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We present a novel approach to second harmonic microscopy combining variable temperature and photon counting. This innovative method aims to generate Second Harmonic Generation (SHG) images by scanning the same area multiple times with short pixel dwell times and low excitation intensities, as illustrated by imaging the full extent of a single crystalline rod of (1,4-bis((4′-(iodoethynyl)phenyl) ethynyl) bicyclo[2.2.2]octane (BCO). Remarkably, this new technique records the change in SHG intensity that occurs along with the crystalline phase transition at 108 K, thereby showing great promise in exploring the intricate instabilities of rotator dynamics concealed within the phase diagrams of molecular machines. Notably, our findings reveal a sustained decrease in non-linear optical intensity as the temperature drops to 95 K, followed by a sharp increase in SHG intensity at approximately 108 K, in synchronicity with the phase transition reported earlier that involves an intricate set of concerted changes in rotor dynamics. [ABSTRACT FROM AUTHOR]

We have investigated the infrared spectra of the quarter-filled charge-ordered insulators δ-(EDTTTF- CONMe2)2X (X= AsF6, Br) along all three crystallographic directions in the temperature range from 300 to 10 K. DFT-assisted normal mode analysis of the neutral and ionic EDT-TTF-CONMe2 molecule allows us to assign the experimentally observed intramolecular modes and to obtain relevant information on the charge ordering and intramolecular interactions. From frequencies of chargesensitive vibrations we deduce that the charge-ordered state is already present at room temperature and does not change on cooling, in agreement with previous NMR measurements. The spectra taken along the stacking direction clearly show features of vibrational overtones excited due to the anharmonic electronic molecule potential caused by the large charge disproportionation between the molecular sites. The shift of certain vibrational modes indicates the onset of the structural transition below 200 K. [ABSTRACT FROM AUTHOR]

The exotic properties of quantum spin liquids (QSLs) have continually been of interest since Anderson's 1973 ground-breaking idea. Geometrical frustration, quantum fluctuations, and low dimensionality are the most often evoked material's characteristics that favor the long-range fluctuating spin state without freezing into an ordered magnet or a spin glass at low temperatures. Among the few known QSL candidates, organic crystals have the advantage of having rich chemistry capable of finely tuning their microscopic parameters. Here, we demonstrate the emergence of a QSL state in [EDT-TTF-CONH2]+ 2 [BABCO] (EDT-BCO), where the EDT molecules with spin-1/2 on a triangular lattice form layers which are separated by a sublattice of BCO molecular rotors. By several magnetic measurements, we show that the subtle random potential of frozen BCO Brownian rotors suppresses magnetic order down to the lowest temperatures. Our study identifies the relevance of disorder in the stabilization of QSLs. [ABSTRACT FROM AUTHOR]

We report a facile desymmetrization of 1,4‐diethynylbicyclo[2.2.2]octane. One of the acetylene termini was protected by TMS and the desired product was purified by sublimation. It is stable but reactive, as shown by the synthesis of a complex pyridine‐terminated molecular rod containing both a bicyclo[1.1.1]pentane and a bicyclo[2.2.2]octane cage. Six crystal structures of key intermediates are presented. Facile desymmetrization of 1,4‐diethynylbicyclo[2.2.2]octane based on TMS protection of one of the acetylene termini followed by sublimation of the desired product is presented. The reactivity of this derivative was demonstrated in the synthesis of a complex pyridine‐terminated molecular rod containing both a bicyclo[1.1.1]pentane and a bicyclo[2.2.2]octane cage. [ABSTRACT FROM AUTHOR]

Electrocrystallization of the (S,S,S,S) enantiomer of tetramethyl-bis(ethylenedithio)-tetrathiafulvalene donor 1 in the presence of the dianionic hexanuclear rhenium (III) cluster [Re6S6Clg]2- affords a crystalline radical cation salt formulated as [(S)-1]2⋅Re6S6Cl8, in which the methyl substituents of the donors adopt an unprecedented all-axial conformation. A complex set of intermolecular TTF⋯TTF and cluster⋯TTF interactions sustain an original tridimensional architecture. [ABSTRACT FROM AUTHOR]

