DOCSLIB.ORG

A Practical Guide to the Design of Molecular Crystals Published As Part of a Crystal Growth and Design Virtual Special Issue Honoring Prof

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Practical Guide to the Design of Molecular Crystals Published As Part of a Crystal Growth and Design Virtual Special Issue Honoring Prof This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Review Cite This: Cryst. Growth Des. 2019, 19, 1426−1453 pubs.acs.org/crystal A Practical Guide to the Design of Molecular Crystals Published as part of a Crystal Growth and Design virtual special issue Honoring Prof. William Jones and His Contributions to Organic Solid-State Chemistry Meriná K. Corpinot and Dejan-Kresimiř Bucař* Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom ABSTRACT: This Tutorial Review, aimed at both the novice and the seasoned solid-state chemist, provides a succinct overview of key findings that have, over the last half century, advanced our ability to make molecular crystals with targeted structures and desired properties. The article critically evaluates the efficiency and reliability of the well-established guidelines used by experimentalists in crystal engineering and highlights statistical and computational tools that are both advantageous to crystal design and accessible to experimental solid-state chemists. The systematic development of our subject will be difficult if the market requires an average investment exceeding 2.6 not impossible until we understand the intermolecular forces billion USD over more than a decade.9 The intensive responsible for the stability of the crystalline lattice of investment demanded by research and development (R&D) organic compounds; a theory of the organic solid state is a activities, and the need to rapidly respond to societal needs in requirement for the eventual control of molecular packing an efficient and environmentally friendly manner, drive current arrangement. Once such a theory exists we shall, in the efforts to minimize the cost, time, and risk associated with such present context of synthetic and mechanistic photochemistry, R&D projects. With this in mind, computational methods have ‘ ’ be able to engineer crystal structures having intermolecular been introduced into R&D to guide the fine-tuning of specialty contact geometry appropriate for chemical reaction, much chemicals.10 as, in other contexts, we shall construct organic conductors, The last three decades have also witnessed remarkable catalysts, etc. In short, any rational development of the advances in computational solid-state chemistry, advances physics and chemistry of the solid state must be based upon underpinned by continuously increasing computational pro- a theory of molecular packing; since the molecules studied cessing power and expanded funding for accessible super- are complex, the theory will most likely be empirical for computers. These advances have enabled the use of materials some time yet. Rules are now becoming available in what I modeling and crystal structure prediction of inorganic Downloaded via UNIV COLLEGE LONDON on February 21, 2019 at 14:10:40 (UTC). regard as phase three, the phase of crystal engineering. materials such as metal oxides11 and zeolites.12 Substantial 1 See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. G. M. J. Schmidt progress has also been made when it comes to the modeling of organic solids: for instance, recent reports describe the use of 1. INTRODUCTION crystal structure prediction and property calculations to accurately describe a range of feasible crystal structures and For centuries, molecular solids have been used as key the accompanying electronic13,14 or host−guest15,16 properties components in medicines,2 fertilizers,3 pesticides,4 inks and of a molecular compound in the solid state. This was paints.5 Their potential to perform as highly functional accomplished within a time frame that is appreciably shorter electronic and optical materials has recently also inspired the 6 than that needed to synthesize, characterize and test the solid- development of crystalline molecular semiconductors and 16 optoelectronics.7 The transformation of specialty chemicals state properties of the very same molecule. Given such into fit-for-purpose crystalline solids is a lengthy and expensive achievements, as well as the predictive accuracy and speed of process, one which, unfortunately, often fails to generate a the computational methods which are beginning to shape our marketable product due to a multitude of unfulfilled perform- pursuit of functional materials, it is reasonable to expect that ance and safety requirements (many of which are associated such predictive methods will soon become a cornerstone of