scholarly journals Handed Mirror Symmetry Breaking at the Photo-Excited State of π-Conjugated Rotamers in Solutions

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 272 ◽  
Author(s):  
Puhup Puneet ◽  
Sajan Singh ◽  
Michiya Fujiki ◽  
Bhanu Nandan
Keyword(s):  
Symmetry Breaking ◽  
Parity Violation ◽  
Mirror Symmetry ◽  
Molecular Level ◽  
Time Resolved ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
Consistent Increase ◽  
Life On Earth ◽  
Time Resolved Photoluminescence

The quest to decode the evolution of homochirality of life on earth has stimulated research at the molecular level. In this study, handed mirror symmetry breaking, and molecular parity violation hypotheses of systematically designed π-conjugated rotamers possessing anthracene and bianthracene core were evinced via circularly polarized luminescence (CPL) and circular dichroism (CD). The CPL signals were found to exhibit a (−)-sign, and a handed dissymmetry ratio, which increased with viscosity of achiral solvents depending on the rotation barrier of rotamers. The time-resolved photoluminescence spectroscopy and quantum efficiency measurement of these luminophores in selected solvents reinforced the hypothesis of a viscosity-induced consistent increase of the (−)-sign handed CPL signals.

scholarly journals Questions of Mirror Symmetry at the Photoexcited and Ground States of Non-Rigid Luminophores Raised by Circularly Polarized Luminescence and Circular Dichroism Spectroscopy: Part 1. Oligofluorenes, Oligophenylenes, Binaphthyls and Fused Aromatics

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2606 ◽  
Author(s):  
Michiya Fujiki ◽  
Julian Koe ◽  
Takashi Mori ◽  
Yoshihiro Kimura
Keyword(s):  
Circular Dichroism ◽  
Mirror Symmetry ◽  
Neutral Current ◽  
Visible Region ◽  
Cd Spectroscopy ◽  
Mirror Image ◽  
Circularly Polarized ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
Circular Dichroïsm

We report experimental tests of whether non-rigid, π-conjugated luminophores in the photoexcited (S1) and ground (S0) states dissolved in achiral liquids are mirror symmetrical by means of circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopy. Herein, we chose ten oligofluorenes, eleven linear/cyclic oligo-p-arylenes, three binaphthyls and five fused aromatics, substituted with alkyl, alkoxy, phenyl and phenylethynyl groups and also with no substituents. Without exception, all these non-rigid luminophores showed negative-sign CPL signals in the UV-visible region, suggesting temporal generation of energetically non-equivalent non-mirror image structures as far-from equilibrium open-flow systems at the S1 state. For comparison, unsubstituted naphthalene, anthracene, tetracene and pyrene, which are achiral, rigid, planar luminophores, did not obviously show CPL/CD signals. However, camphor, which is a rigid chiral luminophore, showed mirror-image CPL/CD signals. The dissymmetry ratio of CPL (glum) for the oligofluorenes increased discontinuously, ranging from ≈ −(0.2 to 2.0) × 10−3, when the viscosity of the liquids increased. When the fluorene ring number increased, the glum value extrapolated at [η] = 0 reached −0.8 × 10−3 at 420 nm, leading to (–)-CPL signals predicted in the vacuum state. Our comprehensive CPL and CD study should provide a possible answer to the molecular parity violation hypothesis arising due to the weak neutral current mediated by the Z0-boson.

scholarly journals Modulation of circularly polarized luminescence through excited-state symmetry breaking and interbranched exciton coupling in helical push–pull organic systems

2020 ◽  
Vol 11 (2) ◽  
pp. 567-576 ◽  
Author(s):  
Kais Dhbaibi ◽  
Ludovic Favereau ◽  
Monika Srebro-Hooper ◽  
Cassandre Quinton ◽  
Nicolas Vanthuyne ◽  
...  
Keyword(s):  
Excited State ◽  
Symmetry Breaking ◽  
Luminescence Intensity ◽  
Solvent Polarity ◽  
Circularly Polarized ◽  
Polarity Effect ◽  
Exciton Coupling ◽  
Organic Systems ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

Solvent polarity effect on circularly polarized luminescence intensity was assessed in helical push–pull organic systems through excited-state symmetry breaking and interbranched exciton coupling.

Excited-state chiral discrimination observed by time-resolved circularly polarized luminescence measurements

1989 ◽  
Vol 111 (8) ◽  
pp. 3082-3083 ◽  
Author(s):  
David H. Metcalf ◽  
Seth W. Snyder ◽  
Shuguang Wu ◽  
Gary L. Hilmes ◽  
James P. Riehl ◽  
...  
Keyword(s):  
Excited State ◽  
Chiral Discrimination ◽  
Time Resolved ◽  
Circularly Polarized ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

scholarly journals Aggregation-Induced Symmetry Breaking from Achiral Systems

2020 ◽  
Author(s):  
Haoke Zhang ◽  
Ryan Tsz Kin Kwok ◽  
Jacky W. Y. Lam ◽  
Ben Zhong Tang
Keyword(s):  
Symmetry Breaking ◽  
Chiral Molecule ◽  
Aggregate State ◽  
Interesting Phenomenon ◽  
Circularly Polarized ◽  
Water Fraction ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
The Origin Of Life ◽  
The Difference

