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Highly conducting, mixed-valence, multi-component nickel bis(diselenolene) salts were obtained by electrocrystallization of the monoanionic species [Ni(Me-thiazds)2]-1 (Me-thiazds: N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate), with 1:2 and 1:3 stoichiometries depending of the counter ion used (Et4N+ and nBu4N+ vs Ph4P+, respectively). This behavior strongly differs from that of the corresponding monoanionic dithiolene complexes whose oxidation afforded the single component neutral species. This provides additional rare examples of mixed-valence conducting salts of nickel diselenolene complexes, only known in two examples with the dsit (1,3-dithiole-2-thione-4,5-diselenolate) and dsise (1,3-dithiole-2-selone-4,5-diselenolate) ligands. The mixed-valence salts form highly dimerized or trimerized bi- and trimetallic units, rarely seen with such nickel complexes. Transport measurements under a high pressure (up to 10 GPa) and band structure calculations confirm the semiconducting character of [Ph4P][Ni(Me-thiazds)2]3 and the quasi metallic character of [Et4N][Ni(Me-thiazds)2]2 and [NBu4]x[Ni(Me-thiazds)2]2 salts (0 < x < 1)., This work was supported in part by Université de Rennes 1 (Ph.D. grant to H.H.) and by the JSPS KAKENHI (grant JP16H06346). The stay of H.H. to RIKEN was supported in part by the RIKEN International Program Associate and by Rennes Métropole. We thank Takaaki Minamidate (RIKEN) and Thierry Guizouarn (Rennes) for the magnetic susceptibility (SQUID) measurements. Work in Spain was supported by MINECO through Grants PGC2018-096955-B-C44 and PID2021-128217NB-I00, Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). E.C. acknowledges the support of the Spanish MINECO through the Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction and P.A. acknowledges the support from the Maria de Maeztu Units of Excellence Program (MDM-2017-0767). Their support is gratefully acknowledged., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Harnessing a bis(selenomethyl)tetrathiafulvalene (TTF) derivative as a donor, conducting charge transfer (CT) salts are realized thanks to original packing structures supported by chalcogen bonding (ChB) interactions. Specifically, reaction of EDT-TTF(SeMe)2 (EDT = ethylenedithio) with an acceptor, 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane (F2TCNQ), afforded two polymorphs of 1 : 1 CT salts, α- and β-[EDT-TTF(SeMe)2](F2TCNQ). The donor and the acceptor molecules in both polymorphs organize into segregated and uniform stacks. Based on the structure, the α-salt shows a quasi-complete CT while the β-salt shows a partial CT with ρ ∼±0.8. The oxidation of TTF activates the σ-hole on Se atoms to be engaged in highly linear ChB interactions with the N atoms on F2TCNQ. The formation of directional ChB interactions resulted in original packing structures of the donor and the acceptor stacks that are distinct between α- and β-salts. In particular, the ChB motif observed in the β-salt allows F2TCNQ molecules within the stack to be closer than those in the α-salt. Consequently, the α-salt is a semi-conductor, while the β-salt shows metallic behaviour with a two-step metal-to-insulator (MI) transition. Moreover, the observed MI transition temperature in the β-salt (180 K) is substantially higher than that in other known CT salts, likely owing to the 3D coupling of the modulation in different chains brought about by the -SeMe substituents., Work in France was supported by the French National Research Agency Grant ANR 17-ERC3-0003 and a PhD grant (to M. Beau) from Région Bretagne. We thank the CDIFX in Rennes for the use of the X-ray diffractometer. Work in Spain was supported by MICIU through Grants PGC2018-096955-B-C44 and PID2021-128217NB-I00, Generalitat de Catalunya (2021SGR01519 and 2021SGR00286). E. C. acknowledges the support of the Spanish MICIU through the Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction and P. A. acknowledges the support from the Maria de Maeztu Units of Excellence Program (CEX2021-001202-M)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Novel coordination polymers embedding electroactive moieties present a high interest in the development of porous conducting materials. While tetrathiafulvalene (TTF) based metal-organic frameworks were reported to yield through-space conducting frameworks, the use of S-enriched scaffolds remains elusive in this field. Herein is reported the employment of bis(vinylenedithio)-tetrathiafulvalene (BVDT-TTF) functionalized with pyridine coordinating moieties in coordination polymers. Its combination with various transition metals yielded four isostructural networks, whose conductivity increased upon chemical oxidation with iodine. The oxidation was confirmed in a single-crystal to single-crystal X-ray diffraction experiment for the Cd(II) coordination polymer. Raman spectroscopy measurements and DFT calculations confirmed the oxidation state of the bulk materials, and band structure calculations assessed the ground state as an electronically localized antiferromagnetic state, while the conduction occurs in a 2D manner. These results are shedding light to comprehend how to improve through-space conductivity thanks to sulfur enriched ligands., This work was supported in France by the CNRS and the University of Angers (PhD funding to F.S.). N.A. and I.O. thank the Narodowa Agencja Wymiany Akademickiej – NAWA (Poland, BPN/BFR/2021/1/00001/U/00001) and the French Ministry of Foreign Affairs and the French Ministry of Education and Research (France, PHC Project 48119PG) for financial support through the bilateral Polonium project. The work in Poland was supported within the Statutory Activities of the Institute of Molecular Physics Polish Academy of Sciences and partially supported at Poznan University of Technology by the Research Project of the Polish Ministry of Education and Science 0511/SBAD/2251. Work in Spain was supported by MICIU through Grants PGC2018-096955-B-C44 and PGC2018-093863-B-C22, and Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). E.C. acknowledges support of the Spanish MICIU through the Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction and P. A. from the Maria de Maeztu Units of Excellence Program (MDM-2017-0767)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Magnetic frustration results from competing magnetic interactions and leads to unusual ground states, ranging from non-collinear magnetic orders to spin liquids (SLs), opening the path to new physics and emerging properties. We report the engineered magnetic interaction design and synthesis of the new ternary nitride MnTa2N4 with a normal spinel structure, where the magnetic cations Mn2+ occupy exclusively the tetrahedral sites forming a diamond lattice. Although the magnetic interactions are strongly antiferromagnetic (θCW ≈ -140 K), a long-range magnetic order is not established, but a smooth magnetic anomaly is observed at T∗ ≈ 5.1 K, fingerprinting a large magnetic frustration. A short-range helicoidal magnetic order emerges at low temperatures. The ordered moment is ≈70% of the expected magnetic moment of Mn2+ ions and a large part (≈28%) of the spin entropy remains at 400 mK, signaling the coexistence of a helicoidal order with spin-glass-like or SL textures. First-principles calculations unveil an unexpected large direct Mn-Mn exchange interaction that balances the superexchange and accounts for the magnetic frustration. These findings open new avenues toward the design of quantum materials., This work was supported by the Ministerio de Ciencia e Innovación, Spain (PID2020-113805GB-I00, PID2020-118479RB-I00 (AEI/FEDER, EU), PGC2018-096955-B-C44 ,PGC2018-093863-B-C22, CEX2019-000917-S and MDM-2017-0767) and from Generalitat de Catalunya (2017SGR1377, 2017SGR581, 2017SGR1506, and 2017SGR1289). We thank Alba and ILL for beam time provision (experiments 2019023454 and 5-31-2713, respectively), Dr. François Fauth for assistance in data collection at Alba, and Dr. Bernat Bozzo (ICMAB-CSIC) for performing magnetic measurements. The authors acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

