Structural Chemistry最新文献

With our previously developed method, we generated triply periodic surfaces (TPSs) including 131 minimal surfaces (TPMSs) using crystal structures of 923 metal-organic frameworks (MOFs) as templates. Our approach is based on the topological representation of a MOF structure as a periodic net with the subsequent construction of the natural tiling for the net and generation of TPSs/TPMSs from the faces of the tiles. The TPMSs were classified into nine topological types, three of which were previously unreported. The surfaces were optimized through smoothing and finite-thickness procedures and deposited in a database together with their topological descriptors. Being designed for practical applications, the surfaces are provided in formats compatible with additive manufacturing and standard software tools. Based on some TPMSs, we fabricated periodic porous samples and experimentally showed that they can possess better mechanical properties than the corresponding bulky material. This work expands the repertoire of known minimal surfaces and bridges the gap between micro- and macrostructures in materials design and fabrication. The relations between atomic crystalline architectures and materials with regular structure including metamaterials support the ideas of generalized crystallography disseminated by Alan Mackay long ago (Struct Chem 13:215–220, 2022).

This paper investigates several distinct attempts to generalize in higher dimension the standard 2-dimensional phyllotaxy set construction. We first recall known constructions for these sets on 2D manifolds of constant curvature (the Euclidean plane (mathbb {R}^2), the sphere (mathbb {S}^2) and the hyperbolic plane (mathbb {H}^2)). We then propose a first attempt to get a 3D phyllotactic set by piling up suitably shifted Euclidean 2D phyllotactic sets. A different, radially triggered, solution is then analyzed. An interesting phyllotactic set on the hypersphere (mathbb {S}^3) is then generated using a Hopf fibration approach. Finally, a simple 4-dimensional example is presented, generated as a simple product of two 2-dimensional planar sets. A 3D phyllotaxy candidate is then derived by applying a “Cut and Project” algorithm.

Selenites and hydroselenites exhibit a wide structural diversity and are considered as functional materials with a broad spectrum of potential physical properties. The complex crystal chemistry of these compounds is predominantly determined by the peculiarities of chemical bonds between SeO₃ triangles and other polyhedra, as well as the stereochemical activity of the lone electron pair, which makes this family similar in structure to sulfates and sulfites, as well as tellurites. The presence of stable modules in the structures of rare-earth selenites allows for the identification of modular series of crystal structures. This fact enables the classification of known structural types as well as the prediction of new ones using the formalism of modular crystal chemistry. This review highlights the breadth of research on the crystal structures of rare-earth selenites and aims to provide new insights for their more detailed analysis.

The structural mechanisms of the transitions VI–VII(VIII), IV → VIII, IV → VI, XII → VIII, XII → VI, and XII → Ic are studied. It is shown that the transitions between more dense crystal ices IV, VI, VII(VIII), and XII usually proceed by small shifts of molecules with rearrangement of more than a half of the initial hydrogen bonds. In this case, only finite fragments of the initial phase are retained, which consist of a few molecules. At the same time, as was shown previously, the transitions between less dense crystal ices can proceed by retaining all hydrogen bonds in large (i.e., infinite at least in one dimension) fragments of the initial structure, with a possible change of the bond lengths and angles inside these fragments and rearrangement of hydrogen bonds only between these fragments. In this case, a large fraction (more than a half) of the initial bonds is retained. The difference in the structural mechanisms of transitions between more dense ices or between less dense ices is related to the degree of space filling in the ice structures. The structural mechanisms of the transitions IV → Ic and XII → Ic are very close to those of the transitions IV → VIII and XII → VIII, respectively, because the structures of ices IV and XII are intermediate between those of ices Ic and VII(VIII).

A novel Cu(II) co-crystal compound, [Cu₂(μ-acetate-κ¹:κ¹-O,O’)₄(Isn)₂][Cu(acetate-κ¹-O)₂(Isn)₂(H₂O)]⋅5H₂O (1), (where Isn = isonicotinamide), was synthesized in ethanolic solution at room temperature. The compound was characterized by single-crystal X-ray diffraction, which revealed that it crystallizes in the monoclinic space group P2₁/c. The complex features two centrosymmetric paddle-wheel dicopper(II) moieties, a mononuclear unit, and five hydrogen-bonded water molecules. Both the lattice water molecules and the uncoordinated carboxylate oxygen atoms in the mononuclear moiety form a strong O–H⋯O hydrogen bonding network. Compound 1 represents a cocrystal structure formed by the incorporation of two chemically distinct copper complexes, one mononuclear and one dinuclear, into a single, ordered crystal lattice. Further analysis using FT − IR/FIR/Raman, NIR-Vis-UV spectroscopy, and computational methods, including Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) theory, was conducted to investigate intra- and intermolecular interactions. Two distinct complexes were identified in the unit cell: the mononuclear copper complex (M) and the dinuclear copper complex (D). Key intra-cell interactions were analyzed by examining two representative pairwise configurations: DD, consisting of two M units, and MD, formed by one M and one D unit. The interaction energies for DD and MD were − 27.3 kcal/mol and − 34.0 kcal/mol, respectively, after correcting for non-basis set superposition error (BSSE). The DD is stabilized by N–H···O hydrogen bonds, while the MD exhibits both π-π and hydrogen bond interactions, promoting enhanced stability and stacking along the b-axis. A frontier orbital gap of 2.6 eV suggests its potential for electronic, photonic, and sensing applications. Biological assays highlighted compound M’s significant antimicrobial activity, outperforming reference compounds like Cu(OAc)₂·H₂O and isonicotinamide against Candida albicans, MRSA, E. coli, and S. typhi. Molecular docking confirmed strong binding to C. albicans, with a binding energy of − 6.89 kcal/mol, whereas compound D showed moderate activity.

Graphical Abstract

This historical overview compiles over 30 years of structural research on f-element compounds initiated by Prof. Magdolna Hargittai and conducted first at the Hungarian Academy of Sciences (Budapest) with continuation later at the Joint Research Centre of the European Commission (Karlsruhe). The research tools included gas electron diffraction, gas-phase and matrix-isolation vibrational spectroscopy as well as quantum chemical calculations while the topic evaluated from small inorganic compounds up to large complexes of lanthanides and actinides.

Nowadays, the pipelines of drug candidates leading to new small-molecule drugs are fed by leads selected from large compound libraries produced by parallel and combinatorial synthetic methods. Tibetan monks long ago discovered how to improve the effectiveness of their prayers by operating prayer wheels in parallel. In traditional chemistry, however, new compounds were synthesized and screened individually. A new era began in the second half of the last century. Following a few attempts, two new methods spread which significantly increased the efficiency of chemical synthesis and screening of compounds: the parallel and combinatorial methods.

Various theories and hypotheses of crystal nucleation in different conditions and for different chemical substances are considered. Particular attention is paid to the crystallization of metals from melts and the influence of pressure on nucleation. It is shown that the understanding of nucleation processes is progressing, but the existence of a universal mechanism of nucleation for all substances and crystallization conditions is a distant prospect.