We have continued to pursue MOFs built upon supramolecular secondary building units (see the 2006 report) and synthesized two new isostructural 3D MOFs assembled from infinite 1D secondary building units.  These MOFs are supported by anions of the ditopic 1,4-cyclohexanedicarboxylic acid (H₂CDC) and are formulated empirically as [La₃(H₂O)₂(CDC)_3.5(HCDC)₂]·H₂O (Ln = La, Ce).

We have also started a new direction of research, that is, the assembly of MOFs containing light main-group metal ions such as Mg²⁺, Ca²⁺, and Al³⁺.  A potential application of MOFs is in adsorbing and storing hydrogen gas.  Use of such light metal ions in place of transition metal or lanthanide ions can reduce densities of MOFs and therefore improve the hydrogen storage capacity of MOFs as measured by the weight of H₂ adsorbed as a percentage of the weight of the MOF adsorbent.  The synthesis of such MOFs involves ditopic carboxylates as anionic ligands to support charge-neutral and robust coordination frameworks with light metal ions as nodes.  The ditopic acids include phenylenediacetic acid (H₂PDA) and (4'-carboxymethyl-biphenyl-4-yl)-acetic acid (H₂BPA).  Solvothermal reactions of these acids with Mg²⁺, Ca²⁺, and Al³⁺ salts lead to solids that appear to be polymeric carboxylates, as judged from their FTIR spectra and their insoluble nature in water or organic solvents.  We are attempting to make single crystals that are of X-ray diffraction quality for structural characterization.