Metal Complexes of a Novel Terpolymer Ligand: Synthesis, Spectral, Morphology, Thermal Degradation Kinetics and Antimicrobial Screening

2-amino-6-nitro-benzothiazole and thiosemicarbazide with formaldehyde (BTF) terpolymer ligand and its metal complexes have been synthesized. The plausible structure of the synthesized BTF terpolymer ligand was elucidated on the basis of elemental analysis and spectral studies such as FTIR, UV-Vis, ¹H and ¹³C NMR spectroscopy. Gel permeation chromatography (GPC) was used to determine the molecular weight of the terpolymer. The terpolymer metal complexes were analyzed by elemental analysis, molar conductivity measurements, and magnetic susceptibilities. The structure and geometry of the metal complexes were confirmed by various spectral techniques viz. electronic, ESR, FTIR and NMR spectroscopy. The morphology of the BTF terpolymer ligand and its metal complexes was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The thermal decomposition behaviour of the terpolymer ligand and its complexes was determined using thermogravimetric analysis (TGA). Freeman–Carroll (FC), Sharp–Wentworth (SW) and Phadnis–Deshpande (PD) methods were used to calculate the thermal activation energy (E_a), order of reaction (n), entropy change (ΔS), free energy change (ΔF), apparent entropy (S*) and frequency factor (Z) from the TGA data. Phadnis–Deshpande method was also used to propose the thermal degradation model for the decomposition pattern of the terpolymer ligand. The terpolymer ligand and its metal complexes were screened for its antimicrobial activity against chosen microbes.     

Transition Metal Complexes of a Novel Polymeric Ligand: Thermal Degradation Kinetics and In Vitro Antibacterial Applications

A novel polymeric ligand poly(2-amino-3-((2-methyl-4-nitrophenylamino)methyl)benzoic acid) was synthesized using solution condensation technique in acid medium. Metal complexes were prepared using the polymer as ligand. The synthesized ligand and its metal complexes were characterized by FTIR, electronic, ESR and NMR (¹H and ¹³C) spectroscopy. The number, weight, size average molecular weights of the ligand were calculated by gel permeation chromatography. The surface morphology and the nature of the synthesized compounds were examined by SEM and XRD. The thermal behavior of the compounds was determined by thermogravimetric analysis. Thermal degradation kinetics such as activation energy (E_a), order of reaction (n) and thermodynamics viz. entropy change (ΔS), apparent entropy (S*), frequency factor (Z) and free energy change (ΔF) were also evaluated for the ligand and its metal complexes by Freeman–Carroll, Sharp–Wentworth methods. Thermal degradation mechanistic model was also proposed by Phadnis–Deshpande method. In vitro antibacterial assay was analyzed for the synthesized compounds against various pathogenic bacterial strains such as Shigella sonnei, Escherichia coli, Klebseilla species, Staphylococcus aureus, Bacillus subtilis and Salmonella typhimurium species. From the assay, the ligand and its metal complexes possess commendable antibacterial activity and hence the synthesized compounds can act as potential antibacterial agents.     

Studies of new oligomer–metal complexes and their antibacterial activities

A new oligomeric ligand was synthesized from anthranilic acid and 2‐aminopyridine with formaldehyde using a condensation technique in the presence of acid medium. Oligomer–metal complexes were prepared involving transition metal ions Cu(II), Mn(II) and Zn(II) using the synthesized oligomer as ligand. The oligomeric ligand and its metal complexes were characterized using various spectral techniques such as Fourier transform infrared, electronic, electron spin resonance, ¹H NMR and ¹³C NMR. Gel permeation chromatography was used to determine number‐, weight‐ and size‐average molecular weights of the oligomeric ligand. The surface characteristics and nature of the oligomeric ligand and its metal complexes were examined using scanning electron microscopy and X‐ray diffraction analysis. The thermal properties and degradation behaviour of the oligomeric ligand and its complexes were investigated using thermogravimetric analysis. Kinetic and thermodynamic studies of the ligand and its metal complexes were carried out using Freeman–Carroll (FC) and Sharp–Wentworth (SW) methods. From the thermogravimetric data, kinetic and thermodynamic parameters such as activation energy, order of reaction, entropy change, apparent entropy, frequency factor and free energy change were calculated. The activation energy was further calculated from the Phadnis‐Deshpande (PD) method and the degradation mechanism for the thermal decomposition reaction is proposed. The activation energy calculated from the FC and SW methods was in good agreement with that calculated from the PD method. The oligomeric ligand and its metal complexes were screened for antibacterial activity. It was found that the synthesized compounds were potent antibacterial agents. © 2012 Society of Chemical Industry     

