you want to react the amine of each diamine with different aldehydes?

Imines are not extremely stable compounds without an aromatic group to stabilise. without more information very hard to provide any advice

Yes I want to react the amine of each diamine with different aldehydes.

Diamines which I use almost have an aromatic group such as o-phenylenediamine except maleonitrile moeity. Although diamines have an aromatic ring you said, replacing other aldehyde is more often reaction. How should I do??

http://www.organic-chemistry.org/synthesis/C2N/imines.shtm

you can check this link for more methods to synthesise imines. 

Without knowing the exact structure it is difficult to say why the second imine reaction does not occur.

I want to synthesis these asymetric imine.

One imine easily synthesized in MeOH or EtOH without catalyst.

However, next step imine reaction is so difficult.

Reaction is very fast. As soon as another aldehyde is put in flask but the result is just one-side subsituted imine.

Could you give me an advice? I'll wailt your answer. Thanks

Dear Rafael Arcos-Ramos

Thank you for many references.

I think metal templating is suitable synthesis method. Then, if I synthesized these asymetric imine complexes, can I remove metal ions  in them through EDTA or other chelating agent? Because I want to use ligand without complexes!