Role Of Intramolecular Interactions Research Articles

The impact of altered charge on huntingtin aggregation and lipid binding.

Huntington's disease (HD) is a fatal neurodegenerative disease caused by an expansion within the polyglutamine (polyQ) domain of the huntingtin protein (htt), resulting in toxic aggregation. The complex aggregation mechanism is influenced by a variety of factors, including the first 17 amino acids at the N-terminus (Nt17) preceding the polyQ domain and presence of lipid membranes. Nt17 has a propensity to form an amphipathic α-helix which promotes, through intramolecular interactions, the formation of α-helix rich oligomers in which nucleation of fibril formation occurs. The Nt17 amphipathic α-helix also facilitates htt/lipid interactions. Nt17 contains multiple sites of potential post-translational modification. Acetylation occurs at lysine 6, 9, and/or 15 while phosphorylation occurs at threonine 3, serine 13, and/or serine 16. Such modifications affect both aggregation and lipid binding through altering intramolecular interactions (i.e. electrostatics, hydrophobic interactions, and salt-bridges) critical to oligomer formation and stability. A mechanistic understanding of how acetylation and phosphorylation impacts oligomeric intermediates, subsequent aggregation, and lipid interactions can provide critical insights into toxic mechanism and elucidate potential therapeutic targets. The role of intramolecular interactions, most notably electrostatics, in htt interactions with respect to aggregation and lipid binding was measured using a combination of thioflavin-T aggregation assays, colorimetric lipid binding assays, atomic force microscopy, and mass spectrometry. Incubation of free Nt17 peptides (without the polyQ domain) containing point mutations with htt-exon1(46Q) most notably influenced aggregation, with the incorporation of free peptides reducing aggregation relative to htt-exon1(46Q) alone. Oligomers were exposed to lipid vesicles, and those with free Nt17 peptide incorporated minimally impacted interactions relative to those exclusively containing htt-exon1(46Q). Collectively, this suggests that while post-translational modifications impact fibril nucleation within oligomers, charge plays a limited role in facilitating the interaction between htt oligomers and lipid membranes.

Is the phosphorous atom a stereogenic center? Crystallographic findings in five new dithiophosphonate compounds supported with non covalent interaction index (NCI), theoretical approach and spectroscopic analysis

The self-assembly of the dithiophosphonate tectons synthesized in this work generated novel supramolecular synthonsvia NH···S, NH···O, CH···S, CH···O, CH···π, and lp···π interactions. The reaction of the salts with chloro dithiastibocanes X(CH2CH2S)2SbCl (X = O, S) led to the formation of coordination compounds in which the crystal structures showed two new supramolecular synthons stabilized by CH···π and lp···π interactions. The theoretical study of the electronic density of the crystal and their synthons in the solid-state used the robust NCI index to confirm the nature of the interactions found. This study confirmed the connection between molecular and supramolecular chirality in the crystalline state. Three significant features unequivocally support the findings: the role of intramolecular interactions, the electronic density differences among diastereomers, and the nature of trans-annular bonds. The characterization of the salts: ammonium-menthoxy (4-methoxyphenyl) dithiophosphonate (1), triethylammonium-menthoxy (4-methoxyphenyl)-dithiophosphonate (2), triethylammonium-biphenyl-4‑methoxy (4-methoxyphenyl) dithiophosphonate (3), and the coordination compounds O(CH2CH2S)2Sb[S2P(biphenyl-4‑methoxy)(4-MeOC6H4)] (4) and S(CH2CH2S)2Sb[S2P(biphenyl-4‑methoxy)(4-MeOC6H4)] (5) was carried out by elemental analyses, IR, NMR (1H, 13C, 31P), and single-crystal X-ray diffraction analysis.

The role of intramolecular interactions on the stability of the conformers of a spiropyran derivative

DFT level calculations of the thermal isomerization reaction of SP ⇋ MC, in which SP is the spiropyrans derivative 3-(3′,3′-dimethyl-6-nitrospiro[chromene-2,2′-indole]-1′-yl) propanoic acid in the closed-form and MC (merocyanine) is the corresponding open form. An extensively theoretical analysis of the reaction is reported alongside thermodynamics. Scan calculations considered the influence of the carboxyl acid group. Solvents were treated implicitly, and their effects on the MC isomers' geometries, thermodynamics, and electronic parameters were determined. Among several calculated results in good agreement with experimental data, one, in particular, is the description of an intramolecular hydrogen bond in the most stable MC isomer by using the Reduced Density Gradient (RDG) method to perform non-covalent interactions analysis. These results allowed us to evaluate, qualitative and quantitatively, the role of intramolecular interactions in the stability of the structures providing novel results for a better understanding of the complex thermal isomerization process of the spiropyrans.