with the solid-state properties of the target compound). The materials science. risky nature of such endeavors is best appreciated by considering the drug attrition rates in the pharmaceutical Received: June 26, 2018 industry,8 where the placement of an FDA-approved drug onto Published: December 6, 2018 © 2018 American Chemical Society 1426 DOI: 10.1021/acs.cgd.8b00972 Cryst. Growth Des. 2019, 19, 1426−1453 Crystal Growth & Design Review − This is particularly true of crystal engineering,1,17 23 a field concepts, theories, and ideas discussed herein and feel that deals with the design, synthesis, and use of molecular and encouraged to further develop the same. Although the field metal−organic crystals.24 This branch of solid-state chemistry has advanced significantly in the last two decades, the initial is primarily concerned with the synthesis of targeted solid-state goal of crystal engineersnamely, the development of a full structures that have desired properties, through an under- understanding of the intermolecular interactions that control standing and control of intermolecular interactions in the the structure and function of molecular crystals18is still crystal.19 Surprisingly, crystal engineering endeavors (at least unfulfilled. Considering that the focus in crystal engineering those pursued in academic circles) rarely involve the has progressively shifted from structure to function,41,42 it is manipulation of particle properties such as morphology, vital to reiterate Schmidt’s message from the epigraph to this particle size, and particle-size distribution, although such review: “the systematic development of our subject will be approaches meaningfully alter physicochemical solid-state difficult if not impossible until we understand the intermo- − properties of organic molecules.25 28 The crystal engineer’s lecular forces responsible for the stability of the crystalline aspiration to design materials with absolute meticulousness is lattice of organic compounds”.1 Such systematic advancement challenged by the fact that trivial changes to the molecular of crystal engineering can only be achieved through the structures (e.g., a H/F atom exchange) regularly result in continuous refinement of extant models, the construction of significantly and unpredictably altered crystal packing,29,30 entirely new models as necessary, and, crucially, rigorous while more profound changes (e.g., addition of hydrogen- testing of these models via well-crafted experiments. We bonding groups) might even affect the dimensionality and therefore hope that this review will prompt the practicing solid- topology of supramolecular solid-state structures.31,32 It is state chemist to rethink current crystal engineering practices therefore important that crystal engineers and solid-state and to consider the implementation of emerging predictive chemists develop design guidelines that are as practical and methods43 into their research programs to develop and test reliable as the synthetic blueprints that organic synthetic new theories. With this Tutorial Review, we also intend to chemists developed throughout the last century.33 complement other recent works along similar lines,44,45 by The crystal engineer and experimental organic solid-state providing a more holistic view of the topic at hand (rather than chemist generally resort to “predictive” guidelines that are focusing on particular aspects, such as the synthon approach) mainly derived from crystallographic studies, extensive surveys and by emphasizing promising statistical and computational of databases (such as the Cambridge Structural Database;34,35 tools for the design of molecular crystals that are easily 24 CSD), and other empirical data. While such guidelines are accessible to experimental solid-state chemists. useful when making alterations of the supramolecular patterns The reader should keep in mind that the scope of this review in a molecular crystal, their use does not permit the is limited to the design of crystals exclusively comprised of preparation of solids with targeted crystal structures, molecular entities (i.e., metal−organic crystals are excluded) particularly when molecules with a diverse range of functional and that the design principles and guidelines featured here are groups are involved. Nevertheless, such controlled changes to those that the authors regard as most relevant, established, and crystal structures based on these guidelines have been used to reliable. The nonspecialist is also referred to articles by 46 47 modulate (and often improve) the properties of a wide range Aitipamula et al. and Lusi for definitions of various types of of specialty chemicals that are central to modern living (e.g., multicomponent molecular crystals that will be discussed drug molecules,36 nutraceuticals,37 semiconductors,38 energetic herein. compounds39). There are thus numerous real-world examples that demonstrate the utility of crystal engineering
