Spectroscopic and Photophysical Characterization of Acetylenic Fluorophores: The Role of the Proximity Effect on Increasing Internal Conversion.

The spectroscopic and photophysical behavior of a series of six extended arylacetylenes and one 1,3-diyne derivative was studied in solvents of different polarity to gain insight into the relationships between molecular architecture and optical/photophysical properties. The radiative decay channel was revealed to be the most important one for all the compounds, particularly in nonpolar solvents. A notable fluoro-solvatochromism was observed for the 1,3-diyne derivative in line with the large increase of its dipole moment under excitation.

Quantitative cascade energy transfer in semiconductor thin films.

In this contribution we report the photophysical study of three organic blend systems comprising [60]PCBM along with different combinations of five extended semiconducting arylacetylenes, i.e. p-[(2-{[m,p-didodecyloxyphenyl]ethynyl}-7-fluorenyl)ethynyl]benzonitrile, 4,7-bis(5-{[m,p-bis(hexyloxy)phenyl]ethynyl}thien-2-yl)-2,1,3-benzothiadiazole, 9,10-bis-[(m,m-bis{[m,m-bis-(hexyloxy)phenyl]ethynyl}phenyl)ethynyl]-anthracene, pseudo-p-[(10-{[m,p-bis-(hexyloxy)phenyl]ethynyl}-9-anthryl[2.

Comprehensive photophysical behaviour of ethynyl fluorenes and ethynyl anthracenes investigated by fast and ultrafast time-resolved spectroscopy.

Detailed investigations by time-resolved transient absorption and fluorescence spectroscopies with nano- and femtosecond time resolutions are carried out with the aim of characterising the lowest excited singlet and triplet states of three ethynyl fluorenes (1-3) and three ethynyl anthracenes (4-6) in solvents of different polarity. The solvent is found to modify the deactivation pathways of the lowest excited singlet state of compounds 1-4, thus changing their fluorescence, intersystem crossing and internal conversion efficiencies. The fluorescence and triplet yields gradually decrease, while the internal conversion quantum yield increases upon increasing the solvent dielectric constant.

Recovery of CdS nanocrystal defects through conjugation with proteins.

The luminescence behavior of CdS nanocrystals in aqueous solution and in the presence of proteins has been deeply investigated. CdS nanocrystals have been prepared in water by thermal decomposition of a single organometallic precursor assisted by thioglycerol, which acts as capping agent. Different experimental conditions have been explored to gain insights into the parameters affecting the nanocrystal growth.