Crystal Engineering with the Uranyl Cation II. Mixed Aliphatic Carboxylate/Aromatic Pyridyl Coordination Polymers: Synthesis, Crystal Structures, and Sensitized Luminescence

Eleven novel U(VI)-containing coordination polymers have been synthesized under hydrothermal conditions and
characterized via single-crystal X-ray diffraction and fluorescence spectroscopy. These inorganic/organic hybrid materials represent
an important advance in the synthesis of polymeric materials in that multiple organic species have been employed in an effort to
influence topology and properties. This family of materials is thus the result of a systematic pairing of the uranyl cation, UO22+,
with aliphatic dicarboxylates (see part I, this issue) and the dipyridyl species, 4,4‘-dipyridyl and 1,2-bis(4-pyridyl)ethane. This second
organic component assumes a number of roles in these structures, including direct coordination, charge balance, and structure direction.
Distinction between which role(s) the dipyridyl species will assume appears to be correlated to the size (length) matching between
it and the dicarboxylate linker used. Further, polymerization of primary building units (i.e., monomeric uranyl species) to form
novel tetrameric secondary building units is observed in four compounds, possibly as a compensation for size differential between
the organic species.