Load more

Recommended publications
  • Application with the Even-Odd Rule and a Specific Periodic Table for Organic and Inorganic Atoms
    Open Journal of Physical Chemistry, 2021, 11, 54-63 https://www.scirp.org/journal/ojpc ISSN Online: 2162-1977 ISSN Print: 2162-1969 First Step in Dissociation Process in the Gas Phase for Small Molecules with Neutral Atoms: Application with the Even-Odd Rule and a Specific Periodic Table for Organic and Inorganic Atoms Geoffroy Auvert Grenoble Alpes University, Grenoble, France How to cite this paper: Auvert, G. (2021) Abstract First Step in Dissociation Process in the Gas Phase for Small Molecules with Neutral Dissociations in the gas phase of small molecules have been intensively stu- Atoms: Application with the Even-Odd died and dissociation energies of various gases are available in reference Rule and a Specific Periodic Table for Or- works. Configurations of compounds before and after the dissociation are ganic and Inorganic Atoms. Open Journal of Physical Chemistry, 11, 54-63. usually known, but local charges are not defined. Building on the even-odd https://doi.org/10.4236/ojpc.2021.112003 rule, the topic of a series of previous articles by the same author, the objective of this paper is to show how it can be used to give electronic rules for dissoci- Received: March 17, 2021 Accepted: May 17, 2021 ations in gases. To this end, a specific periodic table is created and used. The Published: May 20, 2021 rules are applied to a selection of more than 30 common molecules, showing that the even-odd rule and its consequences are useful in explaining the phe- Copyright © 2021 by author(s) and nomenon of dissociation in gases.
    [Show full text]
  • Open Dissertation Xiang Li 07032018.Pdf
    The Pennsylvania State University The Graduate School Department of Chemistry MECHANOCHEMICAL SYNTHESIS OF CARBON AND CARBON NITRIDE NANOTHREAD SINGLE CRYSTALS A Dissertation in Chemistry by Xiang Li 2018 Xiang Li Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2018 The dissertation of Xiang Li was reviewed and approved* by the following: John V. Badding Professor of Chemistry, Physics and Materials Science and Engineering Dissertation Advisor Chair of Committee Vincent H. Crespi Professor of Physics, Materials Science and Engineering, and Chemistry Paul S. Cremer Professor of Chemistry and Biochemistry and Molecular Biology Mauricio Terrones Professor of Physics, Chemistry and Materials Science and Engineering Thomas E. Mallouk Professor of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics Head of the Department of Chemistry *Signatures are on file in the Graduate School iii ABSTRACT Carbon nanomaterials such as fullerenes, nanotubes, and graphene have been widely studied in recent decades. Benefitting from their unique bonding, they possess extraordinary physical and chemical properties. Compared with sp2 hybridized carbon allotropes, there are significantly fewer new carbon materials dominated by sp3 bonding that have been developed. Adamantane and graphane represent the smallest unit and thinnest sheet of diamond possible, respectively. One-dimensional, mostly sp3 hybridized nanocarbon, did not yet exist in 2013, when the first synthesis of carbon nanothreads finally filled up the last remaining entry in the matrix of dimensionality and hybridization of carbon nanomaterials that year. Carbon nanothread was first made by compressing benzene to ~25 GPa in a large-volume anvil cell and slowly decompressing back to ambient pressure by an alumnus of the Badding group.
    [Show full text]
  • Inorganic Chemistry for Dummies® Published by John Wiley & Sons, Inc
    Inorganic Chemistry Inorganic Chemistry by Michael L. Matson and Alvin W. Orbaek Inorganic Chemistry For Dummies® Published by John Wiley & Sons, Inc. 111 River St. Hoboken, NJ 07030-5774 www.wiley.com Copyright © 2013 by John Wiley & Sons, Inc., Hoboken, New Jersey Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permis- sion of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley. com/go/permissions. Trademarks: Wiley, the Wiley logo, For Dummies, the Dummies Man logo, A Reference for the Rest of Us!, The Dummies Way, Dummies Daily, The Fun and Easy Way, Dummies.com, Making Everything Easier, and related trade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries, and may not be used without written permission. All other trade- marks are the property of their respective owners. John Wiley & Sons, Inc., is not associated with any product or vendor mentioned in this book.
