News

CMM paper on the cover of ChemPhysChem

For a new publication, titled "Structural and photophysical properties of various polypyridyl ligands: A combined experimental and computational study", in the ChemPhysChem Journal (Impact factor 3.144), the CMM made the cover for the journal issue of November 2020. ChemPhysChem is one of the leading chemistry/physics interdisciplinary journals for physical chemistry and chemical physics. The cover shows the interaction between visible light and the building blocks of covalent triazine frameworks, which are promising heterogeneous catalysts. The manuscript shows, via a combined computational and experimental study, that the position of the main absorption peak in the UV-Vis spectra of the building blocks of covalent triazine frameworks can be shifted significantly to lower energies by adding NH2.

CMM in Nature Catalysis on Molecular Palladium in Zeolites

Shape selective C-H activation using Molecular Palladium in Zeolites

An international collaborative study led by the Centre for Membrane separations, Adsorption, Catalysis and Spectroscopy for Sustainable Solutions (cMACS) at KU Leuven, in collaboration with the Center for Molecular Modeling (CMM) at Ghent University, the Smart Materials Research Institute at the Southern Federal University (Russia) and the National Institute of Chemistry (Slovenia) has shown that cationic palladium hosted in zeolites can catalyse C-H functionalization reactions with unprecedented shape-selectivity. The findings introduce a novel concept to the field of catalysis, in which exceptional control of selectivity can be achieved in transition metal (TM) catalysed arene C-H activation through the spatial confinement of TM sites in zeolite pores.

An ongoing challenge in the fine chemical industry is to design and identify catalytic systems that are both highly recyclable and easy to separate from products, and can exhibit high selectivity and activity towards the target transformation. In this context, TM-exchanged zeolites are promising candidates as they offer the possibility to combine the strengths of homogeneous and heterogeneous catalysis to afford a superior class of catalyst for use in industry. A particular reaction of high interest in industry is the catalytic coupling of aromatics to form biaryl motifs, which are extensively found in fine chemicals. Under traditional cross-coupling conditions the aromatic reagents must be pre-functionalized, therefore leading to extra steps and costs in the synthesis. For this reason, in recent years attention has shifted towards the direct C-H C-H coupling of aromatics. Homogeneous catalysts are now very well-developed for this purpose, but the development of analogous single-site heterogeneous catalysts can offer unique advantages. For example, the microscopic pores and channels present in the zeolite catalyst may direct regioselective activation of specific C-H bonds, while site isolation of the active metals can limit the catalyst deactivation caused by the aggregation of metallic nanoparticles.

Researchers at KU Leuven identified that cationic palladium can dock to zeolite H-Beta in a stable fashion, and effectively catalyse the oxidative homocoupling of toluene to produce bitolyl in high turnover numbers. Moreover, of the 6 possible isomers that could be formed in the reaction, p,p’-bitolyl is produced with an unprecedented 80 % selectivity, while the yield of products featuring at least one para-substituted aryl group reaches a staggering 97 %. Interested in both the mechanism of this Pd-Beta catalysed coupling reaction and the origin of this unprecedented shape-selectivity observed for the oxidative homocoupling of toluene, researchers at the CMM employed a combination of static and dynamic Density Functional Theory (DFT) calculations on the Pd-Beta system to investigate the reaction. The proposed catalytic cycle, supported by advanced experimental characterization techniques, shows how the confinement effects of the framework can induce the exceptional selectivity, thus leading the way to further development in the field of zeolite-supported single-site transition metal catalysts. The findings have been published in the journal Nature Catalysis. Read the article here.

CMM with UCL London in Nature Materials

An international study led by the Chemistry Department at University College London (UCL) in collaboration with the Center for Molecular Modeling (CMM) at Ghent University and the Central Laser Facility (CLF) has made a new and unexpected discovery about industrial catalysts that could help to increase the efficiency of the production of chemical building blocks from non-fossil feedstocks such as methanol. Their findings could lead to a reduction of the cost and environmental impact of the process, making it a viable alternative to fossil fuels.

