Synthesis And Properties Of Trimacrocyclic Hexasubstituted Benzenes And Superphanes

The design and synthesis of functional supramolecular receptors has been a topic of great interest to chemists.Although the study of macrocycles and cages has made rapid progress in the past few decades,the sustainable development of novel functional molecular systems is still an important research topic in the field of supramolecular chemistry at present and for a long time in the future.Hexasubstituted benzene has the characteristics of easy modification,multiple derivable sites and high symmetry.Hexa–substituted benzene derivatives have become a kind of functional molecular systems with diverse structures,excellent properties and wide application.Due to the characteristics of easy modification,multiple derivable sites and high symmetry,the derivatives of hexasubstituted benzene have become a kind of functional molecular system with diverse structure,excellent performance and wide application.The six substituent groups in the functional system of hexasubstituted benzene reported so far are mainly divergent and have greater degrees of freedom.Therefore,the existing hexasubstituted benzene functional receptors are often less than ideal in their ability to bind and selectivity towards the guest molecule.This paper focuses on how to improve the recognition ability and selectivity of hexasubstituted benzene functional receptors for specific guest molecules.A new class of trimacrocyclic hexasubstituted benzenes functional receptors was designed and synthesized based on the multiple macrocyclization effect,achieving highly selective recognition of guanidine groups and halogen ion solvent cluster–mediated self–assembly,respectively.Meanwhile,based on the multiple cage effect,we developed a new class of superphane based functional molecular system by using the dynamic imine covalent strategy,and realized the capture of octamer water clusters and the efficient and highly selective removal of organic pollutants,which has potential application in modern separation materials,resource recovery,environmental remediation and other fields.Details of the research are as follows:（1）A new class of trimacrocyclic hexasubstituted benzene THB–1,was synthesized using Co₂（CO）₈–catalyzed[2+2+2]tricyclization of monoacetylene crown ethers,and the self-assembly behavior of[X（CHX₃）₆]^–（X=Cl^–,Br^–,I^–）cluster-mediated was first discovered.The crystal structure shows that the guanidine group is bound in a three–dimensional cavity of the functional subject,while a halogenated chloroform cluster is stabilized between the two complexes.The X（CHCl₃）₆]^–cluster was also able to mediate the self–assembly behavior between the trimacrocyclic hexasubstituted benzenes and the guanidinium halide salt with similar efficiency under rapid mixed crystallization conditions.We show for the first time that extremely unstable anionic solvent clusters can also act as a class of assembly motifs to mediate the formation of stable self–assembled structures.（2）By reducing the size of the acetylene crown ether,two trimacrocyclic hexasubstituted benzenes THB–2 and THB–3 with different cavity sizes were synthesized.The optimized trimacrocyclic hexasubstituted benzenes THB-3 exhibited enhanced affinity and selectivity for guanidine hydrochloride.The ability to extract the guanidine group from its solid salt into the organic phase and antibacterial experiments showed that the receptor THB-3 was able to transport guanidine hydrochloride across the cell membrane,significantly enhancing the growth inhibition of guanidine hydrochloride against Helicobacter and Bacillus subtilis cells for anticancer or antibacterial purposes.（3）Based on the[2+2+2]cycloaddition reaction,the key intermediate of hexyl（3-formylphenyl）substituted benzene HPB–CHO was synthesized and the imine–based superphane cage C3–I–S was successfully synthesized with malondiamine through dynamic covalent imine strategy.This molecular cage can be converted to the more stable secondary amine C3–I–S by reduction with sodium borohydride.The cavity size of secondary amine superphane can be regulated by the tied and untied between formaldehyde and cage.In addition,X–ray single crystal structure analysis revealed that C3–I–S can be used to identify cavities to stabilize the superstructure of an octamer water cluster.The size of the cavity of the secondary amine superfluid can be regulated by the tying and untying of formaldehyde to the molecular cage.C3–I–S can use its recognition cavity to stabilise an octamer water cluster and control the binding and release of the octamer water cluster by regulating the size of the cavity.（4）A series of tbu–S,C8–S,OH–S,Py–S,t Py–S containing acylhydrazone were obtained by[2+6]one–pot condensation method using HPB–CHO and aromatic diacylhydrazine as the building blocks.As inferred from the host–guest chemistry studies,acylhydrazone based superphane was found able to bind commonly seen dye molecules,e.g.,methylene blue（MB）,crystal violet（CV）,acridinine orange（AO）,etc.,and certain drug molecules such as paraquat（MV）,propolafolol hydrochloride（PHCl）,as well as some perchlorate salts,e.g.,Li Cl O₄,Na Cl O₄,Zn Cl O₄and TBACl O₄.Notably,this superphane exhibited good selectivity to Na Cl O₄.The single crystal structure of the（tbu–S）·（MV）complex shows that the superphane containing acylhydrazone is capable of simultaneously encapsulating multiple chloride ions within its cavity through multiple C–H…Cl,N–H…Cl,C_sp2–H…Cl hydrogen bonding interactions.At the same time,the positively charged MV²⁺is stabilized between the superphane arms by cation–πinteractions and C–H…πinteractions.（5）Based on the study of the host–guest chemistry between the acylhydrazone Superphanes and the guest molecule,a class of superphane based supramolecular conjugated polymer（AH–SMP）was prepared by cross–linking the side chain modifiable hydrophilic acylhydrazone molecule cage OH–S with tetrafluoroterephthalonitrile（TFN）,which is highly efficient in the removal of organic micropollutants from water and has good recoverability.A comparison study on the adsorption performance of acylhydrazone OH–S with the cross–linked polymer AH–SMP on organic micro–pollutants in water revealed that AH–SMP showed much higher adsorption performance and higher selectivity for cationic pollutants（MB,AO,NR,CV,MV,RB,PHCl）.Much to our surprise,within 1 min,the adsorption efficiency of these organic pollutants by AH–SMP can be>90%.Notably,the polymers showed the best selectivity and adsorption properties for methylene blue（MB）.Within 15 s,the polymer AH–SMP can remove96%MB from water,and the adsorption efficiency can reach 99.9%within 1min.The apparent adsorption rate constant is 2.4336 g mg^–1min^–1（869times higher than that of OH–S）.The maximum adsorption capacity can reach up to 645 mg g^–1.In addition,the maximum adsorption capacity of AH–SMP for the pesticide molecule methyl viologen（MV）and the drug molecule propranolol hydrochloride（PHCl）was 246 mg g^–1and 500 mg g^–1,respectively,and its adsorption efficiency has surpassed most reported porous adsorbent materials with high specific surface area.This work provides a new insight into the development of advanced adsorbent materials with high efficiency and high selectivity.