Achiral Calcium‐Oxalate Crystals with Chiral Morphology from the Leaves of Some Solanacea Plants

The leaves of some plants, particularly among the Solanacea, contain crystals of calcium oxalate with a peculiar chiral pseudo‐tetrahedral morphology, even though the calcium oxalate crystal structure is centrosymmetric, hence achiral. We studied the morphology of these crystals extracted from the leaves of three Solanacea plants: the potato, the hot pepper, and a species of wild Solanum. The crystal morphology was the same in all three species. Based on the examination of more than 100 crystals from each plant, we showed that the crystal morphology is chiral with invariant chirality. We suggest that morphological chirality is induced by macromolecules during nucleation from a specific, genetically encoded crystal plane, and is further established during subsequent controlled crystal growth. This is one of few examples where it is possible to deduce a molecular mechanism for biologically induced breaking of morphological symmetry in organisms. A very high level of recognition is required by the macromolecules to allow them to distinguish between symmetry‐related crystal planes. It is also surprising that this finely controlled mechanism of crystal formation, including the chiral morphology, has been conserved during evolution.     

Electrochemical Immunoassay for Carbohydrate Antigen‐125 Based on Polythionine and Gold Hollow Microspheres Modified Glassy Carbon Electrodes

A new electrochemical immunosensor for the detection of carbohydrate antigen‐125 (CA125), a carcinoma antigen, was developed by immobilization CA125 antibody (anti‐CA125) on gold hollow microspheres and porous polythionine (PTH) modified glassy carbon electrodes (GCE). The gold hollow microspheres provided a biocompatible microenvironment for proteins, and greatly amplified the coverage of anti‐CA125 molecules on the electrode surface. The performance and factors influencing the immunosensor were investigated in detail. The detection is based on the current change before and after the antigen‐antibody interaction. Under optimal conditions, the amperometric changes were proportional to CA125 concentration ranging from 4.5 to 36.5 U/mL with a detection limit of 1.3 U/mL (at 3σ). The CA125 immunosensor exhibited good precision, high sensitivity, acceptable stability, accuracy and reproducibility. The as‐prepared immunosensors were used to analyze CA125 in human serum specimens. Analytical results suggest that the developed immunoassay has a promising alternative approach for detecting CA125 in the clinical diagnosis.     

Untersuchungen an Kristallhydraten anorganischer Salze, 8. Mitt. Interpretation der Schwingungsspektren vonM(BF4)2·6H2O fürM=Fe2+, Co2+, Ni2+

The infrared and Raman spectra were recorded in the range 4000–160 cm^–1 forM(BF₄)₂·6 H₂O whereM=Fe²⁺, Co²⁺, Ni²⁺. The spectroscopic data support the X-ray structural data in showing that in the crystal hydrates studied two kinds of hydrogen bonds are present: H₂O...H₂O and OH₂... F₄B^–. The energies and molecular force constants (f _OH and fH₂O) andr _OH for OH₂...F₄B^– were calculated for the three crystal hydrates. It was found that the bond OH₂... F₄B^– is comparatively weak, with mean energy 3.7–3.3 kcal/mol. Two types of water molecule with different structures are existing as the first are participating in H₂O...H–O–H...F₄B^– and the second in BF₄ ^–...H–O–H...F₄B^–.     

Strong Structural and Electronic Binding of Bovine Serum Albumin to ZnO via Specific Amino Acid Residues and Zinc Atoms

ZnO biointerfaces with serum albumin have attracted noticeable attention due to the increasing interest in developing ZnO-based materials for biomedical applications. ZnO surface morphology and chemistry are expected to play a critical role on the structural, optical, and electronic properties of albumin-ZnO complexes. Yet there are still large gaps in the understanding of these biological interfaces. Herein we comprehensively elucidate the interactions at such interfaces by using atomic force microscopy and nanoshaving experiments to determine roughness, thickness, and adhesion properties of BSA layers adsorbed on the most typical polar and non-polar ZnO single-crystal facets. These experiments are corroborated by force field (FF) and density-functional tight-binding (DFTB) calculations on ZnO-BSA interfaces. We show that BSA adsorbs on all the studied ZnO surfaces while interactions of BSA with ZnO are found to be considerably affected by the atomic surface structure of ZnO. BSA layers on the surface have the highest roughness and thickness, hinting at a specific upright BSA arrangement. BSA layers on surface have the strongest binding, which is well correlated with DFTB simulations showing atomic rearrangement and bonding between specific amino acids (AAs) and ZnO. Besides the structural properties, the ZnO interaction with these AAs also controls the charge transfer and HOMO-LUMO energy positions in the BSA-ZnO complexes. This ZnO facet-specific protein binding and related structural and electronic effects can be useful for improving the design and functionality of ZnO-based materials and devices.     

