Manganese(II) and zinc(II) compounds via amino acid derivatives: Effects of temperature and solvents

To investigate the influence of temperature and the ratios of solvents on the design and synthesis of metal–organic frameworks (MOFs), we have synthesized and structurally characterized a series of supramolecular assemblies based on different amino acid derivatives and nitrogen-containing heterocyclic ligands, namely [Mn(phen)2(phth)(H2O)]·4H2O (1), [Mn(phen)2(HL1)2]·3.5H2O (2), [Zn(bpp)2(L-Me)2] (3), and [Zn(bpp)(L-Me)2] (4) (H2phth = phthalic acid, H2L1 = phthalyl-l-valine, H2L = (+)-N-tosyl-l-glutamic acid, phen = 1,10-phenanthroline, bpp = 1,3-bis(4-pyridyl)propane, and L-Me = C12H13NO6S–CH3). Compounds 1 and 2, which are assembled through noncovalent interactions, were obtained by controlling the temperature. In 1, π–π stacking and hydrogen-bonding interactions lead to stacking in a 3D supramolecular network, while in 2, π–π stacking interactions form 1D chains that extend along the c-axis. Depending on the solvents employed, compounds 3 and 4 could be generated, with a 1D bpp-connected Zn–bpp–Zn double chain that is further hydrogen-bonded into a 2D network that extends parallel to the ac plane in 3, and a single chain in 4.