Organic Fluorophores Derived From Pyrazoline for Plastic Scintillators Valery N. Bliznyuk, Ayman Seliman, Timothy DeVolDepartment of Environmental Engineering and Earth Science, Clemson University, Clemson, SC 29634 USA

Nadezhda A. Derevyanko, Alexander A. Ishchenko

Institute of Organic Chemistry, National Academy of Science of Ukraine, Kiev, Ukraine

LSC 2017, Copenhagen, DenmarkMay 1-5, 2017

Application to Water Monitoring

Decreased performance of Sr ScintEx resin

Efficient Scintillation Detection

High absorptivity for high energy electromagnetic radiation or particles, e.g. in UV and deep UV

Efficient Förster resonance energy transfer (FRET) Efficient harvesting of the absorbed energy and its concentration on the

emitting centers

High quantum yield – i.e., the ratio of the # of emitted photons to the # of absorbed photons

Large Stokes Shift – to minimize self-absorption Maximum of the emission wavelength to match the maximum

absorption wavelength of photodetector typically achieved by application of a mixture of primary and

secondary fluorophores Optical transparency in visible range High stability of properties under harsh conditions of chemical,

radiation, light and temperature exposure

Pyrazoline and its derivatives

1,3,5-triphenyl-2-pyrazolinehttp://www.chemspider.com/ImageView.aspx?mode=3d&id=86609

Pyrazoline core

Synthesis of PZ compounds

Simple

Uses common compounds

High yield

Can be scaled upto industrial level

V.N.Bliznyuk et al, ACS Applied Materials & Interfaces, 2016, 8, 12843

Characterization

• 1H NMR • Raman

Absorption and Emission Spectra

vPZ1PZ1

Fluorescence quantum yield Φfof PZ fluorophores relative to 9,10-Diphenylanthracene (DPA)

FluorophoreΦf %

Cyclohexane Toluene

PZ1 109 116vPZ1 74 79PZ2 107 114PZ3 111 116

0.5% vPZ1 0.5% vPZ1 3% vNPO

Laser = 30.0% Laser = 100.0%Laser = 5.0%

Confocal laser microscopy

Quantum Yield and Fluorescence Spectroscopy

Radioluminosity

Luminosity spectra of PVT beadscontaining (a) vPZ1 or (b) vNPO (αNPO)fluorophores depending on the fluorophoreconcentration.

Radioluminosity Measurement

0.5%

Energydepositionevent

Emission of light

excitationof fluor

Nanostructured design for efficient energy harvesting

~10 nm or ~ 30 monomer units

fluor

V.N.Bliznyuk et al, ACS Applied Materials & Interfaces, 2016, 8, 12843

Covalently bound fluor:● Reduced aggregation● Coupling to the matrix● Chemical stability

radiative or nonradiative energy transfer

NN

Br

> 10-5 Mfluorophore concentration

NN

NN

1

2

34

5

HN

N HN

N12

3

Quantum Mechanical Modeling

Main Features:• “Two in one” chromophore with non-planar “3D antenna”

structure

• Simultaneous primary and secondary fluorophore action

• Reduced aggregation and enhanced coupling with the matrix

• Concentration can be reduced close to the theoretical minimum

1,3,5-triphenyl-2-pyrazoline (TPhH)

Phenylhydrazine benzaldehyde (PhHB)

Chromophore II

Chromophore I

Conclusions

1,3,5-triphenyl-2-pyrazol

- Hetero-substituted PZ derivatives are soluble in common organic solvents and therefore can be incorporated in a polymer matrix

- 3 times higher fluorescence

- ~10% higher radioluminosity in comparison to existing analogs

- 10% higher Quantum Yield

- Enhanced stability0

1000

2000

3000

4000

5000

6000

7000

8000

0 100 200 300 400 500 600 700

Cou

nts

Channel

0.1% vPZ1

0.5% vPZ1

0.1% NPOα

Acknowledgements

Funding from the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-12-1-0012