Debanjan Dhar

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Crystal (programming language)

10.5517/cc14c40n

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CCDC 2040906: Experimental Crystal Structure Determination

The Cambridge Structural Database (2021)

Daniel A. Kurtz Debanjan Dhar Noémie Elgrishi Banu Kandemir Sean F. McWilliams

10.5517/ccdc.csd.cc26hqp4

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CCDC 1845453: Experimental Crystal Structure Determination

The Cambridge Structural Database (2018)

Debanjan Dhar Gereon M. Yee William B. Tolman

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/ccdc.csd.cc1zybr0

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Perturbing the Copper(III)–Hydroxide Unit through Ligand Structural Variation

Journal of the American Chemical Society (2015)

Debanjan Dhar Gereon M. Yee Andrew D. Spaeth David W. Boyce Hongtu Zhang

Two new ligand sets, (pipMe)LH2 and (NO2)LH2 ((pipMe)L = N,N'-bis(2,6-diisopropylphenyl)-1-methylpiperidine-2,6-dicarboxamide, (NO2)L = N,N'-bis(2,6-diisopropyl-4-nitrophenyl)pyridine-2,6-dicarboxamide), are reported which are designed to perturb the overall electronics of the copper(III)-hydroxide core and the resulting effects on the thermodynamics and kinetics of its hydrogen-atom abstraction (HAT) reactions. Bond dissociation energies (BDEs) for the O-H bonds of the corresponding Cu(II)-OH2 complexes were measured that reveal that changes in the redox potential for the Cu(III)/Cu(II) couple are only partially offset by opposite changes in the pKa, leading to modest differences in BDE among the three compounds. The effects of these changes were further probed by evaluating the rates of HAT by the corresponding Cu(III)-hydroxide complexes from substrates with C-H bonds of variable strength. These studies revealed an overarching linear trend in the relationship between the log k (where k is the second-order rate constant) and the ΔH of reaction. Additional subtleties in measured rates arise, however, that are associated with variations in hydrogen-atom abstraction barrier heights and tunneling efficiencies over the temperature range from -80 to -20 °C, as inferred from measured kinetic isotope effects and corresponding electronic-structure-based transition-state theory calculations.

Variation (astronomy)

10.1021/jacs.5b10985

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Mechanistic Dichotomy in Proton-Coupled Electron-Transfer Reactions of Phenols with a Copper Superoxide Complex

Journal of the American Chemical Society (2019)

Wilson D. Bailey Debanjan Dhar Anna C. Cramblitt William B. Tolman

The kinetics and mechanism(s) of the reactions of [K(Krypt)][LCuO2] (Krypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, L = a bis(arylcarboxamido)pyridine ligand) with 2,2,6,6-tetramethylpiperdine- N-hydroxide (TEMPOH) and the para-substituted phenols XArOH (X = para substituent NO2, CF3, Cl, H, Me, tBu, OMe, or NMe2) at low temperatures were studied. The reaction with TEMPOH occurs rapidly ( k = 35.4 ± 0.3 M-1 s-1) by second-order kinetics to yield TEMPO• and [LCuOOH]- on the basis of electron paramagnetic resonance spectroscopy, the production of H2O2 upon treatment with protic acid, and independent preparation from reaction of [NBu4][LCuOH] with H2O2 ( Keq = 0.022 ± 0.007 for the reverse reaction). The reactions with XArOH also follow second-order kinetics, and analysis of the variation of the k values as a function of phenol properties (Hammett σ parameter, O-H bond dissociation free energy, p Ka, E1/2) revealed a change in mechanism across the series, from proton transfer/electron transfer for X = NO2, CF3, Cl to concerted-proton/electron transfer (or hydrogen-atom transfer) for X = OMe, NMe2 (data for X = H, Me, tBu are intermediate between the extremes). Thermodynamic analysis and comparisons to previous results for LCuOH, a different copper-oxygen intermediate with the same supporting ligand, and literature for other [CuO2]+ complexes reveal significant differences in proton-coupled electron-transfer mechanisms that have implications for understanding oxidation catalysis by copper-containing enzymes and abiological catalysts.

Proton-Coupled Electron Transfer

10.1021/jacs.9b00466

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銅(III)‐水酸化物ユニットとフェノール類の反応性【Powered by NICT】

Chemical Science (Web) (2017)

Debanjan Dhar M Yee Gereon F Markle Todd M Mayer James B Tolman William

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CCDC 1424159: Experimental Crystal Structure Determination

The Cambridge Structural Database (2016)

Akram Ali Debanjan Dhar Suman K. Barman Francesc Lloret Rabindranath Mukherjee

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/ccdc.csd.cc1jsymw

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CCDC 1845455: Experimental Crystal Structure Determination

The Cambridge Structural Database (2018)

Debanjan Dhar Gereon M. Yee William B. Tolman

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/ccdc.csd.cc1zybt2

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CCDC 1448969: Experimental Crystal Structure Determination

The Cambridge Structural Database (2016)

Debanjan Dhar Gereon M. Yee Andrew D. Spaeth David W. Boyce Hongtu Zhang

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/cc1kmryw

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CCDC 1448973: Experimental Crystal Structure Determination

The Cambridge Structural Database (2016)

Debanjan Dhar Gereon M. Yee Andrew D. Spaeth David W. Boyce Hongtu Zhang

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Crystal (programming language)

10.5517/cc1kms21

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