2,600 results match your criteria demonstrated intermolecular

The role of propeptide-mediated autoinhibition and intermolecular chaperone in the maturation of cognate catalytic domain in leucine aminopeptidase.

J Struct Biol 2021 May 11:107741. Epub 2021 May 11.

School of Biological Science, Whiteknights Campus, University of Reading, RG6 6AS, UK. Electronic address:

Leucyl aminopeptidase A from Aspergillus oryzae RIB40 (AO-LapA) is an exo-acting peptidase, widely utilised in food debittering applications. AO-LapA is secreted as a zymogen by the host and requires enzymatic cleavage of the autoinhibitory propeptide to reveal its full activity. Scarcity of structural data of zymogen aminopeptidases hampers a better understanding of the details of their molecular action of autoinhibition and how this might be utilised to improve the properties of such enzymes by recombinant methods for more effective bioprocessing. Read More

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Copper-Catalyzed Direct sp C-H Silylation of Arylamides Using Disilanes.

Org Lett 2021 May 13. Epub 2021 May 13.

Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4-Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India.

A copper-catalyzed method for direct intermolecular -silylation of benzamides has been developed that affords organosilane products in moderate to high yields. The key features include: (i) use of commercially available disilanes as a silicon source with 8-aminoquinoline as a bidentate directing group, (ii) use of earth-abundant first-row transition metal, (iii) operationally simple conditions without the need of an inert atmosphere, and (iv) tolerance of a wide range of functional groups. The practicality and effectiveness of this method have been demonstrated by a gram-scale experiment. Read More

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Biradicaloid Behavior of a Twisted Double Bond.

J Phys Chem Lett 2021 May 13:4729-4734. Epub 2021 May 13.

Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.

A compound with a highly twisted C═C bond in the intermediate bond dissociation region was isolated, and its biradicaloid nature was experimentally demonstrated. A bianthrone derivative substituted with long-chain alkoxy groups was synthesized, and its twisted conformer was assembled into crystals through hydrophobic intermolecular interactions of the introduced alkoxy chains. X-ray crystallography revealed that the C═C bond connecting the two anthrone rings has a long bond length (1. Read More

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Precise Identification of the Dimethyl Sulfoxide Triggered Tricarbonyldichlororuthenium(II) Dimer for Releasing CO.

J Phys Chem Lett 2021 May 12:4658-4665. Epub 2021 May 12.

Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

Low concentrations of carbon monoxide (CO) can play vital roles in pharmacological and physiological functions in the human body. The transition-metal carbonyl complexes of the tricarbonyldichlororuthenium(II) dimer [Ru(CO)Cl (CORM-2)] were proposed as CO-releasing molecules (CORMs) to improve the delivery efficiency of CO for therapeutic effects. The accurate identification of final products for CORMs in solution and the detailed mechanisms of the release of CO were the essential prerequisite for its effective physiological application, which have been deficient. Read More

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Assessment of Anti-inflammatory-like, Antioxidant activities and Molecular docking of three Alkynyl-substituted 3-ylidenedihydrobenzo[d] isothiazole 1,1-dioxide derivatives.

Chem Biol Interact 2021 May 8:109513. Epub 2021 May 8.

Center for Oxygen, Research and Development (CORD) and Center for Interdisciplinary Research on Medicine (CIRM) Institute of Chemistry University of Liège, Sart-Tilman (B.6a), 4000 Liège, Belgium.

The presence of enyne and benzoisothiazole functions in the molecular architecture of compounds 1, 2 and 3 were expected to provide biochemical activities. In the present work, we first examined the molecular surface contact of three alkynyl-substituted 3-ylidenedihydrobenzo[d] isothiazole 1,1-dioxides. The analysis of the Hirshfeld surfaces reveals that only compound 3 exhibited a well-defined red spots, indicating intermolecular interactions identified as S-O···H, C-H···O and C-O···H contacts. Read More

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Photoinduced Oxidative Alkoxycarbonylation of Alkenes with Alkyl Formates.

Org Lett 2021 May 11. Epub 2021 May 11.

College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.

A photoinduced oxidative alkoxycarbonylation of alkenes initiated by intermolecular addition of alkoxycarbonyl radicals has been demonstrated. Employing alkyl formates as alkoxycarbonyl radical sources, a range of α,β-unsaturated esters were obtained with good regioselectivity and selectivity under ambient conditions. Read More

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Enzyme-Induced Supramolecular Order in Pyrene Dipeptide Hydrogels for the Development of an Efficient Energy-Transfer Template.

