Chlorophyll a Self-assembly in Polar Solvent–Water Mixtures†

Abstract

ABSTRACT

Electrochemical characterization of species involved in photosynthesis: from proteins to model systems

“…The evident relevance of the pigment ability to mutate its physico-chemical properties upon aggregation has induced several laboratories to investigate the conditions at which long-wavelength absorbing forms of chlorophyll can be formed in vitro, in polar and nonpolar solvents and in a series of membrane mimetic systems [14][15][16]. Due to the complexity of the system under investigation and the number of parameters that can influence the Chl a aggregation processes, any study on the equilibrating species in solution may be rather difficult, and needs a large number of techniques to be carried out.…”

Two-Dimensional Electronic Spectroscopy of Chlorophyll a: Solvent Dependent Spectral Evolution

“…Chl a in solution is known to exhibit both self-quenching and the formation of complexes and aggregates, all of which may perturb the electronic spectra. 14 To check for such effects measurements were made in 0.2 mm and 1 mm cells both with an OD of 0.3 at the maximum of the S0 S1 transition, thus varying the concentration by a factor of 5. The main features of the molecular response were independent of concentration confirming that we are studying monomeric Chl a.…”

Aggregates of the Chlorophyll-Binding Protein IsiA (CP43‘) Dissipate Energy in Cyanobacteria

“…The average decay lifetime of the aggregates is then as short as 144 ps. By comparing this number with the decay lifetime of Chl a molecules in acetone of 6.1 ns (44,45), we conclude that IsiA aggregates have an ∼50 times faster average decay lifetime than Chl a in acetone and should therefore have an emission yield of ∼2% compared to that of Chl a in acetone.…”