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Department of Chemistry, Visva-Bharati, Santiniketan, West Bengal, India Manuscript received 21 January 1980, revised 5 September 1980, accepted 5 November 1980 The extraction of uranium from acetate solution with Versatic 10 in benzene was investigated. Uranium was quantitatively extracted at pH 5.6-5.8 from 0.1Macetic acid solution. The study included the effects of pH, extractant concentration, diluent, acetate ion concentration, ammonium sulphate concentration and contact time on the extraction of uranium. The probable composition or the extracted species was UO2R2-2HR (HR=Versatic 10). Uranium was separated from magnesium, calcium, strontium, barium, manganese, cobalt, silver, cadmium, lanthanum, cerium, praseodymium, neo-dymium, samarium, gadolinium, terbium, dysprosium, mercury, thallium, lead and thorium. Important quantitative separations or uranium from synthetic mixtures were also carried out.

Supplementary material to the article: Identification of new riboswitches and ribozymes: a multiplicity of approaches and challenges submitted to MDPI journal:Non-Coding RNA. This material include hypotheses on previoulsy discovered putative ncRNAs, updated versions of ncRNA discovery pipeline, as well as data on several putative (and confirmed) hammerhead ribozymes that have been assayed.

Department of Bioinformatics, West Bengal University of Technology, BF-142, Sector-1, Salt Lake, Kolkata-700 064, India E-mail : ban_raja@yahoo.com, banraja10@gmail.com Fax : 91-33-2334-1030 Manuscript received online 28 July 2013, accepted 11 September 2013 Naturally occurring pigment, melanins, although participate in innumerable biological functions, has not been amenable for analyses due to its heterogeneous and insoluble nature. An effort has been made here to search for a few solvents that can dissolve melanin (extracted from bacterium Azotobacter chroococcum as well as synthetic) to an appreciable amount to facilitate spectroscopic study towards its characterization. Moreover, as melanin has a high affinity for metal ions, interaction of melanins with metal ion(s) can be an avenue for enhancing the solubility of melanins in these solvents and can be utilized in various biotechnological applications.

Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India PG Department of Chemistry, University of Kashmir, Srinagar-190 006, J & K, India University Science Instrumentation Centre, University of Kashmir, Srinagar-190 006, J & K, India E-mail : muzaffar2000@gmail.com Manuscript received 12 October 2011, revised 13 February 2012, accepted 11 April 2012 Stannic silicate, a cation exchanger, has been modified by adsorption with dithizone. Adsorption behaviour of several transition and heavy metal ions like AJ3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, zn2+, Cd2+, Hg2+ and Pb2+ on the modified ion exchanger from aqueous solution at different pH (from 1-6) has been studied and their distribution coefficients (Kd) calculated. While Cd2+, Hg2+, Pb2+ and Cr3+ show very high adsorption on the modified exchanger, Fe3+ and AJ3+ are adsorbed the least among the metal ions studied. On the basis of distribution coefficients binary separations of Cd2+, Hg2+, Pb2+ and Cr3+ from Fe3+ and AJ3+ have been achieved on a chromatographic column packed with dithizone sorbed stannic silicate using nitric acid solution of pH 6 and pH 1 as eluents.

Analytical Laboratory, Department of Chemistry, Visva-Bharati, Santiniketan-731 235, West Bengal, India E-mail: bhabatosh_mandal@yahoo.co.in Manuscript received 16 October 2007, revised 12 May 2008, accepted 25 June 2008 A selective method has been developed for extraction and separation of UVI with the chemically synthesized high molecular mass crosslinked poly(acrylic acid) coated on silanized silica gel. The coated materials act as a stationary phase for the extraction chromatographic studies. The structure and thermal stability of crosslinked poly(acrylic acid) has been elucidated with the help of FTIR and TGA. The optimum pH range for quantitative extraction of uranium was found to be 4 to 6. The effects of pH and stripping agent on extraction and elution of UVI have been investigated. Ion exchange and break-through capacity of the exchanger (polymer coated on silanized silica gel) have been determined at room temperature. Surface morphology of the exchanger was studied by SEM. UVIhas been separated quantitatively from various synthetic aqueous mixtures containing metal ions (VIV, ThIV, CeIV, PbII , HgII , InIII, FeIII and ZrIV) commonly pre..,ent in uranium ores and fission products. The method permits pre-concentration and sequential separation of UVIfrom CeVI, ThIV and ZrIV of the same analytical group. A plausible mechanism for uranium ion exchange has been suggested.