The multiferroic properties of the BiFeO3 (BFO) compound have received great attention for decades. To date, there are many detailed experimental and theoretical studies on the coexistence of ferroelectric (FE) and antiferromagnetic (AFM) orderings in the BFO which can show up a weak-ferromagnetism (w-FM) by canting of the ferromagnetic (FM) sublattice; however, there are only a few reports in the literature on BFO with FM ordering at the interfaces in heterostructures and, apparently, none on bulk FM BFO. Recently, a novel FM state coexisting with FE ordering at room temperature has been reported in (0 1 2)-oriented and strained BFO thin films [Ramirez-Camacho et al. Acta Materialia 128, 451–454 (2017)]. Based on such observed FM in BFO, the aim of our work is the theoretical study on the possibility of existence and stability of a macroscopic FM order coexisting with the FE arrangement in bulk BFO to explain the causes that lead to the observed FM-FE ordering. We outline the conditions that must be fulfilled by the crystalline structure, chemical bonding, and electronic structure employing the density functional theory (DFT) + Hubbard potential (U) formalism and using a combination of different representations as density of states, band structure, electron density, electron localization function, and molecular orbital. Our work demonstrates that the stable FM ordering is consequence of a small increase of the rhombohedral distortions and is strongly associated to higher degree of covalence of the spin-up eg orbitals in the Fe O bonds, and it is established by indirect exchange interactions such as superexchange and/or double-exchange interactions which are mediated by the oxygen ions located between the Fe ions. In particular, the electronic structure features of the possible FM order in the BFO compound suggest potential applications as voltage-controlled magnetic semiconductor for spin inverters in Spintronics.

Nickel(II) bis(dithiolene) complexes can provide crystalline conducting materials either in their monoanionic or neutral forms. Here we show that the use of chiral dithiolene ligands with one or two stereogenic centres, together with variation of the counter-ion in the anionic complexes, represents a powerful strategy to modulate the conducting properties of such molecular materials. The chiral ligands 5-methyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (me-dddt) and 5,6-dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) have been generated from the thione precursors 1 and 2 which have been structurally and chiroptically characterized. Anionic Ni(II) complexes of these two ligands with tetrabutyl-ammonium (TBA) and tetramethyl-ammonium (TMA) have been prepared and structurally characterized, suggesting that it is the nature of the counter-ion which mostly influences the solid state organization of the complexes. Both TBA and TMA radical anion salts are Mott insulators with antiferromagnetic ground state, as suggested by spin polarized DFT band structure calculations. However, the TMA salts are one order of magnitude more conducting than the TBA counterparts. The neutral materials [Ni(me-dddt)2] and [Ni(dm-dddt)2] are direct band gap semiconductors, as determined by DFT and extended Hückel band structure calculations, with their conductivity drastically increased up to 0.05–3.3 S cm−1 under the highest applied pressures of 10–11 GPa. At equivalent applied pressures the dm-dddt materials are more conducting than the me-dddt ones, in agreement with the lower calculated activation energy and larger bands dispersion for the former. This trend follows the structural change when going from one to two methyl substituents, since the packing and intermolecular interactions are completely different between [Ni(dm-dddt)2] and [Ni(me-dddt)2], the packing of the latter being related to the one of the achiral parent [Ni(dddt)2]. Subtle differences of conductivity are also observed within both series of neutral complexes between the enantiopure and racemic forms. This represents the first series of chiral nickel bis(dithiolene) complexes which shows modulation of the conducting properties with the number of stereogenic centres, the conductivity, measured on single crystals, strongly increasing upon applying hydrostatic pressure., This work was supported in France by the National Agency for Research (ANR, Project 15-CE29-0006-01 ChiraMolCo), the CNRS and the University of Angers. Laurent Veyre (CPE Lyon, France) is gratefully acknowledged for technical help with the synthesis of precursor (rac)-2. Work in Spain was supported by MICIU (Spain) through Grants PGC2018-096955-B-C44 and PGC2018-093863-B-C22, and by Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). E. C. acknowledges support of the Spanish MICIU through the Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction and P. A. from the Maria de Maeztu Units of Excellence Program (MDM-2017-0767). The work in Japan was supported by JSPS KAKENHI (Grants No. 16H06346).

This article describes the enhanced sensitivity to a viscous medium by a molecular rotor based fluorophore (RBF), TPSI I. The TPSI I molecule is designed in such a way that it consists of a rotor and a fluorophore with a p-rich bridge between them. TPSI I is a light-responsive material in solution as well as in the solid state. The structural design of the molecule allows flexible rotation and photo-induced cis-trans isomerization both in the solid state as well as in solution. These combined attributes of TPSI I are responsible for the ultrasensitive viscosity response of the new material, which was verified through the Fo ̈rster-Hoffmann equation. According to this equation, the derived 'x' value is 1.02 (x is related to the sensitivity) which is the highest among the contemporary reports for RBFs. The facts were evidenced both by experimental as well as theoretical data. The ultrasensitivity towards viscosity was further analyzed in in vitro studies by detecting the subtle changes in the alteration of intracellular viscosity in normal and cancerous cells. An alteration of intracellular viscosity in cells treated with viscosity modula- tors was also confirmed using a previously well-established viscosity measurement technique, dynamic measurement through the piezoelectric patch. Our research offers a detailed mechanism to improve viscosity sensors and an efficient probe for detecting minute changes in intracellular viscosity.

