scholarly journals Remarkable Increase of Fluorescence Quantum Efficiency by Cyano Substitution on an ESIPT Molecule 2-(2-Hydroxyphenyl)benzothiazole: A Highly Photoluminescent Liquid Crystal Dopant

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1105
Author(s):  
Tsuneaki Sakurai ◽  
Masaya Kobayashi ◽  
Hiroyuki Yoshida ◽  
Masaki Shimizu
Keyword(s):  
Liquid Crystal ◽  
Excited State ◽  
Solid State ◽  
Room Temperature ◽  
Cyano Group ◽  
Stokes Shift ◽  
Phenyl Group ◽  
Intramolecular Proton Transfer ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields

Fluorescent molecules with excited-state intramolecular proton transfer (ESIPT) character allow the efficient solid-state luminescence with large Stokes shift that is important for various applications, such as organic electronics, photonics, and bio-imaging fields. However, the lower fluorescence quantum yields (ΦFL) in the solution or viscous media, due to their structural relaxations in the excited state to reach the S0/S1 conical intersection, shackle further applications of ESIPT-active luminophores. Here we report that the introduction of a cyano group (-CN) into the phenyl group of 2-(2-hydroxyphenyl)benzothiazole (HBT), a representative ESIPT compound, remarkably increase its fluorescence quantum yield (ΦFL) from 0.01 (without -CN) to 0.49 (with -CN) in CH2Cl2, without disturbing its high ΦFL (=0.52) in the solid state. The large increase of the solution-state ΦFL of the cyano-substituted HBT (CN-HBT) is remarkable, comparing with our previously reported ΦFL values of 0.05 (with 4-pentylphenyl), 0.07 (with 1-hexynyl), and 0.15 (with 4-pentylphenylethynyl). Of interest, the newly-synthesized compound, CN-HBT, is miscible in a conventional room-temperature nematic liquid crystal (LC), 4-pentyl-4′-cyano biphenyl (5CB), up to 1 wt% (~1 mol%), and exhibits a large ΦFL of 0.57 in the viscous LC medium. A similar ΦFL value of ΦFL = 0.53 was also recorded in another room-temperature LC, trans-4-(4-pentylcyclohexyl)benzonitrile (PCH5), with a doping ratio of 0.5 wt% (~0.5 mol%). These 5CB/CN-HBT and PCH5/CN-HBT mixtures serve as light-emitting room-temperature LCs, and show anisotropic fluorescence with the dichroic ratio of 3.1 upon polarized excitation, as well as electric field response of luminescence intensity changes.

scholarly journals Nitrile-Substituted 2-(Oxazolinyl)-Phenols: Minimalistic Excited-State Intramolecular Proton Transfer (ESIPT)-Based Fluorophores

2020 ◽  
Author(s):  
Dominik Göbel ◽  
Daniel Duvinage ◽  
Tim Stauch ◽  
Boris Nachtsheim
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
Crystal Structure Analysis ◽  
Quantum Yields ◽  
Functional Theory ◽  
Emission Properties ◽  
Emission Enhancement

Herein, we present minimalistic single-benzene, excited-state intramolecular proton transfer (ESIPT) based fluorophores as powerful solid state emitters. The very simple synthesis gave access to all four regioisomers of nitrile-substituted 2(oxazolinyl)phenols (MW = 216.1). In respect of their emission properties they can be divided into aggregation-induced emission enhancement (AIEE) luminophores (1-CN and 2-CN), dual state emission (DSE) emitters (3-CN) and aggregation-caused quenching (ACQ) fluorophores (4‐CN). Remarkably, with compound 1-CN we discovered a minimalistic ESIPT based fluorophore with extremely high quantum yield in the solid state ΦF = 87.3% at λem = 491 nm. Furthermore, quantum yields in solution were determined up to ΦF = 63.0%, combined with Stokes shifts up till 11.300 cm–1. Temperature dependent emission mapping, crystal structure analysis and time-dependent density functional theory (TDDFT) calculations gave deep insight into the origin of the emission properties.<br>

