50606-97-8

Photoinduced charge separation (CS) and charge recombination (CR) processes have been examined in various porphyrin-fullerene linked systems (i.e., dyads and triads) by means of time-resolved transient absorption spectroscopy and fluorescence lifetime measurements. The investigated compounds comprise a homologous series of rigidly linked, linear donor-acceptor arrays with different donor-acceptor separations and diversified donor strength: freebase porphyrin-C60 dyad (H2P-C60), zincporphyrin-C60 dyad (ZnP-C60), ferrocene-zincporphyrin-C60 triad (Fc-ZnP-C60), ferrocene-freebase porphyrin-C60 triad (Fc-H2P-C60), and zincporphyrin-freebase porphyrin-C60 triad (ZnP-H2P-C60). Most importantly, the lowest lying charge-separated state of all the investigated systems, namely, that of ferrocenium ion (Fc+) and the C60 radical anion (C60?-) pair in the Fc-ZnP-C60 triad, has been generated with the highest quantum yields (close to unity) and reveals a lifetime as long as 16 μs. Determination of CS and CR rate constants, together with the one-electron redox potentials of the donor and acceptor moieties in different solvents, has allowed us to examine the driving force dependence (-ΔG0ET) of the electron-transfer rate constants (kET). Hereby, the semilogarithmic plots (i.e., log kET versus-ΔG0ET) lead to the evaluation of the reorganization energy (γ) and the electronic coupling matrix element (V) in light of the Marcus theory of electron-transfer reactions: γ = 0.66 eV and V = 3.9 cm-1 for ZnP-C60 dyad and γ = 1.09 eV and V = 0.019 cm-1 for Fc-ZnP-C60, Fc-H2P-C60, and ZnP-H2PC60 triads. Interestingly, the Marcus plot in Fc-ZnP-C60, Fc-H2P-C60, and ZnP-H2P-C60 has provided clear evidence for intramolecular CR located in both the normal and inverted regions of the Marcus parabola. The coefficient for the distance dependence, of V (damping factor: βCR = 0.58 A-1) is deduced which depends primarily on the nature of the bridging molecule.

PLK1, polo-like kinase 1, is a central player regulating mitosis. Inhibition of the subcellular localization and kinase activity of PLK1 through the PBD, polo-box domain, is a viable alternative to ATP-competitive inhibitors, for which the development of resistance and inhibition of related PLK family members are concerns. We describe novel nonpeptidic PBD-binding inhibitors, termed abbapolins, identified through successful application of the REPLACE strategy and demonstrate their potent antiproliferative activity in prostate tumors and other cell lines. Furthermore, abbapolins show PLK1-specific binding and inhibitory activity, as measured by a cellular thermal shift assay and an ability to block phosphorylation of TCTP, a validated target of PLK1-mediated kinase activity. Additional evidence for engagement of PLK1 was obtained through the unique observation that abbapolins induce PLK1 degradation in a manner that closely matches antiproliferative activity. Moreover, abbapolins demonstrate antiproliferative activity in cells that are dramatically resistant to ATP-competitive PLK1 inhibitors.

Fluids with spontaneous helical structures formed by achiral low molecular mass molecules is a newly emerging field with great application potential. Here, we explore the chemical mechanisms of the helix formation by systematically modifying the structure of a bent 4-cyanoresorcinol unit functionalized with two different phenyl benzoate based aromatic rods and terminated with two alkyl chains of variable length. The majority of these achiral compounds self-assemble, forming a short-pitch heliconical liquid crystalline phase in broad temperature ranges. In some cases, it occurs without any competing low-temperature phase. We demonstrate that the mirror symmetry broken mesophase occurs at the paraelectric-(anti)ferroelectric transition if the tilt angle of the molecules in the smectic layers is around 18-20° and if this transition coincides with a change of the tilt correlation between the layers. In the close vicinity of this transition, a field-induced heliconical phase develops as well as a new heliconical phase with polarization-randomized structure. These investigations provide a blueprint for the future design of achiral molecules capable of spontaneous mirror symmetry breaking by the formation of heliconical liquid crystalline phases.

A library of 33 compounds was screened for potentiation of the antibiotic FR 900098 against the Francisella tularensis surrogate Francisella novicida. From the screen a highly potent 2-oxazoline adjuvant was discovered capable of potentiating FR 900098 with a 1000-fold reduction in MIC against the Francisella sub-species F. novicida and F. philomiragia.

