scholarly journals Global Aromaticity at the Nanoscale

2019 ◽  
Author(s):  
Michel Rickhaus ◽  
Michael Jirasek ◽  
Lara Tejerina ◽  
Henrik Gotfredsen ◽  
Martin D. Peeks ◽  
...  
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Oxidation State ◽  
Single Molecule ◽  
Ring Current ◽  
Electronic Devices ◽  
Three Dimensional ◽  
Average Oxidation State ◽  
Ring Currents ◽  
Cyclic Molecule

<div><p>Aromaticity is an important concept for predicting electronic delocalisation in molecules, particularly for designing organic semiconductors and single-molecule electronic devices. It is most simply defined by the ability of a cyclic molecule to sustain a ring current when placed in a magnetic field. Hückel’s rule states that if a ring has [4n+2] π-electrons, it will be aromatic with an induced magnetisation that opposes the external field inside the ring, whereas if it has 4n π-electrons, it will be antiaromatic with the opposite magnetisation. This rule reliably predicts the behaviour of small molecules, typically with circuits of less than about 22 π-electrons (n = 5). It is not clear whether aromaticity has a size limit and whether Hückel’s rule is valid in much larger macrocycles. Here, we present evidence for global aromaticity in a wide variety of porphyrin nanorings, with circuits of up to 162 π-electrons (n = 40; diameter 5 nm). We show that aromaticity can be controlled by changing the molecular structure, oxidation state and three-dimensional conformation. Whenever a global ring current is observed, its direction is correctly predicted by Hückel’s rule. The magnitude of the current is maximised when the average oxidation state of the porphyrin units is around 0.5–0.7, when the system starts to resemble a conductor with a partially filled valence band. Our results show that aromaticity can arise in large macrocycles, bridging the size gap between ring currents in molecular and mesoscopic rings.</p></div>

scholarly journals Global Aromaticity at the Nanoscale

2019 ◽  
Author(s):  
Michel Rickhaus ◽  
Michael Jirasek ◽  
Lara Tejerina ◽  
Henrik Gotfredsen ◽  
Martin D. Peeks ◽  
...  
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Oxidation State ◽  
Single Molecule ◽  
Ring Current ◽  
Electronic Devices ◽  
Three Dimensional ◽  
Average Oxidation State ◽  
Ring Currents ◽  
Cyclic Molecule

<div><p>Aromaticity is an important concept for predicting electronic delocalisation in molecules, particularly for designing organic semiconductors and single-molecule electronic devices. It is most simply defined by the ability of a cyclic molecule to sustain a ring current when placed in a magnetic field. Hückel’s rule states that if a ring has [4n+2] π-electrons, it will be aromatic with an induced magnetisation that opposes the external field inside the ring, whereas if it has 4n π-electrons, it will be antiaromatic with the opposite magnetisation. This rule reliably predicts the behaviour of small molecules, typically with circuits of less than about 22 π-electrons (n = 5). It is not clear whether aromaticity has a size limit and whether Hückel’s rule is valid in much larger macrocycles. Here, we present evidence for global aromaticity in a wide variety of porphyrin nanorings, with circuits of up to 162 π-electrons (n = 40; diameter 5 nm). We show that aromaticity can be controlled by changing the molecular structure, oxidation state and three-dimensional conformation. Whenever a global ring current is observed, its direction is correctly predicted by Hückel’s rule. The magnitude of the current is maximised when the average oxidation state of the porphyrin units is around 0.5–0.7, when the system starts to resemble a conductor with a partially filled valence band. Our results show that aromaticity can arise in large macrocycles, bridging the size gap between ring currents in molecular and mesoscopic rings.</p></div>

scholarly journals Global Aromaticity at the Nanoscale

2019 ◽  
Author(s):  
Michel Rickhaus ◽  
Michael Jirasek ◽  
Lara Tejerina ◽  
Henrik Gotfredsen ◽  
Martin D. Peeks ◽  
...  
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Oxidation State ◽  
Single Molecule ◽  
Ring Current ◽  
Electronic Devices ◽  
Three Dimensional ◽  
Average Oxidation State ◽  
Ring Currents ◽  
Cyclic Molecule

