Molecular Coplanarity and Self-Assembly Promoted by Intramolecular Hydrogen Bonds

Zhu, Congzhi; Mu, Anthony U.; Lin, Yan‐Ru; Guo, Zihao; Yuan, Tianyu; Wheeler, Steven E.; Fang, Lei

doi:10.1021/acs.orglett.6b03225

Cited by 42 publications

(55 citation statements)

References 47 publications

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“…Planar conformation is of critical importance for organic semiconductors to enhance intramolecular charge transport and decrease bandgap because of close π–π stacking and high intermolecular orbital overlap in solid state . To achieve highly planar conformations, the intramolecular noncovalent interactions, such as hydrogen bonds, N…O, S…O, and F…S, can be served as “conformational lock” to limit the free rotation of aromatic rings, which is a widely used approach to designing organic thin film transistor (OTFT) and organic photovoltaics (OPV) materials . However, the planar π‐conjugated molecules are always resulting fluorescence quenched in the solid state due to the tightly π–π stacking.…”

Section: Methodsmentioning

confidence: 99%

Aggregation‐Induced Emission of Highly Planar Enaminone Derivatives: Unexpected Fluorescence Enhancement by Bromine Substitution

Shu

Liu

et al. 2019

Advanced Optical Materials

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F…S, can be served as "conformational lock" to limit the free rotation of aromatic rings, which is a widely used approach to designing organic thin film transistor (OTFT) and organic photo voltaics (OPV) materials. [17][18][19] However, the planar π-conjugated molecules are always resulting fluorescence quenched in the solid state due to the tightly π-π stacking. For better application in the field of luminescence, it is urgently need to develop planar organic π-conjugated molecules with AIE-active. [20,21] For example, Yang et al. introduced S…O or Se…O noncovalent intramolecular interactions into ACQ molecules, which stabilized planar structure and restricted the photoisomerization in solid state, resulting in interesting AIE effects. [20] Halogen bonding as noncovalent interaction has been widely adopted in supramolecular chemistry for self-assembly of liquid crystals, magnetic and conducting materials and biological systems, whereas drew relatively less attention in the design of organic solid fluorescent materials. [22][23][24][25] In recent years, the incorporation of heavy bromide atom has been utilized extensively for the construction of pure organic materials with roomtemperature phosphorescence. [26][27][28] The well-known heavy atom effect of bromide can promote both singlet-to-triplet and triplet-to-singlet intersystem crossing by enhanced spin-orbit coupling. [29,30] Furthermore, the rigidification effect of halogen bonding in solid states will suppress nonradiative relaxation of triplets, and thus strengthen the phosphorescent emission. [31,32] For example, Bolton et al. revealed the importance of intermolecular short contact halogen bonding (CO⋅⋅⋅BrAr) on the bright phosphorescence from crystals or cocrystals of 2,5-dihexyloxy-4-bromobenzaldehyde and its analogs. [33] Shi et al. also demonstrated that the formation of multiple Br⋅⋅⋅Br halogen bonding in solid states could enhance phosphorescence quantum yields for a series of dibromobenzene derivatives. [34] At the same time, the heavy-atom effect always leads to significant fluorescent quenching of bromine-substituted organic fluorophores compared with their hydrogen analogs. [35,36] However, tunable multicolor solid-state fluorescence has been observed in organic cocrystals with the supramolecular arrangements governed by halogen bonding. [37] In another example, several metal-organic cages equipped with halogen bonding interactions exhibited brighter solid state emission than their organic fluorescent ligands. [38] Therefore, halogen bonding may also have a great potential for the construction of organic solid fluorescent materials.Unlike typical aggregation-induced-emission (AIE) molecules with twist/rotor structures, two AIE-active enaminone derivatives with highly planar conformations are herein reported. Interestingly, the bromine-substituted enaminone fluorophore (BrE) exhibits unexpected stronger emission in solid states than unsubstituted enaminone fluorophore (HE), which is seldom observed for organic fluorophores. Remarkably, the fluo...

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Section: Methodsmentioning

confidence: 99%

Aggregation‐Induced Emission of Highly Planar Enaminone Derivatives: Unexpected Fluorescence Enhancement by Bromine Substitution

Shu

Liu

et al. 2019

Advanced Optical Materials

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“…By using the diethyl derivative as an acetylene component in the Sonogashira reaction, researchers synthesized model compounds for studying the molecular and supramolecular properties of this series of analogs. This was accomplished by looking at the intramolecular hydrogen bonds of the individual molecules [8] (Figure 2). As shown above, the Pd-catalyzed reaction was conducted at 80 °C and resulted in a yield of 79% of the diacetylene derivative.…”

