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A series of mononuclear CuII complexes, [CuII(4-FBA)2(py)2(H2O)] (1), [CuII(3-FBA)2(py)2(H2O)] (2), and [CuII(3,4-F2BA)2(py)2(H2O)] (3), where 4-FBA = 4-fluorobenzoate, 3-FBA = 3-fluorobenzoate, 3,4-F2BA = 3,4-difluorobenzoate, and py = pyridine, respectively, was synthesized and the complexes crystallographically identified. All the CuII complex crystals share a one-dimensional O–H⋯O hydrogen-bonding chain substructure, although the mutual alignment of fluorinated benzoate (FxBA) ligands exhibits subtle differences among the various compounds, i.e., FxBA ligands align in an antiparallel fashion in crystals 1 and 3, while 3-FBA ligands in crystal 2 are interdigitated with a tilt along the a axis. Reversible phase transitions were found upon heating at 170.7, 171.3, and 267.5 K for crystals 1, 2, and 3, respectively; all crystals showed approximately 3% expansion and shrinkage of the intermolecular O–H⋯O hydrogen bond distances associated with the thermally activated orientational fluctuations of the FxBA ligands in crystals 1 and 3. The increase in dielectric constant with increasing temperature, at 240 K, activated molecular fluctuation in the 3,4-F2BA ligands in crystal 3. Heat capacity measurements indicated that both the expansion and shrinkage of hydrogen bonds, and the molecular fluctuation in 3,4-F2BA ligands, contributed to phase transition, and the latter caused dipole fluctuation, resulting in a dielectric anomaly in crystal 3. [ABSTRACT FROM AUTHOR]

Unexpected inversion‐symmetry breaking was observed in the order–disorder phase transitions of [M(acac)2(abco)2] (1; M=Co2+, 2; Ni2+, acac−=2,4‐pentanedionato, abco=1‐azabicyclo‐[2.2.2]‐octane=quinuclidine) during heating. The isostructural, transition‐free complexes [M(acac)2(cabco)2] (3; M=Co2+, 4; Ni2+, cabco=3‐chloro‐1‐azabicyclo‐[2.2.2]‐octane=3‐chloroquinuclidine) were also studied for comparison. Complexes 1 and 2 crystallized in ordered phases in the centrosymmetric I2/m space group at 100 K, whereas they crystallized in disordered phases in the non‐symmetric I2 space group at 300 K. The 60° step rotation disordering of the abco ligands was observed in the electron density maps of 1 and 2, which was consistent with the transition enthalpies estimated by differential scanning calorimetry (DSC). Gradual phase transitions were observed for 1 and 2 by DSC and powder X‐ray diffraction (PXRD) at approximately 225 K. The inversion‐symmetry disordering was likely induced by the local pseudo‐symmetry of the abco ligands, increasing from trigonal to hexagonal and the increased steric repulsion pathways among them. [ABSTRACT FROM AUTHOR]

Guanidinium (G+) and benzene-1,4-disulfonate (BDS2−) form a rigid electrostatic cation–anion crystal lattice, which undergoes an interesting dynamic structural reconstruction through guest adsorption–desorption processes with H2O, pyrrole (Pyrr), pyrazine (Pyz), thiophene (TP), pyridine (Py), 1,4-dioxane (Diox), or aniline (Ani). The host lattice of bis(guanidinium)benzene-1,4-disulfonate, (G+)2(BDS2−), which does not contain void spaces initially, changed to host–guest crystals of (G+)2(BDS2−)·(guest)x upon guest adsorption (x = 1, 2, and 3). The cation–anion electrostatic N–H+⋯−O3S– hydrogen bonds between the G+ cation and BDS2− dianion formed tightly bound two-dimensional (2D) structures. These layers are connected by perpendicular BDS2− dianions, forming the guest adsorption crystalline pores. The adsorption–desorption isotherm for Diox at 298 K indicated the formation of (G+)2(BDS2−)·(Diox)3, which was consistent with the single-crystal X-ray structural analysis. Single crystals of (G+)2(BDS2−)·(Py–H2O)2 consist of two hydrogen-bonded [(G+)2(BDS2−)]2 bilayers connected by the BDS2− dianions, forming crystalline pores that accommodate 2 Py guest molecules. The H2O molecules in (G+)2(BDS2−)·(Py–H2O)2 are lodged in the intralayer, leading to the [(G+)2(BDS2−)⋯(H2O)2⋯(G+)2(BDS2−)] hydrogen-bonded bilayer. The electrostatic cation–anion host lattice of (G+)2(BDS2−) responded to the guest adsorption–desorption cycle by a dynamic structural reconstruction. A guest adsorption of polar Ani into (G+)2(BDS2−) host changed the crystal symmetry from centric P1¯ to acentric P21 of (G+)2(BDS2−)·(Ani)3. [ABSTRACT FROM AUTHOR]

