Use of π-π forces to steer the assembly of a NTA complex of Cu(II) into hydrogen bonded supramolecular layers (H3NTA = nitrilotriacetic acid)

We propose a crystal engineering principle where we show that it might be possible to direct the organization of molecular complexes into hydrogen bonded supramolecular layers through the use of suitable co-ligands possessing both the hydrogen-bonding as well as π-π stacking capability. This principle has been tested for the organization of [Cu(NTA)2] units (H3NTA = nitrilotriacetic acid, N(CH2CO2H)3) in the molecular complex with formula (2-A-PH)4[Cu(NTA)2]·6H2O (1), where 2-A-PH is protonated 2-amino-4-picoline. In 1, the 2-amino-4-picoline co-ligands have been utilized to direct the organization of [Cu(NTA)2] units into hydrogen bonded layers. The linear stacking of π-π bonded protonated 2-amino-4-picoline molecules can be thought as the influencing agent for the organization of [Cu(NTA)2] units into hydrogen bonded layers.