scholarly journals Ultrafast photoactivation of C─H bonds inside water-soluble nanocages

2019 ◽  
Vol 5 (2) ◽  
pp. eaav4806 ◽  
Author(s):  
Ankita Das ◽  
Imon Mandal ◽  
Ravindra Venkatramani ◽  
Jyotishman Dasgupta
Keyword(s):  
Charge Transfer ◽  
Degrees Of Freedom ◽  
Bond Cleavage ◽  
Electron Transfer Reaction ◽  
Water Soluble ◽  
Charge Transfer Complexes ◽  
Chemical Bonds ◽  
Proton Coupled Electron Transfer ◽  
Selective Reaction ◽  
Carbon Centered Radical

Light energy absorbed by molecules can be harnessed to activate chemical bonds with extraordinary speed. However, excitation energy redistribution within various molecular degrees of freedom prohibits bond-selective chemistry. Inspired by enzymes, we devised a new photocatalytic scheme that preorganizes and polarizes target chemical bonds inside water-soluble cationic nanocavities to engineer selective functionalization. Specifically, we present a route to photoactivate weakly polarized sp3C─H bonds in water via host-guest charge transfer and control its reactivity with aerial O2. Electron-rich aromatic hydrocarbons self-organize inside redox complementary supramolecular cavities to form photoactivatable host-guest charge transfer complexes in water. An ultrafast C─H bond cleavage within ~10 to 400 ps is triggered by visible-light excitation, through a cage-assisted and solvent water–assisted proton-coupled electron transfer reaction. The confinement prolongs the lifetime of the carbon-centered radical to enable a facile yet selective reaction with molecular O2leading to photocatalytic turnover of oxidized products in water.

scholarly journals Water-Soluble Visible Light Sensitive Photoinitiating System Based on Charge Transfer Complexes for the 3D Printing of Hydrogels

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3195
Author(s):  
Hong Chen ◽  
Mehdi Vahdati ◽  
Pu Xiao ◽  
Frédéric Dumur ◽  
Jacques Lalevée
Keyword(s):  
Charge Transfer ◽  
3D Printing ◽  
Visible Light ◽  
Water Solubility ◽  
Charge Transfer Complex ◽  
Water Soluble ◽  
Charge Transfer Complexes ◽  
Free Radical Photopolymerization ◽  
Potential Applications ◽  
A Charge

The development of visible-light 3D printing technology by using water-soluble initiating systems has attracted widespread attention due to their potential applications in the manufacture of hydrogels. Besides, at present, the preparation of water-soluble photoinitiators suitable for visible light irradiation (such as LEDs) still remains a challenge. Therefore, this work is devoted to developing water-soluble photoinitiators (PI)/photoinitiating systems (PIS) upon irradiation with a LED @ 405 nm. In detail, a new water-slightly-soluble chalcone derivative dye [(E)-3-(4-(dimethylamino) phenyl)-1-(4-(2-(2-(2-methoxyethoxy) ethoxy) ethoxy) phenyl) prop-2-en-1-one] was synthesized here and used as a PI with a water-soluble coinitiator, i.e., triethanolamine (TEA) which was also used as an electron donor. When combined together, a charge transfer complex (CTC) formed immediately which exhibited excellent initiating ability for the free radical photopolymerization of poly(ethyleneglycol)diacrylate (PEG-DA). In light of the powerful CTC effect, the [dye-TEA] CTC could not only exhibit enhanced water solubility and mechanical properties but could also be effectively applied for 3D printing. This CTC system is environmentally friendly and cost-saving which demonstrates a great potential to prepare hydrogels via photopolymerization.

scholarly journals Building a molecular-level picture of the ultrafast dynamics of the charge-transfer-to-solvent (CTTS) reaction of sodide (Na¯)

2004 ◽  
Vol 76 (10) ◽  
pp. 1809-1823 ◽  
Author(s):  
I. B. Martini ◽  
E. R. Barthel ◽  
B. J. Schwartz
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Degrees Of Freedom ◽  
Molecular Level ◽  
Electron Transfer Reaction ◽  
Ultrafast Dynamics ◽  
Pump Probe ◽  
Back Electron Transfer ◽  
Dynamics Simulations ◽  
Ether Solvents

Charge-transfer-to-solvent (CTTS) reactions represent the simplest possible electron-transfer reaction. One of the reasons that such reactions have become the subject of recent interest is that transfer of a CTTS electron from an atomic anion to the solvent involves only electronic degrees of freedom, so that all the dynamics involved in the reaction are those of the solvent. Thus, CTTS reactions provide an outstanding spectroscopic window on the dynamics of the solvent during electron transfer. In this paper, we will review our recent work studying the CTTS reaction of the sodium anion, (Na− or sodide) in a series of ether solvents. By comparing the results of ultrafast spectroscopic pump/probe experiments and mixed quantum/classical molecular dynamics simulations, we work to build a molecular-level picture of how solvent motions control the dynamics of CTTS, including the distance to which the electron is ejected and the rates of both the forward and back electron-transfer reactions.

Magnetic properties of new charge-transfer complexes based on manganese porphyrins

1997 ◽  
Vol 90 (3) ◽  
pp. 407-413
Author(s):  
MARC KELEMEN ◽  
CHRISTOPH WACHTER ◽  
HUBERT WINTER ◽  
ELMAR DORMANN ◽  
RUDOLF GOMPPER ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Charge Transfer ◽  
Charge Transfer Complexes ◽  
Manganese Porphyrins

Charge Transfer Complexation Boosts Molecular Conductance Through Fermi Level Pinning

2018 ◽  
Author(s):  
Kun Wang ◽  
Andrea Vezzoli ◽  
Iain Grace ◽  
Maeve McLaughlin ◽  
Richard Nichols ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Single Molecule ◽  
Quantum Interference ◽  
Transmission Function ◽  
Scanning Tunneling ◽  
Charge Transfer Complexes ◽  
Tunneling Microscopy ◽  
Quantum Interference Effect ◽  
Single Molecule Junctions ◽  
Charge Transfer Complexation

We have used scanning tunneling microscopy to create and study single molecule junctions with thioether-terminated oligothiophene molecules. We find that the conductance of these junctions increases upon formation of charge transfer complexes of the molecules with tetracyanoethene, and that the extent of the conductance increase is greater the longer is the oligothiophene, i.e. the lower is the conductance of the uncomplexed molecule in the junction. We use non-equilibrium Green's function transport calculations to explore the reasons for this theoretically, and find that new resonances appear in the transmission function, pinned close to the Fermi energy of the contacts, as a consequence of the charge transfer interaction. This is an example of a room temperature quantum interference effect, which in this case boosts junction conductance in contrast to earlier observations of QI that result in diminished conductance.<br>

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