Volume 74, Issue 10

Two new compounds, namely, arteordosin A ( 1 ) and arteordosin B ( 2 ), were isolated from the CHCl 3 extract of Artemisia ordosica . This is the first report on the structure elucidation of arteordosin A ( 1 ) and arteordosin B ( 2 ) based on spectroscopic methods including electrospray ionization mass spectrometry, one-dimensional (1D) nuclear magnetic resonance spectroscopy (NMR) and 2D NMR techniques. Antioxidant activities of the compounds were measured for their radical scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl. Compound 1 (IC 50 of 1.01 mg mL −1 ) showed antioxidant activity similar to the standard reference ascorbic acid (IC 50 of 0.98 mg mL −1 ) and is more active than compound 2 (IC 50 of 1.87 mg mL −1 ). In conclusion, arteordosin A ( 1 ) and arteordosin B ( 2 ) may be used as potential antihyperlipidemic agent in routine clinical practice.

The phytochemical study of the roots, leaves and twigs of Penianthus camerounensis Dekker (Menispermaceae) has led to the isolation and the characterization of 20 compounds. A ceramide, camerounamide ( 1 ), and a furoclerodanediterpenoid, camerounin ( 2 ), have not been described previously, while the compounds xylopic acid ( 3 ), syringaresinol ( 4 ), iso -propylmethylcyclohexa-1,4-diol ( 5 ), 1-(28-hydroxyoctacosanoyl)glycerol ( 6 ), scoparone ( 7 ), friedelin ( 8 ), friedelanol ( 9 ) and betulinic acid ( 10 ) are being reported for the first time from the genus Penianthus alongside 10 known compounds ( 11–20 ). Chemical structures were determined using 1D- and 2D-NMR spectroscopy, MS and chemical analysis. Their chemotaxonomic importance is discussed.

By treatment of ethers of phenol, resorcinol, 2-napththol, alkylanisoles 10 , 13 , 15 , 17 , 20 , 22 , 24 , 28 with formic acid/borontrichloride the aromatic aldehydes 11 , 14 , 16 , 18 , 21 , 23 , 25, 26, 29 can generally be prepared in low yields. The formylation reactions proceed between −20 and −10°C within 20 min in 1,2-dichloroethane, chlorobenzene, or methylene chloride as solvents when formic acid and borontrichloride are used in excess [molar ratio of aromatic compound to HCOOH to BCl 3  = 1:1.2–1.7:1.6–1.8]. The more strongly activated 3,5-dimethoxyphenol ( 33 ) is formylated by formic acid/borontrichloride to give the aldehyde 34 with an acceptable yield. The reactions of resorcinol dimethylether with formic acid in the presence of super acids (mainly trifluormethansulfonic acid) in chlorobenzene or nitromethane deliver the aldehyde 21 only in small amounts.

A simple and rapid method for the preparation of benzopyranophenazines is presented, involving a one-pot four-component reaction of hydroxynaphthoquinone, o -phenylenediamine, benzaldehydes, and malononitrile with nano-Fe 3 O 4 @chitosan as an efficient heterogeneous solid acid catalyst under reflux conditions in ethanol. The catalyst is characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic susceptibility measurements, energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FT-IR) spectroscopy. Atom economy, high catalytic activity, a wide range of products, excellent yields in short reaction times, and low catalyst loading are some of the important features of this method.

The reactions of Zn(NO 3 ) 2  · 6H 2 O/CuCl 2  · 2H 2 O and 1,4-bis(1-imidazolyl)benzene (bib)/1,4-bis(1-imidazol-1-ylmethyl)benzene (biyb), carried out under hydrothermal conditions, produced two new coordination polymers [Zn(bib)(HCOO) 2  · H 2 O] ( 1 ) and [Cu(biyb)Cl 2 ] ( 2 ), respectively, which were characterized by elemental analysis, infrared spectroscopy, thermogravimetric analyses, and single-crystal X-ray diffraction. In complex 1 , the Zn II centers are bridged by bib ligands to form a chain, where the adjacent chains are condensed by strong intermolecular O–H · · · O hydrogen-bonding and aromatic π-π stacking interactions to generate a 3D supramolecular structure. In 2 , the Cu II centers are bridged by biyb ligands to form, again, chains through C–H · · · Cl hydrogen bonds, and these adjacent chains with different orientations are joined to generate a 3D supramolecular structure.

A heteroleptic silver(I) complex of bis(diphenylphosphano)methane (DPPM) and thiourea (tu) with the formula [Ag 2 (DPPM) 2 (tu) 3 ](NO 3 ) 2  · 2H 2 O ( 1 ) was prepared and characterized by infrared (IR) and nuclear magnetic resonance ( 1 H, 13 C, and 31 P) spectroscopic methods, and X-ray crystallography. The crystal structure determination has shown that the complex ( 1 ) is dinuclear having each silver(I) ion coordinated by two phosphorus atoms of DPPM molecules and two sulfur atoms of tu ligands adopting a distorted tetrahedral environment. The two silver atoms are bridged by one of the three tu molecules. The other two tu ligands are coordinated in a terminal mode; one with each silver(I) ion. The dinuclear units are associated to each other through hydrogen bonding interactions to form a three-dimensional network in the solid state. Complex 1 showed significant activity against two Gram-negative bacteria ( Escherichia coli, Pseudomonas aeruginosa ), and molds ( Aspergillus niger , Penicillium citrinum ), while the activities were poor towards yeasts ( Candida albicans , Saccharomyces cerevisiae ).

The new cluster compound [Nb 6 Cl 12 (HIm) 6 ](OAc) 2  · 3MeOH represents the first example of network compounds consisting of hexanuclear niobium cluster cations and acetate anions, which are connected though hydrogen bonds (besides Coulomb interactions). Hydrogen-bonded cation-anion pairs form chains, which are further extended to sheets by additional hydrogen bonds to co-crystallized methanol molecules. The synthesis of the title compound is based on a one-pot dehydration reaction of the cluster precursor [Nb 6 Cl 14 (H 2 O) 4 ] · 4H 2 O with acetic anhydride in the presence of imidazole at T  = 40°C.

The novel potassium nickel borate nitrate K 7 Ni[B 18 O 24 (OH) 9 ](NO 3 ) 6  ·(H 3 BO 3 ) was obtained from a simple hydrothermal synthesis in a stainless-steel autoclave at T  = 513 K starting with nickel dichloride hexahydrate, and boric and nitric acid with the pH adjusted to 8 by KOH. Single-crystal X-ray diffraction data provided the basis for the structure analysis and refinement. The compound crystallizes in the trigonal space group R 3̅ (no. 148) with the lattice parameters a  = 1222.29(8) and c  = 5478.4(4) pm. Generally, K 7 Ni[B 18 O 24 (OH) 9 ](NO 3 ) 6  ·(H 3 BO 3 ) is comprised of nitrate layers and complex nickel borate layers surrounded by boric acid, nitrate anions, and potassium cations.

Recently, Wang et al. (Z. Wang, J. Ha, Y. H. Kim, W. B. Im, J. McKittrick, S. P. Ong, Joule 2018 , 2 , 914–926) predicted and discovered Sr 2 LiAlO 4 , a quaternary compound with a layered structure crystallizing in the monoclinic space group P 2 1 / m , and they refined the structure from PXRD data. Upon partially substituting strontium with europium, the substance exhibits a yellow broadband luminescence consisting of two overlapping emission bands. In this paper, the crystal structure of Sr 2 LiAlO 4 is confirmed by additional SC-XRD measurements and a newly discovered polymorph of Sr 2 LiAlO 4 is presented crystallizing in the orthorhombic space group Cmcm . When Eu 2+ is incorporated, this polymorph exhibits only one of the emission bands present in the P 2 1 / m -polymorph. Additionally, two substitutional variants of Sr 2 LiAlO 4 are presented along with their luminescence properties upon incorporating Eu 2+ . One with a partial substitution of strontium for barium, leading to a structure in space group Pnma , and one with a partial substitution of oxygen for nitrogen, exhibiting the structure in space group Cmcm . The structure-property relationships in the above mentioned compounds are discussed with regard to their luminescence performance.

Bis(1,3,5-trimethylbenzene)gallium(I) tetra­chloridoaluminate(III), [(1,3,5-(CH 3 ) 3 C 6 H 3 ) 2 Ga][AlCl 4 ] ( 1 ), bis(1,3,5-trimethylbenzene)gallium(I) tetrabromido­aluminate(III), [(1,3,5-(CH 3 ) 3 C 6 H 3 ) 2 Ga][AlBr 4 ] ( 2 ) and (1,3,5-trimethylbenzene)gallium(I) tetraiodidoaluminate(III), [1,3,5-(CH 3 ) 3 C 6 H 3 Ga][AlI 4 ] ( 3 ) were synthesized from the corresponding subvalent Ga I /Al III mixed metal halides and characterized via C,H analysis, Raman spectroscopy, X-ray powder diffraction and X-ray single crystal diffraction. Compound 1 crystallizes in the noncentrosymmetric monoclinic space group Cc isotypic to [(1,3,5-(CH 3 ) 3 C 6 H 3 ) 2 Ga][GaCl 4 ]. For 2 and 3 the monoclinic space group P 2 1 / n is found, however, they are neither isotypic nor homotypic. While 2 is isotypic to [(1,3,5-(CH 3 ) 3 C 6 H 3 ) 2 In][InBr 4 ], 3 establishes a new structure type. In the solids of all three title compounds coordination polymeric chains are found, in 1 and 2 built up from bis(arene)-coordinated, in 3 from mono(arene)-coordinated Ga + ions and the corresponding Al X 4 − anions in a 1κCl:2κCl′ ( 1 ), 1κCl,Cl′:2κCl″ ( 2 ) or 1κCl,Cl′:2κCl″:3κCl‴ ( 3 ) bridging mode. Taking into account the weaker coordinating character of the AlCl 4 − as compared to the AlBr 4 − anion, in line with expectations the number of gallium halogen contacts is increased and the strength of the π -arene bonding is reduced in the bromide 2 as compared to the chloride 1 . Finally, with the even more strongly coordinating AlI 4 − anion the arene coordination is limited to one molecule. Considering mesitylene complexes of gallium, the formation of a mono(arene) complex is unprecedented and even considering group 13 elements in general, the formation of a mono(mesitylene) complex like 3 is unusual. Furthermore, compound 3 is the first structurally characterized arene solvate of a main group metal tetraiodidometallate.