title: Luminescent iron clusters in solution.
abstract: Metal clusters, composed of a few atoms at the core, exhibit unique properties and have potential applications. Although atomically precise clusters of noble metals have been synthesized, analogous systems of reactive metals, such as iron, have not been realized in solution due to high reactivity. Here we report the synthesis and characterization of novel iron clusters in the hemoglobin matrix that are highly luminescent (quantum yield 10% at 565 nm). The super-paramagnetic iron clusters, after successful ligand exchange from protein and phase transfer from water to chloroform using tri-octylphosphineoxide (TOPO), were detected as [Fe₁₀(TOPO)₃(H₂O)₃](+), [Fe₁₃(TOPO)₂(H₂O)](+) and [Fe₈(TOPO)(H₂O)₂](+) by mass spectrometry. This study lays the groundwork for exploiting unique properties of soluble iron clusters.
authors.affiliation: Department of Chemical, Biological & Macromolecular Sciences, Unit for Nanoscience & Technology, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India. skpal@bose.res.in.
authors.forename: Nirmal
authors.initials: N
authors.lastname: Goswami
authors.forename: Ananya
authors.initials: A
authors.lastname: Baksi
authors.forename: Anupam
authors.initials: A
authors.lastname: Giri
authors.forename: Paulrajpillai Lourdu
authors.initials: PL
authors.lastname: Xavier
authors.forename: Gautam
authors.initials: G
authors.lastname: Basu
authors.forename: Thalappil
authors.initials: T
authors.lastname: Pradeep
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Pal
mesh_terms: D002384:Catalysis; D002725:Chloroform / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D013058:Mass Spectrometry; D008670:Metals / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D009943:Organophosphorus Compounds / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D006454:Hemoglobins; D008024:Ligands; D008670:Metals; D009943:Organophosphorus Compounds; D011506:Proteins; D014867:Water; C044965:trioctyl phosphine oxide; D002725:Chloroform; D006861:Hydrogen Peroxide; D007501:Iron