• Ramaswamy Murugavel

      Articles written in Journal of Chemical Sciences

    • Facile one-pot synthesis of functionalized organophosphonate esters via ketone insertion into bulky arylphosphites

      Ramaswamy Murugavel Subramaniam Kuppuswamy

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      The reaction of phosphorus trichloride with 2,6-diisopropyl phenol in the presence of LiCl under reflux conditions for 24 h produces a mixture of (ArO)PCl2 and (ArO)2PCl (Ar = 2,6-𝑖Pr2C6H3). The hydrolysis of the aryloxy compounds in acetone/H2O results in the formation of two novel phosphonate ester derivatives [(ArO)P(O)(OH)(CMe2OH)] (1) and [(ArO)2P(O)(CMe2OH)] (2), respectively in a moderate yield. The title compounds have presumably formed via acetone insertion to the P-H bonds of (ArO)P(O)(H)(OH) and (ArO)2P(O)(H), respectively, in the presence of HCl produced during the hydrolysis. Compounds 1 and 2 have been characterized by elemental analysis, and ESI-mass, Infrared and NMR spectroscopic techniques. Further, solid state structures of 1 and 2 have been established by single crystals X-ray diffraction studies.

    • An anionic two-dimensional indium carboxylate framework derived from a pseudo $C_3$-symmetric semi-flexible tricarboxylic acid

      Pratap Vishnoi Alok Ch Kalita Ramaswamy Murugavel

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      Hydrothermal treatment of indium(III) nitrate with a flexible pseudo $C_3$-symmetric tricarboxylic acid at 115°C for 5 days in DMF yields a new layered anionic indium carboxylate framework, [(CH3)2 NH2)][In(L)(HCOO)(DMF)]$_n$ (1) (L = 2,4,6-tris[(4′-carboxyphenoxy)methyl]-1,3,5-trimethylbenzene), existing as two-dimensional sheets. The framework solid has been characterized by elemental analysis, FT-IR spectroscopy, TGA, PXRD and single crystal X-ray diffraction studies. DMF undergoes cleavage to dimethyl ammonium and formate ions, which are incorporated in the framework. A slipped stacking of the two dimensional sheets along 𝑎-axis in 1 results in a drastic decrease in the anticipated large porosity of the framework.

    • Sterically encumbered 2,6-dibenzhydryl-4-methylphenyl derived ligand systems: synthesis and structures


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      Bulky 2,6-dibenzhydryl-4-methylaniline, I undergoes diazotization upon treatment with H₂SO₄/NaNO₂, which upon further reaction with KI affords 1-iodo-2,6-dibenzhydryl-4-methylbenzene, 1. Reaction of I with one equivalent of acetylacetone in ethanol under reflux condition affords mono-Schiff base, 4-(2,6-dibenzhydryl-4-methylphenylamino)pent-3-ene-2-one, 2. Similarly, I reacts with half equivalent of 2-hydroxy-5-methylisophthalaldehyde or one-third equivalent of 2,4,6-trihydroxybenzene-1,3,5- tricarbaldehyde in ethanol under reflux condition to afford bis-Schiff base, 2,6-bis(((2,6-dibenzhydryl-4-methylphenyl)imino)methyl)-4-methylphenol, 3 and tris-Schiff base, 2,4,6-tris(((2,6-dibenzhydryl-4- methylphenyl)amino)methylene)cyclohexane-1,3,5-trione, 4, respectively. Further, I upon reaction with triflic acid affords (2,6-dibenzhydryl-4-methylphenyl)ammonium triflate, 5 whereas upon reaction with HBr and HCl affords co-crystals I·HBr, 6 and I·HCl, 7. All the new products were isolated in moderate to good yield and characterized by spectroscopic (IR,ESI-mass,NMR,UV-Vis) and microanalytical (CHN) techniques, in additionto a single crystal X-ray diffraction study for 1, 2 and 4-7.

    • Picric acid sensing and CO2 capture by a sterically encumbered azo-linked fluorescent triphenylbenzene based covalent organic polymer

      Dhananjayan Kaleeswaran Ramaswamy Murugavel

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      A sterically encumbered isopropyl group substituted fluorescent triphenylbenzene based azo-linkedcovalent organic polymer, iPrTAPB-Azo-COP, has been synthesized by Cu(I) catalysed homo coupling (amineamine)reaction of 1,3,5-tris(4'-amino-3'

      5'-isopropylphenyl)benzene (iPrTAPB) under aerobic conditions. TheBrunauer-Emmett-Teller (BET) and Langmuir surface areas of iPrTAPB-Azo-COP have been estimated to be395 and 697 m2 g-1 with a pore diameter of 11.6 Å. Due to the presence of fluorescent triphenylbenzeneplatform iPrTAPB-Azo-COP exhibits broad emission band centred at 428 nm, when excited at 300 nm, as aresult of extended conjugation. The inherent fluorescent nature of iPrTAPB-Azo-COP has been utilized for sensing electron-deficient polynitroaromatic compounds (PNACs) such as a picric acid (PA), dinitrotoluene (DNT), p-dinitrobenzene (p-DNB) and m-dinitrobenzene (m-DNB). Further, iPrTAPB-Azo-COP has also been utilized for capture of carbon dioxide as the azo-COP is enriched with CO2-philic nitrogen atoms apart from its microporosity. Since the azo (–N=N-) linkages are masked by the bulky isopropyl groups, iPrTAPB-Azo-COP exhibits a CO2 uptake of 6.5 and 19.4 wt% at 1 bar and 30 bar, respectively, at 273 K.

    • Synthesis, characterisation, nuclease and cytotoxic activity of phosphate-free and phosphate-containing copper 4'-(N-methylpyridinium)-2,2':6' ,2'' terpyridine complexes


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      Mononuclear Cu(II) pyridinium terpyridine based compounds, viz., [Cu(q- pytpy)(I)(CH3COO)](I)·(2H2O) (1) and [Cu(dipp)(dippH)(q-pytpy)]·(2H2O)(DMF) (2) were isolated by reacting Cu(OAc)2·H2O with 4'-(N-methylpyridinium)-2,2':6',2''-terpyridine (q-pytpy) in the presence of 2,6 diisopropylphenyl phosphate(dippH2). Both the new compounds were isolated as single crystals and characterised by spectroscopic (IR,ESI-MS, EPR, UV–Vis), thermogravimetric and microanalytical techniques. The molecular structures of both the compounds were determined in the solid-state by single crystal X-ray diffraction studies. Complexes 1 and 2 were evaluated for their nuclease and in vitro anti-tumor activities against human breast and colorectal cancer cell lines. The DNA cleavage and cytotoxic assays revealed that both 1 and 2 are effective in cleaving DNA, while the cytotoxic activity of 1 is better than 2 in both human colon and breast cancer cell lines.

    • Cyclic zinc organophosphate based expanded ditopic N,N-metalloligands


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      A new series of zinc phosphate based novel elongated ditopic N,N-metalloligands [Zn(Xdipp)(pyterpy)]2.2MeOH (X= H (1), Cl (2), Br (3), I (4)], exemplifying expanded 4,4-bipyridine spacer family, has been prepared by reacting 4-(4ꞋꞋ-pyridyl)-2,2:6,2ꞋꞋ-terpyridine (pyterpy), 2,6-iisopropylphenylphosphate (dippH2) or its para-halo functionalized derivatives X-dippH2 (X = Cl, Br, I) with Zn(OAc)2.2H2O in a mixture of solvents at room temperature. The formation of these metalloligands has been confirmed by their spectroscopic and analytical data. Solution and solid-state stability of these complexes have beenconfirmed by both mass spectroscopy and thermogravimetric analysis. The solid-state structures of 1–4 have further been established by single crystal X-ray diffraction studies, revealing that the N,N-distance in these systems can be expanded approximately to 23 A° , as against the 7 A° separation observed for 4,4-bipyridine.Compounds 2–4, which contain two pyridyl nitrogen centers and two C–X functionalities that are orthogonal to each other, could offer new possibilities in their use as metalloligand to build extended 2-D and 3-D solids

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