Department of Chemistry, National Institute of Technology (Deemed University), Kurukshetra-136 119, India Fax: 91-1744-238050 Department of Chemistry, Meerut College, Meerut-250 00 I, India Manuscript received 19 September 2002, revised 14 July 2003, accepted 17 October 2003 Trivalent chromium, manganese and iron salts react in situ with 2,6-diacetylpyridine and 1,2-diaminobenzene to form complexes containing a 18 -membered N6 tetradentate macrocyclic ligand. The complexes are of distorted octahedral type [M(TML)]X3 , where M = CrIII, MnIIIor FeIIIand X = Cl, Br, NO3 or NCS for CrIIIand FeIII; and X= OAc for MnIII, TML = tetradentate macrocyclic ligand. The ligand coordinates through all the six nitrogen atoms. The complexes behave as 1 : 3 electrolytes and the test for anions are positive, indicate their presence outside the coordination sphere.

Department of Chemistry, University College for Women, Osmania University, Hyderabad-500 195, India E-mail : dr_saraladevich @yahoo.com Manuscript received 26 December 2002, revised 8 July 2003, accepted 12 September 2003 The FeII, CoII, NiIIand CuIIcomplexes of 2-acetonyl-2-methylbenzothiazoline (AMBT) and 2-acetyl-3-methyl-4H-1,4- benzothiazine (AM4HBT) were synthesized. The ligand AMBT underwent structural changes prior to co-ordination with metal ion. It was observed that in presence of CuIIand FeII, the AMBT oxidized to form AM4HBT in situ and then co-ordinated with the metal ions. On contrary, the ligand AMBT in presence of NiIIand CoII, converted itself to an open ring structure of Schiff base and then coordinated with the metal ions to form the corresponding complexes. To confirm these results, the complexes of FeII, CoII, NiIIand CuIIwith direct interaction from AM4HBT ligand were prepared.

Department of Chemistry, Kurushetra University, Kurukshetra-136 119, India E-mail : search@vidya.kuk.ernet.in; search@granth.kuk.ernet.in Fax : 91-01744-20277, 21639 Manuscript received 20 September 2002, revised 17 March 2003, accepted 2 April 2003 A simple, rapid, highly selective and sensitive method for the spectrophotometric determination of niobium(v) in trace amounts is presented, employing 6-chloro-2-(2'-furyl)-3-hydroxy-4-oxo-4H-1-benzopyran (CFHB) as a ligand for the complex­ation of the metal ion and extracting the 1 : 2 (M : L) coloured complex into chloroform from 4 M HCIO4 solution. Beer's law is obeyed in the range 0.32-1.25 mg ml-1 Nbv. Molar absorptivity and Sandell's sensitivity of the complex at 410 nm are 2.79 x 104 dm3 mol-1 cm -1 and 0.0033 µg Nb cm-2, respectively. The method is free from the interference of large number of elements including molybdenum, tungsten, tantalum and platinum metals. The proposed system handles the analysis of several samples of varying complexity satisfactorily

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 16 June 1999, revised 11 February 2003, accepted 12 March 2003 A simple and sensitive spectrophotometric method is developed for the determination of cobalt in aqueous DMF medium. The metal ion forms a brown coloured complex with 5-bromosalicylaldehydethiosemicarbazone (5-BSAT) in acidic medium. The complex shows absorption maximum at 410 nm. Beer's law is obeyed in the range 0.29-5.89µg ml-1 of cobalt(ll). A method for the determination of cobalt by third derivative spectrophotometry is also proposed. The methods have been employed successfully for the determination of cobalt in steel samples.

