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.

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

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.

Four-fold click reactions: Generation of tetrahedral methane- and adamantane-based building blocks for higher-order molecular assemblies

2009 ◽  
Vol 7 (22) ◽  
pp. 4734 ◽  
Author(s):  
Oliver Plietzsch ◽  
Christine Inge Schilling ◽  
Mariyan Tolev ◽  
Martin Nieger ◽  
Clemens Richert ◽  
...  
Keyword(s):  
Building Blocks ◽  
Higher Order ◽  
Molecular Assemblies ◽  
Click Reactions

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 –...

Ligand-directed assembly engineering of trapezoidal {Ti5} building blocks stabilized by dimethylglyoxime

2019 ◽  
Vol 48 (27) ◽  
pp. 9916-9919 ◽  
Author(s):  
Qing-Rong Ding ◽  
Gui-Lan Xu ◽  
Lei Zhang ◽  
Jian Zhang
Keyword(s):  
Directed Assembly ◽  
Building Blocks ◽  
Molecular Assembly

A facile approach of ligand-directed assembly of trapezoidal {Ti5} building blocks was successfully established, which gave rise to interesting hybrid clusters including the first molecular assembly of porphyrin photosensitizer and titanium-oxo cluster.

Synthesis of Sterically Congested Carbamates of Carbohydrates through Organic Base Catalysis

Synthesis ◽  
2019 ◽  
Vol 51 (15) ◽  
pp. 2897-2908 ◽  
Author(s):  
Anji Chen ◽  
Dan Wang ◽  
Lalith P. Samankumara ◽  
Guijun Wang
Keyword(s):  
Hydroxy Group ◽  
Current Method ◽  
Building Blocks ◽  
Base Catalysis ◽  
Organic Base ◽  
Molecular Assemblies ◽  
Effective Catalyst ◽  
Organic Bases ◽  
Derivatives Of ◽  
General Method

4,6-O-Benzylidene acetal protected α-methoxy d-glucose and d-glucosamine are useful building blocks for the syntheses of carbohydrate derivatives and functional molecular assemblies. In this research, we have developed a general method for the preparation of C-3 carbamate derivatives of densely functionalized glucose and glucosamine with isocyanates using organic bases as catalysts. Without a suitable catalyst, the C-3 hydroxy group of the glucosamine derivative could not be converted into the corresponding carbamates when treated with isocyanates. Several organic bases were screened as the catalysts for the reactions, and we discovered that 5.0 mol% of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was an effective catalyst for the carbamoylation reaction. A library of both alkyl and aryl carbamate derivatives of the two sterically congested carbohydrates have been effectively synthesized using the current method.

Relevance of the Entropy Factor in Stereoselectivity Control of Asymmetric Photoreactions

Synlett ◽  
2020 ◽  
Vol 31 (13) ◽  
pp. 1259-1267
Author(s):  
Tadashi Mori
Keyword(s):  
Activation Energy ◽  
Excited States ◽  
Weak Interactions ◽  
Supramolecular Interactions ◽  
Thermal Reactions ◽  
Thermodynamics And Kinetics ◽  
Control Concept ◽  
Entropy Factor ◽  
Fine Tune

Entropy as well as enthalpy factors play substantial roles in various chemical phenomena such as equilibrium and reactions. However, the entropy factors are frequently underestimated in most instances, particularly in synthetic chemistry. In reality, the entropy factor can be in competition with the enthalpy factor or can even be decisive in determining the overall free or activation energy change upon molecular interaction and chemical transformation, particularly where weak interactions in ground and/or excited states are significant. In this account, we overview the importance of the entropy factor in various chemical phenomena in both thermodynamics and kinetics and in the ground and excited states. It is immediately apparent that many diastereo- and enantioselective photoreactions are entropy-controlled. Recent advances on the entropy-control concept in asymmetric photoreactions are further discussed. Understanding the entropy-control concept will pave the way to improve, fine-tune, and even invert the chemo- and stereoselectivity of relevant chemical phenomena.1 Introduction2 Role of Entropy in Supramolecular Interactions3 Selected Examples of Entropy-Driven Thermal Reactions4 Classical Examples of Entropy Control in Photoreactions5 Entropy-Driven Asymmetric Photoreactions6 Advances in Entropy Control7 Perspective

Molecular assembly at surfaces: progress and challenges

2017 ◽  
Vol 204 ◽  
pp. 9-33 ◽  
Author(s):  
R. Raval
Keyword(s):  
Building Blocks ◽  
Covalent Bonding ◽  
Molecular Assembly ◽  
Theoretical Modelling ◽  
Top Down ◽  
Molecular Systems ◽  
Natural Systems ◽  
Surfaces And Interfaces ◽  
Macromolecular Systems ◽  
Determine System

Molecules provide versatile building blocks, with a vast palette of functionalities and an ability to assemble via supramolecular and covalent bonding to generate remarkably diverse macromolecular systems. This is abundantly displayed by natural systems that have evolved on Earth, which exploit both supramolecular and covalent protocols to create the machinery of life. Importantly, these molecular assemblies deliver functions that are reproducible, adaptable, finessed and responsive. There is now a real need to translate complex molecular systems to surfaces and interfaces in order to engineer 21st century nanotechnology. ‘Top-down’ and ‘bottom-up’ approaches, and utilisation of supramolecular and covalent assembly, are currently being used to create a range of molecular architectures and functionalities at surfaces. In parallel, advanced tools developed for interrogating surfaces and interfaces have been deployed to capture the complexities of molecular behaviour at interfaces from the nanoscale to the macroscale, while advances in theoretical modelling are delivering insights into the balance of interactions that determine system behaviour. A few examples are provided here that outline molecular behaviour at surfaces, and the level of complexity that is inherent in such systems.

scholarly journals Towards computer-guided tuning of the crystal packing of porous organic cages

2014 ◽  
Vol 70 (a1) ◽  
pp. C667-C667
Author(s):  
Angeles Pulido ◽  
Ming Liu ◽  
Paul Reiss ◽  
Anna Slater ◽  
Sam Chong ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Engineering ◽  
Molecular Sieves ◽  
Structure Prediction ◽  
Crystal Packing ◽  
Aromatic Aldehydes ◽  
Lattice Energy ◽  
Building Blocks ◽  
Molecular Assembly ◽  
Computational Techniques

Among microporous materials, there has been an increasing recent interest in porous organic cage (POC) crystals, which can display permanent intrinsic (molecular) and extrinsic (crystal network) porosity. These materials can be used as molecular sieves for gas separation and potential applications as enzyme mimics have been suggested since they exhibit structural response toward guest molecules[1]. Small structural modifications of the initial building blocks of the porous organic molecules can lead to quite different molecular assembly[1]. Moreover, the crystal packing of POCs is based on weak molecular interactions and is less predictable that other porous materials such as MOFs or zeolites.[2] In this contribution, we show that computational techniques -molecular conformational searches and crystal structure prediction- can be successfully used to understand POC crystal packing preferences. Computational results will be presented for a series of closely related tetrahedral imine- and amine-linked porous molecules, formed by [4+6] condensation of aromatic aldehydes and cyclohexyl linked diamines. While the basic cage is known to have one strongly preferred crystal structure, the presence of small alkyl groups on the POC modifies its crystal packing preferences, leading to extensive polymorphism. Calculations were able to successfully identify these trends as well as to predict the structures obtained experimentally, demonstrating the potential for computational pre-screening in the design of POCs within targeted crystal structures. Moreover, the need of accurate molecular (ab initio calculations) and crystal (based on atom-atom potential lattice energy minimization) modelling for computer-guided crystal engineering will be discussed.

“Chemistry-on-the-complex”: functional RuIIpolypyridyl-type sensitizers as divergent building blocks

2018 ◽  
Vol 47 (20) ◽  
pp. 7577-7627 ◽  
Author(s):  
Tina Mede ◽  
Michael Jäger ◽  
Ulrich S. Schubert
Keyword(s):  
Solar Cells ◽  
Energy Conversion ◽  
Dye Sensitized Solar Cells ◽  
Building Blocks ◽  
Molecular Assemblies ◽  
Ruthenium Polypyridyl ◽  
Dye Sensitized ◽  
Biomedical Diagnosis ◽  
Sensitized Solar Cells

Ruthenium polypyridyl type complexes are potent photoactive compounds, and have found – among others – a broad range of important applications in the fields of biomedical diagnosis and phototherapy, energy conversion schemes such as dye-sensitized solar cells (DSSCs) and molecular assemblies for tailored photo-initiated processes.

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