position of Ag+ in the complex,thereof converting the[N…Ag+…N]CB to[N…I+…N]halogen bond(XB).In this work,in addition to the iodonium complex,we also separated some iodinated imidazole compounds by adjusting the stoichiometry.The results were confirmed by X-ray single crystal crystallography and nuclear magnetic analysis.To test if the[N…Ag+…N]CBs are able to be used to assist the construction of XB cage and XB polymer containing[N…I+…N]units,in Chapter 4,we adopted flexible tripodal pyridyl compounds as ligands.The silver metal organic cages and polymers were first prepared,which further reacted with molecule iodine.It was found that the molecular iodine can break the CB and insert the I+in between the two pyridine rings.Nevertheless,we finally failed to obtain the corresponding single crystals due to the high activity of the I+ species.Instead,three XB complexes containing N…I-I moieties were crystallized.The structural details were described in this chapter.The last chapter involves the summary of this thesis as well as the prospect of the new type compounds that constructed with assistant of CBs.