The Role of Intramolecular Interactions on the Bioactive Conformation of Epinephrine.

The structure of bioactive compounds inside their biological target is mainly dictated by the intermolecular interactions present in the binding side, whereas intramolecular interactions are responsible for the structure of an isolated molecule. Accordingly, this work reports the relative significance of these interactions for the bioactive conformation of the N-protonated epinephrine. The crystallized structure of epinephrine has a gauche orientation of the O-C-C-N torsion angle. Conformational analysis in the gas phase and implicit water was performed to investigate the main intramolecular forces favoring this conformational preference, which was primarily attributed to the electrostatic interaction between hydroxyl and ammonium groups. However, when the conformers were docked into the active site, intramolecular interactions were surpassed by intermolecular hydrogen bonds with neighboring amino acid residues. Nonetheless, structural modifications aiming at strengthening intramolecular interactions could be used to modulate a bioactive conformation, thereby assisting in the structure-based design of new chemical entities.

Editorial

The year 2017 is almost over, the holiday season is only few weeks away. Helvetica celebrates the first anniversary of its relaunch and will celebrate the 100th anniversary of its first published issue in 2018 (January 1918). We take this opportunity to thank the contributors – both authors and reviewers – who have helped to reshape the Journal of the Swiss Chemical Society. There are great promises and great challenges ahead of us. We count on the Swiss community to continue reshaping the journal towards the highest possible standard, defining Swiss quality. Today, we can guarantee a fast turnaround thanks to the commitment of our reviewers, the publishing staff, and our publisher – Wiley. A fully electronic and modern publication platform has helped to improve the submission process and we will continue to do all we can to perfect the journal and improve our services to the authors, reviewers, and readers. Sixty-one articles have already been published since the relaunch, with some downloaded more than 1800 times in less than a year, some cited ten times within few months. While one should be careful with numbers, they are clear indicators that the journal is moving into the right direction and that there is a renewed interest in reading the Journal of the Swiss Chemical Society. This is due to the high quality of timely, impactful molecular science published in Helvetica. We thank all of the Swiss and International authors who have contributed high quality work as a step towards achieving our vision of Helvetica as a journal for world-class science. Although we started the relaunch with a focus on full papers, we have come to appreciate the diminishing distinction between what was once considered a preliminary communication and a detailed document historically associated with a follow up full paper. In response, Helvetica will publish high quality science of any length. We offer the opportunity to include key experimental details in the main text of the article, supplemented by electronic supporting information that provides all the relevant data and protocols for any type of chemistry. We also welcome reviews, perspectives, and comments, such as the widely read article ‘Going for a PhD: Joys and Pitfalls’ published at the start of our relaunch (W. F. van