The influence of phenylethynyl linkers on the photo-physical properties of metal-free porphyrins

2000 ◽  
Vol 04 (07) ◽  
pp. 669-683 ◽  
Author(s):  
GARY A. BAKER ◽  
FRANK V. BRIGHT ◽  
MICHAEL R. DETTY ◽  
SIDDHARTH PANDEY ◽  
COREY E. STILTS ◽  
...  
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Phenyl Group ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
Strongly Coupled ◽  
Metal Free ◽  
Fluorescence Quantum Yields ◽  
Porphyrin Core ◽  
Absorbance Spectra

Series of 5,10,15,20-tetraarylporphyrins 1 and 5,10,15,20-tetrakis[4-(arylethynyl)phenyl]porphyrins 2 were prepared via condensation of pyrrole with the appropriate benzaldehyde or 4-(arylethynyl)benzaldehyde derivative (3). Condensation of meso-phenyldipyrromethane with mixtures of benzaldehyde and 4-(trimethylsilyl-ethynyl)benzaldehyde gave a separable mixture of mono- (6), bis- (both cis-7 and trans-8) and tris[4-(trimethylsilylethynyl)phenyl]porphyrin (9). Following removal of the trimethylsilyl groups of 6–9, the 4-ethynylphenyl groups of 11–14 were coupled to 1-iodo-3,5-di(trifluoromethyl)benzene with Pd ( OAc )2 to give 15–18 bearing one, two (both cis- and trans-) and three 4-[bis-3,5-(trifluoromethyl)phenylethynyl]phenyl groups respectively. Coupling of 11 and 1-iodo-4-nitrobenzene with Pd ( OAc )2 gave porphyrin 19 with one 4-(4-nitrophenylethynyl)phenyl group. Porphyrin 24 with a p-quinone linked to the porphyrin core via a phenylethynyl group was prepared via similar chemistry. The absorbance spectra, emission maxima, excited-state fluorescence lifetimes, quantum yields of fluorescence, rates of fluorescence and rates of non-radiative decay were measured for each of the porphyrins. Absorbance spectra and emission maxima were nearly identical for all the porphyrins of this study, which suggests that the aryl groups and 4-(arylethynyl)phenyl groups are not strongly coupled to the porphyrin core in these metal-free compounds. Fluorescence quantum yields and rates of radiative decay were larger for porphyrins bearing 4-(arylethynyl)phenyl groups, while excited-state fluorescence lifetimes were somewhat shorter. These effects were additive for each additional 4-(arylethynyl)phenyl group.

Structure Property Analysis of the Solution and Solid-State Properties of Bistable Photochromic Hydrazones

2019 ◽  
Author(s):  
Baihao Shao ◽  
Hai Qian ◽  
Quan Li ◽  
ivan aprahamian
Keyword(s):  
Solid State ◽  
Phenyl Group ◽  
Quantum Yields ◽  
Structure Property ◽  
Pull System ◽  
X Ray Crystallography ◽  
Fluorescence Quantum Yields ◽  
Property Analysis ◽  
Fluorescence Characteristics ◽  
Almost All

The development of new photochromic compounds, and the optimization of their photophysical and switching properties are prerequisites for accessing new functions and opportunities that are not possible with currently available systems. To this end we recently developed a new bistable hydrazone switch that undergoes efficient photoswitching and emission ON/OFF toggling in both solution and solid-state. Here, we present a systematic structure-property analysis using a family of hydrazones, and show how their properties, including activation wavelengths, photostationary states (PSSs), photoisomerization quantum yields, thermal half-lives (<i>t</i><sub>1/2</sub>), and solution/solid-state fluorescence characteristics vary as a function of electron donating (EDG) and/or withdrawing (EWG) substituents. These studies resulted in the red-shifting of the absorption profiles of the <i>Z</i> and <i>E</i> isomers of the switches, while maintaining excellent PSSs in almost all of the compounds. The introduction of <i>para</i>-NMe<sub>2</sub>, and/or <i>para</i>-NO<sub>2</sub> groups improved the photoisomerization quantum yields, and the extremely long thermal half-lives (tens to thousands of years) were maintained in most cases, even in a push-pull system, which can be activated solely with visible light. Hydrazones bearing EDGs at the stator phenyl group are an exception and show up to 6 orders of magnitude acceleration in<i>t</i><sub>1/2 </sub>(<i>i.e.</i>, days)<sub> </sub>because of a change in the isomerization mechanism. Moreover, we discovered that a <i>para</i>-NMe<sub>2</sub> group is required to have reasonable fluorescence quantum yields in solution, and that rigidification enhances the emission in the solid-state. Finally, X-ray crystallography analysis showed that the switching process is more efficient in the solid-state when the hydrazone is loosely packed.<br>

