Qualification: 
Ph.D, MSc, BSc
r_yamuna@cb.amrita.edu
Phone: 
+91 9894644613

Dr. Yamuna R. currently serves as Associate Professor at the Department of Sciences (Chemistry), School of Engineering, Coimbatore.

She has served as Principal Investigator for CSIR, DST, DRDO and MHRD Centre projects. Her areas of research include Liquid Crystalline Material for Fuel Cell Applications, Nano Materials, Porphyrins, Lead Acid Battery, Non Linear Optical Material. 

Dr. R. Yamuna working as an Associate Professor in Department of Sciences at Amrita Vishwa Vidyapeetham, Ettimadai campus, since August 2006.

Prior to her current position, she was working as a Lecturer in SRM University, Kattankulathur for one year. She completed her doctoral degree from Indian Institute of Technology, Kanpur. Currently, she is involved in teaching chemistry subjects for UG and PG courses. Her current research focuses on: a) Synthesis, characterization and liquid crystalline properties of cobaloximes b) Synthesis, characterization and NLO properties of porphyrin compounds c) Functionalization of Graphene oxide with organic compounds d) Photo conducting materials e) Cyclodextrin inclusion complexes for sensor applications. She completed her CSIR, DST, DRDO and MHRD projects successfully. She is guiding many M.Sc., project and Ph.D students. She has several international and national publications for her credit.

Affiliation(s)

  • Associate Professor
    Department of Sciences, Center of excellence in Advanced Materials and Green technology (CoE-AMGT)

Qualification

Year Degree/Program Institution
May, 2005 Ph. D. (Chemistry) Indian Institute of technology, Kanpur, India
1995 - 1997 MSc (Applied Chemistry)   Anna University, Chennai, India.
1992-1995 BSc (Chemistry)   RVG Govt. Arts college, chenglepet.

Experience

Year Affilliation
2014 – Present Associate Professor Department of Sciences, Amrita Vishwa Vidyapeetham 
2009-2014 Asst professor (SG) Department of Sciences, Amrita Vishwa Vidyapeetham   
2007-2009 Sr. Lecturer Department of Sciences, Amrita Vishwa Vidyapeetham
2006-2007 Lecturer Department of Sciences, Amrita Vishwa Vidyapeetham
2005-2006 Lecturer SRM Institute , Kattankulathur
2007-2010 NSS Officer, Amrita Vishwa Vidyapeetham
1998 June-1998 December Project Assistant Anna University, Chennai, India   

Awards, Certificates, Honors and Societies

  1. Member, Board of Studies, Int. MSc and MSc., Chemistry, Amrita Vishwa Vidyapeetham, 2015-2018.
  2. Reviewer for the following journals: Journal of organic chemistry (ACS), ACS Omega, Journal of Nanomaterials and molecular nano technology, Journal of nano particle research, Journal of Optical Engineering and Applications, Journal of Nanomaterials and molecular nano technology

 Membership in Professional Bodies

  1. Life Member in “Indian Society for Advancement of Materials andProcess Engineering
  2. Member in American chemical society in 2015

Awards Recognition

  1. Received Fast Track Young Scientist award from SERB-DST – 2011
  2. Institute fellowship, I.I.T. Kanpur in 1999.
  3. Senior Research Fellowship (SRF) of CSIR, New Delhi in 2002

Research Interest

  • Area of Interest
    • Interest 1: Cobaloxime containing liquid crystalline materials
    • Interest 2: non-linear optical materials
    • Interest 3: organic molecules functionalized carbon nano materials for opto-electronic applications
    • Interest 4: biologically active organic molecules
    • Interest 5: Β-cyclodextrin inclusion compounds and its sensor applications
  • Key words:
    • Cobaloxime
    • porphyrin
    • azo molecules
    • cyclodextrin
    • carbon nano materials
    • solvatochromism
    • single crystal Xrd

Research Group

Present Team

Name Title Status

Ms. G. Prabhavathi
Mesotetra (4-amino phenyl) porphyrin and azo molecules functionalized carbon nano materials: synthesis, characterization and photoluminescence properties Thesis sublitted

Mr. S. Sarath
Synthesis, characterization and liquid crystalline studies of bridged dicobaloximes  On going

Ms. Anakha
Β-cyclodextrin inclusion compounds and its sensor applications On going

Past Team

Name Title Status

Dr. M. Umadevi
Crystal Structure Determination of Some Biologically Important Molecules 2016, Completed

Master's Students

Name Title Status
Alifia C. Jafer Synthesis, characterization and linear optical properties of nickel complex of 5, 10, 15, 20-meso-tetra(4-aminophenyl) porphyrin functionalized with multi-walled carbon nanotubes Completed
Sriram Menon Synthesis and characterization of novel cobaloxime with sensitizer in the axial position Completed
Ms. Anakha Covalent functionalization of single-walled carbon nanotubes with Ni (II) complexes of meso-tetra(4-aminophenyl)porphyrin and its photo physical properties Completed
Ms. Vyshnavi Covalent functionalization and characterization of Single-walled carbon nanotubes with Cu (II) complexes of meso-tetra(4-aminophenyl)porphyrin Completed