Layered group V transition-metal trichalcogenides are paradigmatic low-dimensional materials providing an ever increasing series of unusual properties. They are all based on the same basic building units, one-dimensional MX3 (M = Nb, Ta; X = S, Se) trigonal-prismatic chains that condense into layers, but their electronic structures exhibit significant differences leading to a broad spectrum of transport properties, ranging from metals with one, two, or three charge density wave instabilities to semimetals with potential topological properties or semiconductors. The different physical and chemical properties are shown to be related with subtle structural differences within the layers that result in half-, third-, or quarter-filled quasi-one-dimensional Nb dz2-type bands, providing a clear-cut illustration of the intimate link between structural and electronic features within a family of solids. An interesting yet not sufficiently explored feature of these solids is the polymorphism. Based on both experimental and new theoretical results, we examine this aspect for NbS3 and show that at least seven different polymorphs with a stability compatible with the presently known phases of this compound are possible. We discuss a simple rationale for the physical properties of the presently known polymorphs as well as predictions for those that have still not been characterized or prepared. It is argued that some of the presently unknown polymorphs may have been prepared in an uncontrolled way as mixtures of different phases which could not be structurally characterized. The rich landscape of structures and properties found for this van der Waals material is suggested to represent an ideal platform for the preparation of flakes with fine-tuned properties for applications in new electronic and optoelectronic devices., This work was supported by the Spanish MICIU through grants PGC2018-096955-B-C44 and PGC2018-093863-B-C22, the Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction, the Maria de Maeztu Units of Excellence Program (MDM-2017-0767), and Generalitat de Catalunya (grants nos. 2017SGR1506 and 2017SGR1289). S.C. was supported by FONDECYT, Chile (project 11171063).

Two new d10 metal supramolecular metal&ndash, organic frameworks (SMOFs) with general formula [ML2(H2O)2]n (M = Zn, Cd) have been synthetized using the sodium salt of the anionic 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand (Na+L&minus, ). Both SMOFs have been structurally characterized by single-crystal X-ray diffraction analysis and IR spectroscopy. The compounds are isostructural and form supramolecular aggregates via hydrogen bonds with the presence of less common dihydrogen bonds. Interestingly, they show ionic conductivity and porosity. The luminescent properties have been also studied by means of the excitation and emission spectra. Periodic DFT and molecular TD-DFT calculations have been used to unravel the emergence of luminescence in the otherwise non-emitting 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand once incorporated in the SMOFs. Our results also illustrate the importance of considering the dielectric environment in the crystal when performing excited state calculations for isolated fragments to capture the correct electronic character of the low-lying states, a practice which is not commonly adopted in the community.

Two new d10 metal supramolecular metal–organic frameworks (SMOFs) with general formula [ML2(H2O)2]n (M = Zn, Cd) have been synthetized using the sodium salt of the anionic 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand (Na+L−). Both SMOFs have been structurally characterized by single-crystal X-ray diffraction analysis and IR spectroscopy. The compounds are isostructural and form supramolecular aggregates via hydrogen bonds with the presence of less common dihydrogen bonds. Interestingly, they show ionic conductivity and porosity. The luminescent properties have been also studied by means of the excitation and emission spectra. Periodic DFT and molecular TD-DFT calculations have been used to unravel the emergence of luminescence in the otherwise non-emitting 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand once incorporated in the SMOFs. Our results also illustrate the importance of considering the dielectric environment in the crystal when performing excited state calculations for isolated fragments to capture the correct electronic character of the low-lying states, a practice which is not commonly adopted in the community.

Non-centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON

Inorganic phosphors based on monoclinic Y2WO6 doped with Sm3+ ions were prepared via conventional solid-state reactions at high temperature. A total of six samples were obtained with different Sm3+ concentrations (0–9%). The purity of the as-prepared phases was checked by powder X-ray diffraction (PXRD). The excitation, emission, and time-resolved emission spectra were examined in detail. The experimental decay curves were fitted to the Inokuti–Hirayama model, showing that the Sm3+ ions form clusters at all compositions. Periodic hybrid density functional theory calculations were also carried out on the undoped material and on 144-atom supercells of stoichiometry Y1.9375Sm0.0625WO6 and Y1.875Sm0.125WO6. The different coordination environments at the Y1, Y2 and Y3 sites are analysed in detail. The calculated structure and band gap of Y2WO6 are in good agreement with experiment with one potentially important discrepancy in a Y3-O bond length. The thermodynamically favoured substitution sites for Sm, Y2 and Y3, in the supercell are not those observed under the preparation conditions used here, since the experimental Rietveld analysis suggests occupation of Y1 at all concentrations. Analogous calculations for the Eu-doped system highlight marked differences between Eu and Sm despite their similar ionic sizes. The calculateddensities of states show the position of the 4f levels in the band gap depend on thesites occupied by the dopants and thus we expect marked differences in the luminescencespectra, opening up possibilities for tuning device performance.

We report an investigation of the combined structural and electronic properties of the bronze ${\mathrm{Na}}_{1.5}{({\mathrm{PO}}_{2})}_{4}{({\mathrm{WO}}_{3})}_{20}$. Its low-dimensional structure and possible large reconstruction of the Fermi surface due to charge density wave instability make this bulk material a natural superlattice with a reduced number of carriers and Fermi energy. Signatures of multilayered two-dimensional (2D) electron weak localization are consequently reported, with an enhanced influence of quantum oscillations. A crossover between these two antagonistic entities, previously observed only in genuine low-dimensional materials and devices, is shown to occur in a bulk crystal due to its hidden 2D nature.

The relationship between chirality and superconductivity is an intriguing question. The two enantiomeric crystalline radical cation salts κ-[(S,S)-DM-BEDT-TTF]

Methyl- and dimethyl-ethylenedithio-tetrathiafulvalene ortho-diamide donors Me-EDT-TTF(CONH2)2 (1a) and DM-EDT-TTF(CONH2)2 (1b) have been prepared by the direct reaction of the corresponding diester precursors with aqueous ammonia solutions. The neutral (rac)-1a, (R)-1a, and (S,S)-1b donors have been characterized by single crystal X-ray diffraction. In the three compounds, which crystallized in the non-centrosymmetric monoclinic space group P21, the amide groups are disordered, yet they form the classical intramolecular hydrogen bond for such an ortho-diamide motif. Electrocrystallization experiments afforded the mixed valence radical cation salts [(S,S)-1b]2XO4 and [(R,R)-1b]2XO4 (X = Cl, Re) containing four independent donors in the asymmetric unit, with the positive charge localized essentially on two donors, while the two others are neutral. The topology of the organic layer is of β′-type. Single crystal resistivity measurements show semiconducting behavior for [(S,S)-1b]2ClO4 and [(R,R)-1b]2ReO4, with a room temperature conductivity of 5 × 10–5 S cm–1 and activation energies Ea ≈ 3000 K. Tight-binding band structure calculations of extended Hückel type in combination with density functional theory calculations are in agreement with the semiconducting behavior and suggest a localized Mott type semiconductor rather than a band gap semiconductor., This work was supported in France by the National Agency for Research (ANR, Project 15-CE29-0006-01 ChiraMolCo), the CNRS and the University of Angers. Work in Spain was supported by MICIU (PGC2018-096955-B-C44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria deMaeztu (MDM-2017-0767) Programs and the Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). Ingrid Freuze and Sonia Jerjir (University of Angers) are gratefully acknowledged for the MS characterization.

