Two-photon fluorescence polarisation and stimulated emission depletion dynamics are investigated in three high two -photon cross-section push-push polyenes: OM62, LP79 and OM77 and compared to the behaviour of a standard fluorophore (rhodamine 6G). Two-photon fluorescence anisotropy measurements (R(0) and Ω) were undertaken using picosecond time-correlated single photon counting (TCSPC). For OM...

The explicit form of the zeroth Green's function in the Hückel model, approximated by the negative of the inverse of the Hückel matrix, has direct quantum interference consequences for molecular conductance. We derive a set of rules for transmission between two electrodes attached to a polyene, when the molecule is extended by an even number of carbons at either end (transmission unchanged) or ...

Detailed density functional theory (DFT) calculations on the structure and harmonic frequencies of model all-trans and all-cis polyenes were undertaken. For the first time, we report on the convergence of selected B3LYP/6-311++G** and BLYP/6-311++G** calculated structural parameters resulting from a systematic increase in polyene size (chains containing 2 to 14 C = C units). The limiting values...

We describe the joint application of the density matrix renormalization group and canonical transformation theory to multireference quantum chemistry. The density matrix renormalization group provides the ability to describe static correlation in large active spaces, while the canonical transformation theory provides a high-order description of the dynamic correlation effects. We demonstrate th...

On adsorption of some electron-acceptor molecules on the solid films of all-trans-beta-carotene, beta-apo-8'-carotenal, astacene and methylbixin a new absorption band appears on the longer-wavelength side of the spectrum in addition to the original bands. The position of this new band is dependent on the electron affinity (EA) of the acceptor molecules, and the intensity of this band increases ...

We have examined the effects of the sterol-binding polyene antibiotics on macrophage tumoricidal capability. Incubation for 2 hr of activated macrophages from bacillus Calmette-Guérin-infected mice with amphotericin B at 0.5--2 microgram/ml or amphotericin B methyl ester at 0.5--10 microgram/ml enhanced the capability of activated macrophages to kill 3T12 cells. These polyenes did not make norm...

[2+2] Photocycloaddition of olefins is a very useful reaction in synthetic organic chemistry to obtain cyclobutane-containing molecules, which are almost inaccessible by other methods. The reaction, when performed in the crystalline state, occurs more efficiently and selectively than in homogeneous solution due to tight and regular molecular arrangement in the crystal state. Despite numerous ex...

The production of interferon by polyriboinosinic-polyribocytidylic acid [poly(I) . poly(C)] and poly(I) . poly(C)-diethylaminoethyl-dextran in L929 cells was enhanced from 10 to 100 times by polyene macrolides, including amphotericin B (AmB), AmB methyl ester, nystatin, and filipin. AmB and its water-soluble methyl ester were the most effective; retinol, a nonmacrolide polyene, was ineffective....