scholarly journals Facile Synthesis of an Organic Solid State Near-Infrared-Emitter with Large Stokes Shift via Excited-State Intramolecular Proton Transfer

ACS Omega ◽  
2018 ◽  
Vol 3 (10) ◽  
pp. 14341-14348 ◽  
Author(s):  
Abhishek Kumar Gupta ◽  
Ashwani Kumar ◽  
Ranjit Singh ◽  
Manisha Devi ◽  
Abhimanew Dhir ◽  
...  
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Near Infrared ◽  
Stokes Shift ◽  
Intramolecular Proton Transfer ◽  
Facile Synthesis ◽  
Large Stokes Shift ◽  
Organic Solid ◽  
Infrared Emitter

Structure Property Analysis of the Solution and Solid-State Properties of Bistable Photochromic Hydrazones

2019 ◽  
Author(s):  
Baihao Shao ◽  
Hai Qian ◽  
Quan Li ◽  
ivan aprahamian
Keyword(s):  
Solid State ◽  
Phenyl Group ◽  
Quantum Yields ◽  
Structure Property ◽  
Pull System ◽  
X Ray Crystallography ◽  
Fluorescence Quantum Yields ◽  
Property Analysis ◽  
Fluorescence Characteristics ◽  
Almost All

The development of new photochromic compounds, and the optimization of their photophysical and switching properties are prerequisites for accessing new functions and opportunities that are not possible with currently available systems. To this end we recently developed a new bistable hydrazone switch that undergoes efficient photoswitching and emission ON/OFF toggling in both solution and solid-state. Here, we present a systematic structure-property analysis using a family of hydrazones, and show how their properties, including activation wavelengths, photostationary states (PSSs), photoisomerization quantum yields, thermal half-lives (<i>t</i><sub>1/2</sub>), and solution/solid-state fluorescence characteristics vary as a function of electron donating (EDG) and/or withdrawing (EWG) substituents. These studies resulted in the red-shifting of the absorption profiles of the <i>Z</i> and <i>E</i> isomers of the switches, while maintaining excellent PSSs in almost all of the compounds. The introduction of <i>para</i>-NMe<sub>2</sub>, and/or <i>para</i>-NO<sub>2</sub> groups improved the photoisomerization quantum yields, and the extremely long thermal half-lives (tens to thousands of years) were maintained in most cases, even in a push-pull system, which can be activated solely with visible light. Hydrazones bearing EDGs at the stator phenyl group are an exception and show up to 6 orders of magnitude acceleration in<i>t</i><sub>1/2 </sub>(<i>i.e.</i>, days)<sub> </sub>because of a change in the isomerization mechanism. Moreover, we discovered that a <i>para</i>-NMe<sub>2</sub> group is required to have reasonable fluorescence quantum yields in solution, and that rigidification enhances the emission in the solid-state. Finally, X-ray crystallography analysis showed that the switching process is more efficient in the solid-state when the hydrazone is loosely packed.<br>

scholarly journals Nitrile-Substituted 2-(Oxazolinyl)-Phenols: Minimalistic Excited-State Intramolecular Proton Transfer (ESIPT)-Based Fluorophores

