NIR luminescence of 2-(2′-hydroxyphenyl)benzimidazole lanthanide (Ln=Nd and Yb) complexes

Reactions of 2-(2′-hydroxyphenyl)benzimidazole (HL) with Nd(NO3)3 ⋅ 6H2O and YbCl3 ⋅ 6H2O affords two lanthanide complexes [H2L]2[Nd(HL)2(NO3)4]2 ⋅ 2CH3OH ⋅ 2H2O (1) and [H2L][Yb(HL)2Cl4] ⋅ 2CH3OH (2), respectively. X-ray crystallographic analysis reveals that the two crystallographically distinct Nd3+ ions are ten-coordinated to two O atoms from two ligands and eight O atoms from four bidentate nitrate groups in 1. In the case of 2, the crystallographically distinct Yb3+ ion is hexa-coordinated to four Cl− ions and two O atoms in an octahedral geometry. Structural analysis indicates the importance of H-bondings and π–π stacking in the construction of 1 and 2. Complexes 1 and 2 exhibit essential NIR luminescence of Nd3+ and Yb3+ ions, respectively.