A series of 12-phenyl-closo-thiaboranes (12-(4-X-C6H4)-closo-1-SB11H10, where X = OMe (2), X = SMe (3), X = Ph (4), and X = NMe2 (5)) has been prepared. Except for 2, all compounds exhibit a chalcogen bond of thiaborane to the phenyl ring or the neighboring molecule as major supramolecular structural motif. 5, having the strongest (-12.47 kcal/mol) structure-making intermolecular interaction via noncovalent S···π(phenyl) chalcogen bond, was crystallized from different solvents in the form of various solvatopolymorphs. n-Hexane and diethyl ether can be removed from 5 easily upon the formation of a porous material with large cavities (up to 20.5% of the unit cell). This first stable and useful noncovalently bound organic framework material with an ultramicroporous structure exhibits a molecular sieve effect. The selective and repeatable adsorption of CO2 to the material crystallized from n-hexane was explained on the basis of cooperative and consecutive machine-like molecular interactions of quadrupolar CO2 molecule with B-H and amino groups inside rectangular cavities.

• Publikační typ
• časopisecké články MeSH

Phthalocyanines and their building blocks, isoindoline-1,3-diimines (diiminoisoindoles, DIIs), represent a structurally diverse class of compounds with the ability to make metal complexes and perform in various fields from medicine to photovoltaics and homogeneous catalysis. According to the present study, monosubstituted diiminoisoindoles, their higher homologues, and complexes can be effectively prepared by addition of silylated lithium amides to 1,2-dicyanobenzene followed by mild protonolysis or a condensation. An addition of DII to carbodiimides or reactions of lithiated DIIs with acyl chlorides give DII-guanidines and amido derivatives. The imino group of the amido derivatives is preferentially and quantitatively reduced by sodium borohydride. Dynamic behavior and structure of all studied classes of compounds were investigated from the stereochemical point of view─possible E/Z-isomerization and dimerization (DIIs and amido derivatives), tautomerism (guanidines), and stability both in solution and in solid state. The resonance-assisted hydrogen bonds are present in all species except reduced amides, predetermining them to be exceptional ligands in coordination chemistry.

• Publikační typ
• časopisecké články MeSH

Although the binary alkali metal thallides ATl with A = Li, Na, K, and Cs have been reported in the literature, binary RbTl at ambient pressure is still missing. Experiments with a 1:1 ratio of Rb:Tl, either according to Zintl's procedure in low-temperature experiments in liquid ammonia or classical solid-state synthesis at high temperature, did not result in the desired product. Therefore, several ternary compositions with mixtures of K/Rb and Cs/Rb have been prepared. For K/Rb mixtures, a solid solution in the KTl structure type, up to a proportion of 69% rubidium, could be obtained. Site occupancy preferences for rubidium on the alkali metal sites in the KTl type are observed in experiments and supported by theoretical calculations. In contrast to Rb/K mixtures being realizable in the KTl structure type, Rb/Cs mixtures did not allow for the isolation of materials according to the CsTl structure type. Instead, two new monoclinic compounds could be isolated (Cs0.82Rb0.18Tl: C2/c, a = 14.4136(4) Å, b = 11.1678(3) Å, c = 40.8013(11) Å, β = 96.353(2)°, V = 6527.4(3) Å3; Cs0.58Rb0.42Tl: C2/c, a = 14.2610(3) Å, b = 11.1116(2) Å, c = 27.5589(7) Å, β = 104.056(2)°, V = 4236.30(17) Å3). Detailed DFT calculations on both binary and mixed cation systems were performed and support the experimental results.

