P RAJAKANNU
@ruraluniv.ac.in
DST-Inspire Faculty and Department of Chemistry
The Gandhigram Rural Institute
EDUCATION
M.Sc., Ph.D
RESEARCH, TEACHING, or OTHER INTERESTS
Materials Chemistry, Electronic, Optical and Magnetic Materials, Inorganic Chemistry, Organic Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Sarikalakshmi Baskaran, Keerthana Thangaraj, Vengadeshwaran Palanichamy, Bhaskaran Shankar, and Palanisamy Rajakannu
Elsevier BV
Palanisamy Rajakannu and Bhaskaran Shankar
Elsevier BV
Palanisamy Rajakannu, Woochan Lee, Sanghoon Park, Hyung Suk Kim, Hanif Mubarok, Min Hyung Lee, and Seunghyup Yoo
Wiley
Deep‐red (DR)‐to‐near‐infrared (NIR) phosphorescent organic light‐emitting diodes (OLEDs) have potentials for application in various fields ranging from phototherapy to sensing. Accordingly, herein, phenylpyridazine‐based bidentate ligands are synthesized and subsequently utilized for the preparation of dinuclear Pt(II) complexes (1–6). The molecular structures of 1–3 is investigated by single‐crystal X‐ray diffraction, and the results suggest that these complexes have substantially shortened Pt···Pt distances (2.906–2.911 Å). Complexes 1–6 exhibit intense emissions in the NIR region (700–726 nm), high photoluminescence quantum yield (PLQY) (0.11–0.18), and short phosphorescence decay lifetimes (τ = 0.64–0.95 µs) in a CH2Cl2 solution. To examine the effect of N‐substitution on the dinuclear Pt complexes, the phenylpyrimidine‐based Pt(II) emitters 7 and 8 are prepared and discovered to have Pt···Pt distances of 2.933 Å. 7 and 8 demonstrate strong emissions in the 628–650 nm range with high PLQY of 0.52–0.65. Theoretical studies indicate that the functional groups or atoms in the ligands play crucial roles in the formation of emitters with significantly shortened Pt···Pt distances. 3 and 7 are employed as non‐doped emitters to fabricate NIR OLEDs, and the resulting OLEDs exhibit electroluminescence peaks at 754 and 692 nm with maximum external quantum efficiencies of 3.0 and 4.4%, respectively.
Palanisamy Rajakannu, Hyung Suk Kim, Woochan Lee, Ajay Kumar, Min Hyung Lee, and Seunghyup Yoo
American Chemical Society (ACS)
Rigid naphthalene benzimidazole (NBI) based ligands (L1 and L2) are synthesized and utilized to make deep red phosphorescent cyclometalated iridium(III) complexes ([Ir(NBI)2(PyPzCF3)] (1) and [Ir(DPANBI)2(PyPzCF3)] (2)). Complexes 1 and 2 are prepared from the reaction of L1/L2 with the aid of ancillary ligands (PyPzCF3, 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine) in a two step method. The complexes are characterized by analytical and spectroscopic methods, as well as X-ray diffraction for 1. These complexes show a strong emission in the range of 635-700 nm that extends up to the near-infrared region (800 nm). The introduction of the diphenylamino (DPA) donor group on the naphthalene unit leads to a further red-shift in the emission. The complexes exhibit radiative quantum efficiency (ΦPL) of 0.27-0.29 in poly(methylmethacrylate) film and relatively short phosphorescence decay lifetimes (τ = 1.1-3.5 μs). The structural, electronic, and optical properties are investigated with the support of density functional theory (DFT) and time-dependent-DFT calculations. The calculation results indicate that the lowest-lying triplet (T1) excited state of 1 has a mixed metal-to-ligand charge transfer (3MLCT) and ligand-centered (3LC) character, while 2 shows a dominant 3LC character. Deep red-emitting organic light-emitting diodes fabricated using 1 as a dopant display a maximum external quantum efficiency of 10.9% with the CIE color coordinates of (0.690, 0.294), with an emission centered at 644 and 700 nm. Similarly, the emitter 2 also shows a maximum external quantum efficiency of 6.9% with emissions at 657 and 722 nm.
Sujata V. Bhat, Rohan S. Pawar, and P. Rajakannu
Bentham Science Publishers Ltd.
One-pot tandem oxidation and double Diels-Alder reaction of myrcene or ocimene with in situ generated 1,4-benzoquinone or 1,2-benzoquinone at 0°C for 1.5 h yielded polyalkylated 1,4,4a,5,8,8a,9a,10a-octahydro-9,10-anthracenediones and bis(alkylated) 9,10-phenanthrenedione respectively. The structure of novel bis-adduct from ocimene, (1R,4aR,5S,8aS,9aS,10aR)-rel- 1,4,4a,5,8,8a,9a,10a-octahydro-2,6-dimethyl-1,5-bis(3-methyl-2-buten-1-yl)-9,10-anthracenedione, was elucidated through single crystal X-ray analysis.
