scholarly journals Reactivity and selectivity modulation within a molecular assembly: recent examples from photochemistry

2021 ◽  
Author(s):  
Yeshua Sempere ◽  
Martin Morgenstern ◽  
Thorsten Bach ◽  
Manuel Plaza
Keyword(s):  
Organic Synthesis ◽  
Weak Interactions ◽  
Research Effort ◽  
Molecular Assembly ◽  
Photochemical Reactions ◽  
Host Molecule ◽  
Major Research ◽  
Molecular Assemblies ◽  
Unique Outcome

AbstractIn recent years, photochemical reactions have emerged as powerful transformations which significantly expand the repertoire of organic synthesis. However, a certain lack of selectivity can hamper their application and limit their scope. In this context, a major research effort continues to focus on an improved control over stereo- and chemoselectivity that can be achieved in molecular assemblies between photosubstrates and an appropriate host molecule. In this tutorial review, some recent, representative examples of photochemical reactions have been collected whose unique outcome is dictated by the formation of a molecular assembly driven by non-covalent weak interactions. Graphical Abstract

Molecular assembly of highly symmetric molecules under a hydrogen bond framework controlled by alkyl building blocks: a simple approach to fine-tune nanoscale structures

Soft Matter ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 486-491 ◽  
Author(s):  
Pimsai Tanphibal ◽  
Kohji Tashiro ◽  
Suwabun Chirachanchai
Keyword(s):  
Hydrogen Bond ◽  
Weak Interactions ◽  
Building Blocks ◽  
Molecular Assembly ◽  
Simple Approach ◽  
Molecular Assemblies ◽  
Nanoscale Structures ◽  
Fine Tune

This work shows how the molecular assemblies under the hydrogen bond and weak interactions fine-tune their morphologies through the systematic studies of highly symmetric molecules, i.e. diamine-based benzoxazine dimers.

LED Light Sources in Organic Synthesis: An Entry to A Novel Approach

2021 ◽  
Vol 18 ◽  
Author(s):  
Aparna Das
Keyword(s):  
Organic Compounds ◽  
Organic Synthesis ◽  
Photochemical Reaction ◽  
Low Cost ◽  
Environmentally Friendly ◽  
Photochemical Reactions ◽  
Light Sources ◽  
Blue Led ◽  
Oxidation Reduction ◽  
Novel Approach

: In recent years, photocatalytic technology has shown great potential as a low-cost, environmentally friendly, and sustainable technology. Compared to other light sources in photochemical reaction, LEDs have advantages in terms of efficiency, power, compatibility, and environmentally-friendly nature. This review highlights the most recent advances in LED-induced photochemical reactions. The effect of white and blue LEDs in reactions such as oxidation, reduction, cycloaddition, isomerization, and sensitization is discussed in detail. No other reviews have been published on the importance of white and blue LED sources in the photocatalysis of organic compounds. Considering all the facts, this review is highly significant and timely.

Physiological characteristics of high genetic merit and low genetic merit dairy cows: a comparison

1998 ◽  
Vol 1998 ◽  
pp. 4-4
Author(s):  
A. Sorensen ◽  
M. Alamer ◽  
C. H. Knight
Keyword(s):  
Dairy Cows ◽  
Research Effort ◽  
Genetic Selection ◽  
Plasma Samples ◽  
Major Research ◽  
Genetic Merit ◽  
Casting Technique ◽  
Biological Variables ◽  
Holstein Friesian ◽  
Key Enzyme

Genetic selection has greatly improved individual cow productivity. A high genetic merit Holstein Friesian cow will produce 10,000 of litres of milk in a 305 day lactation, those of lower genetic merit half this amount. Despite major research effort in generating these differences, quantitative biological description of what has been achieved is lacking. The aim of this study was to compare biological variables of relevance to milk synthesis in well defined high genetic merit and lower genetic merit dairy cows.12 cows of high genetic merit (HGM: top 5% of UK national herd) and 12 of lower genetic merit (LGM: close to UK average) were purchased from the Blythbank and Langhill herds; the ontogeny of these selection lines has been described elsewhere (Woolliams et al, 1993). Mean parity was 3.7±0.3 and was balanced between HGM and LGM. Management of the two groups was identical. Measurements were made over a period of two weeks close to peak lactation. Milk yield was recorded at each milking. Plasma samples were collected and analysed for a variety of hormones by radioimmunoassay and metabolites by established spectrophotometric assays. Udder size was determined by a casting technique (Dewhurst et al., 1993) and mammary biopsies for key enzyme activities were obtained as described by Knight et. al. (1992). Differences between lines were analysed by analysis of variance (ANOVA).

