Antimicrobial Activity and DFT Studies of a Novel Set of Spiropyrrolidines Tethered with Thiochroman-4-one/Chroman-4-one Scaffolds

A novel series of 14 spiropyrrolidines bearing thiochroman-4-one/chroman-4-one, and oxindole/acenaphthylene-1,2-dione moieties were synthesized and characterized by spectroscopic techniques, as well as by three X-ray diffraction studies, corroborating the stereochemistry. Quantum chemical calculations studies, using the DFT approach, were performed to rationalize the stereochemical outcome. These N-heterocycles were evaluated for their antibacterial and antifungal activities against some pathogenic organisms. Several compounds displayed moderate to excellent activity towards the screened microbe strains in the study compared to Amoxicillin (AMX), Ampicillin (AMP), and Amphotericin B. Furthermore, a structural activity relationship (SAR) was established considering the synthesized compounds. Pharmacokinetic studies reveal that these derivatives exhibit an acceptable predictive ADMET profile (Absorption, Distribution, Metabolism, Excretion and Toxicity) and good drug-likeness.     

Polysulfonylamines. CXXXII.

The crystal structure of the title compound, C₅H₇N₂⁺·C₁₂H₁₀NO₄S₂⁻, consists of two independent cation–anion pairs, A and B. Within each pair, the H—N—C—N*—H grouping (N*—H is the pyridinium function) and one N—S—O moiety of the anion are linked by N*—H⃛N and N—H⃛O hydrogen bonds to form an antidromic ring motif of type R²₂(8). The remaining amino donors give rise to N—H⃛O hydrogen bonds, connecting the ion pairs into A–B–A–B– chains. The structure testifies to the persistence of the R²₂(8) motif in question, which was previously detected as a highly robust supramolecular synthon in a series of onium di(methane­sulfonyl)­amidates. The structure is pseudosymmetric; the anion positions correspond to space group P2₁/n, but those of the cations do not.     

Poly­sulfonyl­amines. CXLV.

The prominent features in the molecular structure of the title compound (alternative name: 2‐diethyl­carbamoyl‐1,1,3,3‐tetraoxo‐1,3,2‐benzodi­thia­zole), C₁₁H₁₄N₂O₅S₂, arise in the urea moiety S₂N—C(O)—N′C₂: the sum of the angles at N is 332.3 (1)°, the N—C(O)—N′C₂ unit is planar, and distances N—C(O) = 1.494 (3) Å, N′—C(O) = 1.325 (2) Å and C—O = 1.215 (2) Å. The mol­ecules are associated via five C—H?O hydrogen bonds to form layers parallel to the yz plane. This compound and its di­methyl homologue, which were synthesized by treating the silver salt of o‐benzene­disulfon­imide with carbamoyl chlorides, are prone to rapid hydro­lysis at the weak N—C(O) bond. For both mol­ecules, the rotational barrier about the partial N′—C(O) double bond is ca 50 kJ mol^?1 at 250 K (from dynamic ¹H NMR experiments).     

Kristallstrukturen des freien protonierten Liganden HN(SO2)2C6H4 (= HZ) und des lamellaren Caesiumsalzes CsZ

Metal Salts of Benzene‐1,2‐di(sulfonyl)amine. 3. Crystal Structures of the Free Protonated Ligand HN(SO₂)₂C₆H₄ (= HZ) and the Lamellar Cesium Salt CsZ Benzene‐1,2‐di(sulfonyl)amine ( 1 ; HZ), known since 1921, is a very strong NH acid and readily reacts with aqueous CsCl to form crystalline CsZ ( 3 ). For both compounds, crystal structures were determined by X‐ray diffraction at –100 °C ( 1 : monoclinic, space group P2₁/n, Z = 4; 3 : orthorhombic, Cmcm, Z = 4). In 1 , the five‐membered 1,3,2‐dithiazole heterocycle possesses an envelope conformation, the N atom lying 29.4(2) pm outside the mean plane of the S–C–C–S moiety [S–N 167.06(15) and 167.53(15) pm, S–N–S 114.57(8)°]. In the crystal, HZ molecules are linked into chains by a conventional N–H…O hydrogen bond and further associated via four weak C–H…O bonds to form a three‐dimensional network. The conjugate Z^⊖ ion in the layered structure of the salt 3 displays crystallographic C_2v symmetry, leading to an ideally planar bicyclic framework [S–N 158.29(15) pm, S–N–S 116.53(17)°]. Each of the five electronegative atoms bridges two cations, Cs^⊕ attaining a tenfold coordination by forming bonds to two (O,N,O)‐chelating and four κ¹O‐monodentate ligands. The Cs–O/N interactions create a polar [CsN(SO₂)₂]_∞ lamella, which is lipophilically wrapped by parallel benzo rings protruding perpendicularly from its surfaces. In contrast to the previously reported lamellar metal di(arenesulfonyl)amides, the aromatic groups pertaining to adjacent layers of 3 are seen to be markedly interlocked.     