Gunsteren, Helv. Chim. Acta 2016, 99, 755 – 759). We realize that the relaunch has just begun and our jobs are not finished. With the support of the Swiss Chemical Society, Wiley, and our talented staff, we have been granted a rare opportunity to establish a Swiss-based journal that covers all areas of chemistry, offering fast processing times, high visibility, and a personal touch. The next steps in the success of Helvetica solely depend on you and your continuous contribution of high quality papers. We have secured the commitment of the Swiss Chemical Society and Wiley to turn Helvetica into a showcase for the best of Swiss science and a welcoming home to contributions from worldwide. In turn, Helvetica will be able to continue to substantially contribute to key activities of the Swiss Chemical Society, including the annual Swiss Chemical Society meetings, support for young scientists, and the SCS Lectureships. We look forward to reading and to processing your manuscripts in a fast and fair review process. Please help us fulfill the original vision of Helvetica – established 100 years ago by the Swiss Chemical Society as a showcase for Swiss science. We have the rare chance to build a new journal on 100 years of tradition and excellence. But we cannot do it without your support. We wish you the best for the holiday seasons and a successful new year. Manuscripts Published Since the Relaunch of Helvetica W. F. van Gunsteren, ‘Going for a PhD: Joys and Pitfalls’, Helv. Chim. Acta 2016, 99, 755 – 759. S. De Sarkar, J. F. Blom, Y. Bethuel, F. Jüttner, K. Gademann, ‘Allelopathic Activity of the Iron Chelator Anachelin – A Molecular Hybrid with a Dual Mode of Action’, Helv. Chim. Acta 2016, 99, 760 – 773. S. Thamapipol, B. Ludwig, C. Besnard, C. Saudan, E. P. Kündig, ‘Ruthenium Lewis Acid-Catalyzed Asymmetric Diels-Alder Reactions: Reverse-Face Selectivity for α,β-Unsaturated Aldehydes and Ketones’, Helv. Chim. Acta 2016, 99, 774 – 789. J. J. Bürgi, S. Bertrand, F. Marger, D. Bertrand, J.-L. Reymond, ‘Fluorescent Agonists of the α7 Nicotinic Acetylcholine Receptor Derived from 3-Amino-Quinuclidine’, Helv. Chim. Acta 2016, 99, 790 – 804. S. Aroua, E. G. V. Tiu, T. Ishikawa, Y. Yamakoshi, ‘Well-Defined Amphiphilic C60-PEG Conjugates: Water-Soluble and Thermoresponsive Materials’, Helv. Chim. Acta 2016, 99, 805 – 813. F. D. Bobbink, Z. Fei, R. Scopelliti, S. Das, P. J. Dyson, ‘Functionalized Ionic (Poly)Styrenes and their Application as Catalysts in the Cycloaddition of CO2 to Epoxides’, Helv. Chim. Acta 2016, 99, 821 – 829. T. Di Franco, M. Stojanovic, S. C. Keller, R. Scopelliti, X. Hu, ‘A Structure–Activity Study of Nickel NNN Pincer Complexes for Alkyl-Alkyl Kumada and Suzuki–Miyaura Coupling Reactions’, Helv. Chim. Acta 2016, 99, 830 – 847. K. Yamamoto, K. Higashida, H. Nagae, H. Tsurugi, K. Mashima, ‘Synthesis and Characterization of Heterobimetallic Tantalum–Rhodium and Tantalum–Iridium Complexes Connected by a Tantalacyclopentadiene Fragment’, Helv. Chim. Acta 2016, 99, 848 – 858. H.-J. Liu, I. C. Cai, A. Fedorov, M. S. Ziegler, C. Copéret, T. D. Tilley, ‘Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra-High-Molecular Weight Polyethylene in the Absence of Activators’, Helv. Chim. Acta 2016, 99, 859 – 867. F. Thuaud, F. Rohrbacher, A. Zwicky, J. W. Bode, ‘Photoprotected Peptide α-Ketoacids and Hydroxylamines for Iterative and One-Pot KAHA Ligations: Synthesis of NEDD8′, Helv. Chim. Acta 2016, 99, 868 – 894. T. G. Wucherpfennig, S. Müller, C. Wolfrum, J. W. Bode, ‘Chemical Synthesis of the 12 kDa Human Myokine Irisin by α-Ketoacid-Hydroxylamine (KAHA) Ligation’, Helv. Chim. Acta 2016, 99, 897 – 907. M. Rimoldi, A. Mezzetti, ‘Batch and Continuous Flow Hydrogenation of Liquid and Gaseous Alkenes Catalyzed by a Silica-grafted Iridium(III) Hydride’, Helv. Chim. Acta 2016, 99, 908 – 915. P. Wolf, W.