Band 68, Heft 2

In this study, the effect of centrifugal force on the assembly and crystallization of binary colloidal mixtures is demonstrated. Monolithic pieces have been prepared which are characterized by a structural gradient along the direction of the centrifugal force. For a given number ratio of monodisperse 154 and 300 nm latex spheres, the absolute latex concentration was varied and with it the sedimentation velocity of the individual particle species. For three different concentrations it has been demonstrated that the structure of the binary colloidal assembly obtained after centrifugation is affected significantly. For the largest initial latex absolute concentrations, the structural variation along the packed latex column in the ultracentrifuge tube is minimal, while a decrease in the absolute concentrations leads to crystalline packing in defined regions of the column. The observation of the thermodynamically favored structure resembling NaCl, but also of the aluminum boride AlB 2 analog as well as unordered, glass-like packing depending on the mutual latex concentration under unchanged particle number and size ratio, shows that by centrifugation kinetically favored states can be realized. This result implies that centrifugation of binary latex mixtures is a promising route for investigating the self-organization of binary colloidal systems since the sedimentation velocities of the two particle species are different, and thus the local concentrations and mixing ratios vary continuously also enabling rare packing motifs. Graphical Abstract The Effect of Centrifugal Force on the Assembly and Crystallization of Binary Colloidal Systems: Towards Structural Gradients

The intermetallic calcium compounds CaTMg 2 and CaTCd 2 (T =Rh, Pd, Pt) were obtained by high-frequency melting of the elements in sealed niobium ampoules or through reactions in muffle furnaces. The polycrystalline samples were characterized by powder X-ray diffraction. They crystallize with a site occupancy variant of YPd 2 Si, a ternary ordered version of Fe 3 C. The structures of CaPdMg 2 and CaPdCd 2 were refined from single-crystal diffractometer data: Pnma, a=792.2(2), b=803.4(2), c=572.0(1) pm, wR 2 =0.0663, 1621 F 2 values, 24 variables for Ca 0:94 PdMg 2:06 and a=794.6(2), b=809.5(3), c=554.7(2) pm, wR 2 =0.0301, 819 F 2 values, 23 variables for CaPdCd 2 . A small range of homogeneity was observed for Ca 1-x PdMg 2+x . The magnesium and cadmium atoms build up three-dimensional tetrahedral substructures (306 - 327 pm Mg-Mg and 307 - 317 pm Cd-Cd) that resemble hexagonal diamond, lonsdaleite. Together with the palladium atoms one obtains three-dimensional, covalently bonded [PdMg 2 ] and [PdCd 2 ] networks which leave cages for the calcium atoms. The latter are bonded to these networks via shorter Ca-Pd contacts (298 - 319 pm in Ca 0:94 PdMg 2:06 and 295 - 312 pm in CaPdCd 2 ). The course of the interatomic distances is in line with calculated overlap populations. The CaPdMg 2 , SrPdMg 2 and CaRhIn 2 structures are all derived from a CaIn 2 -related subcell by an ordered filling of transition metal atoms into trigonal prisms. This leads to different herringbone patterns for the networks of puckered and elongated hexagons of magnesium and indium atoms. Graphical Abstract CaTMg 2 and CaTCd 2 (T =Rh, Pd, Pt) with YPd 2 Si-type Structure

A new lithium vanadium fluoride Li 2 VF 6 was prepared by reacting lithium fluoride LiF with vanadium tetrafluoride VF 4 in a monel capsule at 500 °C. The crystal structure has been determined by means of powder X-ray diffraction. Trirutile-type dilithium hexafluorovanadate(IV) crystallizes in the tetragonal space group P4 2 /mnm with lattice parameters a=459.99(1), b=459:99(1), c=896.64(2) pm. The presence of a Jahn-Teller effect is discussed. Graphical Abstract Preparation and Crystal Structure of a New Lithium Vanadium Fluoride Li 2 VF 6 with Trirutile-type Structure

A metal-organic framework based on 4-methylphthalic acid (H 2 L) and 4,4’-bipyridine (bpy), namely {[Cd(L)(bpy) 1:5 ]·2(H 2 O)} n (1), has been synthesized hydrothermally and characterized by IR spectroscopy, elemental analysis, thermogravimetry, and single-crystal X-ray crystallography. Complex 1 exhibits a 3D coordination network based on layers. Each layer consists of left- or right-handed {Cd-L-Cd-bpy-Cd-L-Cd-bpy} n double helices.Water molecules are also incorporated in the network. Compound 1 shows fluorescence at ca. 360 nm upon excitation at 304 nm. Graphical Abstract Hydrothermal Synthesis, Crystal Structure and Properties of a Novel 3D Metal-Organic Cd(II) Coordination Polymer Based on Helical Units

