Spectroscopic studies of phthalocyanine monolayers

Burack, J.J.; LeGrange, J. D.; Markham, Julie L.; Rockward, W.

doi:10.1021/la00038a052

Cited by 14 publications

(5 citation statements)

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“…PcCp 4 isotherms without alcohol gave MMA's ranging from about 55 to 80 Å 2 . Although this value differs significantly from the literature for copper centered PcCp 4 (Barger et al and Suzuki et al measured MMA's of approximately 35 Å 2 ), this result indicates that the phthalocyanine associations without transfer promoter are very sensitive to external conditions such as solution concentration, rate of compression, temperature, and the absence of a copper center . Mixed films (alcohol:PcCp 4 ) produced very reproducible isothermsoften the isotherms of alcohol to PcCp 4 ratios greater than 2:1 superimpose exactly and were rarely different by more than 2%.…”

Section: Methodscontrasting

confidence: 68%

“…The tetrakis(cumylphenoxy) derivative of the phthalocyanine [PcCp 4 ] with octadecanol as the transfer promoter has been used in films extensively as chemiresistors and has been widely examined. It has been suggested that the cumylphenoxy side groups increase the phthalocyanine's solubility in polar solvents and provide better adhesion to hydrophilic solid substrates . Barger et al demonstrated the need for the transfer promoter for a series of ether linked substituents on the Pc ring and were the first to suggest that the rings were not flat on the surface.…”

Section: Introductionmentioning

confidence: 99%

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Alcohol Chain Length and Mole Fraction Dependence of the Stability of Tetrakis(cumylphenoxy)phthalocyanine and Alcohol Langmuir Films

et al. 1998

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While it has been known for about 10 years that octadecanol stabilizes Langmuir−Blodgett films of copper tetrakis(cumylphenoxy)phthalocyanine films, the mechanism for this stabilization is not fully understood. To understand more completely the molecular interactions responsible for making octadecanol a good transfer promoter, we studied mixed films' isotherms of tetrakis(cumylphenoxy)phthalocyanine and various saturated alcohols ranging in length from 13 to 24 carbons. By varying mole fraction and alcohol chain length in the various mixed films, a model of interaction was deduced based on pressure-versus-area isotherms obtained from a Langmuir trough. In this model, the aliphatic chains of the alcohols act as a stabilizing, hydrophobic support around phthalocyanine mounds of a preferred stack height. As film pressure increases, the mounds are forced above the alcohol sea, removing favorable ether−water interactions. Depending on chain length, a single or double collapse is observed, suggesting an adjustable physical barrier to forcing the stacks above the alcohols.

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Section: Methodscontrasting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Alcohol Chain Length and Mole Fraction Dependence of the Stability of Tetrakis(cumylphenoxy)phthalocyanine and Alcohol Langmuir Films

et al. 1998

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“…The Q-band of Pc becomes broader after the attachment to the gold nanoparticles (Figure A). The broadening of the Q-band can be attributed to aggregation of the phthalocyanine molecules , in the Pc-AuNP. Phthalocyanines usually form face-to-face-oriented H-aggregates, which are characterized by blueshifted absorption bands, but side-by-side-oriented J-aggregates are also possible .…”

Section: Resultsmentioning

confidence: 99%

Photoinduced Charge and Energy Transfer in Phthalocyanine-Functionalized Gold Nanoparticles

et al. 2009

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Photoinduced processes in phthalocyanine-functionalized gold nanoparticles (Pc-AuNPs) have been investigated by spectroscopic measurements. The metal-free phthalocyanines used have two linkers with thioacetate groups for bonding to the gold nanoparticle surface, and the attachment was achieved using a ligand exchange reaction. The absorption spectrum of the Pc-AuNPs shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, fluorescence is strongly quenched, and the fluorescence lifetimes determined by time-correlated single photon counting (TCSPC) are strongly reduced. The quenching mechanisms were studied in detail with time-resolved absorption (pump−probe) measurements. A selective excitation of the gold cores in the pump−probe experiment results in an energy transfer from the gold nanoparticles to the attached phthalocyanines in ∼2.4 ps. Photoexcitation of mainly the phthalocyanines in the functionalized nanoparticles leads to an electron transfer to the gold core in ∼3.0 ps. The recombination of charges in the Pc-AuNP takes place on a picosecond time scale. In addition, there is evidence of energy transfer from the photoexcited phthalocyanines to the gold nanoparticles.

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“…Of these, the LB technique is most effective in controlling thickness and structure on a molecular level . Hence, the LB films of Pc derivatives substituted at the periphery of their structure with various bulky alkyl and/or alkoxy groups, including tert -butyl, 3a,− 9b hexyl,3b octyl, decyl, 3b, dodecyl, methoxy, butoxy, , octyloxy, ,14b benzyloxyethoxy, decyloxy, or cumylphenoxy, 3b,,, have been prepared and characterized in detail because of their good amphiphilic character.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic and Electrochemical Characterizations of Dilithium Octacyanophthalocyanine Langmuir−Blodgett Films

et al. 2002

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Langmuir−Blodgett (LB) films of dilithium octacyanophthalocyanine [Li2Pc(CN)8] were first prepared, and their electrochemical reduction/reoxidation behaviors were studied in detail. An overwhelming majority of the Li2Pc(CN)8 molecules in the LB film were stacked in a face-to-face aggregated state and stood obliquely with an edge-on configuration on the substrate surface. Two overlapping redox waves were observed in the voltammogram of the LB film in 1 mol dm-3 HCl solution. Their relative intensity was found to be largely dependent on the molecular aggregation state in the film. On the basis of spectroscopic and electrochemical analyses, the first and second reduction waves upon cathodic potential scanning were principally assigned to the aggregated and monomeric Li2Pc(CN)8 molecules, respectively, in the solid film structure. In comparison with the corresponding solvent-cast film, charge transfer within the LB film and/or through the electrode interface was facilitated, and the LB film showed excellent dynamic character in the redox process.

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Spectroscopic studies of phthalocyanine monolayers

Cited by 14 publications

References 0 publications

Alcohol Chain Length and Mole Fraction Dependence of the Stability of Tetrakis(cumylphenoxy)phthalocyanine and Alcohol Langmuir Films

Alcohol Chain Length and Mole Fraction Dependence of the Stability of Tetrakis(cumylphenoxy)phthalocyanine and Alcohol Langmuir Films

Photoinduced Charge and Energy Transfer in Phthalocyanine-Functionalized Gold Nanoparticles

Spectroscopic and Electrochemical Characterizations of Dilithium Octacyanophthalocyanine Langmuir−Blodgett Films

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