<div><p>Aromaticity is an important concept for predicting electronic delocalisation in molecules, particularly for designing organic semiconductors and single-molecule electronic devices. It is most simply defined by the ability of a cyclic molecule to sustain a ring current when placed in a magnetic field. Hückel’s rule states that if a ring has [4n+2] π-electrons, it will be aromatic with an induced magnetisation that opposes the external field inside the ring, whereas if it has 4n π-electrons, it will be antiaromatic with the opposite magnetisation. This rule reliably predicts the behaviour of small molecules, typically with circuits of less than about 22 π-electrons (n = 5). It is not clear whether aromaticity has a size limit and whether Hückel’s rule is valid in much larger macrocycles. Here, we present evidence for global aromaticity in a wide variety of porphyrin nanorings, with circuits of up to 162 π-electrons (n = 40; diameter 5 nm). We show that aromaticity can be controlled by changing the molecular structure, oxidation state and three-dimensional conformation. Whenever a global ring current is observed, its direction is correctly predicted by Hückel’s rule. The magnitude of the current is maximised when the average oxidation state of the porphyrin units is around 0.5–0.7, when the system starts to resemble a conductor with a partially filled valence band. Our results show that aromaticity can arise in large macrocycles, bridging the size gap between ring currents in molecular and mesoscopic rings.</p></div>

The Synthesis, Condensation, and Luminescence of Stilbenoid Oligomers with Alkoxysilane End Groups

2001 ◽  
Vol 665 ◽  
Author(s):  
H. Detert ◽  
E. Sugiono
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Three Dimensional ◽  
Synthetic Route ◽  
Heck Reactions ◽  
Transparent Films ◽  
Cross Metathesis ◽  
Fluorescent Materials ◽  
End Groups ◽  
Hydrolysis Of

ABSTRACTA synthetic route to highly luminescent organic semiconductors with curable alkoxysilyl groups is described. Monodisperse oligo(phenylenevinylene)s are rigidly connected to di- and triethoxysilanes via Heck reactions or via cross-metathesis. Hydrolysis of the silicic esters yields silanols condensing to linear and cyclic oligo-OPV-siloxanes or to three-dimensional networks, thus allowing the transformation of small molecules to fluorescent materials with well-defined chromophores. Transparent films are obtained by casting of soluble cyclosiloxanes and from OPV-silanetriols, the latter can be cured to insoluble networks.

scholarly journals Diketopyrrolopyrrole based organic semiconductors with different numbers of thiophene units: symmetry tuning effect on electronic devices

2018 ◽  
Vol 42 (6) ◽  
pp. 4017-4028 ◽  
Author(s):  
Qian Liu ◽  
Abhijith Surendran ◽  
Krishna Feron ◽  
Sergei Manzhos ◽  
Xuechen Jiao ◽  
...  
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Electronic Devices

Three new DPP small molecules were synthesized and used them in OFET devices.

Connecting Curable Siloxanes to Luminescent Organic Semiconductors - Monomers for Functional Hybrid Materials

2006 ◽  
Vol 939 ◽  
Author(s):  
Heiner Detert ◽  
Erli Sugiono
Keyword(s):  
Small Molecules ◽  
Organic Semiconductors ◽  
Hybrid Materials ◽  
Three Dimensional ◽  
End Groups ◽  
Rigid Connection ◽  
Hydrolysis Of

ABSTRACTLuminescent stilbenoid chromophores with two alkoxysilane end groups are prepared via hydrosilylation or condensation / reduction of substituted 5-ring OPVs with hydro- and aminopropylsilanes. Chromophore and curable units are connected via flexible spacers. To obtain compounds with a rigid connection between silane and π-system, iodo- or bromo-OPVs were coupled to alkoxysilanes carrying vinyl- or p-vinylphenyl moieties under Heck conditions. This approach allowed a combined connection of the chromophore to the silane moiety with an extension of the π-system. Hydrolysis of the alkoxysilanes yields silanols condensing to curable three-dimensional networks, thus allowing the transformation of small molecules to transparent and fluorescent films with well-defined chromophores.

scholarly journals Monte Carlo simulations of crystalline organic semiconductors

2013 ◽  
Vol 10 (1) ◽  
pp. 125-134
Author(s):  
Marko Mladenovic ◽  
Igor Stankovic
Keyword(s):  
Molecular Structure ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Small Molecules ◽  
Organic Semiconductors ◽  
Molecular Model ◽  
Three Dimensional

Molecular model for crystalline organic semiconductors based on small molecules is implemented in three-dimensional Monte Carlo simulations. In this paper results for naphthalene are presented. Molecular structure is considered in two configurations: within a single monocrystal and in vicinity of interface between two monocrystals with different crystalline orientations.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

scholarly journals Functionalization Strategies of PEDOT and PEDOT:PSS Films for Organic Bioelectronics Applications

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 212
Author(s):  
Gonzalo E. Fenoy ◽  
Omar Azzaroni ◽  
Wolfgang Knoll ◽  
Waldemar A. Marmisollé
Keyword(s):  
Small Molecules ◽  
Conducting Polymer ◽  
Organic Semiconductors ◽  
Synthesis Method ◽  
Polymer Synthesis ◽  
Preparation Methods ◽  
Electrophysiological Signals ◽  
Organic Bioelectronics ◽  
Biological Interfaces ◽  
Living Organisms