Methanol conversion towards chemicals of higher energy density is a sustainable alternative to fossil fuels. To spur the chemical reactions needed to turn methanol into complex chains of carbon like gasoline industrial catalysts are used. One of the most popular catalysts are zeolites, which are microporous, crystalline structures made up of silicon, aluminium and oxygen atoms that form a framework of cavities and channels, known as pores. Their structure means they are often referred to as molecular sieves. The stability and efficiency of zeolites is a major concern, as the build-up of carbon deposits tend to block the pores, eventually leading to deactivation of the process. At this point, the zeolite must be replaced or reactivated through an expensive, energy-intensive and environmentally unfriendly industrial process that effectively burns away whatever is hindering the catalytic process. These zeolites are of high value to industry and discovering why zeolites deactivate and precisely when the process starts is of great interest to scientists and to industry.

Researchers at UCL, UGent, and CLF were able to provide answers to these questions by applying Kerr gated Raman spectroscopy in combination with molecular simulations. Raman spectroscopy is one of the most common techniques used to investigate catalysis as it can tell which molecules are present during the reaction. However, it suffers from background fluorescence that easily drowns out the Raman signal of interest. That is where the Kerr gate comes into play. In contrast to Raman fluorescence, which is an instantaneous process, the background fluorescence is delayed by a few picoseconds. The Kerr gate can filter out this unwanted fluorescence leaving scientists with a clear Raman signal to read.

Using Kerr gated Raman spectroscopy the team succeeded to resolve the molecular fingerprints at all stages of the catalytic reaction. To interpret the complex Raman spectra, containing contributions from a lot of different hydrocarbons that were produced during the process, molecular simulations were performed by CMM researchers. The combination of experimental observations and theoretical calculations enabled to pinpoint the presence of important hydrocarbon species during the process. In particular, they were able to identify what sort of hydrocarbon was being formed at the moment the catalyst started to deactivate – like catching a criminal holding a knife at a murder scene, they were able to catch the culprit red handed.

In the past, it had been thought that a species of hydrocarbon called polycyclic aromatics (polyaromatics) were the main deactivating agents, but the new research has shown that this is not the case. In fact, shortly before the polyaromatics are formed, another species called polyenes are formed and, in fact, it is they that are present at the moment the catalyst started to deactivate. This was a completely new and unexpected discovery. ‘I think that this will change the way people think about how these materials deactivate because, as soon as you know who the culprits are, you are able to design a strategy,’ said teamleader Andy Beale of UCL.

There is a huge energy cost, as well as time cost, associated with reactivating catalysts frequently, so anything that can keep catalysts doing their job for longer will save money, energy and reduce the environmental impact – resulting in greener fuels. The study could be significant for industry especially as methanol can be produced from biomass stocks – meaning that gasoline may not have to come from fossil fuel stocks in the future.

The project is an ongoing collaboration between University College London, Ghent University, the Central Laser Facility, and the Catalysis Hub – a consortium created with the aim of establishing a world-leading programme of catalytic science in the UK. The findings have been published in the journal Nature Materials.

Read the article here.

Ph.D. position available in the field of Modelling C1 catalysis in nanoporous zeolite materials at operating conditions to convert new feedstocks

The research group of prof. Van Speybroeck, embedded within the multidisciplinary Center for Molecular Modeling at Ghent University, Belgium (CMM,  http://molmod.ugent.be), is looking for a highly motivated researcher to perform state-of-the-art research in the field of theoretical modeling of catalysis in nanoporous zeolite materials. We especially welcome candidates with a strong track record who may become eligible to apply for a prestigious Ph.D. fellowship at our national funding agency (FWO).

More info about the CMM

The CMM groups about 40 researchers of the faculties of Science and Engineering and Architecture with molecular modeling interests and is unique in the university as it clusters researchers with various backgrounds, from various departments and faculties. The CMM aims to model molecules, materials and processes at the nanoscale by bringing together physicists, chemists, (bio-)engineers and stimulating collaborations across disciplines. This multidisciplinary collaborative mission is the DNA of the CMM and key to achieve scientific excellence in the field of molecular modeling.

The CMM focuses on frontier research in six major areas: chemical kinetics in nanoporous materials, computational material research on the nanoscale, spectroscopy, many-particle physics, model development and bio- and organic chemistry. The six areas define the core-business of the main activities, and research in each of them is performed within the frame of a strong network with partners at Ghent University, in Flanders and at an international level. The research of this Ph.D. position is situated in the “Nanoporous Materials” research area, however to pursue excellence  we strongly stimulate interactions between the various researchers in our team as well as with our vast network of national and international partners. The research of the CMM is internationally regarded to be at the forefront in its field.