Low spin ferric hemoglobin complexes

A caloulation has been made of the energy eigenfunotions and eigenvalues of low spin ferric ion in complexes with a strong cubic crystal field including the effects of tetragonal and rhombic distortions and of spin-orbit coupling among the ground state components and with excited states. Using the resultant, spin-orbit coupled eigenfunotions as a basis set, the magnetic susceptibility, the components of magnetic field energy, and the lattice and valence contributions to an electric field gradient at the iron nucleus were all calculated as a function of rhombic, tetragonal, and spin-orbit coupling strength used as parameters: R, u and . All of the calculated results agree reasonable well with experiment for the values of parameters R=1000 cm^–1, u=2000 cm^–1 and the free ion value (=420 cm^–1. These values of parameters were selected for the excellent fit they gave of the calculated values of g _x, g_y and g _z compared with the experimental ones obtained from single crystal electron spin resonance of ferrihemoglobin azide. With them, a value of 2.29 Bohr magnetons was calculated for the effective magnetic moment compared to the experimental value of 2.35. The total field gradient calculated under the same conditions, predicts a nuclear quadrupole moment Q in the range of. 107 –127. Barns, which is smaller than the range predicted from the high spin ferric ion results. Reasons for this discrepancy are discussed.

---

Zusammenfassung Ausgehend von einem starken kubischen Ligandenfeld und unter Berücksichtigung tetragonaler (R) und rhombischer (u) Verzerrung sowie der Spin-Bahn-Kopplung () werden Eigenfunktionen und Energien fur Low-Spin-Ferrihämoglobinkomplexe berechnet. Mit den Parametern R=1000 cm^–1, u=2000 cm^–1, =420 cm^–1 erhält man für Suszeptibilität, elektrischen Feldgradienten am Fe und g-Werte gute Übereinstimmung mit experimentellen Daten. Aus dem berechneten Feldgradienten folgt ein Quadrupolmoment des Fe⁵⁷ von 0.107–0.127 Barn, im Gegensatz zu den viel höheren Resultaten bei High-Spin-Fe(III)-Verbindungen; diese Diskrepanz wird diskutiert.

---

Résumé Les fonctions propres et les énergies du complexe Ferrihémoglobine «low spin» sont calculées pour un fort champ de ligandes à symétrie cubique, en tenant compte des distortions tétragonale (R) et rhomboédrique (u), ainsi que du couplage spin-orbite (). Avec les parametres R=1000 cm^–1, u=2000 cm^–1, =420 cm^–1, on trouve pour la susceptibilité, le gradient du champ électrique à l'emplacement de Fe et le facteur g des valeurs en bon accord avec les données expérimentales. On déduit du gradient de champ calculé un moment quadrupolaire de Fe⁵⁷ de 0,107 à 0,127 Barn, en désaccord avec les résultats beaucoup plus élevés obtenus à partir des associations Fe (III) «high spin». Ce désaccord fait l'objet d'une discussion.

     

Interaction of nonionic detergents and swelling clays

Summary The 25° sorption isotherms of a polyoxyethylated n-dodecanol with 14 ethylene oxide units (C₁₂EO₁₄) on sodium and calcium montmorillonite were determined. Sorption complexes of the two clays were also prepared with C₁₂EO₃₀, n-dodecanol, polyethylene glycol and polypropylene glycol. X-ray powder diagrams show that the sorbed organic molecules are intercalated with their chains parallel to the montmorillonite lamellae, in layers one or two molecules thick. Sodium montmorillonite sorbs C₁₂ EO₁₄ and C₁₂EO₃₀ in excess of close-packed double layers: the excess detergent is occluded in interstices and absorbs moisture at 85% relative humidity to the same extent as the bulk detergents. The double layer complexes are not swelled by water; the single layer complexes sorb a single layer of water molecules at 85% relative humidity.Apparent densities of the sorbed organic molecules decrease with increasing EO content while bulk densities increase. This is explained in terms of chain flexibility and polarity.

