{
  "abstract": "Most quantum sensing experiments require the creation of a spin-optical interface, where optical light can polarize and read out information from spin sublevels. This combination creates a sensor capable of detection down to the single-spin limit. Heteroleptic coordination complexes are promising architectures for enabling positional control of spins in quantum sensing experiments. Towards this end, we use complementary magnetic and optical spectroscopies supported by multiconfigurational electronic structure calculations to establish the first generation of heteroleptic S = 1 Cr4+ complexes as molecular color center candidates. This family of trigonal bipyramidal tris[2-(trimethylsilylamido)ethyl]amine chromium–halide complexes, referenced here as TMStrenCrX (X = F, Cl, Br, and I, respectively known as 1, 2, 3, and 4), exhibits highly modular magnetic and optical properties. 1–4 display largely axial zero-field splitting (ZFS) characterized by high-field, high-frequency continuous-wave electron paramagnetic resonance (HFHF cw-EPR) spectroscopy, where the axial ZFS parameter D continually increases from +5.194(4) cm−1 (1) to +7.34(1) cm−1 (4) as halide donor strength weakens. 1–4 also display near-infrared spin-flip photoluminescence (PL) ranging from 959.57(1) to 1043.81(1) nm. These PL spectra exhibit traits critical for enabling optical addressability, such as optical linewidths narrow enough to rival the magnitude of ZFS. A dilute sample of 4 in its Ti4+ diamagnetic host (4′) even displays optically resolvable spin sublevels under zero applied magnetic field; using variable-field PL spectroscopy, we optically determine its ZFS parameters. These results will lead toward the realization of well-defined spin-analyte interactions and subsequent spatial control of molecular color centers, wherein tunability is maintained through the donor at the axial coordination site.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA",
    "Department of Chemistry, Columbia University New York New York 10027 USA",
    "National High Magnetic Field Laboratory, Florida State University Tallahassee Florida 32310 USA",
    "Department of Chemistry, Northwestern University Evanston Illinois 60208 USA",
    "Pritzker School of Molecular Engineering, University of Chicago Chicago Illinois 60637 USA",
    "Department of Physics, University of Chicago Chicago Illinois 60637 USA",
    "Initiative for Computational Catalysis, Flatiron Institute New York New York 10010 USA"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 13,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Cindy Serena Ngompe Massado",
      "orcid": "0000-0002-3682-5392"
    },
    {
      "affs": [
        0
      ],
      "name": "Rianna B. Greer",
      "orcid": "0000-0002-2289-3749"
    },
    {
      "affs": [
        1
      ],
      "name": "Arailym Kairalapova",
      "orcid": "0000-0002-3337-6026"
    },
    {
      "affs": [
        2
      ],
      "name": "Andrew Ozarowski",
      "orcid": "0000-0001-6225-9796"
    },
    {
      "affs": [
        3
      ],
      "name": "Kelsey A. Collins",
      "orcid": "0000-0002-9202-8179"
    },
    {
      "affs": [
        3
      ],
      "name": "Majed S. Fataftah",
      "orcid": "0000-0002-1742-2854"
    },
    {
      "affs": [
        4
      ],
      "name": "Noah Mendelson"
    },
    {
      "affs": [
        4
      ],
      "name": "Chloe A. Washabaugh",
      "orcid": "0009-0002-9410-3176"
    },
    {
      "affs": [
        3
      ],
      "name": "Daniel W. Laorenza",
      "orcid": "0000-0003-1566-6932"
    },
    {
      "affs": [
        0
      ],
      "name": "Michael K. Wojnar",
      "orcid": "0000-0003-2556-7014"
    },
    {
      "affs": [
        4,
        5
      ],
      "name": "David D. Awschalom",
      "orcid": "0000-0002-8591-2687"
    },
    {
      "affs": [
        1,
        6
      ],
      "name": "Timothy C. Berkelbach",
      "orcid": "0000-0002-7445-2136"
    },
    {
      "affs": [
        0
      ],
      "name": "Danna E. Freedman",
      "orcid": "0000-0002-2579-8835"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cd14w1fpfda72.bib",
  "cited_by": 0,
  "doi": "10.1039/d6sc05602d",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13587845/",
  "id": "cd14w1fpfda72",
  "issns": [
    "2041-6520",
    "2041-6539"
  ],
  "landing_url": "https://doi.org/10.1039/d6sc05602d",
  "language": "en",
  "licence": "CC-BY-3.0",
  "licence_label": "CC BY 3.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/3.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Chemistry"
    ],
    [
      "openalex",
      "2504|Magnetism in coordination complexes"
    ]
  ],
  "openalex": "W7213534383",
  "pdf_url": null,
  "pmcid": "PMC13587845",
  "pmid": "42761563",
  "published": "2026-09-18",
  "publisher": "Royal Society of Chemistry",
  "ris": "https://research.draconitic.com/paper/cd14w1fpfda72.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T12:23:30Z",
      "native_id": "PMC13587845",
      "source": "pmc",
      "url": "https://doi.org/10.1039/d6sc05602d"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:2504|Magnetism in coordination complexes",
      "subfield": "materials-polymers"
    }
  ],
  "title": "Heteroleptic Cr4+ molecular color center candidates",
  "title_text": "Heteroleptic Cr4+ molecular color center candidates",
  "type": "peer-reviewed",
  "updated_at": "2026-11-08T12:20:58Z",
  "url": "https://research.draconitic.com/paper/cd14w1fpfda72",
  "venue": "Chemical Science",
  "versions": []
}