The prospective candidate will join a strongly connected research team and will collaborate with national and international academic partners. He/she will benefit from the experience present in the research group to model chemical transformations at operating conditions. A strong body of expertise was developed in this area in the framework of various ERC grants.

More info about the research topic

This PhD research will focus on modelling C1 catalysis in nanoporous zeolite materials. C1 catalysis – the conversion of one-carbon molecules such as CO2, CO, CH4, CH3OH into high-value platform chemicals and liquid fuels – has attracted widespread attention in the quest for reducing anthropogenic greenhouse gas emissions.   The conversion of non-fossil feedstocks like biomass as well as to recycle CO2 into high-value chemicals, requires the design of next generation multifunctional catalysts which are highly selective and also robust in a broad operation window. In general, the activation of thermodynamically stable C1 molecules like CO2 and their transformation to olefinic and aromatic products, the main building blocks of the chemical industry, is highly challenging. Thanks to their specific porous nature, zeolite materials will play a prominent role in the conversion of C1 compounds. A thorough understanding of the persistent intermediates and governing reaction mechanisms is essential to improve the catalyst efficiency and selectivity. More specifically, for the conversion of CO2 into hydrocarbons, the precise mechanism for C-C bond formation and the role of the presence of CO, CO2, H2 and H2O in the reaction environment are so far improperly understood. Nevertheless, such fundamental insight is still lacking. To this end, computational modeling can prove a powerful method to aid in the understanding of the process and the design of next-generation multifunctional catalysts. In this Ph.D. research, you will systematically investigate C-C coupling reactions in the presence of CO, H2 and H2O for a variety of process conditions. Various reactions are closely related to the mechanisms found within the Methanol-to-hydrocarbons (MTH) process. Therefore, several aspects of the conversion of CO2 and CH3OH species on different zeolite catalysts will be investigated using a large set of modeling techniques. By applying a combination of molecular dynamics (MD) simulations and density functional theory (DFT) calculations, you will perform a mechanistic study on the role of CO2 in these processes, taking into account the complex molecular environment and actual reaction conditions. The research topic will be conducted in close collaboration with excellent experimental groups to guide the design toward new and promising functional materials.  Several collaborative research papers which illustrate our efforts in this area (CO2-to-hydrocarbons and methanol to hydrocarbons) are cited below.1–4 

(1)        Ramirez, A.; Dutta Chowdhury, A.; Dokania, A.; Cnudde, P.; Caglayan, M.; Yarulina, I.; Abou-Hamad, E.; Gevers, L.; Ould-Chikh, S.; De Wispelaere, K.; Van Speybroeck, V.; Gascon, J. Effect of Zeolite Topology and Reactor Configuration on the Direct Conversion of CO2 to Light Olefins and Aromatics. ACS Catal. 2019, 9 (7), 6320–6334.

(2)        Yarulina, I.; Wispelaere, K. D.; Bailleul, S.; Goetze, J.; Radersma, M.; Abou-Hamad, E.; Vollmer, I.; Goesten, M.; Mezari, B.; Hensen, E. J. M.; Martínez-Espín, J. S.; Morten, M.; Mitchell, S.; Perez-Ramirez, J.; Olsbye, U.; Weckhuysen, B. M.; Speybroeck, V. V.; Kapteijn, F.; Gascon, J. Structure–Performance Descriptors and the Role of Lewis Acidity in the Methanol-to-Propylene Process. Nat. Chem. 2018, 10 (8), 804.

(3)        De Wispelaere, K.; Wondergem, C. S.; Ensing, B.; Hemelsoet, K.; Meijer, E. J.; Weckhuysen, B. M.; Van Speybroeck, V.; Ruiz-Martı́nez, J. Insight into the Effect of Water on the Methanol-to-Olefins Conversion in H-SAPO-34 from Molecular Simulations and in Situ Microspectroscopy. ACS Catal. 2016, 6 (3), 1991–2002.

(4)        Westgård Erichsen, M.; De Wispelaere, K.; Hemelsoet, K.; Moors, S. L. C.; Deconinck, T.; Waroquier, M.; Svelle, S.; Van Speybroeck, V.; Olsbye, U. How Zeolitic Acid Strength and Composition Alter the Reactivity of Alkenes and Aromatics towards Methanol. J. Catal. 2015, 328, 186–196.

