Anion controlled supramolecular self-assembly of tetraprotonated tris[2-(benzylamino)ethyl]amine

The novel supramolecular assembly of composition [{(bz(3)tren)H-4}(4+) (.) (ReO4)(-) (.) 3(Cl)(-)] resulted from the self-organization of a mixture of tris[2-(benzylamino)ethyl]amine (bz(3)tren), HCl and NH4ReO4 at a molar ratio of 1:4.7:1 in methanol. The crystal architecture is characterized by stacks of repeating sandwich-type building blocks that contain charge-assisted N-(HO)-O-...(Re) hydrogen bonds [(NO)-O-... 2.81-2.86 Angstrom] and weaker C-(HO)-O-...(Re) interactions [(CO)-O-... 3.11 Angstrom]. The stacks are further linked by N-(HCl)-Cl-...[(NCl)-Cl-... 3.03 Angstrom] and weaker C-(HCl)-Cl-...[(CCl)-Cl-... 3.47-3.74 Angstrom] interactions into two-dimensional layers bordered by the benzyl groups of the [(bz(3)tren)H-4](4+) cations. Edge-to-face C-H(...)pi interactions involving the aromatic rings occur within and between the layers. The protonation constants of bz(3)tren in methanol were determined by potentiometric titration. The corresponding structures of the ligand in its different protonation states were calculated at the DFT-level.