Self-assembly of two- and three-dimensional coordination networks with hexamethylenetetramine and different silver(I) salts

Intermolecular Forces Driving Hexamethylenetetramine Co-Crystal Formation, a DFT and XRD Analysis

Interest in co-crystals formation has been constantly growing since their discovery, almost a century ago. Such success is due to the ability to tune the physical-chemical properties of the components in solid state by avoiding a change in their molecular structure. The properties influenced by the co-crystals formation range from an improvement of mechanical features and chemical stability to different solubility. In the scientific research area, the pharmacological field is undoubtedly one of those in which an expansion of the co-crystal knowledge can offer wide benefits. In this work, we described the crystalline structure of hexamethylenetetramine co-crystallized with the isophthalic acid, and we compared it with another co-crystal, showing the same components but different stoichiometry. To give a wider overview on the nature of the interactions behind the observed crystal packing and to rationalize the reasons of its formation, a computational analysis on such structures was carried out.

Varying the Dimensionality of Cu(II)-Based Coordination Polymers Through Solvent Influence

This work reports the synthesis and structure of a large porous zeotype network observed within compound (1) using {Cu2(piv)4} as the linking unit (piv = pivalate). The slow in situ formation of the hmt ligand (hexamethylenetetramine) appears to be key in generating a µ4-bridging mode of the hmt-node. Attempts to improve the low yield of compound (1) using different solvent layer diffusion methods resulted in the µ3-hmt complexes (2) and (3). Both compounds exhibit a 3D network of two intertwined chiral networks. Strong hydrogen bonding present in (3) leads to the formation of intertwined, DNA-like double-helix structures. The use of bulky solvents in the synthesis of compound (4) leads to the structure crystallizing solvent-free. The packing of (4) is dominated by energy minimization, which is achieved when the 1D-“cylinders” pack into the closest possible arrangement. This work highlights the potential for solvent controlled synthesis of extended copper-hmt systems.

Two-Dimensional versus Three-Dimensional Self-Assembly of a Series of 5-Alkoxyisophthalic Acids

Physisorbed self-assembled monolayers (SAMs) have been suggested as potential models for three-dimensional (3D) crystallization. This work studies the effect of altering the chain length of 5-alkoxyisophthalic acid (C _nISA) on self-assembled morphology in both two-dimensional (2D) and 3D to explore the extent comparisons can be drawn between dimensions. Previous studies of 5-alkoxyisophthalic acid at solid-liquid interfaces (2D) reported different morphologies for C₅ISA and C₆ISA-alkoxy chains on the one hand and C₁₀ISA and C₁₈ISA on the other. Independently, also in 3D a dependence of morphology on chain length has been reported, including an unexpected inclusion of a solvent in the 3D morphology of C₆ISA, while the previous reports of 2D self-assembly were driven only by molecule-molecule and molecule-substrate interactions. However, a complete set of data for comparison has been missing. Here, we report scanning tunneling microscopy (STM) and molecular dynamics simulations performed for C₂ISA self-assembled monolayers (SAMs) and STM imaging of C₆ISA-C₉ISA SAMs, to further examine self-assembly behavior in 2D. In 3D, X-ray diffraction analysis of C₂ISA single crystals was carried out to complete the data set. With a complete set of data, it was observed that regardless of the dimension, short-chain-length C _nISAs formed H-bonding-dominated structures, mid-chain-length C _nISAs exhibited solvent-dependent morphologies, and long-chain-length C _nISAs displayed van der Waals-dominated solvent-independent structures. However, the transition point among morphologies occurred at different chain lengths in 2D and 3D regardless of the dominant interaction. The results of this study inform the design of 2D films and guide the application of knowledge from physisorbed SAMs to 3D systems, including mixed-dimensional (2D/3D) van der Waals heterostructures.

Three Mn(ii) coordination polymers with a bispyridyl-based quinolinate ligand: the anion-controlled tunable structural and magnetic properties

Three anion-controlled Mn(ii) coordination polymers were assembled from a bispyridyl-based quinolinate ligand.

Two 2D sliver complexes with a symmetric and noncentrosymmetric architecture controlled by the metal–ligand ratio

By controlling the metal–ligand ratio, we obtained two 2D sliver complexes from a symmetric to noncentrosymmetric architecture based on 2,2′-phosphinico-dibenzoic acid (H₃L). The four groups around the phosphorus atom of the L³⁻ ligand connect the Ag(i) ions through different coordination modes to form a noncentrosymmetric complex 2.

Assembly of 1,2,3-benzenetricarboxylic acid and sliver(I) metal center to a novel 3D supramolecular framework: syntheses, structure and properties

The reaction of AgNO3, pyrazine (pyz) and 1,2,3-benzenetricarboxylic acid (H3btc) leads to a new 3D supramolecular architecture, namely {[Ag(H2btc)(pyz)]·(H2O)2}n (1), which has been characterized by IR spectroscopy, elemental analysis, thermogravimetry, photoluminescent and powder X-ray diffraction (PXRD). Compound 1 displays a 3D supramolecular network, which is built from cationic Ag-pyz chains and anionic [(H2btc)n·2H2O]- layers through the weak Ag⋯O interaction. Complex 1 exhibits photoluminesscence with an emission maximum at ca.391 nm upon excitation at ca. 241 nm.

High-nuclearity silver clusters templated by carbonates generated from atmospheric carbon dioxide fixation

Two high-nuclearity silver clusters have been prepared by reacting AgC(2)Bu(t) with AgBF(4) (or AgOTf) in the presence of TMEDA in air. The reaction takes up atmospheric CO(2) to give CO(3)(2-), which functions as a template for the formation of the cage compounds, whose nuclearities depend on the particular counteranions employed.