Here, the first accurate study is presented of the room-temperature and 100 K structures of one of the first organic spin liquids, -(BEDT-TTF)2Ag2(CN)3. It is shown that the monoclinic structure determined previously is only the average one. It is shown that the exact structure presents triclinic symmetry with two non-equivalent dimers in the unit cell. But surprisingly this does not lead to a sizeable charge disproportionation between dimers. The difference from the analogue compound -(BEDT-TTF)2Cu2(CN)3 which also presents a spin liquid phase is discussed in detail. The data provided here show the importance of the anionic layer and in particular the transition metal position in the process of symmetry breaking. The possible impact of the symmetry breaking, albeit weak, on the spin-liquid mechanism and the influence of various disorders on the physical properties of this system is also discussed., Work in Spain was supported by MICIU (PGC2018-096955-BC44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria deMaeztu (MDM- 2017-0767) Programs and Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). Work in Japan is supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (JP23225005 and JP18H05225).

Non‐centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON2, which shows a polar 6H polytype. Synchrotron X‐ray and neutron powder diffraction, and annular bright‐field in scanning transmission electron microscopy indicate that it crystalizes in the non‐centrosymmetric space group P63mc, with a total order of nitride and oxide at two distinct coordination environments in cubic and hexagonal packed BaX3 layers. A synergetic second‐order Jahn–Teller effect, supported by first principle calculations, anion order, and electrostatic repulsions between W6+ cations, induce large distortions at two inequivalent face‐sharing octahedra that lead to long‐range ordered dipoles and spontaneous polarization along the c axis. The new oxynitride is a semiconductor with a band gap of 1.1 eV and a large permittivity., This work was supported by the Ministerio de Ciencia e Innovación, Spain (MAT2017‐86616‐R, MAT2017‐85232‐R, SEV‐2015‐0496, MDM‐2017‐0767, PGC2018‐096955‐B‐C44 and PGC2018‐093863‐B‐C22) and the Generalitat de Catalunya (2017SGR1377, 2017SGR581, 2017SGR1506 and 2017SGR1289). We thank Alba and ILL (experiments 2018082958 and 5‐23‐721, https://doi.org/10.5291/ILL‐DATA.5‐23‐721) for beam time provision, and Dr. François Fauth for assistance in data collection at Alba. I.F and J.G. acknowledge the Ramon y Cajal contracts RYC‐2017‐22531 and RYC‐2012‐11709. S.C. was supported by FONDECYT, Chile (project 11171063). ICTS‐CNME at UCM is acknowledged for offering access to STEM and expertise.

We report on radical cation salts of EDT-TTF cores bearing a glycine residue with hydrogenosulfate, [HSO4–], or the amphoteric para-carboxybenzenesulfonate, [HO2C-C6H4-SO3–]. In (EDT-TTF-CO-NHCH2-CO2H)2+[HSO4–], orthogonal pairs of oxygen atoms of the tetrahedral sulfonate anions engage in hydrogen bonds building the two-dimensional (2D) chess-board pattern of orthogonal dimers typical of a κ-phase 2D metal. We find by tight-binding and density functional theory analysis of the band structure that, as a result of the structure-directing role of the Gly residue, HOMO···HOMO interactions in (EDT-TTF-CO-NHCH2-CO2H)2+[HSO4–] are twisted away from the usual in-plane isotropy of κ-phases toward a very uncommon quasi-one-dimensional electronic structure with electronic localization. Transport measurements confirm the highly conducting, yet weakly localized regime. The ability of para-carboxybenzenesulfonate to act as a bimolecular, dianionic unit of double spatial extension is fulfilled in (EDT-TTF-CO-NHCH2-CO2H)22+[HO2C-C6H4-SO3–]2, where the charge is balanced by diamagnetic dimers leaving no carrier left available in the lattice., L.Z. and S.S. gratefully acknowledge support from the CNRS and the Region Pays de la Loire for an associated researcher ́ and postdoctoral position, respectively. Financial support from the ANR PNANO Project TTF-Based Nanomat ANR-07- NANO-030-01 is gratefully acknowledged. Work in Spain was supported by MICIU (PGC2018-096955-B-C44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria de Maeztu (MDM2017-0767) Programs and the Generalitat de Catalunya (2017SGR1506 and 2017SGR1289).

Recent interest in potassium-doped p-terphenyl has been fueled by reports of superconductivity at Tc values surprisingly high for organic compounds. Despite these interesting properties, studies of the structure–function relationships within these materials have been scarce. Here, we isolate a phase-pure crystal of potassium-doped p-terphenyl: [K(222)]2[p-terphenyl3]. Emerging antiferromagnetism in the anisotropic structure is studied in depth by magnetometry and electron spin resonance. Combining these experimental results with density functional theory calculations, we describe the antiferromagnetic coupling in this system that occurs in all 3 crystallographic directions. The strongest coupling was found along the ends of the terphenyls, where the additional electron on neighboring p-terphenyls antiferromagnetically couple. This delocalized bonding interaction is reminiscent of the doubly degenerate resonance structure depiction of polyacetylene. These findings hint toward magnetic fluctuation-induced superconductivity in potassium-doped p-terphenyl, which has a close analogy with high Tc cuprate superconductors. The new approach described here is very versatile as shown by the preparation of two additional salts through systematic changing of the building blocks., C.N. thanks Sheldon and Dorothea Buckler for their generous support. Support for this research was provided by the Center for Precision Assembly of Superstratic and Superatomic Solids, an NSF MRSEC (award numbers DMR-1420634 and DMR-2011738), and the Air Force Office of Scientific Research (award number FA9550-18-1-0020). R.H.S. acknowledges support from the Columbia Nano Initiative Postdoctoral Fellowship. X.R. acknowledges support from the NSF CAREER award (NSF DMR-1751949). A.K.B. is supported by the Arnold O. Beckman Fellowship in Chemical Sciences. I.S. is supported by the National Science Foundation under award number CHE-1807654. Single-crystal X-ray diffraction was performed at the Shared Materials Characterization Laboratory at Columbia University, maintained using funding from Columbia University for which we are grateful. Work in Lausanne was supported by the Swiss National Science Foundation. Work in Spain was supported by MICIU (Spain) through Grants PGC2018-096955-B-C44 and PGC2018-093863-B-C22 and Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). E.C. acknowledges support from the Spanish MINECO through the Severo Ochoa Centers of Excellence Program (SEV-2015-0496) and P.A. from the Maria de Maeztu Units of Excellence Program (MDM-2017-0767). S.C. was supported by FONDECYT (Chile) through project 11107163.

Anions have often been considered to act essentially as electron donors or acceptors in molecular conductors. However there is now growing evidence that they play an essential role in directing the structural and hence electronic properties of many of these systems. After reviewing the basic interactions and different ground states occurring in molecular conductors we consider in detail how anions influence the structure of donor stacks and often guide them toward different types of transitions. Consideration of the Bechgaard and Fabre salts illustrates how anions play a crucial role in directing these salts through complex phase diagrams where different conducting and localized states are in competition. We also emphasize the important role of hydrogen bonding and conformational flexibility of donors related to BEDT-TTF and we discuss how anions have frequently a strong control of the electronic landscape of these materials. Charge ordering, metal to metal and metal to insulator transitions occurring in these salts are considered., Work in Spain was supported by MINECO (Spain) through Grants FIS2015-64886-C5-4-P and CTQ2015-64579-C3-3-P, and Generalitat de Catalunya (2017SGR1506, 2017SGR1289 and XRQTC). E. C. acknowledges support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496. This review is based on recent collaborative works and pertinent discussions with N. Avarvari, P. Batail, C. Bourbonnais, C. Coulon, M. de Souza, M. Dressel, M. Fourmigue´, P. Foury-Leylekian, V. Ilakovac, D. Je´rome, M. Lang, E. Molins, Y. Nogami, C. Pasquier, H. Sawa and S. Tomic´.

Four new Ir(III) complexes with the general formula [IrHCl(C^N)(PPh3)2] containing different conjugated Schiff base ligands (C^N) have been synthesized and characterized by 1H, 13C, and 31P NMR, HRMS, and IR spectra and one of them by single crystal X-ray diffraction. Their photophysical properties in solution and in the solid state have been analyzed and three main practical results have been obtained: (i) a dual fluorescent and phosphorescent emissive complex in solution, (ii) successful acid/base sensing in the solid state and (iii) quantitative CO2 detection. Quantum chemical calculations have been employed to assign the character of the lowest excited states. A plausible explanation for the observed aggregation induced enhanced emission (AIEE) is given, based on the restriction of intramolecular motions due to the effect of intermolecular C–H⋯π and C–H⋯Cl type interactions upon aggregation.

Here, the first accurate study is presented of the room-temperature and 100 K structures of one of the first organic spin liquids, κ-(BEDT-TTF)

The electronic structure of AgCuO2, and more specifically the possible charge delocalization and its implications for the transport properties, has been the object of debate. Here the problem is faced by means of first-principles density functional theory calculations of the electron and phonon band structures as well as molecular dynamics simulations for different temperatures. It is found that both Cu and Ag exhibit noninteger oxidation states, in agreement with previous spectroscopic studies. The robust CuO2 chains impose a relatively short contact distance to the silver atoms, which are forced to partially use their dz2 orbitals to build a band. This band is partially emptied through overlap with a band of the CuO2 chain, which should be empty if copper were in a Cu3+ oxidation state. In that way, although structural correlations could roughly be consistent with an Ag+Cu3+O2 formulation, the appropriate oxidation states for the silver and copper atoms become Ag(1+δ)+ and Cu(3−δ)+, and as a consequence, the stoichiometric material should be metallic. The study of the electronic structure suggests that Ag atoms form relatively stable chains that can easily slide despite the linear coordination with oxygen atoms of the CuO2 chains. Phonon dispersion calculations and molecular dynamics simulations confirm the stability of the structure although pointing out that sliding of the silver chains is an easy motion that does not lead to substantial modifications of the electronic structure around the Fermi level and, thus, should not alter the good conductivity of the system. However, this sliding of the silver atoms from the equilibrium position explains the observed large thermal factors., This work was supported by MINECO (Spain) through Grant Nos. FIS2015-64886-C5-4-P, RTI2018-097753-B-I00, CTQ2015-64579-C3-3-P, and MAT2015-65192-R, Generalitat de Catalunya (2017SGR1506, 2017SGR1289, and XRQTC), and FONDECYT (Chile) through Project No. 11107163. E.C., N.C.-P., and A.G. acknowledge support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant No. SEV-2015-0496, and P.A. is supported from the Maria de Maeztu Units of Excellence Program under Grant No. MDM-2017-0767.

The electronic structure of AgCuO

We report anomalies observed in photoelectron spectroscopy measurements performed on α-(BEDT-TTF)2I3 crystals. In particular, above its metal-insulator transition temperature (T = 135 K), we observe the lack of a sharp Fermi edge in contradiction with the metallic transport properties exhibited by this quasi-bidimensional organic material. We interpret these unusual results as a signature of a one-dimensional electronic behavior confirmed by DFT band structure calculations. Using photoelectron spectroscopy we probe a Luttinger liquid with a large correlation parameter (α > 1) that we interpret to be caused by the chain-like electronic structure of α-(BEDT-TTF)2I3 surface doped by iodine defects. These new surface effects are inaccessible by bulk sensitive measurements of electronic transport techniques., We acknowledge A. Santander-Syro, M. Gabay and P. Auban- Senzier for fruitful discussions. Work in Spain was supported by the Spanish Ministerio de Econom a y Competitividad (Grants FIS2015-64886-C5-4-P and CTQ2015-64579-C3-3-P) and Generalitat de Catalunya (2017SGR1506, 2017SGR1289 and XRQTC). E.C. acknowledges support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496. P.A. acknowledges support from the Maria de Maeztu Units of Excellence Program under Grant MDM-2017-0767.

