Cyclic and noncyclic electron delocalization in cyclic .pi.-conjugated molecules. Relative delocalizabilities of donor-acceptor disposition isomers

1982 ◽  
Vol 21 (5) ◽  
pp. 1798-1805 ◽  
Author(s):  
Satoshi. Inagaki ◽  
Yoshio. Hirabayashi
Keyword(s):  
Electron Delocalization ◽  
Conjugated Molecules ◽  
Pi Conjugated ◽  
Donor Acceptor

scholarly journals Three-Dimensional Fully pi-Conjugated Macrocycles: When Truly 3D-Aromatic and when 2D-Aromatic-in-3D?

2021 ◽  
Author(s):  
Henrik Ottosson ◽  
Ouissam El Bakouri ◽  
Dariusz Szczepanik ◽  
Kjell Jorner ◽  
Rabia Ayub ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Electron Delocalization ◽  
Conjugated Molecules ◽  
Aromatic Molecules ◽  
Pi Conjugated ◽  
Aromatic Character ◽  
Conjugated Macrocycles ◽  
Polycyclic Aromatic ◽  
Symmetric Structures ◽  
Macrocyclic Molecules

Recently, several fully pi-conjugated macrocycles with strongly puckered or cage-type structures have been synthesized and found to exhibit aromatic character according to both experiments and computations. Herein, we examine their electronic structures and put them in relation to truly 3D-aromatic molecules (e.g., closo-boranes and certain charged fullerenes) as well as 2D-aromatic polycyclic aromatic hydrocarbons. We use qualitative theory combined with quantum chemical calculations, and find that the macrocycles explored thus far should be described as 2D-aromatic with three-dimensional structures (abbr. 2D-aromatic-in-3D) instead of truly 3D-aromatic. Besides fulfilling the 6n + 2 pi-electron rule, 3D-aromatic molecules with highly symmetric structures (e.g., Td and Oh) have a number of molecular orbital (MO) levels that are (at least) triply degenerate. At lower symmetries, the triple (or higher) orbital degeneracies should be kept in approximate sense. This last criterion is not fulfilled by macrocyclic cage molecules that are 2D-aromatic-in-3D. Their aromaticity results from a fulfillment of Hückel’s 4n + 2 rule for each individual macrocyclic path, yet, their pi-electron counts are coincidentally 6n + 2 numbers for macrocycles with three tethers of equal lengths. We instead link the 3D-macrocyclic molecules explored earlier to naphthalene, motivating their description as 2D-aromatics albeit with 3D structures. It is notable that macrocyclic cages which are 2D-aromatic-in-3D can be aromatic also when the tethers are of different lengths, i.e., when their pi-electron counts differ from 6n + 2. Finally, we identify tetrahedral and cubic pi-conjugated molecules that fulfill the 6n + 2 rule and which exhibit significant electron delocalization. Yet, their properties are similar to those of analogous compounds with electron counts that differ from 6n + 2. Thus, despite that these tetrahedral and cubic molecules show substantial pi-electron delocalization they should not be classified as true 3D-aromatics.

Well-defined star-shaped donor–acceptor conjugated molecules for organic resistive memory devices

2015 ◽  
Vol 51 (75) ◽  
pp. 14179-14182 ◽  
Author(s):  
Hung-Chin Wu ◽  
Jicheng Zhang ◽  
Zhishan Bo ◽  
Wen-Chang Chen
Keyword(s):  
Charge Storage ◽  
Memory Devices ◽  
Resistive Memory ◽  
Conjugated Molecules ◽  
Storage Materials ◽  
End Groups ◽  
Donor Acceptor ◽  
Solution Processable ◽  
First Time

Solution processable star-shaped donor–acceptor conjugated molecules are explored for the first time as charge storage materials for resistor-type memory devices with a triphenylamine (donor) core, and three 1.8-naphthalimide (acceptors) end-groups.

