A Family of Uranyl Coordination Polymers Containing O‑Donor Dicarboxylates and Trispyridyltriazine Guests

Four uranyl coordination polymers
[UO2(C6H8O4)­(H2O)2]­(C18H12N6)2 (1),
[UO2(C8H4O4)­(H2O)2]­(C18H12N6)2 (2), Na­[(UO2)­(C12H6O4)2]­(C18H13N6)­·H2O (3),
and Na­[(UO2)­(C16H8O4)­(C6H3NO2)]­(C18H12N6)­·H2O (4) containing aliphatic (adipic acid) or aromatic linkers (1,4-benzene
dicarboxylic acid (BDC), 1,4-napthalene dicarboxylic acid (NDC), anthracene
9,10-dicarboxylic acid (ADC)) were synthesized and characterized using
single crystal X-ray diffraction, powder X-ray diffraction, and luminescence
spectroscopy. The π-stacking distances or the number of π–π
interactions present between trispyridyltriazine (TPTZ) guests or
the host framework in 1–4 may be
affected by the size of the O-donor linker (adipic acid < BDC <
NDC < ADC). Luminescence studies show that substitution between
adipic acid and BDC influences the emission of 1 and 2, in which the emission of 1 shows a red shift
relative to that of 2. Uranyl emission was not observed
in 3 and 4, and may be attributed to the
position of the NDC and ADC triplet state relative to the emissive
uranyl species.