We present detailed studies of the high-field magnetoresistance of the layered organic metal $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}\mathrm{Mn}{[\mathrm{N}{(\mathrm{CN})}_{2}]}_{3}$ under a pressure slightly above the insulator-metal transition. The experimental data are analyzed in terms of the Fermi surface properties and compared with the results of first-principles band structure calculations. The calculated size and shape of the in-plane Fermi surface are in very good agreement with those derived from Shubnikov-de Haas oscillations as well as the classical angle-dependent magnetoresistance oscillations. A comparison of the experimentally obtained effective cyclotron masses with the calculated band masses reveals electron correlations significantly dependent on the electron momentum. The momentum- or band-dependent mobility is also reflected in the behavior of the classical magnetoresistance anisotropy in a magnetic field parallel to layers. Other characteristics of the conducting system related to interlayer charge transfer and scattering mechanisms are discussed based on the experimental data. Besides the known high-field effects associated with the Fermi surface geometry, new pronounced features have been found in the angle-dependent magnetoresistance, which might be caused by coupling of the metallic charge transport to a magnetic instability in proximity to the metal-insulator phase boundary.

We present a computational study of a reduced potential energy surface (PES) to describe enantiomerization and internal rotation in three triptycyl-n-helicene molecules, centering the discussion on the issue of a proper reaction coordinate choice. To reflect the full symmetry of both strongly coupled enantiomerization and rotation processes, two non-fixed combinations of dihedral angles must be used, implying serious computational problems that required the development of a complex general algorithm. The characteristic points on each PES are analyzed, the intrinsic reaction coordinates are calculated, and finally they are projected on the reduced PES. Unlike what was previously found for triptycyl-3-helicene, the surfaces for triptycyl-4-helicene and triptycyl-5-helicene contain valley-ridge-inflection (VRI) points. The reaction paths on the reduced surfaces are analyzed to understand the dynamical behaviour of these molecules and to evaluate the possibility of a molecule of this family exhibiting a Brownian ratchet behaviour.

In the last decades, compounds with ‘Aggregation-Induced Emission’ (AIE), which are weakly or non-emissive at all in solution but exhibit a strong luminescence in aggregated states, have emerged as an extraordinary breakthrough in the field of luminescent materials, allowing to circumvent ‘Aggregation Caused Quenching’ (ACQ), which in many cases prevents the development of efficient solid-state materials for optoelectronic applications. Since the discovery of AIE, many AIE-active materials have been developed, most of them composed of organic molecules, and thus fluorescent in nature. Although a wide range of applications such as bioimaging, sensing, multi-stimuli responsive materials, and optoelectronic devices have been proposed for this new class of materials, triplet harvesting phosphorescent materials have much longer lifetimes as compared to their singlet harvesting analogues, and for this particular reason, the development of AIE-active phosphorescent materials seems to be a promising strategy from the applications point of view. In this respect, the synthesis of new AIE-active systems including heavy metals that would facilitate the population of low-lying excited triplet states via spin-orbit coupling (SOC), for which the strength increases as the fourth power of atomic number, i.e. Z4, is highly desirable. This review covers the design and synthetic strategies used to obtain the AIEgens reported in the literature that contain either d-block metals such as Cu(I), Zn(II), Re(I), Ru(II), Pd(II), Ir(III), Pt(II), Au(I), and Os(IV), describing the mechanisms proposed to explain their AIE. New emerging high-tech applications such as OLEDs, chemical sensors or bioimaging probes proposed for these materials are also discussed in a separate section.

In materials with nearly commensurate band filling the electron liquid may spontaneously separate into components with distinct properties, yielding complex intra- and interunit cell ordering patterns and a reduced dimensionality. Polarization-dependent angle-resolved photoemission data with submicron spatial resolution demonstrate such an electronic self-organization in NbSe3, a compound considered to be a paradigm of charge order. The new data indicate the emergence of a novel order, and reveal the one-dimensional (1D) physics hidden in a material which naively could be considered the most three dimensional of all columnar chalcogenides. The 1D physics is evidenced by a new selection rule—in two polarizations we observe two strikingly different dispersions each closely resembling apparently contradicting results of previous studies of this material., The work at Lausanne and Geneva is supported by the Swiss NSF. M.A.V. acknowledges financial support from Spanish MICIN Postdoctoral Mobility Program. S.P. acknowledges C’NANO Ile-de-France, DIM NanoK, for the support of the Nanospecs project. Work in Spain was supported by a MINECO (Grants FIS2015-64886-C5-4-P and CTQ2015-64579-C3-3-P), Generalitat de Catalunya (2017SGR1506 and 2017SGR1289), and XRQTC. E.C. acknowledges support from MINECO through the Severo Ochoa Centers of Excellence Program under Grant No. SEV-2015-0496. ICN2 is funded by the CERCA Program/ Generalitat de Catalunya, and supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV- 2017-0706). P.A. acknowledges support from the Maria de Maeztu Units of Excellence Program under Grant MDM- 2017-0767. S.C. gratefully acknowledges the Becas Chile program (CONICYT PAI/INDUSTRIA 72090772) for a doctoral grant at the Universitat de Barcelona. Synchrotron SOLEIL is supported by the Centre National de la Recherche Scientifique (CNRS) and the Commissariat à l’Energie Atomique et aux energies Alternatives (CEA).

A 1 : 1 metallic charge-transfer salt is obtained by cosublimation of (Z,E)-(SMe)2Me2TTF and TCNQ. X-ray diffraction studies confirm the formation of segregated stacks comprising donor and acceptor molecules in [(E)-(SMe)2Me2TTF](TCNQ). The crystal packing features lateral S⋯S interactions between TTF stacks, which is in sharp contrast to that in (TTF)(TCNQ). Structural analysis and theoretical studies afford a partial charge-transfer (ρ ≈ 0.52), leading to a system with the electronic structure close to quarter-filled. Resistivity measurements reveal that this material behaves as a metal down to 56 K and 22 K at 1 bar and 14.9 kbar, respectively. The thermopower is negative in the metallic regime, indicating the dominant role of the acceptor stacks for the observed conducting behavior. Analysis of single-crystal EPR spectra shows the remaining spin susceptibility at 4.3 K, suggesting the importance of the Hubbard U correction. These results highlight the judicious engineering of electronic and geometrical effects on the TTF core; the combined use of methyl and thiomethyl groups has decreased the TCNQ bandwidth while maintaining the segregated stacks, converting the metal to insulator (M–I) transition to more 4kF like. In addition, the enhanced S⋯S contacts between the TTF stacks lead to more rapidly decreasing M–I transition temperature under various pressures., This research was supported by the French National Research Agency Grants, ANR 16-ACHN-0007 and ANR 17-ERC3-0003, and a PhD grant (to M. Beau) from the Bretagne region. Y. Kiyota is grateful to JSPS for a research fellowship (17J05098). We thank Dr A. Vacher (Rennes) for the preparation of (Z,E)-(SCH2CH2CN)2(Me)2TTF and CDIFX-Rennes for access to the X-ray diffractometer. Work in Spain was supported by MICIU (PGC2018-096955-B-C44 and PGC2018-093863-B-C22), MINECO through the Severo Ochoa (SEV-2015-0496) and Maria de Maeztu (MDM-2017-0767) Programs and the Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). Work in Japan was supported by JPSJ KAKENHI (Grant Number 16K13974 and 18H02044) and the Takahashi Industrial and Economic Research Foundation.

