Metal Halides Encapsulated In Viologen-based Cationic Frameworks:A New Type Of Hybrid And Their Opt/electrical Properties

Viologen-based opt/electrical functional materials have exhibited attractive applications in many significant fields such as opt/electrical conversion,photo/thermochromism,molecular switching and information storage.In this field,opt/electrical functional materials with high-sensitivity and high photo/thermal stability are the focus.Novel hybrid structures with anionic nanoclusters or nanowires encapsulated in cationic frameworks are expected to achieve breakthroughs in the performance of such materials.Bipyridine oxide has a versatile coordinated modes,excellent structural flexibility,high melting point,which might contribute to the formation of hybrids with high stability.At present,the study of functional materials based on bipyridyl oxide cation framework is still in its infancy,and the effect of encapsulated halide nanoclusters or nanowires on the properties of the material is not clear.Therefore,the study about the synthesis,ophotoelectric propertie of this kind of viologen-based functional materials will be significant.Keep this idea in mind,in this paper,the cationic frameworks were constructed from neutral viologen-bipyridyl oxides and main group metals/rare earth metals,0-D clusters or nanowires based on the second metal(Ag,Cu,Bi)halides were used as encapsulated moieties.Consequently,15 novel organic/inorganic heterogeneous metal hybrids were obtained.Among them,in 1-9,[Ag(Cu)/I2]nn’,[BiI5]n3n-nanowires were encapsulated in cationic frameworks.Compounds 10-15 are the hybrid structures consist of[Ln2(dpdo)(DMF)14]6+ metalliviologen and(Bi2I9)3-cluster/(Ag12I18)n6n-one-dimensional chains.All compounds were characterized by IR,UV-Visible diffuse reflectance,photocurrent and thermochromism.15 compounds exhibit good photocurrents,among which compound 11 is the strongest with the photocurrent intensity of 1.3×10-6A.In addition,compounds 10-15 possess excellent reversible thermochromism behavior,and the color change temperature of compound 10-12 are in the range of-196-160℃.These are the rare examples of stable reversible thermochromic materials with three colors upon heating,which can be used in molecualr switch and information storage devices.In addition,the photocurrent and the thermochromic mechanisms were also discussed.These study can provide a theoretical guide for the design and synthesis of opt/electrical conversion materials and thermochromic materials.