Absorption coefficients and fluorescence quantum yields of porphyrin films determined by optical and photoacoustic spectroscopies

Ferreira, João F.; Barral, R.; Baptista, João; Ferreira, Miguel

doi:10.1016/0022-2313(91)90144-k

Cited by 12 publications

(6 citation statements)

References 11 publications

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“…In contrast, PtTPBP has a highly distorted saddle-shaped conformation with four orthogonal phenyl rings that reduce the availability of the π-system to intermolecular interactions and electronic delocalization. 37 CuPc shows marked broadening of its low-energy absorption in its thin film spectra, 38,39 while the solution and thin film spectra of PtTPBP are the same line width. 30 Added steric bulk, through appended phenyl rings, decreases the degree of intermolecular interaction for PtTPBP relative to CuPc.…”

Section: Resultsmentioning

confidence: 99%

Molecular and Morphological Influences on the Open Circuit Voltages of Organic Photovoltaic Devices

et al. 2009

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We explore the dependence of the dark current of C(60)-based organic photovoltaic (OPV) cells on molecular composition and the degree of intermolecular interaction of several molecular donor materials. The saturation dark current density, J(S), is an important factor in determining the open circuit voltage, V(oc). The V(oc) values of OPVs show a strong inverse correlation with J(S). Donor materials that show evidence for aggregation in their thin-film absorption spectra and polycrystallinity in thin film X-ray diffraction result in a high dark current, and thus a low V(oc). In contrast, donor materials with structures that hinder intermolecular pi-interaction give amorphous thin films and reduced values of J(S), relative to donors with strong intermolecular pi-interactions, leading to a high V(oc). This work provides guidance for the design of materials and device architectures that maximize OPV cell power conversion efficiency.

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Section: Resultsmentioning

confidence: 99%

Molecular and Morphological Influences on the Open Circuit Voltages of Organic Photovoltaic Devices

et al. 2009

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“…While there are early literature reports on the application of LIOAS and PA spectroscopy to porphyrins related to their fundamental photophysical characterization , the porphyrin, and related tetrapyrrole PAI‐based literature is relatively sparse considering the rich photochemistry for this class of chromophore. The earliest example of a tetrapyrrole study related to PAI, to the best of our knowledge, is a 2002 report by Stolik et al .…”

Section: Molecular Photoacoustic Contrast Agentsmentioning

confidence: 99%

Molecular Photoacoustic Contrast Agents: Design Principles & Applications

Borg

Rochford

2018

Photochem & Photobiology

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Photoacoustic imaging (PAI) is a rapidly growing field which offers high spatial resolution and high contrast for deep-tissue imaging in vivo. PAI is nonionizing and noninvasive and combines the optical resolution of fluorescence imaging with the spatial resolution of ultrasound imaging. In particular, the development of exogenous PA contrast agents has gained significant momentum of late with a vastly expanding complexity of dye materials under investigation ranging from small molecules to macromolecular proteins, polymeric and inorganic nanoparticles. The goal of this review is to survey the current state of the art in molecular photoacoustic contrast agents (MPACs) for applications in biomedical imaging. The fundamental design principles of MPACs are presented and a review of prior reports spanning from early-to-current literature is put forth.

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“…[3b,4] In addition, chemical reagents capable of generating oxidants from O 2 upon photoactivation have been developed for use as photosensitizers in various fields because light is a readily accessible resource. [3a,5] A series of organic molecules, such as riboflavin, rose bengal, methylene blue, and porphyrins, have been used as photoinduced reagents; [3a,5b–h] however, 1) many of them have relatively lower quantum yields than those of photoactivatable transition-metal complexes; [6] and 2) some organic agents are less stable, which potentially indicates their degradation upon irradiation. [5a,i] Photoactivatable metal complexes present relatively high quantum yields, structural stability, and tunable geometries and properties upon ligand substitution.…”

Section: Introductionmentioning

confidence: 99%

An Iridium(III) Complex as a Photoactivatable Tool for Oxidation of Amyloidogenic Peptides with Subsequent Modulation of Peptide Aggregation

Kang

Lee

Nam

et al. 2017

Chemistry A European J

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Aggregates of amyloidogenic peptides are involved in the pathogenesis of several degenerative disorders. Herein, an iridium(III) complex, Ir-1, is reported as a chemical tool for oxidizing amyloidogenic peptides upon photoactivation and subsequently modulating their aggregation pathways. Ir-1 was rationally designed based on multiple characteristics, including 1) photoproperties leading to excitation by low-energy radiation; 2) generation of reactive oxygen species responsible for peptide oxidation upon photoactivation under mild conditions; and 3) relatively easy incorporation of a ligand on the IrIII center for specific interactions with amyloidogenic peptides. Biochemical and biophysical investigations illuminate that the oxidation of representative amyloidogenic peptides (i.e., amyloid-β, α-synuclein, and human islet amyloid polypeptide) is promoted by light-activated Ir-1, which alters the conformations and aggregation pathways of the peptides. Additionally, their potential oxidation sites are identified as methionine, histidine, or tyrosine residues. Overall, our studies on Ir-1 demonstrate the feasibility of devising metal complexes as chemical tools suitable for elucidating the nature of amyloidogenic peptides at the molecular level, as well as controlling their aggregation.

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Absorption coefficients and fluorescence quantum yields of porphyrin films determined by optical and photoacoustic spectroscopies

Cited by 12 publications

References 11 publications

Molecular and Morphological Influences on the Open Circuit Voltages of Organic Photovoltaic Devices

Molecular and Morphological Influences on the Open Circuit Voltages of Organic Photovoltaic Devices

Molecular Photoacoustic Contrast Agents: Design Principles & Applications

An Iridium(III) Complex as a Photoactivatable Tool for Oxidation of Amyloidogenic Peptides with Subsequent Modulation of Peptide Aggregation

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