{
  "abstract": "Regioisomeric engineering provides an effective strategy for controlling excited-state dynamics in donor-acceptor systems, yet its influence on triplet generation and room-temperature phosphorescence (RTP) remains insufficiently understood. Herein, we report two series of carbazole-phenyl-naphthalimide donor-acceptor regioisomers in which carbazole is connected to either the C3 or C4 position of the naphthalimide acceptor through ortho-, meta-, and para-substituted phenyl linkers. Systematic photophysical investigations reveal that subtle changes in molecular connectivity profoundly influence charge-transfer character, fluorescence and intersystem crossing efficiency. Para-linked and C4-substituted derivatives exhibit enhanced fluorescence owing to improved conjugation and reduced structural relaxation, whereas ortho- and meta-isomers as well as C3-substitution promote more efficient triplet generation through spin-orbit charge-transfer-assisted intersystem crossing, yielding triplet quantum yields approaching unity. Femtosecond and nanosecond transient absorption spectroscopy directly elucidate the singlet-to-triplet conversion dynamics, while TD-DFT calculations and single-crystal X-ray diffraction establish clear relationships between molecular geometry, electronic coupling, and excited-state behaviour. Efficient orange-to-red RTP is observed in benzophenone host-guest matrices as well as in water-dispersed nanoaggregates, suggesting that regioisomeric control can activate persistent phosphorescence in both solid-state and colloidal environments. These findings provide valuable molecular design principles for developing purely organic RTP materials for optoelectronics, time-resolved bioimaging, and photonic applications.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Biology and Biotechnology, University of Perugia via Elce di Sotto No. 8 06123 Perugia Italy benedetta.carlotti@unipg.it.",
    "Organic Materials Laboratory, Department of Chemistry, Indian Institute of Technology Roorkee Roorkee 247667 India krjt@cy.iitr.ac.in."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Pietro Mancini"
    },
    {
      "affs": [
        1
      ],
      "name": "Siddan Gouthaman",
      "orcid": "0000-0002-5530-8542"
    },
    {
      "affs": [
        1
      ],
      "name": "Vignesh Rajendran",
      "orcid": "0009-0000-6568-1052"
    },
    {
      "affs": [
        0
      ],
      "name": "Chiara Montanari"
    },
    {
      "affs": [
        0
      ],
      "name": "Valentina Titone"
    },
    {
      "affs": [
        1
      ],
      "name": "K R Justin Thomas",
      "orcid": "0000-0003-2424-5953"
    },
    {
      "affs": [
        0
      ],
      "name": "Benedetta Carlotti",
      "orcid": "0000-0002-2980-2598"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/76kv6h73n6wba.bib",
  "cited_by": 0,
  "doi": "10.1039/d6sc06161c",
  "fulltext_url": "https://europepmc.org/articles/PMC13678590",
  "id": "76kv6h73n6wba",
  "issns": [
    "2041-6520",
    "2041-6539"
  ],
  "landing_url": "https://europepmc.org/article/MED/42899001",
  "language": "eng",
  "licence": "CC-BY-NC",
  "licence_label": "CC BY-NC",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2505|Luminescence and Fluorescent Materials"
    ]
  ],
  "openalex": "W7221829361",
  "pdf_url": "https://europepmc.org/articles/PMC13678590?pdf=render",
  "pmcid": "PMC13678590",
  "pmid": "42899001",
  "published": "2026-10-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/76kv6h73n6wba.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:33Z",
      "native_id": "MED:42899001",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42899001"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:2505|Luminescence and Fluorescent Materials",
      "subfield": "materials-polymers"
    }
  ],
  "title": "Regioisomeric engineering of carbazole-naphthalimide donor-acceptor systems enables efficient triplet generation and room temperature phosphorescence in molecular and nanoaggregated states.",
  "title_text": "Regioisomeric engineering of carbazole-naphthalimide donor-acceptor systems enables efficient triplet generation and room temperature phosphorescence in molecular and nanoaggregated states.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:19:33Z",
  "url": "https://research.draconitic.com/paper/76kv6h73n6wba",
  "venue": "Chemical science",
  "versions": []
}