Nanoscale visualization of microcrystalline chlorophyll a investigated with scanning tunneling microscopy

Chlorophylls in thin-film photovoltaic cells, a critical review

Self-assembly and electrical properties of chlorophyll-type dyes are reviewed with emphasis on their potential applications in thin-film solar cells.

The effects of halogen bonding and molecular design on the self-assembly of coordination polymers of Mn(iii)-tetraarylporphyrin with axial bridging ligands

Two new coordination polymers of Mn(iii)-tetra(iodophenyl)porphyrin with isonicotinate and pyrimidine-5-carboxylate linkers have been synthesized. The effect of halogen-bonding interactions on their self-assembly in the crystalline bulk and on a graphite surface has been discussed.

Study of the Conformational Changes of Chlorophyll a (Chl a) Colloids with the Atomic Force Microscope

Atomic force microscopic (AFM) images of chlorophyll a (Chl a) colloids deposited onto mica and Au(111) present two different shapes. The colloids appear as clouds on mica and as large chains on Au(111). This difference in topography is attributed to different interactions between the colloids and the substrate. The real-time changes occurring during the electrodeposition of the colloids are also monitored. For an applied electric field intensity varying between 5 x 10(3) and 25 x 10(4) V/m, the colloids are opened and flattened relative to a deposition in the absence of an electric field and the drop method. However, when these films are exposed to ethanol vapors, disaggregation occurrs. These changes indicate that the association of Chl a dimers can form nanocrystals with large size distribution: 45-100 nm. Arrangement of nanocrystals in colloids is a characteristic feature of microcrystalline Chl a. The interaction between the colloids and H2O can also provoke aggregate dissociation. Copyright 1999 Academic Press.

Chlorophyll a dimer: a possible primary electron donor for the photosystem II

In the photosynthetic membrane, there is a particular aggregated state for the chlorophyll a (Chl a) molecules with a specific arrangement responsible for the high efficiency of energy conversion. Chl a monolayers, transferred onto solid substrates, are systems that potentially can mimic the packing of the in vivo system. The association of Chl a in the monolayer results in the formation of dimers with an average size of 3.00 +/- 0.15 nm. Considering the organization of the dimers, we assume that P680 is a dimer with the (anti) parallel transition moments of the constituent. The Chl a macrocycles most likely are tilted to each other by 30 degrees with respect to the membrane plane.