Manabendra Ray

Indian Institute of Technology Guwahati | IIT Guwahati · Faculty of Inorganic Chemistry

Four salts of an anionic iron(III) bis-complex, [Fe(LL-thr)2]1-, were synthesized from water or methanol. H2LL-thr is a tridentate ligand derived from the L-threonine amino acid, and the cations used are Li+ (1), Na+ (2), K+ (3), and Ba2+ (4). Single-crystal X-ray diffraction showed that all the complexes are coordination polymers of different dime...

Iron-Polyphenols are attractive as adsorbents as polyphenols are abundant in plants and tend to form high-surface-area nanoparticles with metal. However, reports on the large-scale synthesis and adsorption properties are rather limited. We are reporting a multi-gram scale synthesis of a nanostructured material from tannic acid and iron(II) salt. Ta...

Read here: https://authors.elsevier.com/a/1e4Md4x7R2YrDD Brief. AFC polymers with very different surface properties were synthesized by changing the solvent ratio. Salt forms remove chromate from water very efficiently without interference from common ions like Ca2+, Mg2+, Cl- and SO42-. Significance. AFC is a polymer that has been shown to remov...

Racemic 1-phenylethylamine was converted to bidentate Schiff base ligand by condensing with imidazole-2-carboxaldehyde (rac-L2). The reaction between Ni(II)(ClO4)2, rac-L2 and another Schiff Base S-L1 (ratio:1:2:2) yielded crystals of fac-Δ-[Ni(S-L1)2(S-L2)](ClO4)2 (1). The ligand S-L1 is a condensation product of S-1-phenylethylamine and pyridine-...

Chiral recognition is an important phenomenon. Identifying factors those influences recognition and resolution have significance in multiple areas. Earlier, we had reported recognition and resolution (30% ee) of 1-phenylethylammonium cation using an anionic binuclear Ni(II) complex of a L-histidine derived ligand. We have now synthesized its L-meth...

Removal of hexavalent chromium by aniline-formaldehyde condensate polymer coated on silica gel, in the past, showed poor removal at low concentration range with high adsorbent dose (∼30% removal at 10 mg/L with a adsorbent dose of 8 g/L). We have now synthesized a new form of the support less polymer which brings down residual concentration to less...

Chiral recognition through noncovalent interaction occurs in many biological systems. Structural characterization of chiral host–guest complexes can enhance the understanding of recognition mechanism. but such examples are relatively few. Chiral recognition and resolution of 1-phenylethylamine was studied where a binuclear Ni(II) complex acts as ch...

We are reporting structural characterization of two new hexanuclear cages (H3O)2[Cu3(μ3-OH)(μ3-NH3)0.5(L)3]2·8H2O (1) and (H3O)2[Cu3(μ3-OH)(μ3-H2O)0.5(L)3]2·8H2O (1a) where L2− is the dianionic form of the Schiff base of L-alanine and salicylaldehyde. The complex 1 has two C3 symmetric hydroxo bridged trinuclear halves joined by an ammonia or water...

a b s t r a c t Four different mononuclear octahedral Ni(II) complexes with protonated and deprotonated form of the same ligand have been synthesized by controlling reaction conditions and structurally characterized. The complexes are [Ni(HL L-his)(benzoate)(MeOH)] (1), [Ni(HL L-his)(SCN)(MeOH)] (2), [Ni(HL L-his) 2 ] (3) and [Ni(L L-his)(imidazole...

(Figure Presented) A perfect fit! The cavity of a chiral binuclear Ni II complex recognises enantiomers of amino alcohols by recognising three different groups around the chiral carbon through non-covalent interactions (see scheme). The recognised enantiomer is recoverable from the cavity by metathesis with KNO3. Optical rotation of the isolated am...

L-leucine derived ligand (H(2)L(L-leu)), KOH, and Ni(II) salt in 2:2:1 ratio self-assembled into a rather large (approximately 13 A) supramolecular assembly with the formula [K{Ni(HL(L-leu))(2)}(3)](+) (1). Structural characterization showed three [Ni(HL(L-leu))(2)] units encapsulated K(+) similar to organic crown ethers/cryptand. Substituting Ni(I...

An amine-based polymer, aniline formaldehyde condensate (AFC) was coated on silica gel and used as an adsorbent for removal of trivalent chromium [Cr(III)] in aqueous environment. A comparative study with mixed metal solutions containing Cu(II), Cd(II), Pb(II), Cr(III) and Ni(II) showed that adsorption was in the order of Cu(II) > Ni(II) > Cr(III)...

Earlier we reported the tendency of ferrocenylmethyl substituted amino acids to organize around Cu(ii) in a C(2) symmetry. In this paper we have utilized this property to form a chiral cavity using a l-tyrosine derivative. Structural characterization of [Cu(II)(S-fTyr)(2)(MeCN)(2)] (), where S-fTyr(1-) is ferrocenylmethyl-l-tyrosinate, showed that...

Aniline-formaldehyde condensate (AFC) is an amine functional group containing polymer. The sticky resinous nature of the polymer limits its usefulness. Synthesis of AFC in presence of methanol, isopropanol, t-butanol, n-octanol or glycerine formed solid cakes instead of resinous material. The scanning electron microscopic (SEM) picture of the polym...

Quinoxalines are heterocyclic compounds with potential application as drugs or fluorophores. However, few quinoxalinylium salts have been reported in the literature. This manuscript describes the synthesis and structural characterization of a previously unknown quinoxalinylium derivative, 2-aminopyrido[1,2-a]quinoxalin-11-ylium ([1](+)), as perchlo...

In the present study, short chain polyaniline (PANI), a polymer was synthesized on the surface of jute fiber and was used as an adsorbent to remove hexavalent chromium (Cr(VI)). Experiments were conducted in batch mode with the variables such as amount of jute fiber on PANI, chain length of PANI, solution pH, initial concentration of Cr(VI), dose o...

This paper reports on the synthesis, characterization and electrochemical properties of four ferrocenylmethyl substituted L-amino acid ligands and their Cu(II) complexes. Structural characterization of the complexes of L-methionine and L-asparagine derived ligands showed axial coordination of weak thioether and amide respectively to Cu(II). Coordin...

A resinous functionalized polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent to remove copper (Cu2+) from aqueous solution under conditions of different initial Cu2+ concentration, adsorbent loading, pH and adsorption time. Coordination bond formation between amine group and Cu2+ ion was the main mechanism...

This paper reports the observation of a reversible disassembly process for a previously reported octanuclear Cu(II) complex with imidazole. To identify the factors responsible for the process, five Cu(II) complexes of different nuclearity with different amino acid-derived tetradentate ligands were structurally characterized. The results show that t...

A resinous polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent in batch system for removal of hexavalent chromium from aqueous solution by considering the effects of various parameters like reaction pH, dose of AFC coated silica gel, initial Cr(VI) concentration and aniline to formaldehyde ratio in AFC synth...

A H-bond capable chiral tetradentate ligand, Fe3+, and acetate ion assembles into a hydroxo-bridged binuclear complex with the formula [FeIII2(mu-OH)(mu-OAc)(S-L)2] x 4H2O (1) where H2S-L = S-2-(2-hydroxy-benzylamino)-3-(1H-imidazol-4-yl)-propionic acid. The crystal of 1 contains right-handed one-dimensional (1D) helical channels with 7.3-9.8 A dia...

A series of diiron(II) complexes of the dinucleating ligand HPTP (N,N,N',N'-tetrakis(2-pyridylmethyl)-2-hydroxy-1,3-diaminopropane) with one or two supporting carboxylate bridges has been synthesized and characterized. The crystal structure of one member of each subset has been obtained to reveal for subset A a (micro-alkoxo)(micro-carboxylato)diir...

Copper(II) complexes of a tetradentate ligand self-assemble in pyridine to form two slightly different tetrameric units. Hydrogen bonding between the tetramers forms a capsular cavity that traps four molecules of pyridine (see picture).

Using a tridentate bis-amide ligand 2,6-bis[N-(phenyl)carbamoyl]pyridine (H2L), in its deprotonated form, two new monohydroxo-bridged dicopper(II) complexes M[Cu2L2(OH)]·2H2O (M=Na+ (1) and K+ (2)) have been prepared and characterised by a number of methods, including X-ray crystallography. Each copper(II) ion is terminally coordinated by one pyrid...

We reported the synthesis and characterization of peptide complexes of low-spin iron(III) [Fe(bpb)(py)2][ClO4] (1) and Na[Fe(bpb)(CN)2] (2) [H2bpb = 1,2-bis(pyridine-2-carboxamido)benzene; py = pyridine], where iron is coordinated to four nitrogen donors in the equatorial plane with two amide nitrogen anions and two pyridine nitrogen donors (Ray, M...

Using a bidentate ligand N-(2-chloro-6-methylphenyl)pyridine-2-carboxamide (HL5), in its deprotonated form, two new five-co-ordinate complexes of composition [M(L5)2(H2O)]·H2O (M = CoII 1 or CuII 2) have been prepared and characterized including X-ray crystallography. The co-ordination geometry at CoII and CuII is approximately trigonal bipyramidal...

Non-heme Fe(II) proteins form stable nitrosyl adducts. However, there are few synthetic examples of structurally characterized non-heme iron nitrosyl complexes, especially those that are coordinatively unsaturated. Presented herein is a series of non-heme {Fe−NO}7 complexes with trigonal bipyramidal coordination geometry. These complexes were synth...

A series of trigonal monopyramidal complexes of the tripodal ligand tris((N-tert-butylcarbamoyl)methyl)aminato, [1But]3-, have been synthesized and characterized. The structures of [Co1But]-, [Zn1But]-, and [Ni1But]- confirm that trigonal monopyramidal coordination geometry occurs in these complexes where the three amidate nitrogens are arranged in...

Two novel low-spin complexes, [Et4N][FeL2.15H(2)O (1) and [Et4N[CoL2].2H2O (2) (L is a deprotonated bis-amide ligand), have been synthesized and characterized. Four relatively longer equatorial M-N-amide bonds and two significantly shorter axial M-N-py bonds are the noteworthy features of their X-ray structures. EPR and (34-300 K) magnetic studies...

An unusual trigonal monopyramidal nickel(II) complex of a new tripodal tris-(N-tert-butylcarbamoylmethyl)aminato (3–) ligand is reported; this ligand sterically protects the NiII centre preventing further ligand coordination.

Three copper(II) complexes [CuL1]·H2O 1, [CuL22]2 and [CuL32]3[H2L1=N,N′-o-phenylenebis-(pyridine-2-carboxamide); HL2=N-phenylpyridine-2-carboxamide; HL3=N-2,4,5-trichlorophenyl-pyridine-2-carboxamide] have been prepared and their stereochemical properties investigated. Complex 2 has been characterized by X-ray crystallography: space group P21/n, a...

Mononuclear iron(III) complexes trans-[Fe(bpb)X2]+/–[H2bpb = 1,2-bis(pyridine-2-carboxamido)-benzene; X = pyridine (py)1, N3–2, MeCO2–3 or CN–4] and trans-[Fe(bpc)X2]+/–[H2bpc = 4,5-dichloro-1,2-bis(pyridine-2-carboxamido)benzene; X = py 5, Cl–6 or MeCO2–7] have been synthesised and characterized. Complexes 1 and 4 are low-spin (µeff= 2.50 and 2.10...

A series of diamagnetic cobalt(III) complexes of bpb and bpc ligands [H2bpb = 1,2-bis(2-pyridinecarboxamido)benzene; H2bpc = 4,5-dichloro-1,2-bis(2-pyridinecarboxamido) benzene] with axial ligands (Cl−, N3−, SCN−, NO2− or MeCO2−) has been synthesized. The trans geometry has been shown by 1H NMR spectroscopy. The brown or green crystalline complexes...

The synthesis and solution properties of the high-spin (µeff.= 4.78–4.86 at 298 K) manganese(III) complexes [Mn(bpb)X][X = Cl–, N3–, or SCN–; H2bpb = 1,2-bis(2-pyridinecarboxamido)benzene], are described. The brown crystalline complexes display ligand-to-metal charge-transfer transitions at ca. 430 nm, while in the near-infrared region crystal-fiel...