Thermal Decomposition Processes Of Complexes Research Articles

Effect of pH on the structure and properties of pesticide intercalated into montmorillonite modified by zwitterionic surfactant

DCB (OA, DSB, SB)-MMT complexes were prepared by incorporating zwitterionic surfactants dodecyl dimethyl carboxylbetaine (DCB), N,N-dimethyldodecylamine N-oxide (OA), dodecyl dimethyl sulfobetaine (DSB) and 3-sulphonyl hexadecyldimethylamine (SB) into montmorillonite (MMT). The complexes were characterized by XRD, FT-IR, TGA/DTA and SEM, TEM. Results indicated that the interlayer distances of OA (DSB)-MMT depended on surfactant content and pH value, while those of DCB (SB)-MMT were only related to the surfactant content. The different thermal decomposition processes of complexes were closely related with pH values. Then the pesticide (lambda-cyhalothrin (LCT) or beta-cypermethrin (BCT)) - DCB(SB) micelles were incorporated into the galleries of LCT/DCB-MMT and BCT/SB-MMT hybrids. The basal spaces of LCT/DCB-MMT and BCT/SB-MMT were 4.03 and 4.64 nm, which were larger than those of DCB-MMT and SB-MMT, respectively. The pesticide intercalation was further confirmed by FTIR and TGA/DTA. Furthermore, the release behaviors of BCT (LCT) from the hybrids were compared and analyzed. The pesticide hybrids have the slow release property due to the strong interaction between DCB(SB) and MMT. The pseudo second-order and parabolic diffusion models can be well used to fit the release data. The present study is conducive to the application of MMT as good carriers of pesticide delivery system.

Studies on preparation, crystal structure, thermal properties and fluorescence properties of rare earth complexes composed of 2-chloro-4-fluorobenzoic acid and 2,2':6′,2″-terpyridine

Four new 2D complexes namely [Ln(2-Cl-4-FBA)3(terpy)H2O] (Ln=Er(1),Ho(2)); [Eu(2-Cl-4-FBA)3(terpy)H2O]·1.5H2O(3); [Tb(2-Cl-4-FBA)3(terpy)H2O]·2H2O (4); (2-Cl-4-FBA=2-chloro-4-fluorobenzoate,terpy=2,2':6′,2 ″-terpyridine) were synthesized at normal temperature. The structures of complexes were determined by single-crystal X-ray diffraction. The results show that the two complexes 1-2 are isomorphous and complexes 3-4 are isostructural. Four complexes are both assembled into the 1D and 2D supramolecular structures through the C-H⋯Cl hydrogen bond interactions. The thermal decomposition mechanism of complexes 1-4 was investigated by the technology TG/DSC-FTIR. FTIR spectra were obtained by analyzing the evolved gases in the thermal decomposition process of complexes 1-4. In addition, the differential scanning calorimetry was used to measure the average molar melting values of the complexes 1-2 in the temperature range of 259.15-343.15K by a specific heat comparison method, and the thermodynamic function values were obtained by calculation. The fluorescence tests of complexes 3 and 4 show that both of them have certain luminescent properties.

Biological evaluation, molecular docking, DNA interaction and thermal studies of new bioactive metal complexes of 2‐hydroxybenzaldehyde and fluorobenzamine Schiff base ligand

Schiff base ligand named 2‐((E)‐(2‐fluorophenylimino)methyl)phenol (HL) was prepared by the condensation of 2‐hydroxybenzaldehyde and 2‐fluorobenzamine in 1:1 molar ratio. The coordination behaviour of a series of transition metal ions with the synthesized HL ligand, [Cr(HL)2] (1), [Fe(HL)2] (2), [Co(HL)2] (3) and [Cu(HL)2] (4) is reported. The structure and bonding of the metal complexes have been deduced by analytical and spectral studies. Based on the above studies, the metal centres were found to be octahedral for all the complexes. The activation thermodynamic properties were calculated using the Coats–Redfern method. Thermal decomposition processes of complexes 1, 2, 3 and 4 are non‐spontaneous; that is, the complexes are thermally stable. The positive value of Gibbs free energy of decomposition (ΔG*) for all the complexes is non‐spontaneous processes. DNA binding properties of these metal complexes, investigated using UV–visible absorption, fluorescence and viscosity measurement studies, imply that the complexes bind to DNA by intercalation. The intrinsic binding constant Kb from the electronic absorption studies are 3.12 × 104 M−1, 1.86 × 104 M−1, 3.96 × 104 M−1 and 5.89 × 104 M−1, and the Stern–Volmer quenching constant Ksv values from fluorescence studies are 2.29 × 104 M−1, 1.92 × 104 M−1, 5.62 × 104 M−1 and 8.91 × 104 M−1, for the complexes 1, 2, 3 and 4, respectively. DNA photo cleavage activities of these complexes were studied with supercoiled pUC19 DNA, in the presence of H2O2. GOLD 3.1 program was used to evaluate binding affinities of complexes with human DNA topoisomerase I protein. in vitro cytotoxic and antimicrobial studies revealed higher activity of metal complexes, compared with the ligand.

