Charge Transfer Assisted by Collective Hydrogen‐Bonding Dynamics

Mohammed, Omar F.; Kwon, Oh‐Hoon; Othon, Christina M.; Zewail, Ahmed H.

doi:10.1002/anie.200902340

Cited by 58 publications

(58 citation statements)

References 45 publications

(49 reference statements)

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“…[8][9][10] Many fundamental photophysical and photochemical properties of organic molecules including charge transfer, charge separation and charge recombination are well understood in several chemical systems using time-resolved laser spectroscopy. 1,[11][12][13][14] On the other hand, most of those organic molecules exhibit very low photoluminescence quantum yields (PLQY) especially in liquid phase, depending on the active non-radiative deactivation channels present such as torsional/twisting motions, excited state structural changes and ultrafast internal conversion. [15][16][17][18][19] For instance, torsional motions are commonly known as a very efficient non-radiative deactivation mechanisms for organic molecules upon photon-excitation in a wide range of fields including biological and chemical systems as well as solid-state photovoltaic materials.…”

Section: Introductionmentioning

confidence: 99%

Tunable Twisting Motion of Organic Linkers via Concentration and Hydrogen-Bond Formation

et al. 2019

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Benzothidiazole dibenzoic acid derivative (BTDB) is a well-known organic linker in various metal-organic framework structures as well as a fluorescent probe in biological systems. Here, we demonstrate that the radiative and non-radiative decay channels of BTDB can be interplayed and precisely controlled through concentration and hydrogen bond interactions as directly evidenced experimentally and theoretically. This leads to excited-state structural changes that significantly suppress the torsional motion around the Benzothidiazole moiety, leading to an enormous increase in the emission quantum yields from ~1% to 70%. These changes are associated with the existence of two equilibria where dimers and small-oligomers form in dimethylformamide (DMF), with high formation constants of 18,000 M-1 and 1.2 × 10 13 M-3 , respectively. These evolving species, i.e., the dimers and oligomers, are formed via hydrogen bonds between carboxylic acid groups present at the far-edge of the rod-like BTDB molecules. The estimated repeating number for this smalloligomer formation via bonded monomers is eight in DMF, as shown by emission spectra analysis. With deprotonation as a control experiment, these associated species can easily collapse to the initial monomer species, confirming the role of the hydrogen-bond formation on the observed phenomena. Theoretical studies and NMR experiments not only confirm the existence of the dimers, but also demonstrate the important role of the hydrogen bonds on the excited-state dynamics. These new findings provide a better understanding of the photophysical behaviors of organic linkers used in a wide range of chemical and biological applications.

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Section: Introductionmentioning

confidence: 99%

Tunable Twisting Motion of Organic Linkers via Concentration and Hydrogen-Bond Formation

et al. 2019

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“…The electron transfer (ET) is one of the most fundamental chemical processes and has been studied intensively in the fields of physical chemistry and biology [1][2][3][4]. Since the discovery of ferrocene (Fc), it has played an important role in the ET processes in organometallic systems.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Mohammed

Sarhan

2010

Chemical Physics

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“…Based on the chemical structure of CNS discussed above, the nature of the solute–solvent interaction (i.e., solvation) can be discussed at a molecular level. Solvation comprises nonspecific and specific interactions, which result from the dipolarity/polarizability and H‐bonding capability of a solvent, respectively . While the E T (30) index of solvents is commonly used to represent the polarity of solvents, the value is obtained from the phenomenological solvatochromism of a dye in a series of solvents .…”

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confidence: 99%

Morphology Tunable Hybrid Carbon Nanosheets with Solvatochromism

et al. 2017

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The tunable photoluminescence of carbon-based nanomaterials has received much attention for a wide range of applications. Herein, a unique, broad-solvatochromic hybrid carbon nanosheet (CNS) synthesized through the hydrothermal carbonization of molecular precursors exploiting graphene oxide as a template is reported, resulting in the formation of clusters of carbon nanorings on the surface of graphene-oxide nanosheets. Under UV and visible-light excitation, the hybrid CNS exhibits tunable emission spanning the wide range of colors in a series of solvents with different polarities. This interesting spectroscopic behavior is found to originate from hydrogen-bonding interactions between CNS and solvents, which eventually induce the morphological transition of CNS from 2D sheets to 3D crumpled morphologies, affecting the lifetimes of emissive states. This novel soft carbon nanostructure may open up a new possibility in tailoring the photophysical properties of carbon nanomaterials.

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Charge Transfer Assisted by Collective Hydrogen‐Bonding Dynamics

Cited by 58 publications

References 45 publications

Tunable Twisting Motion of Organic Linkers via Concentration and Hydrogen-Bond Formation

Tunable Twisting Motion of Organic Linkers via Concentration and Hydrogen-Bond Formation

Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Morphology Tunable Hybrid Carbon Nanosheets with Solvatochromism

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