We review our recent low-temperature absorption, circular dichroism (CD), magnetic CD (MCD), fluorescence and laser-selective measurements of oxygen-evolving Photosystem II (PSII) core complexes and their constituent CP 4 3, CP 47 and D1/D2/cytb(559) sub-assemblies. Quantitative comparisons reveal that neither absorption nor fluorescence spectra of core complexes are simple additive combination...

A π-extended, redox-active bridging ligand 4 ́,5 ́-bis(propylthio)tetrathiafulvenyl[i]dipyrido[2,3-a:3 ́,2 ́-c]phenazine (L) was prepared via direct Schiff-base condensation of the corresponding diamine-tetrathiafulvalene (TTF) precursor with 4,7-phenanthroline-5,6-dione. Reactions of L with [Ru(bpy)2Cl2] afforded its stable monoand dinuclear ruthenium(II) complexes 1 and 2. They have been fully ch...

Cationic lipid-DNA (CL-DNA) complexes comprise a promising new class of synthetic nonviral gene delivery systems. When positively charged, they attach to the anionic cell surface and transfer DNA into the cell cytoplasm. We report a comprehensive x-ray diffraction study of the lamellar CL-DNA self-assemblies as a function of lipid composition and lipid/DNA ratio, aimed at elucidating the intera...

Riboflavin (vitamin B2) is one of the most im­ portant organic redox coenzymes [1 -4], It partic­ ipates in biological electron transfer with redoxactive metalloenzymes. Accordingly, the nature of flavin transition metal complexes is of consider­ able interest [5-16]. If electron transfer between metal and riboflavin takes place in the coordinated state (inner sphere electron transfer) this pro...

Photosynthesis is one of the most essential biological processes in which specialized pigment-protein complexes absorb solar photons, and with a remarkably high efficiency, guide the photo-induced excitation energy toward the reaction center to subsequently trigger its conversion to chemical energy. In this work, we review the principles of optimal energy transfer in various natural and artific...

The various aromatic hydrocarbons (Chart 2) constitute a sharply graded series of sterically encumbered (unhindered, partially hindered, and heavily hindered) donors in electron transfer (ET) to quinones (Chart 1). As such, steric effects provide the quantitative basis to modulate (and differentiate) outer-sphere and inner-sphere pathways provided by matched pairs of hindered and unhindered don...