title: Cu(II)-Gd(III) cryogenic magnetic refrigerants and Cu8Dy9 single-molecule magnet generated by in situ reactions of picolinaldehyde and acetylpyridine: experimental and theoretical study.
abstract: A series of heterometallic [Ln(III)(x)Cu(II)(y)] complexes, [Gd2Cu2]n (1), [Gd4Cu8] (2), [Ln9Cu8] (Ln=Gd, 3·Gd; Ln=Dy, 3·Dy), were successfully synthesized by a one-pot route at room temperature with three kinds of in situ carbonyl-related reactions: Cannizzaro reaction, aldol reaction, and oxidation. This strategy led to dysprosium analogues that behaved as single-molecule magnets (SMMs) and gadolinium analogues that showed significant magnetocaloric effect (MCE). In this study a numerical DFT approach is proposed by using pseudopotentials to calculate the exchange coupling constants in three polynuclear [Gd(x)Cu(y)] complexes; with these values exact diagonalization or quantum Monte Carlo simulations have been performed to calculate the variation of the magnetic entropy involved in the MCE. For the [Dy9Cu8] complexes, local magnetic properties of the Dy(III) centers have been determined by using the CASSCF+RASSI method.
authors.affiliation: Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, State Key Laboratory of Optoelectronic, Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (P.R. China).
authors.forename: Jun-Liang
authors.initials: JL
authors.lastname: Liu
authors.forename: Wei-Quan
authors.initials: WQ
authors.lastname: Lin
authors.forename: Yan-Cong
authors.initials: YC
authors.lastname: Chen
authors.forename: Silvia
authors.initials: S
authors.lastname: Gómez-Coca
authors.forename: Daniel
authors.initials: D
authors.lastname: Aravena
authors.forename: Eliseo
authors.initials: E
authors.lastname: Ruiz
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Leng
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Tong
keywords: 3d-4f complexes; CASSCF calculations; density functional calculations; magnetocaloric effect; single-molecule magnets