New Unsymmetric Dinuclear Copper(II) Complexes of Trans-disubstituted Cyclam Derivatives: Spectral, Electrochemical, Magnetic, Catalytic, Antimicrobial, DNA Binding and Cleavage Studies

Prabu, R.,Vijayaraj, A.,Suresh, R.,Jagadish, L.,Kaviyarasan, V.,Narayanan, V. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR, UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [$Cu_2L^{1a}$] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

New Unsymmetric Dinuclear Copper(II) Complexes of Trans-disubstituted Cyclam Derivatives: Spectral, Electrochemical, Magnetic, Catalytic, Antimicrobial, DNA Binding and Cleavage Studies

R. Prabu,A. Vijayaraj,R. Suresh, L. Jagadish,V. Narayanan,L. Jagadish,V. Kaviyarasan 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR,UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [Cu2L^(1a)] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

Comparative Study of Shape Memory Alloy Reinforced Kevlar Polymer Composite in Sheet and Wire Form with Plain Kevlar Polymer Composite

R. Prabu,K. M. Kumar,R. Selvam,K. R. Vijaya Kumar 한국고분자학회 2021 폴리머 Vol.45 No.3

The main objective of this work is to investigate the effect of shape memory alloy reinforcement in Kevlar polymer composites on mechanical and low-velocity impact properties. The sheet and wire forms of shape memory alloy (SMA-nickel-titanium alloy) are used as potential reinforcements in Kevlar-reinforced polymer composite. The developed composites were analyzed for tensile and flexural behavior. The effective bonding area, referred to as core density, contributes to incremental flexural strength in the SMA sheet reinforced composites. The developed composites exhibited better impact resistance during low-velocity impact tests at different velocities, 2.80, 3.96, and 4.85 m/sec, and simulated using a CEAST drop hammer testing machine. The impact surface of the specimen was studied on a micro-level using SEM analysis and macro-level using Image J software. The impact force, the energy absorbed, and the deformation of the specimen during impact were recorded and analyzed. The experimental results reveal that the SMA sheet reinforced Kevlar composites exhibited appreciable impact resistance with maximum energy absorbing capacity comparatively with plain Kevlar and SMA wire reinforced composites.

Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

A. Vijayaraj,R. Prabu,R. Suresh, L. Jagadish,R. Sangeetha Kumari,V. Kaviyarasan,V. Narayanan 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.11

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around −2.15 to −1.60 V The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

Vijayaraj, A.,Prabu, R.,Suresh, R.,Kumari, R. Sangeetha,Kaviyarasan, V.,Narayanan, V. Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.11

A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

Fabrication of reusable polymer nanocomposite films made of thermoplastic polyurethane and modified BiVO₄ for photodegradation of Malachite Green

R. Mohan,A. G. Jineesh,N. Manikanda Prabu 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.4

Semiconducting BiVO₄, is successfully prepared by solid-state route and attempts are taken to dope vanadium sites by titanium ions to produce BiV1-xTixO₄ (x = 5%, 10% and 15%). The products are analyzed using powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. The average particle sizes are in the range of 71-82 nm. Using diffuse reflectance spectroscopy, the band gaps are estimated and fall in visible range (2.11-2.41 eV). These nanomaterials are investigated for the photodegradation of malachite green dye solution that can find application in wastewater treatment and their efficiencies are investigated by time-dependent UV-Visible spectroscopy. 15% titanium doped BiVO₄ (BVO-15) showed the highest efficiency by completely degrading malachite green in 180 min under visible light irradiation. In such heterogenous processes, separation of the used nanocatalysts remain a challenge. To address this, reusable polymer nanocomposite films are prepared using thermoplastic polyurethane (TPU) to immobilize BVO-15. The polymer nanocomposite film with 0.10 g of catalyst in 1 g of TPU showed maximum efficiency (~ 96%). The powder and film catalysts are investigated for three cycles and found to be effective. Thus, they show remarkable photocatalytic activity, stability and reusability that make them suitable for the wastewater treatment.

