title: A Highly Selective Chemosensor for Cyanide Derived from a Formyl-Functionalized Phosphorescent Iridium(III) Complex.
abstract: A new phosphorescent iridium(III) complex, bis[2',6'-difluorophenyl-4-formylpyridinato-N,C4']iridium(III) (picolinate) (IrC), was synthesized, fully characterized by various spectroscopic techniques, and utilized for the detection of CN(-) on the basis of the widely known hypothesis of the formation of cyanohydrins. The solid-state structure of the developed IrC was authenticated by single-crystal X-ray diffraction. Notably, the iridium(III) complex exhibits intense red phosphorescence in the solid state at 298 K (ΦPL = 0.16) and faint emission in acetonitrile solution (ΦPL = 0.02). The cyanide anion binding properties with IrC in pure and aqueous acetonitrile solutions were systematically investigated using two different channels: i.e., by means of UV-vis absorption and photoluminescence. The addition of 2.0 equiv of cyanide to a solution of the iridium(III) complex in acetonitrile (c = 20 μM) visibly changes the color from orange to yellow. On the other hand, the PL intensity of IrC at 480 nm was dramatically enhanced ∼5.36 × 10(2)-fold within 100 s along with a strong signature of a blue shift of the emission by ∼155 nm with a detection limit of 2.16 × 10(-8) M. The cyanohydrin formation mechanism is further supported by results of a (1)H NMR titration of IrC with CN(-). As an integral part of this work, phosphorescent test strips have been constructed by impregnating Whatman filter paper with IrC for the trace detection of CN(-) in the contact mode, exhibiting a detection limit at the nanogram level (∼265 ng/mL). Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed to understand the electronic structure and the corresponding transitions involved in the designed phosphorescent iridium(III) complex probe and its cyanide adduct.
authors.affiliation: Materials Science and Technology Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST) , Thiruvananthapuram 695 019, India.|Academy of Scientific and Innovative Research (AcSIR) , New Delhi 110025, India.
authors.forename: K S
authors.initials: KS
authors.lastname: Bejoymohandas
authors.affiliation: Materials Science and Technology Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST) , Thiruvananthapuram 695 019, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Materials Science and Technology Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST) , Thiruvananthapuram 695 019, India.
authors.forename: S
authors.initials: S
authors.lastname: Sreenadh
authors.affiliation: Chemical Laboratory, CSIR-Central Leather Research Institute , Chennai 600 020, India.
authors.forename: E
authors.initials: E
authors.lastname: Varathan
authors.affiliation: Materials Science and Technology Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST) , Thiruvananthapuram 695 019, India.
authors.forename: S
authors.initials: S
authors.lastname: Varughese
authors.affiliation: Chemical Laboratory, CSIR-Central Leather Research Institute , Chennai 600 020, India.
authors.forename: V
authors.initials: V
authors.lastname: Subramanian
authors.affiliation: Materials Science and Technology Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST) , Thiruvananthapuram 695 019, India.|Academy of Scientific and Innovative Research (AcSIR) , New Delhi 110025, India.
authors.forename: M L P
authors.initials: ML
authors.lastname: Reddy