Charge-transfer mediated J-aggregation in red emitting ultra-small-single-benzenic meta -fluorophore crystals.

Autor: Mandal M; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Mardanya S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Saha A; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Singh M; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Ghosh S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Chatterjee T; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Patra R; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Bhunia S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in.; Centre for Advanced Functional Materials (CAFM), Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246., Mandal S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Mukherjee S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Debnath R; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in., Reddy CM; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in.; Centre for Advanced Functional Materials (CAFM), Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246., Das M; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in.; Centre for Advanced Functional Materials (CAFM), Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246., Mandal PK; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246 prasunchem@iiserkol.ac.in.; Centre for Advanced Functional Materials (CAFM), Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal India-741246.
Jazyk: angličtina
Zdroj: Chemical science [Chem Sci] 2024 Nov 27. Date of Electronic Publication: 2024 Nov 27.
DOI: 10.1039/d4sc06851c
Abstrakt: Red emission in crystals has been observed with an ultra-small-single-benzenic meta -fluorophore ( MF ) with a molecular weight (MW) of only 197 Da, bettering the literature report of fluorophores with the lowest MW = 252 Da. Supramolecular extensive hydrogen-bonding and J-aggregate type centrosymmetric discrete-dimers or a 1D chain of MF s led to red emission ( λ max em = 610-636 nm) in MF crystals. Unlike in the solution phase showing one absorption band, in thin films and in crystals the transition from the S 0 state to both the S 1 - state and S 1 + state becomes feasible. The angle between the transition dipole moments has been obtained to be 66.99° and the exciton splitting energy has been obtained to be (-) 55.7 meV. Significant overlap have been observed and the extent of overlaps integrals between the HOMOs and the LUMOs were assessed to be 0.0068 and (-) 0.00024, respectively. Planar molecules are shown to be involved in anti-parallel stacking with a slip-angle of 44.05° and an inter-planar longitudinal distance of 3.40 Å. A large magnitude of Δ E ES (energy difference between the S 1 - state and S 1 + state) (0.83 eV) has been obtained. A much higher magnitude of the CT coupling constant (-0.708 for MF 2) has been noted in comparison to the coulombic coupling constant (0.016 for MF 2). The excited-state-lifetime has been shown to increase from 5.98 ns (in hexane) to 30.90 ns in the crystal. All these extra-ordinary optical properties point to the existence of a charge-transfer mediated J-aggregation phenomenon in these MF crystals. Based on these fascinating observations, highly stable, bright and colour pure white LEDs could be generated.
Competing Interests: The authors declare no conflict of interest.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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