Crystal and Molecular Structures of Di-1-Adamantylthiophosphinic Chloride, <Emphasis Type="Italic">P</Emphasis>,<Emphasis Type="Italic">P</Emphasis>-Diphenyl-<Emphasis Type="Italic">N</Emphasis>-Benzyl Phosphinothioic- and Selenoic- Amides

Abstract  Synthesis and X-ray structural determination of three phosphorus compounds are reported. (3b) is monoclinic P2(1)/c with a = 11.852(1), b = 12.825(1), c = 12.445(1) ?, β = 103.693(1)o; (4a) and (4b) are monoclinic P2(1)/n with a = 12.1422(16), b = 9.0860(12), c = 14.845(2) ?, β = 96.498(3)o for (4a), and a = 12.2714(16), b = 9.2812(12), c = 14.800(2) ?, β = 97.176(2)o for (4b). They all exhibit distorted tetrahedral geometry about the P atom. Ph₂P(X)NHC₇H₇ (X=S (4a) and X=Se (4b)) show typical P–S and P–Se double bond distances and P–N single bonds, while P–S bond in 1-Ad₂P(S)Cl (3b) is comparable to P–S single bonded probably due to the largeness of 1-adamantyl groups. Graphical Abstract  Synthesis and X-ray structural determination of 1-Ad₂P(S)Cl (3b), Ph₂P(S)NHC₇H₇ (4a) and Ph₂P(Se)NHC₇H₇ (4b) are reported.      

Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO)

Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S](2+,1+) cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S](+) cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S](+) between 8 and 18K and for semiquinone between 25 and 65K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S](+) were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S](+) and obtain point-dipole interspin distances of 18.6+/-1A for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.     

Quantification of cerebral perfusion using the "bookend technique": an evaluation in CNS tumors

We present a method of quantifying cerebral blood volume using dynamic susceptibility contrast. Our approach combines T₂-weighted echo planar imaging (EPI) pulse sequences and reference scans that determine the parenchymal T₁ changes resulting from an injection of a gadolinium chelate. This combined T₂- and T₁-weighted approach (the “bookend” technique) has been shown to be effective in the quantification of gradient-echo (GRE) (T₂*-weighted) perfusion images but has not been applied to spin-echo EPI (SE-EPI) (T₂-weighted) images. The physics related to blood volume measurement based on T₂- and T₂*-weighted EPI sequences is known to be different, and there is a question as to whether the bookend approach is effective with SE-EPI. We have compared the quantitative SE-EPI with GRE-EPI in a series of patients with central nervous system (CNS) tumors. We found that quantitative cerebral blood volume (qCBV) values for SE-EPI and GRE-EPI are in agreement with each other and with historical reference values. A subjective evaluation of image quality showed that image quality in the SE-EPI scans was high and exhibited high interreader agreement. We conclude that measuring qCBV using the bookend technique with SE-EPI images is possible and may be a viable alternative to GRE-EPI in the evaluation of CNS tumors.     

Mistimed stimulated echoes and distorted spin-alignment spectra of powdered solids

It is commonplace that NMR echo maxima appear at times for which the dephasing and the rephasing periods of a pulse sequence are equally long. However, for stimulated echoes a significant time shift from this naively expected echo position can be observed if the dephasing times are smaller than the inverse line width of the NMR spectrum. This effect, which will be observable for any line shape, is evaluated quantitatively for Gaussian and for Pake-like patterns. Comparison of the calculations is made with experimental results from (6)Li- and from (2)H-NMR and excellent agreement is found. In the simultaneous presence of broad and narrow lines, the apparent time shift can give rise to characteristic distortions in spin-alignment spectra. This explains some features previously observed using (7)Li-NMR.     

The Resting State Makes the Difference: The Influence of the Anchor Group in the ROMP of Norbornene Derivatives

Summary: A model study with four norbornene derivatives with different groups connecting a functional unit to the norbornene reveals that the “anchor groups” influence the polymerisation rate constants of ring opening metathesis (ROM) polymerisations. Consequently, polydispersities and molecular weights are affected. The observed effects are explained by different tendencies of the anchor groups to coordinate to the ruthenium centre during the resting state of the propagation.

A functionalised monomer where F is the functional unit, S is a spacer, A is an anchor group and P is the polymerisable group.     

