A PVC-based membrane of 2,2,2-cryptand exhibits a very good response for Zn2+ in a wide concentration range (from 2.06 ppm to 6.54 × 103 ppm) with a slope of 22.0 mV/decade of Zn2+ concentration. The response time of the sensor is <10 s, and the membrane can be used for more than 3 months without any observed divergence in potentials. The proposed sensor exhibits very good selectivity for Zn2+ over other cations and can be used in a wide pH range (2.8−7.0). It has also been possible to use this assembly as an indicator electrode in potentiometric titrations involving zinc ions.

PVC-Based 2,2,2-Cryptand Sensor for Zinc Ions.

Publisher Summary Saturated six-membered heterocyclic rings can be found in natural products, drugs, and polymers. The methodologies for studying the conformers at equilibrium and their rates of interconversion are mainly based on nuclear magnetic resonance (NMR) spectroscopy. This chapter provides the conformational analysis and stereodynamics of saturated heterocyclic six-membered rings. The cyclohexane-like rings are characterized by the presence of various nonplanar conformations: chair, boat, and twist conformations. The conformational equilibria in six methylcyclohexanes are examined in the chapter using the temperature dependence of the 13 C chemical shifts at temperatures above the coalescence point. The conformational enthalpy (∆H°), entropy (∆S°) and free energy (∆G°) of methyl-, ethyl-, and iso-propyl-cyclohexane for monosubstituted and polysubstituted cyclohexanes in solution are examined in the chapter both experimentally and computationally. The stereochemistry, physical and chemical properties, and some transformations of 1,3-oxathianes—especially alkyl substituent effects on the preferred conformers—are also reviewed in the chapter. The synthesis and conformational analysis of the condensed-skeleton saturated heterocycles are also described in the chapter. The preferred conformers of six-membered rings with one exo- or endo-double bond in the solid state are tabulated in the chapter.

Conformational Analysis of Saturated Heterocyclic Six-Membered Rings

Magnesium–tetrazaporphyrin incorporated PVC matrix as a new material for fabrication of Mg2+ selective potentiometric sensor

Trans-1,2-cyclohexanedicarboxylic acid derivatives as ph-trigger for conformationally controlled crowns

A new fluorescent reagent (1) which has two anthracene moieties at both terminals of linear polyether was synthesized, and the complexation behavior of 1 with alkaline earth metal ions was investigated. At the complexation with the metal ions, the fluorescence spectrum of 1 changed from that of monomer to dimer of anthracene. 1 formed both 1 : 1 and 1 : 2 complexes with alkaline earth metal ions, and the complex formation was selective to Ca2+.

Syntheses and Complexing Behavior of New Fluorescent Reagents for Alkaline Earth Metal Ions

Several trans-cyclohexano crown ethers have been synthesized and studied as sensor materials for different metal cations in PVC-matrix membranes of ion-selective electrodes. The potentiometric selectivity of the membranes has been found to correlate with the chemical structure peculiarities of the incorporated compound and can be changed by variation of the substituent attached to the cyclohexane fragment. Some of the compounds show superior selectivity for potassium over many other metal cations.

trans-Cyclohexano crown ethers as ion sensors in cation-selective electrodes

Macrocyclization with Participation of ThiyI Radicals: Construction of 18- and 9-Membered Crown Thioethers

Stereochemical studies of mono- and 2,3-disubstituted 1,4-dithianes and sulfur- and oxygen-containing macrocycles by means of NMR measurements, X-ray crystal structure analysis and molecular mechanics calculations revealed new conformational regularity and peculiarities.

V. V. Samoshin

Papers

trans-Cyclohexano crown ethers as ion sensors in cation-selective electrodes

Macrocyclization with Participation of ThiyI Radicals: Construction of 18- and 9-Membered Crown Thioethers

Conformational Effects in Sulfur-Containing Six-Membered Cycles and Macrocycles

Conformation properties of trans-cyclohexanotrithiacrown-esters

Conformation characteristics of trans-cyclohexanotrithiacrown ethers