Microwave Assisted Crystal Growth of a New Organic—Decavanadate Assembly: [V10O27(OH)] · 2(C6N2H14) · (C6N2H13) · (C6N2H12) · 2H2O

Substitutional/positional disorder of biguanide and guanylurea in the structure of a decavanadate complex [(Bg)(HV10O285-)]0.4[(HGU+)(V10O286-)]0.6(H2Met2+)2(H3O+)·8H2O

A hydrated salt of decavanadate containing diprotonated metforminium(2+) (H2Met2+), hydronium (H3O+) and either neutral biguanide (Bg) or monoprotonated guanylurea (HGU+) exhibits a previously seen complex charge-stabilized hydrogen-bonded network [Chatkon et al. (2022). Acta Cryst. B78, 798-808]. Charge balance is achieved in two ways through substitutional disorder: a 0.6 occupied HGU+ cation is paired with a V10O286- anion, and a 0.4 occupied neutral Bg molecule is paired with a HV10O285- anion, with the remaining charge in both cases balanced by two H2Met2+ dications and one H3O+ monocation. Bg/HGU+ moieties exhibit bifurcated N-H...O hydrogen bonding to the H3O+ cation and are substitutionally/positionally disordered along with the H3O+ cation about an inversion center. The HGU+ V10O286- synthon seen in the previous study occurs again. Bg exhibits bifurcated hydrogen bonding from two amino groups to two rows of cluster O atoms running diagonally across the equatorial plane of the HV10O285- anion with a return hydrogen bond from the cluster H atom to the imino N atom of the Bg. Thus, a Bg...cluster synthon similar to the HGU+...cluster synthon previously reported is found. The disordered moieties occupy spaces with excess volume in the 3-D network structure. Interestingly, when the crystallographic unit cell of the current compound, whose X-ray data was collected at 100 K, is compared with that of a previous compound exhibiting the same supramolecular framework, unit-cell parameter c does not shorten as a and b expectantly do because of the lower data collection temperature. The lack of contraction on unit-cell parameter c is possibly due to the supramolecular structure.

Ab Initio Study of H-Bond Dynamics in Three-Component Crystals Comprising (DABCOH+ )n Polycationic Chains

In this work, the dynamic character of hydrogen-bond (H-bond) networks in two three-component crystals comprising polycationic chains was described. The first studied system was 1,4-diazabicyclo[2.2.2]octan-1-ium (DABCOH⁺ ) sulfamate monohydrate, known for its large negative linear compressibility. The second analyzed material was the newly obtained polar salt co-crystal: 1,4-diazabicyclo[2.2.2]octan-1-ium sulfamate urea. X-ray diffraction measurements enabled us to study the H-bond systems in both crystals using the graph set analysis. Obtained structures served as the initial models for Born-Oppenheimer molecular dynamics computations. A detailed study of intermolecular interactions and power spectra was conducted. The analysis of time and space correlations between the changes in H-bonds enabled the detection of proton transfer occurring in both systems at 300 K. Further study of those dynamic phenomena was done using the Energy Decomposition Analysis for selected trajectory fragments. Our work should improve the understanding of dielectric and ferroelectric properties of hybrid organic-inorganic materials.

Size and shape trump charge in interactions of oxovanadates with self-assembled interfaces: application of continuous shape measure analysis to the decavanadate anion

Using ⁵¹V NMR spectroscopy, dynamic light scattering and continuous shape analysis to characterize two polyoxometalate-encapsulation in reverse micelles.