    [Show full text]
  • Femtosecond X-Ray Diffraction
    AMERICAN CRYSTALLOGRAPHIC ASSOCIATION Number 2 Summer 2012 Femtosecond X-Ray Diffraction American Crystallographic Association ACA HOME PAGE: www.amercrystalassn.org Table of Contents 2 President’s Column What’s on the Cover 3 News from Canada - page 40 4 ACA Balance Sheet 5 From the Editor’s Desk IUCr Partners with AIP UniPHY Errata 6 News from Argentina Contributors to this Issue / Bruker Awards 8 Puzzle Corner 9-10 Book Reviews 11-20 ACA History The Early Days of the ACA David Sayre (1924 - 2012) 21 AIP Inside Science 22 ACA Corporate Members 23-31 Candidates for ACA Officers and Committees for 2012 32 ACA Trueblood Award to Tom Terwilliger ACA Fankuchen Award to Richard Dickerson 34-35 Carl Branden Award to Helen Berman AIP Andrew Gemant Award to Lisa Randall Golden Mouse Award to Crystallographic iPhone app Awards Available / Travel and Fellowships 36 Scientific Controversies and Crystallography 37 Big Data Initiative 38 ACA 2012 Student Award Winners 39 ACA 2012 Exhibitors and Sponsors / ACA 2013 - Hawaii - Preview 40 Future Meetings / Index of Advertisers What’s on the Cover ACA RefleXions staff: Please address matters pertaining to ads, membeship, or use of Editor: Connie Rajnak [email protected] the ACA mailing list to: Editor: Judith L. Flippen-Anderson [email protected] Marcia J. Colquhoun, Director of Administrative Services Copy Editor: Jane Griffin [email protected] American Crystallographic Association Book Reviews: Joe Ferrara [email protected]
    [Show full text]
  • FALL2015.Pdf
    Introducing… In Meso In Situ Serial Crystallography mitegen.com/imisx Easy Crystallizaon in LCP • Simple in situ X-ray Diffracon • Standard Goniometer Compable • Serial Crystallography Enabling • Advanced Dual-Sandwich Design Rethink what your LCP crystallizaon plate is capable of. EZ-Cut LCP LCP Tools Easy Access LCP Crystallizaon Plate Starter Kits, Syringes, Lipids & More Take your crystallizaon in LCP to the next level with MiTeGen’s new LCP line mitegen.com/lcp ACA - Structure Matters www.AmerCrystalAssn.org Table of Contents 2 President’s Column 2-4 News from Canada 4 From the Editor's Desk 5-6 Update on Structural Dynamics Chris Cahill 7 What's on the Cover ACA President 8-11 Poster Prizes in Philadelphia 12 Undergraduate Student Reception in Philadelphia Contributors to this Issue What's on the Cover 13-51 Philadelphia ACA Meeting Page 7 21 Index of Advertisers 53-54 2015 ACA Summer Course 56 What's New on the ACA History Website Spotlight on Stamps Juanma García-Ruiz Net RefleXions 15 Plenary Lecturer in Philadelphia 58-59 Puzzle Corner 59 YSSIG Activities 60-61 48th Erice International School of Crystallography 61-62 Updates from 2014-2015 AIP Science & Technology Fellows 62 CSD50 Symposium Daniel Rabinovich 64-65 News & Awards Spotlight on Stamps 65-66 Book Reviews 66-67 2015 Wisconsin Crystal-Growing Competition 68 Net RefleXions 69 CCDC Data Deposition Service Enhancement 70-71 ACA 2016 Denver Preview 72 Future Meetings Anastasiya Vinokur Net RefleXions Contributions to ACA RefleXions may be sent to either of the Editors: Please address matters pertaining to advertisements, membership Judith L.