---

Zusammenfassung Die 25°-Absorptions-Isothermen von polyoxyäthyliertem n-Dodekanol mit 14Äthylenoxyd-Einheiten(C₁₂EO₁₄) an Na- und Ca-Montmorillonit wurden bestimmt. Sorptions-Komplexe der 2 Tone wurden ebenfalls mit nDodekanol, Polyäthylenglykol und Polypropylenglykol präpariert. Pulverdiagramme zeigen, daß die sorbierten organischen Moleküle mit ihren Ketten parallel zu den Montmorillonitlamellen eingelagert sind, in Schichten 1 oder 2 Moleküle dick. Na-Montmorillonit sorbiert C₁₂EO₁₄ und C₁₂EO₃₀ im Überschuß zur dichtgepackten Doppelschicht. Der Überschuß ist in Hohlräumen eingelagert und absorbiert Wasser bei 85° relativer Feuchtigkeit im selben Ausmaß wie die reinen Detergentien. Die Doppelschichtkomplexe werden nicht durch Wasser gequollen. Die Einschichtkomplexe sorbieren eine Monoschicht von Wasser-Molekülen bei 85° relativer Luftfeuchtigkeit.Scheinbare Dichten der sorbierten organischen Moleküle nehmen mit steigendem Äthylenoxydgehalt ab, während die Dichten der reinen Substanz ansteigen. Dies läßt sich auf Grund der Kettenbeweglichkeit und Polarität erklären.

---

---

Presented at the 145^th Meeting of the American Chemical Society, New York, N. Y., September 1963.     

Zur Kenntnis der anomalen Reaktionen bei der Aminostickstoff-Bestimmung. IX. Die Reaktionen der Pyrrolin- und Oxazolinverbindungen mit salpetriger Säure

Zusammenfassung Es wurde die Reaktion von Pyrrolin- und Oxazolinverbindungen mit salpetriger Säure näher studiert, zumalTh. Wagner- Jauregg die Beobachtung machte, daß diese Verbindungen mit salpetriger Säure 1 Mol Stickstoff entwickeln, ohne daß eine primäre Aminogruppe vorhanden ist. Es zeigte sich, daß die Stickstoffentwicklung wie bei einem leicht desaminierbaren Amin schon bei 20° C schnell und vollständig vonstatten geht (Reaktion 1). Bei den Pyrrohnverbindungen ist ab 50° C noch eine weitere gasbildende Reaktion feststellbar, die bei 80 °C 1,40 Mole (N₂ + N₂O) liefert (Reaktion 2). Für die Reaktion 1 wird wahrscheinlich gemacht, daß sich zunächst eine in wäßriger Lösung unbeständige N-Nitrosoverbindung bildet. Bei deren Hydrolyse entsteht ein Diazoniumsalz, das unter Stickstoffentwicklung zerfällt. Dieses Reaktionsschema wird durch die Tatsache gestützt, daß bei Nitrosierung inwasserfreier Phase keine Stickstoffentwicklung erfolgt.Es wird weiters gezeigt, daß die Reaktion 2 (Gasentwicklung bei erhöhter Temperatur) durch die Folgeprodukte der Reaktion 1 verursacht wird. Bei diesen Folgeprodukten handelt es sich, wieWagner-Jauregg fand, um Acetonylverbindungen. Diese werden, wie wir bereits früher gezeigt haben, nitrosiert, wobei sich Isonitrosoverbindungen bilden. Die Isonitrosogruppe wird von überschüssiger salpetriger Säure unter Bildung von N₂ und N₂O zersetzt.Für die Aminostickstoffbestimmung ergibt sich daraus, daß Pyrrolinund Oxazolinverbindungen nur mit Nitrosylbromid in Eisessig (vgl.Kainz, Huber undKasler ¹⁵) richtig analysiert werden künnen, während die Bestimmung mit wäßriger Nitritlösung(van Slyke) ein Fehlresultat verursacht.

---

Summary A study was made of the reaction of pyrrolin- and oxazoline compounds with nitrous acid, especially sinceTh. Wagner- Jauregg observed that these compounds generate 1 mol of nitrogen with nitrous acid, though no primary amino group is present. It was observed that the evolution of nitrogen, as in the case of a readily deaminable amine, occurs rapidly and completely even at 20° C (reaction 1). With the pyrroline compounds, it was possible to demonstrate another gas-producing reaction from 50° C on, which yields 1.40 mols (N₂ + N₂O) at 80° C (reaction 2). It is probable that in reaction (1) there is formation of a N-nitroso compound instable in water solution, and that the hydrolysis of this primary product yields a diazonium salt, which decomposes with evolution of nitrogen. This reaction scheme is supported by the fact that no formation of nitrogen is observed on nitrosation in solutions containing no water.It was also shown that the reaction (2) (evolution of gas at raised temperature) is caused by the secondary product of reaction (1). In these latter products there are involved, as shown byWagner- Jauregg, acetonyl compounds, which as we have proved previously, are nitrosated with formation ofiso-nitroso compounds. Theiso-nitroso group is decomposed by excess nitrous acid with production of N₂ and N₂O.With respect to the determination of amino nitrogen, it was found that pyrroline- and oxazoline compounds can be correctly analyzed only with nitrosyl bromide in glacial acetic acid (compareKainz, Huber, andKasler ¹⁵), whereas the determination with aqueous nitrite solution(van Slyke) brings about an incorrect result.