Who are we looking for?

We are looking for a highly motivated and creative Ph.D. candidate with:  

  • An excellent master’s degree of an international equivalent in the field of Chemistry, Chemical Engineering, Physics, Physical Chemistry or a related field;
  • A strong interest in molecular modelling;
  • Excellent research and scientific writing skills;
  • Perseverance and an independent, pro-active working style;
  • The willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
  • Experience with quantum chemistry software (Gaussian, VASP, CP2K,…) and coding (Python, C, ...) is an advantage.
  • Excellent collaboration and communication skills (written and verbally) in English

What can we offer you?

The selected candidate will get the ability to strengthen his/her CV within the context of a strongly motivated and multidisciplinary research team and have to ability to contribute to challenging topical research to solve important societal questions. He/she will have the opportunity to attend various international conferences and to include research stays abroad in the most prominent international research teams in this field within the framework of his/her Ph.D. The successful candidate will end up in a University with a strong PhD community that offers a broad range of training possibilities for PhD candidates, both within the research topic and focused on transferrable skills (e.g. time management, presentation skills, leadership, etc.).

How to apply?

It is the intention to fill this position as soon as possible. Students who will obtain their Master degree in June/July are also eligible. For more information on the position or the CMM, candidates can get in touch with Prof. Veronique Van Speybroeck (Veronique.vanspeybroeck@ugent.be).

Interested candidates are requested to prepare the following documents:

  1. The filled out application form (see Application-Form.doc)
  2. A motivation letter
  3. A curriculum vitae
  4. Copies of the relevant diplomas and grade lists

All these documents should be send to cmm.vacancies@ugent.be, according to the guidelines mentioned in the application form.

 

AttachmentSize
PDF icon Vacancy details148.64 KB
File Application Form99.17 KB

Ph.D. position available in the field of catalysis for the conversion of biomass compounds to platform chemicals

The research group of prof. Van Speybroeck, embedded within the multidisciplinary Center for Molecular Modeling at Ghent University, Belgium (CMM,  http://molmod.ugent.be), is looking for a highly motivated researcher to perform state-of-the-art research in the field of theoretical modeling of catalysis in complex reaction environments. We especially welcome candidates with a strong track record who may become eligible to apply for a prestigious Ph.D. fellowship at our national funding agency (FWO).

More info about the CMM

The CMM groups about 40 researchers of the faculties of Science and Engineering and Architecture with molecular modeling interests and is unique in the university as it clusters researchers with various backgrounds, from various departments and faculties. The CMM aims to model molecules, materials and processes at the nanoscale by bringing together physicists, chemists, (bio-)engineers and stimulating collaborations across disciplines. This multidisciplinary collaborative mission is the DNA of the CMM and key to achieve scientific excellence in the field of molecular modeling.

The CMM focuses on frontier research in six major areas: chemical kinetics in nanoporous materials, computational material research on the nanoscale, spectroscopy, many-particle physics, model development and bio- and organic chemistry. The six areas define the core-business of the main activities, and research in each of them is performed within the frame of a strong network with partners at Ghent University, in Flanders and at an international level. The research of this Ph.D. position is situated in the “Nanoporous Materials” research area, however to pursue excellence we strongly stimulate interactions between the various researchers in our team as well as with our vast network of national and international partners. The research of the CMM is internationally regarded to be at the forefront in its field.

The prospective candidate will join a strongly connected research team and will collaborate with national and international academic partners. He/she will benefit from the experience present in the research group to model chemical transformations at operating conditions. A strong body of expertise was developed in this area in the framework of various ERC grants.