Optimization by first principles DFT-based electronic structure methods of the crystal structures for the five polymorphs of Y2WO6 reported in the literature yields results in good agreement with those determined experimentally by X-ray diffraction. The monoclinic P2/c phase appears to be the most stable one at ambient conditions, although high temperature orthorhombic phases with larger molar volumes could be favoured upon replacement of Y3+ cations by larger Ln3+ ones, and hence, provide plausible structures for Y2WO6:Ln3+ phosphors at ambient conditions. For all polymorphs the top of the valence band is dominated by O2p orbitals with a relatively narrow WO6-centred conduction band appearing just below a broad Y4d-centred band. Insertion energies for Eu3+ replacing Y3+ are estimated to be in the range of 3–4 eV per cation, with the smaller values corresponding to substitutions into the larger octacoordinated Y3+ sites.

We present high-resolution near-edge X-ray absorption fine structure (NEXAFS) measurements at the P L2/3-edges, F K-edge, C K-edge and Se M2/3-edges of the quasi-one-dimensional (1D) conductor and superconductor (TMTSF)2PF6. NEXAFS allows probing the donor and acceptor moieties separately; spectra were recorded between room temperature (RT) and 30 K at normal incidence. Spectra taken around RT were also studied as a function of the angle (θ) between the electric field of the X-ray beam and the 1D conducting direction. In contrast with a previous study of the S L2/3-edges spectra in (TMTTF)2AsF6, the Se M2/3-edges of (TMTSF)2PF6 do not exhibit a well resolved spectrum. Surprisingly, the C K-edge spectra contain three well defined peaks exhibiting strong and non-trivial θ and temperature dependence. The nature of these peaks as well as those of the F K-edge spectra could be rationalized on the basis of first-principles DFT calculations. Despite the structural similarity, the NEXAFS spectra of (TMTSF)2PF6 and (TMTTF)2AsF6 exhibit important differences. In contrast with the case of (TMTTF)2AsF6, the F K-edge spectra of (TMTSF)2PF6 do not change with temperature despite stronger donor-anion interactions. All these features reveal subtle differences in the electronic structure of the TMTSF and TMTTF families of salts., Work in Spain was supported by MINECO (Spain) through Grants FIS2012-37549-C05-05, FIS2015-64886-C5-4-P and CTQ2015-64579-C3-3-P, and Generalitat de Catalunya (2014SGR301 and XRQTC). E.C. acknowledges support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496. Special thanks are due to Graduate School of Excellence MAINZ and to Transregio SFB TR49. The crystals were synthesized by the late A. Moradpour. We would like to thank to MAX IV laboratory for providing beam time at I1011 beam line.

In the present work we perform a computational study of the properties of a push-pull organic dye with a quinoidal thiophene unit as the conjugated linker between the electron donor and acceptor groups. We investigate the photophysical properties of the dye related to its potential use as a molecular sensitizer in dye-sensitized solar cells. We rationalize the solvation effects on the absorption band of the dye in protic and aprotic solvents, identifying the interaction of alcohol solvents with the amine in the donor group as the source for the blue shift of the absorption band with respect to aprotic solvents.

A new cationic iridium(III) complex exhibiting “aggregation induced emission (AIE)” activity, [Ir(PPh3)2(bipy)(H)2]A (bipy = 2,2′-bipyridine; A = counterions), has been synthesized in a straightforward synthetic route. Interestingly, the emission color of solid state samples of this complex varied with different counteranions [A = Cl–, BF4–, PF6–, N(CN)2–] and crystallization induced emission was observed. The emission properties for the compounds with A= Cl–, PF6– are discussed by analyzing the crystal packing, the frontier molecular orbitals, and the calculation of the relevant low-lying excited states using time-dependent density functional theory. The restriction of internal rotation of the phenyl rings in the phosphine ligands due to intermolecular interactions is suggested as the most plausible origin of the observed AIE effect in these crystals.

The first examples of chiral single component conductors are reported. Both (S,S) and (R,R) enantiomers of 5,6-dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligand have been used to prepare anionic metal bis(dithiolene) complexes formulated as ([(n-Bu)4N][M(dm-dddt)2] (M = Au, Ni), which are isostructural according to single crystal X-ray analysis. Single crystal transport measurements indicate semiconducting behavior for the anionic radical Ni complexes, with low room temperature conductivity values and high activation energies. Electrocrystallization experiments provided neutral [M(dm-dddt)2] (M = Au, Ni) complexes. The neutral radical gold compounds show intermolecular S···S interactions in the solid state giving rise to layers interconnected through weak C–H···S hydrogen bonds. The most peculiar structural feature concerns a dissymmetry between the two dithiolene moieties, while the nickel counterpart is symmetric. Single crystal resistivity measurements show thermally activated behavior for the open-shell gold complexes, with room temperature conductivity values of 0.02–0.04 S·cm–1 and activation energies strongly influenced by hydrostatic pressure. A thorough theoretical study on nickel anion radical and gold neutral radical bis(dithiolene) complexes applied to the chiral complexes [M(dm-dddt)2] (M = Au, Ni–) and to a series of previously reported compounds addressed the issue of symmetry versus asymmetry from an electronic coupling perspective between the two dithiolene ligands. It results that neutral gold complexes with dithiolene ligands without extended delocalization are Class II mixed-valent compounds in the Robin and Day classification, presenting an inherent tendency toward asymmetric structures, which can be however modulated by the intermolecular organization in the solid state., This work was supported in France by the National Agency for Research (ANR Inter, ANR-12-IS07-0004-04, CREMM Project), the Region Pays de la Loire (grant for D.B.), the CNRS, the University of Angers, the University of Bordeaux and the Aquitaine Region. Work in Spain was supported by the Spanish Ministerio de Economía y Competitividad (Grants FIS2012- 37549-C05-05, FIS2015-64886-C5-4-P and CTQ2015-64579- C3-3-P) and Generalitat de Catalunya (2014SGR301 and XRQTC). E.C. acknowledges support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496.

