We report the room temperature phosphorescence upon iodination on a crystalline eumelanin monomer with shielded hydroxyl moieties, ethyl 5,6-dimethoxyindole-2-carboxylate (DMICE). Ultrafast intersystem crossing (ISC) is observed in the iodinated (IDMICE) as well as brominated (BDMICE) analogues of the eumelanin monomer derivative in solution. The triplet quantum yields (φ) and intersystem crossing rates (k) of the halogenated eumelanin derivatives are =25.4±1.1 %; =1.95×10 s and =59.1±1.6 %; 1.36×10 s, as monitored using transient absorption spectroscopy. Theoretical calculations based on nuclear ensemble method reveal that computed k and spin-orbit coupling matrix elements for eumelanin derivatives are larger for IDMICE relative to BDMICE. The halogen and π-π interactions, with distinct excitonic coupling and higher ISC rate promote phosphorescence in IDMICE molecular crystals. Accessing triplet excited states and resultant photoluminescence through structural modification of eumelanin scaffolds paves way for exploring the versatility of eumelanin-inspired molecules as bio-functional materials.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/chem.202400499 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Modulating the γ-ray Protection Properties of Melanin via a Highly Conjugated Catechol Structure.
ACS Biomater Sci Eng
January 2025
Key Laboratory of Radiopharmaceuticals of the Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Melanin is a dark pigment found in many organisms that interacts with various forms of electromagnetic radiation, such as X-rays, γ-rays, and Ultraviolet visible light, providing protection against radiation damage to the host. The mechanism by which melanin protects against ionizing radiation involves dissipating energy around the cell nucleus to form a perinuclear cap. Additionally, melanin reacts with the free radicals produced by the radiolysis of water, quenching reactive oxygen species.
View Article and Find Full Text PDFRoom Temperature Phosphorescence in Crystalline Iodinated Eumelanin Monomer.
Chemistry
May 2024
School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala P.O., Vithura, Thiruvananthapuram, 695551, Kerala, India.
We report the room temperature phosphorescence upon iodination on a crystalline eumelanin monomer with shielded hydroxyl moieties, ethyl 5,6-dimethoxyindole-2-carboxylate (DMICE). Ultrafast intersystem crossing (ISC) is observed in the iodinated (IDMICE) as well as brominated (BDMICE) analogues of the eumelanin monomer derivative in solution. The triplet quantum yields (φ) and intersystem crossing rates (k) of the halogenated eumelanin derivatives are =25.
View Article and Find Full Text PDFDifferences between water-soluble and water-insoluble melanin derived from mushroom.
Food Chem X
December 2022
College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
Melanin is a natural pigment with a high content and a complex polymer structure. In this study, both water-soluble and water-insoluble melanin were obtained from the fruiting bodies of the mushroom , and scanning electron microscopy (SEM), ultraviolet (UV) absorption, Fourier transform infrared (FTIR) spectroscopy, elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, pyrolysis gas chromatography mass spectroscopy (Py-GCMS), and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS/MS) were used to analyze the water-soluble and water-insoluble fungal melanin (IHFM). Differences in the chemical composition and structure of fungal melanin (IHFM) were found.
View Article and Find Full Text PDFImpact of Polydopamine Nanoparticle Surface Pattern and Roughness on Interactions with Poly(ethylene glycol) in Aqueous Solution: A Multiscale Modeling and Simulation Study.
J Phys Chem B
August 2022
Department of Chemical and Biomolecular Engineering, Colburn Laboratory, University of Delaware, 150 Academy Street, Newark, Delaware 19716, United States.
A significant research effort in the past few years has been devoted to engineering synthetic mimics of naturally occurring eumelanin. One such effort has involved the assembly of oligomers of 5,6-dihydroxyindole (DHI), a synthetic precursor of polydopamine (PDA), into melanin-mimicking nanoparticles for use in a variety of applications with desired optical, photonic, thermal, and electrical properties. In many of these applications, the PDA nanoparticles are mixed with other polymers or oligomers, thus motivating this specific study to understand how the surface characteristics of the assembled PDA-nanoparticles affect their interaction with poly(ethylene glycol) (PEG) chains in aqueous solution.
View Article and Find Full Text PDF5,6-Dihydroxyindole eumelanin content in human skin with varying degrees of constitutive pigmentation.
Pigment Cell Melanoma Res
November 2022
Institute for Melanin Chemistry, Fujita Health University, Toyoake, Japan.
Human skin contains two distinct components: brown to black, insoluble eumelanin and light colored, alkaline-soluble pheomelanin. Eumelanin consists of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) moieties, while pheomelanin consists of benzothiazine (BT) and benzothiazole (BZ) moieties. These melanin monomer units can be quantitatively analyzed through specific degradation products by high-performance liquid chromatography (HPLC).
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!