Sublimable Single Ion Magnets Based on Lanthanoid Quinolinate Complexes: The Role of Intermolecular Interactions on Their Thermal Stability.

We report the design, preparation, and characterization of two families of thermally robust coordination complexes based on lanthanoid quinolinate compounds: [Ln(5,7-Br2q)4]- and [Ln(5,7-ClIq)4]-, where q = 8-hydroquinolinate anion and Ln = DyIII, TbIII, ErIII, and HoIII. The sodium salt of [Dy(5,7-Br2q)4]- decomposes upon sublimation, whereas the sodium salt of [Dy(5,7-ClIq)4]-, which displays subtly different crystalline interactions, is sublimable under gentle conditions. The resulting film presents low roughness with high coverage, and the molecular integrity of the coordination complex is verified through AFM, MALDI-TOF, FT-IR, and microanalysis. Crucially, the single-molecule magnet behavior exhibited by [Dy(5,7-ClIq)4]- in bulk remains detectable by ac magnetometry in the sublimated film.

The combination of a polymer-carbon composite electrode with a high-absorptivity ruthenium dye achieves an efficient dye-sensitized solar cell based on a thiolate-disulfide redox couple.

To overcome the intrinsic shortcomings of the traditional iodide-triiodide redox couple and pursue a further performance improvement, intense efforts have been made to exploit alternative redox shuttles in dye-sensitized solar cells (DSCs). Herein, we report an energetic and kinetic view of DSCs when the iodine electrolyte is substituted with its thiolate counterpart and identify that a conventional platinum counter electrode presents low catalytic activity for the thiolate electrolyte, featuring a high charge transfer resistance found at the platinized fluorine-doped tin oxide (FTO). We employ conductive carbon black with several polymers to fabricate highly active composite catalysts for thiolate regeneration. The use of a highly active conductive carbon black and polymerized 3,4-ethylenedioxythiophene composition as a counter electrode combined with a high-absorptivity ruthenium dye C106 sensitized titania film has generated a DSC with an organic thiolated electrolyte, exhibiting an overall power conversion efficiency of 7.6% under AM1.5G full sunlight.

Giant Enhancement in the Supercapacitance of NiFe-Graphene Nanocomposites Induced by a Magnetic Field.

The rapid rise in energy demand in the past years has prompted a search for low-cost alternatives for energy storage, supercapacitors being one of the most important devices. It is shown that a dramatic enhancement (≈1100%, from 155 to 1850 F g-1 ) of the specific capacitance of a hybrid stimuli-responsive FeNi3 -graphene electrode material can be achieved when the charge/discharge cycling is performed in the presence of an applied magnetic field of 4000 G. This result is related to an unprecedented magnetic-field-induced metal segregation of the FeNi3 nanoparticles during the cycling, which results in the appearance of small Ni clusters (<5 nm) and, consequently, in an increase in pseudocapacitive sites. The results open the door to a systematic improvement of the capacitance values of hybrid supercapacitors, while moving the research in this area towards the development of magnetically addressable energy-storage devices.

Sublimable chloroquinolinate lanthanoid single-ion magnets deposited on ferromagnetic electrodes.

A new family of chloroquinolinate lanthanoid complexes of the formula A+[Ln(5,7Cl2q)4]-, with Ln = Y3+, Tb3+ and Dy3+ and A+ = Na+, NEt4+ and K0.5(NEt4)0.5+, is studied, both in bulk and as thin films. Several members of the family are found to present single-molecule magnetic behavior in bulk. Interestingly, the sodium salts can be sublimed under high vacuum conditions retaining their molecular structures and magnetic properties. These thermally stable compounds have been deposited on different substrates (Al2O3, Au and NiFe). The magnetic properties of these molecular films show the appearance of cusps in the zero-field cooled curves when they are deposited on permalloy (NiFe). This indicates a magnetic blocking caused by the interaction between the single-ion magnet and the ferromagnet. X-ray absorption spectroscopy confirms the formation of hybrid states at the molecule/metal interface.