Relevance of the Entropy Factor in Stereoselectivity Control of Asymmetric Photoreactions

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

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Equifinality versus evolutionary fragility: the role of collective weak interactions

Proceedings of the 2000 Congress on Evolutionary Computation. CEC00 (Cat. No.00TH8512) ◽

10.1109/cec.2000.870820 ◽

2002 ◽

Cited By ~ 1

Author(s):

L.G. Volkert ◽

M. Conrad

Keyword(s):

Weak Interactions

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EpCAM promotes endosomal modulation of the cortical RhoA zone for epithelial organization

Nature Communications ◽

10.1038/s41467-021-22482-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Cécile Gaston ◽

Simon De Beco ◽

Bryant Doss ◽

Meng Pan ◽

Estelle Gauquelin ◽

...

Keyword(s):

Cell Shape ◽

Specific Protein ◽

Cell Polarization ◽

Stress Fiber ◽

Fiber Formation ◽

Endosomal Trafficking ◽

Transient Zone ◽

And Behavior ◽

Fine Tune

AbstractAt the basis of cell shape and behavior, the organization of actomyosin and its ability to generate forces are widely studied. However, the precise regulation of this contractile network in space and time is unclear. Here, we study the role of the epithelial-specific protein EpCAM, a contractility modulator, in cell shape and motility. We show that EpCAM is required for stress fiber generation and front-rear polarity acquisition at the single cell level. In fact, EpCAM participates in the remodeling of a transient zone of active RhoA at the cortex of spreading epithelial cells. EpCAM and RhoA route together through the Rab35/EHD1 fast recycling pathway. This endosomal pathway spatially organizes GTP-RhoA to fine tune the activity of actomyosin resulting in polarized cell shape and development of intracellular stiffness and traction forces. Impairment of GTP-RhoA endosomal trafficking either by silencing EpCAM or by expressing Rab35/EHD1 mutants prevents proper myosin-II activity, stress fiber formation and ultimately cell polarization. Collectively, this work shows that the coupling between co-trafficking of EpCAM and RhoA, and actomyosin rearrangement is pivotal for cell spreading, and advances our understanding of how biochemical and mechanical properties promote cell plasticity.

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The role of zero-field splitting and π-stacking interaction of different nitrogen-donor ligands on the optical properties of luminescent rhenium tricarbonyl complexes

New Journal of Chemistry ◽

10.1039/d1nj01544c ◽

2021 ◽

Author(s):

Plinio Cantero-López ◽

Yoan Hidalgo-Rosa ◽

Zoraida Sandoval-Olivares ◽

Julián Santoyo-Flores ◽

Pablo Mella ◽

...

Keyword(s):

Excited States ◽

Coordination Compounds ◽

Donor Ligands ◽

Zero Field ◽

Zero Field Splitting ◽

Nitrogen Donor Ligands ◽

Nitrogen Donor ◽

Π Stacking Interaction ◽

Rhenium Tricarbonyl

Rhenium tricarbonyl complexes are one of the most important classes of coordination compounds in inorganic chemistry. Exploring their luminescent excited states, lowest singlet (S1), and the lowest triplet (T1), is...

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A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

Crystals ◽

10.3390/cryst11010013 ◽

2020 ◽

Vol 11 (1) ◽

pp. 13

Author(s):

Mohd. Muddassir ◽

Abdullah Alarifi ◽

Mohd. Afzal

Keyword(s):

Density Functional ◽

Weak Interactions ◽

Energy Levels ◽

Hirshfeld Surface ◽

Binding Energies ◽

Orbital Energy ◽

Aminosalicylic Acid ◽

Full Characterization

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.

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Influence of TOPO and TOPO-CdSe/ZnS Quantum Dots on Luminescence Photodynamics of InP/InAsP/InPHeterostructure Nanowires

Nanomaterials ◽

10.3390/nano11030640 ◽

2021 ◽

Vol 11 (3) ◽

pp. 640

Author(s):

Artem I. Khrebtov ◽

Vladimir V. Danilov ◽

Anastasia S. Kulagina ◽

Rodion R. Reznik ◽

Ivan D. Skurlov ◽

...

Keyword(s):

Quantum Dots ◽

Excited States ◽

Molecular Beam ◽

Surface Passivation ◽

Low Energy ◽

Trioctylphosphine Oxide ◽

Reverse Transfer ◽

Semiconductor Heterostructure ◽

Ligand Type

The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A significant dependence of the photoluminescence (PL) dynamics of the InAsP insertions on the ligand type was shown, which was associated with the changes in the excitation translation channels in the heterostructure. This change was caused by a different interaction of the ligand shells with the surface of InP NWs, which led to the formation of different interfacial low-energy states at the NW-ligand boundary, such as surface-localized antibonding orbitals and hybridized states that were energetically close to the radiating state and participate in the transfer of excitation. It was shown that the quenching of excited states associated with the capture of excitation to interfacial low-energy traps was compensated by the increasing role of the “reverse transfer” mechanism. As a result, the effectiveness of TOPO-CdSe/ZnS QDs as a novel surface passivation coating was demonstrated.

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The Activating Effect of Strong Acid for Pd-Catalyzed Directed C–H Activation by Concerted Metalation-Deprotonation Mechanism

Molecules ◽

10.3390/molecules26134083 ◽

2021 ◽

Vol 26 (13) ◽

pp. 4083

Author(s):

Heming Jiang ◽

Tian-Yu Sun

Keyword(s):

Activation Energy ◽

Dft Calculations ◽

Energy Barrier ◽

Computational Study ◽

Strong Acid ◽

Activation Energy Barrier ◽

Pd Catalysts ◽

Acid Ligand ◽

Strong Acids

A computational study on the origin of the activating effect for Pd-catalyzed directed C–H activation by the concerted metalation-deprotonation (CMD) mechanism is conducted. DFT calculations indicate that strong acids can make Pd catalysts coordinate with directing groups (DGs) of the substrates more strongly and lower the C–H activation energy barrier. For the CMD mechanism, the electrophilicity of the Pd center and the basicity of the corresponding acid ligand for deprotonating the C–H bond are vital to the overall C–H activation energy barrier. Furthermore, this rule might disclose the role of some additives for C–H activation.

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Insights into the synergistic role of metal–lattice oxygen site pairs in four-centered C–H bond activation of methane: the case of CuO

Catalysis Science & Technology ◽

10.1039/c5cy01784j ◽

2016 ◽

Vol 6 (11) ◽

pp. 3984-3996 ◽

Cited By ~ 29

Author(s):

Jithin John Varghese ◽

Quang Thang Trinh ◽

Samir H. Mushrif

Keyword(s):

Activation Energy ◽

Copper Oxide ◽

Bond Activation ◽

Lattice Oxygen ◽

Oxide Surfaces ◽

Energy Barriers ◽

Metal Lattice ◽

Oxygen Site ◽

Site Pair

Of the three mechanisms for activation of methane on copper and copper oxide surfaces, the under-coordinated Cu–O site pair mediated mechanism on CuO surfaces has the lowest activation energy barriers.

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