Rational design of MOFs constructed from modified aromatic amino acids

Three Phe and Tyr derivatives, 2-amino-3-(4-aminophenyl)-propionic acid (AAP), 3E-[5-(2-amino-2-carboxyethyl)-2-methoxyphenyl]-acrylic acid (AMPA) and 3-(4-aminophenyl)-2-(carboxymethyl-amino)-propionic acid (ACP) have been chosen as the ligands to construct four kinds of novel metal-organic frameworks (MOFs) (five structures). These structures are, [Cd^II{(R)-AAP}(Py)(H ₂O)]·(ClO₄), (R)-1; [Cd^II{(S)-AAP} (H₂O)₂]·(ClO₄), (S)-2; [Zn ₂^II{(R,S)-AMPA}(H₂O)], (R,S)-3; [Zn ₂^II{(R)-ACP)(Py)₃]·(ClO ₄)₂, (R)-4; and the inversion twin of (R)-1. Rational design to adjust the "depth" and the "width" of ligands can mediate the size and the shape of the grids of these 2D layers. Additionly, among these compounds, three pure chiral coordination polymers are obtained, owing to the inducement of chirality by the modified amino acids. This property makes them potential NLO materials.