ORCID Profile
0000-0001-9824-0720
Current Organisation
University of Leeds
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Publisher: American Chemical Society (ACS)
Date: 23-02-2015
DOI: 10.1021/JA512020W
Abstract: In aprotic solvents, Lewis basic F(-) anion reduces Lewis acidic Ag(I) cation to Ag(0), forming metallic silver mirrors on the inner surfaces of reaction vessels and luminescent Ag-nanoparticles (AgNPs) in supernatant solutions, which emit blue light upon UV irradiation. The F(-)-induced formation of silver mirrors and AgNPs was confirmed through X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), fluorescence spectroscopy, and mass spectrometry, whereas the Ag(I)-induced oxidation of F(-) to Ḟ radical, followed by its conversion to HF2(-) via H-abstraction and H-bonding, was evident from (19)F NMR spectroscopy. This redox reaction is deactivated in water, as the reducing power of hydrated F(-) diminishes drastically. Less Lewis basic Cl(-), Br(-), and I(-) ions do not reduce Ag(I) to Ag(0), instead they can only form Ag(I) halide precipitates irrespective of protic or aprotic solvents. The Ag-coated surfaces, luminescent AgNPs, and Ḟ radicals produced by this unprecedented redox reaction could be exploited as electrodes, light-emitting materials, and radical initiators, respectively.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3OB40703A
Abstract: Over the past decade anion-π interaction has emerged as a new paradigm of supramolecular chemistry of anions. Taking advantage of the electronic nature of anion-π interaction, we have expanded its boundaries to charge-transfer (CT) and formal electron transfer (ET) events by adjusting the electron-donating and accepting abilities of anions and π-acids, respectively. To establish that ET, CT, and anion-π interactions could take place between different anions and π-acids as long as their electronic and structural properties are conducive, herein, we introduce 3,4,9,10-perylenediimide (PDI-1) that selectively undergoes thermal ET from strong Lewis basic hydroxide and fluoride anions, but remains electronically and optically silent to poor Lewis basic anions, as ET and CT events are turned OFF. These interactions have been fully characterized by UV/Vis, NMR, and EPR spectroscopies. These results demonstrate the generality of anion-induced ET events in aprotic solvents and further refute a notion that strong Lewis basic hydroxide and fluoride ions can only trigger nucleophilic attack to form covalent bonds instead of acting as sacrificial electron donors to π-acids under appropriate conditions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CC47498D
Abstract: Dye-sensitized solar cells comprised of supramolecular light-harvesting zinc-phthalocyanine⋯peryleneimide dyads on TiO 2 films generate photoelectricity throughout the 300–650 nm region with the power conversion efficiency reaching up to 2.3% and the incident-photon-to-current-efficiency up to 40% under one-sun conditions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC33120A
Abstract: Multichromophoric dye-sensitized solar cells (DSCs) based on self-assembled zinc-porphyrin···peryleneimide dyads on TiO(2) films display more efficient light-to-electrical energy conversion than DSCs based on in idual dyes. Higher efficiency of multichromophoric dyes can be attributed to co-sensitization as well as vectorial electron transfer that lead to better electron-hole separation in the device.
Publisher: Elsevier BV
Date: 03-2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5TC02232K
Abstract: The formation of guest-mediated π-donor/acceptor stacks within electroactive metal–organic frameworks activates long-range charge mobilization, boosting the electrical conductivity of the doped materials.
Publisher: American Chemical Society (ACS)
Date: 15-09-2017
Abstract: A new honeycomb-shaped electroactive metal-organic framework (MOF) has been constructed from an electron deficient naphthalenediimide (NDI) ligand equipped with two terminal salicylic acid groups. π-Intercalation of electron-rich planar tetrathiafulvalene (TTF) guests between the NDI ligands stacked along the walls lowers the electronic band gap of the material by ca. 1 eV. An improved electron delocalization through the guest-mediated π-donor/acceptor stacks is attributed to the diminished band gap of the doped material, which forecasts an improved electrical conductivity.
Publisher: American Chemical Society (ACS)
Date: 06-02-2018
DOI: 10.1021/ACS.ORGLETT.7B03861
Abstract: A novel heteroditopic ion-pair receptor was synthesized by tethering two π-acidic naphthalenediimide units with a tridentate bisimine linker. Upon chelating a Zn
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC43178A
Abstract: A non-interpenetrated square grid metal-organic framework (MOF) comprised of octahedral Zn(II) ions and linear N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNDI) ligands was formed in the presence of noncoordinating perchlorate counterions that occupied the cavities of the porous network by forming CH···anion hydrogen bonds with DPNDI ligands, whereas a linear coordination polymer was obtained when Zn(II)-coordinated nitrate ions were present as counterions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC40535D
Abstract: Depending on functional groups, hiphilic hexaamide macrocycles self-assemble into closed-shell and open-shell vesicles in polar solvents. In the presence of water, open-shell vesicles morph into closed-shell vesicles, whereas acidification of the medium transforms vesicles into nanotubes and fibers.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Sikha Saha.