Perylene is a promising annihilator candidate for triplet-triplet annihilation photon upconversion, which has been successfully used in solar cells and in photocatalysis. Perylene can, however, form excimers, reducing the energy conversion efficiency and hindering further development of TTA-UC systems. Alkyl substitution of perylene can suppress excimer formation, but decelerate triplet energy transfer and triplet-triplet annihilation at the same time. Our results show that mono-substitution with small alkyl groups selectively blocks excimer formation without severly compromising the TTA-UC efficiency. The experimental results are complemented by DFT calculations, which demonstrate that excimer formation is suppressed by steric repulsion. The results demonstrate how the chemical structure can be modified to block unwanted intermolecular excited state relaxation pathways with minimal effect on the preferred ones.
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http://dx.doi.org/10.1039/c9cp06561j | DOI Listing |
Sci Total Environ
January 2025
Department of Oncobiology and Epigenetics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland; Laboratory of Transcriptional Regulation, Institute of Medical Biology PAS, Lodz, Poland. Electronic address:
J Phys Chem B
January 2025
Institute for Polymer Research, Waterloo Institute for Nanotechnology, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
The conformation of a series of zero-generation polyamidoamine dendrimers end-labeled with four 1-pyrene-butyroyl, -hexanoyl, -octanoyl, -decanoyl, and -dodecanoyl derivatives, referred to as the PyCX-PAMAM-G0 samples with = 4, 6, 8, 10, and 12, respectively, was characterized in ,-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and aqueous solutions of 50 mM sodium dodecyl sulfate (SDS) or 50 mM dodecyltrimethylammonium bromide (DTAB). The conformation of the PyCX-PAMAM-G0 samples was determined from the global model-free analysis (MFA) of the fluorescence decays, which yielded the average rate constant (⟨⟩) for pyrene excimer formation (PEF) between an excited and a ground-state pyrenyl labels, with ⟨⟩ being proportional to the local concentration ([Py]) of the pyrenyl labels within the macromolecular volume; ⟨⟩-vs-[Py] plots yielded straight lines passing through the origin in DMF and DMSO, demonstrating that the internal segments of the dendrimers obeyed Gaussian statistics in these two solvents. In aqueous surfactant solutions, the hydrophobic pyrenyl labels induced the interactions of the PyCX-PAMAM-G0 dendrimers with the SDS and DTAB micelles.
View Article and Find Full Text PDFTalanta
January 2025
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, PR China. Electronic address:
As an important biological indicator, the abnormity of the lysozyme level is closely related to many diseases. Herein, we devise a novel ratiometric fluorescence aptasensor for lysozyme based on the controllable excimer formation of a perylene probe, N, N'-bis(6-caproic acid)-3,4:9,10-perylene diimide (PDI) induced by cationic silver nanoparticles (Ag NPs). Binding of lysozyme aptamer with multiple phosphate groups to cationic Ag NPs strongly hinders the formation of excimer, yielding intense monomer fluorescence of PDI probe.
View Article and Find Full Text PDFLangmuir
January 2025
Department of Chemistry, National Institute of Technology, Rourkela, Odisha 769008, India.
Bile salts (BS) are naturally occurring steroidal biosurfactants. The ease of functionalization of BSs has boosted their use as inexpensive building blocks for the fabrication of a broad set of value-added soft functional materials. In the present work, three fluorescent bile acid (FBA) derivatives have been synthesized by conjugating anthracene at the side chain of lithocholic acid, deoxycholic acid, and cholic acid to understand the effect of the nature of the steroid nucleus on their physicochemical properties.
View Article and Find Full Text PDFProg Retin Eye Res
January 2025
ELZA Institute, Webereistrasse 2, CH-8953, Dietikon, Switzerland; Laboratory for Ocular Cell Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland; Faculty of Medicine, University of Geneva, Rue Michel-Servet 1, CH-1206, Geneva, Switzerland. Electronic address:
First introduced over 20 years ago as a treatment for progressive keratoconus, the original "Dresden" corneal cross-linking (CXL) protocol involved riboflavin saturation of the stroma, followed by 30 min of 3 mW/cm-intensity ultraviolet-A (UV-A) irradiation. This procedure generates reactive oxygen species (ROS) that cross-link stromal molecules, thereby stiffening the cornea and counteracting the ectasia-induced weakening. Due to their large size, riboflavin molecules cannot readily pass through the corneal epithelial cell tight junctions; thus, epithelial debridement was performed.
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