Volume 70, Issue 9

A new copper(II)/lead(II) complex [(terpy) 3 CuPb 5 Br 12 ] ( 1 ) (terpy = 2,2′:6′,2″-terpyridine) has been synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. The copper(II) and lead(II) ions in the title complex are in distorted six- (Cu(II), Pb(II)) and eight-fold (Pb(II)) coordination environments, in which the donor atoms are provided by bromide anions and nitrogen atoms of the 2,2′:6′,2″-terpyridine ligands. Complex 1 contains [(terpy) 4 Pb 9 Br 20 ] 2– building blocks. These bromoplumbate(II) clusters are connected by (terpy) 2 Cu 2 Br 4 units along the crystallographic b axis and by PbBr 6 units along the a axis, thereby forming an extended sheet structure.

A new dimeric naphtho- γ -pyrone, 2-hydroxydihydronigerone ( 1 ), along with five compounds, nigerone ( 2 ), pyrophen ( 3 ), kojic acid ( 4 ), 4-(hydroxymethyl)-5-hydroxy-2 H -pyran-2-one ( 5 ), and p -hydroxyphenylacetic acid ( 6 ), was isolated from an endophytic fungus Aspergillus niger AKRN associated with the roots of Entandrophragma congoënse . The structure of the new compound has been elucidated using spectroscopic data including 1D and 2D NMR as well as the high-resolution mass spectrometry. Compounds 1 – 5 showed weak antimicrobial activity on five selected Gram-negative bacteria, namely Enterobacter aerogenes (CM64), Enterobacter cloacae (BM67), Klebsiella pneumonia (K2), and Escherichia coli (ATCC8739 and ATCC10536).

Starting with 1 H - 3-phenyl-5-(pyridin-2-yl)-1,2,4-triazole (1-Hppt), a Co(III) complex, [Co(ppt) 3 ] ( 1 ), has been synthesized by reaction with CoF 3 under hydrothermal conditions and characterized by its infrared spectrum and elemental analysis. The structure was determined by single-crystal and powder X-ray diffraction. Density functional theory (DFT) was employed to determine the optimized geometry and preferred conformation of the free ligand. A supramolecular network is formed via π – π stacking interactions. The conformation and geometry of the ligands correspond with the calculated results.

The naturally occurring oxygenated bibenzyls lunularin and m- O -methyllunularin were prepared in a modular synthesis in four steps from two appropriate iodophenols and trimethylsilylacetylene utilizing microwave-assisted Sonogashira couplings as the crucial steps. The antimicrobial activity of the resulting natural products was evaluated in an agar diffusion assay.

The crystal structure of 4,4,4′,4′-tetramethyl-2,2′-bipyrrolidinyliden-3,3′-dione ( 3 ) („urindigo“ = primordial indigo) was determined by X-ray diffraction. The molecule has the trans -configuration as indigo itself. Within the parent group trans -(OC)(HN)C=C(CO)(NH) the distances and angles of 3 are very similar to that in indigo: C=C (136.6 pm), C–N (140.9 pm), C–C (145.6 pm), C=O (122.6 pm). The intramolecular N–H···O bonds in 3 and indigo are similar whereas the intermolecular hydrogen bonds in the former are substantially weaker. The latter observation finds its interesting parallel in the markedly smaller difference between the Vis absorptions of the gaseous and the solid primordial indigo in comparison to that of indigo. The present results support the early view by Lüttke and Klessinger that the trans -(OC)(HN)C=C(CO)(NH) fragment is the parent chromophor of indigo dyes.

The potassium pentaborate KB 5 O 7 (OH) 2 reported herein crystallizes in the monoclinic space group P 2 1 /c (no. 14) with the lattice parameters a = 904.8(2), b = 753.2(2), c = 1214.9(5) pm, β = 117.16(2)°, and V = 0.73663(5) nm 3 ( Z = 4). It is a disordered structural variant of an already known compound with the same composition ( a = 766.90(3), b = 904.45(3), c = 1223.04(4) pm, β = 119.132(2)°, and V = 0.74101(5) nm 3 ( Z = 4)) reported by Wu in 2011. The disorder of the potassium cation in the single crystal structure determination of KB 5 O 7 (OH) 2 presented here leads to a remarkably elongated a axis and a corresponding reduction of the length of the b axis in comparison to the ordered compound. The disordered variant was obtained through a hydrothermal synthesis from KNO 3 , B 2 O 3 , and Ce(NO 3 ) 3 ·6H 2 O with a molar ratio of 1:1:0.07.