• Publikační typ
• časopisecké články MeSH

The fascinating feature of metal-organic frameworks is that they can respond to external stimuli, unlike other inorganic materials. This feature corresponds to the framework's flexibility, which originates with the long-range crystalline order of the framework accompanied by cooperative structural transformability. We have synthesized a novel metal-organic framework comprised of Cu(I) nodes with pyrazine linkers and benzene-1,3,5-tricarboxylate acting as template anions, named CUCAM-1 [Cu(Py)2(BTC)]n. In the presence of polar solvent systems, CUCAM-1 undergoes an irreversible structural transformation to yield a mixed phase that consists of HKUST-1 [Cu3(BTC)2(H2O)3]n and another CUCAM-2 [Cu(Py)(BTC)]n MOFs, whose novel structure is successfully revealed by continuous rotation electron diffraction from the mixture. In this structural transformation, a new ligand exchange occurs where template anions become ligands, confirmed by single crystal X-ray analysis. Further, structural transformation and the mechanism are explained by ab initio molecular dynamics (AIMD) simulations. Interestingly, different halides (F-, Cl-, and Br-) can be accompanied to affect/control the composition of the second phase by favoring the formation of the HKUST-1 phase over CUCAM-2, which was evident by the powder X-ray diffraction studies. Furthermore, the structural transformation induced by I- resulted in a colorimetric response due to the formation of a new MOF CUCAM-3, paving the way for use as an iodide detector.

• Publikační typ
• časopisecké články MeSH

Electric fields represent an ideal means for controlling spins at the nanoscale and, more specifically, for manipulating protected degrees of freedom in multispin systems. Here we perform low-temperature magnetic far-IR spectroscopy on a molecular spin triangle (Fe3) and provide initial experimental evidence suggesting spin-electric transitions in polynuclear complexes. The co-presence of electric- and magnetic-dipole transitions, allows us to estimate the spin-electric coupling. Based on spin Hamiltonian simulations of the spectra, we identify the observed transitions and introduce the concept of a generalized exchange qubit. This applies to a wide class of molecular spin triangles, and includes the scalar chirality and the partial spin sum qubits as special cases.

• Publikační typ
• časopisecké články MeSH

Studying the self-assembly of chiral molecules in two dimensions offers insights into the fundamentals of crystallization. Using scanning tunneling microscopy, we examine an uncommon aggregation of polyaromatic chiral molecules on a silver surface. Dense packing is achieved through a chiral triangular tiling of triads, with N and N ± 1 molecules at the edges. The triangles feature a random distribution of mirror-isomers, with a significant excess of one isomer. Chirality at the domain boundaries causes a lateral shift, producing three distinct topological defects where six triangles converge. These defects partially contribute to the formation of supramolecular spirals. The observation of different equal-density arrangements suggests that entropy maximization must play a crucial role. Despite the potential for regular patterns, all observed tiling is aperiodic. Differences from previously reported aperiodic molecular assemblies, such as Penrose tiling, are discussed. Our findings demonstrate that two-dimensional molecular self-assembly can be governed by topological constraints, leading to aperiodic tiling induced by intermolecular forces.

• Publikační typ
• časopisecké články MeSH

Apremilast (APR) is an anti-inflammatory drug commonly used in the treatment of psoriasis. In efforts to enhance its solubility, several cocrystals with similar structural features have been developed. This study investigates the cocrystallization of APR with four phenolic-type coformers: phenol, catechol, pyrogallol, and hydroxyquinol. These coformers differ in the number and position of their hydroxyl groups, with their melting points varying by as much as 100 °C. Four novel cocrystal forms were synthesized, purified, and characterized using X-Ray diffraction and thermal analysis techniques. Surprisingly, the resulting cocrystals exhibited minimal differences in their melting points. The molecular packing of APR appears to limit the network-forming potential of the hydroxyl groups, a conclusion supported by the solved crystal structures, Hirshfeld surface analysis, and differential scanning calorimetry (DSC) results.

• Klíčová slova
• Apremilast, cocrystals, hydrogen bonds, phenolic compounds, π–π interactions,
• Publikační typ
• časopisecké články MeSH

Herein, we describe and investigate biological activity of three octahedral ruthenium(II) complexes of the type [Ru(C∧N)(phen)2]+, RuL1-RuL3, containing a π-expansive cyclometalating substituted benzo[g]quinoxaline ligand (C∧N ligand) (phen = 1,10-phenanthroline). Compounds RuL1-RuL3 in cervical, melanoma, and colon human cancer cells exhibit high phototoxicity after irradiation with light (particularly blue), with the phototoxicity index reaching 100 for the complex RuL2 in most sensitive HCT116 cells. RuL2 accumulates in the cellular membranes. If irradiated, it induces lipid peroxidation, likely connected with photoinduced ROS generation. Oxidative damage to the fatty acids leads to the attenuation of the membranes, the activation of caspase 3, and the triggering of the apoptotic pathway, thus implementing membrane-localized photodynamic therapy. RuL2 is the first photoactive ruthenium-based complex capable of killing the hardly treatable colon cancer stem cells, a highly resilient subpopulation within a heterogeneous tumor mass, responsible for tumor recurrence and the metastatic progression of cancer.

