Особливості реалізації графічного конвеєру при візуалізації тривимірних моделей приміщень університету

В більшості систем комп‘ютерної графіки застосовується графічний конвеєр – логічна група послідовно виконуваних обчислень (етапів), які в результаті дають синтезовану сцену на екрані комп‘ютера. Серед основних – етапи геометричних перетворень та візуалізації. Результат виконання кожного з цих етапів впливає на кінцевий вигляд синтезованої сцени, тому їх коректне завершення є необхідною умовою отримання якісного зображення

Structural Studies on a New Family of Chiral BioMOFs

The use of a family of dinuclear copper­(II) complexes, prepared from enantiopure disubstituted oxamidato ligands derived from the natural amino acids l-alanine, l-valine, and l-leucine, as metalloligands toward barium­(II) cations leads to the formation of three novel three-dimensional (3D) chiral metal–organic frameworks (MOFs). They exhibit different architectures, which serve as playground to study both how the chiral information contained in the starting enantiopure ligands is ultimately transmitted to the 3D structure and the effect of the size of the aliphatic residue of the amino acid on the final architecture

Solvent-Dependent Self-Assembly of an Oxalato-Based Three-Dimensional Magnet Exhibiting a Novel Architecture

The old but evergreen family of bimetallic oxalates still offers innovative and interesting results. When (Me₄N)₃[Cr­(ox)₃]·3H₂O is reacted with Mn^II ions in a nonaqueous solvent, a novel three-dimensional magnet of the formula [N­(CH₃)₄]₆[Mn₃Cr₄(ox)₁₂]·6CH₃OH is obtained instead of the one-dimensional compound obtained in water. This new material exhibits an unprecedented stoichiometry with a binodal (3,4) net topology and the highest critical temperature (<i>T</i>_C = 7 K) observed so far in a manganese–chromium oxalate based magnet

Solvent-Dependent Self-Assembly of an Oxalato-Based Three-Dimensional Magnet Exhibiting a Novel Architecture

The old but evergreen family of bimetallic oxalates still offers innovative and interesting results. When (Me₄N)₃[Cr­(ox)₃]·3H₂O is reacted with Mn^II ions in a nonaqueous solvent, a novel three-dimensional magnet of the formula [N­(CH₃)₄]₆[Mn₃Cr₄(ox)₁₂]·6CH₃OH is obtained instead of the one-dimensional compound obtained in water. This new material exhibits an unprecedented stoichiometry with a binodal (3,4) net topology and the highest critical temperature (<i>T</i>_C = 7 K) observed so far in a manganese–chromium oxalate based magnet

Rational Synthesis of Chiral Metal–Organic Frameworks from Preformed Rodlike Secondary Building Units

The lack of rational design methodologies to obtain chiral rod-based MOFs is a current synthetic limitation that hampers further expansion of MOF chemistry. Here we report a metalloligand design strategy consisting of the use, for the first time, of preformed 1D rodlike SBUs (<b>1</b>) for the rational preparation of a chiral 3D MOF (<b>2</b>) exhibiting a rare <b>eta</b> net topology. The encoded chiral information on the enantiopure ligand is efficiently transmitted first to the preformed helical 1D building block and, in a second stage, to the resulting chiral 3D MOF. These results open new routes for the rational design of chiral rod-based MOFs, expanding the scope of these unique porous materials

Double Interpenetration in a Chiral Three-Dimensional Magnet with a (10,3)‑a Structure

A unique chiral three-dimensional magnet with an overall racemic double-interpenetrated (10,3)-a structure of the formula [(<i>S</i>)-(1-PhEt)­Me₃N]₄[Mn₄Cu₆(Et₂pma)₁₂]­(DMSO)₃]·3DMSO·5H₂O (<b>1</b>; Et₂pma = <i>N</i>-2,6-diethylphenyloxamate) has been synthesized by the self-assembly of a mononuclear copper­(II) complex acting as a metalloligand toward Mn^II ions in the presence of a chiral cationic auxiliary, constituting the first oxamato-based chiral coordination polymer exhibiting long-range magnetic ordering

New Magnetic Thin Film Hybrid Materials Built by the Incorporation of Octanickel(II)-oxamato Clusters Between Clay Mineral Platelets

We report on a new method based on the combination of Langmuir–Schaefer deposition with self-assembly to insert highly anisotropic Ni₈ molecules in a hybrid organic–inorganic nanostructure. Spectroscopic, crystallographic, and magnetic data prove the successful insertion of the guest cationic molecule between templating clay platelets. These results open a new route toward the highly controlled fabrication of tailored functional organic–inorganic nanomaterials

Selective Guest Inclusion in Oxalate-Based Iron(III) Magnetic Coordination Polymers

