Project

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Chemical bonding in molecular crystals at high pressure

Applicant Macchi Piero
Number 126788
Funding scheme Project funding (Div. I-III)
Research institution Departement für Chemie und Biochemie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Physical Chemistry
Start/End 01.10.2009 - 30.09.2012
Approved amount 202'082.00
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Keywords (5)

X-ray diffraction; high pressure; hydrogen bonding; chemical bonding; crystallography

Lay Summary (English)

Lead
Lay summary
For many years, the goal of chemists has been finding relations between the molecular structure and the molecular properties. This includes understanding the nature of chemical bonds, predicting the molecular reactivity and the response toward external stimulus or otherwise the spontaneous behaviors of materials. Many empirical or semi-empirical relations have been proposed, leading sometimes to interesting and widely adopted interpretative frameworks (for example, the structure correlation analysis, by Dunitz and Bürgi). While the molecular structures can be nowadays determined with very high accuracy, many intriguing connections between structure and properties are not yet solved. The interest of scientists has now moved toward the understanding and rationalization of supramolecular structures. For this reason chemical bonding and material properties that depend on soft interactions are currently much exploited. This project intends to investigate how molecular and supramolecular changes induced by external stress modify the chemical bonding and the aggregation of molecules in the solid state. Combination of experimental X-ray diffraction and theoretical calculations with periodic boundary conditions will be adopted to investigate structural changes in molecular crystals, at high pressure. This will provide more information on the potential energy associated with the intermolecular interactions. In this study, various kinds of hydrogen bridged aggregates will be investigated, with the aim to challenge the current theories on the strong hydrogen bond. This project will also investigate the possibility to obtain higher resolution structural determinations. This will enable observing structural changes occurring in the molecular skeleton. For example, in metal organic complexes the metal-ligand linkage and the bonding within the organic ligands will be accurately investigated. One goal is understanding the relative role of the different resonant structures of a molecule and see how the bonding mechanism change as a function of the external compression.Some recent observations demonstrate the possibility to obtain at high pressure a segregation of ionic moieties in the solid state structures of elemental (covalent) solids or hydrogen bonded molecules. These findings are very interesting because they allow to investigate an entirely new chemistry. In facts, the energy supplied to the system through pressure is such that when the system contains different electronic configurations, their relative contributions can be significantly modified. The possibility to map the electron density from diffraction at high pressure will be also investigated.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
High pressure modification of organic NLO materials: large conformational re-arrangement of 4-aminobenzophenone
Marelli Elena, Casati Nicola, Gozzo Fabia, Macchi Piero, Simoncic Petra, Sironi Angelo (2011), High pressure modification of organic NLO materials: large conformational re-arrangement of 4-aminobenzophenone, in CrysEngComm, 6845-6849.
On the nature of chemical bonding in γ-boron
Macchi Piero (2011), On the nature of chemical bonding in γ-boron, in Journal of Superhard materials, 33, 380-387.
Reversible Pressure-Induced Amorphization of a Zeolitic Imidazolate Framework
Bennet Thomas D., Simoncic Petra, Moggachm Stephen A., Gozzo Fabia, Macchi Piero, Keen David A., Tan Jin-Chong, Cheetham Anthony K. (2011), Reversible Pressure-Induced Amorphization of a Zeolitic Imidazolate Framework, in Chemical Communications, 7983-7985.
Thermal, Spectroscopic, and Ab Initio Structural Characterization of Carprofen Polymorphs
Bruni Giovanni, Gozzo Fabia, Capsoni Doretta, Bini Marcella, Macchi Piero, Simoncic Petra, Berbenni Vittorio, Milanese Chiara, Girella Alessandro, Ferrari Stefania, Marini Amedeo (2011), Thermal, Spectroscopic, and Ab Initio Structural Characterization of Carprofen Polymorphs, in Journal of Pharmaceutical Sciences, 100(6), 2321-2332.
Ab Initio Quantum Chemistry and Semi-Empirical Description of Solid State Phases Under High Pressure: Chemical Applications
Macchi Piero (2010), Ab Initio Quantum Chemistry and Semi-Empirical Description of Solid State Phases Under High Pressure: Chemical Applications, in E. V. Boldyreva P. Dera (ed.), Springer, DORDRECHT, 325-339.
α and β forms of oxalic acid di-hydrate at high pressure: a theoretical simulation and a neutron diffraction study
Macchi Piero, Casati Nicola, Marshall William G, Sironi Angelo (2010), α and β forms of oxalic acid di-hydrate at high pressure: a theoretical simulation and a neutron diffraction study, in CrysEngComm, 12, 2596-2603.

