Synthesis and antibacterial activity of some novel pyrazolopyridine derivatives

Eight pyrazolo[3,4-b]pyridine derivatives have been synthesized by Friedl?nder condensation of 5-aminopyrazole-4-carbaldehyde with active methylene compounds in basic medium. These compounds have been screened for their antibacterial activity against two Gram-negative and two Gram-positive bacterium. Pyrazolopyridines having the carboxamide group at the 5-position showed moderate to good activity against P. aeruginosa, E. coli, S. pneumoniae, and B. cereus.     

White-beam X-ray diffraction and radiography studies on high-boron-containing borosilicate glass at high pressures

ABSTRACT

Multi-angle energy-dispersive X-ray diffraction studies and white-beam X-ray radiography were conducted with a cylindrically shaped (1?mm diameter and 0.7?mm high) high-boron-content borosilicate glass sample (17.6% B₂O₃) to a pressure of 13.7?GPa using a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT of the Advanced Photon Source. The measured structure factor S(q) to large q?=?19 Å^?1 is used to determine information about the internuclear bond distances between various species of atoms within the glass sample. Sample pressure was determined with gold as a pressure standard. The sample height as measured by radiography showed an overall uniaxial compression of 22.5% at 13.7?GPa with 10.6% permanent compaction after decompression to ambient conditions. The reduced pair distribution function G(r) was extracted and Si–O, O–O and Si–Si bond distances were measured as a function of pressure. Raman spectroscopy of the pressure recovered sample as compared to starting material showed blue-shift and changes in intensity and widths of Raman bands associated with silicate and four-coordinated boron.     

X-Ray Analysis of N'-Acetyl-4-formyl-N'-phenylbenzohydrazide

Crystallography Reports - This communication is devoted to the X-ray diffraction study of a single crystal of the compound N '-acetyl-4-formyl-N '-phenylbenzohydrazide. The...     

Bivariate Entropy Analysis of Electrocardiographic RR–QT Time Series

QT interval variability (QTV) and heart rate variability (HRV) are both accepted biomarkers for cardiovascular events. QTV characterizes the variations in ventricular depolarization and repolarization. It is a predominant element of HRV. However, QTV is also believed to accept direct inputs from upstream control system. How QTV varies along with HRV is yet to be elucidated. We studied the dynamic relationship of QTV and HRV during different physiological conditions from resting, to cycling, and to recovering. We applied several entropy-based measures to examine their bivariate relationships, including cross sample entropy (XSampEn), cross fuzzy entropy (XFuzzyEn), cross conditional entropy (XCE), and joint distribution entropy (JDistEn). Results showed no statistically significant differences in XSampEn, XFuzzyEn, and XCE across different physiological states. Interestingly, JDistEn demonstrated significant decreases during cycling as compared with that during the resting state. Besides, JDistEn also showed a progressively recovering trend from cycling to the first 3 min during recovering, and further to the second 3 min during recovering. It appeared to be fully recovered to its level in the resting state during the second 3 min during the recovering phase. The results suggest that there is certain nonlinear temporal relationship between QTV and HRV, and that the JDistEn could help unravel this nuanced property.     

Synthesis,Characterization, and Crystal Structure of (E)-4-(2-(4-Cyanobenzylidene)hydrazinyl)benzonitrile Dimethyl Sulfoxide Hemisolvate

Crystallography Reports - (E)-4-(2-(4-Cyanobenzylidene)hydrazinyl)benzonitrile dimethyl sulfoxide hemisolvate, C15H10N4 ⋅ 0.5C2H6OS is synthesized following a green protocol and its crystal...     

Structural Features of <Emphasis Type="Italic">Ortho</Emphasis>-hydroxy Bis-phenols and Their Comparison with <Emphasis Type="Italic">Para</Emphasis>-hydroxy Bis-phenols

Abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions play a major role in the crystal packing of bis-phenols. The reaction of 2,4-dimethylphenol with aldehydes such as 2-naphthaldehyde, terephthaldehyde in the presence of trifluoracetic acid gave 2-[bis(2-hydroxy 3,5-dimethylphenyl)methyl]naphthalene (1) and 4-[bis(2-hydroxy 3,5-dimethylphenyl) methyl]benzaldehyde (2), respectively. The 2-[bis-(2-hydroxy 3,5-dimethylphenyl)-methyl]naphthalene (1) crystallizes in orthorhombic, Pbca, a = 11.905(3) ?, b = 18.788(5) ?, c = 18.894(5) ?, 4-[bis(2-hydroxy 3,5-dimethylphenyl)methyl] benzaldehyde (2) in monoclinic, Cc, a = 8.880(3) ?, b = 16.394(7) ?, c = 13.700(5) ?, γ = 104.542(2)°. The reaction of 2-nitrobenzaldehyde with 2,4-dimethylphenol gave 2-benzo[c] isoxazo-3-yl 4,6-dimethylphenol (3) and its crystal parameters are orthorhombic, P2₁2₁2₁, a = 7.737(6) ?, b = 11.885(9) ?, c = 13.336(8) ?. The reaction of 2,6-dimethylphenol with 4-nitrobenzaldehyde and 2-chlorobenzaldehyde gave bis(4-hydroxy 3,5-dimethylphenyl)(4-nitrophenyl)methane (4) and bis(4-hydroxy 3,5-dimethylphenyl)(2-chlorophenyl)methane (5), respectively. The bis(4-hydroxy 3,5dimethylphenyl)(4-nitrophenyl)methane (4) crystallizes in monoclinic, C2/c, a = 25.921(1) ?, b = 12.202(4) ?, c = 15.6084(7) ?, β = 122.172(4)°, and bis(4-hydroxy 3,5-dimethylphenyl) (2-chlorophenyl)methane crystallizes as acetonitrile solvate (5) in triclinic, P-1, a = 12.314(3) ?, b = 14.111(3) ?, c = 15.078(5) ?, α = 98.268(2)°, β = 111.268(2)°, γ = 114.304(1)˚. The unit cell of 5 contains two pairs of crystallographically unsymmetric molecules of bis-phenols. Index abstract The crystal structures of four bis-phenols are reported to substantiate the fact that the weak interactions plays a major role in crystal packing and can induce symmetry non-equivalence among bis-phenols in unit cell of bis-phenols.      

Symmetry-adapted linear combinations for the eigenvalues and eigenvectors of reciprocal graphs

ABSTRACT

Three classes of reciprocal graphs, viz. monocycle (G^C_n), linear chain (G^L_n) and star (G^K_n) with reciprocal pairs of eigenvalues (λ, 1/λ), are well known. Reciprocal graphs of monocycle (G^C_n) and linear chain (G^L_n) are obtained by putting a pendant vertex to each vertex of simple monocycle (C_n) and simple linear chain (L_n), respectively. A star graph of such kind is obtained by attaching a pendant vertex to the central vertex and to each of the (n ? 1) peripheral vertices of the star graph (K_{1, (n?1)}). An n-fold rotational axis of symmetry for G^C_n and (n ? 1)-fold rotational axis of symmetry for G^K_n have been exploited for obtaining their respective condensed graphs. The condensed graph for G^L_n has been generated from that of G^C_n incorporating proper boundary conditions. Condensed graphs are lower dimensional graphs and are capable of keeping all eigeninformation in condensed form. Thus the eigensolutions (i.e. the eigenvalues and the eigenvectors) in analytical forms for such graphs are obtained by solving 2 × 2 or 4 × 4 determinants that in turn result in the charge densities and bond orders of the corresponding molecules in analytical forms. Some mathematical properties of the eigenvalues of such graphs have also been explored.     

Coordination polymers and hydrogen‐bonded assemblies of 2,2′‐[2,5‐bis(carboxymethoxy)‐1,4‐phenylene]diacetic acid with ammonium,lanthanum and zinc cations

