Solid State Grinding Controlled Synthesis And Reversible Transformation Between Metal-Organic Salts And Their Correspding Complexes

Second-sphere coordination refers to those intermolecular interactions with the protonated second ligand directly bound to the primary coordination sphere of traditional metal complexes. In recent years, the supramolecular self-assembly systems based on second-sphere coordination have gained a wide application in host-guest molecule recognition, extraction and separation of precious metals and catalysts. Second sphere coordination has been applied in the design and study in areas as diverse as separation, gas adsorption, and light emitting properties. However,the solid-state reactivity based on second-sphere coordination has been rarely studied,which needs an in-depth study. Based on this, the following work has been carried out in this paper.Herein we sythsized a bidentate ligand, ?±?-trans-N, N'-Dibenzyl-l,^2-diaminocyclohexane ?L?. Upon self-assembling, L can be reacted with different metal chloride compounds to form second sphere adducts [H2L] · [CuCl₄]^2- ?crystal 1?,[H2L]²⁺·[ZnCl₄]^2-?crystal 2? and the complexs [?CUCl₂??L?] ?crystal 1'?,[?ZnCl₂??L?] ?crystal 2'?. These second sphere sddacts can also be synthesized in the solid state with directly grinding L and CuCl₂ or ZnCl₂ with the addition of concentrated hydrochloric acid and a drop of solvent.The solid-state conversion of the metal-organic hybrid salts and their coordination complexes were studied. Upon grinding salt 1 and 2 with KOH with the addition one drop of methanol for about 5 minutes,or upon heating, the addacts 1 and 2 released HCl gas and transformed to the neutral metal coordination complex[?CUCl₂??L?] ?complex 1'? and [?ZnCl₂??L?] ?complex 2'?. Meanwhile,once the powder of complexes 1' and 2' were put in the atmosphere of the solvent and hydrochloric acid separately, they transformed back to second sphere adducts in the solid state .In addition, the organic ligand of ?±?-trans-N,N'-Dibenzyl-1,2-diaminocyclohexane ?L? and other metal complexes were reactd to get H2O[H2L]²⁺·[CdCl₄]^2- crystal 3, H2O ??? [H2L]²⁺· [CoCl₄]^2- crystal 4,EtOH???LH2L]·[CuCl₄]^2- crystal 5. These crystals structure and solid fluorescence were investigated.