@article { ISI:000375631300006, title = {Correlating Nitrile IR frequencies to local electrostatics quantifies noncovalent interactions of peptides and proteins}, journal = {Journal of Physical Chemistry B}, volume = {120}, number = {17}, year = {2016}, month = {MAY}, pages = {4034-4046}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Noncovalent interactions, in particular the hydrogen bonds and nonspecific long-range electrostatic interactions are fundamental to biomolecular functions. A molecular understanding of the local electrostatic environment, consistently for both specific (hydrogen-bonding) and nonspecific electrostatic (local polarity) interactions, is essential for a detailed understanding of these processes. Vibrational Stark Effect (VSE) has proven to be an extremely useful method to measure the local electric field using infrared spectroscopy of carbonyl and nitrile based probes. The nitrile chemical group would be an ideal choice because of its absorption in an infrared spectral window transparent to biomolecules, ease of site-specific incorporation into proteins, and common occurrence as a substituent in various drug molecules. However, the inability of VSE to describe the dependence of IR frequency on electric field for hydrogen-bonded nitriles to date has severely limited nitrile{\textquoteright}s utility to probe the noncovalent interactions. In this work, using infrared spectroscopy and atomistic molecular dynamics simulations, we have reported for the first time a linear correlation between nitrile frequencies and electric fields in a wide range of hydrogen-bonding environments that may bridge the existing gap between VSE and H-bonding interactions. We have demonstrated the robustness of this field-frequency correlation for both aromatic nitriles and sulfur-based nitriles in a wide range of molecules of varying size and compactness, including small molecules in complex solvation environments, an amino acid, disordered peptides, and structured proteins. This correlation, when coupled to VSE, can be used to quantify noncovalent interactions, specific or nonspecific, in a consistent manner.

}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.6b02732}, author = {Deb, Pranab and Haldar, Tapas and Kashid, Somnath M. and Banerjee, Subhrashis and Chakrabarty, Suman and Bagchi, Sayan} } @article {43030, title = {Decoding the morphological diversity in two dimensional crystalline porous polymers by core planarity modulation}, journal = {Angewandte Chemie - International Edition}, volume = {55}, year = {2016}, month = {JUN}, pages = {7806-7810}, doi = {10.1002/anie.201600087}, author = {Halder, Arjun and Kandambeth, Sharath and Biswal, Bishnu P. and Kaur, Gagandeep and Roy, Neha Chaki and Addicoat, Matthew A. and Salunke, Jagadish K. and Banerjee, Subhrashis and Vanka, Kumar and Heine, Thomas and Verma, Sandeep and Banerjee, Rahul} } @article {42825, title = {[3+2]-Annulation of platinum-bound azomethine ylides with distal C[double bond, length as m-dash]C bonds of N-allenamides}, journal = {Chemical Communications}, volume = {53}, year = {2017}, month = {JAN}, pages = {196-199}, type = {Article}, abstract = {

A Pt-catalyzed, highly regioselective reaction between N-allenamides and imino-alkynes leading to pyrrolo[1,2-a] indoles is described. This represents the first example of [3+2]-annulation of Pt-bound azomethine ylides with the distal CQC bond of N-allenamides. The mechanism of the reaction was established by computational studies.

}, doi = {10.1039/c6cc07874e}, author = {Chakrabarty, Indradweep and Inamdar, Suleman M. and Akram, Manjur O. and Gade, Amol B. and Banerjee, Subhrashis and Bera, Saibal and Patil, Nitin T.} } @article {43741, title = {Interplaying anions in a supramolecular metallohydrogel to form metal organic frameworks}, journal = {Chemical Communications}, volume = {53}, year = {2017}, month = {APR}, pages = {3705-3708}, type = {Article}, abstract = {The remarkable effect of anions on the transition from supramolecular gels to crystalline phases has been described. An amino acid-based metallohydrogel was transformed into different metal-organic frameworks through the selective picking of anions. The metallohydrogel and the resulting metal-organic frameworks (MOFs) were thoroughly characterized. The results demonstrated controlled access over the binding of a particular anion to selectively form a particular MOF.}, doi = {10.1039/c7cc00539c}, author = {Karak, Suvendu and Kumar, Sushil and Bera, Saibal and Diaz Diaz, David and Banerjee, Subhrashis and Vanka, Kumar and Banerjee, Rahul} } @article {43721, title = {Porous porphyrin organic polymer (PPOP) for visible light triggered hydrogen production}, journal = {Chemical Communications}, volume = {53}, year = {2017}, month = {APR}, pages = {4461-4464}, type = {Article}, chapter = {4461-4464}, abstract = {A visible light active porphyrin-based porous organic polymer having high chemical stability and surface area has been synthesized and its ability to influence the photocatalytic activity of large band gap-TiO2 nanoparticles has been tested. The resultant composite shows improved photocatalytic activity as compared to the parent precursors. This study provides insights into the photosensitizing ability of the polymer in addition to its ability to firmly harbor nanoparticles onto its surface.}, doi = {10.1039/c7cc00879a}, author = {Mukherjee, Gargi and Thote, Jayshri and Aiyappa, Harshitha Barike and Kandambeth, Sharath and Banerjee, Subhrashis and Vanka, Kumar and Banerjee, Rahul} } @article { ISI:000371453700057, title = {Self-exfoliated guanidinium-based ionic covalent organic nanosheets (iCONs)}, journal = {Journal of the American Chemical Society}, volume = {138}, number = {8}, year = {2017}, month = {MAR}, pages = {2823-2828}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Covalent organic nanosheets (CONs) have emerged as functional two-dimensional materials for versatile applications. Although pi-pi stacking between layers, hydrolytic instability, possible restacking prevents their exfoliation on to few thin layered CONs from crystalline porous polymers. We anticipated rational designing of a structure by intrinsic ionic linker could be the solution to produce self-exfoliated CONs without external stimuli. In an attempt to address this issue, we have synthesized three self-exfoliated guanidinium halide based ionic covalent organic nanosheets (iCONs) with antimicrobial property. Self-exfoliation phenomenon has been supported by molecular dynamics (MD) simulation as well. Intrinsic ionic guanidinium unit plays the pivotal role for both self-exfoliation and antibacterial property against both Gram-positive and Gram-negative bacteria. Using such iCONs, we have devised a Mixed matrix membrane which could be useful for antimicrobial coatings with plausible medical benefits.

}, issn = {0002-7863}, doi = {10.1021/jacs.5b13533}, author = {Mitra, Shouvik and Kandambeth, Sharath and Biswal, Bishnu P. and Khayum, Abdul M. and Choudhury, Chandan Kumar and Mehta, Mihir R. and Kaur, Gagandeep and Banerjee, Subhrashis and Prabhune, Asmita and Verma, Sandeep and Roy, Sudip and Kharul, Ulhas K. and Banerjee, Rahul} } @article {44624, title = {B(C6F5)(3): catalyst or initiator? insights from computational studies into surrogate silicon chemistry}, journal = {ACS Catalysis}, volume = {8}, year = {2018}, month = {JUL}, pages = {6163-6176}, type = {Article}, abstract = {

One of the most promising recent developments in catalysis has been the use of the metal-free Lewis acid B(C6F5)(3) as a catalyst for a range of different chemical transformations. Perhaps the most impressive achievement in this regard is the recently accomplished in situ generation of SiH4 from surrogates (Simonneau and Oestreich, Nat. Chem., 2015,7, 816). However, what the current computational work, with density functional theory, reveals is that this process, in addition to being catalyzed by B(C6F5)(3), is also significantly dominated by a series of autocatalytic reactions. The results are further corroborated by the use of the energetic span model, which shows that the turnover frequency is higher for the newly proposed autocatalytic pathway in comparison to the conventional B(C6F5)(3)-catalyzed pathway. The current work therefore provides interesting new insights into surrogate silicon chemistry. But, more importantly, the current studies indicate that B(C6F5)(3) is likely to function more as an initiator rather than a pure catalyst in many metal-free transformations that have been reported to date.

}, keywords = {autocatalysis, Density functional theory, ion-pair, Lewis acid catalysis, reaction mechanism, surrogate silicone chemistry, tris(pentafluorophenyl)borane}, issn = {2155-5435}, doi = {10.1021/acscatal.7b04489}, author = {Banerjee, Subhrashis and Vanka, Kumar} } @article {44374, title = {Catalytic enantioselective 1,3-alkyl shift in alkyl aryl ethers: efficient synthesis of optically active 3,3 {\textquoteright}-diaryloxindoles}, journal = {Angewandte Chemie-International Edition}, volume = {57}, year = {2018}, month = {MAY}, pages = {5735-5739}, abstract = {Reported is the first organocatalytic asymmetric 1,3-alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3{\textquoteright}-diaryloxindoles using a chiral Bronsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3{\textquoteright}-diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.}, doi = {10.1002/anie.201801650}, author = {Gade, Amol B. and Bagle, Pradip N. and Shinde, Popat S. and Bhardwaj, Vipin and Banerjee, Subhrashis and Chande, Ajit and Patil, Nitin T.} } @article {44352, title = {Understanding interactions between lignin and ionic liquids with experimental and theoretical studies during catalytic depolymerisation}, journal = {Catalysis Today}, volume = {309}, year = {2018}, month = {JUL}, pages = {98-108}, type = {Article}, abstract = {Compared to H2SO4, Bronsted acidic ionic liquid (BAIL, [C3SO3HMIM][HSO4]) catalyzed depolymerization of lignin yielded higher concentration of low molecular weight products under mild conditions (120 degrees C) as proven by GC and GC-MS. To comprehend this disparity in catalytic activity among H2SO4 and BAIL (at similar H+ concentration), experimental techniques [1D(H-1) NMR, 2D(N-15/H-1 HMBC) NMR and RAMAN] have been employed. Based on these studies, it has been proven that the transfer of electron density from substrate to the electron deficient imidazolium ring via formation of hydrogen bond between -OH/OCH3 (substrate) and -N1C2H2N3-(cation) is possible, while the anion plays an important role. Further, density functional theory (DFT) calculations also corroborated this fact by showing a change in the bond angle and decrease in bond length (C-2-H-2 in imidazole), due to the presence of weak and strong hydrogen bonding between the substrate and IL.}, doi = {10.1016/j.cattod.2017.09.050}, author = {Singh, Sandip Kumar and Banerjee, Subhrashis and Vanka, Kumar and Dhepe, Paresh Laxmikant} } @article {48383, title = {Computational insights into hydroboration with acyclic alpha-Borylamido-germylene and stannylene catalysts: Cooperative dual catalysis the key to system efficiency}, journal = {Polyhedron}, volume = {222}, year = {2022}, month = {AUG}, pages = {115907}, type = {Article}, abstract = {

The chemistry of low valent main group compounds has grown as an alternative to the chemistry of less abundant and less green transition metal complexes. It has been found that low valent compounds such as carbenes, silylenes, stannylenes and germylenes are efficient for activating small molecules and for catalysis. However, the reaction mechanism and the factors that affect the rate of reaction are not completely understood. In this computational investigation with density functional theory (DFT), we investigate and demonstrate the efficiency of a new mechanism for the hydroboration of aldehydes by germylenes and stannylenes, in the presence of the common hydroborating agent, pinacolborane, HBpin. This mechanism involves an HBpin molecule as an additional catalyst that cooperates with the germylene or stannylene catalyst to efficiently carry out the hydroboration. This mechanism is first demonstrated to work for experimentally reported systems, and then shown to be efficient for newly proposed germylene and stannylene systems. These new systems are alpha-Borylamido-germylene ((2,6-iPr(2)C(6)H(3)NBCy(2))(2)Ge(II)) and alpha-Borylamido-stannylene((2,6-iPr(2)C(6)H(3)NBCy(2))(2)Sn(II)). These new insights will help researchers look into low valent germylene and stannylene chemistry from a new perspective.

}, keywords = {Catalysis of hydroboration, computational chemistry, Germylenes and stannylenes, Main group chemistry, New mechanism}, issn = {0277-5387}, doi = {10.1016/j.poly.2022.115907}, author = {Banerjee, Subhrashis and Vanka, Kumar} } @article {48263, title = {Controlled reduction of isocyanates to formamides using monomeric magnesium}, journal = {Chemical Communications}, volume = {59}, year = {2023}, month = {FEB}, pages = {2255-2258}, type = {Article}, abstract = {

This work describes a transition metal-free methodology involving an efficient and controlled reduction of isocyanates to only formamide derivatives using pinacolborane (HBpin) as the hydrogenating agent and a bis(phosphino)carbazole ligand stabilized magnesium methyl complex (1) as the catalyst. A large number of substrates undergo selective hydroboration and give exclusively N-boryl formamides.

}, issn = {1359-7345}, doi = {10.1039/d3cc00036b}, author = {Kumar, Rohit and Sharma, Vishal and Banerjee, Subhrashis and Vanka, Kumar and Sen, Sakya S.} } @article {48714, title = {"Weak" C-H{\textbullet}{\textbullet}{\textbullet}S interaction drives enantioselectivity in cinchona alkaloid complex catalyzed thiocyanation}, journal = {Chemistry-An Asian Journal}, volume = {18}, year = {2023}, month = {JUL}, pages = {e202300321}, type = {Article}, abstract = {

The great success of asymmetric organocatalysis has made it one of the most important advancements made in chemistry in the past two decades. A significant achievement in this context is the asymmetric organocatalysis of the thiocyanation reaction. In the current study, computational studies with density functional theory have been done in order to understand an interesting experimental finding: the reversal of enantioselectivity from R to S when the electrophile is changed from beta-keto ester to oxindole for the thiocyanation reaction with the cinchona alkaloid complex catalyst. The calculations reveal an unusual fact - the principal reason for the reversal is the presence of the C-H center dot center dot center dot S noncovalent interaction, which is present only in the major transition states in each of the two nucleophile cases. Only recently has it been realized that the supposedly weak C-H center dot center dot center dot S noncovalent interaction has the properties of a hydrogen bond, and the fact that this interaction is the cause of enantioselectivity has relevance, because of the large number of asymmetric transformations involving the sulphur heteroatom.

}, keywords = {Density functional calculations, Enantioselectivity, noncovalent interactions, organocatalysis, reaction mechanisms}, issn = {1861-4728}, doi = {10.1002/asia.202300321}, author = {Banerjee, Subhrashis and Vanka, Kumar} }