Synthesis and Anti-HIV Activity of a Novel Series of Isoquinoline-Based CXCR4 Antagonists

An expansion of the structure–activity relationship study of CXCR4 antagonists led to the synthesis of a series of isoquinolines, bearing a tetrahydroquinoline or a 3-methylpyridinyl moiety as head group. All compounds were investigated for CXCR4 affinity and antagonism in competition binding and calcium mobilization assays, respectively. In addition, the anti-HIV activity of all analogues was determined. All compounds showed excellent activity, with compound 24c being the most promising one, since it displayed consistently low nanomolar activity in the various assays.     

Fractionated Lignosulfonates for Laccase-Catalyzed Oxygen-Scavenging Films and Coatings

Lignin derivatives have potential as antioxidants in advanced packaging materials through their ability to scavenge oxygen in reactions catalyzed by phenol-oxidizing enzymes, such as laccase. The effects of size fractionation of lignosulfonates on laccase-catalyzed reactions were investigated in experiments with aqueous solutions, films, and coated paperboard. Four industrial lignosulfonate preparations were compared: Feed (unfractionated), Prod (5–60 kDa enriched), Conc (≥60 kDa enriched), and Perm (≤60 kDa enriched). Extraction of lignosulfonates from films showed that the enzymic reaction increased the average molecular weight from <10,000 to up to 66,000. The enzymatic reaction resulted in an increase in the water contact angle of the films from the range 25–49° to 56–81°. The four preparations showed relatively small differences with regard to their ability to scavenge oxygen in aqueous solution and in experiments with coated paperboards in sealed chambers. Coatings with lignosulfonates where the contents of low-molecular weight material had been reduced (i.e., Prod and Conc) showed improved water resistance after the enzymic reaction. Thus, in both aqueous and solid media, fractionation of lignosulfonates had little effect on oxygen scavenging, but fractionation was beneficial for other reasons, such as improved cross-linking resulting in higher molecular weight and superior water resistance.     

Impact of Metallic Nanoparticles on In Vitro Culture,Phenolic Profile and Biological Activity of Two Mediterranean Lamiaceae Species: Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales

Nanoparticles (NPs) recently emerged as new chemical elicitors acting as signaling agents affecting several processes in plant metabolism. The aim of this work was to investigate the impact of the addition of copper oxide (CuO), zinc oxide (ZnO) and iron oxide (Fe₃O₄) NPs (<100 nm) at different concentrations (1, 5 and 10 mg/L) to the culture media on several morphological, physiological and -biochemical parameters of in vitro shoot cultures of Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales (Lamiaceae), as well as on phenolic profile and bioactivity (antioxidant and enzyme inhibition capacities). Although some decreases in shoot number and length were observed in response to NPs, biomass production was not affected or was improved in both species. Most NPs treatments decreased total chlorophyll and carotenoid contents and increased malondialdehyde levels, an indicator of lipid peroxidation, in both species. HPLC-HR-MS analysis led to the identification of thirteen and twelve phenolic compounds, respectively, in L. viridis and T. lotocephalus extracts, being rosmarinic acid the major compound found in all the extracts. ZnO and Fe₃O₄ NPs induced an increase in total phenolic and rosmarinic acid contents in T. lotocephalus extracts. Additionally, some NPs treatments also increased antioxidant activity in extracts from this species and the opposite was observed for L. viridis. The capacity of the extracts to inhibit tyrosinase, acetylcholinesterase and butyrylcholinesterase enzymes was not considerably affected. Overall, NPs had a significant impact on different parameters of L. viridis and T. lotocephalus in vitro shoot cultures, although the results varied with the species and NPs type.     

Structure and Photochemical Behavior of the Cyclodextrin Inclusion Complexes of the Benzoylthiophene‐Derived Drugs Tiaprofenic Acid (=5‐Benzoyl‐α‐methylthiophene‐2‐acetic Acid) and Suprofen (=α‐Methyl‐4‐(2‐thienylcarbonyl)benzeneacetic Acid)

The effect of β‐cyclodextrin (β‐CD) on the excited‐state reactivity of the two benzoylthiophene derivatives, tiaprofenic acid (TPA; 2 ) and suprofen (SPF; 3 ) in their carboxylate forms is studied. The presence of β‐cyclodextrin does not affect the nature of the photoproduced transients and the photoproducts, but increases the photodegradation quantum yields of both drugs. The efficiency of the photodecarboxylation process is enhanced. This effect is rationalized in the light of the inclusion of 2 and 3 in the β‐CD cavity, affecting the energy of the lowest excited states of the drugs. The structure of the complexes is determined by induced circular dichroism, and molecular‐mechanics and dynamic Monte Carlo calculations. The photoreactivity of the decarboxylated photoproduct 7 of tiaprofenic acid ( 2 ) in presence of β‐CD is also examined.