Biomacromolecules 2021 May 11. Epub 2021 May 11.

Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab 160062, India.

Peptide self-assembly is gathering much attention due to the precise control it provides for the arrangement of functional moieties for the fabrication of advanced functional materials. It is desirable to use a physical, chemical, or biological trigger that can control the self-assembly process. In the current article, we have applied an enzyme to induce the peptide self-assembly of an aromatic peptide amphiphile, which modulates the supramolecular order in the final gel phase material. Read More

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Solvent Effects in Supramolecular Chemistry: Linear Free Energy Relationships for Common Intermolecular Interactions.

Frank Würthner

J Org Chem 2021 May 11. Epub 2021 May 11.

Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany.

The proper choice of solvent is of major importance for all studies in supramolecular chemistry, including molecular recognition in host-guest systems, intramolecular folding, self-assembly, and supramolecular polymerization. In this Perspective, the usefulness of linear free energy relationships (LFERs) is highlighted to unravel the effect of solvents on coordinate bonding (e.g. Read More

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Structural basis of UDP-N-acetylglucosamine pyrophosphorylase and identification of promising terpenes to control Aedes aegypti.

Colloids Surf B Biointerfaces 2021 May 4;204:111820. Epub 2021 May 4.

Key Laboratory of Ministry of Education for Medicinal Plant Resource and Natural Pharmaceutical Chemistry, Shaanxi Normal University, Xi'an, China; School of Life Sciences, Shaanxi Normal University, Xi'an, China. Electronic address:

According to the world health organization (WHO) 2020 report, vector borne diseases account for 17 % of all infections with reported 700 thousand death each year. They are of considerable importance to health professionals as they are posing a serious health threat and include dengue fever, Zika fever, chikungunya, yellow fever, and other disease agents. Aedes aegypti serve as a vector for transmitting several of these tropical fevers. Read More

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Selective Construction of Trefoil knots and a Molecular Borromean Ring Induced by Steric Hindrance of Thioether Ligands.

Chem Asian J 2021 May 6. Epub 2021 May 6.

Fudan University, Department of Chemistry, CHINA.

Two Cp*-Rh III based trefoil knots were obtained in high yield under ambient conditions via the coordination-driven self-assembly of semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene ( L 1 ), ligand chloranilic acid (H 2 - CA ) and 6,11-dihydroxytetracene-5,12-dione (H 2 - TtDo ) with Cp*Rh III metal corner units, respectively. Furthermore, using the bulkier 4,4'-{[(2,5-dimethyl-1,4-phenylene)bis(methylene)]bis(sulfanediyl)}dipyridine ( L 2 ) in the place of ligand L 1 in the construction process resulted in the formation of a teranuclear metallacycle and a template-free Borromean ring in high yields thanks to significantly altered intermolecular forces between the constituent ligands induced by the sterically-hindering methyl groups of L 2 , as demonstrated via a detailed X-ray crystallographic analysis and NMR spectroscopy. Read More

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Revealing Differential Interaction Forces during Nanopore DNA Sequencing.

J Phys Chem B 2021 May 6. Epub 2021 May 6.

Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

The interaction between DNA and the nanopore structure plays an important role in nanopore DNA sequencing. Differential interaction forces between each base type and the nanopore structure are obtained by examining the correlation between translocation dwell time and the sequence. The viscous drag force and the intermolecular interaction are identified with single-nucleotide resolution. Read More

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Supramolecular structures of Ni and Cu with the sterically demanding Schiff base dyes driven by cooperative action of preagostic and other non-covalent interactions.

IUCrJ 2021 May 1;8(Pt 3):351-361. Epub 2021 May 1.

University of Tyumen, Volodarskogo Street 6, Tyumen, 625003, Russian Federation.

