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RESEARCH PRODUCT

Ethane-Bridged Zinc-Porphyrin Dimers in Langmuir-Shäfer Thin Films: Structural and Spectroscopic Properties

Salvatore SortinoSabrina ConociLivia GiottaSerena CasilliBruno PignataroLudovico ValliYoshihisa InoueVictor V. Borovkov

subject

LangmuirPorphyrinsLangmuir-Schaefer filmPhotochemistryporphyrin dimerPorphyrinSurfaces Coatings and Filmscircular dichroismchemistry.chemical_compoundCrystallographychemistryUltrafast laser spectroscopyMaterials ChemistryArachidic acidFlash photolysisPhysical and Theoretical ChemistryAbsorption (chemistry)Thin filmChiralityUV-vis absorptionConformational isomerismfluorescence and nanosecond laser flash photolysis measurements

description

This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin dimers (1) in Langmuir-Scha¨fer (LS) thin films by combining scanning force microscopy (SFM) with film balance, UV-vis absorption, fluorescence, and nanosecond laser flash photolysis measurements. Results show that depending on the surface pressure the Langmuir films of pure 1 can be arranged in two different condensed phases, whereas SFM of the LS films shows characteristic fractal networks constituted by nanoscopic aggregates. The spectral findings agree with a picture in which 1 is apparently present in the anti conformation but aggregated in a sort of H-type structure whose optical features resemble those of the syn conformer. This type of structure is not responsive to light stimuli. By diluting 1 in arachidic acid the porphyrin aggregation is significantly minimized with 1 exhibiting almost exclusively the anti conformation. As a result the LS films become photoresponsive, showing fluorescence emission and triplet-triplet transient absorption.

yearjournalcountryeditionlanguage
2006-01-01
10.1021/jp054974vhttp://hdl.handle.net/10447/31765