Bachelor’s Students

Name Title Status
1 batch (four students) Corrosion inhibition studies using porphyrin Completed

Funded Project

Sponsored Projects (Status)
Years Funding Agency Title of Project Amount of Grant (Rs.) Investigators Status
2009-2012 CSIR Synthesis, characterization and liquid crystalline studies of azo and Schiff base containing porphyrin complex 17 Lakhs PI: R. Yamuna, Co-PI: Sivadayanidhi &S. Asha Completed
2012-2015 DST Synthesis, characterization and liquid crystalline studies of bridged dicobaloximes 28 lakhs PI: R. Yamuna Completed
2010-2013 DRDO Development of new and efficient photo sensitizer for dye solar cell. 45 Lakhs PI:D. Kumaresan Co-PI: K. NikhilandR. Yamuna Completed
2013-17 MHRD Synthesizing and characterizing novel porphyrins with different chromophores for developing optoelectronic materials and devices 2.5 Crore One of the Co-PI in Centre Completed

Teaching

  • UG Theory:
    • B.Tech Chemistry
    • Corrosion science
    • Instrumentation techniques
    • Polymers for electronics
  • PG/Ph.D Theory
    • Concepts in inorganic chemistry
    • Coordination chemistry
    • Organometallic chemistry
    • Polymer for electronics
    • Advanced materials
    • Bio-inorganic chemistry
    • Corrosion Science
  • UG Labs
    • B.Tech lab
    • Physical chemistry lab
    • Inorganic quantitative lab
    • Inorganic qualitative lab
  • PG Labs
    • Gravimetric analysis
    • Inorganic quantitative and semi micro analysis

           

Publications

Publication Type: Journal Article

Year of Publication Title

2020

D. Prema, Thamaraiselvi, S., and Dr. Yamuna R., “Encapsulation of N-phenyl p-phenylenediamine into β-CD: Spectral, molecular modelling studies and sensor application for detecting Fe2+ ion”, Journal of Molecular Liquids, vol. 319, p. 113990, 2020.[Abstract]


Encapsulation of N-phenyl p-phenylenediamine (NPpPDA) into β-cyclodextrin (β-CD) has been investigated by various experimental techniques as well as theoretical methods. The results of PXRD, FT-IR, NMR and SEM analysis confirm the formation of inclusion complex. Significant change occurs in the fluorescence spectral intensity of inclusion complex during the addition of Fe2+ ion as compared to other metal ions. This indicates Fe2+ chemo-sensing ability of this host-guest complex. Geometrical optimization and stability of the structure have been carried out using density functional method (DFT/B3LYP) with 6-31g (d,p) basis set. The delocalisation energy of various types of bonding interactions were investigated by Natural bond orbital (NBO) analysis. Topological parameters for bonds of interacting atoms of complex C1 have been calculated and intramolecular interactions were analysed using Atoms in molecule (AIM) theory. Both experimental as well as theoretical methods suggest that the orientation 1 is more favourable structure among the proposed two orientations. NBO results confirms the presence of strong interactions between occupied orbitals of host and vacant orbitals of NPpPDA molecule which play a key role with respect to the stability of NPpPDA:β-CD complex.

More »»

2019

V. T. Veetil, Prabhavathi, G., and Dr. Yamuna R., “Covalent Functionalization and Characterization of Single-walled Carbon Nanotubes with Cu (II) Complexes of Meso-tetra(4-Aminophenyl)porphyrin”, IOP Conference Series: Materials Science and Engineering, vol. 577, p. 012091, 2019.[Abstract]


5,10,15,20-tetra(4-aminophenyl)porphyrinatocopper(II) [CuTAP] was covalently linked via amide bond with SWCNTs. Notable changes in the FT-IR spectra reveal the covalent linking of the porphyrin chromophore with SWCNTs. Further, covalent functionalization was confirmed by the hypsochromic shift of this nano-hybrid in the UV-visible spectra as compared to that of pristine CuTAP. 38 % weight loss observed in the TGA due to the extent of Cu-TAP functionalization. Morphology study of this nano-hybrid reveals the tubular structure, which is retained even after covalent functionalization. SWCNT-CuTAP nano-hybrid shows the hypsochromic shift and hypochromic shift compared to reported TAP or Zn-TAP due to Cu metal ion substitution.

More »»

2018

A. C. Jafer, Veetil, V. T., Prabhavathi, G., and Dr. Yamuna R., “Covalent functionalization and characterization of multi-walled carbon nanotubes using 5, 10, 15, 20-tetra(4-aminophenyl)porphyrinatonickel(II)”, Fullerenes, Nanotubes and Carbon Nanostructures, vol. 26, pp. 739-745, 2018.[Abstract]


Abstract5,10,15,20-tetra(4-aminophenyl)porphyrinatonickel(II) was covalently connected to multi-walled carbon nanotube (MWCNT) through an amide linkage and characterized by using many spectroscopic techniques. In FT-IR, the carbonyl peak (C = O) of MWCNT-NiTAP is shifted to higher frequency as compared to the reported MWCNT-TAP due to Ni ion substitution. Notable changes in the FT-IR and XP spectra confirms the covalent functionalization of Ni-TAP with MWCNTs. Raman spectra indicate that the ID/IG ratio is less for MWCNT-NiTAP as compared to MWCNT, MWCNT-COOH, MWCNT-ZnTAP and MWCNT-CuTAP which is due to improved electronic properties of MWCNT-NiTAP. TGA plots of MWCNT-NiTAP reveals that ∼30% weight loss in the temperature range of 150–800 °C. Considerable shift in the absorption and emission spectra of the nano hybrid clearly indicate different electronic interaction between porphyrin and MWCNT due to nickel ion substitution. PL spectra of MWCNT-NiTAP exhibited fluorescence quenching of Ni-TAP Soret band by MWCNTs. This quenching is owing to the energy or electron transfer between Ni-TAP and MWCNTs.

