Near-Infrared Emitting Chiral Tetranuclear Erbium Cluster Containing Soft-Base Bisthiazolate Linkers

A tetraerbium cluster containing soft-base dianionic 4,8-difluorobenzo [1,2-d:5,4-d′]bisthiazole-2,6-dithiol (H2L) ligands, μ-OH, and coordinated 1,2-dimethoxyethane (DME) of the general formula {Er4(μ-L)4(μ-OH)4(DME)4} (1) was synthesized using a one-pot method. X-ray analysis revealed that 1 is an asymmetrical tetramer in which there are four μ2-bridging bisthiazole ligands and four μ2-bridging hydroxide anions per four erbium ions. The molecule of 1 has inherent chirality, and the geometry of intramolecular F…F short contacts implies the formation of a classical halogen bond. Upon excitation by a 375 nm diode laser, compound 1 shows the moderate metal-centered emission of Er3+ ions that peaked at 1530 nm.