Co2+ magnetic cation was incorporated into (Ni(dmit)2)- pi-spin system.

A one-dimensional channel system x-Li(Pc), composed of π-radical Pc˙−, was investigated. Crystal structure analysis revealed that this channel surrounded by Li(Pc) columns is flexible, and gas adsorption/desorption measurements showed selective adsorption/desorption properties. Along with Li+ motion, specific dielectric properties induced by a guest species within the channel were also observed. [ABSTRACT FROM AUTHOR]

Many organic conducting materials are represented by the charge transfer (CT) complexes of tetrathiafulvalene (TTF) and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), which show high conductivity at room temperature. CT complexes of TTF and TCNQ each form columnar structures in crystals that enable the application of CT complexes in the formation of one-dimensional nanostructures such as nanowires and nanorods. Crown ethers units can also be used to support the preparation of self-assembled one-dimensional structures. In this study, we reported that the structures and electrical properties composed of TTF derivative (TTF-ER) and CT complexes composed of (TTF-ER)(TCNQ), (TTF-ER)(F2TCNQ) and (TTF-ER)(F4TCNQ). TTF-ER and the CT complexes organized one-dimensional structures on solid substrate, and in particular, TTF-ER formed high oriented nano-branched structures. In UV–vis and IR spectra, the CT complexes has conductivity similar to that of semiconductors, the electrical conductivities of (TTF-ER)(F2TCNQ) and (TTF-ER)(F4TCNQ) at room temperature were found to be 1.2 × 10−5 and 1.4 × 10−5 S cm−1, respectively. [ABSTRACT FROM AUTHOR]

A negative‐to‐positive transition of the temperature coefficients of thermal conductivity was found in the two‐dimensional organic–inorganic layered complex (C4H9NH3)2CuCl4 (C4CuCl4) over the three structural phase transitions in the range 176–218 K. The coefficients of the low‐temperature phases (85–200 K, α and β phases) were negative, as is typical for insulating crystals, whereas those of the high‐temperature phases (200–300 K, γ and δ phases) were positive, as is typical for glasses and liquids. Single‐crystal X‐ray structure analyses revealed that the tilted C4H9NH3+ chains in the α and β phases were fully outstretched in the δ phase, and the interlayer distances between the CuCl42− planes increased significantly. The γ phase was an intermediate phase that crystallized with an incommensurate structure, in which the CuCl42− sheets formed wave‐like structures consisting of connected alternating regions of β‐like and δ‐like moieties. In the γ and δ phases, thermal fluctuations of the C4H9NH3+ chains were found in the electron density maps; however, powder X‐ray diffraction (PXRD) data indicated that the thermal expansion of the C4H9NH3+ layers was restricted by the rigid CuCl42− layers. This situation was considered to induce glass‐like thermal conducting properties in the material, such as a positive temperature coefficient. The mean free path of the phonons estimated by using the thermal conductivities and heat capacities was a function of T−1 in the range 85–200 K, as would be expected for crystals, whereas it was approximately constant in the range 200–300 K, which is typical of glasses. In addition, the existence of soft vibration modes in the two‐dimensional perovskite CuCl42− sheets was revealed by analysis of the incommensurate crystal structure of the γ phase. These low‐energy vibration modes were believed to induce the cooperative phase transitions, along with the thermal fluctuations and van der Waals interactions in the C4H9NH3+ layers. [ABSTRACT FROM AUTHOR]