An X-band time domain electron paramagnetic resonance spectrometer

Das, Ranjan; Venkataraman, B.; Bhagat, Vinod R; Ghangrekar, Ajit; Kuruvilla, Thomas; Chaturvedi, B. K.; Isola, G S; Marwaha, B M; Nair, P. G.; Parolia, R S; Sarkar, B.

doi:10.1007/bf02845293

Cited by 15 publications

(5 citation statements)

References 16 publications

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“…Time‐resolved electron paramagnetic resonance spectroscopy : Both steady‐state and time‐resolved EPR measurements were carried out in a laboratory‐built X‐band spectrometer; its present version of the original design has been described earlier . The instrument response time is 75 ns.…”

Section: Methodsmentioning

confidence: 99%

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Wang

Gao

Hussain

et al. 2018

Chemistry A European J

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A compact naphthalenediimide (NDI)–2,2,6,6‐tetramethylpiperidinyloxy (TEMPO) dyad has been prepared with the aim of studying radical‐enhanced intersystem crossing (EISC) and the formation of high spin states as well as electron spin polarization (ESP) dynamics. Compared with the previously reported radical–chromophore dyads, the present system shows a very high triplet state quantum yield (ΦT=74 %), a long‐lived triplet state (τT=8.7 μs), fast EISC (1/kEISC=338 ps), and absorption in the red spectral region. Time‐resolved electron paramagnetic resonance (TREPR) spectroscopy showed that, upon photoexcitation in fluid solution at room temperature, the D0 state of the TEMPO moiety produces strong emissive (E) polarization owing to the quenching of the excited singlet state of NDI by the radical moiety (electron exchange J>0). The emissive polarization then inverts into absorptive (A) polarization within about 3 μs, and then relaxes to a thermal equilibrium while quenching the triplet state of NDI. The formation and decay of the quartet state were also observed. The dyad was used as a three‐spin triplet photosensitizer for triplet–triplet annihilation upconversion (quantum yield ΦUC=2.6 %). Remarkably, when encapsulated into liposomes, the red‐light‐absorbing dyad–liposomes show good biocompatibility and excellent photodynamic therapy efficiency (phototoxicity EC50=3.22 μm), and therefore is a promising candidate for future less toxic and multifunctional photodynamic therapeutic reagents.

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Section: Methodsmentioning

confidence: 99%

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Wang

Gao

Hussain

et al. 2018

Chemistry A European J

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“…10 m in dichloromethane) was placed in a glass tube, and degassed by repeated freezepump-thaw cycles with a vacuum line working at a pressure of about 10 -4 Torr., and then sealed off. This sealed sample was used for recording the CW-EPR spectrum at room temperature, using a home-built EPR spectrometer, [30] which was further modified. [31] Low microwave power (ca.…”

Section: Methodsmentioning

confidence: 99%

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OV^IV(μ‐O_oxo)(μ‐O_phen)V^VO]²⁺ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure

et al. 2006

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Binuclear mixed valence oxovanadium(IV/v) complexes of general formula [V2O3L] containing a [OVIV(μ‐Ooxo)(μ‐Ophen)VVO]2+ core have been synthesised using conformationally labile N4O3‐coordinating heptadentate ligands (H3L). The X‐ray structure of one complex has been examined. Solution EPR spectra revealed that the unpaired electron of the complexes is delocalised between the two vanadium centres. The simulated EPR spectrum of one complex confirms this experimental observation. DFT studies have been performed using crystallographic coordinates in order to obtain further insight into the electronic structure of this type of molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…Steady-state and time-resolved EPR spectra were recorded in a laboratory-built X-band electroparamagnetic resonance (EPR) spectrometer. 53 For the time-resolved EPR, the exciting source was the third harmonic of an Nd:YAG laser (Quantel Model: YG-981C, wavelength: 355 nm, repetition rate: 15 Hz, and energy at the sample: 1−4 mJ/pulse). Because of the extremely strong spin-polarized EPR signals, the laser energy was reduced to its lowest output value.…”

Section: Methodsmentioning

confidence: 99%

Spinning-Driven Dynamic Nuclear Polarization with Optical Pumping

et al. 2022

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We propose a new, more efficient, and potentially cost effective, solid-state nuclear spin hyperpolarization method combining the cross-effect mechanism and electron spin optical hyperpolarization in rotating solids. We first demonstrate optical hyperpolarization in the solid state at low temperatures and low field and then investigate its field dependence to obtain the optimal condition for high-field electron spin hyperpolarization. The results are then incorporated into advanced magic-angle spinning dynamic nuclear polarization (MAS-DNP) numerical simulations that show that optically pumped MAS-DNP could yield breakthrough enhancements at very high magnetic fields. Based on these investigations, enhancements greater than the ratio of electron to nucleus magnetic moments (>658 for 1H) are possible without microwave irradiation. This could solve at once the MAS-DNP performance decrease with increasing field and the high cost of MAS-DNP instruments at very high fields.

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An X-band time domain electron paramagnetic resonance spectrometer

Cited by 15 publications

References 16 publications

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OV^IV(μ‐O_oxo)(μ‐O_phen)V^VO]²⁺ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure

Spinning-Driven Dynamic Nuclear Polarization with Optical Pumping

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An X-band time domain electron paramagnetic resonance spectrometer

Cited by 15 publications

References 16 publications

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OVIV(μ‐Ooxo)(μ‐Ophen)VVO]2+ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure

Spinning-Driven Dynamic Nuclear Polarization with Optical Pumping

Contact Info

Product

Resources

About

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OV^IV(μ‐O_oxo)(μ‐O_phen)V^VO]²⁺ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure