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SrMnO3 has a rich epitaxial strain-dependent ferroic phase diagram, in which a variety of magnetic orderings, even ferroelectricity, and thus multiferroicity, are accessible by gradually modifying the strain. Different relaxation processes, though, including the presence of strain-induced oxygen vacancies, can severely curtail the possibility of stabilizing these ferroic phases. Here, we report on a thorough investigation of the strain relaxation mechanisms in SrMnO3 films grown on several substrates imposing varying degrees of strain from slightly compressive (−0.39%) to largely tensile ≈+3.8%. First, we determine the strain dependency of the critical thickness (tc) below which pseudomorphic growth is obtained. Second, the mechanisms of stress relaxation are elucidated, revealing that misfit dislocations and stacking faults accommodate the strain above tc. Yet, even for films thicker than tc, the atomic monolayers below tc are proved to remain fully coherent. Therefore, multiferroicity may also emerge even in films that appear to be partially relaxed. Last, we demonstrate that fully coherent films with the same thickness present a lower oxygen content for increasing tensile mismatch with the substrate. This behavior proves the coupling between the formation of oxygen vacancies and epitaxial strain, in agreement with first-principles calculations, enabling the strain control of the Mn3+/Mn4+ ratio, which strongly affects the magnetic and electrical properties. However, the presence of oxygen vacancies/Mn3+ cations reduces the effective epitaxial strain in the SrMnO3 films and, thus, the accessibility to the strain-induced multiferroic phase., This work was financially supported by the Spanish Ministry of Science through project MAT2017-82970-C2-1-R and MAT2017-82970-C2-2-R and the Aragón Regional Government through projects E13_20R and E28_20R (Construyendo Europa desde Aragón). This project received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 823717—ESTEEM3.

Graphitic carbon nitride (g-C3N4) is a metal-free heterogeneous catalyst that has attracted attention because of its good chemical stability, cost-effectiveness, and environmental friendliness. In the work presented herein, F,O,S-codoped carbon nitride was synthesized by heating a mixture of melamine cyanurate and trifluoromethanesulfonic acid at 550 °C for 50 min. The obtained product was characterized by transmission electron microscopy, infrared spectroscopy, X-ray powder diffraction, CHNS elemental analysis, total combustion-ion chromatography, X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and UV-Vis spectroscopy. Results point to an F,O,S-codoped g-C3N4. The material was applied as a photocatalyst for the formation of benzoxazoles and benzimidazoles by condensation–aromatization of 2-aminophenol or 1,2-phenylenediamine with suitable aldehydes (viz. benzaldehyde, 4-chlorobenzaldehyde, 2-naphthaldehyde, 2-hydroxybenzaldehyde, and 2-methoxybenzaldehyde), obtaining yields of up to 90% in 15 min under visible light irradiation, with good selectivity and reusability. Thus, the reported findings suggest that this F,O,S-codoped g-C3N4 may hold promise as a metal-free photocatalyst for the rapid synthesis of 2-arylbenzoxazoles and 2-arylbenzimidazoles.

The remarkable advances in molecular logic reported in the last decade demonstrate the potential of luminescent molecules for logical operations, a paradigm‐changing concerning silicon‐based electronics. Trivalent lanthanide (Ln3+) ions, with their characteristic narrow line emissions, long‐lived excited states, and photostability under illumination, may improve the state‐of‐the‐art molecular logical devices. Here, the use of monolithic silicon‐based structures incorporating Ln3+ complexes for performing logical functions is reported. Elementary logic gates (AND, INH, and DEMUX), sequential logic (KEYPAD LOCK), and arithmetic operations (HALF ADDER and HALF SUBTRACTOR) exhibiting a switching ratio >60% are demonstrated for the first time using nonwet conditions. Additionally, this is the first report showing sequential logic and arithmetic operations combining molecular Ln3+ complexes and physical inputs. Contrary to chemical inputs, physical inputs may enable the future concatenation of distinct logical functions and reuse of the logical devices, a clear step forward toward input–output homogeneity that is precluding the integration of nowadays molecular logic devices., This work was developed within the scope of the project CICECO‐Aveiro Institute of Materials (UIDB/50011/2020 and UIDP/50011/2020), financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. This work was financially supported by the project NanoHeatControl (POCI‐01‐0145‐FEDER‐031469), funded by FEDER, through POCI, and by Portuguese funds (OE), through FCT/MCTES, and by the Spanish Ministry of Science Innovation and Universities (Grant No. PGC2018_095795_B_I00) and the Diputación General de Aragón (Grant No. E11/17R). C.D.S.B. and M.A.H.‐R. thank SusPhotoSolutions (CENTRO‐01‐0145‐FEDER‐000005) for grants.

International audience; The reactivity of two classes of ruthenium nanoparticles (Ru NPs) of small size, either sterically stabilized by a polymer (polyvinylpyrrolidone, PVP) or electronically stabilized by a ligand (bisdiphenylphosphinobutane, dppb) was tested towards standard reactions, namely CO oxidation, CO2 reduction and styrene hydrogenation. The aim of the work was to identify the sites of reactivity on the nanoparticles and to study how the presence of ancillary ligands can influence the course of these catalytic reactions by using NMR and IR spectroscopies. It was found that CO oxidation proceeds at room temperature (RT) on Ru NPs but that the system deactivates rapidly in the absence of ligands because of the formation of RuO2. In the presence of ligands, the reaction involves exclusively the bridging CO groups and no bulk oxidation is observed at RT under catalytic conditions. The reverse reaction, CO2 reduction, is achieved at 120 °C in the presence of H2 and leads to CO, which coordinates exclusively in a bridging mode, hence evidencing the competition between hydrides and CO for coordination on Ru NPs. The effect of ligands localized on the surface is also evidenced in catalytic reactions. Thus, styrene is slowly hydrogenated at RT by the two systems Ru/PVP and Ru/dppb, first into ethylbenzene and then into ethylcyclohexane. Selectively poisoning the nanoparticles with bridging CO groups leads to catalysts that are only able to reduce the vinyl group of styrene whereas a full poisoning with both terminal and bridging CO groups leads to inactive catalysts. These results are interpreted in terms of location of the ligands on the particles surface, and evidence site selectivity for both CO oxidation and arene hydrogenation.

The thermal gradients generated at submicrometer scale by the millions of transistors contained in integrated circuits are becoming the key limiting factor for device integration in micro- and nanoelectronics. Noncontact thermometric techniques with high-spatial resolution are, thus, essential for noninvasive off-chip characterization and heat management on Si surfaces. Here, the first ratiometric luminescent molecular thermometer implemented in a self-assembled polymer monolayer functionalized Si surface is reported. The functionalization of Si surfaces with luminescent thermometers constitutes a proof-of-concept that foretells a wide range of applications in Si-based micro- and nanostructures. The thermometric functionalization of the Si surface with Tb3+ and Eu3+ complexes leads to a thermal sensitivity up to 1.43% K−1, a cycle–recycle reliability of 98.6%, and a temperature uncertainty of less than 0.3 K. The functionalized surface presents reversible bistability that can be used as an optically active molecular demultiplexer., Financial support from the Spanish Ministry of Science and Innovation research grants BFU2009-12763/BFI, MAT2011-259911, TEC2011-29140, and TEC2014-51940, and Project Consolider-Ingenio in Molecular Nanoscience CSD2007-00010 are gratefully acknowledged. Moreover, the work was partially developed in the scope of the project CICECO − Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by Portuguese funds through the FCT/MEC and when applicable cofinanced by FEDER under the PT2020 Partnership Agreement. C.D.S.B. and N.J.O.S. thank the Portuguese Fundação para a Ciência e Tecnologia (FCT) for their grants (SFRH/BPD/89003/2012 and IF/01653/2013, respectively).

Reduction of [([Formula: see text])2][As6]2 with triphenylantimony and tetrabutylammonium chloride produced the diradical 5,5'-bis(1,3,2,4-dithiadiazolyl) [[Formula: see text]-[Formula: see text]] in high yield as a black solid with widely ranging magnetic susceptibilities (e.g., 0.6 to 2.6 μB), which on oxidation with AsF5 regenerated [([Formula: see text])2][AsF6]2. The identity of [[Formula: see text]-[Formula: see text]] was established from EPR, vibrational, and mass spectra. Ab initio molecular orbital [MPW1PW91/6-311G(2df)] calculations show the lowest energy structure to consist of two coplanar rings separated by a C—C single bond (1.444 Å), reflected in the comparison of the vibrational spectra of the diradical with that of [([Formula: see text])2][AsF6]2 and the calculated spectra. Confidence in the calculated [MPW1PW91/6-311G(2df)] structure of the diradical is supported by the excellent agreement between the calculated and X-ray single crystal structure geometries of [[Formula: see text]]2 and [([Formula: see text])2]2+ in [([Formula: see text])2][AsF6]2. The molecular orbitals indicate the diradical is essentially disjoint, confirmed by a very small (0.07 kJ mol–1) GVB-PP(TC-SCF)/6-311G* calculated singlet–triplet energy gap. Accordingly, the EPR spectrum of the diradical (in tetrahydrofuran, 293 K) shows a simple 3-line pattern (g = 2.0043, a(14N) = 1.11 mT) with no observable exchange coupling between the two radical centers. Mechanical grinding of the diradical results in a large increase in paramagnetism (e.g., from 1.03 to 2.55 μB) that is unprecedented in main group chemistry. The X-ray diffraction data of the ground and unground powder are consistent with a second order phase change on grinding. Attempts to obtain crystals of the diradical by sublimation led instead to numerous decomposition and rearrangement products, including 4-cyano-1,2,3,5-dithiadiazolyl [NC-[Formula: see text]], monoclinic space group C2/c, a = 9.46(2) Å, b = 7.625(5) Å, c = 13.17(2) Å, β = 107.94(4)°, Z = 8. The structure consists of axially symmetric, co-facial, cis dimers linked to form strands through two sets of C[Formula: see text]Nδ–···Sδ+ contacts. More efficient and larger scale preparations of [SNS][AsF6] and [([Formula: see text])2][AsF6]2 are reported. Key words: 5,5'-bis(1,3,2,4-dithiadiazolyl), diradical, paramagnetism, mechanical grinding, second order phase change, 4-cyano-1,2,3,5-dithiadiazolyl.

Heat capacities of the organic free radical magnet 2-tert-butylaminoxylbenzimidazole (BABI) have been measured in the 0.2−300 K range by adiabatic calorimetry for investigation of its magnetic properties from a thermodynamic viewpoint. An antiferromagnetic phase transition was observed at TN = 1.7 K. A heat capacity hump arising from short-range spin ordering characteristic of low-dimensional magnets was found around 2 K. The magnetic enthalpy and entropy were determined to be 17.4 J mol-1 and 5.34 J K-1 mol-1, respectively. The magnitude of the magnetic entropy is in good agreement with the theoretical value for the magnetic ordering of spin quantum number S = 1/2 systems, R ln 2 = 5.76 J K-1 mol-1, where R is the gas constant. The heat capacity hump above TN is well reproduced by the S = 1/2 two-dimensional antiferromagnetic bilayer Heisenberg model with the intralayer interaction J1/kB = −1.2 K and the interlayer interaction J2/kB = −1.9 K, where kB is the Boltzmann constant. The bilayer model gives a ...

Various examples are described of a multi-strategy approach to improvement of multispin exchange design. For example, H-bonded benzimidazole 4-t-butylnitroxide shows apparent simple planar 2D-type interaction, with a Weiss constant of Θ = −4.24 K and an intraplane exchange interaction of J = −1.60 K.

Cleverly designed molecular building blocks provide chemists with the tools of a powerful molecular-scale construction set. They enable them to engineer materials that possess a predictable order and useful solid-state properties. Hence, it is in the realm of supramolecular chemistry to follow a strategy for synthesizing materials which combine a selected set of properties, for instance from the areas of magnetism, photophysics and electronics. As a possible approach, host/guest solids which are based on extended anionic, homo- and bi-metallic oxalato-bridged transition-metal compounds with two- and three-dimensional connectivities are investigated. In particular, we report herein in detail about their structural properties and their multifunctional characteristics in the area of molecular magnetism and photophysics.

The crystal structures of a series of dithiadiazolyl free radicals, p-XC6F4CNSSN (X˭F,Cl,Br and CN) are described in terms of dipolar interactions which induce chain-like motifs in the solid state. When X˭CN two morphologies are observed; the β-phase is polar and undergoes a phase transition to a weakly ferromagnetic state at 36K, an unprecedented temperature for an organic radical. The polar structure which gives rise to weak ferromagnetism in β-p-NCC6F4CNSSN, also provides a number of other potential solid state properties which may interact independently or cooperatively with the magnetic behaviour.

Highly oriented thin films of the organic radical p- NC.C 6 F 4 .CNSSN have been prepared by thermal evaporation in high vacuum on glass and on highly oriented pyrolytic graphite (HOPG) substrates. The films are polycrystalline and crystallize in one of the known polymorphs, in the triclinic α -phase. The films exhibit a high degree of orientation with their (112) planes parallel to the surface of the substrates. No in-plane texture is observed.

The title nitroxide is stable at room temperature for months. ESR spectroscopy shows moderate spin delocalization from the nitroxide unit onto the benzimidazole unit. The radical crystallizes in th...

Co-sublimation of the dithiadiazolyl radical, p-NCC 6 H 4 CNSSN 2 with the inclusion-forming host compound perhydrotriphenylene (PHTP) leads to trichroic crystals of the host-guest complex [PHTP-2]. Molecules of 2 are linked through a CN‥S interaction (ca. 3.03 A) to form polar chains within the channels of the PHTP host lattice. The host-guest ratio is approximately 5:1. Pyroelectric and non-linear optic responses indicate that crystals of [PHTP-2] are macroscopically polar. A combination of variable temperature solid state EPR spectroscopy and magnetic susceptibility measurements are used to probe the electronic properties of [PHTP-2]; whilst [PHTP-2] is paramagnetic, no exchange coupling between neighbouring molecules of 2 within the channels could be established. The implications of these results on the magnetic exchange pathway of the weak ferromagnet, β-p-NCC 6 F 4 CNSSN β-1, are discussed.

The radical p-NCC6F4CNSSN, 1, can be obtained in two different phases depending upon sublimation conditions. The α-phase, lα, crystallises in space group P 1, and the molecules are related through an inversion centre. The β- phase, lβ crystallises in the orthorhombic space group Fdd2 and the molecules are not related by an inversion centre. The latter shows a sharp rise in the magnetic susceptibility at 36K which is accompanied by an out-of-phase component in the a.c. susceptibility. Heat capacity measurements show a distinct peak at 35.5K indicative of the long range ordering of the magnetic moments. The magnetic ordering of the compound is also confirmed by neutron diffraction experiments. Magnetisation isotherms indicate the presence of a small residual moment that saturates below 100 Oe. Extrapolation of the residual moment at T= 0K gives a value for the spontaneous magnetisation of 1.5×l0−3 μB/molecule. The behaviour is interpreted in terms of weak ferromagnetism.

Two dithiadiazolyl radicals of formula [F 2 C 6 H 3 CNSSN] ˙ were prepared and characterised by X-ray crystallography; in the solid state the 2′,3′-difluoro isomer forms discrete twisted dimers through a spin-paired singly occupied–singly occupied molecular orbital interaction with an intra-dimer S · · · S distance of 3.020(4) A, whereas the 2′,5′-isomer is composed of uniform stacks with unexpectedly long intra-stack S · · · S contacts [3.544(3) A].

The application of sulfur-nitrogen free-radicals as molecular ‘bricks’ for the construction of novel magnetic materials is described and exemplified by the dithiadiazolyl radical, which becomes weakly ferromagnetic at 36K.

Cleverly designed molecular building blocks provide chemists with the tools of a powerful molecular-scale construction set. They enable them to engineer materials that have a predictable order and ...

Various examples are described of a multi-strategy approach to improvement of multispin exchange design. For example, H-bonded benzimidazole 4-t-butylnitroxide shows apparent simple planar 2D-type interaction, with a Weiss constant of Θ = −4.24 K and an intraplane exchange interaction of J = −1.60 K.

The mixed-metal compounds [P(Ph) 4 ][M II Cr(C 2 O 4 ) 3 ] (Ph = Phenyl; M = Mn, Fe) have been studied by calorimetric and magnetic AC and DC techniques. The Mn-derivative presents low dimensional magnetic character and shows evidence of the onset of a 3D-magnetic ordering. However, experimental results in the Fe-derivative point to a spin-glass-like behavior. The differences observed in the magnetic behavior of both compounds are assigned to the effect of random anisotropy due to the presence of structural disorder.

Cleverly designed molecular building blocks provide chemists with the tools of a powerful molecular-scale construction set. They enable them to engineer materials having a predictable order and useful solid-state properties. Hence, it is in the realm of supramolecular chemistry to follow a strategy for synthesizing materials which combine a selected set of properties, for instance from the areas of magnetism, photophysics and electronics. As a successful approach, host/guest solids which are based on extended anionic, homo- and bimetallic oxalato-bridged transition-metal compounds with two-and three-dimensional connectivities have been investigated. In this report, a brief review is given on the structural aspects of this class of compounds followed by a presentation of a thermal and magnetic study for two distinct, heterometallic oxalato-bridged layer compounds.

Magnetization, heat capacity, and neutron diffraction experiments on the \ensuremath{\beta}-phase of the dithiadiazolyl radical, p-NC.${\mathrm{C}}_{6}$${\mathrm{F}}_{4}$.CNSSN., provide conclusive evidence that this system exhibits noncollinear antiferromagnetism at 35.5 K, an unprecedented temperature for an organic radical. On the basis of magnetization and powder neutron diffraction results, coupled with theoretical calculations of the spin distribution within the molecule, a magnetic structure for this compound is proposed in which the interactions propagate through $\mathrm{S}\dots{}\mathrm{N}$ contacts.