This work reports on synthesis and extensive experimental and theoretical investigations on photophysical, structural and thermal properties of the Ni and Cu discrete mononuclear homoleptic complexes [Ni()] and [Cu()] fabricated from the Schiff base dyes -HOCH-CH=N--CH (H) and -HOCH-CH=N--CH (H), containing the sterically crowding cyclo-hexyl units. The six-membered metallocycles adopt a clearly defined envelope conformation in [Ni()], while they are much more planar in the structures of [Ni()] and [Cu()]. It has been demonstrated by in-depth bonding analyses based on the ETS-NOCV and Interacting Quantum Atoms energy-decomposition schemes that application of the bulky substituents, containing several C-H groups, has led to the formation of a set of classical and unintuitive intra- and inter-molecular interactions. Read More

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Highly chemoselective synthesis of hindered amides via cobalt-catalyzed intermolecular oxidative hydroamidation.

Nat Commun 2021 05 5;12(1):2552. Epub 2021 May 5.

Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.

α-Tertiary amides are of great importance for medicinal chemistry. However, they are often challenging to access through conventional methods due to reactivity and chemoselectivity issues. Here, we report a single-step approach towards such amides via cobalt-catalyzed intermolecular oxidative hydroamidation of unactivated alkenes, using nitriles of either solvent- or reagent-quantities. Read More

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Fabrication and Thermo-Electro and Mechanical Properties Evaluation of Helical Multiwall Carbon Nanotube-Carbon Fiber/Epoxy Composite Laminates.

Polymers (Basel) 2021 Apr 29;13(9). Epub 2021 Apr 29.

Center of Advanced Materials, Faculty of Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia.

The development of advanced composite materials has taken center stage because of its advantages over traditional materials. Recently, carbon-based advanced additives have shown promising results in the development of advanced polymer composites. The inter- and intra-laminar fracture toughness in modes I and II, along with the thermal and electrical conductivities, were investigated. Read More

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Electrochemical Dehydrogenative C(sp )-H Amination.

Chemistry 2021 May 1. Epub 2021 May 1.

Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Otto-Hahn-Straße 11, 44227, Dortmund, Germany.

A transition-metal-free direct electrolytic C-H amination involving an electrochemically generated nitrenium ion intermediate has been developed. The electrosynthesis takes place in the absence of any organoiodine catalysts and is enabled by an in situ generated electrolyte. A novel, efficient intramolecular and intermolecular C-H amination has been demonstrated using a simple reaction setup. Read More

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Cluster Identification Using Modularity Optimization to Uncover Chemical Heterogeneity in Complex Solutions.

J Phys Chem A 2021 May 30;125(18):3986-3993. Epub 2021 Apr 30.

Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.

Structural heterogeneity is commonly manifested in solutions and liquids that feature competition of different interparticle forces. Identifying and characterizing heterogeneity across different length scales requires multimodal experimental measurement and/or the application of new techniques for the interrogation of atomistic simulation data. Within the latter, the parsing of networks of interparticle interactions (chemical networks) has been demonstrated to be a valuable tool for identifying subensembles of chemical environments. Read More

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Thixotropic Hydrogels Composed of Self-Assembled Nanofibers of Double-Hydrophobic Elastin-Like Block Polypeptides.

Int J Mol Sci 2021 Apr 15;22(8). Epub 2021 Apr 15.

Department of Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.

Physically crosslinked hydrogels with thixotropic properties attract considerable attention in the biomedical research field because their self-healing nature is useful in cell encapsulation, as injectable gels, and as bioinks for three-dimensional (3D) bioprinting. Here, we report the formation of thixotropic hydrogels containing nanofibers of double-hydrophobic elastin-like polypeptides (ELPs). The hydrogels are obtained with the double-hydrophobic ELPs at 0. Read More

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Antimicrobial Peptide Brevinin-1RL1 from Frog Skin Secretion Induces Apoptosis and Necrosis of Tumor Cells.

Molecules 2021 Apr 3;26(7). Epub 2021 Apr 3.

State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.

Cancer has always been one of the most common malignant diseases in the world. Therefore, there is an urgent need to find potent agents with selective antitumor activity against cancer cells. It has been reported that antimicrobial peptides (AMPs) can selectively target tumor cells. Read More

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Interstellar Enolization-Acetaldehyde (CH3CHO) and Vinyl Alcohol (H2CCH(OH)) as a Case Study.

Chemphyschem 2021 Apr 28. Epub 2021 Apr 28.

University of Hawaii at Manoa, 2545 McCarthy Mall, 96822, Honolulu, UNITED STATES.

