Synthesis, structure and Hirshfeld surface analysis of 2-oxo-2-chromen-6-yl 4--butyl-benzoate: work carried out as part of the AFRAMED project.

In the title compound, CHO, the dihedral angle between the 2-chromen-2-one ring system and the phenyl ring is 89.12 (5)°. In the crystal, the mol-ecules are connected through C-H⋯O hydrogen bonds to generate [010] double chains that are reinforced by weak aromatic π-π stacking inter-actions.

Investigation of the Binary System of Proxyphylline Enantiomers: Structural Resolution and Phase Diagram Determination.

The solid-state landscape of proxyphylline (PXL), a chiral derivative of theophylline crystallizing as a racemic compound, was extensively investigated by means of thermal analyses and diffraction techniques. This study revealed the presence of five distinct polymorphic forms that were characterized: two polymorphs of the racemic mixture and three polymorphs of the pure enantiomer. The nature of each solid phase was confirmed by combining the different analytical techniques, revealing the presence of a thermodynamically stable racemic compound, RI (= 134 °C), in equilibrium with the stable enantiopure crystal form, EI ( = 148.

Role and Effect of Meso-Structuring Surfactants on Properties and Formation Mechanism of Microfluidic-Enabled Mesoporous Silica Microspheres.

We have shown in a previous work that the combination of the emulsion solvent evaporation technique and droplet-based microfluidics allows for the synthesis of well-defined monodisperse mesoporous silica microcapsules (hollow microspheres), whose size, shape and composition may be finely and easily controlled. In this study, we focus on the crucial role played by the popular Pluronic P123 surfactant, used for controlling the mesoporosity of synthesised silica microparticles. We show in particular, that although both types of initial precursor droplets, prepared with and without P123 meso-structuring agent, namely P123 and P123 droplets, have a similar diameter (≃30 μm) and a similar TEOS silica precursor concentration (0.

Structural Properties of Metal-Organic Frameworks at Elevated Thermal Conditions via a Combined Density Functional Tight Binding Molecular Dynamics (DFTB MD) Approach.

The performance of different density functional tight binding (DFTB) methods for the description of six increasingly complex metal-organic framework (MOF) compounds have been assessed. In particular the self-consistent charge density functional tight binding (SCC DFTB) approach utilizing the 3ob and matsci parameter sets have been considered for a set of four Zn-based and two Al-based MOF systems. Moreover, the extended tight binding for geometries, frequencies, and noncovalent interactions (GFN2-xTB) approach has been considered as well.

X-ray scattering study of water confined in bioactive glasses: experimental and simulated pair distribution function.

Temperature-dependent total X-ray scattering measurements for water confined in bioactive glass samples with 5.9 nm pore diameter have been performed. Based on these experimental data, simulations were carried out using the Empirical Potential Structure Refinement (EPSR) code, in order to study the structural organization of the confined water in detail.

Unprecedented Reverse Volume Expansion in Spin-Transition Crystals.

The current craze for research around the spin crossover phenomenon can be justified to some extent by the mechanical properties due to the decrease of volume associated with the transition of the metal ion from the HS state to the LS state. As demonstrated here, the molecular complex [Fe(PM-pBrA) (NCS) ] exhibits, on the contrary, an increase of the unit-cell volume from HS to LS. This counter-intuitive and unprecedented behavior that concerns both the thermal and the photoexcited spin conversions is revealed by a combination of single-crystal and powder X-ray diffraction complemented by magnetic measurements.

Crystal structure of a new phen-yl(morpholino)methane-thione derivative: 4-[(morpholin-4-yl)carbothioyl]benzoic acid.

4-[(Morpholin-4-yl)carbothioyl]benzoic acid, CHNOS, a novel phen-yl(morpholino)methane-thione derivative, crystallizes in the monoclinic space group 2/. The morpholine ring adopts a chair conformation and the carb-oxy-lic acid group is bent out slightly from the benzene ring mean plane. The mol-ecular geometry of the carb-oxy-lic group is characterized by similar C-O bond lengths [1.

Photoinduced Mo-CN Bond Breakage in Octacyanomolybdate Leading to Spin Triplet Trapping.

The photoinduced properties of the octacoordinated complex K Mo (CN) ⋅2 H O were studied by theoretical calculations, crystallography, and optical and magnetic measurements. The crystal structure recorded at 10 K after blue light irradiation reveals an heptacoordinated Mo(CN) species originating from the light-induced cleavage of one Mo-CN bond, concomitant with the photoinduced formation of a paramagnetic signal. When this complex is heated to 70 K, it returns to its original diamagnetic ground state, demonstrating full reversibility.

Nonlinear optical organic-inorganic crystals: synthesis, structural analysis and verification of harmonic generation in tri-(o-chloroanilinium nitrate).

The structural and nonlinear optical properties of a new anilinium hybrid crystal of chemical formula (CHNCl·NO) have been investigated. The crystal structure was determined from single-crystal X-ray diffraction measurements performed at a temperature of 100 K which show that the compound crystallizes in a noncentrosymmetric space group (Pna2). The structural analysis was coupled with Hirshfeld surface analysis to evaluate the contribution of the different intermolecular interactions to the formation of supramolecular assemblies in the solid state that exhibit nonlinear optical features.