Dynamics of proton, ion, molecule, and crystal lattice in functional molecular assemblies

2021 ◽  
Author(s):  
Tomoyuki Akutagawa ◽  
Takashi Takeda ◽  
Norihisa Hoshino
Keyword(s):  
Crystal Lattice ◽  
Long Range ◽  
Molecular Assembly ◽  
Molecular Processes ◽  
Molecular Assemblies ◽  
Electrical Conducting ◽  
Molecular Rotations

Dynamic molecular processes, such as short- or long-range proton (H+) and ion (M+) motions, and molecular rotations in electrical conducting and magnetic molecular assembly enable to fabricate the electron –...

Physiological characteristics of high genetic merit and low genetic merit dairy cows: a comparison

1998 ◽  
Vol 1998 ◽  
pp. 4-4 ◽  
Author(s):  
A. Sorensen ◽  
M. Alamer ◽  
C. H. Knight
Keyword(s):  
Dairy Cows ◽  
Research Effort ◽  
Genetic Selection ◽  
Plasma Samples ◽  
Major Research ◽  
Genetic Merit ◽  
Casting Technique ◽  
Biological Variables ◽  
Holstein Friesian ◽  
Key Enzyme

Genetic selection has greatly improved individual cow productivity. A high genetic merit Holstein Friesian cow will produce 10,000 of litres of milk in a 305 day lactation, those of lower genetic merit half this amount. Despite major research effort in generating these differences, quantitative biological description of what has been achieved is lacking. The aim of this study was to compare biological variables of relevance to milk synthesis in well defined high genetic merit and lower genetic merit dairy cows.12 cows of high genetic merit (HGM: top 5% of UK national herd) and 12 of lower genetic merit (LGM: close to UK average) were purchased from the Blythbank and Langhill herds; the ontogeny of these selection lines has been described elsewhere (Woolliams et al, 1993). Mean parity was 3.7±0.3 and was balanced between HGM and LGM. Management of the two groups was identical. Measurements were made over a period of two weeks close to peak lactation. Milk yield was recorded at each milking. Plasma samples were collected and analysed for a variety of hormones by radioimmunoassay and metabolites by established spectrophotometric assays. Udder size was determined by a casting technique (Dewhurst et al., 1993) and mammary biopsies for key enzyme activities were obtained as described by Knight et. al. (1992). Differences between lines were analysed by analysis of variance (ANOVA).

MESOBIOTIC EMERGENCE: MOLECULAR AND ENSEMBLE COMPLEXITY IN EARLY EVOLUTION

2003 ◽  
Vol 06 (01) ◽  
pp. 15-35 ◽  
Author(s):  
BARAK SHENHAV ◽  
DANIEL SEGRÈ ◽  
DORON LANCET
Keyword(s):  
Origin Of Life ◽  
Organic Synthesis ◽  
Living Cell ◽  
Early Evolution ◽  
Molecular Assemblies ◽  
Complexity Level ◽  
Covalently Bonded ◽  
Multicellular Organisms

In addition to the visible complexity expressed in the morphogenesis of multicellular organisms, two levels of microscopic complexity may be discerned within every living cell. The first level is related to covalently bonded structures, namely molecules. The second level has to do with the generation of non-covalent molecular assemblies. Origin of life research has largely focused on the first complexity level, i.e. the appearance of covalent biopolymers. We present a life emergence scenario based mainly on the second complexity level. We argue that homeostatic molecular ensembles, for which we have coined the term "mesobiotic," have assumed a half-way position between prebiotic organic synthesis and full-fledged cellular (biotic) life.

scholarly journals Controlling Molecular Assembly and Charge Transport of N-Type Organic Semiconductors with Sterically Demanding Substituents

2020 ◽  
Author(s):  
Craig Yu ◽  
Naoya Kojima ◽  
Shohei Kumagai ◽  
Tadanori Kurosawa ◽  
Hiroyuki Ishii ◽  
...  
Keyword(s):  
Charge Transport ◽  
Organic Semiconductors ◽  
Field Effect Transistors ◽  
Molecular Assembly ◽  
Fine Tuning ◽  
Organic Field Effect Transistors ◽  
Molecular Assemblies ◽  
Design And Synthesis ◽  
Sterically Demanding ◽  
The Difference

