Sonya K. Adas

Solvatochromic, thermochromic and pH-sensory DCDHF-hydrazone molecular switch: response to alkaline analytes

Multi-stimuli responsive DCDHF-hydrazone molecular switch containing a hydrazone recognition moiety is developed for the naked-eye detection of alkaline analytes in both vapour and aqueous media. Mechanisms accounting for the thermochromism, pH-sensitivity and solvatochromism are proposed. DCDHF-hydrazone chromophores of different substituents introduced nanostructures with different morphologies via a re-precipitation technique. The films formulated from these nanostructures function as solid-state vapochromic sensors for probing alkaline vapours such as amines and ammonia. The sensing performance is reversible and has differential sensitivity towards a variety of amines at comparable concentrations. The structure of the hydrazone molecular switch was established spectroscopically and by single crystal X-ray crystallography.

Synthesis and Structural Characterization of a Series of Group 11 2,2-Dialkyl-1,3-dicyclohexylguanidinate Complexes

The addition of either lithium dimethylamide or lithium diethylamide to a tetrahydrofuran (THF) solution of 1,3-dicyclohexylcarbodiimide yielded THF adducts of lithium 2,2-dimethyl-1,3-dicyclohexylguandidinate (1) and lithium 2,2-diethyl-1,3-dicyclohexylguandidinate (2), respectively. One equivalent of either 1 or 2 was subsequently reacted with one equivalent of Group 11 halide (CuCl, AgBr, and AuCl) to generate oligonuclear complexes with the general formula {M[CyNC(NR2)NCy]}n where M, R, and n are respectively Cu, CH3, 2 (3); Cu, CH2CH3, 2 (4); Ag, CH3, 3 (5); Ag, CH2CH3, 3 (6); Au, CH3, 2 (7); and Au, CH2CH3, 2 (8). Compounds 1–8 were characterized by single-crystal X-ray diffraction. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, Fourier transform infrared spectroscopy, and 1H, 13C, and 7Li NMR studies. The unique structural aspects of this family of Group 11 complexes are highlighted.

Stability and ring-shift tautomerization of cyclic anhydrides of benzenehexasulfonic acid.

Upon heating in a dry atmosphere, benzenehexasulfonic acid forms three cyclic anhydrides. Mono- and dianhydride do not hydrolyze readily due their flatter structures compared to the hydrolysis products. The trianhydride appears more to be reactive toward hydrolysis. In solutions, the mono- and dianhydride undergo ring-shift tautomerization, which is in the latter case shifted toward the para isomer.

Frontispiece: Synthesis and HNO Donating Properties of the Piloty's Acid Analogue Trifluoromethanesulphonylhydroxamic Acid: Evidence for Quantitative Release of HNO at Neutral pH Conditions

Trifluoromethanesulphonylhydroxamic acid, CF3 SO2 NHOH, is shown to release HNO under physiological pH conditions. A two-step synthesis is presented with the first complete characterization of CF3 SO2 NHOH. This molecule rapidly decomposes in neutral aqueous solution to cleanly release HNO and CF3 SO2- , which was demonstrated using the HNO traps TXPTS and HOCbl, and by 19 F NMR spectroscopy.