Remarkable near-infrared chiroptical properties of chiral Yb, Tm and Er complexes

Abstract

We carried out a study of absorption (CD) and emission (CPL) chiroptical properties in the NIR region of two sets of Yb, Tm and Er complexes. The two complexes include a D₃ symmetric, [TMG-H⁺]₃Ln(BINOLate)₃ (Ln = Yb, Tm, Er; TMG = 1,1,3,3-tetramethylguanidine; BINOLate = 1,1′-bi-2-naphtholate), and a tetrakis, C₄ symmetric, CsLn(hfbc)₄ (Ln = Yb, Tm, Er; hfbc = 3-heptafluorobutylyrylcamphorate). The lanthanides studied gave access to three discrete energy domains, Yb (900–1040 nm), Tm (1180–1240 nm) and Er (1430–1600 nm) in which the chiroptical activity was assessed using g_abs (and g_lum for Yb complexes). Exceptionally high discrimination between left and right circularly polarised light was observed, with values up to almost the theoretical maximum (±2).