Very Long-Lived Photogenerated High-Spin Phase of a Multistable Spin-Crossover Molecular Material.

The spin-crossover compound [Fe( n-Bu-im)(tren)](PF) shows an unusual long relaxation time of 20 h after light-induced excited spin state trapping when irradiating at 80 K. This is more than 40 times longer than when irradiating at 10 K. Optical absorption spectroscopy, magnetometry, and X-ray diffraction using synchrotron radiation were used to characterize and explain the different relaxation behaviors of this compound after irradiation below and above 70 K.

Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-Polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks.

The mixed-valence FeFe 2D coordination polymer formulated as [TAG][FeFe(ClCNAn)]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn = 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 [FeFe(ClCNAn)] establish in the ab plane, with an intralayer metal-metal distance of 7.860 Å, alternating with cationic layers of TAG.

In-house time-resolved photocrystallography on the millisecond timescale using a gated X-ray hybrid pixel area detector.

With the remarkable progress of accelerator-based X-ray sources in terms of intensity and brightness, the investigation of structural dynamics from time-resolved X-ray diffraction methods is becoming widespread in chemistry, biochemistry and materials science applications. Diffraction patterns can now be measured down to the femtosecond time-scale using X-ray free electron lasers or table-top laser plasma X-ray sources. On the other hand, the recent developments in photon counting X-ray area detectors offer new opportunities for time-resolved crystallography.

Elastic Frustration Triggering Photoinduced Hidden Hysteresis and Multistability in a Two-Dimensional Photoswitchable Hofmann-Like Spin-Crossover Metal-Organic Framework.

We report a two-dimensional Hofmann-like spin-crossover (SCO) material, [Fe(trz-py){Pt(CN)}]·3HO, built from [FePt(CN)] layers separated by interdigitated 4-(2-pyridyl)-1,2,4,4H-triazole (trz-py) ligands with two symmetrically inequivalent Fe sites. This compound exhibits an incomplete first-order spin transition at 153 K between fully high-spin (HS-HS) and intermediate high-spin low-spin (HS-LS) ordered states. At low temperature, it undergoes a bidirectional photoswitching to HS-HS and fully low-spin (LS-LS) states with green and near-IR light irradiation, respectively, with associated T(LIESST = Light-Induced Excited Spin-State Trapping) and T(reverse-LIESST) values of 52 and 85 K, respectively.

Characterization of multifunctional β-NaEuF4/NaGdF4 core-shell nanoparticles with narrow size distribution.

The properties of β-NaEuF4/NaGdF4 core-shell nanocrystals have been thoroughly investigated. Nanoparticles with narrow size distribution and an overall diameter of ∼22 nm have been produced with either small β-NaEuF4 cores (∼3 nm diameter) or large β-NaEuF4 cores (∼18 nm diameter). The structural properties and core-shell formation are investigated by X-ray diffraction, transmission electron microscopy and electron paramagnetic resonance, respectively.

Photocrystallography and IR spectroscopy of light-induced linkage NO isomers in [RuBr(NO)2(PCyp3)2]BF4.

One single photo-induced linkage NO isomer (PLI) is detected and characterized in the dinitrosyl pentacoordinated compound [RuBr(NO)2(PCyp3)2]BF4 by a combination of photocrystallographic and IR analysis. In the ground state, the molecule adopts a trigonal-bipyramidal structure with the two NO ligands almost linear with angles Ru-N1-O1 = 168.92 (16), Ru-N2-O2 = 166.

Multiple light-induced NO linkage isomers in the dinitrosyl complex [RuCl(NO)2(PPh3)2]BF4 unravelled by photocrystallographic and IR analysis.

Multiple light-induced reversible metastable NO linkage isomers (PLIs) have been detected in the dinitrosyl compound [RuCl(NO)2(PPh3)2]BF4 by a combination of photocrystallographic and IR analysis. The IR signature of three PLI states has been clearly identified, with estimated populations of 59% (PLI-1), 8% (PLI-2) and 5% (PLI-3) for a total population of the metastable state of 72%. The structural configuration of the major component (PLI-1) has been derived by X-ray photocrystallography.

A comparative study of two polymorphs of L-aspartic acid hydrochloride.

Two polymorphs of L-aspartic acid hydrochloride, C4H8NO4(+)·Cl(-), were obtained from the same aqueous solution. Their crystal structures have been determined from single-crystal data collected at 100 K. The crystal structures revealed three- and two-dimensional hydrogen-bonding networks for the triclinic and orthorhombic polymorphs, respectively.

The structural properties of a noncentrosymmetric polymorph of 4-aminobenzoic acid.

The crystal structure of a polymorph of 4-aminobenzoic acid (PABA), C7H7NO2, at 100 K is noncentrosymmetric, as opposed to centrosymmetric in the structures of the other known polymorphs. The two crystallographically independent PABA molecules form pseudocentrosymmetric O-H..