More info about the research topic

This is a position within the framework of a joint Excellence Of Science project (EOS, https://www.fwo.be/en/fellowships-funding/research-projects/eos-research-project/) in collaboration with Prof. Bert Sels (KULeuven), Prof. Bert Maes (UA), Prof. Gwilherm Evano (ULB) and Prof. Christophe Detrembleur (ULiège). In this project named the BioFactory (Understanding and prediction of lignin-derived compound conversion in complex reaction environments for the production of fine chemicals and bio-based polymers) we aim to develop new and green synthetic methodologies for the transformation of the 4-lignin-derived monomers, obtained from an established and efficient lignin-first biorefinery process, into bulk/fine chemicals and polymers. Conversion of non-edible biomass to valuable functionalized chemicals and high-energy density fuels plays an important role in the transition to a non-fossil-based economy. Within this project you will work on modelling activation energies, reactivity patterns and screen for catalysts, ligands and directing groups for C-H and C-O activations. Furthermore, you will be at the front line of unravelling polymerization chemistry of recently developed cyclic(imino)carbonates. Because the scope of the BioFactactory is both to produce platform molecules and to use them for the production of industrially relevant compounds starting from lignin-derived monomers, the problems you will tackle vary both in size and in complexity. Modeling is quintessential to unravel mechanistically the new synthetic routes and optimize selectivities. However, the proposed pathways take place in a complex molecular environment such as hot-pressurized water for the conversion of ferulic acid to bio-catechol (Bomon et al., 2019: https://doi.org/10.1002/anie.201913023). Therefore, you will use a rich plethora of modeling techniques which allow to obtain mechanistic insight at operating conditions, thus at the experimental temperatures and pressures and taking into account realistic solvents. Often we start using density functional theory calculations to gain fundamental understandings of the problems at hand. However, as computational power keeps increasing we are now able to model these systems within a more realistic environment e.g. the solvent environment and/or the realistic catalyst, … To this end free energy profiles can be constructed accounting for the operating conditions, using advanced molecular dynamics methods. Such techniques allow following chemical transformations in-situ, thus closely mimicking the experimental conditions. You will focus mainly on reactions in the field of organic chemistry in a homogeneous environment, ranging from reactions catalysed by organo- and transition-metal catalysts to reactions in complex solvent environments such as hot-pressurized water. Within the project the candidate will work in close collaboration with our experimental partners of the BioFactory project with whom we have already produced high impact publications. Our collaborative efforts within the experimental network, recently gave rise to very high impact papers in the broad field of chemistry (Bomon et al., 2019: https://doi.org/10.1002/anie.201913023; Ouhib et al., 2019: 10.1002/anie.201905969]

Who are we looking for?

We are looking for a highly motivated and creative Ph.D. candidate with:  

  • An excellent master’s degree of an international equivalent in the field of Chemistry, Chemical Engineering, Physics, Physical Chemistry or a related field;
  • A strong interest in molecular modelling;
  • Excellent research and scientific writing skills;
  • Perseverance and an independent, pro-active working style;
  • The willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
  • Experience with quantum chemistry software (Gaussian, VASP, CP2K,…) and coding (Python, C, ...) is an advantage.
  • Excellent collaboration and communication skills (written and verbally) in English

What can we offer you?

The selected candidate will get the ability to strengthen his/her CV within the context of a strongly motivated and multidisciplinary research team and have to ability to contribute to challenging topical research to solve important societal questions. He/she will have the opportunity to attend various international conferences and to include research stays abroad in the most prominent international research teams in this field within the framework of his/her Ph.D. The successful candidate will end up in a University with a strong PhD community that offers a broad range of training possibilities for PhD candidates, both within the research topic and focused on transferrable skills (e.g. time management, presentation skills, leadership, etc.).

How to apply?

It is the intention to fill this position as soon as possible. Students who will obtain their Master degree in June/July are also eligible. For more information on the position or the CMM, candidates can get in touch with Prof. Veronique Van Speybroeck (Veronique.vanspeybroeck@ugent.be).

Interested candidates are requested to prepare the following documents:

  1. The filled out application form (see Application-Form.doc)
  2. A motivation letter
  3. A curriculum vitae
  4. Copies of the relevant diplomas and grade lists

All these documents should be send to cmm.vacancies@ugent.be, according to the guidelines mentioned in the application form.

 

AttachmentSize
PDF icon Vacancy details141.95 KB
File Application Form99.17 KB

Quantum Matters/Meet the Modelers

Quantum Matters/Meet the Modelers: een informele avond met de doctoraatsstudenten, postdocs, professoren en alumni van het Centrum voor Moleculaire Modellering (CMM).

Heb je interesse in fundamenteel onderzoek, maar vraag je je soms af wat de concrete toepassingen zijn? Ben je benieuwd naar wat moleculair modelleren precies is, hoe het relevante maatschappelijke problemen kan helpen oplossen of wat het kan betekenen voor de chemische industrie? Wist je dat we materialen ontwerpen die CO2 efficiënt kunnen opslaan, en zelfs drinkwater kunnen halen uit woestijnlucht? Heb je zin in gratis hapjes en drankjes?

