The abrupt and hysteretic two-step spin crossover in a new triazole-based 2-D Hofmann-type complex shows a record breaking 120 K intermediate plateau (IP) region stabilized by negative cooperative interactions.

Polymers [{Zn ₂ (OAc) ₄ (4′-(4-ROC ₆ H ₄ )-4,2′:6′,4′′-tpy)} _n ] with dominant π-stacking interactions are favoured for small RO groups; with long chains, there is a switch to discrete molecules.

The origin of the metal-to-insulator transition (MIT) in $R{\mathrm{NiO}}_3$ perovskites with $R$ = trivalent $4f$ ion has challenged the condensed matter research community for almost three decades. A drawback for progress in this direction has been the lack of studies combining physical properties and accurate structural data covering the full nickelate phase diagram. Here we focus on a small region close to the itinerant limit $(R$ = Pr, $1.5\text{K}<T<300$ K), where we investigate the gap opening and the simultaneous emergence of charge order in ${\mathrm{PrNiO}}_3$. We combine electrical resistivity, magnetization, and heat capacity measurements with high-resolution neutron and synchrotron x-ray powder diffraction data that, in contrast to previous studies, we analyze in terms of symmetry-adapted distortion modes. Such analysis allow us to identify the contribution of the different modes to the global distortion in a broad temperature range. Moreover, it shows that the structural changes at the MIT, traditionally described in terms of the evolution of the interatomic distances and angles, appear as abrupt increases of $all$ nonzero mode amplitudes at $T_{\mathrm{MIT}}=T_N\sim 130$ K accompanied by the appearance of new modes below this temperature. A further interesting observation is the existence of a nearly perfect linear correlation between the amplitude of the breathing mode associated to the charge order and the staggered magnetization below the MIT. Our data also uncover a previously unnoticed anomaly at $T^{*}\sim 60$ K $\left(\sim 0.4\times T_{\mathrm{MIT}}\right)$, clearly visible in the electrical resistivity, lattice parameters and some mode amplitudes. Since phase coexistence is only observed in a small temperature region around $T_{\mathrm{MIT}}(\sim \pm 10$ K), these observations suggest the existence of a hidden symmetry in the insulating phase. We discuss some possible origins, among them the theoretically predicted existence of polar distortions induced by the noncentrosymmetric magnetic order [Perez-Mato et al., J. Phys.: Condens. Matter 28, 286001 (2016); Giovanetti et al., Phys. Rev. Lett. 103, 156401 (2009)].

Phosphonic acid-functionalized bpy ligands with 2-thienyl spacers are effective anchors in [Cu(L _anchor )(L _ancillary )] ⁺ dyes; DSC performance depends on the position of substitution of the PO(OH) ₂ group.

DSCs containing copper(i) bis(diimine) dyes with CF₃groups show photoconversion efficiencies of ≈30–34% relative to N719 set at 100%.