Luminescence thermometry and field induced slow magnetic relaxation based on a near infrared emissive heterometallic complex.

The 1 : 1 : 1 reaction of YbCl 3 ·6H 2 O, K 3 [Co(CN) 6 ] and bpyO 2 in H 2 O has provided access to a complex with formula [YbCo(CN) 6 (bpyO 2 ) 2 (H 2 O) 3 ]·4H 2 O (1) in a very good yield while its structure has been determined by single-crystal X-ray crystallography and characterised based on elemental analyses and IR spectra. Magnetic susceptibility studies showed the complex to be a field induced single molecule magnet, as confirmed by μ-SQUID measurements. CASSCF calculations confirm the existence of a m J = 7/2 ground state, with rather large transverse components, responsible for the fast relaxation characteristic of compound 1 at zero DC field, which is reduced upon application of DC fields. Moreover, a combination of luminescence studies along with CASSCF calculation allows the identification of the band structure of the complex, which is ultimately related to its electronic properties. Compound 1 operates as a luminescent thermometer in the 125-300 K range with a maximum relative thermal sensitivity of ≈0.1% K -1 at 180 K.