Section: Synthesis Of Acetylenequinonesmentioning

confidence: 99%

Fundamental and Applied Aspects of the Chemistry of Acetylenylquinones

Vasilevsky¹,

Stepanov²

2020

REFFIT

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In addition to the reported synthetic routes for the acetylene derivatives of quinones, a detailed analysis of the fundamental chemical, physicochemical, and biological properties of this class of compounds is presented herein. The advantages of Pd- and Cu-catalyzed cross-coupling of terminal alkynes with iodarenes via the Sonogashira reaction to produce new acetylenylquinones with predetermined properties are examined. Here, combining quinoid and acetylene residues into one molecule gives the resulting compounds chemical specificity, as demonstrated by several reported examples of non-trivial transformations. In particular, the presence of the quinoid cycle significantly increases the electrophilicity of the triple bond and determines the range of transformation possibilities. Moreover, acetylenylquinones have heightened sensitivity to both external (such as the reaction temperature and the nature of the solvent) and internal (e.g., the structure of substituents in the nucleus and the acetylene fragment) factors. For example, regioselective cleavage of a strong triple bond under the action of amines is possible in the absence of a metal catalyst. Peri-substituted acetylenyl-9,10-anthraquinones are most suited for the synthetic route because of the proximity of the acetylene and carbonyl groups. Mechanisms of reactions of selective alkynylquinones are described.

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“…At 333 K, the aromatic proton H a of 2a was remarkably upfield shifted by 193 ppb on increasing the concentration from 0.1378 to 4.411mm (Figure S17i nt he Supporting Information), which suggested an aggregationp rocess. The self-association constant of 2a was determined to be 316 m À1 by an isodesmic aggregation model( Figure S18 in the Supporting Information) at 333 K. [59] Compounds 2b and 2c also showed clear aggregation with self-association constants of 15 and 57 m À1 at 298 K, respectively (Figure S19-S22 in the Supporting Information). In contrast, 2d and 3a-3d did not exhibit obvious changes of chemicals hifts in the aromatic region at various concentrations at 298 K( Figure S23-S27 in the SupportingI nformation), probablyb ecause the bulky groups in the 6-, 14-, and2 2-positions of triindolo-truxene prohibit molecular aggregation.…”

Section: Molecular Assemblymentioning

confidence: 99%

Triindolo‐Truxene Derivatives: Design, Synthesis, and Fine‐Tuning of Electronic Properties and Molecular Assembly through Molecular Engineering

Chen

Zhou

et al. 2018

Chemistry A European J

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Triindolo-truxene, a C 3 -symmetric moleculew ith a large p-conjugated plane, hass ix methylene carbon atoms and three aromatic carbon atoms that can be facilely functionalized. Herein, butyl, carbonyl, cyano, and/or malononitrile groups were introduced at six methylene carbon atoms (6-, 14-, 22-or 8-, 16-, 24-positions) and/or three aromatic carbon atoms (2-, 10-, and1 8-positions)o ft riindolo-truxene to produce eight derivatives. Their photophysical properties, electrochemical properties,a nd molecular assembly can be effectively modulated by substituents and substitution patterns. Incorporation of electron-deficient groups led to redshifts in both the absorption and emissiono ft hesed erivatives and also lowered their HOMO and LUMO levels.D iffer-ent substitution patterns resulted in the differentintramolecular donor-acceptor interactions. Electron-deficient substituents at the methylene carbon atoms in the 6-, 14-, and 22positions led to intramolecular charget ransfer from the fluorene arms to the truxenec ore, whereas the corresponding substitutions at the methylene carbon atoms in the 8-, 16-, and 24-positions resulted in intramolecular charget ransfer from the truxene core to the fluorene arms. The molecular packingi ns ingle crystals and molecular aggregationi ns olution are also influenced by the substituents and substitution patterns.T hisw ork provides as traightforwards trategy to alter the properties of triindolo-truxene.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.Figure 4. Photographs of triindolo-truxene derivatives in CH 2 Cl 2 (1 10 À5 m) under sunlight (top) and under3 65 nm UV light (bottom).Figure 5. Cyclic voltammograms of a) 2a-2d and b) 3a-3d in CH 2 Cl 2 .

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Molecular Coplanarity and Self-Assembly Promoted by Intramolecular Hydrogen Bonds

Cited by 42 publications

References 47 publications

Aggregation‐Induced Emission of Highly Planar Enaminone Derivatives: Unexpected Fluorescence Enhancement by Bromine Substitution

Aggregation‐Induced Emission of Highly Planar Enaminone Derivatives: Unexpected Fluorescence Enhancement by Bromine Substitution

Fundamental and Applied Aspects of the Chemistry of Acetylenylquinones

Triindolo‐Truxene Derivatives: Design, Synthesis, and Fine‐Tuning of Electronic Properties and Molecular Assembly through Molecular Engineering

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