Synthesis, crystal structure, magnetic and luminescence investigations of new 2Ln3+–Sr2+ heteronuclear polymers with 2-furoic acid

New first examples of complexes with the general formula {[Ln2Sr(C4H3OCOO)8(H2O)4]}n, where Ln = La3+ (1), Pr3+ (2), Nd3+ (3), Sm3+ (4), Eu3+ (5), Gd3+ (6), Tb3+ (7), Ho3+ (8), Yb3+ (9) and Er3+ (10) have been prepared and investigated by photoluminescence spectroscopy and magnetic susceptibility measurements. The X-ray crystal structure has been determined for the {[Er2Sr(C4H3OCOO)8(H2O)4]}n (10) complex, indicating that this complex is built from two crystallographic independent coordination polymers {[Er2Sr(C4H3OCOO)8(H2O)4]}n in the triclinic crystal system and P1 space group. The X-ray diffraction (XRD) pattern of the samples shows that all lanthanide compounds are isostructural to 10. The luminescence spectrum of a microcrystalline sample of “2Eu–Sr” compound displays the characteristic Eu3+ (5D0 → 7FJ (J = 0–4)) metal centred transitions; also “2Nd–Sr” proved to be luminescent in the near IR. Measurements of the magnetic susceptibility for 2, 3, 5 and 10 were described using Crystal Field approach.