Owing to the unique conditions in cold molecular clouds, enols-the thermody-namically less stable tautomers of aldehydes and ketones-do not undergo tautomerization to their more stable tautomers in the gas phase because they cannot overcome tautomerization barriers at the low temperatures. Laboratory studies of interstellar analog ices have demonstrated the formation of several keto-enol tautomer pairs in astrochemically relevant ice mixtures over the last years. However, so far only one of them, acetaldehyde-vinyl alcohol, has been detected in deep space. Read More

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Challenges in the synthesis of corannulene-based non-planar nanographenes on Au(111) surfaces.

Phys Chem Chem Phys 2021 May;23(18):10845-10851

Donostia International Physics Center, San Sebastián, 20018, Spain. and Centro de Fisica de Materiales, CSIC-UPV/EHU, San Sebastián, 20018, Spain and Ikerbasque, Basque Foundation for Science, Bilbao, 48013, Spain.

The on-surface synthesis of non-planar nanographenes is a challenging task. Herein, with the aid of bond-resolving scanning tunneling microscopy (BRSTM) and density functional theory (DFT) calculations, we present a systematic study aiming at the fabrication of corannulene-based nanographenes via intramolecular cyclodehydrogenation on a Au(111) surface. The formation of non-planar targeted products is confirmed to be energetically unfavorable compared to the formation of planar/quasi-planar undesired competing monomer products. Read More

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Quantum states of the endohedral fullerene Li@C surrounded by anions: energy decomposition analysis of nuclear wave functions.

Phys Chem Chem Phys 2021 Apr;23(16):9785-9803

Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, Yamagata 990-8560, Japan.

Lithium is the lightest metal element. To date, little is known about its quantized nuclear motion in nanoscale porous structures. Endohedral fullerene Li+@C60 is an ideal porous system for studying such a quantized motion. Read More

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Pinpointing cysteine oxidation sites by high-resolution proteomics reveals a mechanism of redox-dependent inhibition of human STING.

Sci Signal 2021 Apr 27;14(680). Epub 2021 Apr 27.

CRCHUM-Centre Hospitalier de l'Université de Montréal, 900 rue Saint Denis, Montréal, H2X 0A9 Québec, Canada.

Protein function is regulated by posttranslational modifications (PTMs), among which reversible oxidation of cysteine residues has emerged as a key regulatory mechanism of cellular responses. Given the redox regulation of virus-host interactions, the identification of oxidized cysteine sites in cells is essential to understand the underlying mechanisms involved. Here, we present a proteome-wide identification of reversibly oxidized cysteine sites in oxidant-treated cells using a maleimide-based bioswitch method coupled to mass spectrometry analysis. Read More

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Photosensitizer-driven nanoassemblies of homodimeric prodrug for self-enhancing activation and synergistic chemo-photodynamic therapy.

Theranostics 2021 7;11(12):6019-6032. Epub 2021 Apr 7.

Department of Pharmaceutics, Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning, 110016, P. R. China.

Carrier-free prodrug-nanoassemblies have emerged as promising nanomedicines. In particular, the self-assembled nanoparticles (NPs) composed of homodimeric prodrugs with ultrahigh drug loading have attracted broad attention. However, most homodimeric prodrugs show poor self-assembly ability due to their symmetric structures. Read More

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Phosphorescent Soft Salt Based on Platinum(II) Complexes: Photophysics, Self-Assembly, Thermochromism, and Anti-counterfeiting Application.

Inorg Chem 2021 Apr 25. Epub 2021 Apr 25.

Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong 999077, P. R. China.

A new platinum(II) complex-based soft salt , ([Pt(tpp)(ed)][Pt(pba) (CN)]) (tpp = 2-(4-(trifluoromethyl)phenyl)pyridine, ed = ethane-1,2-diamine, pba = 4-(2-pyridyl)benzaldehyde), was designed and synthesized. UV-visible absorption and photoluminescence (PL) spectra were studied to elucidate the nature of ground and excited states. The soft salt complex was found to show self-assembly properties with the assistance of electrostatic, π-π stacking, and Pt···Pt interactions, resulting in the remarkable emergence of low-energy absorption and PL bands. Read More

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Size of the hydrogen bond network in liquid methanol: a quantum cluster equilibrium model with extensive structure search.

Phys Chem Chem Phys 2021 Apr;23(15):9166-9175

Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.