We report the synthesis of the 2,2′‐[2,5‐bis(carboxymethoxy)‐1,4‐phenylene]diacetic acid (TALH₄) ligand and the structures of its adducts with ammonium, namely diammonium 2,2′‐[2,5‐bis(carboxymethyl)‐1,4‐phenylenedioxy]diacetate, 2NH₄⁺·C₁₄H₁₂O₁₀²⁻, (I), lanthanum, namely poly[[aquabis[μ₄‐2,2′‐(2‐carboxylatomethyl‐5‐carboxymethyl‐1,4‐phenylenedioxy)diacetato]dilanthanum(III)] monohydrate], {[La₂(C₁₄H₁₁O₁₀)₂(H₂O)]·H₂O}_n, (II), and zinc cations, namely poly[[{μ₄‐2,2′‐[2,5‐bis(carboxymethyl)‐1,4‐phenylenedioxy]diacetato}zinc(II)] trihydrate], {[Zn(C₁₄H₁₂O₁₀)]·3H₂O}_n, (III), and poly[[diaqua(μ₂‐4,4′‐bipyridyl){μ₄‐2,2′‐[2,5‐bis(carboxymethyl)‐1,4‐phenylenedioxy]diacetato}dizinc(II)] dihydrate], {[Zn₂(C₁₄H₁₀O₁₀)(C₁₀H₈N₂)(H₂O)₂]·2H₂O}_n, (IV), the formation of all four being associated with deprotonation of TALH₄. Adduct (I) is a diammonium salt of TALH₂²⁻, with the ions located on centres of crystallographic inversion. Its crystal structure reveals a three‐dimensional hydrogen‐bonded assembly of the component species. Reaction of TALH₄ with lanthanum trinitrate hexahydrate yielded a two‐dimensional double‐layer coordination polymer, (II), in which the La^III cations are nine‐coordinate. With zinc dinitrate hexahydrate, TALH₄ forms 1:1 two‐dimensional coordination polymers, in which every Zn^II cation is linked to four neighbouring TALH₂²⁻ anions and each unit of the organic ligand is coordinated to four different tetrahedral Zn^II cation connectors. The crystal structure of this compound accommodates molecules of disordered water at the interface between adjacent polymeric layers to give (III), and it has been determined with low precision. Another polymer assembly, (IV), was obtained when zinc dinitrate hexahydrate was reacted with TALH₄ in the presence of an additional 4,4′‐bipyridyl ligand. In the crystal structure of (IV), the bipyridyl and TAL⁴⁻ entities are located on two different inversion centres. The ternary coordination polymers form layered arrays with corrugated surfaces, with the Zn^II cation connectors revealing a tetrahedral coordination environment. The two‐dimensional polymers in (II)–(IV) are interconnected with each other by hydrogen bonds involving the metal‐coordinated and noncoordinated molecules of water. TALH₄ is doubly deprotonated, TALH₂²⁻, in (I) and (III), triply deprotonated, viz. TALH³⁻, in (II), and quadruply deprotonated, viz. TAL⁴⁻, in (IV). This report provides the first structural characterization of TALH₄ (in deprotonated form) and its various supramolecular adducts. It also confirms the potential utility of this tetraacid ligand in the formulation of coordination polymers with metal cations.     

Artifacts in the electron paramagnetic resonance spectra of C60 fullerene ions: inevitable C120O impurity

Aspects of the electron paramagnetic resonance (EPR) spectra of C60n- fulleride ions (n = 2, 3) and the EPR signal observed in solid C60 are reinterpreted. Insufficient levels of reduction and the unrecognized presence of C120O, a ubiquitous and unavoidable impurity in air-exposed C60, have compromised most previously reported spectra of fullerides. Central narrow line width signals ("spikes") are ascribed to C120On- (n = odd). Signals arising from axial triplets (g approximately 2.0015, D = 26-29 G) in the spectrum of C602- are ascribed to C120On- (n = 2 or 4). Their D values are more realistic for C120O than C60. Less distinct signals from "powder" triplets (D approximately 11 G) are ascribed to aggregates of C120On- (n = odd) arising from freezing nonglassing solvents. In highly purified samples of C60, we find no evidence for a broad approximately 30 G signal previously assigned to a thermally accessible triplet of C60(2-). The C60(2-) ion is EPR-silent. Signals previously ascribed to a quartet state of the C60(3-) ion are ascribed to C120O4-. Uncomplicated, authentic spectra of C60- and C60(3-) become available when fully reduced samples are prepared under strictly anaerobic conditions from freshly HPLC-purified C60. Solid off-the-shelf C60 has an EPR signal (g approximately 2.0025, DeltaH(pp) approximately 1.5 G) that is commonly ascribed to the radical cation C60*+. This signal can be reproduced by exposing highly purified, EPR-silent C60 to oxygen in the dark. Doping C60 with an authentic C60*+ salt gives a signal with much greater line width (DeltaH(pp) = 6-8 G). It is suggested that the EPR signal in air-exposed samples of C60 arises from a peroxide-bridged diradical, *C60-O-O-C60* or its decomposition products rather than from C60*+. Solid-state C60 is more sensitive to oxygen than previously appreciated such that contamination with C120O is almost impossible to avoid.     

Pressure-induced amorphization in Y2(WO4)3: in situ X-ray diffraction and Raman studies

The high-pressure behavior of Y₂(WO₄)₃ has been investigated at room temperature by in situ X-ray diffraction and Raman scattering measurements. Both the studies show that beyond ∼3 GPa, this compound smoothly transforms from the ambient orthorhombic phase to a disordered phase. The structural modifications are found to be reversible up to ∼4 GPa but become irreversible at higher pressures. Low pressures of transformation imply that these changes are intrinsic and not due to non-hydrostatic stresses. In addition, the correlation between the stability range of orthorhombic phase and counter cation size supports that this compound has a large field of negative thermal expansion in this family of compounds.