Studies on 4‐Thiazolidinones: Scope of the Reactions of 3‐Aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones with Cyanide and Cyanate Ions

Treatment of 3‐aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones 1 with CN^? and NCO^? effected the ring cleavage providing [(cyanocarbonothioyl)amino]benzenes 4 and arylisothiocyanates 5 , respectively. Similar treatment of 5‐(2‐aryl‐2‐oxoethyl) derivatives 2 afforded 2,4‐bis(2‐aryl‐2‐oxoethylidene)cyclobutane‐1,3‐diones 6 along with each of the preceding products. Treatment of the respective (E,Z)‐5‐(2‐aryl‐2‐oxoethylidene) analogues 3b and 3c with CN^? gave 4b and 4c and 2‐(arylcarbonyl)‐2‐methoxy‐4‐oxopentanedinitriles 7b and 7c , in addition to 3,6‐bis[2‐(4‐chlorophenyl)‐1‐methoxy‐2‐oxoethylidene]‐1,4‐dithiane‐2,5‐dione 8c , which has been generated from 3c . Reactions of 3c or 3d with NCO^? provided 5c or 5d , together with 8c or 8d as pure isomers. In the formation of the MeO products 7 and 8 , the solvent (MeOH) has participated. Structures of these products are based on microanalytical and spectroscopic data. Rationalizations for the above transformations are given.     

Transition metal complexes of a hydrazone–oxime ligand containing the isonicotinoyl moiety: Synthesis,characterization and microbicide activities

Complexes of VO²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ru³⁺ and UO₂²⁺ with (3‐(hydroxyimino)butan‐2‐ylidene)isonicotinohydrazide were synthesized and characterized using physical and spectral methods. Analytical data revealed that the complexes formed in 1:1 or 1:2 metal–ligand ratios. Spectral studies showed that the ligand bonded to the metal ion in neutral tridentate, monobasic tridentate or monobasic bidentate fashion through azomethine nitrogen atom, protonated/deprotonated imine oxime group and/or ketonic/enolic carbonyl group. From the electronic spectral data together with magnetic susceptibility values a square planar, tetrahedral or distorted octahedral structure can be proposed for all complexes. Electron spin resonance spectra for Cu²⁺ complexes ( 2 – 4 ) revealed axial symmetry with g_|| > g_⊥ > g_e, indicating distorted octahedral or square planar structures and the unpaired electron exists in a orbital with marked covalent bond feature. The prepared complexes showed good to excellent biological activity, and the most active complexes against Aspergillus niger were 4 and 9 with zone of inhibition of 25 and 23 mm, respectively. Complexes 10 and 11 showed interesting activity against Escherichia coli with zone of inhibition of 44 and 32 mm, respectively.     

Electro‐assisted solid‐phase microextraction based on poly(3,4‐ethylenedioxythiophen) combined with GC for the quantification of tricyclic antidepressants

In this study, a platinum wire coated with poly(3,4‐ethylenedioxythiophen) was used as an electro‐assisted solid‐phase microextraction fiber for the quantification of tricyclic antidepressant drugs in biological samples by coupling to GC employing a flame ionization detector. In this study, an electric field increased the extraction rate and recovery. The fiber used as a solid phase was synthesized by the electropolymerization of 3,4‐ethylenedioxythiophen monomers onto a platinum wire. The ability of this fiber to extract imipramine, desipramine, and clomipramine by using the electro‐assisted solid‐phase microextraction technique was evaluated. The effect of various parameters that influence the extraction efficiency, which include solution temperature, extraction time, stirring rate, ionic strength, time and temperature of desorption, and thickness of the fiber, was optimized. Under optimized conditions, the linear ranges and regression coefficients of calibration curves were in the range of 0.5–250 and 0.990–0.998 ng/mL, respectively. Detection limits were in the range of 0.15–0.45 ng/mL. Finally, this method was applied to the determination of drugs in urine and wastewater samples and recoveries were 4.8–108.9%.     

Spectral and Structural Studies of the Copper(II) Complexes of 3, 4‐Hexanedione Bis(3‐azacyclothiosemicarbazones)

Copper(II) complexes of 3, 4‐hexanedione bis(piperidyl‐ and bis(hexamethyleneiminylthiosemicarbazone), H₂Hxpip and H₂Hxhexim, respectively, have been prepared and studied spectroscopically. The bis(thiosemicarbazones) have been characterized by their melting points, as well as IR, electronic and ¹H NMR spectra. Upon formation of their copper(II) complexes, loss of the hydrazinic hydrogen atoms occurs, and the ligands coordinate as dianionic, tetradentate N₂S₂ ligands. The crystal structures of H₂Hxpip, its 4‐coordinate copper(II) complex, [Cu(Hxpip)], and the related [Cu(Hxhexim)] have been determined by single crystal x‐ray diffraction. The nature of the four‐coordinate copper(II) complexes have also been characterized by ESR, IR, and electronic spectroscopy, as well as magnetic moments and elemental analyses.     

Application of a new fiber coating based on electrochemically reduced graphene oxide for the cold‐fiber headspace solid‐phase microextraction of tricyclic antidepressants

A new fiber based on the electrochemical reduction of graphene oxide was prepared on a copper wire for solid‐phase microextraction (SPME) applications. The prepared fiber was used for the SPME and gas chromatographic analysis of tricyclic antidepressants (TCADs), including amitriptyline, trimipramine, and clomipramine. The feasibility of direct‐immersion and headspace modes of SPME for the determination of TCADs was studied. The effects of four parameters including pH, salt content, extraction temperature with and without cooling the fiber, and extraction time were investigated. The comparison showed that headspace cold fiber SPME results in the best outcome for the extraction of TCADs. Under the optimized conditions of this mode, the calibration curves were linear between 2.0 and 500 ng/mL and the detection limits were between 0.30 and 0.53 ng/mL. The intraday and interday RSDs obtained at 20 ng/mL (n = 5), using a single fiber, were 5.5–9.0 and 7.5–9.8, respectively. The fiber to fiber repeatability (n = 4), expressed as the RSD, was between 12.8 and 13.2% at a 20 ng/mL concentration level. The method was successfully applied to the analysis of TCADs in plasma samples showing recoveries from 73 to 96%.