Hydroxamic acid polymers. II. Design of a polymeric chelating agent for iron

The iron chelating ability of hydroxamic acid polymers was studied as a function of the atomic chain spacing separating neighboring hydroxamic acid units. Two polymers were prepared, one having the hydroxamic acid group separated by 11 atoms and the other by three atoms. The iron binding of these polymers was compared with the model compound desferrioxamine B (DFO) and with a previously prepared polymer having a nine-atom spacing. Mole ratio plots indicated the following order of stability: DFO ≈ 11 atom > 9 atom > 3 atom. These results are in accordance with the picture derived from molecular models which shows that with a spacing of 11 atoms, three neighboring hydroxamic acids can fit the octahedral arrangement of the iron (III) complex without appreciable strain. Some strain is introduced when the spacing becomes only nine atoms, and with three atoms, complex formation between three neighboring groups becomes virtually impossible.     

ENHANCED SUSCEPTIBILITY TO HPD-SENSITIZED PHOTOTOXICITY AND CORRELATED RESISTANCE TO TRYPSIN DETACHMENT IN SV-40 TRANSFORMED IMR-90 CELLS

Abstract— The response of a normal human cell strain, IMR-90 and a line derived from it by SV40 transformation were compared after treatment in vitro with hematoporphyrin derivative (HPD) and red light. Transformed cells were inactivated at a significantly higher rate than normal cells when assayed by clonogenic survival. Co-treatment with HPD and light also induces cellular resistance to enzymatic cleavage by trypsin; transformed cells exhibit a greater resistance than the normal cells to detachment from the growing surface. These data indicate that transformed cells may possess intrinsic characteristics that render them more sensitive than normal cells to HPD-induced phototoxicity and that the plasma membrane may be the site of differential toxicity.     

Broadband rotational resonance in solid state NMR spectroscopy

A new technique for restoring nuclear magnetic dipole-dipole couplings under magic-angle spinning (MAS) in solid state nuclear magnetic resonance (NMR) spectroscopy is described and demonstrated. In this technique, called broadband rotational resonance (BroBaRR), the coupling between a pair of nuclear spins with NMR frequency difference close (but not necessarily equal) to the MAS frequency is restored by the application of a train of weak radio-frequency pulses at a carrier frequency close to the average of the two NMR frequencies. Phase or amplitude modulation of the pulse train at half the MAS frequency splits the carrier into sidebands close to the two NMR frequencies. The pulse train then removes offsets from the exact rotational resonance condition, leading to dipolar recoupling over a bandwidth controlled by the amplitude of the pulse train. (13)C NMR experiments on uniformly (15)N,(13)C-labeled L-valineHClH(2)O powder validate the theoretical analysis. BroBaRR will be useful in studies of molecular structures by solid state NMR, for example in the detection of long-range couplings between carbons in uniformly labeled organic and biological materials.     

PHOTOBLEACHING OF MONO-l-ASPARTYL CHLORIN e6 (NPe6): A CANDIDATE SENSITIZER FOR THE PHOTODYNAMIC THERAPY OF TUMORS

Abstract— Most sensitizers used for the photodynamic therapy (PDT) of tumors photobleach on illumination. Thus, it is of interest to examine the photobleaching behavior of new sensitizers proposed for use in PDT. This report surveys the quantum yields and kinetics of the photobleaching of mono- l -aspartyl chlorin e₆ (NPe6), a hydrophilic chlorin that has many of the photoproperties desirable in a sensitizer for clinical PDT. It is a very effective sensitizer for the PDT of several types of model tumors in animals and is now in Phase I clinical trials. The quantum yield of NPe6 photobleaching in pH 7.4 phosphate buffer in air was 8.2 × 10⁻⁴; this is greater than the yields for typical porphyrin photosensitizers. For example, the yields for hematoporphyrin and uroporphyrin are 4.7 × 10 ⁵ and 2.8 × 10⁻⁵, respectively. The yield decreased significantly in organic solvents of low dielectric constant. The Sn derivative of NPe6 was more light stable than NPe6 (yield = 5.7 × 10 ⁻⁶), while the Zn derivative was more sensitive (yield = 1.9 × 10⁻²). Oxygen appeared to be necessary for the photobleaching of NPe6; however, bleaching was not inhibited by 100 mM azide, an efficient quencher of singlet oxygen. The photooxidizable substrates cysteine, dithiothreitol and furfuryl alcohol increased the quantum yield of photoblcaching two- to four-fold, while the electron acceptor, met-ronidazole, increased it almost six-fold. Photobleaching yields for several other chlorins were also measured.     

Anion-sealed single-molecule capsules

A new approach to anion recognition utilizing electrostatic and hydrogen bonding interactions has been demonstrated by placement of the whole ion-pair in a molecular capsule.     

