Proton relay in a one-dimensional hydrogen-bonded chain composed of water molecules and a squaric acid derivative

Intermolecular Interactions in Functional Crystalline Materials: From Data to Knowledge

Intermolecular interactions of organic, inorganic, and organometallic compounds are the key to many composition–structure and structure–property networks. In this review, some of these relations and the tools developed by the Cambridge Crystallographic Data Center (CCDC) to analyze them and design solid forms with desired properties are described. The potential of studies supported by the Cambridge Structural Database (CSD)-Materials tools for investigation of dynamic processes in crystals, for analysis of biologically active, high energy, optical, (electro)conductive, and other functional crystalline materials, and for the prediction of novel solid forms (polymorphs, co-crystals, solvates) are discussed. Besides, some unusual applications, the potential for further development and limitations of the CCDC software are reported.

Effect of carbon-skeleton isomerism on the dielectric properties and proton conduction of organic cocrystal compounds assembled from 1,2,4,5-benzenetetracarboxylic acid and piperazine derivatives

Two isostructural 2D supramolecular cocrystal compounds show different dielectric responses and proton conductivities due to the alteration of the carbon-skeleton of piperazine derivatives.

Proton Order-Disorder Phenomena in a Hydrogen-Bonded Rhodium-η(5)-Semiquinone Complex: A Possible Dielectric Response Mechanism

A newly synthesized one-dimensional (1D) hydrogen-bonded (H-bonded) rhodium(II)-η(5)-semiquinone complex, [Cp*Rh(η(5)-p-HSQ-Me4)]PF6 ([1]PF6; Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; HSQ = semiquinone) exhibits a paraelectric-antiferroelectric second-order phase transition at 237.1 K. Neutron and X-ray crystal structure analyses reveal that the H-bonded proton is disordered over two sites in the room-temperature (RT) phase. The phase transition would arise from this proton disorder together with rotation or libration of the Cp* ring and PF6(-) ion. The relative permittivity εb' along the H-bonded chains reaches relatively high values (ca., 130) in the RT phase. The temperature dependence of (13)C CP/MAS NMR spectra demonstrates that the proton is dynamically disordered in the RT phase and that the proton exchange has already occurred in the low-temperature (LT) phase. Rate constants for the proton exchange are estimated to be 10(-4)-10(-6) s in the temperature range of 240-270 K. DFT calculations predict that the protonation/deprotonation of [1](+) leads to interesting hapticity changes of the semiquinone ligand accompanied by reduction/oxidation by the π-bonded rhodium fragment, producing the stable η(6)-hydroquinone complex, [Cp*Rh(3+)(η(6)-p-H2Q-Me4)](2+) ([2](2+)), and η(4)-benzoquinone complex, [Cp*Rh(+)(η(4)-p-BQ-Me4)] ([3]), respectively. Possible mechanisms leading to the dielectric response are discussed on the basis of the migration of the protonic solitons comprising of [2](2+) and [3], which would be generated in the H-bonded chain.

Reductive Cyclotetramerization of CO to Squarate by a U(III) Complex: The X-ray Crystal Structure of [(U (η-C8H6{SiiPr3-1,4}2)(η-C5Me4H)]2(μ-η2: η2-C4O4)

The U(III) mixed-sandwich compound [U(eta-C5Me4H)(eta-C8H6{SiiPr3-1,4}2)(THF)] 1 may be prepared by sequential reaction of UI3 with K[C5Me4H] in THF followed by K2[C8H6{SiiPr3-1,4}2]. 1 reacts with carbon monoxide at -30 degrees C and 1 bar pressure in toluene solution to afford the crystallographically characterized dimer [(U(eta-C8H6{SiiPr3-1,4}2)(eta-C5Me4H)]2(mu-eta2: eta2-C4O4) 2, which contains a bridging squarate unit derived from reductive cyclotetramerization of CO. DFT computational studies indicate that addition of a 4th molecule of CO to the model deltate complex [U(eta-COT)(eta-Cp)]2(mu-eta1: eta2-C3O3)] to form the squarate complex [U(eta-COT)(eta-Cp)]2(mu-eta2: eta2-C4O4)] is exothermic by 136 kJ mol-1.

Ferroelectric Metal−Organic Framework with a High Dielectric Constant

Hydrothermal reaction of (l)-N-(4'-cyanobenzy)-(S)-proline with CdCl2 as a Lewis acid catalyst and NaN3 gives colorless block compound 1, in which 1 displays a complicated 3D framework. Ferroelectric and dielectric property measurements reveal that 1 exhibits physical properties comparable to that of a typical ferroelectric compound with a dipole relaxation process and a dielectric constant of ca. 38.6 that makes it, by definition, a high dielectric material.

Structural relationship between a host included chain of spirocyclic water hexamers and bulk water – the role of water clusters in self assembly and crystallization processes

Infinite chains of spirocyclic water hexamers are included in the crystal lattice of a tin complex with a curved, hydrophobic surface and only weak intermolecular bonding interactions between the host molecules, so that the enclosed water clusters might be reminiscent of the solvation sphere in solution.

Discrete kink dynamics in hydrogen-bonded chains: the two-component model

We study discrete topological solitary waves (kinks and antikinks) in two nonlinear diatomic chain models that describe the collective dynamics of proton transfers in one-dimensional hydrogen-bonded networks. The essential ingredients of the models are (i) a realistic (anharmonic) ion-proton interaction in the hydrogen bond, (ii) a harmonic coupling between the protons in adjacent hydrogen bonds, and (iii) a harmonic coupling between the nearest-neighbor heavy ions (an isolated diatomic chain with the lowest acoustic band) or instead a harmonic on-site potential for the heavy ions (a diatomic chain subject to a substrate with two optical bands), both providing a bistability of the hydrogen-bonded proton. Exact two-component (kink and antikink) discrete solutions for these models are found numerically. We compare the soliton solutions and their properties in both the one- (when the heavy ions are fixed) and two-component models. The effect of stability switchings, discovered previously for a class of one-component kink-bearing models, is shown to exist in these two-component models as well. However, the presence of the second component, i.e., the softness of the heavy-ion sublattice, brings principal differences, like a significant difference in the stability switchings behavior for the kinks and the antikinks. Water-filled carbon nanotubes are briefly discussed as possible realistic systems, where topological discrete (anti)kink states might exist.

Proton Transfer and a Dielectric Phase Transition in the Molecular Conductor (HDABCO+)2(TCNQ)3

One-dimensional dielectric (N.H.N)( infinity ) hydrogen-bonding chains of monoprotonated 1,4-diazabicyclo[2.2.2]octane (HDABCO(+)) were introduced into an electrically conducting 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) salt as the countercation structure. Room-temperature electrical conductivity was approximately 10(-)(3) S cm(-)(1), with a semiconductive behavior. The temperature-dependent dielectric constants of (HDABCO(+))(2)(TCNQ)(3) indicated a dielectric transition at 306 K. A large deuterium isotope effect for the dielectric transition (DeltaT = 70 K) was observed for the deuterated salt, (DDABCO(+))(2)(TCNQ)(3). Thermally activated order/disorder of the protons or deuteriums within the one-dimensional hydrogen-bonding chains of (HDABCO(+))( infinity ) and (DDABCO(+))( infinity ) affected the dielectric responses in the TCNQ-based semiconductors.