    [Show full text]
  • Amino Acid Complexes
    molecules Article Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes David B. Hobart, Jr. 1,2 , Michael A. G. Berg 1 , Hannah M. Rogers 1 and Joseph S. Merola 1,* 1 Department of Chemistry, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA; [email protected] (D.B.H.J.); [email protected] (M.A.G.B.); [email protected] (H.M.R.) 2 Air Liquide Advanced Materials, 197 Meister Ave., Branchburg, NJ 08876, USA * Correspondence: [email protected] Abstract: The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and 1H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. The molecular geometries of the products are discussed. Except for the alanine complex, all complexes incorporate water molecules into the extended lattice and exhibit N-H···O and/or O···(HOH)···O hydrogen bonding interactions. The non-covalent interactions are discussed in terms of the extended lattice structures exhibited by the structures. Citation: Hobart, D.B., Jr.; Berg, Keywords: palladium; chelate; amino acid; hydrogen bonding; non-covalent interaction; X-ray M.A.G.; Rogers, H.M.; Merola, J.S. crystallography Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes. Molecules 2021, 26, 4331. 1. Introduction https://doi.org/10.3390/ Prior work from our group has dealt with the simplest α amino acids, the glycines [1], molecules26144331 and the cyclic amino acids, the prolines [2], respectively.
    [Show full text]
  • The Functions and Importance of CH···O Bonds in SET Domain Methyltransferases
    The Functions and Importance of CH···O Bonds in SET Domain Methyltransferases by Scott A. Horowitz A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Biophysics) in The University of Michigan 2013 Doctoral Committee: Professor Hashim M. Al-Hashimi, Co-Chair Associate Professor Raymond C. Trievel, Co-Chair Professor Charles L. Brooks III Assistant Professor Tomek Cierpicki Professor Anna K. Mapp © Scott Horowitz 2013 Acknowledgements I would like to first and foremost thank Profs. Ray Trievel and Hashim Al- Hashimi. I consider myself lucky to have been able to learn two different approaches to a scientific problem from two tremendous scientists. I would also like to thank my dissertation committee for their many useful suggestions over the years. I would like to thank everyone from the Trievel and Al-Hashimi groups, many of whom have aided and taught me over the years. In particular, Paul Del Rizzo taught me much of what I know about working with proteins and biochemistry, and Jennifer Nimtz was extremely helpful in protein crystallization. Alex Hansen has given me enormous support learning advanced NMR concepts, and most importantly, Joseph Yesselman has been an enthusiastic collaborator on many facets of this work, without whom I would not have been able to complete much of what is presented here. Also, many collaborators from outside the university have been instrumental in this work. Most notably, Lynnette Dirk and Bob Houtz performed the radiometric assays, and gladly took up each new challenge as it came. Also, the advice of Ryan Mehl provided essential advice on making protein with unnatural amino acids and the help of Sam Butcher and Kirk van der Meulen helped us considerably with ITC analysis.
    [Show full text]
  • Experimental and Theoretical Study of the Polynuclear Bismuth Compounds – Dimers, Clusters, Molecular Self-Assemblies and Polyhedral Cage Molecules
    INAUGURAL – DISSERTATION zur Erlangung der Doktorwürde der Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht-Karls-Universität Heidelberg vorgelegt von Kirill Yu. Monakhov (M.Sc.) aus Moskau, Russland Tag der mündlichen Prüfung: 2. Juli 2010 Experimental and Theoretical Study of the Polynuclear Bismuth Compounds – Dimers, Clusters, Molecular Self-Assemblies and Polyhedral Cage Molecules Gutachter: Prof. Dr. Gerald Linti Prof. Dr. Hans-Jörg Himmel Die vorliegende Arbeit wurde in der Zeit von November 2007 bis Mai 2010 am Institut für Anorganische Chemie der Ruprecht-Karls-Universität Heidelberg unter Anleitung von Herrn Prof. Dr. Gerald Linti durchgeführt. Meinen Eltern und Großeltern, meinem Bruder, Mariam und ihrer Mutter Irène gewidmet «Die wahre Wissenschaft und das wahre Studium des Menschen ist der Mensch» Pierre Charron, »Le traité de la sagesse« List of Publications Following topics of this thesis are prepared to be published: 11. Aromaticity of indium and bismuth cluster compounds. G. Linti, K. Yu. Monakhov, M. Bühler, T. Zessin, Graduate College 850 Book 2010, manuscript in preparation. 10. Molecular self-assemblies based on (C5Me5)BiX2 units (X = halogen): synthesis, X-ray crystal structures and quantum chemical study. K. Yu. Monakhov, T. Zessin, G. Linti, manuscript in preparation. 9. Seven-vertex cage cluster Bi4[μ3-Fe(CO)3]3 with π-coordinated aromatic ligands and inverted sandwich behavior in the crystal. K. Yu. Monakhov, T. Zessin, G. Linti, manuscript in preparation. Following topics of this thesis have been published during the doctorate period: 8. Cubane-like bismuth-iron cluster: synthesis, X-ray crystal structure and theoretical 4– characterization of [Bi4Fe8(CO)28] anion. K. Yu. Monakhov, T.
