Unveiling how intramolecular stacking modes of covalently linked dimers dictate photoswitching properties

AbstractCovalently linked π-stacked dimers represent the most significant platform for elucidating the relationship between molecular alignments and their properties. Here, we present the one-pot synthesis of two intramolecularly π-stacked dimers and disclose how intramolecular stacking modes dictate photoswitching properties. The dimer, which features cofacially stacked chromophores and geometrically favours intramolecular photochemical [2 + 2] cycloadditions, displays a nearly irreversible photoswitching behaviour. By contrast, the dimer, bearing crosswise stacked chromophores, is geometrically unfavourable for the cycloaddition and exhibits a highly reversible photoswitching process, in which the homolysis and reformation of carbon−carbon single bonds are involved. Moreover, the chiral carbon centres of both dimers endow these photoswitches with chirality and the separated enantiomers exhibit tuneable chiroptical properties by photoswitching. This work reveals that intramolecular stacking modes significantly influence the photochemical properties of π-stacked dimers and offers a design strategy toward chiral photoswitchable materials.

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A Photoredox-Catalyzed Four Component Reaction for the Atom-Efficient Synthesis of Complex Secondary Amines

10.26434/chemrxiv.11811927.v1 ◽

2020 ◽

Author(s):

Lisa Marie Kammer ◽

Matthias Krumb ◽

Benjamin Spitzbarth ◽

Benjamin Lipp ◽

Jonas Kühlborn ◽

...

Keyword(s):

Secondary Amines ◽

Efficient Synthesis ◽

One Pot ◽

Simultaneous Formation ◽

Mild Conditions ◽

Simple Protocol ◽

Reaction Proceeds ◽

Styrene Derivatives ◽

The One ◽

Single Bonds

The one-pot sulfonylation/aminoalkylation of styrene derivatives furnishing highly substituted gamma-sulfonylamines was accomplished through a photoredox-catalyzed four-component reaction. Apart from one molecule of water and the sodium counterion of the sulfinate, all atoms of the starting materials are transferred to the final product, rendering this process highly atom-efficient. The operationally simple protocol allows for the simultaneous formation of three new single bonds (C–S, C–N, and C–C) and therefore grants rapid access to structurally diverse products. The reaction proceeds under mild conditions in aqueous acetonitrile and shows a broad scope, including natural products and drug-like molecules.

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A Photoredox-Catalyzed Four Component Reaction for the Atom-Efficient Synthesis of Complex Secondary Amines

10.26434/chemrxiv.11811927 ◽

2020 ◽

Author(s):

Lisa Marie Kammer ◽

Matthias Krumb ◽

Benjamin Spitzbarth ◽

Benjamin Lipp ◽

Jonas Kühlborn ◽

...

Keyword(s):

Secondary Amines ◽

Efficient Synthesis ◽

One Pot ◽

Simultaneous Formation ◽

Mild Conditions ◽

Simple Protocol ◽

Reaction Proceeds ◽

Styrene Derivatives ◽

The One ◽

Single Bonds

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Misreading Egypt

10.3366/edinburgh/9781474424776.003.0002 ◽

2018 ◽

Author(s):

Jesse Schotter

Keyword(s):

New Media ◽

Narrative Form ◽

Experimental Film ◽

Tower Of Babel ◽

Avant Garde ◽

Sergei Eisenstein ◽

History Of ◽

The One ◽

The Relationship ◽

Modern Technologies

The first chapter of Hieroglyphic Modernisms exposes the complex history of Western misconceptions of Egyptian writing from antiquity to the present. Hieroglyphs bridge the gap between modern technologies and the ancient past, looking forward to the rise of new media and backward to the dispersal of languages in the mythical moment of the Tower of Babel. The contradictory ways in which hieroglyphs were interpreted in the West come to shape the differing ways that modernist writers and filmmakers understood the relationship between writing, film, and other new media. On the one hand, poets like Ezra Pound and film theorists like Vachel Lindsay and Sergei Eisenstein use the visual languages of China and of Egypt as a more primal or direct alternative to written words. But Freud, Proust, and the later Eisenstein conversely emphasize the phonetic qualities of Egyptian writing, its similarity to alphabetical scripts. The chapter concludes by arguing that even avant-garde invocations of hieroglyphics depend on narrative form through an examination of Hollis Frampton’s experimental film Zorns Lemma.

