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Research was conducted to investigate the site-to-site intramolecular excitation transfer and excitation trapping on one site in amino-substituted triphenylbenzene derivatives characterized by a 3-fold symmetry. Methods used were time-resolved microwave conductivity and fluorescence spectroscopy. Results demonstrate the significance of dipole relaxation due to intramolecular energy transfer in the interpretation of the change of the polarizability and dipole moment upon excitation and the limiting anisotropy.

The supramolecular organization of a new polychlorotriphenyl (PTM) radical bearing three long alkyl chains is analyzed by scanning tunneling microscopy (STM) at the liquid-solid interface. The radical has self-assembled hierarchically on graphite forming head-to-head dimers that is organized in rows following a spin-containing two-leg molecular ladder topology, in which the alkyl chains have determined the space between the radical rows and have acted as diamagnetic barriers.

Thermal treatment of [Ag.sup.+]-exchanged zeolites has produced discrete highly photostable luminescent clusters without the formation of metallic nanoparticles. Different types of emitters with characteristic luminescence colors are seen, which has depended on the nature of the cocation, the amount of exchanged silver, and the host topology.

The second-order nonlinear optical properties of green fluorescent proteins (GFPs) like the photoswitchable Dronpa and enhanced GFP (EGFP) are studied. The second-order nonlinear optical properties of GFP-like proteins are important for the combined nonlinear microscopy based on existing fusion proteins involving GFPs.

We use single-molecule fluorescence lifetimes to probe dynamics of photoinduced reversible electron transfer occurring between triphenylamine (donor) and perylenedilmide (acceptor) in single molecules of a polyphenylenic rigid dendrimer embedded in polystyrene. Here, reversible electron transfer in individual donor-acceptor molecules results in delayed fluorescence that is emitted with a high photon count rate. By monitoring fluorescence decay times on a photon-byephoton basis, we find fluctuations in both forward and reverse electron transfer spanning a broad time range, from milliseconds to seconds. Fluctuations are induced by conformational changes in the dendrimer structure as well by polystyrene chain reorientation. The conformational changes are related to changes in the dihedral angle of adjacent phenyl rings located in the dendritic branch near the donor transferring the charge, a torsional motion that results in millisecond fluctuations in the "through-bond" donor-acceptor electronic coupling. Polymer chain reorientation leads to changes in the local polarity experienced by the donors and to changes in the solvation of the charge-separated state. As a result switching between different donor moieties within the same single molecule becomes possible and induces fluctuations in decay time on a time scale of seconds. [ABSTRACT FROM AUTHOR]