Kom dan zeker eens langs op de bovenste verdieping van de iGent-toren op 18 februari! Op dit evenement laten we je een eerste keer proeven van dit vakgebied op een begrijpelijke en interactieve manier. De nadruk ligt op de toepassingen waarvoor moleculair modelleren gebruikt kan worden. Via een ludieke game laten we je kennismaken met enkele aspecten hiervan. Tot slot laten we ook enkele CMM alumni met verschillende jobprofielen en achtergronden aan het woord. Zij komen vertellen over (het leven na) een doctoraat aan ons onderzoekscentrum, en geven jou de kans om je meest prangende vragen te stellen.

Stel je hapjes veilig en registreer nu via deze link! Tot dan!

Lecture of Prof. Ilja Siepmann

On monday, 25th of November 2019, Prof. Ilja Siepmann will present a lecture entitled Predictive modeling of Adsorption in nanoporous materials: high-throughput screening, machine learning and first principles simulations at CMM in Auditorium A.03 Industrieel Beheer.

J. Ilja Siepmann is a Distinguished McKnight University Professor, a Distinguished Teaching Professor, and member of the graduate faculties in chemistry, chemical physics, chemical engineering, and materials science at the University of Minnesota. He is also the director of the DOE-funded Nanoporous Materials Genome Center and an associate editor for the Journal of Chemical and Engineering Data. He received his Ph.D. in Chemistry from the University of Cambridge. Before joining the University of Minnesota in 1994, Dr. Siepmann carried out postdoctoral research at the IBM Zurich Research Laboratory, the Royal/Shell Laboratory in Amsterdam, and the University of Pennsylvania's Laboratory for the Research on the Structure of Matter. His scientific interests are focused on particle-based simulations of complex chemical systems, including the prediction of phase and sorption equilibria and of thermophysical properties, the understanding of retention in chromatography, and the investigation of microheterogeneous fluids and nucleation phenomena. His research efforts have advanced the capabilities of molecular simulations through the development of efficient Monte Carlo algorithms and transferable force fields

CMM Teamdays in Vlissingen

 

 

 

 

 

On November 4th and 5th, the Center of Molecular Modelling (CMM) organized two inspiring team days in ‘Strandhotel Westduin’ in Vlissingen at the Dutch coast.

These ‘sea classes’ as we call this two-day team event, were attended by 32 of our CMM colleagues, including ZAP, PhD. students, postdoctoral and administrative staff.

During our dense and varied programme, we brainstormed on the first day about how to improve collaboration on projects and challenges for the future. We held group discussions about our communication and PR strategy, as well as about ways of financing fundamental research. Some of our CMM-members shared their insights on career development and internationalization which were discussed further within the whole group. In between the sessions, we went outside for a beach walk or some nice beach games. After dinner, we made the dunes unsafe during some exciting dune night games.

On the second day, after a boosting morning run, the topic of computer infrastructure and data storage has been touched upon during panel discussions. The concept of ‘Active Learning’ has been discussed vividly during a session about education in which good practices were shared. Furthermore, some of our PhD students gave a presentation about our Friday Morning Lectures (FML) accompanied with a real-time voting system. During a session about ‘CMM improvements’, our team got the chance to speak out loud about current practices that can be organized in a more efficient, nice and friendly way.

The team event ended with some informal Q&A ‘on the coach’ which gave us the opportunity to get to know some of our group members even a little better.

It has been two inspiring and dynamic days during which a lot of ideas came up which were all noted neatly. The aim is to organize task force meetings in the coming months about the most urgent and feasible ideas to implement.

Phd position available

PhD position available in the field of "thermodynamic modeling of adsorption in flexible nanoporous materials” under the supervision of prof. L. Vanduyfhuys at the Center for Molecular Modeling, Ghent University, Belgium.

The multidisciplinary Center for Molecular Modeling (CMM, http://molmod.ugent.be), is looking for a highly motivated researcher to perform state-of-the-art research in the field of thermodynamic modeling of adsorption in nanoporous materials. We especially welcome highly motivated candidates with a strong track record who may become eligible to apply for a prestigious PhD fellowships at our national funding agency (FWO).

