Direct evidence of solvent polarity governing the intramolecular charge and energy transfer: ultrafast relaxation dynamics of push–pull fluorene derivatives

2019 ◽  
Vol 21 (21) ◽  
pp. 11087-11102 ◽  
Author(s):  
Afeefah U. Neelambra ◽  
Chinju Govind ◽  
Tessy T. Devassia ◽  
Guruprasad M. Somashekharappa ◽  
Venugopal Karunakaran
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Emission Spectroscopy ◽  
Direct Evidence ◽  
Transient Absorption ◽  
Intramolecular Charge Transfer ◽  
Solvent Polarity ◽  
Relaxation Dynamics ◽  
Ultrafast Relaxation ◽  
Absorption And Emission Spectroscopy

The occurrence of intramolecular charge transfer along with energy transfer controlled by the polarity of solvent is revealed by femtosecond and nanosecond transient absorption and emission spectroscopy.

Distinguishing Förster resonance energy transfer and solvent-mediated charge-transfer relaxation dynamics in a zinc(ii) indicator: a femtosecond time-resolved transient absorption spectroscopic study

2014 ◽  
Vol 16 (11) ◽  
pp. 5088-5092 ◽  
Author(s):  
Kesavapillai Sreenath ◽  
Chongyue Yi ◽  
Kenneth L. Knappenberger ◽  
Lei Zhu
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Transient Absorption ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Solvent Polarity ◽  
Forster Resonance Energy Transfer ◽  
Förster Resonance Energy Transfer ◽  
Relaxation Dynamics ◽  
Förster Resonance

The rates of intramolecular Förster resonance energy transfer and solvent-mediated relaxation of charge-transfer excited state have oppsite solvent polarity dependencies.

Ultrafast relaxation dynamics of phosphine-protected, rod-shaped Au20 clusters: interplay between solvation and surface trapping

2014 ◽  
Vol 16 (34) ◽  
pp. 18288-18293 ◽  
Author(s):  
Meng Zhou ◽  
Saran Long ◽  
Xiankai Wan ◽  
Yang Li ◽  
Yingli Niu ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Relaxation Dynamics ◽  
Coherent Oscillation ◽  
Ultrafast Relaxation

Excited-state intramolecular charge transfer dynanmics and coherent oscillation of ligand-protected rod shaped Au20 clusters were modulated through the competition between solvation and surface trapping.

scholarly journals A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 234
Author(s):  
Cheng Chen ◽  
Sean A. Boulanger ◽  
Anatolii I. Sokolov ◽  
Mikhail S. Baranov ◽  
Chong Fang
Keyword(s):  
Charge Transfer ◽  
Transient Absorption ◽  
Fluorescent Protein ◽  
Intramolecular Charge Transfer ◽  
Multivariable Analysis ◽  
Solvent Polarity ◽  
Dimethylamino Group ◽  
Twisted Intramolecular Charge Transfer

We discovered a novel fluorophore by incorporating a dimethylamino group (–NMe2) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an environment-polarity sensor in vitro and in vivo. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy in combination with quantum calculations revealed the presence of a twisted intramolecular charge transfer (TICT) state, which is formed by rotation of the –NMe2 group in the electronic excited state. In contrast to the bright fluorescent state (FS), the TICT state is dark and effectively quenches fluorescence upon formation. We employed a newly developed multivariable analysis approach to the FS lifetime in various solvents and showed that the FS → TICT reaction barrier is mainly modulated by H-bonding capability instead of viscosity of the solvent, accounting for the observed polarity dependence. These deep mechanistic insights are further corroborated by the dramatic loss of fluorogenicity for two similar GFP-derived chromophores in which the rotation of the –NMe2 group is inhibited by structural locking.

scholarly journals Photoexcitation of Ge9− Clusters in THF: New Insights into the Ultrafast Relaxation Dynamics and the Influence of the Cation

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2639
Author(s):  
Nadine C. Michenfelder ◽  
Christian Gienger ◽  
Melina Dilanas ◽  
Andreas Schnepf ◽  
Andreas-Neil Unterreiner
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Conduction Band ◽  
Near Infrared ◽  
Transient Absorption ◽  
Time Window ◽  
Excess Electron ◽  
Cluster Core ◽  
Relaxation Dynamics ◽  
Additional Time

We present a comprehensive femtosecond (fs) transient absorption study of the [Ge9(Hyp)3]− (Hyp = Si(SiMe3)3) cluster solvated in tetrahydrofuran (THF) with special emphasis on intra- and intermolecular charge transfer mechanisms which can be tuned by exchange of the counterion and by dimerization of the cluster. The examination of the visible and the near infrared (NIR) spectral range reveals four different processes of cluster dynamics after UV (267/258 nm) photoexcitation related to charge transfer to solvent and localized excited states in the cluster. The resulting transient absorption is mainly observed in the NIR region. In the UV-Vis range transient absorption of the (neutral) cluster core with similar dynamics can be observed. By transferring concepts of: (i) charge transfer to the solvent known from solvated Na− in THF and (ii) charge transfer in bulk-like materials on metalloid cluster systems containing [Ge9(Hyp)3]− moieties, we can nicely interpret the experimental findings for the different compounds. The first process occurs on a fs timescale and is attributed to localization of the excited electron in the quasi-conduction band/excited state which competes with a charge transfer to the solvent. The latter leads to an excess electron initially located in the vicinity of the parent cluster within the same solvent shell. In a second step, it can recombine with the cluster core with time constants in the picosecond (ps) timescale. Some electrons can escape the influence of the cluster leading to a solvated electron or after interaction with a cation to a contact pair both with lifetimes exceeding our experimentally accessible time window of 1 nanosecond (ns). An additional time constant on a tens of ps timescale is pronounced in the UV-Vis range which can be attributed to the recombination rate of the excited state or quasi conduction band of Ge9−. In the dimer, the excess electron cannot escape the molecule due to strong trapping by the Zn cation that links the two cluster cores.

scholarly journals Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

2020 ◽  
Vol 16 ◽  
pp. 1066-1074 ◽  
Author(s):  
Nuray Altinolcek ◽  
Ahmet Battal ◽  
Mustafa Tavasli ◽  
William J Peveler ◽  
Holly A Yu ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Intramolecular Charge Transfer ◽  
Amorphous Solids ◽  
Reduction Peak ◽  
Energy Bands ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Positive Potential ◽  
Irreversible Reduction ◽  
Absorption And Emission Spectroscopy

Two novel carbazole-based compounds 7a and 7b were synthesised as potential candidates for application in organic electronics. The materials were fully characterised by NMR spectroscopy, mass spectrometry, FTIR, thermogravimetric analysis, differential scanning calorimetry, cyclic voltammetry, and absorption and emission spectroscopy. Compounds 7a and 7b, both of which were amorphous solids, were stable up to 291 °C and 307 °C, respectively. Compounds 7a and 7b show three distinctive absorption bands: high and mid energy bands due to locally excited (LE) transitions and low energy bands due to intramolecular charge transfer (ICT) transitions. In dichloromethane solutions compounds 7a and 7b gave emission maxima at 561 nm and 482 nm with quantum efficiencies of 5.4% and 97.4% ± 10%, respectively. At positive potential, compounds 7a and 7b gave two different oxidation peaks, respectively: quasi-reversible at 0.55 V and 0.71 V, and reversible at 0.84 V and 0.99 V. At negative potentials, compounds 7a and 7b only exhibited an irreversible reduction peak at −1.86 V and −1.93 V, respectively.

scholarly journals Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiao Luo ◽  
Yaoyao Han ◽  
Zongwei Chen ◽  
Yulu Li ◽  
Guijie Liang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Organic Molecule ◽  
Transient Absorption ◽  
High Energy ◽  
Model Systems ◽  
Trap States ◽  
Triplet Energy ◽  
Surface Trap ◽  
Triplet Energy Transfer

AbstractThe mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface remain poorly understood. Many seemingly contradictory results have been reported, mainly because of the complicated trap states characteristic of inorganic semiconductors and the ill-defined relative energetics between semiconductors and molecules used in these studies. Here we clarify the transfer mechanisms by performing combined transient absorption and photoluminescence measurements, both with sub-picosecond time resolution, on model systems comprising lead halide perovskite nanocrystals with very low surface trap densities as the triplet donor and polyacenes which either favour or prohibit charge transfer as the triplet acceptors. Hole transfer from nanocrystals to tetracene is energetically favoured, and hence triplet transfer proceeds via a charge separated state. In contrast, charge transfer to naphthalene is energetically unfavourable and spectroscopy shows direct triplet transfer from nanocrystals to naphthalene; nonetheless, this “direct” process could also be mediated by a high-energy, virtual charge-transfer state.

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