Variable-temperature (VT) crystal structures, VT 1H spin–lattice relaxation in static crystals, and DFT modelling of the rotational barriers of BCP rotators in crystalline arrays of a rod-like molecule containing two 1,3-bis(ethynyl)bicyclo[1.1.1]pentane (BCP) units demonstrate that a correlated gearing motion occurs in the limit of a weak coupling between two rotors in a pair. [ABSTRACT FROM AUTHOR]

We report on the structures of three dibromothiophene compounds (4, 5, and 12) and the analysis of the patterns of self-assembly in the solid state by C-- Br--Br--C halogen bonds of a selected set of 16 di- or poly-bromine-- (poly)thiophene monomers sorted according to the dimensionality of their halogen-bonded, extended frameworks thereby identifying syn- or anti-strings and layers. We conclude that in 1, 2, 9, and 10, the antiparallel orientation of successive C-- Br--Br--C halogen-bonded dibromothiophene units along extended anti-strings is linked to the occurrence of solid-state polymerization. [ABSTRACT FROM AUTHOR]

We report on the structures of three dibromothiophene compounds (4, 5, and 12) and the analysis of the patterns of self-assembly in the solid state by C-- Br--Br--C halogen bonds of a selected set of 16 di- or poly-bromine-- (poly)thiophene monomers sorted according to the dimensionality of their halogen-bonded, extended frameworks thereby identifying syn- or anti-strings and layers. We conclude that in 1, 2, 9, and 10, the antiparallel orientation of successive C-- Br--Br--C halogen-bonded dibromothiophene units along extended anti-strings is linked to the occurrence of solid-state polymerization. [ABSTRACT FROM AUTHOR]

We report on the synthesis and application of a 2 nm long, curved ditopic biscarboxylic ligand with a 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotator core and an helical twist to the construction of an extended single-crystalline framework solid with paddlewheel hinges, [CuII]2[1,4-bis(carboxyphenyl ethynyl)bicyclo[2.2.2]octane]2(H2O)2 or [CuII]2(bbcbco)2(H2O)2. The interconnection of interpenetrated square lattices involves short rotor-rotor H ···H interactions (1.9 to 2.4 Å) such that the moving parts are expected to rub onto each other in the lattice in a Brownian rotational motion with a calculated rotational barrier of 3.7 kcal ·mol-1. Variable-temperature 1H spin-lattice relaxation ( T1) experiments carried out on a static crystalline sample did not provide however a value of this rotational barrier because the relaxation proved to be dominated by the coupling of the moving protons to the electronic spins of the CuII dimers. Remarkably, we reveal how the singlet-triplet spin dynamics of non-interacting CuII dimers is elegantly characterized by solid state NMR spectroscopic experiments yielding an exchange coupling constant, Jexp = -365 K = -254 cm-1, in good agreement with theoretical estimations and experimental data on related CuII dimer systems. [ABSTRACT FROM AUTHOR]

We report on a polymorph (2) of an amphidynamic crystal of molecular rods with two helical 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators where half of the rod-like molecules appear to be shifted with respect to their closest neighbours. This translation takes cogwheel-like pairs of rotators apart in the lattice in such a way that their motion becomes uncorrelated. This property is to be contrasted with the highly correlated motion found to govern the rotators in a recently-published polymorph 1 of the same material. As with polymorph 1, this motion is shown to take place independently of mutations in the handedness of the rotators and of the 'mutamer'-induced second harmonic generation. [ABSTRACT FROM AUTHOR]

Unconventional superconductivity typically occurs in materials in which a small change of a parameter such as bandwidth or doping leads to antiferromagnetic or Mott insulating phases. As such competing phases are approached, the properties of the superconductor often become increasingly exotic. For example, in organic superconductors and underdoped high-Tc cuprate superconductors a fluctuating superconducting state persists to temperatures significantly above Tc. By studying alloys of quasi-two-dimensional organic molecular metals in the κ-(BEDT-TTF)2X family, we reveal how the Nernst effect, a sensitive probe of superconducting phase fluctuations, evolves in the regime of extreme Mott criticality. We find strong evidence that, as the phase diagram is traversed through superconductivity towards the Mott state, the temperature scale for superconducting fluctuations increases dramatically, eventually approaching the temperature at which quasiparticles become identifiable at all. [ABSTRACT FROM AUTHOR]