Thermodynamics may be regarded as one of the most widely applied branches of physics, interwoven in many aspects of life on our planet. Although it was originally developed mainly to increase the efficiency of steam engines, its applications have evolved greatly and now include a description of chemical reactions, physical and chemical equilibria. Statistical thermodynamics is a particularly interesting extension of thermodynamics, where one tries to understand the thermodynamics of macroscopic systems from a statistical description of the microscopically accessible states. The application of statistical physics can be used to make the bridge between the output of molecular simulations such as molecular dynamics and Monte Carlo on the one hand, and the thermodynamic observables we can measure macroscopically on the other hand. In this PhD, it is the intention to apply the principles from thermodynamics and statistical physics to investigate the behaviour of a new class of nanoporous materials, i.e. soft porous crystals (SPCs). Some metal organic frameworks (MOFs) are an example of such SPCs. These MOFs are hybrid materials made up from metal ions or metal clusters linked together by organic linkers. It was discovered that some MOFs show “flexible” behavior in the sense that they are capable of transforming between various phases accompanied by substantial changes in the unit cell volume (up to 40%) while retaining their structural integrity. Such transformations can be instigated by various triggers such as mechanical pressure, temperature as well as adsorption of guest molecules.

The goal of this PhD research is to develop mathematical models for the thermodynamic potential of guest-loaded nanoporous materials as function of temperature, pressure and chemical potential in various ensembles (eg. the canonical and the grand canonical ensemble). To obtain the required information for the construction of these models, the candidate will perform various molecular simulations such as molecular dynamics (MD), Monte Carlo (MC) and classical density functional theory (cDFT). Furthermore, it also intended to implement the resulting thermodynamic models in a user-friendly program package to allow for an easy application of the models.

The prospective candidate will join a strongly connected research team and will collaborate with national and international academic partners. He/she will benefit from the experience present in the Center for Molecular Modeling (CMM), specifically on performing advanced molecular simulations and the development of general procedures to model physical transformations in nanoporous materials, as well as its implementation in dedicated software packages. The CMM is an interfaculty research unit at Ghent University headed by Prof. Van Speybroeck, grouping about 40 scientists from the Faculty of Science and the Faculty of Engineering and Architecture. The research team consists of various junior and senior researchers with various backgrounds which enables us to provide a proper intellectual environment for the conducted research. The CMM performs interdisciplinary research at the crossroads between physics, chemistry and materials engineering with the aim to design molecules, materials, and processes at the nanoscale. To this end, the CMM consists of six synergetic research areas: “Nanoporous materials”, “Solid-state physics”, “Bio/organic chemistry”, “Model and software development”, “Spectroscopy”, and “Many-particle physics”. The research of this PhD situates mainly in the areas “Nanoporous materials” and “Model and software development”, but to enable groundbreaking research at the interface of physics, chemistry, and materials science, we strongly stimulate interactions between the various researchers of all areas as well as with the vast network of national and international partners. The CMM is internationally regarded to be at the forefront in its field.  

Who are we looking for?

We are looking for a highly motivated and creative PhD candidate with:

  • A master’s degree of a university or international equivalent in the field of Physics, Engineering Physics, Physical Chemistry or a related field;
  • Perseverance and an independent, pro-active working style;
  • The willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
  • Experience in coding (Python, C, ...) is an advantage. At the very least, the candidate must be willing to learn these skills during the first year of the PhD.
  • Excellent collaboration and communication skills (written and verbally) in English.

What can we offer you?

The selected candidate will have the opportunity to attend various international conferences and to include research stays abroad in the some of the most prominent international research teams in this field within the framework of his/her PhD. He/she will get the ability to strengthen his/her CV within the context of a strongly motivated and multidisciplinary research team.

How to apply?

It is the intention to fill this position as soon as possible. Fill in the application form (in attachment) and send the form together with all required documents to prof. Louis Vanduyfhuys (louis.vanduyfhuys@ugent.be) and to cmm.vacancies@ugent.be, mentioning “Vacancy PhD position in the field of thermodynamic modeling of adsorption in nanoporous materials” in the subject of your e-mail.

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PDF icon Vacancy (PDF)359.38 KB
File Application form104.36 KB

Computer simulations find the disordered needle in the crystalline haystack: Why smaller nanoporous materials are less flexible

 

New insight in the impact of the crystal size on the flexibility of nanostructured materials can aid the development of ideal nanosensors.

