title: Heteroleptic dipyrrinato complexes containing 5-ferrocenyldipyrromethene and dithiocarbamates as coligands: selective chromogenic and redox probes.
abstract: Six heteroleptic dipyrrinato complexes [Ni(fcdpm)(dedtc)] (1), [Ni(fcdpm)(dipdtc)] (2), [Ni(fcdpm)(dbdtc)] (3), [Pd(fcdpm)(dedtc)] (4), [Pd(fcdpm)(dipdtc)] (5), and [Pd(fcdpm)(dbdtc)] (6) (fcdpm = 5-ferrocenyldipyrromethene; dedtc = diethyldithiocarbamate; dipdtc = diisopropyldithiocarbamate; dbdtc = dibutyldithiocarbamate) have been synthesized and characterized by elemental analyses and spectral (ESI-MS, IR, (1)H, (13)C NMR, UV-vis) and electrochemical studies. Crystal structures of 1, 2, 4, and 5 have been authenticated by X-ray single-crystal analyses. Nickel-based complexes 1-3 display selective chromogenic and redox sensing for Hg(2+) and Pb(2+) ions, while palladium complexes 4-6 display selective chromogenic and redox sensing only for Hg(2+). Electronic absorption, ESI-MS, and electrochemical studies indicated that sensing arises from interaction between 1-3 and Hg(2+)/Pb(2+) through sulfur of the coordinated dithiocarbamates, while it arises from the pyrrolic nitrogen of fcdpm and dithiocarbamate sulfur from 4-6 and Hg(2+). Different modes of binding between Ni and Pd complexes have further been supported by theoretical studies. The receptor-cation binding constants (K(a)) and stoichiometry between probes and Hg(2+)/Pb(2+) have been estimated by the Benesi-Hildebrand method and Job's plot analysis. Detection limits for 1-3 toward Hg(2+)/Pb(2+) and 4-6 for Hg(2+) have been found to be reasonably high.
authors.affiliation: Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221 005 (U.P.), India.
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Gupta
authors.forename: Rampal
authors.initials: R
authors.lastname: Pandey
authors.forename: Roopshikha
authors.initials: R
authors.lastname: Singh
authors.forename: Nitin
authors.initials: N
authors.lastname: Srivastava
authors.forename: Biswajit
authors.initials: B
authors.lastname: Maiti
authors.forename: Satyen
authors.initials: S
authors.lastname: Saha
authors.forename: Peizhou
authors.initials: P
authors.lastname: Li
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.forename: Daya Shankar
authors.initials: DS
authors.lastname: Pandey
mesh_terms: D002413:Cations, Divalent; D056831:Coordination Complexes / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D005296:Ferrous Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D007700:Kinetics; D007854:Lead / Q000032:analysis; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008628:Mercury / Q000032:analysis; D015335:Molecular Probes / Q000138:chemical synthesis*; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D013859:Thiocarbamates / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D056831:Coordination Complexes; D005296:Ferrous Compounds; D005456:Fluorescent Dyes; D008024:Ligands; D015335:Molecular Probes; D013859:Thiocarbamates; D007854:Lead; D010165:Palladium; D009532:Nickel; D008628:Mercury