Organic bioelectronics involves the connection of organic semiconductors with living organisms, organs, tissues, cells, membranes, proteins, and even small molecules. In recent years, this field has received great interest due to the development of all kinds of devices architectures, enabling the detection of several relevant biomarkers, the stimulation and sensing of cells and tissues, and the recording of electrophysiological signals, among others. In this review, we discuss recent functionalization approaches for PEDOT and PEDOT:PSS films with the aim of integrating biomolecules for the fabrication of bioelectronics platforms. As the choice of the strategy is determined by the conducting polymer synthesis method, initially PEDOT and PEDOT:PSS films preparation methods are presented. Later, a wide variety of PEDOT functionalization approaches are discussed, together with bioconjugation techniques to develop efficient organic-biological interfaces. Finally, and by making use of these approaches, the fabrication of different platforms towards organic bioelectronics devices is reviewed.

scholarly journals Infrared nanospectroscopy reveals the molecular interaction fingerprint of an aggregation inhibitor with single Aβ42 oligomers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Simone Ruggeri ◽  
Johnny Habchi ◽  
Sean Chia ◽  
Robert I. Horne ◽  
Michele Vendruscolo ◽  
...  
Keyword(s):  
Small Molecules ◽  
Single Molecule ◽  
Protein Misfolding ◽  
Molecular Mechanisms ◽  
Chemical Sensitivity ◽  
Incomplete Knowledge ◽  
Parkinson’S Diseases ◽  
Aggregation Inhibitor ◽  
Misfolding Diseases

AbstractSignificant efforts have been devoted in the last twenty years to developing compounds that can interfere with the aggregation pathways of proteins related to misfolding disorders, including Alzheimer’s and Parkinson’s diseases. However, no disease-modifying drug has become available for clinical use to date for these conditions. One of the main reasons for this failure is the incomplete knowledge of the molecular mechanisms underlying the process by which small molecules interact with protein aggregates and interfere with their aggregation pathways. Here, we leverage the single molecule morphological and chemical sensitivity of infrared nanospectroscopy to provide the first direct measurement of the structure and interaction between single Aβ42 oligomeric and fibrillar species and an aggregation inhibitor, bexarotene, which is able to prevent Aβ42 aggregation in vitro and reverses its neurotoxicity in cell and animal models of Alzheimer’s disease. Our results demonstrate that the carboxyl group of this compound interacts with Aβ42 aggregates through a single hydrogen bond. These results establish infrared nanospectroscopy as a powerful tool in structure-based drug discovery for protein misfolding diseases.

Coherent Ring Currents in Chiral Aromatic Molecules Induced by Linearly Polarized UV Laser Pulses

2013 ◽  
Vol 543 ◽  
pp. 381-384 ◽  
Author(s):  
Manabu Kanno ◽  
Hirohiko Koho ◽  
Hirobumi Mineo ◽  
Sheng Hsien Lin ◽  
Yuichi Fujimura
Keyword(s):  
Aromatic Ring ◽  
Quantum Dynamics ◽  
Ring Current ◽  
Molecular System ◽  
Laser Pulses ◽  
Uv Laser ◽  
Aromatic Molecules ◽  
Ring Currents ◽  
Linearly Polarized ◽  
Coherent Ring

In recent years, laser control of electrons in molecular system and condensed matter has attracted considerable attention with rapid progress in laser science and technology [. In particular, control of π-electron rotation in photo-induced chiral aromatic molecules has potential utility to the next-generation ultrafast switching devices. In this paper, we present a fundamental principle of generation of ultrafast coherent ring currents and the control in photo-induced aromatic molecules. This is based on quantum dynamics simulations of π-electron rotations and preparation of unidirectional angular momentum by ultrashort UV laser pulses properly designed. For this purpose, we adopt 2,5-dichloro [(3,6) pyrazinophane (DCPH) fixed on a surface, which is a real chiral aromatic molecule with plane chirality. Here π electrons can be rotated along the aromatic ring clockwise or counterclockwise by irradiation of a linearly polarized laser pulse with the properly designed photon polarization direction and the coherent ring current with the definite direction along the aromatic ring is prepared. This is contrast to ordinary ring current in an achiral aromatic ring molecule with degenerate electronic excited state, which is prepared by a circularly polarized laser [2]. In this case, π electrons rotate along the Z-axis of the laboratory coordinates, while for the present case electrons rotate along the z-axis in molecular Cartesian coordinates. It should be noted that signals originated from the coherent ring currents prepared by linearly polarized ultrashort UV lasers are specific to the chiral molecule of interest.

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