Three new lanthanide thioantimonates(V) [Ln(en)(teta)(SbS 4 )] {Ln=Sm (1), Eu (2), Gd (3); en=ethylenediamine; teta=triethylenetetramine} have been solvothermally synthesized and structurally characterized. Compounds 1 - 3 are isostructural. The [SbS 4 ] 3- anion acting as bichelating ligand is bound to the [Ln(en)(teta)] 3+ ion, resulting in a neutral complex [Ln(en)(teta)(SbS 4 )]. The central Ln 3+ ion lies within an eight-coordinate environment forming a distorted bicapped trigonal prism LnN 6 S 2 . Although a few lanthanide thioantimonates have been reported to date, they only contain one type of ethylene polyamine. Compounds 1 - 3 are rare examples of lanthanide thioantimonates with mixed ethylene polyamine ligands. The absorption edges of 1:75 eV for 1 and 2:27 eV for 3 have been derived from optical absorption spectra. Graphical Abstract Solvothermal Syntheses and Characterization of Three Lanthanide Thioantimonates(V) with Mixed Ethylene Polyamines

Two new copper(II) complexes, [Cu 2 (3-bpfp)(2,6-PDA) 2 (H 2 O) 2 ] (1) and [Cu(4-bpfp) 0:5 (glu)]·H 2 O (2), have been hydrothermally synthesized by self-assembly of isomeric bis(pyridylformyl)piperazine ligands [3-bpfp=bis(3-pyridylformyl)piperazine, 4-bpfp=bis(4- pyridylformyl)piperazine], rigid pyridine-2,6-dicarboxylic acid (2,6-H 2 PDA) or flexible glutaric acid (H 2 glu), and copper(II) chloride. Single-crystal X-ray diffraction analysis reveals that two adjacent Cu II ions are connected by the 3-bpfp ligand to build a dinuclear unit in complex 1, in which 2,6-PDA serves as a terminal chelating ligand. Adjacent dinuclear units are further linked by hydrogen bonding and π-π stacking interactions to form a three-dimensional (3D) supramolecular network. Complex 2 is a 3D coordination polymeric framework based on a layer polymer [Cu(glu)] n and bridging 4-bpfp ligands with 6-connected (4 4 .6 10 .8) topology. In 1 and 2, the ligands 3-bpfp and 4-bpfp adopt a μ 2 -bridging coordination mode (via ligation of pyridyl nitrogen atoms). The thermal stability and the electrochemical properties of the title complexes have been studied. Graphical Abstract Syntheses, Structures and Electrochemical Properties of Two New Copper(II) Complexes Based on Isomeric Bis(pyridylformyl)piperazine Ligands and Rigid=Flexible Organic Dicarboxylates

Cu(II) and Zn(II) salts react with 5-(1H-benzotriazol-1-ylmethyl)isophthalic acid (H 2 L) under hydrothermal conditions to yield two new complexes [Cu(L)(DMF)(H 2 O)] (1) and [Zn(L)] (2) [DMF=N,N-dimethylformamide], which have been characterized by single-crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. As a result, 1 shows a chain structure, further linked together by hydrogen bonding and π-π interactions to give rise to a 3D supramolecular framework. Complex 2 is a binodal (3,6)-connected 2D kgd network with (4 3 ) 2 (4 6 .6 6 .8 3 ) topology. The influential factors of synthetic strategies on coordination modes of the ligand and structures of the resulting complexes are embodied in the study. Significantly, 1 has structural features consistent with the Jahn-Teller effect. Furthermore, the fluorescence properties of 2 were preliminarily investigated. Graphical Abstract Cu(II) and Zn(II) Complexes with an N- and O-Donor Ligand: Structural Characterization, Jahn-Teller Effect and Fluorescence

A novel 2D coordination polymer, [Mn(pyphen)(L)] (1) (L=3-carboxy-1-(4'-(2''- carboxy)biphenylmethyl)-2-oxidopyridinium and pyphen=pyrazino[2,3- f ][1,10]phenanthroline), has been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, UV/Vis spectra and its optical band gap. Crystal data for 1: C 34 H 21 MnN 5 O 5 , monoclinic, space group P2 1/c , a=12.484(4), b=13.473(5), c=16.479(3) Å, b =99.618(6)° , V =2732.8(14) Å 3 , Z =4. In 1, each L ligand coordinates to three Mn(II) atoms through its two carboxylate groups and one phenolate unit. In this way, L 2- ligands link neighboring Mn(II) atoms to generate a layer structure. Graphical Abstract A Novel 2D Mn(II) Coordination Polymer Based on the New Flexible 3-Carboxy-1-(4'-(2''-carboxy)biphenylmethyl)-2-oxidopyridinium and the Pyrazino[2,3-f][1,10]phenanthroline Ligands