Infrared absorption spectra of polymers from classical molecular simulation

A method is proposed to predict the infrared spectra of amorphous polymers. Based on classical molecular simulation and Kramers-Kronig relations, it allows the computations of absorption and transmittance spectra of polymer films in near and middle infrared domains with good agreement with experimental data.     

Eine Methode zur Darstellung und Bestimmung des Glykogens

Ohne Zusammenfassung     

Ichthyosan in fish eye

Ichthyosan A and V are two highly elastoviscous glycan complexes present in the aqueus and vitreus [here aqueus and vitreus are used as nouns as was suggested by Balazs and Denlinger in The eye, vol 1A. Vegetative physiology and biochemistry, 3rd edn. Academic Press, New York, pp 533–589, 1984] of the fish eye. Ichthyosan A, with its high elastic properties, surrounds and stabilizes the lens of the eye. Ichthyosan V, within the collagen fibers, serves as a structure stabilizer of the gel vitreus. These two molecular complexes are non-covalent aggregates composed of hyaluronan, a chondroitin-proteoglycan (sulfate free), and a keratan-like molecule. The ratio of hyaluronan to chondroitin–proteoglycan varies in the two ichthyosans. Electrophoretic separation methods (both free and gel electrophoresis) demonstrate that the hyaluronan–proteoglycan aggregates move as one molecular entity. The average molecular weight of the ichthyosan varies from 5.2 to 13.0 million in various species. Aquatic mammals do not have ichthyosan in their eyes.     

Dynamic updates of the barrier parameter in primal-dual methods for nonlinear programming

We introduce a framework in which updating rules for the barrier parameter in primal-dual interior-point methods become dynamic. The original primal-dual system is augmented to incorporate explicitly an updating function. A Newton step for the augmented system gives a primal-dual Newton step and also a step in the barrier parameter. Based on local information and a line search, the decrease of the barrier parameter is automatically adjusted. We analyze local convergence properties, report numerical experiments on a standard collection of nonlinear problems and compare our results to a state-of-the-art interior-point implementation. In many instances, the adaptive algorithm reduces the number of iterations and of function evaluations. Its design guarantees a better fit between the magnitudes of the primal-dual residual and of the barrier parameter along the iterations.     

Pyridinium salt liquid crystals Effect of mesogen extension and alkyl chain length

The thermotropism of 1-n-alkyl-(4-methyl and 4-tolyl)pyridinium bromides were compared for alkyl chain lengths ranging from n = 12 to 22 carbons. A smectic A mesophase is present in both series for the longer chain compounds, n ≥ 16, with the clearing temperature being similar for both series but increasing rapidly with chain length. The series with the elongated mesogen also possesses an ordered mesophase identified as smectic G. The transition between this mesophase and the S_A or isotropic phase in the 4-tolyl series, and the transition to and from the crystalline phase in both series, are affected relatively little by the alkyl chain length. It seems that the S_A mesophase is governed primarily by the amphiphilic character of the substances, whereas elongation of the ionic head group is responsible for the appearance of a more ordered mesophase at intermediate temperatures.     

What are the structural features of the active site that define binuclear copper proteins function?

The structural basis that define the physiological functions of binuclear copper enzymes is discussed in the frame of the data generated by a broad spectroscopic approach, spanning from paramagnetic NMR and pulsed EPR to x-ray absorption spectroscopies. The structural features discussed for the different oxidation and ligation states accessible to a binuclear copper sites are the coordination geometry for the first and second shell, the metal-metal distance and the role of the bridging exogenous ligand(s). A structural model will be presented to rationalize both the differentiation in function within the protein families and the reaction mechanism of those proteins that are enzymatically active.