    [Show full text]
  • Crystallography News British Crystallographic Association
    Crystallography News British Crystallographic Association Issue No. 123 December 2012 ISSN 1467-2790 European Meeting 27 ACA Meeting Report p6 Margaret Etter Awards p10 ECM27 Reports p11 Crystallography in the Garden p16 ECM 28 Invitation p22 EXPERIENCE TRUE BRILLIANCE Confidence means a revolutionary high-brilliance X-ray system that meets the needs of the most challenging crystallography projects. Agilent’s new GV1000 X-ray diffractometer represents a major leap forward in the generation of X-rays for demanding structural biology applications. The GV1000 combines novel approaches in all core source components, with innovative gradient vacuum technology affording an extremely compact, quiet and high-brilliance X-ray source. See macromolecular structures in a whole new light with the brilliant new Agilent GV1000 X-ray diffractometer. Learn more at www.agilent.com/lifesciences/GV1000. Scan the QR code with your smartphone for more information about GV1000 © Agilent Technologies, Inc. 2012 The DualSource RAPID II The most f lexible diff ractometer in the world • Small molecule crystal structures • Powder diff raction • Protein crystal structures • Absolute determination of chiral compounds • Diff use scattering • Supermolecular structures • Twinned and disordered crystals www.Rigaku.com/dsr2 Rigaku Corporation and its Global Subsidiaries website: www.Rigaku.com | email: [email protected] Crystallography News December 2012 Contents From the Editor. 2 BCA Council 2012. 3 From the President. 4 BCA Administrative Office, Helen Leese Puzzle Corner. 5 First Floor Hornbeam House American Crystallographic Association Hornbeam Business Park Annual Meeting. 6 Harrogate HG2 8QT Tel: +44 (0)1423 855 990 Fax: +44 (0)1423 855 999 Margaret Etter Student Lecture Awards.
    [Show full text]
  • How the Even-Odd Rule, by Defining Electrons Pairs and Charge
    Open Journal of Physical Chemistry, 2015, 5, 28-38 Published Online May 2015 in SciRes. http://www.scirp.org/journal/ojpc http://dx.doi.org/10.4236/ojpc.2015.52004 How the Even-Odd Rule, by Defining Electrons Pairs and Charge Positions, Can Be Used as a Substitute to the Langmuir-Octet Rule in Understanding Interconnections between Atoms in Ions and Molecules Geoffroy Auvert CEA-Leti, Grenoble Alps University, Grenoble, France Email: [email protected] Received 20 April 2015; accepted 25 May 2015; published 28 May 2015 Copyright © 2015 by author and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract In the course of time, numerous rules were proposed to predict how atoms connect through cova- lent bonds. Based on the classification of elements in the periodic table, the rule of eight was first proposed to draw formulas of organic compounds. The later named octet rule exhibited short- comings when applied to inorganic compounds. Another rule, the rule of two, using covalent bonds between atoms, was proposed as an attempt to unify description of organic and inorganic mole- cules. This rule unfortunately never managed to expand the field of application of the octet rule to inorganic compounds. In order to conciliate organic and inorganic compounds, the recently put forward even-odd and the isoelectronicity rules suggest the creation of one group of compounds with pairs of electrons. These rules compass the rule of two for covalent bonds as well as the octet rule for organic compounds and suggest transforming bonds of multi-bonded compounds in order to unify representations of both groups of compounds.
