A new family of two-dimensional lanthanide(III) coordination polymers: synthesis, structures and properties of [Ln(SIP)(H2O)4]n (Ln=Eu, Gd, Ce, and NaH2SIP=5-sulfoisophthalic acid monosodium salt)

A new family of lanthanide coordination polymers with the general formula [Ln(SIP)(H2O)4]n (Ln=Eu, Gd, Ce, 1–3; and NaH2SIP=5-sulfoisophthalic acid monosodium salt) was hydrothermally synthesized and characterized by IR, elemental analysis, single-crystal X-ray crystallography and powder X-ray diffractions. X-ray studies indicated that these compounds are isostructural and adopt an electrically neutral and undulating two-dimensional layer structure constructed from fused {[Eu(H2O)4]3(SIP)3} pseudo-hexagonal grids. Thermogravimetric measurements in N2 revealed that all exhibit weight losses corresponding to four water molecules per formula unit around 120 °C and the dehydrated compounds are stable up to ca 510 °C. The fluorescence spectrum showed that [Eu(SIP)(H2O)4]n displays intense red fluorescence in the solid-state. The paramagnetism for [Gd(SIP)(H2O)4]n in the range 5–300 K reveals no magnetic coupling via SIP ligand.