Copper-metformin ternary complexes: Thermal, photochemosensitivity and molecular docking studies

The copper(II) complexes [Cu(Cl)2(met)(o-phen)] (1), [Cu(Cl)2(met)(en)] (2) and [Cu(Cl)2(met)(opda)] (3) (met = metformin, o-phen = ortho-phenanthroline, en = ethylenediamine, opda = ortho-phenylenediamine) were synthesized and characterized by LC-MS, elemental analysis, molar conductance, thermal analysis, infrared spectra, magnetic moment, electronic spectra and XRD studies. The metal center was found in an octahedral geometry. The activation thermodynamic properties were calculated using Coats-Redfern method. Thermal decomposition processes of complexes 1, 2, 3 are non-spontaneous, i.e., the complexes are thermally stable. The positive value of Gibbs free energy of decomposition (ΔG⁎) for the Cu(II) complexes is non-spontaneous processes. UV–Visible absorption, fluorescence, and viscosity measurements have been conducted to assess the interaction of the complexes with CT DNA. The complexes showed absorption hyperchromism in its UV–Vis spectrum with DNA. The binding constants Kb from UV–Vis absorption studies were 4.6 × 105, 1.48 × 105, 2.09 × 105 M−1 for 1, 2, 3 respectively and Stern–Volmer quenching constants (Ksq) from fluorescence studies were 0.636, 0.293, 0.487 for 1, 2, 3 respectively. Finally, viscosity measurements revealed that the binding of the complexes with CT-DNA could be surface binding, mainly due to groove binding. The activity of complexes towards DNA cleavage decreases in the order of 1 > 3 > 2. The complexes were docked in to B-DNA sequence, 5′(D*AP*CP*CP*GP*AP*CP*GP*TP*CP*GP*GP*T)-3′ retrieved from protein data bank (PDB ID: 423D), using Discovery Studio 2.1 software.

A Series of Transition-metal Coordination Complexes Assembled from 3-Nitrophthalic Acid and Thiabendazole: Synthesis, Structure and Properties

In order to explore new coordination frameworks with novel designed 3-nitrophthalic acid and the same N-donor ancillary ligand, a series of novel coordination complexes, namely, (1), (2), (3), (4) (3- = 3-nitrophthalic acid), have been hydrothermally synthesized through the reaction of 3-nitrophthalic acid with divalent transition-metal salts in the presence of N-donor ancillary coligand (TBZ = thiabendazole). As a result of various coordination modes of the versatile 3- and the coligand TBZ, these complexes exhibit structural diversity. X-ray structure analysis reveals that 1 and 2 are 0D molecular rings, while 3 and 4 are one-dimensional (1D) infinite chain polymers. And the weak O-HO hydrogen bonds and C-HO nonclassical hydrogen bonds as well as stacking also play important roles in affecting the final structure where complexes 1, 3 and 4 have 3D supramolecular architectures, while complex 2 has a 2D supramolecular network. Also, IR spectra, fluorescence properties and thermal decomposition process of complexes 1-4 were investigated.

Synthesis, structures, characterization and antimicrobial activity of two novel coordination complexes derived from 2-naphthoxyacetic acid

Two novel coordination complexes, namely, [Cd(2-NOA)2(TBZ)2] (1) and [Mn(2-NOA)2(H2O)2]n (2) (2-NOAH = 2-naphthoxyacetic acid), have been hydrothermally synthesized through the reaction of 2-naphthoxyacetic acid with or without N-donor ancillary coligand (thiabendazole, TBZ) in the presence of divalent transition-metal salts. Complex 1 is a zero-dimensional (0D) molecule, and the self-complementary C–H···O hydrogen bonds extend these molecules into a 2D supramolecular framework. In polymer 2, 2-NOA− acts as a bridging ligand to bind Mn(II) ions to form a 2D supermolecular assembly. Also, IR spectra, powder X-ray diffraction, fluorescence properties and thermal decomposition process of complexes were investigated. The effect of the TBZ base ligand and the complex 1 on the antimicrobial activity against Candida albicans was studied.

Crystal Structures and Electrochemical Property of Two Novel Complexes [Cu(o‐phth)(H2O)]n and [Co(3‐nitro‐phth)(4,4′‐bipy)2(H2O)3

A copper(II) complex with o‐phthalate acid [Cu(o‐phth)(H2O)]n (1) and a cobalt(II) complex with 3‐nitro‐phthalic acid and 4,4′‐bipyridine [Co(3‐nitro‐phth) (4,4′‐bipy)2(H2O)3]n (2) have been synthesized. These two novel complexes were characterized by IR, X‐ray crystallography diffraction. Complex 1 belongs to monoclinic crystal with C2 (1)/c space group, the complex 2 triclinic crystal with P‐1. Also, electrochemical properties of these complexes and thermal decomposition process of complex 1 were investigated.

Synthesis, Characterization and Thermal Decomposition of p-iodo-phenylalanine Complexes of Cobalt or Nickel

New complexes of the non-natural amino acid (p-iodo-phenylalanine) with divalent cobalt and nickel ions have been synthesized. The composition of the complexes is [M(IC6H4CH2CHNH2COO)2]×2.5H2O (M=Co, Ni) and the crystal structure belongs to orthorhombic system. Infrared spectra indicate the nature of bonding in the complex. The first stage in the thermal decomposition process of the complex shows the presence of crystal water. The thermal decomposition process of cobalt complex differs from that of nickel. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reactions. Thermal analysis indicates that the iodine atom of the ligand may coordinate to the metal ion in the lattice.

Thermal decomposition process of some rare-earth-nitrilotriacetic acid-serine mixed complexes

Thermal decomposition processes of the mixed complexes of nitrilotriacetates of Pr, Sm, Tb, Ho and Tm with 2-amino-3-hydroxypropionic acid have been investigated. The results indicate that serine may coordinate to the rare earth ion via its hydroxyl group, not by means of its carboxyl group. From the thermogravimetric and the derivative thermogravimetric curves it can be deduced that there may be six or seven steps in the thermal decomposition process of these mixed complexes, and that not all thermal decomposition processes in these mixed complexes are the same. Some possible thermal decomposition reactions have been proposed, and the differences between the thermal decomposition processes of these complexes are also discussed.