A Reaction Coupled Dynamic Self-assembly System Of Au(I)-thiolate

Life system represents the zenith of self-assembly,in which complexity is an important feature.The complexity includes not only the hierarchical structures throughout all length scales,but also their highly dynamic adaption to the environments.The representative example is the stem cells,which can develop into different tissues or organs depending on the environments.It is highly important to develop artificial systems that can develop into different structures from the same starting materials upon the change of environments to help understand such mystery phenomenon and construct artificial intelligent systems.It has to be mentioned that the highly adaptive systems here have inherent differences from the ubiquitous systems in which different conditions lead to different products.The former requires the constant change in compositions/structures of the assembly,while in the latter,the compositions/structures of the assembly are invariable with time.Studies on the adaptive behaviors in artificial self-assembly systems had been focused on the responsiveness of the already finished assemblies to external chemical/physical stimuli,and used it for the preparation of functional/intelligent materials.In recent years,people have developed the system with dynamic assembly processes through the exchange of substances/energy with the assembly system.In this aspect,dissipative/non-equilibrium assembly has been realized by coupling with reactions such as esterification,hydrolysis and so on,to mimic successfully the process of realizing function in energy-consumption conditions in life system,and some special reactions,such as hydrolysis,polymerization and so on,have been applied to trigger the assembly to construct complex structures or realize some special functions.These groundbreaking pieces of work have promoted self-assemblies to transfer from static ones to dynamic ones.However,reactions that can couple with the self-assembly arestill limited,because they have to match the conditions and rates of self-assembly.What's more,the reactions are usually used to trigger the on-off the assembly,the dynamic change of the compositions or structures of products upon environmental conditions haven't been realized by coupling with environment-sensing reactions.To construct such a highly dynamic reaction-coupled self-assembly system,it needs at least two following conditions: first,the system should have enough complexity to show multiple stable/metastable structures so that it can adjust its structures upon the environmental change;secondly,it should contain components to recognize the change of environments and respond to it and lead to the change of structures.After years of our group studying on the self-assembly behavior of Au(I)-thiolate coordination polymer,we realize that it is very promising for it to develop into a highly dynamic system to construct unprecedented complex structures and show environmental adaptions.The uniqueness of Au(I)-thiolate includes: i)it has the excellent structural tailorability and show several stable/metastable structures upon the environmental change,and it can achieve double-ligand co-assemblies;ii)the synthesis of Au(I)-thiolate is accompanied with a thiol to disulfide oxidation reaction,making the reaction coupled self-assembly possible.In this paper,we used double-ligand co-assembly strategy,by pH manipulating the comparable rates between the thiol-disulfide exchange,ligand exchange reactions and the self-assembly,due to the difference in the oxidation reaction,thiol-disulfide exchange and ligand exchange reactions of the two ligands themselves,the highly dynamic assembly process of the compositions of the assemblies continuously changed with time were realized.Most importantly,due to real-time changes in the assembly compositions,spatially inhomogeneous assembled structures were realized via a spontaneous partial disassembly-reassembly process.This work shows the first example that an artificial system can change its compositions dynamically with time without any external disturbance by coupling wiht self-carried reactions,and provides a new stragegy to achieve complex bio-mimic structural materials and promotes the development of dynamic,adaptive supramolecualr assemblies.