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Researching (with) Major Food Retailers

Gastronomica The Journal of Food and Culture ◽

10.1525/gfc.2015.15.3.33 ◽

2015 ◽

Vol 15 (3) ◽

pp. 33-39 ◽

Cited By ~ 3

Author(s):

David Evans

Keyword(s):

Food Systems ◽

Academic Research ◽

Social Scientists ◽

Major Food ◽

Food Retailers ◽

Food Retailer ◽

The One ◽

The Uk ◽

The Relationship ◽

Opening Up

This paper considers the relationship between social science and the food industry, and it suggests that collaboration can be intellectually productive and morally rewarding. It explores the middle ground that exists between paid consultancy models of collaboration on the one hand and a principled stance of nonengagement on the other. Drawing on recent experiences of researching with a major food retailer in the UK, I discuss the ways in which collaborating with retailers can open up opportunities for accessing data that might not otherwise be available to social scientists. Additionally, I put forward the argument that researchers with an interest in the sustainability—ecological or otherwise—of food systems, especially those of a critical persuasion, ought to be empirically engaging with food businesses. I suggest that this is important in terms of generating better understandings of the objectionable arrangements that they seek to critique, and in terms of opening up conduits through which to affect positive changes. Cutting across these points is the claim that while resistance to commercial engagement might be misguided, it is nevertheless important to acknowledge the power-geometries of collaboration and to find ways of leveling and/or leveraging them. To conclude, I suggest that universities have an important institutional role to play in defining the terms of engagement as well as maintaining the boundaries between scholarship and consultancy—a line that can otherwise become quite fuzzy when the worlds of commerce and academic research collide.

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A Series of Metal-Organic Frameworks for Selective CO2 Capture and Catalytic Oxidative Carboxylation of Olefins

10.26434/chemrxiv.7068509 ◽

2018 ◽

Author(s):

Huong T. D. Nguyen ◽

Y B. N. Tran ◽

Hung N. Nguyen ◽

Tranh C. Nguyen ◽

Felipe Gándara ◽

...

Keyword(s):

Room Temperature ◽

Gas Adsorption ◽

New Materials ◽

One Pot ◽

Acid Gas ◽

Naphthalene Diimide ◽

Styrene Carbonate ◽

Metal Organic ◽

Adsorption Of Co ◽

The One

Three novel lanthanide metal˗organic frameworks (Ln-MOFs), namely MOF-590, -591, and -592 were constructed from a naphthalene diimide tetracarboxylic acid. Gas adsorption measurements of MOF-591 and -592 revealed good adsorption of CO2 (low pressure, at room temperature) and moderate CO2 selectivity over N2 and CH4. Accordingly, breakthrough measurements were performed on a representative MOF-592, in which the separation of CO2 from binary mixture containing N2 and CO2 was demonstrated without any loss in performance over three consecutive cycles. Moreover, MOF-590, MOF-591, and MOF-592 exhibited catalytic activity in the one-pot synthesis of styrene carbonate from styrene and CO2 under mild conditions (1 atm CO2, 80 °C, and solvent-free). Among the new materials, MOF-590 revealed a remarkable efficiency with exceptional conversion (96%), selectivity (95%), and yield (91%).

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Choice Of Technique And The Volume Of Saving (A Re-Examination Of The Cobb-Douglas Model)

The Pakistan Development Review ◽

10.30541/v8i4pp.606-617 ◽

1968 ◽

Vol 8 (4) ◽

pp. 606-617

Author(s):

Mohammad Anisur Rahman

Keyword(s):

Economic Development ◽

Production Function ◽

Development Policy ◽

Social Goals ◽

The Other ◽

Economic Development Policy ◽

Labour Intensity ◽

The One ◽

Choice Of Technique ◽

The Relationship

The purpose of this paper is to re-examine the relationship between the degree of aggregate labour-intensity and the aggregate volume of saving in an economy where a Cobb-6ouglas production function in its traditional form can be assumed to give a good approximation to reality. The relationship in ques¬tion has an obviously important bearing on economic development policy in the area of choice of labour intensity. To the extent that and in the range where an increase in labour intensity would adversely affect the volume of savings, a con¬flict arises between two important social objectives, i.e., higher rate of capital formation on the one hand and greater employment and distributive equity on the other. If relative resource endowments in the economy are such that such a "competitive" range of labour-intensity falls within the nation's attainable range of choice, development planners will have to arrive at a compromise between these two social goals.