The design, synthesis, and evaluation of the potency of new isoform-selective inhibitors of sphingosine kinases 1 and 2 (SK1 and SK2), the enzyme that catalyzes the phosphorylation of d-erythro-sphingosine to produce the key signaling lipid, sphingosine 1-phosphate, are described. Recently, we reported that 1-(4-octylphenethyl)piperidin-4-ol (RB-005) is a selective inhibitor of SK1. Here we report the synthesis of 43 new analogues of RB-005, in which the lipophilic tail, polar headgroup, and linker region were modified to extend the structure-activity relationship profile for this lead compound, which we explain using modeling studies with the recently published crystal structure of SK1. We provide a basis for the key residues targeted by our profiled series and provide further evidence for the ability to discriminate between the two isoforms using pharmacological intervention.

Imidamide (amidine) analogs that can inhibit the activity of sphingosine kinase 1 and sphingosine kinase 2 (SphK1 and SphK2) are provided. The compounds can prevent angiogenesis in tumors.

Sphingosine 1-phosphate (S1P), a potent phospholipid growth and trophic factor, is synthesized in vivo by two sphingosine kinases. Thus these kinases have been proposed as important drug targets for treatment of hyperproliferative diseases and inflammation. We report here a new class of amidine-based sphingosine analogues that are competitive inhibitors of sphingosine kinases exhibiting varying degrees of enzyme selectivity. These inhibitors display KI values in the submicromolar range for both sphingosine kinases and, in cultured vascular smooth muscle cells, decrease S1P levels and initiate growth arrest.

The invention discloses optically active liquid crystal compounds represented by the formulas [I], [II] and [III]: STR1 wherein R1 and R2 each represents an alkyl group of 4-18 carbon atoms, X represents O, COO or a single bond, and (A), (B), (C), (D) and (E) each represents STR2 in which l represents a halogen. The invention further discloses optically active liquid crystal compounds which are able to exhibit tristable states, represented by the formulas [IV], [V] and [VI]: STR3 wherein R1 ' and R2 ' each represents a straight chain alkyl group of 5-16 carbon atoms, X' represents O or COO and (A), (B), (C), (D) and (E), and l each has the same meaning as above.

Intermolecular Friedel-Crafts acylation of various substituted alkyl- or alkoxybenzenes with oxalyl chloride using carbon disulfide as solvent gave rise to the benzils 1a-k.Subsequent intramolecular oxidative coupling with either thallium(III) oxide/trifluoroacetic acid or vanadium(V) oxyfluoride/boron trifluoride diethyl etherate resulted in the corresponding phenanthrene-9,10-diones 2a-d.It has been shown that oxygen functionalities at the 3,3',4, and 4'positions are necessary for coupling to occur.These substituted benzils and phenanthrene-9,10-diones constitute precursors for ligands in the field of discotic metallomesogens or polymeric mesogens.

The present invention is characterized by a smectic liquid crystal compound represented by the following formula: STR1 wherein R is selected from alkyl and alkoxy groups; X from STR2 m and n are natural numbers; and R* is an optically active group containing an asymmetric carbon atom, and a liquid crystal composition containing said compound as a component. This compound is excellent in optical stability and high-speed response.

The preparation of unbranched 4-alkylbenzaldehydes free of positional and branched-chain isomers by different methods is described.A one-step preparation of the aldehydes is reported which involves the direct hydrogenation of a Friedel-Craft's complex in the presence of Pd/C catalyst.

There is provided a process for preparing amides which comprises reacting an amine, or an amide, and an acid halide, or anhydride, in suitable molecular proportions, in an inert organic diluent, in the presence of an effective amount of a molecular sieve, until the reaction is completed, separating the molecular sieve, and recovering the amide from the organic mother liquor.

A new series of fluorine containing phenyl benzoates has been synthesized and the transition temperatures of these compounds have been determined.A series of 4-trifluoromethylphenyl 4-n-alkylbenzoates showed no liquid crystalline behaviour, but the 4-trifluoromethylphenyl 4-n-alkoxybenzoates series, with six carbons or more in alkoxy chain, was mesomorphic.The 4-cyanophenyl 4-perfluoroalkylbenzoates showed smectic liquid crystalline properties.

A homologous series of 4-alkyl or alkoxy-4 prime -bromo or cyanotolanes in which the alkyl group is C//4 yields C//1//0 and the alkoxy group is C//1 yields C//1//2, was prepared. Interphase transitions between solid, mesomorphic and isotropic phases were studied by hot stage microscopy and differential scanning calorimeter. The bromo compounds have a smectic polymorphism. Three pure products of cyano derivatives with the chains C//9H//1//9O, C//1//0H//2//1O amd C//1//0H//2//1 present an enantiotropic or monotropic reentrant nematic phase at atmospheric pressure. The reentrant phenomenon itself is discussed as well as the absence of correlation between T//N//A/T//N//I McMillan parameter and the heat of transition. A plot of the nematic isotropic transition temperatures against the number of carbon atoms in the alkoxy chain shows the usual odd even effect.