• MeSH
• apoptóza účinky léků   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• chinoxaliny * chemie   farmakologie   chemická syntéza   MeSH
• fotochemoterapie * MeSH
• fotosenzibilizující látky * farmakologie   chemie   chemická syntéza   terapeutické užití   MeSH
• komplexní sloučeniny * farmakologie   chemie   chemická syntéza   terapeutické užití   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádorové kmenové buňky * účinky léků   patologie   MeSH
• nádory tračníku * farmakoterapie   patologie   MeSH
• protinádorové látky * farmakologie   chemie   chemická syntéza   terapeutické užití   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• ruthenium * chemie   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chinoxaliny * MeSH
• fotosenzibilizující látky * MeSH
• komplexní sloučeniny * MeSH
• protinádorové látky * MeSH
• reaktivní formy kyslíku MeSH
• ruthenium * MeSH

Organic amines are found to be abundant in natural living systems. They also constitute an inestimable family of building blocks available in drug design. Considering the man-made cluster [(1,2-C2B9H11)2-3,3'-Co(III)]- ion (1-) and its application as an emerging unconventional pharmacophore, the availability of the corresponding amines has been limited and those with amino groups attached directly to carbon atoms have remained unknown. This paper describes the synthesis of compounds containing one or two primary amino groups attached to the carbon atoms of the cobaltacarborane cage that are accessible via the reduction of newly synthesized azides or via the Curtius rearrangement of the corresponding acyl azide. This substitution represents the first members of the series of azides and primary amines with functional groups bound directly to the carbon atoms of the cage. As expected, the absence of the linker along with the presence of the bulky anionic polyhedral ion leads to a significant alteration of the chemical and physicochemical properties. On a broader series of amines of the ion 1- we have thus observed significant differences in the acidity of the amino groups, depending on whether these are attached to the carbon or boron atoms of the cage, or the C-substituted amines contain an aliphatic linker of variable length. The compounds are relevant for potential use as cobalt bis(dicarbollide) structural blocks in medicinal chemistry and material science. Our study includes single-crystal X-ray diffraction (XRD) structures of both amines and a discussion of their stereochemical and structural features.

• Publikační typ
• časopisecké články MeSH

Differences/similarities of supramolecular motifs are discussed in two new thiophosphoramide structures and their Ni molecular complexes: (C2H5O)2P(S)(NHC(S)NHCH2C6H4X) and [{(C2H5O)2P(S)(NC(S)NHCH2C6H4X)}2Ni] (X = Cl/CH3I/II and III/IV). The structures have equal numbers of donor/acceptor sites contributing to classical hydrogen bonds (PS/CS and 2 × NH in ligands and 2 × PS and 2 × NH in the complexes). However, these donor and acceptor sites contribute to inter/intramolecular hydrogen bonding in ligands and intramolecular hydrogen bonding in complexes. In the supramolecular assemblies of the ligands, the classic hydrogen bonds (N-H⋯S[double bond, length as m-dash]C) are restricted in dimer synthons, and the weaker interactions (formed by Cl/CH3 substituents) compete against each other. In the complexes, despite the lack of classic intermolecular hydrogen bond, numerous weak interactions, e.g., C-H⋯Y (Y = S, O, Ni, N, and π), contribute to the molecular assemblies, which do not include the participation of Cl/CH3. Thus, different packing features of ligands, but similar in complexes are observed. Each ligand and the associated complex show nearly equal supramolecular motifs in the slice of the substituted benzyl groups, related to the formation of C-H⋯Cl/π⋯π for the 4-Cl-C6H4CH2 groups in I/III and C-H⋯π for the 4-CH3-C6H4CH2 groups in II/IV. The repeatabilities of the motifs made by 4-Cl-C6H4CH2/4-CH3-C6H4CH2 were checked by surveying 142/844 structures with 178/1482 segments in the CSD, which show that 17% and 12% of the structures exhibited similarities with the title structures. The methods X-ray crystallography, 2D fingerprint plots, electrostatic potential surfaces, QTAIM, and energy framework calculations were applied to present the discussion.

• Publikační typ
• časopisecké články MeSH