Jae Sang Kim

Structural Selectivity of Calix(m)pyrroles(n)furans (m + n = 4) as Ionophores in Ag(I) Ion-Selective Electrodes

A series of octamethylcalix[m]pyrroles[n]furans (m + n = 4), such astrans-octamethylcalix[2]pyrroles[2]furans L1),cis-octamethylcalix[2]pyrroles[2]furans (L2) and octamethylcalix[1]pyrrole[3]furans (L3) have been studied as sensors in liquid membrane ion-selective electrodes for Ag(I) ion. The electrode based on L1, trans-N2O2 porphyrinogen, gave the best results with a wide working concentration range of 1.0 × 10-1 - 1.0 × 105.6 M and a Nernstian slope of 57.0 mV/decade. This electrode exhibited a fast response time of 30 s and high selectivity over a number of mono-, di- and tri-valent cations, with only Tl(I) and Hg(II) ion interferences. The effect of anion excluders on the performance of the membrane electrodes has been also studied. The electrode based on L1 showed no significant potential changes in the range 2.5 < pH < 7.5. The crystalstructure of L3, NO3 porphyrinogen, was determined by single crystal X-ray analysis. The crystallographic analysis of L3 reveals that its structure is a saddle-shaped 1,3-alternate conformation with enough space to accommodate Ag(I) in the three dimensional cavity.

Double-armed crown ethers: Synergic π-coordination effect on potentiometric sensing for Ag(I)

Three diaza-18-crown-6 derivatives having methyl (L1), methoxy (L2) and phenyl (L3) end-groups in para-substituted phenolic side-arms have been investigated as potentiometric sensing materials for silver(I)-selective poly(vinyl chloride) membrane electrodes. The aim of the present work is to establish whether a combination of macrocyclic coordination to Ag+ ion and Ag-pi interaction might produce synergic effect in Ag+ ion sensing. The electrode based on the aromatic end-groups, L3 was found to give remarkably better electrochemical performance than their aliphatic counterparts (L1 and L2). The sensing ability for Ag+ ion with the proposed electrode was enhanced noticeably due to the pi-coordination of Ag+ ion, which was elucidated by NMR. The present findings may serve as an alternative approach for designing advanced sensing materials.

Flutolanil [N-(3-isopropoxyphen-yl)-2-(trifluoro-meth-yl)benzamide].

The title compound, C17H16F3NO2, crystallizes with two independent molecules in the asymmetric unit. The dihedral angles between the isopropoxyphenyl and trifluoromethylphenyl rings are 85.78 (5) and 63.15 (6)° in the two molecules. In the crystal structure, intermolecular N—H⋯O and C—H⋯π interactions are observed.

(1H-Pyrrol-2-ylmethylidene)(3-{[(1H-pyrrol-2-ylmethylidene)amino]methyl}benzyl)amine

In the title compound, C18H18N4, the dihedral angles between the pyrrole rings and the phenyl ring are 85.07 (8)° and 77.13 (9)°. Intermolecular N—H⋯N hydrogen bonds contribute to the stabilization of the crystal packing.

2,9,18-Trioxo-3,5,8,19-tetra­aza-[55,13][11]­metaphane monohydrate

In the title compound, C18H26N4O4, the bridgehead N atom is located toward the inside of the cage and the displacement from the aromatic ring is 4.2110 (13) A. The three C atoms adjacent to the bridgehead N atom are disordered with roughly equal occupancy between two sets of positions.