---

Résumé Les auteurs ont poussé l'étude de la réaction des dérivés de la pyrroline et de l'oxazoline avec l'acide nitreux à partir de l'observation deTh. Wagner-Jauregg suivant laquelle ces combinaisons réagissent sur l'acide nitreux en dégageant une molécule d'azote en l'absence de tout groupe aminé primaire. Il est apparu que le dégagement d'azote se produit rapidement et complètement à 20° C comme pour une amine réagissant facilement (Réaction 1). Pour les combinaisons de la pyrroline une autre réaction commençant à partir de 50° C et donnant lieu à la formation de gaz a pu être établie; à 80° C, elle donne naissance à 1,40 molécule du mélange (N₂ + N₂O) (Réaction 2). Pour la réaction 1 il est vraisemblable qu'il se produit tout d'abord en solution aqueuse une combinaison N-nitrosée instable. Son hydrolyse produit un sel de diazonium qui se décompose avec dégagement d'azote. Ce schéma réactionnel est confirmé par le fait que par nitrosation en phase non aqueuse il ne se produit aucun dégagement d'azote.Il a été en outre montré que la réaction 2 (dégagement de gaz par élévation de température) est dûe aux produits formés dans la réaction 1. Parmi ces produits, se trouvent, comme l'ont montréWagner-Jauregg, des combinaisons acétonylées. Ces dernières, comme nous l'avons déjà montré antérieurement, se nitrosent en donnant lieu à la formation de combinaisons isonitrosées. Le groupement isonitrosé est décomposé par l'acide nitreux en excès avec formation de N₂ et de N₂O. Pour la détermination de l'azote aminé, il en résulte que les dérivés de la pyrroline et de l'oxazoline ne peuvent être correctement analysés qu'en employant du bromure de nitrosyle en solution dans l'acide acétique (cf.Kainz, Huber etKasler ¹⁵) tandis que la détermination par action d'une solution aqueuse de nitrite (van Slyke) fournit un résultat erroné.

---

---

VIII. Mitteilung: Anomalie einiger Aminosäuren¹.     

Solid State Regeneration of Carbonyl Compounds from Oximes and Semicarbazones with Poly [N‐Bromo‐Benzene‐1,3‐Disulfonylamide]

Poly [N‐bromo‐benzene‐1,3‐disulfonylamide] [ PBBS ] is a novel and efficient reagent for the conversion of oximes and semicarbazones under solid state to their corresponding carbonyl compounds in high yields.     

贫电子环丙烷衍生物与胂叶立德的反应研究

The reaction of electron-deficient cyclopropane derivatives, cis-1-methoxycarbonyl-2-aryl-6,6-dimethyl-5,7dioxospiro[2,5]octa-4,8-diones with benzoylmethylenetriphenylarsorane (2) and methoxycarbonylmethylenetriphenylarsorane (4) was found to form cis,trans-l-methoxycarbonyl-2-aryl-3-benzoyl-7,7-dimethyl-6,8-dioxospiro[3,5]nona-5,9-dione (3a-3e) and trans,cis,trans-5-[2‘-methoxycarbonyl-2‘-(triphenylarsoranylidene)acetyl]-6oxo-3-aryl-tetrahydro-pyran-2,4-dicarboxylic acid dimethyl esters (5a-5c) respectively with high stereoselectivity. The possible reaction mechanisms for the formation of the different products were also orooosed.     

X-H (X = C, N, O, Si, P, S) 键离解能计算的密度泛函方法研究

使用了不同密度泛函方法计算X-H (X = C, N, O, Si, P, S) 键离解能，并分析不同密度泛函方法的计算精度。研究发现大多数密度泛函方法包括B3LYP, B3P86, B3PW91, G96LYP, PBE1PBE，和BH&HLYP都明显低估键离解能13-25 kJ/mol。该现象与是否使用无限基组无关，因为即使使用无限基组键离解能仍然被低估。因此密度泛函方法不适合用于键离解能的估算。其中B3P86方法的偏差最小。进一步分析表明，使用限制性开壳层计算并无任何优势，在大多数情况下非限制性开壳层计算实际上比限制性开壳层计算要好。最后，我们发现了密度泛函方法对键离解能的低估是系统的，因此建议利用校准后的UDFT/6-311++G(d, p)方法计算化学键离解能。