Organic synthesis on the microgram scale. IX

Summary Synthesis of acetanilide and analogs in good yields has been carried out ing amounts by reacting the aromatic amines with an acetic anhydride-acetic acid mixture. After TLC separation on the same vehicle, the products can be visualized by ultraviolet radiation or by color reactions. A procedure is also described to recover the acetanilides for obtaining infrared spectra by the attenuated total reflection technique.

---

Zusammenfassung Die Synthese von Acetanilid und analogen Substanzen wurde mit guter Ausbeute in Mikrogrammengen durchgeführt. Man läßt das aromatische Amin mit einer Mischung von Acetanhydrid und Essigsäure reagieren. Nach DC-Trennung in diesem Laufmittel kann man die Reaktionsprodukte im UV oder durch eine Farbreaktion sichtbar machen. Außerdem wurde ein Verfahren beschrieben, die Acetanilide für die IR-Spektroskopie nach der ATR-Methode wiederzugewinnen.

---

---

For Part VIII see Mikrochim. Acta [Wien]1971, 662.     

Polybenzodipyrroloquinoxalines

Three polymers have been prepared by the condensation of benzo[1,2-b;5,4-b ′]-dipyrrolo-2,3,4,5-tetraone (I) with 1,2,4,5-tetraaminobenzene (II), 3,3 ′-diaminobenzidine (III), and 3,3 ′,4,4 ′-tetraaminodiphenyl ether (IV) in polyphosphoric acid (PPA) solution. The polymer structures were substantiated by comparison of their infrared and ultraviolet spectra with spectra of the model compounds and elemental analysis. The polymers had inherent viscosities of 0.86-0.90 (H₂SO₄) and thermal stabilities of 460°C and up to 700°C in air and nitrogen atmospheres, respectively.     

Identification of hydrolyzed inulin syrup and high-fructose corn syrup in apple juice by capillary gas chromatography: PVM 4:1999

A peer-verified, gas chromatographic (GC) method is presented for the identification of hydrolyzed inulin syrup (HIS) and high-fructose corn syrup (HFCS) in apple juice. The procedure involves determining the Brix value of the apple juice or apple juice concentrate and preparing a dilution of the test sample to 5.5 degrees Brix. A 100 microL aliquot of the 5.5 degrees Brix test solution is then freeze-dried in a GC autosampler vial. The sugars in the freeze-dried residue are converted to trimethylsilyl derivatives, by the addition of an appropriate silylation reagent, and the vial is heated at 75 degrees C for 30 min. After derivatization, the solution is introduced into a gas chromatograph where the analytes are separated on a 30 m, 0.25 mm id DB-5 column. The method can use hydrogen, helium, or nitrogen as the carrier gas. The analytes and marker compounds are measured by use of a flame ionization detecone of the 2 syrups at 2 levels. Dilution was ascertained by the presence of retrograde sugar markers found in the 2 sugar syrups. All 3 laboratories involved in the study were able to identify the correct diluent in the blind, randomly coded, apple juice test portions. The levels of dilution in the test portions were 0, 6.9% (HIS), 16.0% (HIS), 8.1% (HFCS), and 17.0% (HFCS). No false positive results were reported. Quantitative conclusions can be drawn when the same syrup is used for dilution and as a reference standard.     

Synthesis and Characterization of the Isocyanide Ligated Centered Zirconium Halide Cluster [(Zr6Be)Cl12(CNXyl)6]

The first isocyanide ligated hexanuclear zirconium halide cluster is reported. The unoxidized [(Zr₆Be)Cl₁₂(CNXyl)₆] (CNXyl = 2,6-dimethylphenyl isocyanide) was obtained from the solid state precursor K₃Zr₆Cl₁₅Be by dissolution in CH₃CN in the presence of CNXyl. The CNXyl ligands occupy all the axial positions on the cluster. The compound was recrystallized from CH₂Cl₂ and Et₂O. [(Zr₆Be)Cl₁₂(CNXyl)₆].2CH₂Cl₂ crystallizes in the space group (#2) with a = 12.092(5) Å, b=12.728(5) Å, c = 14.102(8) Å, = 104.98(4)°, =107.11°, = 100.94°, V = 1919(2) ų, Z = l, R = 11.3% and R _W = 27.0%. For the bound isocyanide ligands, v _CN increases to 2140 cm^–1.     

Polyarylaminophosphazene copolymers

A series of polyarylaminophosphazene copolymers have been prepared and are described. In each preparation, two arylamines were allowed to competitively react with polydichlorophosphazene, and the substituent ratios of the resulting copolymers, determined by high-temperature ¹H-NMR spectroscopy, generally reflect expected steric and electronic effects on the relative reactivities of the arylamines studied. The copolymers have intrinsic viscosities of 0.64–1.25 dl/g, glass transition temperatures of 75–104°C, and decomposition temperatures of 220–260°C. These properties, which are comparable to those of polyarylaminophosphazene homopolymers, are discussed in regard to what they may reflect about the structure of the polymers.