Synthesis,characterization, and kinetic of thermal degradation of oligo‐2‐[(4‐bromophenylimino)methyl]phenol and oligomer‐metal complexes

Oligo‐2‐[(4‐bromophenylimino)methyl]phenol (OBPIMP) was synthesized from the oxidative polycondensation reaction of 2‐[(4‐bromophenylimino)methyl]phenol (BPIMP) with air and NaOCl oxidants in an aqueous alkaline medium between 50 and 90°C. The yield of OBPIMP was found to be 67 and 88% for air and NaOCl oxidants, respectively. Their structures were confirmed by elemental and spectral such as IR, ultraviolet–visible spectrophotometer (UV–vis), ¹H‐NMR, and ¹³C‐NMR analyses. The characterization was made by TG‐DTA, size exclusion chromatography, and solubility tests. The resulting complexes were characterized by electronic and IR spectral measurements, elemental analysis, AAS, and thermal studies. According to TG analyses, the weight losses of OBPIMP, and oligomer‐metal complexes with Co⁺², Ni⁺², and Cu⁺² ions were found to be 93.04%, 59.80%, 74.23%, and 59.30%, respectively, at 1000°C. Kinetic and thermodynamic parameters of these compounds investigated by Coats‐Redfern, MacCallum‐Tanner, and van Krevelen methods. The values of the apparent activation energies of thermal decomposition (E_a), the reaction order (n), preexponential factor (A), the entropy change (ΔS*), enthalpy change (ΔH*), and free energy change (ΔG*) obtained by earlier‐mentioned methods were all good in agreement with each other. It was found that the thermal stabilities of the complexes follow the order Cu(II) > Co(II) > Ni(II). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of antibacterial polychelates of urea–formaldehyde resin with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) metal ions

We studied the reaction between urea and formaldehyde with the purpose of preparing new polychelates of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. These compounds were characterized by elemental analysis, IR spectroscopy, ¹H‐NMR, electronic spectroscopy, thermogravimetric analysis (TGA), and molar conductance measurements. The percentage of metal in all of the polychelates was found to be consistent with 1:1.5 (metal/ligand) stoichiometry. The thermal behaviors of these coordination polymers were studied by TGA in a nitrogen atmosphere up to 750°C. The TGA results reveal that the complexes had higher thermal‐resistance properties compared to the common urea–formaldehyde resin. The molar conductivity and magnetic susceptibility measurements of the synthesized polychelates confirmed the geometry of the complexes. The antibacterial activity of the polychelates was also investigated with agar diffusion methods. The antibacterial activity of these polychelates was found to be reasonably good compared with standard drugs, namely, ciprofloxacin, ampicillin, and kanamycin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 928–936, 2006     

Spectral,XRD, SEM and biological properties of new mononuclear Schiff base transition metal complexes

Six new transition metal complexes derived from the reaction of 4(4-(dimethylamino) benzylideneamino) benzoic acid and Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) cations, were prepared, isolated and characterized by a range of spectral and analytical methods including UV/Vis, FT IR, NMR, MS, powder XRD, TGA and SEM. The complexes were formed with the deprotonation of the ligand and presented typical six-coordinated octahedral geometry. In addition, the biological activity was evaluated by conducting in vitro anti-bacterial, anti-fungal and anti-leishmanial screenings. All the complexes were found more active than the ligand, while complex 7 revealed biological significance.     

