Jeong Mi Bae

A single colorimetric sensor for multiple target ions: the simultaneous detection of Fe2+ and Cu2+ in aqueous media

This study demonstrates the design, synthesis and sensing properties of a simple and efficient chemosensor 1 (1 = 2,6-bis((2-(((pyridine-2-yl)methylamino)methyl)phenol)ethylamido)pyridine) to rapidly detect Fe2+ and Cu2+ in aqueous solution (bis-tris buffer/DMF (8/2, v/v)), exploiting UV-vis spectral analysis, naked-eye and paper devices. The sensor 1 showed significant absorption spectra at 455 nm for Fe2+ and 660 nm for Cu2+, which are responsible for color changes due to the metal-to-ligand charge-transfer. The binding modes of 1 with Fe2+ or Cu2+ have been investigated by Job plot and ESI-mass analysis. In addition, the sensor 1 could be recyclable simply through treatment with a proper reagent such as EDTA. Moreover, the sensor has been used in the development of practically viable colorimetric kits.

Catalysis and molecular magnetism of dinuclear iron(III) complexes with N-(2-pyridylmethyl)-iminodiethanol/-ate

The reaction of N-(2-pyridylmethyl)iminodiethanol (H2pmide) and Fe(NO3)3·9H2O in MeOH led to the formation of a dimeric iron(III) complex, [(Hpmide)Fe(NO3)]2(NO3)2·2CH3OH (1). Its anion-exchanged form, [(pmide)Fe(N3)]2 (2), was prepared by the reaction of 1and NaN3 in MeOH, during which the Hpmide ligand of 1 was also deprotonated. These compounds were investigated by single crystal X-ray diffraction and magnetochemistry. In complex 1, one iron(III) ion was bonded with a mono-deprotonated Hpmide ligand and a nitrate ion. The two iron(III) ions within the dinuclear unit were connected by two ethoxy groups with an inversion center. In 2, one iron(III) ion was coordinated with a deprotonated pmide ligand and an azide ion. The Fe(pmide)(N3) unit was related by symmetry through an inversion center. Both 1 and 2 efficiently catalyzed the oxidation of a variety of alcohols under mild conditions. The oxidation mechanism was proposed to involve an Fe(IV)=O intermediate as the major reactive species and an Fe(V)=O intermediate as a minor oxidant. Evidence for this proposal was derived from reactivity and Hammett studies, KIE (kH/kD) values, and the use of MPPH (2-methyl-1-phenylprop-2-yl hydroperoxide) as a mechanistic probe. Both compounds had significant antiferromagnetic interactions between the iron(III) ions via the oxygen atoms. 1 showed a strong antiferromagnetic interaction within the Fe(III) dimer, while 2 had a weak antiferromagnetic coupling within the Fe(III) dimer.

CO2 selective dynamic two-dimensional ZnII coordination polymer

A CO2 selective dynamic two-dimensional (2D) MOF system, [Zn(glu)(μ-bpe)]·2H2O (·2H2O) (glu = glutarate, bpe = 1,2-bis(4-pyridyl)ethylene), is prepared. Based on variable temperature PXRD patterns, I·2H2O exhibits a structural transformation of the framework upon desolvation. Various gas sorption analyses at low temperatures reveal that solvent-free I selectively adsorbs CO2 over N2, H2, and CH4. Stepped CO2 isotherms for solvent-free I with a large hysteresis between adsorption and desorption branches at 196 K indicate that I is a dynamic framework. Moreover, I·2H2O shows efficient heterogeneous catalytic reactivity for transesterification of various esters. The catalyst can be recycled multiple times without losing its original activity.

Synthesis, Characterization, and Efficient Catalytic Activities of a Nickel(II) Porphyrin: Remarkable Solvent and Substrate Effects on Participation of Multiple Active Oxidants

A new nickel(II) porphyrin complex, [NiII (porp)] (1), has been synthesized and characterized by 1 H NMR, 13 C NMR and mass spectrometry analysis. This NiII porphyrin complex 1 quantitatively catalyzed the epoxidation reaction of a wide range of olefins with meta-chloroperoxybenzoic acid (m-CPBA) under mild conditions. Reactivity and Hammett studies, H218 O-exchange experiments, and the use of PPAA (peroxyphenylacetic acid) as a mechanistic probe suggested that participation of multiple active oxidants NiII -OOC(O)R 2, NiIV -Oxo 3, and NiIII -Oxo 4 within olefin epoxidation reactions by the nickel porphyrin complex is markedly affected by solvent polarity, concentration, and type of substrate. In aprotic solvent systems, such as toluene, CH2 Cl2 , and CH3 CN, multiple oxidants, NiII -(O)R 2, NiIV -Oxo 3, and NiIII -Oxo 4, operate simultaneously as the key active intermediates responsible for epoxidation reactions of easy-to-oxidize substrate cyclohexene, whereas NiIV -Oxo 3 and NiIII -Oxo 4 species become the common reactive oxidant for the difficult-to-oxidize substrate 1-octene. In a protic solvent system, a mixture of CH3 CN and H2 O (95:5), the NiII -OOC(O)R 2 undergoes heterolytic or homolytic O-O bond cleavage to afford NiIV -Oxo 3 and NiIII -Oxo 4 species by general acid catalysis prior to direct interaction between 2 and olefin, regardless of the type of substrate. In this case, only NiIV -Oxo 3 and NiIII -Oxo 4 species were the common reactive oxidant responsible for olefin epoxidation reactions.

CCDC 806246: Experimental Crystal Structure Determination

Related Article: Geun Hee Eom, Jin Hoon Kim, Young Dan Jo, Eun Young Kim, Jeong Mi Bae, Cheal Kim, Sung-Jin Kim, Youngmee Kim|2012|Inorg.Chim.Acta|387|106|doi:10.1016/j.ica.2012.01.002

CCDC 806244: Experimental Crystal Structure Determination

Related Article: Geun Hee Eom, Jin Hoon Kim, Young Dan Jo, Eun Young Kim, Jeong Mi Bae, Cheal Kim, Sung-Jin Kim, Youngmee Kim|2012|Inorg.Chim.Acta|387|106|doi:10.1016/j.ica.2012.01.002