Triazole Complex Research Articles

Triazolic compounds as corrosion inhibitors for copper in hydrochloric acid

PurposeTo correlate the inhibitory effect of triazole compounds on the corrosion of copper in HCl at various temperatures by semi‐empirical molecular orbital theory.Design/methodology/approachTwo triazoles were selected as the best inhibitors among the triazole compounds tested. Gravimetric and electrochemical measurements were conducted.FindingsCorrelation between inhibition efficiency and calculation of molecular orbital of triazole compounds was obtained. Cu(I)‐triazole complex formation was confirmed by UV spectroscopy.Research limitations/implicationsThe calculation of energetic levels of molecular orbital may be a tool to explain the classification of inhibitor efficiency.Practical implicationsThe theoretical calculation is a complementary mean to selecting an efficient inhibitor among a given series. Good agreement between the experimental methods explored and theoretical calculations was observed.Originality/valueThe originality of this work was the finding of the correlation between energetic levels of orbital molecular and inhibitor efficiency of triazole compounds. The confirmation of the formation of Cu(I)‐triazole by UV‐visible spectroscopy was also new.

Syntheses, Structures, and Magnetic Properties of Unusual Nonlinear Polynuclear Copper(II) Complexes Containing Derivatives of 1,2,4-Triazole and Pivalate Ligands

Novel polynuclear Cu(II) complexes containing derivatives of 1,2,4-trizaole and pivalate ligands, [Cu(3)(mu(3)-OH)(mu-adetrz)(2)(piv)(5)(H(2)O)].6.5H(2)O (1) (adetrz = 4-amino-3,5-diethyl-1,2,4-triazole, piv = pivalate), [Cu(4)(mu(3)-OH)(2)(mu-atrz)(2)(mu-piv)(4)(piv)(2)].2MeOH.H(2)O (2) (atrz = 4-amino-1,2,4-triazole), [Cu(4)(mu(3)-OH)(2)(mu-tbtrz)(2)(mu-piv)(2)(piv)(4)].4H(2)O (3) (tbtrz = 4-tert-butyl-1,2,4-trizaole), and [Cu(4)(mu(3)-O)(2)(mu-admtrz)(4)(admtrz)(2)(mu-piv)(2)(piv)(2)].2[Cu(2)(mu-H(2)O)(mu-admtrz)(piv)(4)].13H(2)O [4 = 4a.2(4b).13H(2)O; admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole], have been prepared and structurally characterized. 1 is an asymmetrical triangular complex containing a [Cu(3)(mu(3)-OH)] core with two Cu---Cu edges spanned by bridging adetrz ligands. 2, 3, and 4a are novel tetranuclear compounds containing a [Cu(4)(mu(3)-O)(2)] or [Cu(4)(mu(3)-OH)(2)] core with Cu---Cu edges spanned by bridging 1,2,4-triazole or pivalate ligands. 4b is a dinuclear compound with one admtrz and one water bridge, and it is the first dinuclear Cu(II) triazole complex with one bridging water molecule. 1 is one of few reported triangular Cu(II) complexes with derivatives of 1,2,4-triazole, while 2, 3, and 4a are the first group of the nonlinear tetranuclear Cu(II) compounds with derivatives of 1,2,4-triazole. Variable-temperature magnetic susceptibility studies on the powder samples of 1-3 reveal the overall antiferromagnetic coupling between Cu(II) ions with J values of -55.6 to -12.8 cm(-1) (1), -216.4 to 0 cm(-1) (2), and -259.8 to 4.8 cm(-1) (3).

新しい自己組織化材料：一次元金属錯体を主鎖とするナノワイヤーの開発

The ability to manipulate nano to microscopic superstructures based on molecular self-assembly holds a key to develop future nanomaterials. In this review, the design and synthesis of self-assembling inorganic nanowires are introduced. First, lipophilic nanowires consisting of cationic, one-dimensional mixed valence PtII/PtIV complex and anionic lipids are developed. They display thermal dissociation and re-assembling characteristics and provide the first example of self-assembling conjugated nanowires. It also enables bottom-up manipulation of stereo-nanoarchitectures on solid surfaces. Second, heat-set gel-like networks are self-assembled from lipophilic Co (II) triazole complex in chloroform. It affords blue gel at room temperature, whose color is characteristic of the tetrahedral (Td) coordination structure. Upon cooling, the gel is dissolved into pale pink solution (Oh complex) and this change was thermally reversible. The reversible, heat-set gelation of organic liquids has been unprecedented. These new approaches and findings provide new dimensions in the fields of nano- and materials chemistry.

Switching of spin states triggered by a phase transition: spin-crossover properties of self-assembled iron(II) complexes with alkyl-tethered triazole ligands.

Iron(II) complexes of triazole derivatives having two C12 and C16 long alkyl chains, (C12trz)FeII and (C16trz)FeII, serve as novel spin-crossover materials, which display a spin-state transition in response to a phase transition. In contrast, a triazole complex with two C8 alkyl chains ((C8trz)FeII) exhibits only a poor response. EXAFS and XRD analyses of (C16trz)FeII indicate an interdigitating self-assembled structure of polynuclear iron(II) species. According to DSC, VT-IR, and VT-XRD profiles, the spin-state transition is triggered by melting of the interdigitating alkyl chains, which is likely responsible for the "lock-and-release" feature of the spin state. By virtue of the thermoreversibility of the phase transition, the spin crossover could be repeated without deterioration.

Synthesis and antimicrobial activity of Ni(II), Co(II), Zn(II) and Cd(II) complexes of 4-substituted-3-mercapto-5-phenyl-4H-1,2,4-triazoles

Ni(II), Co(II), Zn(II) and Cd(II) complexes of 3-mercapto-4-phenyl(cyclohexyl)-4H-1,2,4-triazoles were prepared and characterized by elemental analyses and standard spectroscopic techniques. In vitro antimicrobial activity of the complexes was determined against a variety of bacterial (Gram-positive and Gram-negative) and fungal species. While the Ni, Co and Zn complexes exhibited little or no activity against the organisms studied in this work, complexes of both the 4-phenyl 13 and 4-cyclohexyl 12 substituted triazoles were highly active as antifungal agents. Both 12 and 13, while significantly superior to the prototypical antifungal nystatin in inhibiting the growth of Candida albicans and Candida pseudotropicalis, showed equal effectiveness against Saccharomyces cerevisiae. The antibacterial activity of the Cd complexes was better than that observed for any of the other metal complexes, but generally not comparable to that of the reference antibiotic, streptomycin with the exception of the 4-cyclohexyl triazole complex 12, which was equivalent to streptomycin against Staphylococcus aureus and Escherichia coli.

The inhibition of zinc corrosion by bisaminotriazole and other triazole derivatives

The inhibition of zinc corrosion by various triazole derivatives was investigated with respect to dependence on pH, potential E, inhibitor concentration c Inh, zinc ion concentration c Zn 2+ , and exposure time t. Current potential curves and measurements of weight loss show that 3-amino-5-heptyl-1,2,4-triazole (AHT) is an excellent inhibitor of zinc corrosion in acid and weak alkaline solutions, while bisaminotriazole (BAT4) gives the best inhibition efficiency expecially at pH 9 and low inhibitor concentrations. Capacity potential curves and XPS-measurements show the formation of protective triazole layers with a maximum thickness of about 3 nm. The chemical analysis of insoluble zinc triazole complexes precipitated in solution yields a stoichiometric ratio of Zn 2+ and the triazole ring of 1 : 2. The presence of zinc triazole complex on the zinc surface is shown by XPS spectroscopy. The solubility, adsorbability and hydrophobicity of the triazole molecules and the stability of the zinc-triazole complexes are found to be the most important factors influencing the inhibition efficiency of the triazole derivatives under varying conditions.

Reaction of dicarbonyl ( pentahapto-cyclopentadienyl)(olefin)iron cations with sodium azide

Reaction of the ( h 5-C 5H 5)Fe(CO) 2(C 2H 4) cation with sodium azide yields the azido complex ( h 5-C 5H 5)Fe(CO) 2N 3 by ligand displacement, rather than the isocyanate complex ( h 5-C 5H 5)Fe(CO)(C 2H 4(NCO) as had previously been reported. The azido complex may also be obtained from other ( h 5-C 5H 5)Fe(CO) 2(olefin) cations or in low yield from ( h 5-C 5H 5)Fe(CO) 2Cl. The azido complex is converted to the isocyanate complex ( h 5-C 5H 5)Fe(CO) 2(NCO) in low yield by photolysis, and to a triazole complex on treatment with dimethyl acetylenedicarboxylate.