A cyanido-bridged Zn(II)-Ag(I) bimetallic coordination polymer, {[Zn(phen) 2 (H 2 O){Ag(CN) 2 }] [Ag(CN) 2 ]·MeOH} n (1), was prepared using ZnCl 2 , 1,10-phenanthroline (phen) and K[Ag(CN) 2 ] and characterized by IR spectroscopy, thermal analysis and X-ray crystallography. The crystal structure of 1 consists of dinuclear [Zn(phen) 2 (H 2 O){Ag(CN) 2 }] + cations, [Ag(CN) 2 ] - anions and a methanol molecule. The non-coordinated [Ag(CN) 2 ] - anions are linked to the [Zn(phen) 2 (H 2 O){Ag(CN) 2 }] + complex cations through argentophilic interactions leading to the formation of chains. The chains are connected by hydrogen bonds and π-π interactions to give a 3D network. Graphical Abstract A Zinc(II)-Silver(I) Bimetallic Coordination Polymer Assembled Through Argentophilic and π-π Interactions, f[Zn(phen) 2 (H 2 O) {Ag(CN) 2 g][Ag(CN) 2 ]·MeOH} n (phen=1,10-Phenanthroline)

Four new crystalline forms of piroxicam have been obtained and studied by single-crystal X-ray structure analysis. These comprise an addition salt with hydrochloric acid, acetic and isobutyric acids solvates, as well as piroxicam and furosemide cocrystal acetone solvate. All these new structures contribute to the variety of already known piroxicam crystalline forms. The analysis of conformations and tautomeric forms of piroxicam molecules in different crystal forms is presented. Graphical Abstract New Crystalline Forms of Piroxicam

An easy preparation of enaminonitrile derivatives and their transformation into new substituted azolopyrimidines is described. The one-step transformation was carried out under microwave irradiation and by classical heating methods. The use of microwave irradiation led to high conversion and shorter reaction times. Graphical Abstract Studies with Enamines: Route to Aminoazolopyrimidines and Arylazoazolopyrimidines

A one-pot synthesis of 5-aroyl-NH-1,3-oxazolidine-2-thiones by a regio- and chemoselective reaction of α-epoxyketones with thiourea or sodium thiocyanate in the presence of p-toluenesulfonic acid as catalyst in tetra-n-butylammonium chloride is described. Graphical Abstract Regio- and Chemoselective Synthesis of 5-Aroyl-NH-1,3-oxazolidine-2- thiones

Direct interaction of salicylaldehyde oxyanion with ethyl 7-chloro-8-nitro-4-oxoquinoline-3- carboxylate (2) delivered the respective 7-(2-formyl-phenoxy)-8-nitro-4-oxoquinoline-3-carboxylic ester 3. Reductive cyclization of 3 furnished the corresponding 4-oxo-[1,4]benzoxazepino[2,3- h]quinoline-3-carboxylic ester 5. Acid-catalyzed hydrolysis of the esters 3/5 produced the respective acids 4/6. Structural assignments for the new compounds 3 - 6 are supported by microanalytical and spectral (IR, HRMS, NMR) data and confirmed by X-ray structure determination for compound 5. Interestingly, compound 6 exhibited good antifungal activity against C. albicans. Graphical Abstract Heterocycles [h]-Fused onto 4-Oxoquinoline-3-carboxylic Acid. Part X [1]. Synthesis and X-Ray Structure of a Model 4- Oxo[1,4]benzoxazepino[2,3-h]quinoline-3-carboxylic Ester

2-Amino-7,7-dimethyl-5-oxo-1,4-diaryl-1,4,5,6,7,8-hexahydroquinoline-3-carbonitrile derivatives were synthesized by the one-pot four-component reaction of aromatic aldehydes, malononitrile, dimedone and arylamines in the presence of Zr(HPO 4 ) 2 ·H 2 O (α-ZrP) as an effective and recyclable solid acid catalyst, in high yields. Graphical Abstract Study of the Catalytic Activity of Zr(HPO 4 ) 2 in the Synthesis of Hexahydroquinoline Derivatives under Solvent-free Conditions

10-15 Fourteen ursolic acid derivatives, among them four novel compounds, were synthesized by modification either at the C-3, C-28 or both positions. The cytotoxic activity of the obtained derivatives was evaluated against the four human cancer cell lines KB (human mouth epidermal carcinoma), HepG2 (human hepatocellular carcinoma), MCF7 (human breast carcinoma) and Lu (human lung carcinoma). As the result, compounds 7and 8were from two to three times more active than ursolic acid on all four tested cell lines. This is the first report on cytotoxic effects of the synthetized ursolic acid derivatives 4, 8, and . Graphical Abstract Synthesis and Cytotoxic Activity of Ursolic Acid Derivatives