Effect of the External Refractive Index on Fluorescence Kinetics of Perylene in Human Erythrocyte Ghosts

Fluorescence kinetics of perylene molecules in hemoglobin-free human erythrocyte membranes is investigated as a function of the refractive index of the external medium varied by adjusting the concentration of sorbitol or sucrose in an aqueous suspension of erythrocyte ghosts. It has been found that the fluorescence of perylene in erythrocyte ghosts decays nonexponentially, with the mean decay time decreasing from 7.13 to 5.70 ns with an increase in the refractive index of the suspension from 1.333 to 1.442. An analysis of the dependence made it possible to obtain an estimate of the second-rank orientational order parameter of perylene in the human erythrocyte membrane «P ₂ (cos)» = 0.32 ... 0.43, which bears witness of considerable ordering of perylene molecules along acyl chains of phospholipids constituting the membrane. Good correspondence of the order parameter with the value of the steady-state emission anisoptropy of perylene in erythrocyte ghosts suggests that acyl chains of phospholipids in the human erythrocyte membrane are predominantly oriented along the normal to its surface.     

Electrochemical and optical properties of novel donor‐acceptor thiophene‐perylene‐thiophene polymers

In this study, donor‐acceptor type thiophene‐perylene‐thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl₃ as catalyst and the electrochemical process. UV–vis, FTIR, ¹H NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV–vis measurements, respectively. The number–average molecular weight (M_n), weight–average molecular weight (M_w), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four‐point probe technique. The conductivity was observed to be increased by iodine doping. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1974–1989, 2008     

Characterization of a Series of Far Red Absorbing Perylene Diones: A New Class of Fluorescent Probes for Biological Applications

The far red region of the spectrum is increasingly being utilised in many applications in the biosciences. However, apart from the cyanine group of dyes, there are relatively few far red fluorescent probes available which are of practical use. We have synthesised and characterised a new class of far red fluorescent probes based on the perylene dione chromophore. The 2,10 di-substituted perylene diones possess broad absorption spectra (>90 nm bandwidths), large Stokes shifts (>60 nm) and quantum yields of up to 0.5 with a maximum absorption at 610–640 nm in organic solvents or in solutions of non-ionic detergents. A number of derivatives have been synthesised that can be used as membrane probes, as chromogenic substrates for alkaline phosphatase, and for the labelling of macromolecules such as proteins and DNA. These novel far red fluorophores have potential applications in diagnostic and research applications.     

Effect of crystalline microstructure on the photophysical performance of polymer／perylene composite films

To obtain high carrier mobility, better charge injection capability, and high photovoltaic device conversion efficiency, a powerful strategy is to improve the morphology of the polymer/dye composite films. Conjugated conducting polymer (CP) thin films doped with perylene derivative (PV) of various concentrations were prepared by spin-casting method, and their morphology and photovoltaic characteristics were examined. The change in morphology and molecular reorientation occurring in CP-PV composite films upon annealing at different temperatures was investigated using scanning electron microscopy, x-ray diffraction, Fourier transform infrared and UV-vis absorption. By changing the annealing temperature, PV microcrystallines of 8－10μm in size lying parallel to the substrate surface can be obtained. Annealing effect improved the photovoltaic performance of ITO/CP-PV/Al Schottky-type solar cells, which can be attributed to the formation of an electron conducting PV crystal network. Preliminary studies indicate that the morphological structure in CP-PV composite films has an important influence to their photovoltaic properties.     

Photosensitizing Antivirals

Antiviral action of various photosensitizers is already summarized in several comprehensive reviews, and various mechanisms have been proposed for it. However, a critical consideration of the matter of the area is complicated, since the exact mechanisms are very difficult to explore and clarify, and most publications are of an empirical and “phenomenological” nature, reporting a dependence of the antiviral action on illumination, or a correlation of activity with the photophysical properties of the substances. Of particular interest is substance-assisted photogeneration of highly reactive singlet oxygen (¹O₂). The damaging action of ¹O₂ on the lipids of the viral envelope can probably lead to a loss of the ability of the lipid bilayer of enveloped viruses to fuse with the lipid membrane of the host cell. Thus, lipid bilayer-affine ¹O₂ photosensitizers have prospects as broad-spectrum antivirals against enveloped viruses. In this short review, we want to point out the main types of antiviral photosensitizers with potential affinity to the lipid bilayer and summarize the data on new compounds over the past three years. Further understanding of the data in the field will spur a targeted search for substances with antiviral activity against enveloped viruses among photosensitizers able to bind to the lipid membranes.     

Perylene Diimide Hexamer Based on Combination of Direct and Indirect Linkage Manners for Non-fullerene Organic Solar Cells

Perylene diimide (PDI) is one of the most intensively studied building blocks for the construction of non-fullerene acceptors (NFAs). In this contribution, based on combination of the direct and indirect linkage manners of PDI units at the bay position, a propeller-shaped PDI hexamer T-DPDI was designed and synthesized. The singly bonded PDI dimer DPDI and the benzene ring cored PDI trimer TPDI were synthesized for comparison. The photovoltaic performances of these three PDI derivatives were investigated using the commercially available PTB7-Th as electron donor. A best power conversion efficiency (PCE) of 6.58% was obtained for T-DPDI based organic solar cells (OSCs), which is higher than those of DPDI and TPDI based ones. The superior photovoltaic performance of T-DPDI can be ascribed to its stronger absorption and more favorable morphology. This study presents an interesting example of improving the photovoltaic performances of PDI based NFAs by hybridizing the direct and indirect linkage manners.     

Macrocyclic Donor-Acceptor Dyads Composed of Oligothiophene Half-Cycles and Perylene Bisimides

A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.     

Smart Shell-by-Shell Nanoparticles with Tunable Perylene Fluorescence in the Organic Interlayer

A new series of shell-by-shell (SbS)-functionalized Al₂O₃ nanoparticles (NPs) containing a perylene core in the organic interlayer as a fluorescence marker is introduced. Initially, the NPs were functionalized with both, a fluorescent perylene phosphonic acid derivative, together with the lipophilic hexadecylphosphonic acid or the fluorophilic (1 H,1 H,2 H,2H-perfluorodecyl)phosphonic acid. The lipophilic first-shell functionalized NPs were further implemented with amphiphiles built of aliphatic chains and polar head-groups. However, the fluorophilic NPs were combined with amphiphiles consisting of fluorocarbon tails and polar head-groups. Depending on the nature of the combined phosphonic acids and the amphiphiles, tuning of the perylene fluorescence can be accomplished due variations of supramolecular organization with the shell interface. Because the SbS-functionalized NPs dispose excellent dispersibility in water and in biological media, two sorts of NPs with different surface properties were tested with respect to biological fluorescent imaging applications. Depending on the agglomeration of the NPs, the cellular uptake differs. The uptake of larger agglomerates is facilitated by endocytosis, whereas individualized NPs cross directly the cellular membrane. Also, the larger agglomerates were preferentially incorporated by all tested cells.