2020 ◽  
Author(s):  
Dominik Göbel ◽  
Daniel Duvinage ◽  
Tim Stauch ◽  
Boris Nachtsheim
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
Crystal Structure Analysis ◽  
Quantum Yields ◽  
Functional Theory ◽  
Emission Properties ◽  
Emission Enhancement

Herein, we present minimalistic single-benzene, excited-state intramolecular proton transfer (ESIPT) based fluorophores as powerful solid state emitters. The very simple synthesis gave access to all four regioisomers of nitrile-substituted 2(oxazolinyl)phenols (MW = 216.1). In respect of their emission properties they can be divided into aggregation-induced emission enhancement (AIEE) luminophores (1-CN and 2-CN), dual state emission (DSE) emitters (3-CN) and aggregation-caused quenching (ACQ) fluorophores (4‐CN). Remarkably, with compound 1-CN we discovered a minimalistic ESIPT based fluorophore with extremely high quantum yield in the solid state ΦF = 87.3% at λem = 491 nm. Furthermore, quantum yields in solution were determined up to ΦF = 63.0%, combined with Stokes shifts up till 11.300 cm–1. Temperature dependent emission mapping, crystal structure analysis and time-dependent density functional theory (TDDFT) calculations gave deep insight into the origin of the emission properties.<br>

scholarly journals The development of aryl-substituted 2-phenylimidazo[1,2-a]pyridines (PIP) with various colors of excited-state intramolecular proton transfer (ESIPT) luminescence in the solid state

2016 ◽  
Vol 4 (16) ◽  
pp. 3599-3606 ◽  
Author(s):  
Toshiki Mutai ◽  
Tatsuya Ohkawa ◽  
Hideaki Shono ◽  
Koji Araki
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Aryl Group ◽  
Red Emission ◽  
Wide Range

The color of ESIPT luminescence of HPIP is tuned in a wide range by the introduction of aryl group(s), and thus a series of PIPs showing blue to red emission is realized.

scholarly journals Indenopyrans – synthesis and photoluminescence properties

2016 ◽  
Vol 12 ◽  
pp. 825-834 ◽  
Author(s):  
Andreea Petronela Diac ◽  
Ana-Maria Ţepeş ◽  
Albert Soran ◽  
Ion Grosu ◽  
Anamaria Terec ◽  
...  
Keyword(s):  
Solid State ◽  
Emission Band ◽  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Band Broadening ◽  
Photoluminescence Properties ◽  
Fluorescence Quantum Yields ◽  
Blue Emitters ◽  
Solid State Fluorescence

New indeno[1,2-c]pyran-3-ones bearing different substituents at the pyran moiety were synthesized and their photophysical properties were investigated. In solution all compounds were found to be blue emitters and the trans isomers exhibited significantly higher fluorescence quantum yields (relative to 9,10-diphenylanthracene) as compared to the corresponding cis isomers. The solid-state fluorescence spectra revealed an important red shift of λmax due to intermolecular interactions in the lattice, along with an emission-band broadening, as compared to the solution fluorescence spectra.

Substitution Effect on 2-(Oxazolinyl)-phenols: Emission Color-Tunable, Minimalistic Excited-State Intramolecular Proton Transfer (ESIPT)-based Luminophores

2021 ◽  
Author(s):  
Dominik Göbel ◽  
Pascal Rusch ◽  
Daniel Duvinage ◽  
Tim Stauch ◽  
Nadja C. Bigall ◽  
...  
Keyword(s):  
Optical Properties ◽  
Excited State ◽  
Solid State ◽  
Substitution Effect ◽  
Optical Characterization ◽  
Intramolecular Proton Transfer ◽  
Substitution Pattern ◽  
Emission Color ◽  
Color Tunable

The synthesis and optical characterization of novel single-benzene ESIPT-based fluorophores is described in solid state and in solution. Special attention is given towards the influence of their unique substitution pattern on their optical properties. Depending on this pattern, aggregation induced emission or aggregation caused quenching (ACQ) is observed in the solid state.<br>

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