Palanisamy Rajakannu, Dhananjayan Kaleeswaran, Subarna Banerjee, Ray J. Butcher, and Ramaswamy Murugavel
Elsevier BV
Jia-Ling Liao, Palanisamy Rajakannu, Shih-Hung Liu, Gene-Hsiang Lee, Pi-Tai Chou, Alex K.-Y. Jen, and Yun Chi
American Chemical Society (ACS)
Functional 2-pyrazolyl-6-phenylpyridine chelates-namely, (pzpyphBu)H2 and (pzpyphCF3)H2 and phosphines-are successfully employed in the preparation of emissive Ir(III) metal complexes, for which the reaction with phosphine such as PPh3, PPh2Me, and PPh2(CH2Ph) afford corresponding Ir(III) complexes [Ir(pzpyphBu)(PPh3)2H] (1a), [Ir(pzpyphCF3)(PPh2R)2H] (2a-2c), R = Ph, Me, CH2Ph, which also show an equatorial coordinated hydride. In contrast, treatment with 1,2-bis(diphenylphosphino)benzene (dppb) and 1,2-bis(diphenylphosphino)ethane (dppe) yields the isomeric products [Ir(pzpyphBu)(dppb)H] (3a) and [Ir(pzpyphBu)(dppe)H] (3b), for which the distinctive, axial hydride undergoes rapid chlorination, forming chlorinated complexes [Ir(pzpyphBu)(dppb)Cl] (4a) and [Ir(pzpyphBu)(dppe)Cl] (4b), respectively. On the other hand, upon extensive heating of 2c, one of its coordinated PPh2(CH2Ph) exhibits benzyl cyclometalation and hydride elimination to afford [Ir(pzpyphCF3)(PPh2R)(PPh2R')] (5c and 6c) R = CH2Ph and R' = CH2( o-C6H4) as the kinetic and thermodynamic products, respectively. Their structural, photophysical, and electrochemical properties are examined and further affirmed by the computational approaches.
Palanisamy Rajakannu, Bhaskaran Shankar, and Malaichamy Sathiyendiran
Elsevier BV
Jia-Ling Liao, Palanisamy Rajakannu, Premkumar Gnanasekaran, Shang-Ru Tsai, Chun-Han Lin, Shih-Hung Liu, Chih-Hao Chang, Gene-Hsiang Lee, Pi-Tai Chou, Zhong-Ning Chen,et al.
Wiley
A series of novel diiridium complexes (1–4) bearing both functional 2‐pyrazolyl‐6‐phenyl pyridine chelate and bidentate phenyl imidazolylidene chelate are synthesized, for which the pyrazolate fragment of the tridentate 2‐pyrazolyl‐6‐phenyl pyridine also behaves as the bridge to hold two iridium atoms in close vicinity. Their structure is unambiguously confirmed using X‐ray structure determination on the corresponding derivative 2a bearing 1,3‐bis(4‐fluorophenyl)‐1H‐Imidazolyl cyclometalate. Their photophysical and electrochemical properties are studied and further affirmed by the computational approaches. All these Ir(III) metal complexes 1–4 are very stable in both solution and solid film with near unity emission quantum efficiency. As opposed to most of diiridium complexes documented in literature, 1–4 are volatile and suitable for fabrication of organic light emitting diodes (OLEDs) under vacuum evaporation. The corresponding electroluminescent devices exhibit superior performance, among which external quantum efficiency of 27.6% using 2 as dopant stands for the record high of OLEDs using dinuclear Ir(III) complexes. They also offer a low roll‐off at high luminance, demonstrating their potential en route to high performance OLEDs.
Yun Chi, Ting-Kuang Chang, Paramaguru Ganesan, and Palanisamy Rajakannu
Elsevier BV
Shankar Deval Sathiyashivan, Bhaskaran Shankar, Palanisamy Rajakannu, Pratap Vishnoi, Dhanraj T. Masram, and Malaichamy Sathiyendiran
Royal Society of Chemistry (RSC)
A family of tripodal molecules (1–6) with/without steric ethyl groups at the central benzene scaffold and with furan/thiophene/pyridyl groups at the 2-position of the benzimidazolyl unit was synthesised.
K. Garg, E. Ganapathi, P. Rajakannu, and M. Ravikanth
Royal Society of Chemistry (RSC)
We have successfully separated and characterized E- and Z-isomers of diphenyldipyrroethene molecules and studies show that the E-isomer behaves as AIEgen, whereas the Z-isomer behaves as CIEgen.
Sylvia Fernandes, P. Rajakannu, and Sujata V. Bhat
Royal Society of Chemistry (RSC)
Tandem Knoevenagel-cycloaddition reactions forming bicyclic tetrahydro-2H-chromen-5(6H)-ones and tricyclic octahydro-2H-benzo[c]-chromen-1(6H)-ones are achieved with up to 98.8% ee in the presence of chiral LBA and titanium-isopropoxy-(S)-BINOLate.
Avanish Dvivedi, Palanisamy Rajakannu, and Mangalampalli Ravikanth
Royal Society of Chemistry (RSC)
meso-Salicylaldehyde substituted BODIPY 3 was synthesized by a simple method and used as a chemodosimetric sensor for CN− anions.
Mitta Nageswar Rao, Meera Haridas, Manoj Kumar Gangwar, Palanisamy Rajakannu, Alok Ch. Kalita, and Prasenjit Ghosh
Wiley
A series of nickel-based chiral bifunctional catalysts (1d–3d) with N-heterocyclic carbene (NHC) ligands derived from (1R)-(–)-menthol, (1S)-(–)pinene, and (1R)-(+)-camphor have been successfully designed for asymmetric Michael addition reactions under base-free conditions. The NHC complexes, namely, [1-R-3-{N-(phenylacetamido)}imidazol-2-ylidene]2Ni [R = (1S)-menthyl (1d), (1S)-pinane (2d), and (1R)-isobornyl (3d)], bearing chiral ancillaries on the amido-functionalized side arms of the NHC ligands, performed the bifunctional catalysis of the asymmetric base-free Michael addition reaction of the α-methyl cyano ester substrates ethyl 2-cyanopropanoate (4), isopropyl 2-cyanopropanoate (5), and tert-butyl 2-cyanopropanoate (6) with the activated olefinic substrates methyl vinyl ketone (7) and acrylonitrile (8) in 63–98 % yields with enantiomeric excess (ee) values of 2–75 % at room temperature in 8 h. More interestingly, only the longest of the three catalysts, the menthol derivative 1d, showed significant chiral induction of up to 75 % ee; this has been attributed to the reduction of the steric influence owing to the relatively distant dispositions of the chiral ancillaries from the catalytically active metal center that arise as a consequence of the cis geometries of 1d–3d.
Palanisamy Rajakannu, Rana Howlader, Alok Ch. Kalita, Raymond J. Butcher, and Ramaswamy Murugavel
Royal Society of Chemistry (RSC)
Uncoordinated N-donors spacers in the title compounds facilitate interesting orthogonal H-bonding, leading to the formation of 3-D polymeric networks.
Palanisamy Rajakannu, Shaikh M. Mobin, and Malaichamy Sathiyendiran
Elsevier BV
Subarna Banerjee, Palanisamy Rajakannu, Raymond J. Butcher, and Ramaswamy Murugavel
Royal Society of Chemistry (RSC)
The position of benzoic acid substituents and the ability of the auxiliary ligand to act as a chelating or a bridging ligand drive metal benzoates to assemble either as discrete or as polymeric complexes.
DEEPAK GUPTA, PALANISAMY RAJAKANNU, BHASKARAN SHANKAR, FIRASAT HUSSAIN, and MALAICHAMY SATHIYENDIRAN
Springer Science and Business Media LLC
Ramasamy Pothiraja, Palanisamy Rajakannu, Pratap Vishnoi, Ray J. Butcher, and Ramaswamy Murugavel
Elsevier BV
Tejinder Kaur, Avijit Ghosh, Palanisamy Rajakannu, and Mangalampalli Ravikanth
American Chemical Society (ACS)
The hexacoordinated rhenium(I) complex of 5,10,15,20-tetra-p-tolyl-21,23-dithiaporphyrin was synthesized, and the crystal structure analysis revealed the unusual binding mode of rhenium(I) to two thiophene sulfur atoms and one of the pyrrole nitrogen atoms of the porphyrin macrocycle.
Palanisamy Rajakannu, Palani Elumalai, Bhaskaran Shankar, Firasat Hussain, and Malaichamy Sathiyendiran
Royal Society of Chemistry (RSC)
Neutral and heteroleptic metallocalix[4]arenes with covalently attached free functionalized benzimidazolyl units were synthesized using Re2(CO)10, a flexible tritopic N donor and rigid bis-chelating unit, via a one-pot process.
Palani Elumalai, Palanisamy Rajakannu, Firasat Hussain, and Malaichamy Sathiyendiran
Royal Society of Chemistry (RSC)
Arranging an aromatic cyclic trimer into a tripodal molecule was achieved by the reaction of tri(bromomethyl)benzene with substituted benzimidazoles. The edge-to-face C–H⋯π interactions in the trimer stabilize the conformation of flexible molecules.
Palanisamy Rajakannu, Palani Elumalai, Firasat Hussain, and Malaichamy Sathiyendiran
Elsevier BV
Nallasamy Palanisami, Palanisamy Rajakannu, and Ramaswamy Murugavel
Elsevier BV