Collaboration

Group / person Country
Types of collaboration
Antony Cheetham Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Nicola Casati Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Fabia Gozzo Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Angelo Sironi Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
40th Congres of the Italian Crystallographic Association Talk given at a conference THE HIGH PRESSURE STRUCTURE OF Mn2(CO)10 19.09.2011 Siena, Italy Macchi Piero;
General Assembly of the International union of Crysatllography Poster High pressure structure of Mn2(CO)10: an off-axis M-M bond 22.08.2011 Madrid, Spain Evans Shaun; Simoncic Petra; Macchi Piero;
0th PSI Summer School on Condensed matter Talk given at a conference Phase transitions in crystals 13.08.2011 Zugerberg, Switzerland Macchi Piero;
2nd Meeting of the Italian and Spanish Crystallographic Associations (MISCA2) Talk given at a conference Crystallography without diffractometers. Simulation of molecular crystals at high pressure 30.06.2010 Oviedo, Spain Macchi Piero;
7th Congress on Electronic Structure: Principles and Applications (ESPA2010) Talk given at a conference Molecular crystals at high pressures 29.06.2010 Oviedo, Spain Macchi Piero;


Self-organised

Title Date Place
Meeting of the Swiss Crystallographic Society 16.09.2011 Bern, Switzerland

Associated projects

Number Title Start Funding scheme
144534 Chemical bonding and reactions in molecular crystals at high pressure 01.10.2012 Project funding (Div. I-III)

Abstract

For many years, the goal of chemists has been finding relations between the molecular structure and the molecular properties. This includes understanding the nature of chemi-cal bonds, predicting the molecular reactivity and the response toward external stimulus or otherwise the spontaneous behaviors of materials. Many empirical or semi-empirical re-lations have been proposed, leading sometimes to interesting and widely adopted inter-pretative frameworks (for example, the structure correlation analysis, by Dunitz and Bürgi). While the molecular structures can be nowadays determined experimentally or theoretically with very high accuracy, many intriguing connections between structure and properties are not yet solved. The interest of scientists has now moved toward the understanding and rationalization of supramolecular structures. For this reason chemical bonding and material properties that depend on soft interactions are currently much exploited. This project intends to investigate how molecular and supramolecular changes induced by external stress modify the chemical bonding and the aggregation of molecules in the solid state. Combination of experimental X-ray diffraction and theoretical calculations with periodic boundary conditions will be adopted to investigate structural changes in molecular crystals, at high pressure. This will provide more information on the potential energy associated with the intermolecular interactions. In this study, various kinds of hydrogen bridged aggregates will be investigated, with the aim to challenge the current theories on the strong hydrogen bond, at extreme conditions. This project will also investigate the possibility to obtain higher resolution structural de-terminations, by means of new equipment and experimental procedures, especially making use of synchrotron short wave lengths. This will enable observing structural changes occurring in the molecular skeleton. For example, in metal organic complexes the metal-ligand linkage and the bonding within the organic ligands will be accurately investigated. One goal is understanding the relative role of the different resonant structures of a molecule and see how the bonding mechanism change as a function of the external compression.Some recent observation demonstrate for example the possibility to obtain at high pressure a segregation of ionic moieties in the solid state structures of elemental (covalent) solids or hydrogen bonded molecules. This findings are very interesting because they allow to investigate an entirely new chemistry. In facts, the energy which is supplied to the system through the high pressure is such that when the system contains mixing of different elec-tronic configuration, their relative contribution can be significantly modified. As ultimate goal, the possibility to map the electron density distribution from X-ray diffrac-tion at high pressure will be investigated during this project.
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