More »»

2018

G. Prabhavathi, Dr. Yamuna R., and Jafer, A. C., “Covalent functionalization and solubilization of multi-walled carbon nanotubes by using zinc and copper complexes of meso-tetra(4-aminophenyl) porphyrin”, Journal of Organometallic Chemistry, vol. 861, pp. 219-229, 2018.[Abstract]


Zinc (II) and copper (II) complexes of mesotetra(4-aminophenyl)porphyrin (Zn-TAP and Cu-TAP) were covalently connected to multi-walled carbon nanotube (MWCNT) through an amide linkage and characterized by using many spectroscopic techniques. Significant modification in the FT-IR and XP spectra confirms the covalent functionalization of Zn-TAP and Cu-TAP with MWCNT. Linking Zn-TAP and Cu-TAP with MWCNTs substantially improves their solubility in many solvents. TGA plots of MWCNT-ZnTAP and MWCNT-CuTAP reveal that ∼ 40 and 23 % weight loss in the temperature range of 180-800 °C, respectively. MWCNT-CuTAP shows more thermal stability compared to MWCNT-ZnTAP and also compared to the reported similar nano hybrids. Considerable shift in the absorption and emission spectra of these nano hybrids clearly indicate different electronic interaction between porphyrin and MWCNT due to metal ions substitution. PL spectra of MWCNTZnTAP exhibited fluorescence quenching of Zn-TAP Soret band by MWCNTs in various solvents. This quenching is owing to the covalent functionalization of Zn-TAP with MWCNT molecules in the nano hybrid. This further substantiates the energy or electron transfer between Zn-TAP and the MWCNTs.

More »»

2017

G. PRABHAVATHI, Arjun, M., and Dr. Yamuna R., “Synthesis, Characterization and Photoluminescence Properties of Tetra-amino Phenylporphyrin Covalently Linked to Multi-Walled Carbon Nanotubes”, Journal of Chemical Sciences, vol. 129, pp. 699-706, 2017.[Abstract]


Synthesis of a new nano hybrid of 5,10,15,20-mesotetra(4-aminophenyl) porphyrin (TAP) functionalized with multi-walled carbon nanotubes (MWCNTs) through an amide linkage is reported for the first time. This MWCNT-TAP hybrid was characterized by Raman, Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), absorption and emission spectroscopy. TGA analysis reveals that there is a ∼ 60% weight loss when heated from 150–750∘C , which is attributed to the amount of TAP molecules that were attached to MWCNTs. Electronic properties of MWCNTs were improved in the hybrid compared to raw MWCNTs as evidenced by Raman spectra. The absorption and emission spectra of TAP and nano-hybrid indicate strong positive solvatochromism with increasing solvent polarity. Fluorescence quenching of TAP in different solvents were observed in the emission spectra in the MWCNT-TAP hybrid, indicating that covalent functionalization facilitated effective energy or electron transfer from porphyrin moiety to the MWCNT. Graphical Abstract: SYNOPSIS 5,10,15,20-mesotetra(4-aminophenyl) porphyrin (TAP) was covalently functionalized with MWCNTs through an amide linkage. Fluorescence quenching of TAP by MWCNTs were observed in different solvents. The absorption and emission spectra of this nano-hybrid exhibits strong positive solvatochromism, increasing with the solvent polarity. [Figure not available: see fulltext.]. © 2017, Indian Academy of Sciences.

More »»

2016

Dr. Yamuna R., Sarath, S., Kubandiran, K., Umadevi, M., and Chakkaravarthi, G., “Synthesis, characterization and thermal studies of 1,3-bis(4-pyridyl)propane bridged dicobaloximes”, Journal of Organometallic Chemistry, vol. 811, pp. 40-47, 2016.[Abstract]


Twelve different 1,3 bis(4-pyridyl)propane (dpyp)-bridged dicobaloximes of the type [RCo(dmgH)2]2-μ-1,3-bis(4-pyridyl)propane where R = Me - octyl (1a-8a), decyl (9a), dodecyl (10a), tetradecyl (11a), 1-chlorohexyl (12a) have been synthesized from their corresponding aqua complexes. All the synthesized cobaloximes have been characterized by 1H, and 13C Nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, UV-visible (UV-Vis) and FT-IR spectroscopy. The X-ray structures of 2a and 8a are reported. Thermal stability of these complexes has been studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Differential scanning calorimetry (DSC) study reveals that there is a mesophase in these ligand-bridged dicobaloximes with higher alkyl chains. These dpyp-bridged complexes are significant due to the flexible spacer of dpyp in between two cobaltmetallobicycles which influence extensive intermolecular C-H⋯O interactions in the crystal packing diagram of the structures 2a and 8a. The mesophase formation for these complexes strongly depends on the length of the alkyl chain (axial R group). © 2016 Elsevier B.V. All rights reserved. More »»

2015

M. Umadevi, Raju, P., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “Crystal structure of (E)-diethyl 2-[(1-phenylsulfonyl-1H-indol-3-yl)methylidene]succinate”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o1029-o1030, 2015.[Abstract]


In the title compound, C23H2 3NO6S, the phenyl ring is perpendicular [dihedral angle = 89.34(9)°] to the indole ring system. In the molecule, the ethoxy groups are each disordered over two sets of sites with occupancy ratios of 0.671(6):0.329(6) and 0.75(3):0.25(3). The molecular conformation is consolidated by a weak C - H⋯O interaction, which generates an S(6) graph-set motif. The packing of the molecules in the crystal structure features weak C - H⋯π interactions.

More »»

2015

Mab Umadevi, Raju, Pc, Dr. Yamuna R., Mohanakrishnan, A. Kc, and Chakkaravarthi, Ge, “Crystal structure of 2-[2-phenyl-1-(phenylsulfonyl)ethyl]-1-phenylsulfonyl-1H-indole”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o910-o911, 2015.[Abstract]


In the title compound, C28H2 3NO4S2, the indole ring system (r.m.s. deviation = 0.007Å) subtends dihedral angles of 78.69(13) and 38.97(13)° with the planes of the N- and C-bonded sulfonylbenzene rings, respectively, and these two benzene rings are inclined to each other at an angle of 65.45(16)°. The methylene-linked phenyl ring is twisted at an angle of 81.80(13)° from the indole ring. The molecular structure features two short intramolecular C - H⋯O contacts, which both generate S(6) rings. In the crystal, molecules are linked by C - H⋯O hydrogen bonds and C - H⋯π interactions, generating a three-dimensional network.

More »»

2015

U. M., P., R., Dr. Yamuna R., A.K., M., and G., C., “Crystal structure of 3-(2-nitrophenyl)-1-(1-phenylsulfonyl-1H-indol-3-yl)propan-1-one”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o892-o893, 2015.[Abstract]


In the title compound, C23H18N2O5S, the phenyl and benzene rings subtend dihedral angles of 78.18 (10) and 30.18 (9)°, respectively, with the indole ring system (r.m.s. deviation = 0.022 Å). The crystal structure features weak C - H⋯O and C - H⋯π interactions, which link the molecules into a three-dimensional network. More »»

2015

U. M., P., R., Dr. Yamuna R., A.K., M., and G., C., “Crystal structure of (E)-2-(4-methoxystyryl)-3-methyl-1-phenylsulfonyl-1H-indole”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o723-o724, 2015.[Abstract]


In the title compound, C24H21NO3S, the dihedral angles between the indole ring system (r.m.s. deviation = 0.030Å) and the sulfur and ethylene-bonded benzene rings are 80.2(2) and 49.29(15)°, respectively. The dihedral angle between the pendant benzene rings is 37.7(2)°. In the crystal, molecules are linked by C - H⋯O hydrogen bonds and weak C - H⋯π and π-π [centroid-to-centroid distances = 3.549(2) and 3.743(3)Å] interactions, forming a three-dimensional network. © 2015.

More »»

2015

U. M., P., R., Dr. Yamuna R., A.K., M., and G., C., “Crystal structure of N-[3-bromo-1-(phenylsulfonyl)-1H-indol-2-yl]methylbenzenesulfonamide”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o756-o757, 2015.[Abstract]


In the title compound, C21H17BrN2O4S2, the indole ring system subtends dihedral angles of 85.96(13) and 9.62(16)° with the planes of the N- and C-bonded benzene rings, respectively. The dihedral angles between the benzene rings is 88.05(17)°. The molecular conformation is stabilized by intramolecular N - H⋯O and C - H⋯O hydrogen bonds and an aromatic π-π stacking [centroid-to-centroid distance = 3.503(2)Å] interaction. In the crystal, short Br⋯O [2.9888(18)Å] contacts link the molecules into [010] chains. The chains are cross-linked by weak C - H⋯π interactions, forming a three-dimensional network. © 2015.

More »»

2015

Dr. Yamuna R., Chakkaravarthi, G., Mohanakrishnan, A. K., Raju, P., and Umadevi, M., “Crystal structure of ethyl 2-phenyl-9-phenylsulfonyl-9H-carbazole-3-carboxylate”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, no. 10, pp. o725-o726, 2015.[Abstract]


In the title compound, C27H21NO4S, the dihedral angles between the carbazole ring system (rms deviation= 0.015 Å) and the sulfur-bonded and directly linked benzene rings are 79.98 (11) and 53.51 (18)°, respectively. The benzene rings subtend a dihedral angle of 48.4 (2)°. The ethyl side chain of the ester group has an extended conformation [C—O—C— C=− 172.3 (3)°]. In the crystal, inversion dimers linked by pairs of weak C—H⋯ O hydrogen bonds generate R22 (22) loops. The dimers are linked by weak C—H⋯ π and π–π More »»

2015

M. Umadevi, Saravanan, V., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “Crystal structure of [2-methyl-1-(phenylsulfonyl)-1H-indol-3-yl](phenyl) methanone”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. 133–135, 2015.[Abstract]


In the title compound, C22H17NO3S, the sulfonyl-bound phenyl ring is almost orthogonal to the indole ring system, making a dihedral angle of 84.89 (7)°. The carbonyl-bound phenyl ring forms a dihedral angle of 57.32 (5)° with the indole ring system. The two phenyl rings are inclined at 52.68 (7)°. The S atom has a distorted tetra­hedral configuration. In the crystal, weak C-H...O inter­actions link the mol­ecules, forming a helical chain along the b-axis direction.

