Chih-Yuan Chen

Anion-π interaction stitching 2-D layers formed by self-assembly of cations of a mononuclear copper(II) complex: synthesis, crystal structure and magnetism of [Cu(OAc)(2,2′-dypam)2](ClO4) [HOAc = acetic acid, 2,2′-dypam = 2,2′-dipyridylamine]

A mononuclear Cu(II) compound [Cu(OAc)(2,2′-dypam)2](ClO4) (1), where HOAc and 2,2′-dypam are, respectively, acetic acid and 2,2′-dipyridylamine, has been synthesized and characterized by single crystal X-ray diffraction analysis. The cations of 1 link by N–H ··· O hydrogen bonds to form infinite 1-D zig-zag chains, which run along the b axis. Two adjacent chains along the c axis are joined by C–H ··· O hydrogen bonds to form a 2-D network. These 2-D layers are further bridged by perchlorate anions via weak anion-π interactions that act as a supramolecular glue to build the 3-D supramolecular network. Variable temperature (1.7–300 K) magnetic measurements revealed very weak intermolecular antiferromagnetic interactions at temperatures below 20 K between Cu(II) ions mediated by hydrogen bonds, C–H ··· π and π ··· π interactions. At temperatures ≥20 K, susceptibility data corresponds to isolated Cu(II) ions, indicating that the weak interactions affect the magnetism of 1 only at very low temperatures.

Controlled assembly of an unprecedented 2D + 3D interpenetrated array of (4,4)-connected and pcu topologies

We achieved the truly ‘engineered’ 2D + 3D interpenetrated array of (4,4)-connected + pcu nets. This fascinating interpenetrated array has remained unknown since its prediction was made about ten years ago. The successful construction was based on the introduction of a large flat anthracene group in the organic linker that effectively manipulates interpenetration.

pH-triggered changes in the supramolecular self-assembly of Cu(II) malonate complexes

Two different hydrate phases, namely, {[Cu(mal)2](picH)2·2H2O}n (1) and {[Cu(mal)2](picH)2·5H2O}n (2) [malH2 = malonic acid; picH = protonated 2-amino-4-picoline] could be synthesized from purely aqueous media simply by mixing the reactants in stoichiometric ratio but with a slight alteration in the acidity of the reaction media. When the solid-state structure of 1 is compared with the previously reported complex 2, interesting changes in the supramolecular self-assembly are noticed. We found that the observed pH-triggered change is exclusive in the ternary system stated and not for Ni(II), Co(II) or Mn(II). We also noticed the presence of a –CH3⋯Ow interaction between the methyl terminals of protonated picoline molecules and the oxygen atoms of lattice water molecules in 1.