Abstract Benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI) n-type organic semiconductors demonstrate unique multi-fold intermolecular hydrogen-bonding interactions that lead to excellent aggregated structures, charge transports, and electron mobility. However, the robust intermolecular anchoring of BQQDI presents challenges for further fine-tuning molecular assemblies and organic semiconductor properties. Herein, we report the design and synthesis of two BQQDI derivatives with sterically demanding phenyl- and cyclohexyl-substituted BQQDI (Ph–BQQDI and Cy6–BQQDI), where the two organic semiconductors show distinct molecular assemblies and degrees of intermolecular orbital overlaps. In addition, the difference in their packing motifs led to strikingly different band structures that give rise to contrasting charge-transport capabilities. As a result, Cy6–BQQDI shows excellent transistor performances in both single-crystalline and polycrystalline thin-film organic field-effect transistors.

scholarly journals West Nile virus in Europe: understanding the present to gauge the future

2010 ◽  
Vol 15 (10) ◽  
Author(s):  
P Reiter
Keyword(s):  
New York ◽  
West Nile Virus ◽  
Natural History ◽  
Research Effort ◽  
Western Hemisphere ◽  
Current Understanding ◽  
Major Research ◽  
West Nile ◽  
Old World ◽  
History Of

The appearance of West Nile virus in New York in 1999 and the unprecedented panzootic that followed, have stimulated a major research effort in the western hemisphere and a new interest in the presence of this virus in the Old World. This review considers current understanding of the natural history of this pathogen, with particular regard to transmission in Europe.

Structural consequences of weak interactions in dispirooxindole derivatives

2015 ◽  
Vol 71 (11) ◽  
pp. 1001-1009
Author(s):  
Krishnan Ravikumar ◽  
Balasubramanian Sridhar ◽  
Jagadeesh Babu Nanubolu ◽  
Govindaraju Karthik ◽  
Basi Venkata Subba Reddy
Keyword(s):  
Weak Interactions ◽  
Noncovalent Interactions ◽  
Building Blocks ◽  
Cascade Reactions ◽  
Structural Features ◽  
Molecular Assembly ◽  
Diastereoselective Synthesis ◽  
Structural Variations ◽  
Racemic Mixtures

Spiro scaffolds are being increasingly utilized in drug discovery due to their inherent three-dimensionality and structural variations, resulting in new synthetic routes to introduce spiro building blocks into more pharmaceutically active molecules. Multicomponent cascade reactions, involving thein situgeneration of carbonyl ylides from α-diazocarbonyl compounds and aldehydes, and 1,3-dipolar cycloadditon with 3-arylideneoxindoles gave a novel class of dispirooxindole derivatives, namely 1,1′′-dibenzyl-5′-(4-chlorophenyl)-4′-phenyl-4′,5′-dihydrodispiro[indoline-3,2′-furan-3′,3′′-indoline]-2,2′′-dione, C44H33ClN2O3, (I), 1′′-acetyl-1-benzyl-5′-(4-chlorophenyl)-4′-phenyl-4′,5′-dihydrodispiro[indoline-3,2′-furan-3′,3′′-indoline]-2,2′′-dione, C39H29ClN2O4, (II), 1′′-acetyl-1-benzyl-4′,5′-diphenyl-4′,5′-dihydrodispiro[indoline-3,2′-furan-3′,3′′-indoline]-2,2′′-dione, C39H30N2O4, (III), and 1′′-acetyl-1-benzyl-4′,5′-diphenyl-4′,5′-dihydrodispiro[indoline-3,2′-furan-3′,3′′-indoline]-2,2′′-dione acetonitrile hemisolvate, C39H30N2O4·0.5C2H3N, (IV). All four compounds exist as racemic mixtures of theSSSRandRRRSstereoisomers. In these structures, the two H atoms of the dihydrofuran ring and the two substituted oxindole rings are in atransorientation, facilitating intramolecular C—H...O and π–π interactions. These weak interactions play a prominent role in the structural stability and aid the highly regio- and diastereoselective synthesis. In each of the four structures, the molecular assembly in the crystal is also governed by weak noncovalent interactions. Compound (IV) is the solvated analogue of (III) and the two compounds show similar structural features.

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