title: A Ni-based MOF for selective detection and removal of Hg2+in aqueous medium: a facile strategy.
abstract: The uncoordinated sulfur atom of the thiocyanato ligand of a 3D metallo-organic framework (MOF), [Ni(3-bpd)2(NCS)2]n(1), where 3-bpd is 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene, has been explored for selective visual detection and effective removal of Hg2+in aqueous medium. [Ni(3-bpd)2(NCS)2]nhas been synthesized under ambient conditions and characterized by elemental analysis, FT-IR spectroscopy, UV-vis spectroscopy, FE-SEM and EDX, XPS and X-ray single crystal diffraction analysis. 1 shows two thiocyanato moieties bound to the hexacoordinated metal center with N atoms whereas the sulfur end remains uncoordinated. The strategy for binding and removal of Hg2+is very simple. Hg2+is known for its affinity for strong bond formation with the soft center, S. The sulfur atoms form bonds with this heavy metal ion. The color of 1 changes from green to grey as Hg atoms form coordinate bonds with S atoms of the SCN-group. It has been found that Hg is present in grey materials in a 2 : 1 ratio (Hg/Ni). 1 is selective for Hg as other metals/metalloids, including heavy metal ions, present in water are unable to change the color of 1 as they do not form any bond with it. Binding of Hg with the S end of the thiocyanato moiety has been confirmed by a number of techniques, e.g. IR and UV-vis spectra, FESEM, EDX, and XPS. Simple filtration is done to separate grey materials for the removal of Hg2+ion from the water medium. A theoretical calculation has been performed to rationalize the fact.
authors.affiliation: Department of Chemistry, Jadavpur University, Jadavpur, Kolkata-700 032, India. proy@chemistry.jdvu.ac.in.
authors.forename: Shibashis
authors.initials: S
authors.lastname: Halder
authors.affiliation: Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India.
authors.forename: John
authors.initials: J
authors.lastname: Mondal
authors.affiliation: Departament de Química, Universitat de les Illes Balears, Crta. De Valldemossa km 7.5, 07122 Palma de Mallorca, Baleares, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Ortega-Castro
authors.affiliation: Departament de Química, Universitat de les Illes Balears, Crta. De Valldemossa km 7.5, 07122 Palma de Mallorca, Baleares, Spain.
authors.forename: Antonio
authors.identifier: http://orcid.org/0000-0001-7840-2139
authors.initials: A
authors.lastname: Frontera
authors.affiliation: Department of Chemistry, Jadavpur University, Jadavpur, Kolkata-700 032, India. proy@chemistry.jdvu.ac.in.
authors.forename: Partha
authors.identifier: http://orcid.org/0000-0001-5387-5626
authors.initials: P
authors.lastname: Roy