Lanthanide Ions in Molecular Exchange Coupled Systems

A series of isostructural open-framework coordination polymers formulated as [Ln(dmf)(3)(ptmtc)] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5); PTMTC = polychlorotriphenylmethyl tricarboxylate) and [Ln(dmf)(2)H(2)O(αH-ptmtc)] (Ln = Sm (1'), Eu (2'), Gd (3'), Tb (4'), Dy (5')) have been obtained by treating Ln(III) ions with PTMTC ligands with a radical (PTMTC(3-)) or a closed-shell character (αH-PTMTC(3-)). X-ray diffraction analyses reveal that these coordination polymers possess 3D architectures that combine large channels and fairly rare lattice complex T connectivity. In addition, these compounds show selective framework dynamic sorption properties. For both classes of ligands, the ability to act as an antenna in Ln sensitization processes has been investigated. No luminescence was observed for compounds 1-5, and 3' because of the PTMTC(3-) ligand and/or Gd(III) ion characteristics. Conversely, photoluminescence measurements show that 1', 2', 4', and 5' emit dark orange, red, green, and dark cyan metal-centered luminescence. The magnetic properties of all of these compounds have been investigated. The nature of the {Ln-radical} exchange interaction in these compounds has been assessed by comparing the behavior of the radical-based coordination polymers 1-5 with those of the compounds with the diamagnetic ligand set. While antiferromagnetic {Sm-radical} interactions are found in 1, ferromagnetic {Ln-radical} interactions propagate in the 3D architectures of 3, 4, and 5 (Ln = Gd, Tb, and Dy, respectively). This procedure also provided access to information on the {Ln-Ln} exchange existing in these magnetic systems.

Section: Magnetic Propertiessupporting

confidence: 67%

Section: àmentioning

confidence: 99%

Section: àmentioning

confidence: 99%

See 1 more Smart Citation

Three‐Dimensional Open‐Frameworks Based on Ln^IIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties

Datcu

Roques

Jubera

et al. 2011

“…The slight decrease of the c M T product between 300 and 41.8 K is owed to the depopulation of the Stark levels of the dysprosiumA C H T U N G T R E N N U N G (III). [17] The increase of c M T below 40 K is associated with an intranode ferromagnetic interaction between Cu II and Dy III , as observed with other compounds containing these two ions. [5r, 18] The field dependence of the magnetization recorded at 2 K for 2 (Figure 2, bottom) exhibits a sigmoid shape and remains below the anticipated saturation value.…”

mentioning

confidence: 93%

First Heterotrimetallic {3 d‐4 d‐4 f} Single Chain Magnet, Constructed from Anisotropic High‐Spin Heterometallic Nodes and Paramagnetic Spacers

Visinescu

Mădălan

Andruh

et al. 2009

Self Cite

208

115

Dedicated to Dr. Jean-Pierre Costes as a tribute to his contributions to the development of the chemistry and magnetism of 3d-4f complexesPolymetallic complexes are more and more involved in materials science. The metal ions exert a functional role, carrying magnetic, optical, or redox properties, and a structural one, directing and sustaining the overall architecture of the polymetallic systems. The use of different metal ions in constructing coordination compounds brings novel properties that are not exhibited by the homometallic complexes. [1] Since the first report on the Cu II À Gd III ferromagnetic interaction, [2] the 3d-4f combined chemistry attracted much attention, aiming, in a first stage, to obtain "classical" (3D) molecule-based magnets.[3] The results were rather disappointing: the critical temperatures for the molecular magnets constructed from Cu II and Gd III ions were found to be very low.[4] More recently, the interest of chemists moved towards lanthanides exhibiting a high anisotropy, which is a prerequisite for designing single molecule magnets (SMMs) and single chain magnets (SCMs). The best candidates for this purpose are terbiumA C H T U N G T R E N N U N G (III), dysprosiumA C H T U N G T R E N N U N G (III) and holmium-A C H T U N G T R E N N U N G (III). Indeed, several SMMs, [5] and SCMs, [6] based upon 3d and 4f (Tb III , Dy III , Ho III ) ions, were reported recently. Moreover, it has been shown that even mononuclear Tb III and Dy III complexes fulfil the necessary conditions to exhibit slow relaxation of the magnetization. [7] A plethora of polynuclear complexes with interesting magnetic properties are constructed from two different paramagnetic metal ions (3d-3d', 3d-4d, 3d-5d, 3d-4f, 4d-4f, 5d-4f), while the number of heterotrimetallics is much more limited. Only few 3d-3d'-4f complexes are reported to date.[8] The main problem the chemist is faced with is to obtain pure products in high yield, by avoiding the scrambling of the three different metal ions. A successful synthetic approach consists of self-assembly processes involving preformed 3d-4f oligonuclear cationic complexes and stable metal-containing anions with potentially bridging ligands, for example hexacyanometallates, [M(CN) 6 ] 3À . We have recently shown that bi-and trinuclear 3d-4f species {(CuL) n Ln} (n = 1, 2; L 2À = a dissymetric compartmental Schiff-base ligand) can efficiently act as tectons in designing both high-nuclearity clusters and coordination polymers with various dimensionalities and network topologies.[9] Fol-[a] Dr.

“…At 2 K, a value of 8.43 cm 3 K mol À1 is observed for this compound. In the case of 2 (Figure 7, middle), the c M (2)T values remain close to 8.40 cm 3 K mol À1 between 300 and 10 K, and then diminish slightly to reach a value of 7.03 cm 3 K mol À1 at 2 K. For 3, the c M (3)T curve is characterized by a continuous decrease as the temperature is lowered, with a sharper decrease below 10 K to afford a c M (3)T value of 0.25 cm 3 K mol À1 at 2 K. These magnetic behaviors can be ascribed to a combination of the intrinsic characteristics of Ln ions, [53] and to potential {Ln-Ln}, {Ln-radical} and/or {radical-radical} interactions. For Eu III ions, excited states resulting from spinorbit coupling are close enough to the ground state to be thermally populated at room temperature.…”

Section: Magnetic Propertiesmentioning

confidence: 96%

Three‐Dimensional Porous Metal–Radical Frameworks Based on Triphenylmethyl Radicals

Datcu

Roques

Jubera

et al. 2011

Self Cite

Lanthanide coordination polymers {[Ln(PTMTC)(EtOH)(2)H(2)O]·x H(2)O, y EtOH} [Ln=Tb (1), Gd (2), and Eu (3)] and {[Ln(αH-PTMTC)(EtOH)(2)H(2)O]·x H(2)O, y EtOH} [Ln=Tb (1'), Gd (2'), and Eu (3')] have been prepared by reacting Ln(III) ions with tricarboxylate-perchlorotriphenylmethyl/methane ligands that have a radical (PTMTC(3-)) or closed-shell (αH-PTMTC(3-)) character, respectively. X-ray diffraction analyses reveal 3D architectures that combine helical 1D channels and a fairly rare (6,3) connectivity described with the (4(2).8)·(4(4).6(2).8(5).10(4)) Schäfli symbol. Such 3D architectures make these polymers porous solids upon departure of the non-coordinated guest-solvent molecules as confirmed by the XRD structure of the guest-free [Tb(PTMTC)(EtOH)(2)H(2)O] and [Tb(αH-PTMTC)(EtOH)(2)H(2)O] materials. Accessible voids represent 40% of the cell volume. Metal-centered luminescence was observed in Tb(III) and Eu(III) coordination polymers 1' and 3', although the Ln(III)-ion luminescence was quenched when radical ligands were involved. The magnetic properties of all these compounds were investigated, and the nature of the {Ln-radical} (in 1 and 2) and the {radical-radical} exchange interactions (in 3) were assessed by comparing the behaviors for the radical-based coordination polymers 1-3 with those of the compounds with the diamagnetic ligand set. Whilst antiferromagnetic {radical-radical} interactions were found in 3, ferromagnetic {Ln-radical} interactions propagated in the 3D architectures of 1 and 2.