-C. Liao, T.-C. Ong, M. Valla, J. W. Harris, R. Gounder, W. N. P. van der Graaff, E. A. Pidko, E. J. M. Hensen, P. Ferrini, J. Dijkmans, B. Sels, I. Hermans, C. Copéret, ‘Identifying Sn Site Heterogeneities Prevalent Among Sn-Beta Zeolites’, Helv. Chim. Acta 2016, 99, 916 – 927. A. Brunner, L. Hintermann, ‘Configurational Assignment of ‘Cryptochiral’ 10-Hydroxystearic Acid Through an Asymmetric Catalytic Synthesis’, Helv. Chim. Acta 2016, 99, 928– 943. R. Nakayama, E.-M. Tanzer, T. Kusumi, K. Ohmori, K. Suzuki, ‘Total Synthesis of the Proposed Structure of Ardimerin, and Proposal for its Structural Revision’, Helv. Chim. Acta 2016, 99, 944 – 960. J.-M. Lehn, ‘A tribute to Albert Eschenmoser: On the occasion of his 90th Anniversary and of the 100th Anniversary of Helvetica Chimica Acta’, Helv. Chim. Acta 2017, 100, e1770013. W. R. Grüning, H. Bieringer, M. Schwarzwälder, D. Gajan, A. Bornet, B. Vuichoud, J. Milani, D. Baudouin, L. Veyre, A. Lesage, S. Jannin, G. Bodenhausen, C. Thieuleux, C. Copéret, ‘Phenylazide Hybrid-Silica – Polarization Platform for Dynamic Nuclear Polarization at Cryogenic Temperatures’, Helv. Chim. Acta 2017, 100, e1600122. A. Lonardi, P. Oborský, P. H. Hünenberger, ‘Solvent-Modulated Influence of Intramolecular Hydrogen-Bonding on the Conformational Properties of the Hydroxymethyl Group in Glucose and Galactose: A Molecular Dynamics Simulation Study’, Helv. Chim. Acta 2017, 100, e1600158. J. Li, C. Wäckerlin, S. Schnidrig, E. Joliat, R. Alberto, K.-H. Ernst, ‘On-Surface Metalation and 2D Self-Assembly of Pyrphyrin Molecules Into Metal-Coordinated Networks on Cu(111)’, Helv. Chim. Acta 2017, 100, e1600278. M. Kuss-Petermann, O. S. Wenger, ‘Pump-Pump-Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation’, Helv. Chim. Acta 2017, 100, e1600283. S. Wendeborn, M. Lachia, P. M. J. Jung, J. Leipner, D. Brocklehurst, A. De Mesmaeker, K. Gaus, R. Mondière, ‘Biological Activity of Brassinosteroids – Direct Comparison of Known and New Analogs in planta’, Helv. Chim. Acta 2017, 100, e1600305. D. Mazunin, J. W. Bode, ‘Potassium Acyltrifluoroborate (KAT) Ligations are Orthogonal to Thiol-Michael and SPAAC Reactions: Covalent Dual Immobilization of Proteins onto Synthetic PEG Hydrogels’, Helv. Chim. Acta 2017, 100, e1600311. T. Miura, T. Tanaka, Q. Zhao, S. G. Stewart, M. Murakami, ‘Synthesis of 2-Substituted 2-Amino Ketones by Rhodium-Catalyzed Reaction of N-Sulfonyl-1,2,3-triazoles with 2-Alkenols’, Helv. Chim. Acta 2017, 100, e1600320. Q. Verolet, M. Dal Molin, A. Colom, A. Roux, L. Guénée, N. Sakai, S. Matile, ‘Twisted Push-Pull Probes with Turn-On Sulfide Donors’, Helv. Chim. Acta 2017, 100, e1600328. D. Garayalde, G. Rusconi, C. Nevado, ‘A Gold- and Brønsted Acid Catalytic Interplay Towards the Synthesis of Highly Substituted Tetrahydrocarbazoles’, Helv. Chim. Acta 2017, 100, e1600333. Y. Zhang, S. Wu, J. Yan, ‘PhI Catalyzed Acetoxyselenylation and Formyloxyselenylation of Alkenes’, Helv. Chim. Acta 2017, 100, e1600306. M. L. Campbell, D. Sulejmanovic, J. B. Schiller, E. M. Turner, S.