Near-Infrared Lanthanide-Based Emission from Fused Bis[Ln(III)/Zn(II) 14-metallacrown-5] Coordination Compounds.

A set of (Ln[14-MC Zn(II)N(quinHA) -5]) 2 Ln 2 Zn 2 (quinHA) 2 (ph) 2 (Hph) 4 (OH) 8 (H 2 O) 4 metallacrowns ( Ln-1 , Ln = Tb, Gd, or Yb; H 2 quinHA = quinaldic hydroxamic acid, H 2 ph = phthalic acid) have been synthesized via solution-state self-assembly. The metallacrowns possess an uncommon topology within the metallacrown family where two rarely seen 14-metallacrown-5 moieties are fused by a Yb 2 Zn 2 (quinHA) 2 bridge. Moreover, Yb-1 analyzed in the solid state exhibits a characteristic near-infrared luminescence signal arising from Yb 3+ 2 F 5/2 → 2 F 7/2 transition despite the proximity of high energy O-H oscillators.