Computation of Electron Delocalization for Extended Cyclic Conjugated Molecules

2016 ◽  
Vol 69 (9) ◽  
pp. 999 ◽  
Author(s):  
Suhwan Song ◽  
Minwoo Han ◽  
Eunji Sim
Keyword(s):  
Structural Parameters ◽  
Quantitative Relationship ◽  
Structural Heterogeneity ◽  
Electron Delocalization ◽  
Strongly Correlated ◽  
Conjugated Molecules ◽  
Alkyl Groups ◽  
Out Of Plane ◽  
Two Parameters ◽  
Torsional Angles

Cyclic conjugated molecules have relatively planar conformations due to overlap of adjacent π-orbitals of delocalized electrons and which is strongly correlated with the degree of electron delocalization. We first demonstrate the quantitative relationship between structural heterogeneity and two structural parameters: out-of-plane distances of atoms and torsional angles between neighbouring aromatic moieties. The molecular characteristic-dependent trend of planarity is presented in terms of these two parameters for the number of unit moieties, type and distribution of linkers, and substituting alkyl groups. The method presented may provide a simple yet systematic guide for determining the degree of delocalization of cyclic conjugated molecules.

Fluorenone core donor–acceptor–donor π-conjugated molecules end-capped with dendritic oligo(thiophene)s: synthesis, liquid crystalline behaviour, and photovoltaic applications

2011 ◽  
Vol 21 (14) ◽  
pp. 5238 ◽  
Author(s):  
Frédéric Lincker ◽  
Benoît Heinrich ◽  
Rémi De Bettignies ◽  
Patrice Rannou ◽  
Jacques Pécaut ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Conjugated Molecules ◽  
Photovoltaic Applications ◽  
Donor Acceptor

scholarly journals Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

2016 ◽  
Vol 7 (12) ◽  
pp. 2234-2239 ◽  
Author(s):  
Manuel Souto ◽  
Vega Lloveras ◽  
Sergi Vela ◽  
Maria Fumanal ◽  
Imma Ratera ◽  
...  
Keyword(s):  
Magnetic Coupling ◽  
Electron Delocalization ◽  
Redox States ◽  
Donor Acceptor

scholarly journals Secondary Through-Space Interactions: Achieving Single-Molecule White-Light Emission from Clusteroluminogens with Isolated Phenyl Rings

2022 ◽  
Author(s):  
Jianyu Zhang ◽  
Parvej Alam ◽  
Siwei Zhang ◽  
Hanchen Shen ◽  
Lianrui Hu ◽  
...  
Keyword(s):  
Single Molecule ◽  
White Light ◽  
Light Emission ◽  
Photophysical Properties ◽  
White Light Emission ◽  
Excitation Wavelength ◽  
Conjugated Molecules ◽  
Long Wavelength ◽  
Phenyl Rings ◽  
Donor Acceptor

Clusteroluminogens (CLgens) refer to some non-conjugated molecules that show visible light due to the formation of aggregates and unique electronic properties with through-space interactions (TSI). Although mature and systematic theories of molecular photophysics have been developed to study conventional conjugated chromophores, it is still challenging to endow CLgens with designed photophysical properties by manipulating TSI. Herein, three CLgens with non-conjugated donor-acceptor structures and different halide substituents with secondary TSI are designed and synthesized. These molecules show multiple emissions and even white-light emission in the crystalline state and the intensity ratio of these multiple emission peaks is easily manipulated by changing the halide atom and excitation wavelength. Experimental and theoretical results successfully disclose the electronic nature of these multiple emissions: through-space conjugation for short-wavelength fluorescence, through-space charge transfer based on secondary TSI for long-wavelength fluorescence, and room-temperature phosphorescence. The introduction of secondary TSI to CLgens not only enriches their varieties of photophysical properties but also inspires the establishment of novel aggregate photophysics for clusteroluminescence.

Sign in / Sign up

Export Citation Format

Share Document