-J. Hwu, D. C. Whitehead, ‘Alcohol Oxidations Using Reduced Polyoxovanadates’, Helv. Chim. Acta 2017, 100, e1600338. P. Morelli, S. Matile, ‘Sidechain Engineering in Cell-Penetrating Poly(disulfide)s’, Helv. Chim. Acta 2017, 100, e1600370. Z. Li, L. Yu, J. Yuan, Y. Ye, Y. He, B. Huang, X. Gao, ‘8-Hydroxy Quinoline Derivatives as Auxiliary Ligands for Red-Emitting Cyclic-Platinum Phosphorescent Complexes: Synthesis and Properties’, Helv. Chim. Acta 2017, 100, e1600308. L. Hintermann, P. J. Altmann, P. Naumov, K. Suzuki, ‘Synthesis of Tetraoxygenated Terephthalates via a Dichloroquinone Route: Characterization of Cross-Conjugated Liebermann Betaine Intermediates’, Helv. Chim. Acta 2017, 100, e1600392. M. Lehmann, E. H. Peters, M. Mayor, ‘Size Matters: Influence of Gold-to-Ligand Ratio and Sulfur-Sulfur Distance of Linear Thioether Heptamers on the Size of Gold Nanoparticles’, Helv. Chim. Acta 2017, 100, e1600395. F. M. Miloserdov, A. I. Konovalov, E. Martin, J. Benet-Buchholz, E. C. Escudero-Adán, A. Lishchynskyi, V. V. Grushin, ‘The Trifluoromethyl Anion: Evidence for [K(crypt-222)]+ CF3−’, Helv. Chim. Acta 2017, 100, e1700032. S. Luginbühl, F. Iwasaki, E. Chirackal Varkey, H. Umakoshi, P. Walde, ‘A Novel Role of Vesicles as Templates for the Oxidation and Oligomerization of p-Aminodiphenylamine by Cytochrome c’, Helv. Chim. Acta 2017, 100, e1700027. A. R. N. S. Royappa, M. Ayer, A. Fracassi, M.-O. Ebert, S. Aroua, Y. Yamakoshi, ‘Conformationally Selective Synthesis of Mononitrocalix[4]arene in Cone or Partial Cone’, Helv. Chim. Acta 2017, 100, e1600391. B. Commare, A. Togni, ‘Hypervalent Iodine Reagents: Thiol Derivatization with a Tetrafluoroethoxy Coumarin Residue for UV Absorbance Recognition’, Helv. Chim. Acta 2017, 100, e1700059. A. Roussey, E. Martinez, C. Copéret, C. Thieuleux, V. Jousseaume, ‘Cu Nanoparticles on TiN by Electroless Deposition: Surface-Mediated Diameter Control and Application to Si Nanowires Growth’, Helv. Chim. Acta 2017, 100, e1700018. N. Hérault, K. M. Fromm, ‘Influence of the Sacrificial Polystyrene Removal Pathway on the TiO2 Nanocapsule Structure’, Helv. Chim. Acta 2017, 100, e1700014. A. Prlj, L. Vannay, C. Corminboeuf, ‘Fluorescence Quenching in BODIPY Dyes: The Role of Intramolecular Interactions and Charge Transfer’, Helv. Chim. Acta 2017, 100, e1700093. D. L. Silverio, H. A. van Kalkeren, T.-C. Ong, M. Baudin, M. Yulikov, L. Veyre, P. Berruyer, S. Chaudhari, D. Gajan, D. Baudouin, M. Cavaillès, B. Vuichoud, A. Bornet, G. Jeschke, G. Bodenhausen, A. Lesage, L. Emsley, S. Jannin, C. Thieuleux, C. Copéret, ‘Tailored Polarizing Hybrid Solids with Nitroxide Radicals Localized in Mesostructured Silica Walls’, Helv. Chim. Acta 2017, 100, e1700101. P. R. Varadwaj, ‘Methylammonium Lead Trihalide Perovskite Solar Cell Semiconductors Are Not Organometallic: A Perspective’, Helv. Chim. Acta 2017, 100, e1700090. A. Chiminazzo, M. Damuzzo, L. Sperni, G. Strukul, A. Scarso, ‘Nitrile Containing Bisphosphonates: Easy Synthesis through Metal Catalyzed Michael Addition’, Helv. Chim. Acta 2017, 100, e1700104. M. Ghazanfarpour-Darjani, F. Barat-Seftejani, M. Khalaj, S. M. Mousavi-Safavi, ‘Synthesis of N-alkyl-N’-aryl or Alkenylpiperazines: A Copper-Catalyzed C–N Cross-Coupling in the Presence of Aryl and Alkenyl Triflates and DABCO’, Helv. Chim. Acta 2017, 100, e1700082. L. Hu, Y. Zhao, ‘Cross-Linked Micelles with Enzyme-Like Active Sites for Biomimetic Hydrolysis of Activated Esters’, Helv. Chim. Acta 2017, 100, e1700147. F. J. Widner, F. Gstrein, B. Kräutler, ‘Partial Synthesis of Coenzyme B12 from Cobyric Acid’, Helv. Chim. Acta 2017, 100, e1700170. S. Behrouz, M. N. Soltani Rad, M. A. Piltan and M. M. Doroodmand, ‘Chitosan-Silica Sulfate Nano Hybrid