Effect of Ni and Si addition on electrical, tribological and corrosion behavior of novel Cu-Zn alloy

Saravanan. R,Suresh. P,Prabu. M,Bagyalakshmi. Pd 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4

The goal of this research is to evaluate the electrical, dry sliding wear and corrosion behaviour of copper-zinc alloy reinforcedwith Ni and Si through Powder Metallurgy (P/M) technique. Six different wt. % of novel copper-zinc alloy are considered forthis research study namely 90Cu-10Zn, 88.16Cu-10Zn-1.5Ni-0.34Si, 85Cu-15Zn, 83.16Cu-15Zn-1.5Ni-0.34Si, 80Cu-20Zn and78.16Cu-20Zn-1.5Ni-0.34Si. The fabricated composites were characterized by using Scanning Electron Microscope (SEM) withEnergy Dispersive Spectroscopy (EDS) line mapping. The electrical, wear and corrosion behaviour of the fabricatedcomposites was assessed. The hardness of the fabricated composites was evaluated using Vickers Hardness Tester. Theelectrical conductivity was assessed using four-point probe tester. The result shows a significant improvement on electrical andtribological properties by increasing the wt.% of Zn, Ni and Si led of the composites. The research results concludes that78.16Cu-20Zn-1.5Ni-0.34Si composite possessed better hardness about 287 HV and the electrical conductivity about 121%IACS. The investigation result shows that Zn acts as a vital role to enhance the properties in all aspects. Also, theexperimentation results portrays that Cu-20Zn-1.5Ni-0.34Si composite possessed better specific wear rate and coefficient offriction such as 1.85 * 105 mm3/N-m and 0.29 respectively.

Investigation and optimization on micro and nano Al2O3 reinforced aluminium composites using GRA coupled PCA technique

A. Srinivasan,R. Prabu,S. Ramesh,R. Viswanathan 한양대학교 청정에너지연구소 2022 Journal of Ceramic Processing Research Vol.23 No.6

Aluminum alloy are widely adopted material for engineering applications in automobile, aircraft and marine industries. Itshigh strength to weight ratio attracts modern industry to extend its applications in various domains. For producing variouscomponents, turning is the most reputed machining operation. The method of manufacturing directly impacts the productaccuracy. The present research deals with fabrication and optimization study in dry turning of LM25 Aluminium MetalMatrix Composites (AMMCs). For AMMC fabrication, 10 wt.% of micro and nano Al2O3 ceramic particle is added asreinforcement. Hybrid Grey Relational Analysis (GRA) coupled Principal Component Analysis (PCA) technique is suggestedfor finding optimization results. Experiment was conducted with cutting speed (V), feed rate (f), and depth of cut(d) as inputparameters. Based on optimization, feed rate dominates the entire turning process compared to cutting speed and depth of cutand 12.95% improvement of GRA was achieved at the end of confirmation experiment.

Microstructure and Tribological Behaviour of Inconel-625 Superalloy Produced by Selective Laser Melting

N. Jeyaprakash,Che‑Hua Yang,G. Prabu,R. Clinktan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

This research discusses the comparative investigation of the Inconel-625 superalloy manufactured by Selective Laser Melting(SLM) process and conventional process. The fabricated component was investigated to reveal the phase transformations,microstructural features and nano-hardness. Further, wear test was conducted on specimens manufactured by both themethods as above, to study the tribological properties. XRD analysis showed that the SLM specimen has more intensity at(111) diffraction peak than the other two specimens and that the solid solution of γ-(Ni, Cr, Fe) (FCC) phases grew at (111),(2 0 0) and (220) planes. The Inconel-625 powder had lattice parameters 0.3592 nm, 0.3116 nm and 0.3012 nm, whereasthe SLM specimen possessed the lattice parameters 0.3599 nm, 0.3121 nm and 0.3012 nm which were higher than the othertwo specimens. The microstructure analysis confirmed the presence of consistent and homogeneously equiaxed cell in theconventional alloy, whereas the SLM specimen possessed heterogeneous columnar structure. Along with the columnar cell,some equiaxed and cellular cell were also formed in the SLM specimen due to remelting of the overlapped region. Moreover,the formation of equiaxed cell in XY, YZ and ZX plane directions of the conventional alloy specimen and columnar cell inthe SLM specimen was confirmed through Electron backscatter diffraction (EBSD) analysis. The SLM-produced specimenexhibited higher nano-hardness due to the formation of angular columnar cell, fine hard phases, effective bonding strengthand defect-free surface. Abrasive wear mechanism played an important role in both the samples. The wear rate of the conventionalInconel-625 alloy specimen was around 4.58 × 10–3 mm3/m while it was 1.83 × 10–3 mm3/m. The worn-out surfaceof the SLM specimen produced a lower roughness average compared with the conventional Inconel-625 specimen. Thus, theSLM technique is a promising and predominant technique to develop nickel-based superalloys for frictional applications.