More »»

2015

M. Umadevi, Saravanan, V., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “Crystal structure of (2-bromomethyl-1-phenylsulfonyl-1H-indol-3-yl)(phenyl) methanone”, Acta Crystallographica Section E: Crystallographic Communications, vol. 71, pp. o86–o87, 2015.[Abstract]


In the title compound, C22H16BrNO3S, the phenyl rings make dihedral angles of 84.81 (16) and 61.67 (17)° with the indole ring system (r.m.s. deviation = 0.012 Å), while the phenyl rings are inclined to one another by 69.5 (2)°. The mol­ecular structure is stabilized by weak intra­molecular C-H...O hydrogen bonds. The sulfonyl S atom has a distorted tetra­hedral configuration. In the crystal, there are no significant inter­molecular inter­actions present.

More »»

2014

M. Umadevi, Ramalingam, B. M., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “Crystal structure of 2-(2,4-di\-chloro\-phen\-yl)-4-hydroxy-9-phenyl\-sulfonyl-9\it H-carbazole-3-carbaldehyde”, Acta Crystallographica Section E, vol. 70, pp. 466–468, 2014.[Abstract]


In the title compound, C$\sb 25$H$\sb 15$Cl$\sb 2$NO$\sb 4$S, the di\-chloro\-phenyl ring is twisted by 68.69(11)$^\circ$ from the mean plane of the carbazole ring system [r.m.s. deviation = 0.084(2)$^\circ$]. The hy\-droxy group is involved in an intra\-molecular O–-H$\cdots$O hydrogen bond, which generates an \it S(6) graph-set motif. In the crystal, pairs of C–-H$\cdots$Cl hydrogen bonds link mol\-ecules into inversion dimers with an \it R$\sp 2$$\sb 2$(26) motif. Weak C–-H$\cdots$O inter\-actions further link these dimers into ribbons propagating in [100].

More »»

2014

Dr. Yamuna R., Devi, R., Prabhavathy, G., Ramakrishnan, S., and Kothurkar, N. K., “Azo Functionalized Graphene Oxide: Synthesis Characterization and Photoluminescence Property”, Journal of chemical sciences, vol. 126, 2014.

2014

R. DEVI, PRABHAVATHI, G., Dr. Yamuna R., Ramakrishnan, S., and KOTHURKAR, N. I. K. H. I. L. K., “Synthesis, characterization and photoluminescence properties of graphene oxide functionalized with azo molecules”, Journal of Chemical Sciences, vol. 126, pp. 75–83, 2014.[Abstract]


Two different azo molecules functionalized graphene oxide (GO) through an ester linkage have been synthesized for the first time. Chemical structure of the azo-GO hybrids was confirmed by Fourier transform infrared spectroscopy and UV-visible spectroscopy. The GO functionalized with 5-((4-methoxyphenyl)azo)-salicylaldehyde was further characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The SEM studies demonstrated that the morphology of the azo-GO hybrid was found to be similar to the GO sheets but slightly more wrinkled. Further, TEM image of azo-GO indicates some dark spots on the GO sheets due to azo functionalization. AFM results also reveal that the azo functionalization increases the thickness of GO sheet to 4–5 nm from 1.2–1.8 nm. Both the azo-hybrids show absorption band around 379 nm due to the $π$–$π$* transition of the trans azo units. Photoluminescence spectra of azo-GO hybrids show a strong quenching compared with azo molecules due to the photoinduced electron or energy transfer from the azo chromophore to the GO sheets. It also reveals strong electronic interaction between azo and GO sheets. More »»

2013

Dr. Yamuna R., Ramakrishnan, Sb, Keerthy Dhara, Devi, Ra, Kothurkar, N. Kb, Kirubha, Ec, and Palanisamy, P. Kc, “Synthesis, characterization, and nonlinear optical properties of graphene oxide functionalized with tetra-amino porphyrin”, Journal of Nanoparticle Research, vol. 15, 2013.[Abstract]