as a Novel and Highly Proficient Heterogeneous Nano Catalyst for Regioselective Ring Opening of Epoxides via Carboxylic Acids’, Helv. Chim. Acta 2017, 100, e1700144. E. Hartmann, S. E. Denmark, ‘Structural, Mechanistic, Spectroscopic, and Preparative Studies on the Lewis Base Catalyzed, Enantioselective Sulfenofunctionalization of Alkenes’, Helv. Chim. Acta 2017, 100, e1700158. T. Husch, D. Seebach, A. K. Beck, M. Reiher, ‘Rigorous Conformational Analysis of Pyrrolidine Enamines with Relevance to Organocatalysis’, Helv. Chim. Acta 2017, 100, e1700182. K. Root, R. Frey, D. Hilvert, R. Zenobi, ‘High-Mass MALDI-MS Analysis for the Investigation of Protein Encapsulation within an Engineered Capsid Forming Protein’, Helv. Chim. Acta 2017, 100, e1700166. P. E. Sues, K. V. Bukhryakov, R. R. Schrock, ‘Evaluation of Several Molybdenum and Ruthenium Catalysts for the Metathesis Homocoupling of 3-Methyl-1-Butene’, Helv. Chim. Acta 2017, 100, e1700181. L. N. Jeanbourquin, R. Scopelliti, F. F. Tirani, K. Severin, ‘Gold-Catalyzed Synthesis of 1,3-Diaminopyrazoles from 1-Alkynyltriazenes and Imines’, Helv. Chim. Acta 2017, 100, e1700186. M. U. Luescher, T. Songsichan, S.-Y. Hsieh, J. W. Bode, ‘Copper Promoted Oxidative Coupling of SnAP Hydrazines and Aldehydes to Form Chiral 1,4,5-Oxadiazepanes and 1,2,5-Triazepanes’, Helv. Chim. Acta 2017, 100, e1700199. T. Miletić, A. Fermi, I. Papadakis, I. Orfanos, N. Karampitsos, A. Avramopoulos, N. Demitri, F. De Leo, S. J. A. Pope, M. G. Papadopoulos, S. Couris, D. Bonifazi, ‘A Twisted Bay-Substituted Quaterrylene Phosphorescing in the NIR Spectral Region’, Helv. Chim. Acta 2017, 100, e1700192. O. D. Engl, J. Saadi, E. Cosimi, H. Wennemers, ‘Synthesis of Monothiomalonates – Versatile Thioester Enolate Equivalents for C–C Bond Formations’, Helv. Chim. Acta 2017, 100, e1700196. A. Bielmann, C. Curty, C. G. Bochet, ‘Solid-phase Synthesis of the Aged-Nonapeptide-Nerve-Agent Adduct of Butyrylcholinesterase as Reference Materials for Analytical Verification’, Helv. Chim. Acta 2017, 100, e1700198. S. Ghosh, A. Spannenberg, E. Mejía, ‘Cubane-type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring-Opening Polymerization Studies of rac-Lactide and ε-Caprolactone’, Helv. Chim. Acta 2017, 100, e1700176. J. Liu, Y. Zou, L. Zhou, A. Chai, C. Wang, H.-S. Dang, Q. Wang, A. Goeke, ‘A Practical Domino-Claisen–Cope Sequence in the Synthesis of New Blooming Citrus and Potent Floral Rose Alcohols’, Helv. Chim. Acta 2017, 100, e1700200. J. I. Seeman, ‘R. B. Woodward's Letters: Revealing, Elegant and Commanding’, Helv. Chim. Acta 2017, 100, e1700183. S. Milicevic Sephton, P. T. Vetterli, V. Pedani, S. Cermak, A. Chiotellis, S. Roscales, A. Müller Herde, R. Schibli, Y. P. Auberson, S. M. Ametamey, ‘Synthesis and Biological Evaluation of Quinoxaline Derivatives for PET Imaging of the NMDA Receptor’, Helv. Chim. Acta 2017, 100, e1700204. J. Wang, R. Gao, N. Zhang, X. Tan, L. Wang, L. Ma, W. Shi, ‘Novel Dendritic PNP Chromium Complexes: Synthesis, Characterization and Performance on Ethylene Oligomerization’, Helv. Chim. Acta 2017, 100, e1700162. P. Caramenti, J. Waser, ‘Bench-Stable Electrophilic Indole and Pyrrole Reagents: Serendipitous Discovery and Use in C–H Functionalization’, Helv. Chim. Acta 2017, 100, e1700221. M. G. Shopska, D. G. Paneva, H. G. Kolev, G. B. Kadinov, R. Ilieva, M. Iliev, Z. P. Cherkezova-Zheleva, I. G. Mitov, ‘Bioinspired Synthesis of Lepidocrocite-Containing Material and its Catalytic Behaviour in CO Oxidation’, Helv. Chim. Acta 2017, 100, e1700172.

Extraction of U(VI) by the ionic liquid hexyltributylphosphonium bis(trifluoromethylsulfonyl)imides: An experimental and theoretical study

Abstract In the extraction of U(VI) by tri-n-butyl phosphate (TBP) in bis(trifluoromethylsulfonyl)imides (NTf2−) based ionic liquids (ILs), an unexpected high distribution ratio was observed when P6,4,4,4NTf2 was used as the solvent, where P6,4,4,4+ is hexyltributylphosphonium. Further research showed that P6,4,4,4NTf2 was able to extract U(VI) in the absence of extractants, and the extraction ability of P6,4,4,4NTf2 was attributed to the combination of the outer-sphere interaction between NTf2− and U(VI) and the intramolecular interaction between NTf2− and P6,4,4,4+. The outer-sphere interaction of NTf2− with U(VI) was theoretically explored by DFT calculation. Walden plot were employed to discover the intramolecular interaction in ILs, among which P6,4,4,4NTf2 showed a much stronger intramolecular interaction than other NTf2− based ILs. Stripping of U(VI) from P6,4,4,4NTf2 was also investigated by use of supercritical carbon dioxide (Sc-CO2). This work shed a light on the role of intramolecular interactions in ILs in the extraction of metal ions.

Fluorescence Quenching in BODIPY Dyes: The Role of Intramolecular Interactions and Charge Transfer

The fluorescence properties of the BODIPY dye and its two meso-substituted derivatives, tert-butyl- and phenyl-BODIPY, are rationalized. The non emissive behavior of the latter two are attributed to the energetically accessible low-lying conical intersection between the ground state and the lowest excited singlet state. Both intramolecular non-covalent interactions and excited state charge transfer character are identified as being crucial for “stabilizing” the intersection and prompting the nonradiative decay. Similar crossing was located in the bare BODIPY dye, however, being energetically less accessible, which correlates well with the high fluorescence quantum yields of the parent dye.

Theoretical Studies on the Energetic Salts of Substituted 3,3′-Amino-N,N′-azo-1,2,4-triazoles: The Role of Functional Groups

Thirty energetic salts formed by substituted 3,3′-amino-N,N′-azo-1,2,4-triazoles (A to F) with functional groups (−H, −NH2, −CH3, −N3, −NO2 or −NF2) and acids (HCl (I), HNO3 (II), HClO4 (III), HN(NO2)2 (IV) and HC(NO2)3 (V)) were studied using the density functional theory (DFT). The proton (H1) of an acid plays a more important role in intramolecular interactions than the other H atoms. The electron withdrawing groups −N3, −NF2, and −NO2 improve the positive charge on the H1 compared to that of series A without substituent, which results in the stronger intramoleuclar hydrogen bonding interaction and second perturbation interaction, the opposite effects were caused by the electron donating groups −CH3 and −NH2. −N3, −NF2 and −NO2 gradually enhance density, heat of formation, and detonation performance, while −NH2 and −CH3 lower those characteristics. IIID to IIIF, IVE to IVF, and VE to VF have detonation properties (D = 9.49 km/s to 10.72 km/s, P = 43.51 GPa to 58.14 GPa, Is = 260 s to 291 s); they can b...

Intramolecular Interactions versus Hydration Effects on p-Guanidinoethyl-phenol Structure and pKa Values

We analyze the structure, hydration, and pK(a) values of p-guanidinoethyl-phenol through a combined experimental and theoretical study. These issues are relevant to understand the mechanism of action of the tetrameric form, the antibacterial compound tetra-p-guanidinoethyl-calix[4]arene (Cx1). The investigated system can also be useful to model other pharmaceutical drugs bearing a guanidine function in the vicinity of an ionizable group and the effect of arginine on the pK(a) of vicinal ionizable residues (in particular tyrosine) in peptides. The p-guanidinoethyl-phenol monomer (mCx1) has two ionizable groups. One important particularity of this system is that it exhibits high molecular flexibility that potentially leads to enhanced stabilization in folded structures by direct, strong Coulombic interactions between the ionizable groups. The first pK(a) corresponding to ionization of the -OH group has experimentally been shown to be only slightly different from usual values in substituted phenols. However, because of short-range Coulombic interactions, the role of intramolecular interactions and solvation effects on the acidities of this compound is expected to be important and it has been analyzed here on the basis of theoretical calculations. We use a discrete-continuum solvation model together with quantum-mechanical calculations at the B3LYP level of theory and the extended 6-311+G(2df,2p) basis set. Both intra- and intermolecular effects are very large (~70 kcal/mol) but exhibit an almost perfect compensation, thus explaining that the actual pK(a) of mCx1 is close to free phenol. The same compensation of environmental effects applies to the second pK(a) that concerns the guanidinium group. Such a pK(a) could not be determined experimentally with standard titration techniques and in fact the theoretical study predicts a value of 14.2, that is, one unit above the pK(a) of the parent ethyl-guanidinium molecule.

Organoselenium Chemistry: Role of Intramolecular Interactions

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTOrganoselenium Chemistry: Role of Intramolecular Interactions†Anna J. Mukherjee‡, Sanjio S. Zade§, Harkesh B. Singh*‡, and Raghavan B. Sunoj‡View Author Information Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India, and Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741252, Nadia, West Bengal, India* Corresponding author.†Dedicated to late Professor William R. McWhinnie, Department of Chemical Engineering and Applied Chemistry, Aston University, Birmingham B4 7ET, U.K.‡Indian Institute of Technology Bombay.§Indian Institute of Science Education and Research Kolkata.Cite this: Chem. Rev. 2010, 110, 7, 4357–4416Publication Date (Web):April 12, 2010Publication History Received26 October 2009Published online12 April 2010Published inissue 14 July 2010https://doi.org/10.1021/cr900352jCopyright © 2010 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views8598Altmetric-Citations400LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (3 MB) Get e-AlertsSUBJECTS:Anions,Crystal structure,Ligands,Nitrogen,Selenium Get e-Alerts