Department of Polymer Science and Technology, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata-700 009, India E-mail : sngupta@cubmb.ernet.in Fax : 91-33-3519755 Manuscript received 10 April 2001 Dithizonc complexes of CoII , ZnII, NiII and CuII have been attached to a copolymer of styrene and acrylic acid which are then crosslinked. The metal ions arc leached out leaving the ligand attached to the polymeric matrix. Absorption capacity of various metal ions in these polymeric ligands have been measured to evaluate the extent of template effect generated.

Central Laboratory, NALCO, Angul-759 145, India Department of Chemistry, Utkal University, Vani Vihar, Bhubaneswar-751 004, India Manuscript received 13 October 1998, revised 22 March 1999, accepted 23 April 1999 The proton-ligand association constant (log KH) of trans-[Co(en)2CI.glyH]2+ and trans-[Co(en)2C1.ß-alaH]2+ and the stabi­lity constants of mixed metal binuclear complexes of trans-[Co(en)2CI.glyH] 2+ and trans-[Co(en)2C1.ß-alaH]2+ with trivalent lanthanide ions have been evaluated. The proton and metal ion binding site is the unbound primary amine group of cobalt(III) substrate. Thermodynamic parameters of the complexation reaction are also presented.

Chemical Laboratories, University of Allahabad, Allahabad-211 002 Manuscript received 22 June 1990, revised 11 June 1991, accepted 12 August 1991 A Heterogeneous Precipitate based Lead(II) Coated Wire lon-selective Electrode: Its Application in the Determination of Stability Constant of 1 : 1 Lead(II)-Alizarin Red S Complex.

Chemical Laboratories, University of Allahabad, Allahabad-211 002 Manuscript received22 June 1990, revised11 June 1991, accepted12 August 1991 A Heterogeneous Precipitate based Lead(II) Coated Wire lon-selective Electrode: Its Application in the Determination of Stability Constant of 1 : 1Lead(II)-Alizarin Red S Complex.

Department of Chemistry, Visva-Bharati University, Santiniketan 731 235 Manuscript received 22 January 1990, revised 30April 1991, accepted 21 June 1991 Formation Constants of some Trivalent Rare Earth Metal Complexes with p,p'-Bromosulphono-2-hydroxy-1-naphthalldene Anil.

University Department of Chemistry, University of Poona, Pune-411 007 Manuscript received 10 March 1980, revised 1 December 1980, accepted 29 January 1981 The effect of metal ion on the dehalogenation of chloroform promoted by the ligand substitution reaction system, consisting of \({bis}\)( N-\(n\)-butyl, salim ) metal(II) [with metal(II)═Zn(II), Cu(II), Ni(II), Pt(II) and Pd(II)] and N, N, N', N' –tetramethyl-ethylenediamine has been studied. The above study of kinetics was followed by the measurement of rate of chloride release at four different temperatures. Electronegativity or the metal ion and the stereochemistry of the complex were found to control the rate of reaction. A relationship between the electronegativity of metal ion and the energy of activation has been observed. Furthermore, a relationship between the energy of activation and the downfield chemical shift of the methine proton has been obtained. These observations substantiate the nature of the proposed intermediate. The rate constant increases, and the activation energy decreases with a decrease in the electronegativity of the metal ion. It has been observed that the rate constant of dehalogenation of chloroform using a square planar complex is higher than that using a tetrahedral complex. The data of activation entropy and enthalpy changes follow the isokinetic relationship which confirms the importance of structural factors of Schiff base complexes in the dehalogenation of chloroform.

ChemicalLaboratories, University of Allahabad, Allahabad 211002 Manuscript received 8 April 1974; revised 4 October 1974; accepted 11 December 1974 Solvent Extraction of Cobalt (II) with a Mixture of Thenoyltri fluoroacetone and Ethylmethylketone in Benzene from acetate Buffers.

