Visual Chemical Logic Operation Based On MoO₃ Nanomaterials

Firstly,this paper summarizes the research status of chemical logic operations,especially visualized molecular logic operations.Boolean logic operations based on silicon materials have made great contributions to the development of computers.Recently,chemical logic operations have been able to store information at the molecular level,making them the basis for the manufacture of microcomputers.In addition,this kind of logic operation involves a series of physical and chemical reactions,and has good application potential in chemical synthesis,biosensor and disease treatment.Nowadays,noble metal nanomaterials such as gold,silver and platinum nanomaterials have been used to design a variety of basic visual logic gates and advanced logic circuits with specific modifiers because of their high molar absorptivity and chemical stability.However,there are few studies on other plasmonic materials such as molybdenum oxide.In this research,single-layer molybdenum trioxide（MoO₃）nanosheets were prepared by grinding-ultrasonic assisted liquid phase peeling.The MoO₃ nanosheets were converted into plasmonic molybdenum oxide(MoO_3-x)nanomaterials with localized surface plasmon resonances（LSPR）by introducing a series of reductants.The crystal structure,morphology and LSPR control conditions of the two nanomaterials were studied.It is used to develop a series of visualized chemical logic gates,signal selectors,intelligent voting system and advanced negative feedback logic circuits.The main research contents are as follows:1.A method of grinding-ultrasonic assisted liquid phase peeling was employed to prepare MoO₃ nanosheets.The transverse size of the nanosheets prepared is micron,but its thickness is only about 1.2 nm.Oxygen vacancy doping of MoO₃ nanosheets with reducing reagents at room temperature and pressure was used to make them possess LSPR and transform them into MoO_3-x nanosheets.The crystalline structure,size and LSPR of two molybdenum oxide nanomaterials were characterized by X-ray diffraction,transmission electron microscopy and ultraviolet-visible spectrophotometer.LSPR of molybdenum oxide nanomaterials was regulated by a series of reductants（sodium borohydride,ascorbic acid and stannous chloride）and oxidants（sodium hypochlorite and hydrogen peroxide）,and a series of visualized chemical logic gates（AND,NAND,OR,NOR,XOR,XNOR,XNOR,and INH）were constructed.In addition,a 1:2 signal selector with advanced operation rules is constructed by integrating basic AND logic gates and INH logic gates.All constructed visual logic operations have good operational ability.2.The contrary logic pairs and logic circuit based on MoO_3-x nanodots and3,3’-diaminobenzidine（DAB）have been developed.Molybdenum oxide nanosheets were directly reduced and etched by sodium borohydride to form nanodots with LSPR.The diameter of the nanodots were 1.78±0.26 nm,and the dispersion showed obvious blue color.In the presence of oxidant,the LSPR disappeared and the color changed from blue to colorless,while DAB was oxidized to oxidized DAB（ox-DAB）,and the color of solution changed from colorless to brown.MoO_3-x nanodots and DAB exhibit distinct contrary color responses to oxidants.Accordingly,a series of visual logic pairs and logic circuits have been developed,including YES-NOT,AND-NAND,OR-NOR,XOR-XNOR,INH-IMH and MAJ-MIN,and intelligent logical voting system with“one-vote deny”function.Compared with the logic operation designed separately before,it greatly simplifies the operation,reduces the cost and improves the efficiency of logic gates and logic circuits.3.A advanced logic circuit based on chemical reaction,negative feedback logic circuit,was established by skillfully coupling the dephosphorization of glutathione（GSH）in the presence of Cu²⁺ions and the reduction of MoO₃ nanosheets by GSH in acidic conditions to form MoO_3-x nanosheets.During the research,it was found that the conversion of MoO₃nanosheets to MoO_3-x by GSH was highly dependent on the pH value.Only within a suitable range of pH value,the reaction could proceed well,resulting in obvious LSPR,and the color of the solution changed from colorless to blue.The interaction between GSH and Cu²⁺ions can provide protons,reduce the environmental pH value,and promote the reaction between GSH and MoO₃ nanosheets.This reaction will lead to the suspension of the reaction between GSH and Cu²⁺ions in order to realize the negative feedback logic loop.The negative feedback logic loop can effectively control the concentration of Cu²⁺ions by changing the amount and proportion of reagents,indicating that it may be able to effectively control the sensing,biomarker,organic synthesis,catalysis and other related reactions.At the same time,the negative feedback logic loop can control the formation of plasma MoO_3-x nanosheets,which means that it also has great potential applications in intelligent photothermal therapy,stimulus response drug delivery,plasma imaging and surface enhanced Raman.