02608nas a2200205 4500008004100000022001400041245012400055210006900179260007100248300001400319490000800333520180600341100001602147700001802163700002402181700002502205700002302230700001802253856013102271 2016 eng d a1520-610600aCorrelating Nitrile IR frequencies to local electrostatics quantifies noncovalent interactions of peptides and proteins0 aCorrelating Nitrile IR frequencies to local electrostatics quant a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY a4034-40460 v1203 a

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'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.

1 aDeb, Pranab1 aHaldar, Tapas1 aKashid, Somnath, M.1 aBanerjee, Subhrashis1 aChakrabarty, Suman1 aBagchi, Sayan uhttps://library.ncl.res.in/content/correlating-nitrile-ir-frequencies-local-electrostatics-quantifies-noncovalent-interactions01121nas a2200205 4500008004100000245013100041210006900172260000800241300001400249490000700263520037000270100001900640700002200659700002200681700002000703700002500723700001700748700002100765856012900786 2018 eng d00aCatalytic enantioselective 1,3-alkyl shift in alkyl aryl ethers: efficient synthesis of optically active 3,3 '-diaryloxindoles0 aCatalytic enantioselective 13alkyl shift in alkyl aryl ethers ef cMAY a5735-57390 v573 aReported is the first organocatalytic asymmetric 1,3-alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3'-diaryloxindoles using a chiral Bronsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3'-diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.1 aGade, Amol, B.1 aBagle, Pradip, N.1 aShinde, Popat, S.1 aBhardwaj, Vipin1 aBanerjee, Subhrashis1 aChande, Ajit1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/catalytic-enantioselective-13-alkyl-shift-alkyl-aryl-ethers-efficient-synthesis-optically02178nas a2200217 4500008004100000022001400041245016800055210006900223260000800292300001100300490000800311520134000319653003101659653002801690653003101718653002501749653001801774100002501792700001701817856012601834 2022 eng d a0277-538700aComputational insights into hydroboration with acyclic alpha-Borylamido-germylene and stannylene catalysts: Cooperative dual catalysis the key to system efficiency0 aComputational insights into hydroboration with acyclic alphaBory cAUG a1159070 v2223 a

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.

10aCatalysis of hydroboration10acomputational chemistry10aGermylenes and stannylenes10aMain group chemistry10aNew mechanism1 aBanerjee, Subhrashis1 aVanka, Kumar uhttps://library.ncl.res.in/content/computational-insights-hydroboration-acyclic-alpha-borylamido-germylene-and-stannylene01049nas a2200193 4500008004100000022001400041245008000055210006900135260000800204300001400212490000700226520041600233100001700649700001900666700002500685700001700710700001900727856010900746 2023 eng d a1359-734500aControlled reduction of isocyanates to formamides using monomeric magnesium0 aControlled reduction of isocyanates to formamides using monomeri cFEB a2255-22580 v593 a

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.

1 aKumar, Rohit1 aSharma, Vishal1 aBanerjee, Subhrashis1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/controlled-reduction-isocyanates-formamides-using-monomeric-magnesium