The synthesis and full characterization (including X-ray structures) of two redox-active terpyridine–tetrathiafulvalene ligands namely (4′-amido-2,2′:6′,2′′-terpyridyl)-6,7-ethylenedithiotetrathiafulvalene (1) and 2-(4′-thioacetamide-2,2′:6′,2′′-terpyridyl)-3,6,7-tris(methylsulfanyl)-6,tetrathiafulvalene (2) are described. The binding properties of these multifunctional systems for various transition metal cations (Ni2+, Zn2+, Cd2+ and Fe2+) are analyzed in solution by cyclic voltammetry and UV-visible spectroscopy. In addition, a tetrahedral neutral zinc metal complex of ligand (2) formulated as (MeS)3-TTF-SCH2CONH-Tpy-ZnCl2·MeOH [complex (3)] and an octahedral nickel complex formulated as [{(MeS)3-TTF-SCH2CONH-Tpy}2Ni]·(ClO4)2·0.5(H2O) [complex (4)] are characterized in the solid state by X-ray diffraction. [ABSTRACT FROM AUTHOR]

We report on a series of amino acid derivatives of tetrathiafulvalene as well as on the structure-directing abilities of their peptide residues in the crystalline solid state to stabilize patterns of interactions such as β strands and sheet motifs. Characteristic hydrogen-bonding motifs are indeed identified within ethylenedithiotetrathiafulvalene (EDT-TTF) and dimethyltetrathiafulvalene (Me2-TTF) based compounds 1- 5. Esters 1- 3 contain hydrogen-bond acceptors, namely carbonyl groups, as well as one strong (NH) and one weak (C [ABSTRACT FROM AUTHOR]

The concomitant use of polycationic dendrimers and cationic surfactants for the elaboration of periodic mesoporous silica of type MCM-41 is described. The hexagonal structure is preserved up to about 26% in weight of dendrimer included in the silica. The cationic surfactant can be selectively removed to liberate the pores, while preserving the non-covalently incorporated dendrimers. These dendrimers included in the mesoporous silica are fully accessible through the mesoporous volume to small molecules such as HCl and tetrahydrofuran. [ABSTRACT FROM AUTHOR]

Describes a lyotropic liquid-crystalline lamellar phase comprising an aqueous dispersion of planar solid-like layers of covalently bonded phosphatoantimonate. Mechanical or magnetic alignment of the materials over large pH and temperature ranges; Application in measuring residual dipolar couplings for the structure determination of biomolecules by liquid-state nuclear magnetic spectroscopy.

Studies the crystal structures of bis(tetraphenylphosphonium) bis[cis-1,2-bis(methoxycarbonyl)ethlene-dithiolato-Kappa[sup 2]S,S' nickelate(II) and bis(tetraphenylphosphonium) bis[cis-1,2-bis(methoxycarbonyl)ethylene-dithiolato-Kappa[sup 2]nickelate(III) iodide. Location of the nickel atoms; Paramagnetic complexes.

Two‐dimensional (2D) van der Waals materials with in‐plane anisotropy are of great interest for directional transport of charge and energy, as exemplified by recent studies on black phosphorus and α‐phase molybdenum trioxide (α‐MO3). Here, a layered van der Waals semiconductor with in‐plane anisotropy built upon the superatomic units of Mo6S3Br6 is reported. This material possesses robust 2D characteristics with a direct gap of 1.64 eV, as determined by scanning tunneling spectroscopy and first‐principles calculations. Polarization‐dependent Raman spectroscopy measurement and density functional theory calculation reveal strong in‐plane anisotropy. These results suggest an effective strategy to explore anisotropic 2D electronic and optoelectronic properties from superatomic building blocks with multifunctionality, emergent properties, and hierarchical control. [ABSTRACT FROM AUTHOR]

In the title compound, (C10H9NOS6)K[Hg(SCN)4] or (EDT–TTF–CONHMe)K[Hg(SCN)4)], fully oxidized organic (EDT–TTF–CONHMe)+· radical cations form quasi-one-dimensional stacks running along the monoclinic 21 axis and alternating along the crystallographic [101] direction with inorganic anion stacks made from mixed K+–[Hg(SCN)4]2− ribbons. For each anion, three essentially collinear SCN ligands inter­act with the K+ ions via short N⋯K contacts, while the terminal N atom of the fourth SCN group is engaged in a number of hydrogen-bond contacts with the –CH, –NH and –CH2 hydrogen-bond donors of the amide function. Radical cations are dimerized along the stacks and the crystal conductivity is activated. [ABSTRACT FROM AUTHOR]