Study On Synthesis Of Tb³⁺-doped MgAl/ZnAl-LDHs And Their Fluorescence Response To Amino Acid Molecules

A series of Tb³⁺-doped MgAl-LDHs and Tb³⁺-doped ZnAl-LDHs have been synthesized by co-precipitation method using Mg?NO_3?2·6H₂O,Zn?NO_3?2·6H₂O,Al?NO₃?₃·9H₂O,Tb₂O₃ and NH₃·H₂O as main materials.The composition,structure,and fluorescent property have been investigated in detail.The results revealed that Tb³⁺-doped compounds had typical LDH structure,and exhibited green emission due to 5D4-7F5 and 5D4-7F6 transitions of Tb³⁺ ions.Furthermore,the effects of annealing on the Tb³⁺-doped LDHs were examined.It was found that the structure of LDHs collapsed at about 200?,oxides occurred between 400 and 600?,and the spinel structure formed at 800?;while the fluorescence of Tb³⁺-doped MgAl-LDHs and Tb³⁺-doped ZnAl-LDHs have different changes with the increase in the annealing temperature.These different fluorescent changes may be related to the chemical environment of Tb³⁺ ions.In addition,the fluorescence of the Tb³⁺-doped LDHs response to amino acid molecules was studied.Results suggested that the structure of LDH did not change significantly when the Tb³⁺-doped MgAl-LDH was exposed to different concentrations of lysine solution,but the green emission attributed to Tb³⁺ions markedly decreased even quenched,and the emission ascribetd to lysine had different changes.After the Tb³⁺-doped ZnAl-LDHs reacted with different concentrations of tryptophan,the green emission attributed to Tb³⁺ ions quenched and the emission owed to tryptophan enhanced.However,the structure of Tb³⁺-doped ZnAl-LDH changed obviously because of some new reflections which may be due to the hybride of Tb³⁺-doped ZnAl-LDH and tryptophan.The fluorescence of Tb³⁺-doped LDHs response to amino acid molecules may be due to the interaction between the Tb³⁺-doped LDHs and amino acid molecules,and the interact mechanism is possibly relevant to hydrogen bond.