Debates on the source of chirality have lasted for several centuries due to its significance for the exploration of the origin of life. It is still a thorny scientific problem that how the first chiral molecule is generated without any chiral factors. In this work, an interesting phenomenon, aggregation-induced symmetry breaking (AISB), is observed in achiral diphenylethylene and <i>p</i>-terphenyl derivatives. For compound (<i>E</i>)-1,2-Bis(2,4,5-trimethylphenyl)ethene (2,4,5-TMe-DPE), there is no chiroptical signal both in its solution and crystal state. However, unexpected chiroptical signals, circular dichroism (CD) and circularly polarized luminescence (CPL), are observed in their aggregate state and the emission dissymmetry factor is as high as 0.015 at 70% water fraction. Meantime, time-dependent CD and CPL effect are also investigated which suggests that AISB involves both dynamic and kinetic processes. Calculation is further carried out to prove the existence of two enantiomers in diphenylethylene and <i>p</i>-terphenyl derivatives. Finally, we propose that the symmetry breaking in aggregate state might be caused by the difference of resolution rate to two enantiomers.

scholarly journals Aggregation-Induced Symmetry Breaking from Achiral Systems

2020 ◽  
Author(s):  
Haoke Zhang ◽  
Ryan Tsz Kin Kwok ◽  
Jacky W. Y. Lam ◽  
Ben Zhong Tang
Keyword(s):  
Symmetry Breaking ◽  
Chiral Molecule ◽  
Aggregate State ◽  
Interesting Phenomenon ◽  
Circularly Polarized ◽  
Water Fraction ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence ◽  
The Origin Of Life ◽  
The Difference

Debates on the source of chirality have lasted for several centuries due to its significance for the exploration of the origin of life. It is still a thorny scientific problem that how the first chiral molecule is generated without any chiral factors. In this work, an interesting phenomenon, aggregation-induced symmetry breaking (AISB), is observed in achiral diphenylethylene and <i>p</i>-terphenyl derivatives. For compound (<i>E</i>)-1,2-Bis(2,4,5-trimethylphenyl)ethene (2,4,5-TMe-DPE), there is no chiroptical signal both in its solution and crystal state. However, unexpected chiroptical signals, circular dichroism (CD) and circularly polarized luminescence (CPL), are observed in their aggregate state and the emission dissymmetry factor is as high as 0.015 at 70% water fraction. Meantime, time-dependent CD and CPL effect are also investigated which suggests that AISB involves both dynamic and kinetic processes. Calculation is further carried out to prove the existence of two enantiomers in diphenylethylene and <i>p</i>-terphenyl derivatives. Finally, we propose that the symmetry breaking in aggregate state might be caused by the difference of resolution rate to two enantiomers.

scholarly journals Spontaneous and directed symmetry breaking in the formation of chiral nanocrystals

2019 ◽  
Vol 116 (23) ◽  
pp. 11159-11164 ◽  
Author(s):  
Uri Hananel ◽  
Assaf Ben-Moshe ◽  
Haim Diamant ◽  
Gil Markovich
Keyword(s):  
Symmetry Breaking ◽  
Mirror Symmetry ◽  
Natural World ◽  
Colloidal Synthesis ◽  
Aqueous Environment ◽  
Chemical Systems ◽  
Chiral Amplification ◽  
Circularly Polarized Luminescence ◽  
Left And Right ◽  
Crucial Part

Symmetry plays a crucial part in our understanding of the natural world. Mirror symmetry breaking is of special interest as it is related to life as we know it. Studying systems which display chiral amplification, therefore, could further our understanding of symmetry breaking in chemical systems, in general, and thus also of the asymmetry in Nature. Here, we report on strong chiral amplification in the colloidal synthesis of intrinsically chiral lanthanide phosphate nanocrystals, measured via circularly polarized luminescence. The amplification involves spontaneous symmetry breaking into either left- or right-handed nanocrystals below a critical temperature. Furthermore, chiral tartaric acid molecules in the solution direct the amplified nanocrystal handedness through a discontinuous transition between left- and right-handed excess. We analyze the observations based on the statistical thermodynamics of critical phenomena. Our results demonstrate how chiral minerals with high enantiopurity can form in a racemic aqueous environment.

scholarly journals Time‐resolved circularly polarized luminescence of Eu 3+ ‐based systems

Chirality ◽  
2020 ◽  
Author(s):  
Uri Hananel ◽  
Gal Schwartz ◽  
Guy Paiss ◽  
Lorenzo Arrico ◽  
Francesco Zinna ◽  
...  
Keyword(s):  
Time Resolved ◽  
Circularly Polarized ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

scholarly journals Mirror symmetry breaking at the molecular level.

1996 ◽  
Vol 93 (21) ◽  
pp. 11435-11442 ◽  
Author(s):  
V. Avetisov ◽  
V. Goldanskii
Keyword(s):  
Symmetry Breaking ◽  
Mirror Symmetry ◽  
Molecular Level
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