Synthesis And Properties Of Rare Earth Responsive Color-changing Materials Based On Viologen Carboxylic Aci

The unique electron-deficient properties of viologen metal coordination polymers(Cps)make them promising for a wide range of applications in multifunctional materials such as stimulus response and sensor devices.Corresponding studies have shown that these materials have great applications in areas such as photomagnetism,photocontrolled fluorescence,and hazardous gas detection.However,there are still relatively few reports on multistimulus-responsive chromophoric complexes combining viologen with lanthanides.Therefore,the construction of multi stimulus-responsive lanthanide multifunctional materials using viologen and its derivatives as ligands has a promising application.In view of this,eight viologen-based Lanthanides Cps and one viologen-based transition metal Cp were constructed by N,N’-4,4’bipyridiniodipropionate(L).The complexes have been studied in response to photostimulation and amine stimulation,and some of them exhibit the properties of color change in response to stimulation and are accompanied by changes in physical properties such as fluorescence and magnetism.The main works are as follows.Eight viologen-based lanthanides complexes were synthesized from N,N’-4,4’bipyridiniodipropionate and lanthanides chloride hexahydrate:{[LnL(H2O)4]Cl3·3H2O}(L=N,N’-4,4’-bipyridiniodipropionate,Ln=Dy(1),Eu(2),Tb(3),Ce(4),Gd(5),Sm(6),Nd(7),Er(8)).The photochromic properties of complexes 1-8 were carefully investigated,in which complexes 1-3 were also accompanied by changes in fluorescence intensity,exhibiting an obvious photocontrolled fluorescence behavior.More noteworthy is that complex 1 also displays remarkable photomagnetic properties.It was also able to show different color responses under different sizes of ammonia/amine atmosphere.Furthermore,in the exploration of the association of viologen ligands with transition metals,a viologen-based transition metal complex composed of N,N’-4,4’-bipyridinedipropionic acid and hexacyanoferrate was obtained:{(H2L)3[Fe(CN)6]2·4H4O}n(9).Complex 9 also responds positively to UV light and exhibits a typical single-molecule magnetic behavior.Finally,the complex 1 was made into a dual-function paper and applied to inkless erasable printing and ammonia/amine atmosphere detection.