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A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

Current Organic Chemistry ◽

10.2174/1385272824666200226114306 ◽

2020 ◽

Vol 24 (4) ◽

pp. 465-471 ◽

Cited By ~ 2

Author(s):

Zita Rádai ◽

Réka Szabó ◽

Áron Szigetvári ◽

Nóra Zsuzsa Kiss ◽

Zoltán Mucsi ◽

...

Keyword(s):

Quantum Chemical ◽

Room Temperature ◽

Phase Transfer ◽

One Pot ◽

Substrate Dependence ◽

Triethylbenzylammonium Chloride ◽

One Step ◽

The Pudovik Reaction ◽

The One ◽

Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

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An Overview of the One-pot Synthesis of Imidazolines

Current Organic Chemistry ◽

10.2174/1385272824999201001153735 ◽

2020 ◽

Vol 24 (20) ◽

pp. 2341-2355

Author(s):

Thaipparambil Aneeja ◽

Sankaran Radhika ◽

Mohan Neetha ◽

Gopinathan Anilkumar

Keyword(s):

Asymmetric Catalysis ◽

Organic Compounds ◽

Ring Opening ◽

Ecological Impact ◽

Chiral Auxiliary ◽

One Pot ◽

One Pot Synthesis ◽

The One ◽

Synthetic Intermediate ◽

Heterocyclic Moiety

One-pot syntheses are a simple, efficient and easy methodology, which are widely used for the synthesis of organic compounds. Imidazoline is a valuable heterocyclic moiety used as a synthetic intermediate, chiral auxiliary, chiral catalyst and a ligand for asymmetric catalysis. Imidazole is a fundamental unit of biomolecules that can be easily prepared from imidazolines. The one-pot method is an impressive approach to synthesize organic compounds as it minimizes the reaction time, separation procedures, and ecological impact. Many significant one-pot methods such as N-bromosuccinimide mediated reaction, ring-opening of tetrahydrofuran, triflic anhydrate mediated reaction, etc. were reported for imidazoline synthesis. This review describes an overview of the one-pot synthesis of imidazolines and covers literature up to 2020.

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Synthesis and Kinetics of Highly Substituted Piperidines in the Presence of Tartaric Acid as a Catalyst

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207321666180228115130 ◽

2018 ◽

Vol 21 (4) ◽

pp. 302-311

Author(s):

Younes Ghalandarzehi ◽

Mehdi Shahraki ◽

Sayyed M. Habibi-Khorassani

Keyword(s):

Ambient Temperature ◽

Tartaric Acid ◽

Aromatic Aldehydes ◽

One Pot ◽

Rate Determining Step ◽

State Approximation ◽

Solvent Free Conditions ◽

Steady State Approximation ◽

Absorbance Changes ◽

The One

Aim & Scope: The synthesis of highly substituted piperidine from the one-pot reaction between aromatic aldehydes, anilines and β-ketoesters in the presence of tartaric acid as a catalyst has been investigated in both methanol and ethanol media at ambient temperature. Different conditions of temperature and solvent were employed for calculating the thermodynamic parameters and obtaining an experimental approach to the kinetics and mechanism. Experiments were carried out under different temperature and solvent conditions. Material and Methods: Products were characterized by comparison of physical data with authentic samples and spectroscopic data (IR and NMR). Rate constants are presented as an average of several kinetic runs (at least 6-10) and are reproducible within ± 3%. The overall rate of reaction is followed by monitoring the absorbance changes of the products versus time on a Varian (Model Cary Bio- 300) UV-vis spectrophotometer with a 10 mm light-path cell. Results: The best result was achieved in the presence of 0.075 g (0.1 M) of catalyst and 5 mL methanol at ambient temperature. When the reaction was carried out under solvent-free conditions, the product was obtained in a moderate yield (25%). Methanol was optimized as a desirable solvent in the synthesis of piperidine, nevertheless, ethanol in a kinetic investigation had none effect on the enhancement of the reaction rate than methanol. Based on the spectral data, the overall order of the reaction followed the second order kinetics. The results showed that the first step of the reaction mechanism is a rate determining step. Conclusion: The use of tartaric acid has many advantages such as mild reaction conditions, simple and readily available precursors and inexpensive catalyst. The proposed mechanism was confirmed by experimental results and a steady state approximation.

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