Synthetic,spectroscopic, magnetic,thermal, and antimicrobial approach towards new biocidal coordination polymers

O‐aminophenol was reacted with glutraldehyde to obtain Schiff base, which was then reacted with formaldehyde in slight acidic medium to generate phenolic groups. Now the substituted Schiff base was reacted with the transition metal acetates of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) to get polymeric metal complexes. Their structures have been elucidated on the basis of elemental analyses, ¹H NMR spectra, ¹³C NMR spectra, magnetic measurements, thermogravimetric analyses, electronic spectra, and infrared spectra. The results are in accordance with an octahedral environment around the central metal ion. The polychelates of Mn(II), Co(II), Ni(II), and Cu(II) are paramagnetic while Zn(II) polychelate was found to be diamagnetic. The synthesized Schiff base acted as a uninegative bidentate ligand and bonding occurs through the hydroxyl oxygen and nitrogen atoms. The thermal behavior of these coordinating polymers was studied by TGA in nitrogen atmosphere up to the temperature range of 800°C. All the synthesized polychelates were also screened for their biocidal activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis (bacteria), Candida albicans, and Muller species (yeast) by using agar well diffusion method. All the metal polychelates show promising antimicrobial activities. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124:3971–3979, 2012     

Kinetics of thermal degradation studies of some new terpolymers derived from 2,4‐dihydroxypropiophenone,oxamide, and formaldehyde

The terpolymers (2,4‐DHPOF) have been synthesized by the condensation of 2,4‐dihydroxypropiophenone with oxamide and formaldehyde in the presence of 2M HCl as catalyst with varying proportions of reactants. Terpolymer composition has been determined on the basis of their elemental analysis. The terpolymer has been characterized by UV‐visible, IR, and ¹H NMR spectra. The thermal decomposition behavior of some new terpolymers was studied using thermogravimetric analysis in air atmosphere at heating rate of 10°C/min. Thermal decomposition curves are discussed with careful attention to minute details. The Freeman–Carroll and Sharp–Wentworth methods have been used to calculate activation energy and thermal stability. Thermal activation energy (E_a) calculated with the help of these methods are in agreement with each other. Thermodynamic parameters such as free energy change (ΔF), entropy change (ΔS), apparent entropy change (S*), and frequency factor (z) are also determined on the basis of the TG curves and by using data of the Freeman–Carroll method. The Freidman method evaluated the variation in the apparent activation energy changes by isoconversional (model‐free) kinetic methods. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Biological and thermal investigations of polychelates derived from a novel terpolymer ligand

Polychelates of few transition metals were prepared using the terpolymer ligand formed from the polymerization of anthranilic acid and thiosemicarbazide with formaldehyde (ATcF). The ligand and the polychelates were characterized by elemental analysis, magnetic susceptibilities, thermogravimetric analysis (TGA), FTIR, electronic absorption and NMR spectroscopy. The metal to ligand ratio in all the polychelate was found to be 1:2. The chemical composition and structures were proposed based on various spectrometric techniques. The thermal stability of the ligand and the polychelates were determined by TGA. In addition, the activation energy for the formation of both the terpolymer ligand and its polychelates were calculated using the TGA data by Freeman-Caroll method. The surface features of the ligand and the polychelates were analyzed by scanning electron microscopy (SEM). An in vitro biological test were performed for both the ligand and its polychelates against certain pathogenic bacteria such as Escherichia coli, Klebseilla, Staphylococcus aureus, and Pseudomonas aeruginosa and fungi viz. Aspergillus flavus, Aspergillus niger, Pencillium species, Candida albicans, Cryptococcus neoformans and Mucor species.     

