Thermal behavior of some new triazole derivative complexes

A series of new complexes with mixed ligands of the type [ML(C₃H₃O₂)₂]·nH₂O (((1) M=Mn, n=1; (2) M=Co(II), n=2; (3) M=Ni(II), n=4; (4) M=Cu(II), n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C₃H₃O₂)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper.     

Coordination polymers and a dinuclear complex constructed from zinc(II) ions and fluorescein: iodine adsorption and optical properties

Abstract

1-D coordination polymers, ¹_∞[Zn(fl)₂]·2EtOH and ¹_∞[Zn(fl)₂]·2MeOH, and a dinuclear complex, [{Zn(fl)₂}₂(dienpip)]·4H₂O·4EtOH (dienpip?= N,N′-bis(2-aminoethyl)piperazine), were obtained using Zn(II) ions and fluorescein anions (fl). Thermal analysis shows stability of the polymers after solvent removal up to more than 400?°C. Crystallization solvent molecules were removed under reduced pressure with the preservation of the polymeric structure, ¹_∞[Zn(fl)₂]. Desolvated crystals were exposed to I₂ vapors and the crystal structure determination by X-ray diffraction confirmed the presence of I₂ molecules in the channels generated in crystals by the metal-organic framework. The iodine content, evaluated by X-ray diffraction, corresponds to the overall formula ¹_∞[Zn(fl)₂]·0.3I₂. The optical properties of the coordination polymers and the dinuclear complex have been investigated.     

Electrochemical Behaviour and Rapid Determination of L‐Dopa at Electrochemically Pretreated Screen Printed Carbon Electrode

A simple and rapid voltammetric method based on a disposable electrochemically pretreated screen‐printed carbon electrode is proposed for the determination of L ‐dopa. Under optimum differential pulse voltammetry conditions a limit of detection of 3.6×10^?7 M for L ‐dopa was obtained. The method was successfully applied to the determination of L ‐dopa in a commercial pharmaceutical formulation.     

Optimization of Biocompatibility for a Hydrophilic Biological Molecule Encapsulation System

Despite considerable advances in recent years, challenges in delivery and storage of biological drugs persist and may delay or prohibit their clinical application. Though nanoparticle-based approaches for small molecule drug encapsulation are mature, encapsulation of proteins remains problematic due to destabilization of the protein. Reverse micelles composed of decylmonoacyl glycerol (10MAG) and lauryldimethylamino-N-oxide (LDAO) in low-viscosity alkanes have been shown to preserve the structure and stability of a wide range of biological macromolecules. Here, we present a first step on developing this system as a future platform for storage and delivery of biological drugs by replacing the non-biocompatible alkane solvent with solvents currently used in small molecule delivery systems. Using a novel screening approach, we performed a comprehensive evaluation of the 10MAG/LDAO system using two preparation methods across seven biocompatible solvents with analysis of toxicity and encapsulation efficiency for each solvent. By using an inexpensive hydrophilic small molecule to test a wide range of conditions, we identify optimal solvent properties for further development. We validate the predictions from this screen with preliminary protein encapsulation tests. The insight provided lays the foundation for further development of this system toward long-term room-temperature storage of biologics or toward water-in-oil-in-water biologic delivery systems.     

Investigations providing a plausible mechanism in the hexamethyldisilazane-catalyzed trimerization of alkyl isocyanates

Using HMDS as catalyst for the trimerization of isocyanates presents many advantages as the expected isocyanurate is not contaminated by the catalyst or other side-products resulting from its degradation. In addition, HMDS presents a low toxicity, and is compatible with industrial applications. This article describes the hexamethyldisilazane (HMDS)-catalyzed trimerization of octylisocyanate. Experimental investigations and mechanistic considerations indicate that the true catalyst of the trimerization is trimethylsilyloctylamine, which results from the preliminary condensation of HMDS with octylisocyanate.     

A Polynomial Time Approximation Scheme for the Grade of Service Steiner Minimum Tree Problem

In this paper, we present the design of a Polynomial Time Approximation Scheme (PTAS) for the Grade of Service Steiner Minimum Tree (GOSST) problem, which is known to be NP-Complete. Previous research has focused on geometric analyses and different approximation algorithms have been designed. We propose a PTAS that provides a polynomial time, near-optimal solution with performance ratio 1+. The GOSST problem has some important applications. In network design, a fundamental issue for the physical construction of a network structure is the interconnection of many communication sites with the best choice of the connecting lines and the best allocation of the transmission capacities over these lines. Good solutions should provide paths with enough communication capacities between any two sites, with the least network construction costs. Also, the GOSST problem has applications in transportation, for road constructions and some potential uses in CAD in terms of interconnecting the elements on a plane to provide enough flux between any two elements.     

Block copolymer containing poly(3‐hexylthiophene) and poly(4‐vinylpyridine): Synthesis and its interaction with CdSe quantum dots for hybrid organic applications

Poly(3‐hexylthiophene)‐b‐poly(4‐vinylpyridine) diblock copolymer was synthesized by RAFT polymerization of 4‐vinyl pyridine using a trithiocarbonate‐terminated poly(3‐hexylthiophene) macro‐RAFT agent. The optoelectronic properties and the morphology of the block copolymer blends with CdSe quantum dots were investigated. UV‐vis and fluorescence experiments were performed to prove the charge transfer between CdSe and poly(3‐hexylthiophene)‐b‐poly(4‐vinylpyridine) diblock copolymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Enhancement of OFET performance of semiconducting polymers containing benzodithiophene upon surface treatment with organic silanes

Poly{4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]dithiophene} ( P1 ) homopolymer and poly{4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]dithiophene ‐alt‐thiophene} ( P2 ) alternating copolymer have been synthesized by Stille coupling polymerization. The field‐effect mobilities of both polymers were measured on both untreated and silane‐treated OFET devices. Various silanes were selected to allow an incremental increase in the hydrophobicity of the silicon dioxide dielectric. A direct correlation was observed between the hydrophobicity of the silicon dioxide dielectric surface and the enhancement of the field‐effect mobilities. The highest mobilities for both polymers were measured on the OFET devices treated with heptadecafluoro‐1,1,2,2‐tetrahydro‐decyl‐1‐trimethoxysilane (FS) which generated the most hydrophobic surface. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011