scholarly journals Structure–property relationships in aromatic thioethers featuring aggregation-induced emission: solid-state structures and theoretical analysis

CrystEngComm ◽  
2019 ◽  
Vol 21 (19) ◽  
pp. 3097-3105 ◽  
Author(s):  
Marco Saccone ◽  
Steffen Riebe ◽  
Jacqueline Stelzer ◽  
Christoph Wölper ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Solid State ◽  
Theoretical Analysis ◽  
Quantum Yields ◽  
Structure Property ◽  
Aggregation Induced Emission ◽  
Π Interactions ◽  
Fluorescence Quantum Yields ◽  
Structure Property Relationships ◽  
Solid State Structures

The evolution of the fluorescence quantum yields was correlated with the increase of C–H⋯π and the decrease of π⋯π interactions in the solid state.

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 Molecular and Crystalline Requirements for Solid State Fluorescence Exploiting Excited State Intramolecular Proton Transfer

2019 ◽  
Author(s):  
Michael Dommett ◽  
Miguel Rivera ◽  
Matthew T. H. Smith ◽  
Rachel Crespo Otero
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Extensive Study ◽  
Structure Property ◽  
Aggregation Induced Emission ◽  
Organic Systems ◽  
Structure Property Relationships ◽  
Formidable Challenge

Aggregation induced emission offers a route to the development of emissive technologies based on solely organic systems. However, maximising fluorescence quantum efficiencies (QE) is a formidable challenge in attaining first-principles materials design, due to the interplay between the electronic structure of the chromophore and the molecular crystal. The identification of radiative and nonradiative channels, and how these are affected by aggregation, can rationalise the emissive properties of materials and aid in the design of yet more efficient fluorophores. In the current work, we examine the mechanism behind aggregation induced emission in two related families of compounds with lasing properties, which undergo excited state intramolecular proton transfer (ESIPT). We systematically investigate competing excited state decay channels in a total of eleven crystals to evaluate the factors needed for efficient ESIPT fluorophores, aided by a full evaluation of the crystal structures, exciton coupling, and exciton hopping rates. We show that in addition to the restriction of nonradiative pathways, an efficient ESIPT is essential to maximise the QE in the solid state. This extensive study of structure-property relationships for fluorophores based on the ESIPT mechanism bridges the understanding of molecular photophysics with crystal structure, accelerating the development of highly efficient solid state emitters.

Aza boron-pyridyl-isoindoline isomers: synthesis and photophysical properties

2014 ◽  
Vol 18 (08n09) ◽  
pp. 679-685 ◽  
Author(s):  
Hui Liu ◽  
Yanping Wu ◽  
Zhifang Li ◽  
Hua Lu
Keyword(s):  
Photophysical Properties ◽  
Emission Spectra ◽  
Quantum Yields ◽  
Structure Property ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fluorescence Quantum Yields ◽  
Structure Property Relationships ◽  
New Type ◽  
Vibrational Bands

By changing benzo-fused position on pyridyl unit, three aza boron-pyridyl-isoindoline isomers, a new type of BODIPY analog, are synthesized through a facile two step reaction. These isomers show broad envelopes of intense vibrational bands in the absorption and emission spectra with moderate fluorescence quantum yields. In comparison to those of classical BODIPYs, significant fluorescence intensity are observed for these isomers in film and powder. An analysis of the structure-property relationships has been carried out based on X-ray crystallography, optical spectroscopy, and theoretical calculation.

scholarly journals Molecular and Crystalline Requirements for Solid State Fluorescence Exploiting Excited State Intramolecular Proton Transfer

2019 ◽  
Author(s):  
Michael Dommett ◽  
Miguel Rivera ◽  
Matthew T. H. Smith ◽  
Rachel Crespo Otero
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Extensive Study ◽  
Structure Property ◽  
Aggregation Induced Emission ◽  
Organic Systems ◽  
Structure Property Relationships ◽  
Formidable Challenge

Aggregation induced emission offers a route to the development of emissive technologies based on solely organic systems. However, maximising fluorescence quantum efficiencies (QE) is a formidable challenge in attaining first-principles materials design, due to the interplay between the electronic structure of the chromophore and the molecular crystal. The identification of radiative and nonradiative channels, and how these are affected by aggregation, can rationalise the emissive properties of materials and aid in the design of yet more efficient fluorophores. In the current work, we examine the mechanism behind aggregation induced emission in two related families of compounds with lasing properties, which undergo excited state intramolecular proton transfer (ESIPT). We systematically investigate competing excited state decay channels in a total of eleven crystals to evaluate the factors needed for efficient ESIPT fluorophores, aided by a full evaluation of the crystal structures, exciton coupling, and exciton hopping rates. We show that in addition to the restriction of nonradiative pathways, an efficient ESIPT is essential to maximise the QE in the solid state. This extensive study of structure-property relationships for fluorophores based on the ESIPT mechanism bridges the understanding of molecular photophysics with crystal structure, accelerating the development of highly efficient solid state emitters.