Phytochemical investigation of the acetone extract of Macaranga javanica leaves afforded three new prenylated 9,10-dihydrophenanthrenes, macajavanicins A–C ( 1–3 ). Structures of these compounds were elucidated mainly by NMR and mass spectral data. Along with compounds 1–3 , two known prenylated dihydrostilenes, laevifolins A and B ( 4 , 5 ), were also isolated. The presence of these new 9,10-dihydrophentanthrene derivatives is the first time in the genus Macaranga , and its chemotaxonomic significances are briefly discussed. The antibacterial properties of compounds 1–5 against eight pathogenic bacteria are also described.

The isothermal section of the Tm–Ni–In system at T = 870 K was constructed. Nine ternary compounds: Tm 10 Ni 9 In 20 , TmNi 1–0.60 In 1–1.40 , Tm 2 Ni 2 In, Tm 2 Ni 1.78 In, Tm 5 Ni 2 In 4 , Tm 11 Ni 4 In 9 , Tm 4.83 Ni 2 In 1.17 , Tm 6 Ni 2 In and Tm 14 Ni 3 In 3 exist in the system at the temperature of investigation. Solid solutions with In/Ni and Tm/In mixing were noticed for numerous compounds. A broad substitution of Ni for In was observed for TmNi 1–0.60 In 1–1.40 , and of Tm for In for the TmNi 2 –TmNi 4 In section. An interstitial solid solution Tm x NiIn, based on binary equiatomic NiIn, extends up to 8 at.% Tm ( x = 0.17). The magnetic properties of TmNiIn, Tm 2 Ni 2 In and Tm 5 Ni 2 In 4 are also reviewed.

The iron arsenide Eu 3 Fe 2 O 5 Fe 2 As 2 was synthesized at 1173–1373 K in a resistance furnace and characterized by X-ray powder diffraction with Rietveld analysis: Sr 3 Fe 2 O 5 Cu 2 S 2 type, I 4/ mmm , a = 406.40(1) pm, c = 2646.9(1) pm. Layers of edge-sharing FeAs 4/4 tetrahedra are separated by perovskite-like oxide blocks. No structural transition occurs in the temperature range from 10 to 300 K. Magnetic measurements have revealed Curie–Weiss behavior with an effective magnetic moment of 7.79 μ B per europium atom in agreement with the theoretical value of 7.94 μ B for Eu 2+ . A drop in the magnetic susceptibility at 5 K indicates possible antiferromagnetic ordering. 151 Eu and 57 Fe Mössbauer spectroscopic measurements have confirmed a beginning cooperative magnetic phenomenon by showing significantly broadened spectra at 4.8 K compared to those at 78 K.

The synthesis of 17 novel conformationally constrained pyrazole derivatives is reported herein, along with the assessment of their anti-proliferative and anti-angiogenic activities. The evaluation of their inhibitory effect on cell proliferation against HepG2, HeLa, and MCF-7 cells revealed the pyrrolo[2,3- g ]indazole 23 as a potent inhibitor of cell growth with IC 50 values of 5 μ m . Additionally, the inhibition of vascular endothelial growth factor by pyrazoles 20 and 23 (30 % and 35 %, respectively) in HeLa supernatant cells was evidenced. These findings highlight the usefulness of these compounds as potential scaffolds for the design and development of novel anti-cancer agents with pronounced anti-angiogenic activity.

Further chemical investigation of the fruit of the mangrove Avicennia marina led to the isolation of a new caffeic acid derivative, maricaffeolylide A ( 1 ), and a new megastigmane derivative, maricyclohexene A ( 2 ). The structures of the isolates were elucidated on the basis of extensive spectroscopic analysis. The antioxidant activity of 1 and 2 was also evaluated using a cellular antioxidant activity assay, and catechol 1 showed antioxidant activity with an EC 50 value of 24 ± 0.3 μm.