The synthesis of a porphyrin-graphene oxide hybrid (GO-TAP) was carried out by covalently functionalizing graphene oxide (GO) with 5,10,15,20 mesotetra (4-aminophenyl) porphyrin (TAP) through an amide linkage. The GO-TAP hybrid has been characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible spectroscopy. The peak intensity of the Soret band of the material was suppressed compared to neat TAP. This indicates a strong interaction between the electronic energy level of TAP and GO in the GO-TAP hybrid. The functionalization of GO with TAP significantly improved its solubility and dispersion stability in organic solvents. Scanning electron micrographs reveal that the hybrid was found to be similar to the unmodified GO but slightly more wrinkled. Transmission electron micrographs also demonstrate that GO sheet in the hybrid is more wrinkled with some dark spot due to functionalization. Atomic force microscopy results also reveal that the TAP functionalization increases the thickness of GO sheet to 2.0-3.0 nm from 1.2 to 1.8 nm. We observed improved nonlinear optical and optical limiting properties for the hybrid compared to both graphene oxide and porphyrin. GO-TAP shows fluorescence quenching compared with porphyrin, indicating excellent electron and/or energy transfer to GO from TAP. Thermogravimetric analysis confirms that the GO-TAP hybrid has outstanding thermal stability. © 2013 Springer Science+Business Media Dordrecht.

More »»

2013

M. Umadevi, Saravanan, V., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “1-(2-Bromomethyl-1-phenylsulfonyl-1H-indol-3-yl) propan-1-one”, Acta Crystallographica Section E: Structure Reports Online, vol. 69, pp. o1802–o1803, 2013.

2013

M. Umadevi, Saravanan, V., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “(E)-1-[2-(4-Fluoro-2-nitrostyryl)-1-phenylsulfonyl-1H-indol-3-yl] propan-1-one”, Acta Crystallographica Section E: Structure Reports Online, vol. 69, pp. 1780–1780, 2013.[Abstract]


In the title compound, C25H19FN2O5S, the substituted phenyl ring makes a dihedral angle of 12.26 (9)° with the indole ring system. The nitro group is twisted at an angle of 26.92 (8)° out of the plane of the ring to which it is attached. The mol­ecular structure is stabilized by weak C-H...O hydrogen bonds. In the crystal, weak C-H...O, C-H...F and [pi]-[pi] [centroid-centroid distance = 3.6645 (11) Å] inter­actions link the mol­ecules, forming a three-dimensional network.

More »»

2013

M. Umadevi, Saravanan, V., Dr. Yamuna R., Mohanakrishnan, A. K., and Chakkaravarthi, G., “(Z)-3-(1-Chloroprop-1-enyl)-2-methyl-1-phenylsulfonyl-1H-indole”, Acta Crystallographica Section E: Structure Reports Online, vol. 69, no. 12, pp. o1781-o1781, 2013.[Abstract]


In the title compound, C18H16ClNO2S, the indole ring system forms a dihedral angle of 75.07 (8)° with the phenyl ring. The molecular structure is stabilized by a weak intramolecular C—H⋯ O hydrogen bond. In the crystal, molecules are linked by weak C— H⋯ O hydrogen bonds, forming a chain along [10-1]. C—H⋯ π interactions are also observed, leading to a three-dimensional network. More »»

2013

Ma Umadevi, Saravanan, Vb, Dr. Yamuna R., Mohanakrishnan, A. Kb, and Chakkaravarthi, Gd, “(E)-1-[2-(4-Chloro-2-nitrostyryl)-1-phenylsulfonyl-1H-indol-3-yl] propan-1-one”, Acta Crystallographica Section E: Structure Reports Online, vol. 69, p. o1784, 2013.[Abstract]


In the title compound, C25H19ClN2O 5S, the phenyl ring forms dihedral angles of 79.62 (12) and 80.02 (13)° with the indole ring system and the benzene ring, respectively. The nitro group is twisted at an angle of 22.39 (11)° with respect to the attached benzene ring. In the crystal, molecules assemble into double layers in the ab plane via C-H⋯O interactions.

More »»

2010

Dr. Yamuna R., ,, Chakkaravarthid, G., ,, and Saravanan, V., “biological ”, Chakkaravarthi et al.(2008, 2010)., 2010.[Abstract]


A solution of 1-(2-(bromomethyl)-1-(phenylsulfonyl)-1H-indol-3-yl) propan-1-one (5 g, 12.31 mmol) and triphenylphosphine (3.5 g, 13.54 mmol) in dry THF (100 ml) was refluxed for 6 h. After consumption of the starting material, the solvent was removed under vacuum and the solid washed with diethyl ether to give the phosphonium salt. Then, the mixture of phosphonium salt (8 g, 11.97 mmol), 4-chloro-2-nitrobenzaldehyde (2.45 g, 13.17 mmol) and K2CO3 (3.30 g, 23.95 mmol) in DCM (70 ml) was stirred at room temperature for 24 h More »»

2006

B. D. Gupta, Dr. Yamuna R., and Mandal, D., “Cobaloximes with mixed dioximes of glyoxime and diphenylglyoxime: synthesis, characterization, CV, X-ray studies, and crystal packing”, Organometallics, vol. 25, pp. 706–714, 2006.[Abstract]


Fourteen complexes of inorganic and alkyl cobaloximes with mixed dioximes of the type (R/X)Co(gH)(dpgH)Py have been synthesized and characterized by 1H and 13C NMR and UV. The spectral data are interrelated, and a good correlation is found between Δδ1H(Pyα) with δ1H(gH), δ13C(CNgH), and δ13C(CNdpgH) indicating the ring current throughout the Co(dioxime)2+ metallabicycle. All the spectroscopic data and CV show dependence on the field effect. The X-ray structure and crystal packing in ClCo(gH)(dpgH)Py, C2H5Co(gH)(dpgH)Py, and C8H17Co(gH)(dpgH)Py have been studied. ClCo(gH)(dpgH)Py shows a right-handed helix. More »»

2003

B. D. Gupta, Dr. Yamuna R., Singh, V., and Tiwari, U., “Synthesis and characterization of and cis-trans influence in cobaloximes with glyoxime as the equatorial ligand”, Organometallics, vol. 22, pp. 226–232, 2003.[Abstract]


The synthesis and characterization of RCo(gH)2Py (R = methyl through decyl) and XCo(gH)2Py (X = Cl, Br, NO2, N3) is described. Most of these complexes are new and have been synthesized for the first time. The X-ray structure of N3Co(gH)2Py is reported. The cis−trans influence has been studied by 1H and 13C NMR, UV−vis, and X-ray diffraction. For a range of X ligands, a clear trend between the 1H and 13C chemical shifts of the axial and equatorial ligands as well as with the Co-dioxime CT band has been observed. More than 20 correlations have been found. δ(13C) values for CN, Pyα, Pyβ, and Pyγ in the alkylcobaloximes always occur upfield by 1−3 ppm compared to those in the inorganic cobaloximes, and δ(13C) for CN in gH complexes occur significantly upfield, by 12−13 ppm, compared to the values in the corresponding dmgH, chgH, and dpgH complexes. More »»

2003

B. D. Gupta, Singh, V., Dr. Yamuna R., Barclay, T., and Cordes, W., “Organocobaloximes with mixed dioxime equatorial ligands: A convenient one-pot synthesis. X-ray structures and cis-trans influence studies”, Organometallics, vol. 22, pp. 2670–2678, 2003.[Abstract]


A simple and general route to the synthesis of organocobaloxime with mixed dioxime ligands, RCo(L)(dpgH)Py [L = dmgH and chgH] (R = Me-Dec), has been described. The crystal structure of four complexes, ClCo(L)(dpgH)Py and MeCo(L)(dpgH)Py [L = dmgH and chgH], is reported. The structural study reveals that both the nonclassical C−H···O as well as the classical O−H···O intermolecular hydrogen bonding is present and leads to the formation of one-dimensional dimeric or polymeric structures. 1H and 13C NMR coordination shifts in the axial pyridine ligand show clear correlations with the chemical shift of the equatorial ligand. These correlations can be rationalized with the aid of the ring current model. More »»

2001

B. Gupta, Oberoi, M., Mandal, D., Tiwari, U., Dr. Yamuna R., Vijaikanth, V., and Singh, V., “Homolytic displacements at carbon in organocobaloximes: Reactions of organocobaloximes with free radical precursor with two radical centres”, Indian Journal of Chemistry Section a-Inorganic Bio-Inorganic Physical Theoretical & Analytical Chemistry, vol. 40, pp. 986-988, 2001.[Abstract]


The reactions Of MeC6H4-SO2-SPh with organocobaloximes, RCo(dingH)(2)Py, (R = alkyl, benzyl, butenyl and allyl) under visible light photolysis show that the alkyl, butenyl and benzyl cobaloximes form the corresponding sulphides whereas the allyl cobaloximes form the organic sulphones.

More »»

2001

B. D. Gupta, Dr. Yamuna R., Singh, V., Tiwari, U., Barclay, T., and Cordes, W., “Organocobaloximes with mixed dioxime equatorial ligands: a convenient one-pot synthesis. X-ray crystal structures of BnCo III (dmgH)(dpgH) Py and BnCO III (chgH)(dpgH) py”, Journal of Organometallic Chemistry, vol. 627, pp. 80–92, 2001.[Abstract]


A simple and general route to the synthesis of organocobaloxime with mixed dioxime ligands, RCo(dmgH)(dpgH)Py and RCo(chgH)(dpgH)Py, has been described. The 13C-NMR chemical shifts have been analysed to see whether one dioxime wing has any effect on the other dioxime wing. The first crystal structure of an organocobaloxime with mixed dioxime ligand in the same complex, BnCo(dmgH)(dpgH)Py and BnCo(chgH)(dpgH)Py, is reported. More »»

2000

B. D. Gupta, Singh, V., Qanungo, K., Vijaikanth, V., Dr. Yamuna R., Barclay, T., and Cordes, W., “Organocobaloximes with mixed-dioxime equatorial ligands: a one-pot synthesis”, Journal of Organometallic Chemistry, vol. 602, no. 1-2, pp. 1 - 4, 2000.[Abstract]


BenzylCo(dmgH)(dpgH)Py has been synthesized by the reaction of benzyl chloride with a mixture of CoI(dmgH)2Py and CoI(dpgH)2Py, generated in situ, by the NaBH4 reduction of ClCo(dmgH)2Py and ClCo(dpgH)2Py. A mixture of three products is formed. The first crystal structure of an organocobaloxime with a mixed-dioxime ligand is reported. More »»

2000

B. D. Gupta, Qanungo, K., Dr. Yamuna R., Pandey, A., Tewari, U., Vijaikanth, V., Singh, V., Barclay, T., and Cordes, W., “Synthesis, characterization and cis-trans influence in cobaloximes with nioxime”, Journal of Organometallic Chemistry, vol. 608, pp. 106 - 114, 2000.[Abstract]


A synthetic scheme leading to the (X)(Y)bis(1,2-cyclohexanedionedioximato)cobalt(III) complexes, where X=Cl, N3, ClCH2, CH3, \{C2H5\} and Y=PPh3 and Py is reported. The complexes have been characterized by the usual spectroscopic techniques and have been compared with the reported analogous compounds having other dioximes as the equatorial ligands. The first crystal structure of an inorganic cobaloxime with 1,2-cyclohexanedionedioxime (Nioxime) is reported. For a range of X ligands, a clear trend between 31P, 13C, 1H chemical shifts of the equatorial and axial ligands as well as with the Co→chgH charge transfer band has been observed. More »»

Publication Type: Conference Proceedings

Year of Publication Title

2018

S. Sarath and Dr. Yamuna R., “Synthesis, Characterization and Liquid Crystalline Properties of 1,3-bis(4-pyridyl)propane connected Long Alkyl Chain Dicobaloxime”, Materials Today: Proceedings, vol. 5. pp. 16748-16755, 2018.[Abstract]


Synthesis, characterization and mesomorphic properties of dpyp-linked dicobaloxime of the kind [C15H31-CH2Co(dmgH)2]2-µ-1,3-bis(4-pyridyl)propane has been reported. This cobaloxime complex was characterized by UV-visible and Fourier Transform Infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy. Thermal properties of the complex have been studied by thermo gravimetric and differential thermal analysis. A comparative study of the mesophase formation and thermal stability of the ligand bridged dicobaloxime with long alkyl chain complexes has been reported. Liquid crystalline properties of these complexes were observed by differential scanning calorimetry and polarizing optical mircroscopy. Liquid crystalline properties of these compounds profoundly depend on the axial alkyl chain length.

More »»

2016

G. Prabhavathi, Arjun, M., and Dr. Yamuna R., “Synthesis and Characterization of Multi-Wall carbon nanotube functionalized with Meso substituted tetra-amino porphyrin”, ICNAN. VIT University, Vellore, Tamilnadu, 2016.

Publication Type: Conference Paper

Year of Publication Title

2014

Dr. Yamuna R., Ramakrishnan, S., Prabhavathi, G., and Kothurkar, N. K., “A Comparative study of porphyrin functionalized carbon nano materials”, in 1st International symposium on Nanoparticle/Nanomaterial and Applications (ISN2A), Portugal, 2014.

2011

R. Devi, Ramakrishnan, S., Keerthy Dhara, Kothurkar, N. K., and Dr. Yamuna R., “Azo functionalized graphene oxide: synthesis and characterization”, in 2nd International Conference on Advanced Nanomaterials and Nanotechnology (ICANN- 2011) , Guwahati, 2011.

2011

Keerthy Dhara, Ramakrishnan, S., Devi, R., Kothurkar, N. K., and Dr. Yamuna R., “Synthesis and Characterization of 5,10,15,20 meso tetra (4-aminophenyl) porphyrin-functionalized graphene oxide”, in 2nd International Conference on Advanced Nanomaterials and Nanotechnology(ICANN-2011), Guwahati, 2011.

2009

S. Asha and Dr. Yamuna R., “Synthesis, characterization and antimicrobial activity of cobalt(II) complexes of various alkyl substituted 2,6-Diphenyl-1-aza-7-oxa-4-spiro[2,5] octanes”, in International Conference on Coordination & Organometallic Chemistry (ICCOC-2009), Bharathiyar university, 2009.

2008

Dr. Yamuna R., “Crystal engineering in cobaloximes: Lamellar, pillared, tubular and helical assemblies assisted by C-H…O, C-H…Cl and C-H…pi interactions”, in International symposium on Structural bioinformatics: Structure and functions of macromolecules (BIOFEST-08), Ramakrishna college of arts and science , 2008.

2004

B. D. Gupta and Dr. Yamuna R., “Synthesis, Characterization and Oxygen Insertion of Cobaloximes with Glyoxime Equatorial Ligand: Novel Helical Supramolecular Structure Assisted by C-H.O Interactions”, in 6th National Symposium in Chemistry, I.I.T Kanpur, 2004.

2004

B. D. Gupta, Mandal, D., and Dr. Yamuna R., “Synthesis, Characterization and Oxygen Insertion Studies in Cobaloximes with Mesityl Glyoxime as Equatorial Ligand: X-ray Crystal Structure”, in 6th National Symposium in Chemistry, I.I.T Kanpur, 2004.

2003

B. D. Gupta and Dr. Yamuna R., “Cobaloximes with Mixed Dioxime Equatorial Ligand: Synthesis, characterization and X-ray studies ”, in 5th National Symposium in Chemistry, Chennai, 2003.

2001

B. D. Gupta, Singh, V., Dr. Yamuna R., and Tewari, U., “Alkylcobaloximes with Mixed Dioxime Equatorial Ligands: A Convenient One Pot Synthesis ”, in 3rd National Symposium in Chemistry, Panjab University, 2001.