Preparation,characterization, and thermal properties of controllable metal–imidazole complex curing agents for epoxy resins

A series of complexes incorporating the epoxy–imidazole adduct of phenyl glycidyl ether with 2‐ethyl‐4‐methylimidazole (PGE‐EMI), has been prepared with the acetato and chloro transition metal salts of Mn, Co, Ni, Cu, Zn, and Ag. These complexes have been characterized using spectroscopic methods (IR, UV‐Vis, ¹H‐ and ¹³C‐NMR, where appropriate) and their thermal stabilities have been determined using elevated temperature NMR techniques. These high‐temperature NMR results indicated that the chloro complexes studied (of Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) exist in equilibrium (i.e., they dissociate reversibly in a solution of dimethylsulphoxide, DMSO, at elevated temperatures), while the corresponding acetato complexes dissociate irreversibly. For the silver complexes, thermogravimetric analysis (TGA) was used to monitor the dissociation, showing that the weight loss recorded was consistent with the dissociation of the metal salt to liberate the PGE–imidazole ligand. The thermal stabilities of the metal complexes were influenced by changing both the transition metal (e.g., from Mn to Zn) and varying the anion (e.g., from acetate to chloride). From ¹H‐NMR analysis, a decrease of ca. 10°C was observed in the thermal dissociation of the acetato complexes when compared with the chloro complexes, showing that the series of PGE‐EMI complexes with acetate anions is less thermally stable than the corresponding chlorides. This finding suggests that these PGE‐EMI complexes may be modified to accommodate their use in a variety of different curing schedules when used to cure epoxy resins. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 201–217, 2000     

Selective removal mercury (II) from aqueous solution using silica aerogel modified with 4-amino-5-methyl-1,2,4-triazole-3(4H)-thion

Silica aerogel surface modifications with chelating agents for adsorption/removal of metal ions have been reported in recent years. This investigation reported the preparation of silica aerogel (SA) adsorbent coupled with metal chelating ligands of 4-amino-5-methyl-1,2,4-triazole-3(4H)-thion (AMTT) and its application for selective adsorption of Hg(II) ion. The adsorbent was characterized by Fourier transform infrared spectra (FTIR) and thermo gravimetric analysis (TGA) measurements, nitrogen physisorption and scanning electron microscope (SEM). Optimal experimental conditions including pH, temperature, adsorbent dosage and contact time have been established. Langmuir and Freundlich isotherm models were applied to analyze the experimental data. The best interpretation for the experimental data given by the Langmuir isotherm equation and the maximum adsorption capacity of the modified silica gel and silica aerogel was 142.85 and 17.24mgg^?1, respectively. Thermodynamic parameters such as Gibbs free energy (ΔG ^o ), standard enthalpy (ΔH ^o ) and entropy change (ΔS ^o ) were investigated. The adsorbed Hg(II) on the SA-AMTT adsorbents could be completely eluted by 1.0M KBr solution and recycled at least four times without the loss of adsorption capacity. The results of the present investigation illustrate that modified silica aerogel with AMTT could be used as an adsorbent for the effective removal of Hg(II) ions from aqueous solution.     

Copolyperoxides of 2-(acetoacetoxy)ethyl methacrylate with methyl methacrylate and styrene; Synthesis,characterization, thermal analysis,and reactivity ratios

Copolyperoxides of 2-(acetoacetoxy)ethyl methacrylate (AEMA) with styrene (St) and methyl methacrylate (MMA) of different compositions have been synthesized in the presence of 2,2′-azobisisobutyronitrile as a free radical initiator under 100 psi oxygen pressure at 50 °C. The rates of oxidative copolymerization reactions are determined from the oxygen consumption (Δp) against time plot. Highly exothermic thermal degradations of these copolyperoxides are studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and degradation products have been characterised by electron-impact mass spectroscopy (EI-MS). The NMR spectroscopy and EI-MS analysis confirm the alternating peroxy bonds in the main chain. The monomer reactivity ratios are computed by the Fineman–Ross and Kelen–Tüdös methods, using compositions obtained from ¹H and ¹³C NMR analysis. These copolymers can potentially be used as polymeric initiators for the radical polymerization of vinyl monomers, autocombustible fuel. Also, the β-carbonyl moieties along the side chain of the copolyperoxides can be utilized to prepare degradable polyperoxide–metal complexes.     