Structural reinvestigation of the photoluminescent complex [NdCl2(H2O)6]Cl.

The structure of the photoluminescent compound hexaaquadichloridoneodymium(III) chloride has been redetermined from single-crystal X-ray diffraction data at 100 K, with the aim of providing an accurate structural model for the bulk crystalline material. The crystal structure may be described as a network of [NdCl2(H2O)6](+) cations with distorted square-antiprism geometry around the Nd(III) centre. The Nd(III) cation and the nonbonded Cl(-) anion are both located on twofold symmetry axes.

Light-induced bistability in the 2 D coordination network {[Fe(bbtr)3][BF4]2}∞ : wavelength-selective addressing of molecular spin states.

Whereas the neat polymeric Fe(II) compound {[Fe(bbtr)3 ][ClO4 ]2 }∞ (bbtr=1,4-di(1,2,3-triazol-1-yl)butane) shows an abrupt spin transition centered at 107 K facilitated by a crystallographic symmetry breaking, in the covalently linked 2D coordination network of {[Fe(bbtr)3 ][BF4 ]2 }∞ , Fe(II) stays in the high-spin state down to 10 K. However, strong cooperative effects of elastic origin result in reversible, persistent, and wavelength-selective photoswitching between the low-spin and high-spin manifolds. This compound thus shows true light-induced bistability below 100 K.

Giant Ising-type magnetic anisotropy in trigonal bipyramidal Ni(II) complexes: experiment and theory.

This paper reports the experimental and theoretical investigations of two trigonal bipyramidal Ni(II) complexes, [Ni(Me(6)tren)Cl](ClO(4)) (1) and [Ni(Me(6)tren)Br](Br) (2). High-field, high-frequency electron paramagnetic resonance spectroscopy performed on a single crystal of 1 shows a giant uniaxial magnetic anisotropy with an experimental D(expt) value (energy difference between the M(s) = ± 1 and M(s) = 0 components of the ground spin state S = 1) estimated to be between -120 and -180 cm(-1). The theoretical study shows that, for an ideally trigonal Ni(II) complex, the orbital degeneracy leads to a first-order spin-orbit coupling that results in a splitting of the M(s) = ± 1 and M(s) = 0 components of approximately -600 cm(-1).

Can a formally zwitterionic rhodium(I) complex emulate the charge density of a cationic rhodium(I) complex? A combined synchrotron X-ray and theoretical charge-density study.

The molecular electron densities of structurally related cationic ([(κ(2)-3-P(i)Pr(2)-2-NMe(2)-indene)Rh(COD)](CF(3)SO(3)), [1c](CF(3)SO(3))) and formally zwitterionic ([(κ(2)-3-P(i)Pr(2)-2-NMe(2)-indenide)Rh(COD)], 1z) complexes were accurately determined using synchrotron bright-source X-ray radiation at 30 K followed by multipolar refinement (COD = η(4)-1,5-cyclooctadiene). The densities were also obtained from density functional theory calculations with a large, locally dense basis set. A 28-electron ([Ar]3d(10)) core of the Rh atom was modeled by an effective core potential to obtain a density that was then augmented with relativistic cores according to the Keith-Frisch approximation.

Properties of metastable linkage NO isomers in Na2[Fe(CN)5NO]·2H2O incorporated in mesopores of silica xerogels.

We study the properties of photoinduced metal-nitrosyl linkage isomers in sodium nitroprusside (SNP) as a function of particle size. By embedding the molecular complex at various concentrations into mesopores of silica xerogels the size of the particles can be adjusted. The ground state is characterized by X-ray diffraction, absorption and infrared spectroscopy.

1-[3-(4-Nitro-phen-yl)propano-yl]urea acetic acid monosolvate.

The title compound, C(10)H(11)N(3)O(4)·C(2)H(4)O(2), was prepared by an electrochemical technique. In the crystal, acetic acid mol-ecules are involved in hydrogen bonding to two separate propano-ylurea mol-ecules, acting as a donor in an O-H⋯O inter-action and as an acceptor in two N-H⋯O inter-actions. The propano-ylurea mol-ecules inter-act with each other via N-H⋯O hydrogen bonds.

Cyanocarbanion-based spin-crossover materials: photocrystallographic and photomagnetic studies of a new iron(II) neutral chain.

A new iron(II) chain of formula [Fe(abpt)(2)(tcpd)] [1; (tcpd)(2-) = [C(10)N(6)](2-) = (C[C(CN)(2)](3))(2-) = 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide anion, abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole] has been synthesized and characterized by IR spectroscopy, detailed variable-temperature single-crystal X-ray diffraction, magnetic and photomagnetic measurements. The crystal structure determination of 1 reveals a one-dimensional structural architecture in which the (tcpd)(2-) cyanocarbanion acts as a μ(2)-bridging ligand and the two abpt molecules act as chelating ligands. Detailed X-ray diffraction studies as a function of the temperature (293-10 K) showed a strong modification of the iron coordination sphere, whose characteristics are in agreement with the presence of a spin-crossover transition from high spin (HS) to low spin (LS) in 1.