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 Perylene Bisimide Cyclophanes: Structure–Property Relationships upon Variation of the Cavity Size

2020 ◽  
Vol 02 (02) ◽  
pp. 149-158 ◽  
Author(s):  
Jessica Rühe ◽  
David Bialas ◽  
Peter Spenst ◽  
Ana-Maria Krause ◽  
Frank Würthner
Keyword(s):  
Dipole Approximation ◽  
Quantum Yields ◽  
Point Dipole ◽  
Structure Property ◽  
Perylene Bisimide ◽  
Fluorescence Quantum Yields ◽  
Exciton Coupling ◽  
Structure Property Relationships ◽  
Point Dipole Approximation ◽  
Coupling Strengths

Five cyclophanes composed of two perylene bisimide (PBI) dyes and various CH2–arylene–CH2 linker units were synthesized. PM6-D3H4 geometry-optimized structures and a single crystal for one of these cyclophanes reveal well-defined distances between the two coplanar PBI units in these cyclophanes, spanning the range from 5.0 to 12.5 Å. UV/vis absorption spectra reveal a redistribution of oscillator strength of the vibronic bands due to a H-type exciton coupling even for the cyclophane with the largest interchromophoric distance. A quantitative evaluation according to the Kasha–Spano theory affords exciton coupling strengths ranging from 64 cm−1 for the largest cyclophane up to 333 cm−1 for the smallest one and a surprisingly good fit to the cubic interchromophoric distance in the framework of the point-dipole approximation. Interchromophoric interaction is also noticed in fluorescence lifetimes that are significantly increased for all five cyclophanes as expected for H-coupled chromophores due to a decrease of the radiative rate. For the three largest cyclophanes with interchromophoric distances of >9 Å, fluorescence quantum yields remain high in chloroform (>88%), whilst for the smaller ones with interchromophoric distances <6 Å, additional nonradiative pathways lead to a pronounced fluorescence quenching.

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.

scholarly journals Towards Blue AIE/AIEE: Synthesis and Applications in OLEDs of Tetra-/Triphenylethenyl Substituted 9,9-Dimethylacridine Derivatives

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 445 ◽  
Author(s):  
Monika Cekaviciute ◽  
Aina Petrauskaite ◽  
Sohrab Nasiri ◽  
Jurate Simokaitiene ◽  
Dmytro Volyniuk ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Yields ◽  
Yellow Emission ◽  
Blue Color ◽  
Television System ◽  
Fluorescence Quantum Yields ◽  
Deep Blue ◽  
Wide Range ◽  
Cyano Groups ◽  
High Yields

Aiming to design blue fluorescent emitters with high photoluminescence quantum yields in solid-state, nitrogen-containing heteroaromatic 9,9-dimethylacridine was refined by tetraphenylethene and triphenylethene. Six tetra-/triphenylethene-substituted 9,9-dimethylacridines were synthesized by the Buchwald-Hartwig method with relatively high yields. Showing effects of substitution patterns, all emitters demonstrated high fluorescence quantum yields of 26–53% in non-doped films and 52–88% in doped films due to the aggregation induced/enhanced emission (AIE/AIEE) phenomena. In solid-state, the emitters emitted blue (451–481 nm) without doping and deep-blue (438–445 nm) with doping while greenish-yellow emission was detected for two compounds with additionally attached cyano-groups. The ionization potentials of the derivatives were found to be in the relatively wide range of 5.43–5.81 eV since cyano-groups were used in their design. Possible applications of the emitters were demonstrated in non-doped and doped organic light-emitting diodes with up to 2.3 % external quantum efficiencies for simple fluorescent devices. In the best case, deep-blue electroluminescence with chromaticity coordinates of (0.16, 0.10) was close to blue color standard (0.14, 0.08) of the National Television System Committee.

scholarly journals Barbituric Acid Based Fluorogens: Synthesis, Aggregation-Induced Emission, and Protein Fibril Detection

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 32 ◽  
Author(s):  
Siyang Ding ◽  
Bicheng Yao ◽  
Louis Schobben ◽  
Yuning Hong
Keyword(s):  
Barbituric Acid ◽  
Fluorescent Dyes ◽  
Photophysical Properties ◽  
Wavelength Region ◽  
Structure Property ◽  
Aggregation Induced Emission ◽  
Long Wavelength ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Protein Fibril

Fluorescent dyes, especially those emitting in the long wavelength region, are excellent candidates in the area of bioassay and bioimaging. In this work, we report a series of simple organic fluorescent dyes consisting of electron-donating aniline groups and electron-withdrawing barbituric acid groups. These dyes are very easy to construct while emitting strongly in the red region in their solid state. The photophysical properties of these dyes, such as solvatochromism and aggregation-induced emission, are systematically characterized. Afterward, the structure–property relationships of these barbituric acid based fluorogens are discussed. Finally, we demonstrate their potential applications for protein amyloid fibril detection.

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