A Nd6 molecular butterfly: a unique all-in-one material for SMM, MCE and maiden photosensitized opto-electronic device fabrication

Layered lanthanide phosphonates Ln(2-qpH)(SO4)(H2O)2 (Ln = La, Ce, Pr, Nd, Sm): polymorphism and magnetic properties

Polymorphic layered lanthanide coordination polymers provide opportunities to study the effect of intralayer and interlayer interactions on their magnetic dynamics. Herein we report a series of layered lanthanide phosphonates, namely, α-Ln(2-qpH)(SO4)(H2O)2 (Ln = Sm) (α-Ln), β-Ln(2-qpH)(SO4)(H2O)2 (Ln = Pr, Nd, Sm) (β-Ln) and γ-Ln(2-qpH)(SO4)(H2O)2 (Ln = La, Ce, Pr, Nd, Sm) (γ-Ln) (2-qpH2 = 2-quinolinephosphonic acid), which crystallize in monoclinic P21/c (α-Ln), triclinic P1̄ (β-Ln) and orthorhombic Pbca (γ-Ln) space groups, respectively. The structural differences between the β- and γ-phases lie not only in the intralayer but also in the interlayer. Within the layers, the Ln2O2 dimers are aligned parallel in the β-phase, but are non-parallel in the γ-phase. In the interlayer, there are π-π interactions between the quinoline groups in the α- and β-phases but not in the γ-phase. Magnetic studies reveal a field-induced slow relaxation of the magnetisation at low temperatures for compounds γ-Ce, β-Nd, and γ-Nd, and the impact of polymorphism on the magnetic dynamics of Nd(III) compounds is discussed.

A Silver-Based Integrated System Showing Mutually Inclusive Super Protonic Conductivity and Photoswitching Behavior

Photoinduced electricity and proton conductivity led fuel cells have emerged, inter alia, as highly promising systems for unconventional energy harvesting. Notwithstanding their individual presence with widely acclaimed results, an integrating system with mutually inclusive manifestation of both features has hitherto not been reported in the literature. To achieve this objective, our approach was to design a ligand system incorporating prerequisite features of both systems, like extended conjugation instigating photophysical activity and functional groups facilitating ionic conduction. As such, we report herein the design, synthesis, and characterization of a pyridyl-pyrazole-based silver compound that exhibits an excellent photocurrent generation and very high proton conductivity. The X-ray single-crystal structure of the Ag complex fully supports our notion, showing extensive π-π conjugated aromatic rings with a protruding free sulfonic group, facing toward solvent-filled channels with numerous supramolecular interactions. The nanoscopic silver metallogel induces semiconductive features in the system which ultimately result in photoresponse behavior in terms of photocurrent generation with an whopping photocurrent gain (I_on/I_off) of 21.2. To complete the idea of an integrated system, the proton conductivity values were also measured for both gel and crystalline states, while the former state yields a better result. The maximum proton conductivity value turns out to be 1.03 × 10^-2 S cm^-1 at 70 °C, which is higher than or comparable to those of well-known systems in the literature for proton conductivity.

A single-ion magnet building block strategy toward Dy2 single-molecule magnets with enhanced magnetic performance

A molecular dysprosium(III) complex [Dy(DClQ)₃(H₂O)₂] (1) was used as a building unit for the construction of lanthanide SMMs, leading to the isolation of two dinuclear Dy(III) complexes, namely [Dy₂(DClQ)₆(MeOH)₂] (2) and [Dy₂(DClQ)₆(bpmo)₂]·6MeCN (3) (DClQ = 5,7-dichloro-8-hydroxyquinoline, bpmo = 4,4'-dipyridine-oxide). Structural analyses revealed the same N₃O₅ coordination environment of the Dy(III) centers with a distorted biaugmented trigonal prism (C_2V symmetry) and triangular dodecahedron (D_2d symmetry) for 2 and 3, respectively. Magnetic studies revealed the presence of ferromagnetic and weak antiferromagnetic exchange interactions between the Dy³⁺ centers in 2 and 3, respectively. Interestingly, slow relaxation of magnetization at zero fields was evidenced with an U_eff of 51.4 K and 159.0 K for complexes 2 and 3, respectively. The detailed analysis of relaxation dynamics discloses that the Orbach process is dominant for 2 whereas Raman and QTM play an important role in 3. Theoretical calculations were carried out to provide insight into the magnetic exchange interactions and relaxation dynamics for the complexes. Due to a single-ion magnet (SIM) of 1, the foregoing results demonstrate a SIM modular synthetic route for the preparation of dinuclear lanthanide SMMs.

Oxalate-bridging NdIII-based arsenotungstate with multifunctional NIR-luminescence and magnetic properties

Oxalate bridged Nd-based arsenotungstate, K₁₄Na₆H₄[{(As₂W₁₉O₆₇(H₂O))Nd(H₂O)₂}₂(C₂O₄)]·64H₂O (1), was obtained from the reaction of K₁₄[As₂W₁₉O₆₇(H₂O)], oxalic acid, and NdCl₃·6H₂O in mildly acidic aqueous solution. The polyanion exhibits a dimeric structure in which the fully deprotonated oxalate ligands bridge two Nd^III cations and the arsenotungstate anions act as blocking ligands. The photoluminescence (PL) spectrum of 1 shows the characteristic emission peak of Nd^III in the near-infrared (NIR) region. However, the O → W charge-transfer transitions of arsenotungstate cannot effectively sensitize the emission of Nd^III cations as confirmed by the emission spectrum, due to the mismatch of the energy gap between ³T_1u → ¹A_1g (21.57 × 10³ cm^-1) of arsenotungstate components and ⁴F_3/2 → ⁴I_9/2 (11.43 × 10³ cm^-1) of Nd^III cations. Magnetic studies of 1 demonstrate its field-induced single-molecule magnet (SMM) behavior. Direct current magnetic susceptibility studies imply the weak ferromagnetic couplings present between the two neighboring Nd^III cations. In addition, the synergy between the coordination configuration of Nd^III cations and the intramolecular magnetic interaction was discussed.