Building 1D lanthanide chains and non-symmetrical [Ln2] "triple-decker" clusters using salen-type ligands: magnetic cooling and relaxation phenomena. Issue 46 (9th November 2016)

• Record Type: Journal Article
• Authors: Canaj, Angelos B.; Siczek, Milosz; Otręba, Marta; Lis, Tadeusz; Lorusso, Giulia; Evangelisti, Marco; Milios, Constantinos J.
• Is Part Of: Dalton transactions. Volume 45:Issue 46(2016)
• Page Start: 18591
• Page End: 18602
• Publication Date: 2016-11-09
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6dt02932a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Three series of related lanthanide polymers/dimers have been structurally and magnetically investigated. Abstract : A solvothermal reaction between Ln(NO3 )3 ·6H2 O (Ln: Gd, Tb and Dy), 2-hydroxy-1-naphthaldehyde, 2-OH-naphth, and ethylenediamine, en, in MeOH in the presence of a base, NEt3, led to the formation of the 1D coordination polymers [Ln(L)(MeO)(MeOH)0.5 ] n ·MeOH (Ln = Gd (1 ·MeOH), Tb(2 ), Dy (3 ·MeOH); H2 L = 1, 1′-((1 E, 1′ E )-(ethane-1, 2-diylbis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol), the Schiff-base ligand derived from the condensation of 2-OH-naphth and en), while a similar reaction in an excess of NaN3 yielded 1D coordination polymers [Ln(L)(N3 )0.75 (MeO)0.25 (MeOH)] n (Ln = Gd (4 ), Tb (5 ), Dy (6 )). Finally, upon replacing ethylenediamine with o -phenylenediamine, o -phen, we managed to isolate the discrete dimers [Dy2 (L′)3 (MeOH)]·2MeOH (7 ·2MeOH) and [Gd2 (L′)3 (MeOH)]·2MeOH (8 ·2MeOH) (H2 L′ = 1, 1′-((1 E, 1′ E )-(1, 2-phenylenebis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol), the Schiff-base ligand from the condensation of 2-OH-naphth and o -phen). Polymers1–3 describe one-dimensional chains, containing alternating seven- and eight-coordinate Ln III metal centers, polymers4–6 contain eight-coordinate lanthanide ions, while in both7 and8 the two Ln III centers are eight- and seven-coordinate, adopting square antiprismatic and "piano-stool" geometry, respectively. The magnetocaloric properties of the three Gd III analogues were determined from magnetic measurements, yielding the magnetic entropy change –Δ S m = 21.8, 23.0 and 16.0 J kg −1 K −1 at T = 3.0 K on demagnetization of 7 T to 0, for1, 4 and8, respectively. The study of the magnetic properties also revealed that all three Dy III analogues (3, 6 and7 ) display out-of-phase signals, therefore suggesting slow magnetic relaxation, while such behaviour was not established in the Tb III analogues.