Studies have debated what is a favorable cluster size in liquid methanol. Applications of the quantum cluster equilibrium (QCE) model on a limited set of cluster structures have demonstrated the dominance of cyclic hexamers in liquid methanol. In this study, we examined the aforementioned question by integrating our implementation of QCE with a molecular-dynamics-based structural searching scheme. Read More

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The keto-enol tautomerization of ethyl acetoacetate in choline ionic liquids: the role of cation and anion in switching the tautomeric equilibrium.

Phys Chem Chem Phys 2021 Mar 23;23(12):7386-7397. Epub 2021 Mar 23.

Department of Chemistry & Computational Chemistry Laboratory, Loyola Institute of Frontier Energy (LIFE), Loyola College, University of Madras, Chennai 600 034, Tamil Nadu, India.

In this work, density functional theory (DFT) calculations were carried out to study the role of the explicit treatment of four different choline-based ionic liquids (CS, CP, NS, and NP) by utilizing two different cations and anions in the tautomeric equilibrium of ethyl acetoacetate (EAA). The involvement of the acidic N-H proton from the cationic part of NS and NP ionic liquid offers the possibility to have two more additional transition states for the tautomeric equilibrium of EAA. The computed results demonstrated that a high activation free energy barrier (ΔG = 49. Read More

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H, C, N backbone and side-chain resonance assignments of the pathogenic G131V mutant of human prion protein (91-231).

Biomol NMR Assign 2021 Apr 19. Epub 2021 Apr 19.

High-field NMR center, Key Laboratory of Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.

Human prion disease, also known as transmissible spongiform encephalopathy (TSEs), is caused by the conformational conversion of the normal cellular prion protein (PrP) into the scrapie form (PrP). Pathogenic point mutations of prion proteins typically facilitate conformational conversion and lead to inherited prion diseases. A previous study has demonstrated that the pathogenic G131V mutation of human prion protein (HuPrP) brings in Gerstmann-Sträussler-Scheinker syndrome. Read More

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Metalloradical activation of carbonyl azides for enantioselective radical aziridination.

Chem 2021 Apr 29;7(4):1120-1134. Epub 2021 Mar 29.

Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA.

Organic azides have been increasingly employed as nitrogen sources for catalytic olefine aziridination due to their ease of preparation and generation of benign N as the only byproduct. Among common organic azides, carbonyl azides have not been previously demonstrated as effective nitrogen sources for intermolecular olefin aziridination despite the synthetic utilities of N-carbonyl aziridines. As a new application of metalloradical catalysis, we have developed a catalytic system that can effectively employ the carbonyl azide TrocN for highly asymmetric aziridination of alkenes at room temperature. Read More

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Self-reconfigurable high-weight-per-volume-gelatin films for all-solution-processed on-skin electronics with ultra-conformal contact.

Biosens Bioelectron 2021 Jul 15;184:113231. Epub 2021 Apr 15.

Department of Electronic Materials Engineering, Kwangwoon University, Seoul, 01897, South Korea. Electronic address:

Although conventional skin-attachable electronics exhibit good functionalities, their direct attachment (without any adhesive) to human skin with sufficient conformal contact is challenging. Herein, all-solution-processed on-skin electronics based on self-reconfigurable high-weight-per- volume-gelatin (HWVG) film constructed using an effective, biocompatible water absorption-evaporation technique are demonstrated. Completely conformal contact of self-reconfigurable HWVG films is realized by rapidly inducing anisotropic swelling in the perpendicular direction and covering any curvature on the skin without spatial gap or void after shrinking. Read More

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Ultrafast Nonlinear Optical and Structure-Property Relationship Studies of Pyridine-Based Anthracene Chalcones Using -Scan, Degenerate Four-Wave Mixing, and Computational Approaches.

J Phys Chem B 2021 Apr 8;125(15):3883-3898. Epub 2021 Apr 8.

X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, George Town, Penang 11800, Malaysia.

The structural, thermal, linear, and femtosecond third-order nonlinear optical (NLO) properties of two pyridine-based anthracene chalcones, (2)-1-(anthracen-9-yl)-3-(pyridin-2-yl)prop-2-en-1-one () and (2)-1-(anthracen-9-yl)-3-(pyridin-3-yl)prop-2-en-1-one (), were investigated. These two chalcones were synthesized following the Claisen-Schmidt condensation method. Optically transparent single crystals were achieved using a slow evaporation solution growth technique. Read More

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