Langmuir-Blodgett Films of Amphiphilic Push-Pull Porphyrins
作者:Homer Chou、Chin-Ti Chen、Kurt F. Stork、Paul W. Bohn、Kenneth S. Suslick
DOI:10.1021/j100053a003
日期:1994.1
A series of nitrophenyl-amidophenyl-substituted porphyrins with n-C17H35 tails have been synthesized and fully characterized. Good Langmuir-Blodgett films of these materials can be prepared on water and transferred successfully to glass slides. Mean molecular areas for the series were measured and found to increase from 80 to 230 Angstrom(2) as the number of aliphatic chains increased from one to four. As determined by linear dichroic measurements, this change in area does not correspond to a change in the orientation of the porphyrin with respect to the surface. In the absence of the steric constraints of multiple aliphatic chains, porphyrin-porphyrin stacking permits close packing of the rings. As the number of aliphatic chains on the porphyrin periphery increases, however, the porphyrin planes must pack more loosely. Thus, the porphyrin macrocycle orientation is determined by interactions between porphyrin rings and between porphyrins and the aqueous (or polar glass) surface. In contrast, the differences in the observed mean molecular area are determined independently by packing constraints imposed by the pendant hydrocarbon chains.
Synthesis and Characterization of Push-Pull Porphyrins
作者:Chin-Ti Chen、Shih Jung Hsieh
DOI:10.1002/jccs.199700005
日期:1997.2
AbstractA series of “push‐pull” porphyrins with 4‐nitrophenyl and 4‐aminophenyl substituents were synthesized and separated by flash column chromatographic techniques. They were fully characterized by elemental analysis, FAB‐MS, FTIR, UV‐visible, and 1H NMR spectroscopies. The unsymmetrical π‐electron distribution of the porphyrins caused by the donor (amino) and acceptor (nitro) substituents were investigated by 1H NMR technique. The pyrrole‐H resonance positions can be correlated to the Hammett σ constants of the substituents. Although with strong donor and acceptor substituents, UV‐visible spectra show the push‐pull porphyrins have rather weak solvatochromism and hence limited intramolecular charge‐transfer character.