Self-consistent field/density functional study of conformational properties of polymers at interfaces: Role of intramolecular interactions

We study the properties of athermal polymers at hard walls using two different versions of self-consistent field theory (SCFT). We calculate the segment density profiles, center of mass profiles, bond orientation vector profiles, and end-to-end vector distributions and compare with grand canonical Monte Carlo simulations. Using the same excess free energy prescription for both theories, we investigate the role of the excluded volume intramolecular interactions on these properties, show the relation between SCFT and density functional theory, and discuss several numerical implementations of the SCFT method. The phantom chain model gives Gaussian chain statistics independent of the conditions. Including the full intramolecular potential leads to an improved description of the low density regime but it does not produce any significant improvement in the semidiluted and concentrated regimes. We show that a viable compromise is achieved by using the effective field resulting from the phantom chain model and by calculating single chain properties using the full intramolecular potential.

Role of intramolecular interaction in connexin50: Mediating the Ca 2+-dependent binding of calmodulin to gap junction

Gap junction channels formed by connexin50 (Cx50) are critical for maintenance of eye lens transparency. Cleavage of the carboxyl terminus (CT) of Cx50 to produce truncated Cx50 (Cx50trunc) occurred naturally during maturation of lens fiber cells. The mechanism of its altered properties is under confirmation. It has been suggested that calmodulin (CaM) participates in gating some kinds of gap junction. Here, we performed confocal colocalization and co-immunoprecipitation experiments to study the relationships between Cx50 and CaM. Results exhibited that the CaM could colocalize Ca 2+ dependently with CT in the linear area of cell-to-cell contact formed by Cx50trunc, while it could not localize in the linear area without expression of CT. Further study indicated that the CT could interact Ca 2+ independently with the cytoplasmic loop (CL) of Cx50. These data put forward the importance of Ca 2+-independent intramolecular interaction between CT and CL of Cx50, which mediate the Ca 2+-dependent binding of CaM to Cx50. These intra- and intermolecular interactions may further improve our understanding of biological significance of the Cx50 in the eye lens.

Role of intramolecular interactions in Raman spectra of N 2 and O 2 molecules

The effect of vibration–rotation interactions and anharmonicities on the polarizabilities matrix elements, Raman scattering cross-sections, and depolarization degrees of N 2 and O 2 molecules for vibrational transitions v→ v, v+1, v+2, v+3 have been investigated.

Conformational study of α,2-dimethylstyrene: Raman and FT-IR spectra and ab initio calculations

Vibrational spectra (Raman and FT-IR) of liquid phase and ab initio SCF MO calculations at the B3LYP/6-31G* level are reported for α,2-dimethylstyrene. The calculations predict two minima with different orientations of the CC double bond relative to the 2-methyl group, but only the minimum with θ (C 2C 1C αC β)=112° (named skew) is deep enough to accommodate torsional levels. The role of intramolecular interactions on the conformational preferences is accessed through the comparison of the ab initio results for α,2-, α,3- and α,4-dimethylstyrene. The Raman spectra of the liquid sample show pairs of bands whose temperature-dependent intensities are ascribed to a conformational equilibrium. From the plot of logarithm of intensity ratio vs. inverse temperature, a Δ H value of 1.1±0.1 kJ mol −1 has been derived. The temperature-dependence of other Raman bands with no measurable conformational splitting can also be related with the conformational equilibrium by assuming different molar Raman intensities. The comparison of the experimental and calculated wavenumber shifts suggests that the gauche form is more stable than the skew form in the liquid, while ab initio results predict a single skew form for the isolated molecule. This discrepancy may arise from intermolecular interactions in the liquid.

Ultrafast Collisional Redistribution of Vibrational Energy in Highly Excited Polyatomic Molecules. The Role of Intramolecular Interactions

AbstractTime‐resolved Raman probing technique is used to investigate the collisional relaxation of high‐lying C‐H vibrations in CHF3 and CHF2Cl molecules. The relaxation rates both in collisions with parent molecules and a number of buffer gases were measured. The rate values were found to be abnormally fast. The relaxation is faster than single collision in parent gas and requires a few (3‐8) collisions for nonpolar gases. For polar gases the relaxation is still faster.The conclusion is made that observed ultrafast relaxation of C–H modes is caused by energy transfer from excited “bright” states to nearby “dark” ones. Possible mechanisms of the above transfer are discussed.