Synthesis,crystal structure,DNA binding properties and antioxidant activities of transition metal complexes with 3-carbaldehyde-chromone semicarbazone

3-Carbaldehyde-chromone semicarbazone (L) and its Cu(II), Zn(II), Ni(II) complexes were synthesized and characterized on the basis of crystal structure and other structural characterization methods. The metal ions and Schiff base ligand can form mononuclear five-coordination complexes with 1:1 metal-to-ligand stoichiometry at the metal ions as centres. The transition metal complexes may be used as potential anticancer drugs, because they bind to calf thymus DNA via an intercalation binding mode with the binding constants at the order of magnitude 10⁵–10⁶ M^? 1, and the metal complexes present stronger DNA binding affinities than the free ligand alone. In addition, the antioxidant activities of the ligand and its metal complexes were investigated through scavenging effects for superoxide anion and hydroxyl radical in vitro, indicating that the compounds show stronger antioxidant activities than some standard antioxidants, such as mannitol and vitamin C.     

Isoconversional and thermal methods of kinetic analysis of 2,4‐dihydroxybenzophenone copolymer resin

A copolymer (2,4‐DHBPOF) synthesized by the condensation of 2,4‐dihydroxybenzophenone and oxamide with formaldehyde in the presence of acid catalyst with varying the molar proportions of the reacting monomer. Composition of the copolymer has been determined by elemental analysis. The copolymer has been characterized by UV–visible, FTIR, and ¹H NMR spectroscopy. The morphology of synthesized copolymer was studied by scanning electron microscopy (SEM). The activation energy (E_a) and thermal stability calculated by using Sharp‐Wentworth, Freeman–Carroll, and Freidman's method. Thermogravimetric analysis (TGA) data were analyzed to estimate the characteristic thermal parameters. Freeman–Carroll and Sharp Wentworth methods have been used to calculate activation energy and thermal stability. The activation energy (E_a) calculated by using the Sharp‐Wentworth has been found to be in good agreement with that calculated by Freeman–Carroll method. Thermodynamic parameters such as free energy change (ΔF), entropy change (ΔS), apparent entropy change (S*), and frequency factor (Z) have also been evaluated based on the data of Freeman–Carroll method. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Terpolymer Chelates: Synthesis,Characterization, and Biological Applications

Terpolymer ligand was synthesized from 8-hydroxyquinoline and anthranilic acid with formaldehyde (QAF) by solution condensation in an acid medium. Polychelates of Cu(II), Ni(II), Zn(II), and Pb(II) were prepared using the terpolymer as ligand. The ligand and chelates were characterized by elemental analysis, TGA, DSC, FTIR, electronic absorption, and NMR spectroscopy. The activation energy was calculated for the ligand and its polychelates formation by the Freeman-Carroll method. The ligand and its polychelates possess antimicrobial activity for certain bacteria such as Staphylococcus aureus, Escherichia coli, and fungi Aspergillus niger and Candida albicans. The surface morphology of the ligand and its polychelates was established by SEM.     

Structural studies on Cd(II) complexes incorporating di-2-pyridyl ligand and the X-ray crystal structure of the chloroform solvated DPMNPH/CdI2 complex

A series of novel Cd(II) complexes incorporating ligand, di(2-pyridinyl)methanone N-(2-pyridinyl)hydrazone (DPMNPH), has been investigated. The ligand, DPMNPH, and its corresponding complexes have been characterized with the help of a number of techniques: microanalysis, FT-IR, ¹H and ¹³C NMR, UV/vis spectroscopy, thermal studies and MS–FAB mass spectrometry. In addition, single crystal X-ray diffraction measurement studies are also employed in one of the complexes showing a distorted trigonal bipyramidal geometry. Furthermore, the existence of NH⋯Npy intramolecular hydrogen bonding interactions in the ligand and its corresponding complexes has also been reported.     