    [Show full text]
  • The British Society of Gastroenterology
    Gut: first published as 10.1136/gut.13.10.836 on 1 October 1972. Downloaded from Gut, 1972, 13, 836-857 The British Society of Gastroenterology The 33rd annual general meeting of the British Society of Gastroenterology was held at Aviemore, Inverness-shire from 28 to 30 September 1972 under the Presidency of Professor W. I. Card. The programme included a very large number of communications of which the abstracts follow, and symposia on 'A new look at gastritis' and 'Gastrooesophageal reflux and its complications'. The Sir Arthur Hurst Memorial Lecture on 'Gut hormones-milestones and signposts' was given by Morton I. Grossman. A general report and a note on the annual business meeting, which was attended by honorary, senior, and ordinary members, is on page 858. Hepatic Damage from Overdose of Paracetamol size and cholesterol and calcium content of gall- stones on rates of dissolution has been studied in R. P. H. THOMPSON, R. CLARK, R. A. WILLSON, V. vitro and in vivo. BORIRAKCHANYAVAT, B. WIDDOP, R. GOULDING, and Selected human gallstones, removed at surgery, R. WILLIAMS (Liver Unit, King's College Hospital and were analysed chemically and by x-ray diffraction Poisons Unit, Guy's Hospital, London) The in- and then exposed to flowing bile of rhesus monkeys creasing use of paracetamol as an analgesic has been with an intact enterohepatic circulation'. Rapid followed by an increased incidence of overdoses. gallstone dissolution was associated with (1) high We have seen 46 patients during two years; 42 who gallstone cholesterol content; (2) bile undersaturated took more than 13 g developed liver damage, and with cholesterol; (3) high surface area: weight ratio.
    [Show full text]
  • Alternative Substrates for Sustainable and Earth-Abundant Thin Film Photovoltaics
    Alternative Substrates for Sustainable and Earth-abundant Thin Film Photovoltaics Ignacio Becerril Romero Aquesta tesi doctoral està subjecta a la llicència Reconeixement 4.0. Espanya de Creative Commons. Esta tesis doctoral está sujeta a la licencia Reconocimiento 4.0. España de Creative Commons. This doctoral thesis is licensed under the Creative Commons Attribution 4.0. Spain License. Alternative Substrates for Sustainable and Earth-abundant Thin Film Photovoltaics Memòria presentada per optar al grau de doctor per la Universitat de Barcelona Programa de doctorat en Enginyeria i Ciències Aplicades Autor: Ignacio Becerril Romero Directors: Dr. Edgardo Saucedo Silva i Dr. Paul Pistor Tutor: Prof. Dr. Alejandro Pérez-Rodríguez Every human civilization has inevitably collapsed. Ours is not going to be different. However, this time we have the knowledge and capacity to decide how we want it to happen. Let’s make it softly, peacefully and living long and happy lives in harmony with nature. Acknowledgments I could not have done this thesis without the help, support, guidance and wisdom of many, many people. I will try to show my gratitude to all of them but, if I forget anybody, do not take it personally. My brain is really exhausted after the hard work of the last months. I would like to start by thanking Edgardo for giving me the opportunity of doing my PhD studies in IREC under his supervision. Likewise, I would like to thank Paul, my second supervisor, for his knowledge and valuable inputs. I have learned a lot from you both and I hope I can keep learning from you in the future.
    [Show full text]