Chemical Laboratories, University of Allahabad, Allahabad-211 002 Manuscript received 20 April 1981, revised 3 September 1981, accepted 5 November 1981 Terephthalaldehyde \(bis\)-(isonicotinic acid hydrazone) (TBINH) has been synthesized by the condensation of terephthalaldehyde and isonicotinic acid hydrazide. TBINH yields complexes, [MLX2 .ϰH2O]n [M=Mn(II), Co(ll), N1(II), Zn(II), Cd(II), UO2(VI); L=C10 H16,N6O2; X=CH3COO-, NO\(_3^-\) and ϰ=O, 1 or 2], on reftuxing a mixture of TBINHand metal salt in DMF medium in 1 : 1 ratio. Infrared and reflectance spectra, magnetic and thermogravimetric studies indicate that the complexes are polymeric having octahedral geometry. The order of thermal stability of the polymers is: Zn>Cd>Co>Mn> UO2 >N1.

Department of Chemistry, Utkal University, Bhubaneswar-4 Manuscript received 23 May 1974; accepted 20 January 1975 The aquation of \(cis\)-oxalatoamminebis(ethylenediamine) cobalt(III) complex has been studied in the presence of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Al (III) , Ga(III), In(III), and Fe(III) ions. The oxalate bridged binuclear complexes, (en)2(NH3)CoC2O4M(n+1)+, act as the catalytically active labile intermediates in the hydrolysis reaction, the stability constants of which have been mea­sured. The catalytic activities of the metal ions vary in the order : Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II) and In(III) < Al(III)˷Ga(M) < Fe(III). The sequence k(M2+)< k(M3+)is also observed. It is presumed that the metal ion catalyzed aquation occurs with Co-Obond fission

Department of Chemistry. University of Roorkee, Roorkee (U.P.), India. Manuscript received 31 March 1976, revised 25 October 1976, accepted 24 December 1976 Studies on the Binding of Hg(II) with Casein using Mercury Electrode.

Chemistry Department, D. A. V. (P.G.) College, Dehradun (U.P) Manuscript received 9 November 1979, accepted 20 December 1979 Analytical Applications of 5-Hydroxy-1, 4-Naphthoquinone (Juglone).

Department of Chemistry, Indian Institute of Technology, Kharagpur-721 302 Materials Science Centre, Indian Institute of Technology, Kharagpur-721 301 The polymerisation of N-vinylcarbazole by 13X molecular sieves modified by five different transition metal ions, namely, MnII CoII, NiII, CuII and ZnII has been studied at a fixed metal ion incorporation. The order of reactivity follows the trend, MnII ≈ CuII > CoII > ZnII > NiII. The energy of activation has been found to decrease with decrease in pH of the exchange solution in every system. Molecular weights are characteristically high in the present system with a molecular weight distri­bution >3. The observed characteristics of the polymerisation have been explained in terms of a dual initiation mechanism involving (i) transition metal ion centre and (ii)proton sites which are generated during metal ion exchange process.

Department of Inorganic Chemistry, University of Madras, A. O. College Campus, Madras-600 026 Manuscript received 16 July 2980, accepted 5 November 1980 pH-metric investigations have been carried out on the formation of the ternary complex MAB [M=copper(II), nickel(II) or zinc(II) ion, A = iminodiacetate and B= serinate, \(\beta\)-alaninate or malonate]. The overall formation constants of the complexes have been evaluated at 30° and ionic strength of 0.2M (Na NO3). The order of stabili­ties of the complexes is found to be in keeping with the Irving-Williams order. The values of the stability constants are compared and discussed in terms of basicity, size of the chelate ring, charge neutralisation and statistical considerations. &nbsp

Rhodinm(III) trig-biguanidinium chloride ban been resolved into its optical isomers by fractional crystallisation of the diastereoisomer, rhodium tris-biguanidinium chloro(+)-tartrate. Unlike diastereoisomer, cobalt(III) tris-biguanidinium chloro(+)-tartrate, thin rhodium analogue does not exhibit any "asymmetric transformation of the second order". The lasso-gyrate forms the less soluble variety and separates first. The (— ) and 1+) enantiomers of the complex Alum (+ )-tartrate, (—)-chloride, and (—)-nitrate have been obtained in a pure state and their optical rotations have been measured. The molecular rotation of rhodium(m) tris-bigasnidinium chloro(+)-tartrate, [M]32D = ±951°, is much less than that of the corresponding cobalt complex, viz., [M]32D=±2153°. &nbsp

Ti(III& IV) ferrocyenogen complexes have been prepared by mixing the reactants in equimolecular proportions. The dried precipitates have the compositions KTiIII FeII (CN)6, Ti IV FeII. (CN)6, and TiIIIFeIII (CN)6. The freshly precipitated complexes exhibit both hydrolytic and adsorptive properties. KTiIII FeIII (CN)6 and Ti IV FeII(('N)6 hydrolyse more than TiIII FeIII(ON)6, does. Unlike other metal ferro- and ferricyanides, the metal ion is adsorbed more than the ferrocyanogen ions. Titanic ferrocyanide could be obtained as a negatively charged sol by mixing TiCl4 and K4Fe(ON)6 in the ratio of 0.89:1 respectively.

Ti(III& IV) ferrocyenogen complexes have been prepared by mixing the reactants in equimolecular proportions. The dried precipitates have the compositions KTiIIIFeII (CN)6, Ti IV FeII. (CN)6, and TiIIIFeIII (CN)6. The freshly precipitated complexes exhibit both hydrolytic and adsorptive properties. KTiIII FeIII (CN)6 and Ti IV FeII(('N)6 hydrolyse more than TiIII FeIII(ON)6, does. Unlike other metal ferro- and ferricyanides, the metal ion is adsorbed more than the ferrocyanogen ions. Titanic ferrocyanide could be obtained as a negatively charged sol by mixingTiCl4 andK4Fe(ON)6 in the ratio of 0.89:1 respectively.

For the first time the metal co-ordination polymer of thiosemicarbazone Las been synthesised. Thiosemicarbazone of naphthazarin and bivalent hexa-co-ordinating metal ions, like zinc or nickel, comprise the recurring group of the above copolymer. This group of co-ordination polymers is found to possess high thermal stability, indicated by differential thermal analysis. Unique thermal stability is shown by the zinc thiosemicarbazone of naphthazarin which starts slight decomposition at 450°.

Chemistry Department, Faculty of Science, M. S. University, Baroda-2 Manuscript received 24 May 1973; accepted 15 September 1973 Formation constants of the mixed ligand complexes, MAL, where M = Cu(II), Ni(II), Zn(II) and Cd(II); A = Histidine, Iminodiacetic acid (IMDA) or Nitrilotriacetic acid (NTA) and L = Ethyl. enediamine or Propylenediamine have been determined by using an extension of Irving-Rossotti titration technique. The values obtained for the mixed ligand formation constant KMAL are found to be-1.5 unit lower than the first formation constant KML1 in binary system. The smaller difference in \(K_{MAL}^{MA}-K_{ML1}^M\) can be explained by considering that the secondary ligand is neutral. The greater difference !in CuNTAL complexes is due to Jahn Tenor effect.

Department of Chemistry, Punjabi University, Patiala Received 23 July 1971 Ditertiaryphosphine/arsines of the type(C6H5)2E(CH2)nE(C6H5)2 (E isPor As) react with silver nitrate to yield complexes having the empirical formula, LAgNO3 .aH2O, The ir spectra indicate the presence of bidentate nitrate groups. An ionic structure having octahedral environments around silver(I) has been proposed for these complexes.However, an equilibrium. between covalent structure and ionic structure has been postulated for the complex where E is AS,t n is 4 and x is 2.

Polarograrna of Co, Ni, Zn, and Cd at various concentrations (0.0075-0.02 M) in presence of globin at pH 5.0 and at 37ºshow that the diffusion currents in presence of 1.0% globin are less than that in 0.01%, leading to the conclusion that the metal ions Form complexes with globin, the -COOH groups of which ionise between pH 2.0 and 5.5. In presence of 1.0% globin the diffusion current decreases with time and is constant after 75 minutes in case of Co, Ni, and Zn and 60 minutes in cape of Cd. The number of g. atoms of each metal combined with one g.molecule of globin has been calculated. The number of metal atoms combined with one molecule of globin is found to be 24 in the ease of Zn; 20 atoms of the bivalent metal are accounted for 40 -COOH and 4 for 8 -SH groups present in one molecule of globin. Lower values at different concentrations of other metals may be attributed to the ionisation of protein-bound metal.