New antimicrobial polyurea: Synthesis,characterization, and antibacterial activities of polyurea‐containing thiosemicarbazide–metal complexes

A novel class of polymer–metal complexes was prepared by the condensation of a polymeric ligand with transition‐metal ions. The polymeric ligand was prepared by the addition polymerization of thiosemicarbazides with toluene 2,4‐diisocyanate in a 1 : 1 molar ratio. The polymeric ligand and its polymer–metal complexes were characterized by elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, and ¹³C‐NMR and ¹H‐NMR spectroscopy. The geometries of the central metal ions were determined by electronic spectra (UV–visible) and magnetic moment measurement. The antibacterial activities of all of the synthesized polymers were investigated against Bacillus subtilis and Staphylococcus aureus (Gram positive) and Escherichia coli and Salmonella typhi (Gram negative). These compounds showed excellent antibacterial activities against these bacteria with the spread plate method on agar plates, and the number of viable bacteria were counted after 24 h of incubation period at 37°C. The antibacterial activity results revealed that the Cu(II) chelated polyurea showed a higher antibacterial activity than the other metal‐chelated polyureas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,characterization, electrochemical behavior,thermal study and antibacterial/antifungal properties of some new zinc(II) coordination compounds

A novel symmetrical Schiff base ligand was prepared by condensation reaction of 2,2-dimethyl-1.3-diaminopropane and (E)3-(2nitrophenyl)acrylaldehyde. The ligand and its Zn(II) coordination compounds were well characterized by the elemental analysis, FTIR, ¹H, ¹³C NMR, UV–vis spectra and molar conductance. Thermal behaviors of all compounds were investigated from the room temperature to 600 °C with a heating rate of 10 °C/min. Furthermore some decomposition thermo-kinetic parameters were evaluated by Coats–Redfern equation at each decomposition step. Electrochemical properties of ligand and its complexes were studied by cyclic voltammetry technique. Also antibacterial/antifungal activities of the ligand and its complexes were tested against three Gram-negative bacteria Escherichia coli (ATCC 25922), Salmonella spp. and Pseudomonas aeruginosa (ATCC 9027) and two Gram-positive bacteria Staphylococcus aureus (ATCC 6538) and Corynebacterium renale and also three fungi (Aspergillus niger, Penicillium chrysogenum and Candida albicans). The results exhibited suitable antibacterial/antifungal properties for ligand and Zn(II) complexes. The study has shown that the complexation of ligand to zinc center lead to enhancement of antibacterial/antifungal activity.     

Synthesis,characterization, and thermal degradation studies of copolymer resin derived from p-cresol,melamine, and formaldehyde

Copolymers (p-CMF) synthesized by the condensation of p-cresol and melamine with formaldehyde in the presence of an acid catalyst and using varied molar proportion of the reacting monomers. Copolymer resin compositions were determined on the basis of their elemental analysis. The number average molecular weight of these copolymers was determined by conductometric titration in nonaqueous media. Solution viscosity measurements in dimethyl sulfoxide (DMSO) were carried out to ascertain the characteristic functions and constants of the copolymer resins. The copolymer resins were further characterized byUV–visible absorption spectra in the nonaqueous medium, Infra-red (IR) spectra, and the nuclear magnetic resonance (NMR) spectra. Thermal studies of the resins were carried out to determine their mode of decomposition, the activation energy (E_a), order of reaction (n), frequency factor (Z), entropy change (ΔS), free energy change (ΔF), and apparent entropy change (S*). Thermal decomposition curves were discussed with careful attention of minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used to calculate thermal activation energy and thermal stability. Thermal activation energy (E_a) calculated with these methods are in agreement with each other. The data from the Freeman-Carroll methods have been used to determine various thermodynamic parameters. The order of thermal stability of copolymers has been determined using TGA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,Characterization and Catalytic Activities of Palladium(II) Nitroaryl Complexes

Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (¹H, ¹³C and ³¹P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh₃, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S₁ → S₀) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts.