scholarly journals Time-Resolved Spectroscopic Study of N,N–Di(4–bromo)nitrenium Ions in Acidic Aqueous Solution

2019 ◽  
Vol 20 (21) ◽  
pp. 5512 ◽  
Author(s):  
Lili Du ◽  
Zhiping Yan ◽  
Xueqin Bai ◽  
Runhui Liang ◽  
David Lee Phillips
Keyword(s):  
Aqueous Solution ◽  
Transient Absorption ◽  
Function Theory ◽  
Spectroscopic Properties ◽  
Time Resolved ◽  
Nitrenium Ions ◽  
Acidic Aqueous Solution ◽  
Nitrenium Ion ◽  
Femtosecond Transient Absorption ◽  
Aqueous Conditions

Nitrenium ions are common reactive intermediates with high activities towards some biological nucleophiles. In this paper, we employed femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) as well as nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy and density function theory (DFT) calculations to study the spectroscopic properties of the N(4,4′–dibromodiphenylamino)–2,4,6–trimethylpyridinium BF4− salt (1) in an acidic aqueous solution. Efficient cleavage of the N–N bond (4 ps) to form the N,N–di(4–bromophenyl)nitrenium ion (DN) was also observed in the acidic aqueous solution. As a result, the dication intermediate 4 appears more likely to be produced after abstracting a proton for the nitrenium ion DN in the acid solution first, followed by an electron abstraction to form the radical cation intermediate 3. These new and more extensive time-resolved spectroscopic data will be useful to help to develop an improved understanding of the identity, nature, and properties of nitrenium ions involved in reactions under acidic aqueous conditions.

scholarly journals Time-Resolved Spectroscopic Study of N,N-Di(4-bromo)nitrenium Ions in Selected Solutions

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3182 ◽  
Author(s):  
Lili Du ◽  
Xin Lan ◽  
Zhiping Yan ◽  
Ruixue Zhu ◽  
David Phillips
Keyword(s):  
Transient Absorption ◽  
Direct Detection ◽  
Reaction Pathway ◽  
Addition Reactions ◽  
Time Resolved ◽  
Nitrenium Ions ◽  
Future Studies ◽  
Nitrenium Ion ◽  
Design Time

Nitrenium ions are important reactive intermediates in chemistry and biology. In this work, femtosecond and nanosecond transient absorption (fs-TA and ns-TA) along with nanosecond time-resolved resonance Raman (ns-TR3) experiments were employed to examine the photochemical pathways of N-(4,4′-dibromodiphenylamino)-2,4,6-trimethylpyridinium BF4− (salt (DN) from just absorption of a photon of light to the production of the important N,N-di(4-bromophenyl)nitrenium ion 2. In acetonitrile (MeCN), the formation of halogenated diarylnitrenium ion 2 was observed within 4 ps, showing the vibrational spectra with strong intensity. The nucleophilic adduct reaction of ion 2 with H2O was also examined in aqueous solutions. The direct detection of the unique ortho adduct intermediate 3 shows that there is an efficient and exclusive reaction pathway for 2 with H2O. The results shown in this paper give new characterization of 2, which can be used to design time-resolved spectroscopy investigations of covalent addition reactions of nitrenium ions with other molecules in future studies.

Charge carrier kinetics of carbon nitride colloid: a femtosecond transient absorption spectroscopy study

2016 ◽  
Vol 18 (22) ◽  
pp. 14904-14910 ◽  
Author(s):  
Huiyu Zhang ◽  
Yaping Chen ◽  
Rong Lu ◽  
Ruiyu Li ◽  
Anchi Yu
Keyword(s):  
Charge Carrier ◽  
Carbon Nitride ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Spectroscopy Study ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Femtosecond Transient Absorption ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Kinetics Of

The charge carrier kinetics of carbon nitride colloid was investigated using a combination of femtosecond transient absorption and picosecond time-resolved fluorescence spectroscopy.

EMI Series Mechanistic Investigation of a Visible Light Mediated Dehalogenation/Cyclisation Reaction using Iron(III), Iridium(III) and Ruthenium(II) Photosensitizers

2021 ◽  
Author(s):  
Akin Aydogan ◽  
Rachel Bangle ◽  
Simon De Kreijger ◽  
John Dickenson ◽  
Michael L Singleton ◽  
...  
Keyword(s):  
Steady State ◽  
Visible Light ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Time Resolved ◽  
Femtosecond Transient Absorption ◽  
Mechanistic Investigation ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Visible Light Driven ◽  
Time Resolved Infrared Spectroscopy

The mechanism of a visible light-driven dehalogenation/cyclization reaction was investigated using ruthenium(II), iridium(III) and iron(III) photosensitizers by means of steady-state photoluminescence, time-resolved infrared spectroscopy, and nanosecond/femtosecond transient absorption spectroscopy. The...

scholarly journals Ultrafast spectroscopy reveals singlet fission, ionization and excimer formation in perylene film

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenjun Ni ◽  
Licheng Sun ◽  
Gagik G. Gurzadyan
Keyword(s):  
Radical Cation ◽  
Transient Absorption ◽  
Photovoltaic Devices ◽  
Singlet Fission ◽  
Time Resolved ◽  
Singlet Exciton ◽  
Femtosecond Transient Absorption ◽  
Photovoltaic Applications ◽  
Singlet Exciton Fission ◽  
Triplet Formation

AbstractSinglet exciton fission (SF) is a spin-allowed process whereby two triplet excitons are created from one singlet exciton. This phenomenon can offset UV photon energy losses and enhance the overall efficiency in photovoltaic devices. For this purpose, it requires photostable commercially available SF materials. Excited state dynamics in pure perylene film, ease of commercial production, is studied by time-resolved fluorescence and femtosecond transient absorption techniques under different photoexcitation energies. In film, polycrystalline regions contain perylene in H-type aggregate form. SF takes place from higher excited states of these aggregates in ultrafast time scale < 30 fs, reaching a triplet formation quantum yield of 108%. Moreover, at λex = 450 nm singlet fission was detected as a result of two-quantum absorption. Other competing relaxation channels are excimer (1 ps) and dimer radical cation formation (< 30 fs). Excimer radiatively relaxes within 19 ns and radical cation recombines in 3.2 ns. Besides, exciton self-trapping by crystal lattice distortions occurs within hundreds of picosecond. Our results highlight potential of simple-fabricated perylene films with similar properties as high-cost single crystal in SF based photovoltaic applications.

scholarly journals Photocarrier recombination dynamics in ternary chalcogenide CuInS2 quantum dots

2015 ◽  
Vol 17 (18) ◽  
pp. 11981-11989 ◽  
Author(s):  
Jianhui Sun ◽  
Michio Ikezawa ◽  
Xiuying Wang ◽  
Pengtao Jing ◽  
Haibo Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transient Absorption ◽  
Time Resolved ◽  
Ternary Chalcogenide ◽  
Femtosecond Transient Absorption ◽  
Cuins2 Quantum Dots ◽  
Time Resolved Photoluminescence ◽  
Recombination Dynamics

Photocarrier recombination dynamics in ternary chalcogenide CuInS2 quantum dots (CIS QDs) was studied by means of femtosecond transient-absorption (TA) and nanosecond time-resolved photoluminescence (PL) spectroscopy.

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