Papers by Sudip Mohapatra
Inorganic chemistry, 2021
A quaternary compound, Na15Cu3Ga6S18, the first member in the A-Cu-Ga-S (A = alkali metal) series... more A quaternary compound, Na15Cu3Ga6S18, the first member in the A-Cu-Ga-S (A = alkali metal) series, has been synthesized from a solid-state metathesis reaction between Na6Ga2S6 and CuCl as well as from a combination of Na2S, Ga, Cu, and S. The compound crystallizes in a monoclinic crystal system, space group C2/c, and represents a unique open-framework structure with channels filled with eight crystallographically distinct Na ions. The anionic framework is built up of infinite chains of corner-shared GaS4 tetrahedra fused together by an edge-shared dimer of CuS4 tetrahedra forming one-dimensional ribbons of (Cu2Ga6S18)16-, which are cross-linked by linearly coordinated S-Cu-S linkages resulting in a three-dimensional network with tunnels filled with Na atoms. Optical band gap measurements show that the compound has a direct band gap of 3.00 eV that is in good agreement with the theoretical band gap derived from density functional theory calculations. Band structure calculations furth...
Journal of Solid State Chemistry
ACS Catalysis
Experimental Section General Considerations. All operations were performed under anaerobic condit... more Experimental Section General Considerations. All operations were performed under anaerobic conditions under a pure dinitrogen or argon atmosphere using Schlenk techniques on an inert gas/vacuum manifold or in a dry-box (O 2 , H 2 O < 1 ppm). Anhydrous diethyl ether, methylene chloride, acetonitrile, tetrahydrofuran, hexane, pentane, benzene, toluene, dimethylformamide, dimethylacetamide, and dimethylsulfoxide were purchased from Sigma-Aldrich. Ethanol and methanol were distilled over the corresponding magnesium alkoxide, and acetone was distilled over Drierite. Solvents were degassed by three freeze-pump-thaw cycles. Unless otherwise noted, all other reagents were purchased at the highest purity available. Potassium hydride was provided as dispersion in mineral oil and was thoroughly washed prior to use with copious amounts of tetrahydrofuran followed by hexane.
Inorganic chemistry, Jan 7, 2016
A new ternary compound with composition Cu5Sn2Te7 has been synthesized using the stoichiometric r... more A new ternary compound with composition Cu5Sn2Te7 has been synthesized using the stoichiometric reaction of Cu, Sn, and Te. The compound crystallizes in C2 space group with unit cell parameters of a = 13.549(2) Å, b = 6.0521(11) Å, c = 9.568(2) Å, and β = 98.121(2)°. Cu5Sn2Te7 is a superstructure of sphalerite and exhibits tetrahedral coordination of Cu, Sn, and Te atoms, containing a unique adamantane-like arrangement. The compound is formally mixed valent with a high electrical conductivity of 9.8 × 10(5) S m(-1) at 300 K and exhibits metallic behavior having p-type charge carriers as indicated from the positive Seebeck coefficient. Hall effect measurements further confirm holes as charge carriers with a carrier density of 1.39 × 10(21) cm(-3) and Hall mobility of 4.5 cm(2) V(-1) s(-1) at 300 K. The electronic band structure calculations indicate the presence of a finite density of states around the Fermi level and agree well with the p-type metallic conductivity. Band structure a...
Inorganica Chimica Acta, 2015
First examples of dirhenium complexes that contain bridging dithiocarbamato ligand.The electronic... more First examples of dirhenium complexes that contain bridging dithiocarbamato ligand.The electronic structure and the absorption spectra of the complexes are scrutinized.Dithiocarbamato ligands are involved both in the chelating and bridging modes.The complexes have edge-shared bioctahedral geometry.Geometry optimizations of the complexes were performed in the gas phase.Sodium salts of dimethyldithiocarbamate, diethyldithiocarbamate and pyrrolidinedithiocarbamate react with the multiply bonded paramagnetic dirhenium(III,II) complex Re2(μ-O2CCH3)Cl4(μ-dppm)2, 1 (dppm = Ph2PCH2PPh2) in refluxing ethanol to afford the paramagnetic substitution products of the type Re2(η2-S,S)2(μ-S,S)(μ-Cl)2(μ-dppm), where S,S represents the dithiocarbamato ligands [S,S = S2CNMe2, 4(LMe); S2CNEt2, 4(LEt) and S2CN(CH2)4, 4(LPyr)]. These are the first examples of dirhenium complexes that contain bridging dithiocarbamato ligand along with the dppm ligand. These complexes have very similar spectral (UV–Vis, IR, EPR) and electrochemical properties which are also reported. The identity of 4(LEt) has been established by single-crystal X-ray structure determination (Re–Re distance 2.6385 (9) Å) and is shown to have edge-shared bioctahedral structure. The electronic structure and the absorption spectra of the complexes are scrutinized by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) analyses.Dithiocarbamato bridged dirhenium(III,II) complexes with the edge-shared bioctahedral structure have been prepared and characterized by elemental analyses, IR, UV–Vis, EPR, cyclic voltammetry and by X-ray crystallography. Density functional theory and time-dependent density functional theory calculations are also reported.
Inorganica Chimica Acta, 2015
The heterogeneous phase reaction of Ru(g 2 -RL)(PPh 3 ) 2 (CO)Cl, 1 with lithium acetylacetonate ... more The heterogeneous phase reaction of Ru(g 2 -RL)(PPh 3 ) 2 (CO)Cl, 1 with lithium acetylacetonate (Liacac) afforded the complexes of the type Ru(g 1 -RL)(PPh 3 ) 2 (CO)(acac), 2 in excellent yield where g 2 -RL is C 6 H 2 O-2-CHNHC 6 H 4 R(p)-3-Me-5 and g 1 -RL is C 6 H 2 OH-2-CHNC 6 H 4 R(p)-3-Me-5 and R is H, Me, Cl.
Journal of Chemical Sciences, 2014
Two new complexes of Mn(II) and Zn(II) have been synthesized using a mixed ligand system and char... more Two new complexes of Mn(II) and Zn(II) have been synthesized using a mixed ligand system and characterized by IR spectroscopy, elemental analysis, single crystal x-ray diffraction and variable temperature magnetic study for one of the compounds. Dimeric coordination structures of [Mn 2 (2,4-pyrdc) 2 (bpe)(H 2 O) 6 ]·2H 2 O (1) and [Zn 2 (2,4-pyrdc) 2 (azpy)(H 2 O) 6 ]·2H 2 O (2) [2,4-pyrdc = 2,4pyridinedicarboxylate; bpe = 1,2-bis(4-pyridyl)ethane; azpy = 4, 4 azopyridine] are constructed by the bridging of bpe and azpy, respectively and both are extended to a 3D supramolecular structure by non-covalent interactions. In both the cases, unprecedented carboxylate(O). . . π interactions played a crucial role in the organization of the 3D supramolecular assembly. The carboxylate(O). . . π interactions are controlled by the C-H. . . π interactions which were accomplished by the proper modulation of the organic linkers. The formation of these supramolecular frameworks revealed that control of weak interactions can be achieved by the interplay of both energetically strong (covalent) and weak forces (non-covalent).
Tetrahedron, 2014
While developing bis-camphorsulfonyl urea as a hydrogen-bonding catalysts, we discovered that the... more While developing bis-camphorsulfonyl urea as a hydrogen-bonding catalysts, we discovered that the native conformation of the catalyst is unsuitable for inducing enantioselectivity. By complexing the catalyst with weakly Lewis acidic sodium cations, we were able to change the conformation of the catalyst and attain a significant improvement in the selectivity. We provide structural information from X-ray crystallography to show that the uncomplexed catalyst is indeed in an unfavorable conformation. Infrared and Raman spectroscopic studies show that sodium binds the catalyst through the carbonyl and sulfonyl groups. Simulated IR and Raman spectra match well with the experimentally recorded spectra, thereby corroborating the proposed conformational change. This result shows that weak Lewis acids can be used to tune the conformation of hydrogen-bonding catalysts and enhance the selectivity of reaction catalyzed by these systems.
Chemistry - A European Journal, 2014
We report the synthesis, structural characterization, and porous properties of two isomeric supra... more We report the synthesis, structural characterization, and porous properties of two isomeric supramolecular complexes of ([Cd(NH2 bdc)(bphz)0.5 ]⋅DMF⋅H2 O}n (NH2 bdc=2-aminobenzenedicarboxylic acid, bphz=1,2-bis(4-pyridylmethylene)hydrazine) composed of a mixed-ligand system. The first isomer, with a paddle-wheel-type Cd2 (COO)4 secondary building unit (SBU), is flexible in nature, whereas the other isomer has a rigid framework based on a μ-oxo-bridged Cd2 (μ-OCO)2 SBU. Both frameworks are two-fold interpenetrated and the pore surface is decorated with pendant -NH2 and NN functional groups. Both the frameworks are nonporous to N2 , revealed by the type II adsorption profiles. However, at 195 K, the first isomer shows an unusual double-step hysteretic CO2 adsorption profile, whereas the second isomer shows a typical type I CO2 profile. Moreover, at 195 K, both frameworks show excellent selectivity for CO2 among other gases (N2 , O2 , H2 , and Ar), which has been correlated to the specific interaction of CO2 with the -NH2 and NN functionalized pore surface. DFT calculations for the oxo-bridged isomer unveiled that the -NH2 group is the primary binding site for CO2 . The high heat of CO2 adsorption (ΔHads =37.7 kJ mol(-1) ) in the oxo-bridged isomer is realized by NH2 ⋅⋅⋅CO2 /aromatic π⋅⋅⋅CO2 and cooperative CO2 ⋅⋅⋅CO2 interactions. Further, postsynthetic modification of the -NH2 group into -NHCOCH3 in the second isomer leads to a reduced CO2 uptake with lower binding energy, which establishes the critical role of the -NH2 group for CO2 capture. The presence of basic -NH2 sites in the oxo-bridged isomer was further exploited for efficient catalytic activity in a Knoevenagel condensation reaction.
Chemistry - A European Journal, 2012
Chemistry - A European Journal, 2012
Luminescent porous materials, which combine the advantages of porosity and guest-responsive signa... more Luminescent porous materials, which combine the advantages of porosity and guest-responsive signalling (typically for gases and solvent molecules), are the solid-state analogues of the well-studied photo-functional molecular cages in solution. [1] Recently, many crystalline framework materials, for example, co-ordination polymer/metal-organic frameworks, covalent organic frameworks and periodic mesoporous silica have been constructed with chromophoric ligands, and have shown remarkable guest-induced photoelectronic properties, such as energy transfer and photoconductivity. Conversely, polymeric and self-assembled systems that can swell or gel in presence of solvent guest molecules have been used as superabsorbents. [3] Although superabsorbent materials for water uptake have already been commercialised, the design of corresponding analogues for organic solvent uptake, which are of great importance for removing organic pollutants and recovering oil from water during oil spills, [4] remains challenging because this requires selective, thermally stable and recyclable hydrophobic networks. We envisioned that an amorphous dynamic porous network with emissive backbones could provide multiple functions, such as guest/solvent-responsive swelling and signalling. In this respect, we found that organic microporous polymers with conjugated backbones are an appealing way to integrate both luminescent and dynamic functionality to the materials. Although microporous polymers have been extensively studied for gas adsorption, [8] the properties characteristic of p-conjugated segments or dynamic networks, such as signal response and solvent uptake, has not been adequately investigated to date.
Two new Cd(II) complexes 1 and 2 of two pyridine azine based ligands L1 and L2 have been synthesi... more Two new Cd(II) complexes 1 and 2 of two pyridine azine based ligands L1 and L2 have been synthesized and characterized by single crystal X-ray diffraction studies, X-ray powder diffraction studies, elemental analysis, IR and UV–VIS spectroscopy. They represent two-dimensional polymeric assemblies and 1-D chain of Cd(II) complexes depending on functionality of the ligands. Octahedral as well as tetrahedral coordination motifs of the cadmium(II) ions have been observed in the supramolecular designing of such hybrid organic–inorganic hybrid materials.► In this study we have described two Cd(II) coordination polymers of two different imino pyridyl ligands. ► We have examined the effect of change in substituents of the ligands on the nuclearity of the Cd(II) coordination polymers. ► A sterically less demanding hydrogen atom substituent promotes formation of a 2-D polymer. ► The sterically bulkier and electron donating methyl substituent results in a decrease in dimensionality only to a 1-D chain. ► Octahedral as well as tetrahedral coordination motifs of the cadmium(II) ions have been observed.
Two 3D porous terbium(III) mucicate frameworks, {[Tb 2 (Mu 2− ) 3 (H 2 O) 2 ]·4H 2 O} n (1) and {... more Two 3D porous terbium(III) mucicate frameworks, {[Tb 2 (Mu 2− ) 3 (H 2 O) 2 ]·4H 2 O} n (1) and {[Tb(Mu 2− )(Ox 2− ) 0.5 (H 2 O)]·H 2 O} n (2), have been synthesized under hydrothermal conditions by changing the pH of the reaction medium. Isostructural europium(III) and seven mixed terbium(III)−europium(III) mucicates were synthesized by doping different percentages of Eu III under similar reaction conditions and unveiling different emission colors ranging from green to red under the same wavelength. Both dehydrated Tb III metal−organic frameworks exhibit selective H 2 O vapor sorption over other solvent molecules (MeOH, MeCN, and EtOH) of less polarity and bigger size and have been correlated to the highly hydrophilic pore surfaces decorated with −OH groups and O atoms from the carboxyl groups of mucicate. M etal−organic frameworks (MOFs) with open structure
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Papers by Sudip Mohapatra