{
  "abstract": "The development of portable, cost-effective, and practical analytical platforms for rapid on-site detection of Cu²⁺ remains challenging. Herein, we have reported the novel one-pot synthesis of an indole-based sensor for Cu²⁺, namely (E)-N'-((1H-indol-3-yl)methylene)picolinohydrazide (MPH), which was characterized by FT-IR, ¹H-NMR, ¹³C-NMR, elemental analysis, HRMS, and single-crystal X-ray diffraction. The sensing performance of MPH toward various metal ions was evaluated using colorimetric analysis, UV-vis spectroscopy, cyclic voltammetry, and a smartphone-assisted RGB platform in MeOH/H₂O. MPH exhibited high selectivity for Cu²⁺ ions, producing a distinct color change from colorless to intense yellow (≤1 second). Job's plot analysis revealed the formation of a 2 : 1 (MPH : Cu²⁺) complex. The titration studies revealed a distinct isosbestic point at 308 nm, indicating a clean and well-defined interconversion between the free and complexed species. The binding mechanism was investigated using FT-IR, ¹H NMR, ESI-MS, FESEM, and was supported by DFT calculations. The UV-vis method achieved a Cu²⁺ detection limit of 4.48 × 10⁻⁶ M, surpassing EPA drinking water standards. The sensor also demonstrated excellent reversibility and recyclability with EDTA, while the RGB platform enabled real-time Cu²⁺ quantification with a detection limit of 5.5 × 10⁻⁶ M. Practical applicability was confirmed through logic-gate operations, paper strip method, antimicrobial studies, and Cu²⁺ determination in real environmental samples. These ultrafast responses, high sensitivity, multifunctional capabilities, reusability, and real-world applicability suggest MPH as a highly effective, economical, and field-ready sensor for practical Cu²⁺ monitoring in environmental and analytical conditions.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Jashore University of Science and Technology Jashore 7408 Bangladesh joardargim@gmail.com debnathdipa018@gmail.com redikaprity@gmail.com tasnim.b920@gmail.com m.azizurrahman.khan@just.edu.bd zannatulkowser_che@just.edu.bd.",
    "Department of Chemical Engineering, Jashore University of Science and Technology Jashore 7408 Bangladesh mr.amin.just@gmail.com.",
    "Department of Pharmacy, Jashore University of Science and Technology Jashore 7408 Bangladesh sadmanp100@gmail.com kmazumder@just.edu.bd.",
    "Faculty of Science, Agriculture & Engineering, Newcastle University Newcastle upon Tyne NE1 7RU UK paul.waddell@ncl.ac.uk.",
    "Department of Environmental Science and Technology, Jashore University of Science and Technology Jashore 7408 Bangladesh ribbas_est@just.edu.bd.",
    "Department of Applied Chemistry, Faculty of Science and Engineering, Saga University Honjo-machi 1 Saga 840-8502 Japan yamatot@cc.saga-u.ac.jp."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 12,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Joardar Gim",
      "orcid": "0009-0009-6332-3978"
    },
    {
      "affs": [
        0
      ],
      "name": "Dipa Debnath"
    },
    {
      "affs": [
        0
      ],
      "name": "Redika Sarmin Prieety"
    },
    {
      "affs": [
        0
      ],
      "name": "Miss Tasnim Jahan"
    },
    {
      "affs": [
        1
      ],
      "name": "Md Ruhul Amin"
    },
    {
      "affs": [
        2
      ],
      "name": "Md Sadman Hossain"
    },
    {
      "affs": [
        3
      ],
      "name": "Paul G Waddell",
      "orcid": "0000-0002-7851-7347"
    },
    {
      "affs": [
        2
      ],
      "name": "Kishor Mazumder",
      "orcid": "0000-0002-8711-7409"
    },
    {
      "affs": [
        4
      ],
      "name": "Md Sabbir Hossain",
      "orcid": "0009-0003-2904-017X"
    },
    {
      "affs": [
        0
      ],
      "name": "M Azizur R Khan",
      "orcid": "0009-0001-8813-1683"
    },
    {
      "affs": [
        5
      ],
      "name": "Takehiko Yamato",
      "orcid": "0000-0002-8812-2242"
    },
    {
      "affs": [
        0
      ],
      "name": "Zannatul Kowser",
      "orcid": "0009-0001-5658-7045"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/evw5ngxv8gqdh.bib",
  "cited_by": 0,
  "doi": "10.1039/d6ra07863j",
  "fulltext_url": "https://europepmc.org/articles/PMC13712236",
  "id": "evw5ngxv8gqdh",
  "issns": [
    "2046-2069"
  ],
  "landing_url": "https://europepmc.org/article/MED/42948676",
  "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": [
    [
      "heading",
      "Chemistry"
    ],
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      "openalex",
      "1607|Molecular Sensors and Ion Detection"
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  "openalex": "W7223996431",
  "pdf_url": "https://europepmc.org/articles/PMC13712236?pdf=render",
  "pmcid": "PMC13712236",
  "pmid": "42948676",
  "published": "2026-10-27",
  "publisher": "Royal Society of Chemistry",
  "ris": "https://research.draconitic.com/paper/evw5ngxv8gqdh.ris",
  "sources": [
    {
      "first_seen": "2026-10-31T00:20:33Z",
      "native_id": "MED:42948676",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42948676"
    },
    {
      "first_seen": "2026-10-31T12:22:51Z",
      "native_id": "PMC13712236",
      "source": "pmc",
      "url": "https://doi.org/10.1039/d6ra07863j"
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  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1607|Molecular Sensors and Ion Detection",
      "subfield": "physical"
    }
  ],
  "title": "A reversible indole-based colorimetric chemosensor for Cu²⁺: implications for smartphone-integrated sensing, logic gate experiments, environmental and biological applications.",
  "title_text": "A reversible indole-based colorimetric chemosensor for Cu²⁺: implications for smartphone-integrated sensing, logic gate experiments, environmental and biological applications.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T12:22:51Z",
  "url": "https://research.draconitic.com/paper/evw5ngxv8gqdh",
  "venue": "RSC advances",
  "versions": []
}