The preparation and structural characterization of four novel oxalate-based iron­(III) compounds of formulas {(MeNH₃)₂[Fe₂(ox)₂Cl₄]·2.5H₂O}_<i>n</i> (<b>1</b>), K­(MeNH₃)­[Fe­(ox)­Cl₃(H₂O)] (<b>2</b>), {MeNH₃[Fe₂(OH)­(ox)₂Cl₂]·2H₂O}_<i>n</i> (<b>3</b>), and {(H₃O)­(MeNH₃)­[Fe₂O­(ox)₂Cl₂]·3H₂O}_<i>n</i> (<b>4</b>) (MeNH₃⁺ = methylammonium cation and H₂ox = oxalic acid) are reported here. <b>1</b> is an anionic waving chain of oxalato-bridged iron­(III) ions with peripheral chloro ligands, the charge balance being ensured by methylammonium cations. <b>2</b> is a mononuclear complex with a bidentate oxalate, three terminal chloro ligands, and a coordinated water molecule achieving the six-coordination around each iron­(III) ion. Its negative charge is balanced by potassium­(I) and methylammonium cations. <b>3</b> and <b>4</b> are made up of oxalate-bridged and either hydroxo (<b>3</b>)- or oxo-bridged (<b>4</b>) iron­(III) chiral three-dimensional (3D) networks of formulas [Fe₂(OH)­(ox)₂Cl₂]_<i>n</i>^<i>n</i>− (<b>3</b>) and [Fe₂O­(ox)₂Cl₂]_<i>n</i>^2<i>n</i>− (<b>4</b>) with methylammonium (<b>3</b> and <b>4</b>) and hydronium (<b>4</b>) as counterions. The common point these compounds share is related to their synthetic strategy, which consists of the use of mixed alkaline/alkylammonium cations as templating agents for the growth of the 1D or 3D iron­(III) motifs. Interestingly, even in the presence of any given alkaline cation in the reaction solutions, the resulting coordination polymers (<b>1</b>, <b>3</b>, and <b>4</b>) exclusively contain the methylammonium cation, revealing the highly selective character of the 1D and 3D networks. Furthermore, the isolation of the very unstable compound <b>1</b> could be only achieved in the presence of the KCl salt, suggesting a probable templating effect of the potassium­(I) cations. Finally, a study of the variable-temperature magnetic properties of the 3D compounds <b>3</b> and <b>4</b> showed the occurrence of weak ferromagnetic ordering due to a spin canting, the value of the critical temperature (<i>T</i>_c) being as high as 70 K

Antisymmetric Exchange in Triangular Tricopper(II) Complexes: Correlation among Structural, Magnetic, and Electron Paramagnetic Resonance Parameters

Two new trinuclear copper­(II) complexes, [Cu₃(μ₃-OH)­(daat)­(Hdat)₂(ClO₄)₂(H₂O)₃]­(ClO₄)₂·2H₂O (<b>1</b>) and [Cu₃(μ₃-OH)­(aaat)₃(H₂O)₃]­(ClO₄)₂·3H₂O (<b>2</b>) (daat = 3,5-diacetylamino-1,2,4-triazolate, Hdat = 3,5-diamino-1,2,4-triazole, and aaat = 3-acetylamino-5-amino-1,2,4-triazolate), have been prepared from 1,2,4-triazole derivatives and structurally characterized by X-ray crystallography. The structures of <b>1</b> and <b>2</b> consist of cationic trinuclear copper­(II) complexes with a Cu₃OH core held by three <i>N</i>,<i>N</i>-triazole bridges between each pair of copper­(II) atoms. The copper atoms are five-coordinate with distorted square-pyramidal geometries. The magnetic properties of <b>1</b> and <b>2</b> and those of five other related 1,2,4-triazolato tricopper­(II) complexes with the same triangular structure (<b>3–7</b>) (whose crystal structures were already reported) have been investigated in the temperature range of 1.9–300 K. The formulas of <b>3–7</b> are [Cu₃(μ₃-OH)­(aaat)₃(H₂O)₃]­(NO₃)₂·H₂O (<b>3</b>), {[Cu₃(μ₃-OH)­(aat)₃(μ₃-SO₄)]·6H₂O}_<i>n</i> (<b>4</b>), and [Cu₃(μ₃-OH)­(aat)₃A­(H₂O)₂]­A·<i>x</i>H₂O [A = NO₃^– (<b>5</b>), CF₃SO₃^– (<b>6</b>), or ClO₄^– (<b>7</b>); <i>x</i> = 0 or 2] (aat =3-acetylamino-1,2,4-triazolate). The magnetic and electron paramagnetic resonance (EPR) data have been analyzed by using the following isotropic and antisymmetric exchange Hamiltonian: <i>H</i> = –<i>J</i>[<i>S</i>₁<i>S</i>₂ + <i>S</i>₂<i>S</i>₃] – <i>j</i>[<i>S</i>₁<i>S</i>₃] + <i>G</i>[<i>S</i>₁ × <i>S</i>₂ + <i>S</i>₂ × <i>S</i>₃ + <i>S</i>₁ × <i>S</i>₃]. <b>1</b>–<b>7</b> exhibit strong antiferromagnetic coupling (values for both –<i>J</i> and –<i>j</i> in the range of 210–142 cm^–1) and antisymmetric exchange (<i>G</i> varying from to 27 to 36 cm^–1). At low temperatures, their EPR spectra display high-field (<i>g</i> < 2.0) signals indicating that the triangles present symmetry lower than equilateral and that the antisymmetric exchange is operative. A magneto-structural study showing a lineal correlation between the Cu–O–Cu angle of the Cu₃OH core and the isotropic exchange parameters (<i>J</i> and <i>j</i>) has been conducted. Moreover, a model based on Moriya’s theory that allows the prediction of the occurrence of antisymmetric exchange in the tricopper­(II) triangles, via analysis of the overlap between the ground and excited states of the local Cu­(II) ions, has been proposed. In addition, analytical expressions for evaluating both the isotropic and antisymmetric exchange parameters from the experimental magnetic susceptibility data of triangular complexes with local spins (<i>S</i>) of ¹/₂, ³/₂, or ⁵/₂ have been purposely derived. Finally, the magnetic and EPR results of this work are discussed and compared with those of other tricopper­(II) triangles reported in the literature

High-Temperature Spin Crossover in a Mononuclear Six-Coordinate Cobalt(II) Complex

The six-coordinate cobalt­(II) complex of formula [Co­(tppz)₂]­(tcm)₂ exhibits a thermally induced spin-crossover behavior from a high spin (<i>S</i> = ³/₂) at higher temperatures to a low spin (<i>S</i> = ¹/₂) at lower temperatures, with the low-spin phase being achieved at <i>T</i> ≤ 200 K