Santanab Giri

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Structural and theoretical investigation on two dinuclear Fe(III) complexes of tridentate NNO-donor Schiff base ligands

Polyhedron, 2014

Two new Fe(III) complexes of formulas [FeL 1 (N 3 )(OMe)] 2 (1) and [FeL 2 (N 3 )(OH)] 2 ÁH 2 O (... more Two new Fe(III) complexes of formulas [FeL 1 (N 3 )(OMe)] 2 (1) and [FeL 2 (N 3 )(OH)] 2 ÁH 2 O (2) have been synthesized by using two tridentate NNO-donor Schiff base ligands HL 1 {(2-[(3-methylaminoethylimino)-methyl]-phenol)} and HL 2 {(2-[1-(2-dimethylaminoethylimino)methyl]-phenol)}, respectively. Substitution of the -CH 3 group on the secondary amine group of the N,N-dimethyldiamine fragment of the Schiff base by a H-atom leads to a structural change from a methoxido-bridged dimer (1) to a single hydroxido-bridged dimer (2). Both complexes have been characterized by single-crystal X-ray analyses, IR and UV-Vis spectroscopy and DFT studies. Both dimers are centrosymmetric containing two Fe III atoms which are bridged by two methoxido ions in compound 1 and by two hydroxido ions in compound 2. The chelating tridentate Schiff base and a terminal azido group complete the distorted octahedral environment around each iron center in both complexes. To explain the preferential bridging ability of methoxido and hydroxido groups in complexes 1 and 2, we have carried out theoretical calculations based on DFT to compare their formation energies and dimerization energies. In the case of complex 2, it is noticed that the close proximity of the azido group from the iron centers allow the hydroxido bridged complex to gain extra stability through H-bonds, whereas due to the steric crowding of the azido group and the methyl moiety of adjacent molecules, complex 1 disfavors the formation of hydrogen bonds as well as hydroxido bridging.

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Topological Analysis to Predict the Bonding Nature of Py-nM+@H2 (Py = Pyridazine, Pyrimidine, Pyrazine and M=Li, Na, K) compounds

School of Applied Science and Humanities, Haldia Institute of Technology, Haldia 721657, India&lt... more School of Applied Science and Humanities, Haldia Institute of Technology, Haldia 721657, India Department of Chemistry, Cooch Behar Panchanan Barma University, Cooch Behar 736101, India Department of Chemical Engineering, Haldia Institute of Technology, Haldia 721657, India Energy decomposition analysis(EDA) of Py-M+ (Py = Pyridazine, Pyrimidine, Pyrazine & M=Li, Na, K) and pyrazine-2M+ (M=Li, Na, K ) building blocks have been carried out to evaluate the bonding nature after metal doping with C4H4N2(Pyridazine, Pyrimidine, Pyrazine) isomers. To show what type of interaction occurred between building blocks and adsorbed H2 molecules, a topological analysis has been performed.

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18-Electron rule inspired Zintl-like ions composed of all transition metals

Physical Chemistry Chemical Physics, 2014

Zintl phase constitutes a unique class of compounds composed of metal cations and covalently bond... more Zintl phase constitutes a unique class of compounds composed of metal cations and covalently bonded multiply charged cluster anions. Potential applications of these materials in solution chemistry and thermoelectric materials have given rise to renewed interest in the search of new Zintl ions. Up to now these are mostly composed of group 13, 14, and 15 post-transition metal elements and very few Zintl ions composed of all transition metal elements are known. Using gradient corrected density functional theory we show that the 18-electron rule can be applied to design a new class of Zintl-like ions composed of all transition metal atoms. We demonstrate this possibility by using Ti@Au 12 2-and Ni@Au 6 2-di-anions as examples of Zintllike ions. Predictive capability of our approach is demonstrated by showing that FeH 6 4-in already synthesized complex metal hydride, Mg 2 FeH 6 , is a Zintl-like ion, satisfying the 18electron rule. Our results open door to the design and synthesis of a new class of Zintl-like ions with potential for applications.

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Quantum-classical correspondence of a field induced KAM-type transition: A QTM approach

Journal of Chemical Sciences, 2008

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A novel strategy for reversible hydrogen storage in Ca(BH4)2

Chemical Communications, 2015

We found that decomposition pathway of Ca(BH 4 ) 2 can be controlled by reaction temperature. Tha... more We found that decomposition pathway of Ca(BH 4 ) 2 can be controlled by reaction temperature. That is, it decomposes into CaB 6 at a lower temperature range of 320 to 350°C, but into amorphous boron at 400 to 450°C. We identified the formation of CaB 2 H 6 as the crucial intermediate step on the way to CaB 6 that only forms at 320 to 350°C.

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Electrophilicity Equalization Principle

Journal of Physical Chemistry Letters, Mar 8, 2010

A new electronic structure principle, viz., the principle of electrophilicity equalization is pro... more A new electronic structure principle, viz., the principle of electrophilicity equalization is proposed. An analytical justification as well as a numerical support for the same is provided. In this Letter, we propose a new electronic structure principle, viz., the principle of electrophilicity equalization and provide an analytical justification as well as a numerical support thereof. It states that, "During molecule formation, like electronegativity and hardness, electrophilicity gets equalized". Conceptual density functional theory 1-3 provides quantitative definitions for popular qualitative chemical concepts and theoretical bases for associated electronic structure principles. Chemical

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Stability, Reactivity, and Aromaticity of Compounds of a Multivalent Superatom

Journal of Physical Chemistry A, Oct 4, 2007

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A Bee-line Approach to Access Organocatalysts: A Suitable Base Catalyzed, Time-dependent, Chemoselective O-functionalization of Prolinol

Herein a successful chemoselective either functionalization of the nucleophilic sites of prolinol... more Herein a successful chemoselective either functionalization of the nucleophilic sites of prolinol by exploiting the relative acidity difference and inverted nucleophilicity of the corresponding conjugate bases, employing a suitable base is reported. An elaborate investigation into the overlooked sensitivity of reaction conditions to a highly utilized protocol has been reported. As an example, mono-Boc functionalization of prolinol for the exclusive synthesis of either NBoc/OBoc/Oxazolidinone derivatives is reported. Failing to emulate the former protocols, a mechanistic investigation was initiated which revealed that the rudimentary steps can be controlled by: a) a requisite base to recognize the differently acidic sites (NH and OH) for the formation of the conjugate base reacting to the electrophile, b) the disparity in nucleophilicity of the completely formed conjugate basic sites. This protocol has been extended to be successful with various other substrates, which might prove to...

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Ligand stabilization of manganocene dianions – in defiance of the 18-electron rule

Physical Chemistry Chemical Physics, 2019

Manganocene [Mn(C 5 H 5 ) 2 ], a 17-electron system, is expected to have a high electron affinity... more Manganocene [Mn(C 5 H 5 ) 2 ], a 17-electron system, is expected to have a high electron affinity, as addition of an extra electron would make it a closed-shell 18-electron system. Surprisingly, it has a very low electron affinity of only 0.28 eV. Combined with its high ionization potential of around 7.0 eV, manganocene, therefore, should not be eager to either donate or accept an electron. We show that this property can be fundamentally altered with the proper choice of ligands, even though the total electron count remains the same. For example, the electron affinities of manganocene-derivatives Mn[C 5 (CN) 5 ] 2 and Mn[C 5 (BO) 5 ] 2 , created by replacing H with CN or BO, are found to be 4.78 eV and 4.85 eV, respectively, making these species superhalogens. The power of the ligands is further demonstrated by studying the stability of their di-anions. Note that [Mn(C 5 X 5 ) 2 ] 2À (X = H, CN, BO) di-anions, with 19-electrons, have one electron more than necessary to satisfy the 18-electron rule for stability. This factor, combined with the unavoidable repulsion between the two extra electrons, should destabilize [Mn(C 5 X 5 ) 2 ] 2À . While that is the case for [Mn(C 5 H 5 ) 2 ] 2À , we show that both Mn[C 5 (CN) 5 ] 2 2À and Mn[C 5 (BO) 5 ] 2 2À are stable against auto-detachment of the second electron by 0.7 eV and 0.38 eV, respectively. These results, based on first-principles calculations, demonstrate that ligand-manipulation can be used as an effective strategy to design and synthesize new materials with novel and tailored properties. CN, BO), which possess 19-electrons, should not be stable and

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Exploring an intermolecular Ge/B frustrated Lewis pair from a multicentre Zintl Lewis base

Theoretical Chemistry Accounts

The possible existence of nonagermanide deltahedral Zintl ion (Ge94−) as a nine-folded Lewis base... more The possible existence of nonagermanide deltahedral Zintl ion (Ge94−) as a nine-folded Lewis base is investigated from first principles calculations. It is observed that all nine centres, Ge94−, can make an adduct with Lewis acid. The presence of lone pairs is confirmed from the 1c–2e AdNDP calculation. It is further noticed that the bulky group functionalized organo-Zintl cluster, [Ge9(tBu)3]− , can potentially act as a Lewis base and can make an intermolecular frustrated Lewis pair (FLP) with a well-known Lewis acid Tris[2,4,6-tris(trifluoromethyl)phenyl] borane, [B{C6H2(CF3)3}3].

Analyzing the Efficiency of Mn-(C2H4) (M = Sc, Ti, Fe, Ni; n = 1, 2) Complexes as Effective Hydrogen Storage Materials

arXiv (Cornell University), Sep 2, 2010

Hydrogen trapping ability of various metal-ethylene complexes has been studied at the B3LYP and M... more Hydrogen trapping ability of various metal-ethylene complexes has been studied at the B3LYP and MP2 level of theory using the 6-311+G(d,p) basis set. Different global and local reactivity descriptors and the associated electronic structure principles provide important insights into the associated interactions. There exist two distinct classes of bonding patterns, viz., a Kubas-type interaction between the metal and the H2 molecule behaving as a η2-ligand and an electrostatic interaction between the metal and the atomic hydrogens.

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Bonding, Aromaticity, and Possible Bond-Stretch Isomerism in an “All-Metal” Cluster—[Be6Zn2]2−

Aromaticity and Metal Clusters, 2010

Bonding, Aromaticity, and Possible Bond-Stretch Isomerism in an All-Metal Cluster[Be6Zn2] 2− S... more

Carbazole functionalized new bipolar ligand for monochromatic red light-emitting europium(iii) complex: combined experimental and theoretical study

New Journal of Chemistry, 2017

Complete energy transfer observed from carbazole functionalized bipolar ligand as well as β-diket... more

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A Conceptual DFT Approach Towards Developing New QSTR Models

Quantitative-structure-toxicity-relationship (QSTR) models are developed for predicting the toxic... more Quantitative-structure-toxicity-relationship (QSTR) models are developed for predicting the toxicity (pIGC 50) of 252 aliphatic compounds on Tetrahymena pyriformis. The single parameter models with a simple molecular descriptor, the number of atoms in the molecule, provide unbelievable results. Better QSTR models with two parameters result when global electrophilicity is used as the second descriptor. In order to tackle both charge-and frontier-controlled reactions the importance of the local electro (nucleo) philicities and atomic charges is also analyzed. Best possible three parameter QSTR models are prescribed.

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Exchange bias effect at the irregular interfaces between Co and CoO nanostructures

Journal of Alloys and Compounds, 2009

Nanostructures of Co and CoO particles were synthesized by using a modified sol–gel technique. Co... more Nanostructures of Co and CoO particles were synthesized by using a modified sol–gel technique. Coexistence of Co and CoO with fcc structure is identified by powder X-ray diffraction and electron diffraction studies. Particle sizes are found to be in between 4nm and 13nm obtained from Transmission Electron Microscopy where high resolution images do not reveal any regular core-shell structure; rather it shows a coexistence of Co and CoO nanostructure having irregular interfaces between them. A considerable shift in the magnetic hysteresis loop associated with the substantial enhancement of coercivity (from ∼1.0kOe to ∼3.7kOe) is observed at 5K when the composite was cooled in field-cooled mode with a static cooling field, Hcool=8kOe. The shift in the hysteresis loop is the typical manifestation of exchange bias effect which is strongly dependent on the cooling field. The results reveal that substantial enhancement of coercivity is attributed to the strong exchange coupling at the irregular Co/CoO interfaces where strong exchange bias effect does not require any regular core-shell structure.

In silico designing of Si- and Ge-doped imidazolium: a new heterocyclic aromatic superacid

Theoretical Chemistry Accounts

A Conceptual DFT Approach Toward Analyzing Hydrogen Storage Potential

Conceptual Density Functional Theory

Unraveling H2O activation by intermolecular frustrated Lewis pair

Chemical Physics Letters

Synthesis, structure, electrochemistry, fluorescent and DFT study of RuII complexes with pincer-type 2,6-bis-(N-methylimidazolylidene/ benzimidazolylidene)pyrazine ligands

School of Applied Science, Applied Synthetic Chemical Research Lab., Haldia Institute of Technolo... more School of Applied Science, Applied Synthetic Chemical Research Lab., Haldia Institute of Technology, Haldia-721 657, Purba Medinipur, West Bengal, India Department of Chemistry, Jadavpur University, Jadavpur, Kolkata-700 032, India Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology Kharagpur, Kharagpur-721 302, West Bengal, India Department of Chemistry, National Dong Hwa University, Hualion, Taiwan, ROC Department of Basic Science, Global Institute of Science and Technology, ICARE Complex, Haldia-721 657, Purba Medinipur, West Bengal, India Current address : Department of Chemistry, ITM University, Turari Campus, Gwalior-474 001, Madhya Pradesh, India E-mail : joydevdinda@gmail.com Manuscript received online 13 February 2014, revised 10 August 2014, accepted 12 August 2014 Pyrazine based CNC-pincer proligands 2,6-di-(N-methylimidazolium)pyrazine dichloride, 1; 2,6-di-(N-methylbenzimidazolium)pyrazine dichloride, 2 and their RuII&lt...

A comparative analysis of Ru(II) complexes containing non-annulated and annulated N-heterocyclic carbene ligand towards structure, spectra, electrochemistry and biological activity

CERN European Organization for Nuclear Research - Zenodo, Dec 1, 2020

Increasing population, depleting ground water and uncertain precipitation is causing subsequent s... more Increasing population, depleting ground water and uncertain precipitation is causing subsequent shortage of potable water and making it inevitable to put an end to unrestricted use of potable water for all purposes. Therefore, the focus of the researches must be shifted toward the recovery and reuse of wastewater. Membrane bioreactor (MBR) has high possibility to give a way out from the aforesaid situation. MBR gives a very good quality effluent that can be used in all purposes other than drinking. A number of full-scale plants are there all over the globe for treating industrial as well as municipal wastewater. However, mass adoption of MBR treatment is not implemented because fouling of membrane and consumption of energy still remain serious challenges of the MBR technology. Here, the MBR process has been discussed from its preliminary stage to the recent developments, which render the effluent suitable for reuse. Also data of treatment efficiency for various wastewater streams have been provided for domestic and industrial wastewater as well as landfill leachate.

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