The mixed-valence FeIIFeIII 2D coordination polymer formulated as [TAG][FeIIFeIII(ClCNAn)3]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn2− = chlorocyanoanilate dianionic ligand) crystallized in the polar trigonal space group P3. In the solid-state structure, determined both at 150 and at 10 K, anionic 2D honeycomb layers [FeIIFeIII(ClCNAn)3]− establish in the ab plane, with an intralayer metal−metal distance of 7.860 Å, alternating with cationic layers of TAG. The similar Fe−O distances suggest electron delocalization and an average oxidation state of +2.5 for each Fe center. The cation imposes its C3 symmetry to the structure and engages in intermolecular N−H···Cl hydrogen bonding with the ligand. Magnetic susceptibility characterization indicates magnetic ordering below 4 K and the presence of a hysteresis loop at 2 K with a coercive field of 60 Oe. Mössbauer measurements are in agreement with the existence of Fe(+2.5) ions at RT and statistic charge localization at 10 K. The compound shows semiconducting behavior with the in-plane conductivity of 2 × 10−3 S/cm, 3 orders of magnitude higher than the perpendicular one. A small-polaron hopping model has been applied to a series of oxalate-type FeIIFeIII 2D coordination polymers, providing a clear explanation on the much higher conductivity of the anilate-based systems than the oxalate ones., The work in France was supported by the CNRS, the University of Angers, the Erasmus program (mobility grant to N.M.), the RFI Regional project LUMOMAT (grant to A.A., project ASCO MMM), and the PIA project “Lorraine Université d'Excellence” (reference ANR-15-IDEX-04-LUE). This work was supported in Italy by the Fondazione di Sardegna-Convenzione triennale tra la Fondazione di Sardegna e gli Atenei Sardi, Regione Sardegna-L.R. 7/2007 annualità 2016-DGR 28/21 del 17.05.2015 “Innovative Molecular Functional Materials for Environmental and Biomedical Applications” and INSTM. Work in Spain was supported by the Spanish Ministerio de Economi ́ a y Competitividad (Grants FIS2012-37549-C05-05, FIS2015-64886-C5-4-P, CTQ2015- 64579-C3-3-P, and CTQ2015-71287-R) and Generalitat de Catalunya (2014SGR301, 2017SGR797, and XRQTC and the CERCA program). E.C. acknowledges support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496. J.C.W. and B.J.C.V. acknowledge Fundaca̧ o para a Cie ̃ ncia e a Tecnologia (FCT, ̂ Portugal) through the project UID/Multi/04349/2013.

Advanced biomedical research has established that cancer is a multifactorial disorder which is highly heterogeneous in nature and responds differently to different treatment modalities, due to which constant monitoring of therapy response is becoming extremely important. To accomplish this, different theranostic formulations have been evaluated. However, most of them are found to suffer from several limitations extending from poor resolution, radiation damage, to high costs. In order to develop a better theranostic modality, we have designed and synthesized a novel platinum(ii)-based 'aggregation induced emission' (AIE) molecule (named BMPP-Pt) which showed strong intra-cellular fluorescence and also simultaneously exhibited potent cytotoxic activity. Due to this dual functionality, we wanted to explore the possibility of using this compound as a single molecule based theranostic modality. This compound was characterized using elemental analysis, NMR and IR spectroscopy, mass spectrometry and single crystal X-ray structure determination. BMPP-Pt was found to exhibit a high AIE property with emission maxima at 497 nm. For more efficient cancer cell targeting, BMPP-Pt was encapsulated into mesoporous silica nanoparticles (Pt-MSNPs) and the MSNPs were further surface modified with an anti-EpCAM aptamer (Pt-MSNP-E). Pt-MSNPs exhibited higher intracellular fluorescence compared to free BMPP-Pt, though both of them induced a similar degree of cell death via the apoptosis pathway, possibly via cell cycle arrest in the G1 phase. Anti-EpCAM aptamer modification was found to increase both cytotoxicity and intracellular fluorescence compared to unmodified MSNPs. Our study showed that EpCAM functionalized BMPP-Pt loaded MSNPs can efficiently internalize and induce apoptosis of cancer cells as well as show strong intracellular fluorescence. This study provides clues towards the development of a potential single compound based theranostic modality in future.

Foury-Leylekian, Pascale et al., We present here the first accurate determination of the exact structure of κ-(BEDT-TTF)2Cu2(CN)3. Not only did we show that the room temperature structure used over the last twenty years was incorrect, but we were also able to correctly and precisely determine it. The results of our work provide evidence that the structure presents a triclinic symmetry with two non-equivalent dimers in the unit cell, which implies a charge disproportionation between the dimers. However, structural refinement shows that the charge disproportionation is quite weak at room temperature., We thank Joon I. Jang for his work related to SHG measurements. S.T. acknowledges the support by the Croatian Science Foundation project IP-2013-11-1011. Work in Spain was supported by the Spanish Ministerio de Economía y Competitividad (Grants FIS2015-64886-C5-4-P and CTQ2015-64579-C3-3-P) and Generalitat de Catalunya (217SGR1506 and XRQTC). E.C. acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496.

Despite its undeniable problems from a philosophical point of view, the concept of molecular structure, with attributes such as shape and symmetry, directly borrowed from the description of macroscopic objects, is nowadays central to most of the chemical sciences. Descriptions such as "the tetrahedral carbon atom" or "octahedral coordination complexes" are widely used as much in elementary textbooks as in the most up-to-date research articles. The definition of molecular shape is, however, not as simple as it might seem at first sight. Molecules don't behave as macroscopic objects do, and the arrangement of atoms within a molecule changes continuously due to the incessant motion of its constituent particles, nuclei, and electrons. How are molecular shape and symmetry affected by this thermal motion? In this Minireview, we introduce the language of continuous symmetry measures as a new tool to quantitatively describe the effects of temperature on molecular shape and symmetry, enriching in this way the set of molecular descriptors that might be used in the establishment of new empirical structure-property relations, of great interest in concomitant areas such as medicinal chemistry or materials science.