"Crystals are like people, it is the defects in them which tend to make them interesting!" The color and corresponding price of diamonds, the performance of semiconductor devices, or even the mechanical stability of metals. In each of these almost perfectly crystalline materials, material defects and other types of spatial disorder play a crucial role in the resulting material properties. Although this has been acknowledged and consciously applied for a long time—the above quote of Sir Colin Humphreys dates back to 1979—for nanomaterials the true impact of spatial disorder on their macroscopic behavior is in many cases still poorly understood.

For instance, flexible metal-organic frameworks (MOFs)—synthetic nanoporous crystals composed of both organic and inorganic building blocks—become less flexible the smaller the crystal. New research from the Center for Molecular Modeling (CMM) at Ghent University, published in Nature Communications, now demonstrates that this phenomenon originates from a newly identified type of spatial disorder in these materials.

Finding the disordered needle in the crystalline haystack

In general, material defects and spatial disorder only impact a very limited region in the otherwise crystalline material. As a result, it is not straightforward to clearly visualize this disorder. This challenge becomes even more formidable if the spatial disorder can also dynamically propagate through the material. Experimentalists then need high resolution techniques to reveal the instantaneous nanostructure of the material. For computational researches, the opposite challenge arises. As they often work with smaller and completely ordered models in their simulations, they need to develop new models that are sufficiently large to also capture spatial disorder.

Because of these challenges to clearly visualize dynamic spatial disorder in nanomaterials, it remained unclear until now which factors influence the flexible behavior of MOFs. Flexible MOFs form a class of materials that exhibit multiple stable states. Each of these phases can exhibit different material properties, just like defects alter the material properties of diamonds, semiconductors, and metals. Depending on a MOF’s phase, the material can adsorb more or fewer gas molecules, change its color, or become a better conductor. Flexible MOFs are attractive nanosensor materials as the phase of the material can be changed by altering the pressure or the temperature, or by forcing the material to adsorb molecules.

Although researchers already succeeded in visualizing the nanostructure of the different phases of a flexible MOF, given that these phases typically show crystalline order, it remained a mystery how flexible MOFs transition between these crystalline phases. Originally, the idea was that the structure of the material remained crystalline also during the phase transition, such that the phase transition occurs cooperatively throughout the material. However, this idea was indirectly contradicted by recent experimental results that demonstrated that smaller MOF crystals are less flexible than bigger ones.

From cooperative crystals to chaotic materials

To answer this apparent contradiction, researchers at the CMM systematically increased the crystal size of different flexible MOFs in their simulations. They observed that for sufficiently large MOF crystals, with a critical size above 10 nm, phase transitions no longer occur cooperatively. Instead, their simulations demonstrated that it becomes energetically more favorable for the material not to remain crystalline during the transition, but rather to show spatial disorder by allowing two phases to coexist simultaneously in the material. This phase coexistence results in local defects at the interfaces between the two phases (see red areas in the figure).

This work not only uncovers the mechanism behind the phase transition, but also explains why these phase transitions are hard to observe experimentally. The simulations indicate that the material defects that accompany the phase transition are very dynamic, which makes them very difficult to characterize experimentally. Therefore, this study also proposed different pathways that could be used to experimentally observe the spatial disorder demonstrated in this work. The study moreover demonstrated that it becomes energetically less favorable for smaller crystals to tolerate material defects. As a result, these smaller MOF crystals are also less flexible, in accordance with the recent experimental observations. These results now allow to consciously look for spatial disorder in flexible MOFs and to exploit this disorder to develop high-performing nanosensors.

More info

These results were published in Nature Communications:

Unraveling the thermodynamic criteria for size-dependent spontaneous phase separation in soft porous crystals
Sven M.J. Rogge, Michel Waroquier, and Veronique Van Speybroeck
Nature Communications, 10: 4842, 2019. DOI: 10.1038/s41467-019-12754-w

Contact

dr. ir. Sven M. J. Rogge, prof. em. dr. Michel Waroquier, prof. dr. ir. Veronique Van Speybroeck
Center for Molecular Modeling
Technologiepark 46, 9052 Zwijnaarde
E sven.rogge@ugent.be
M +32 (0)478 82 34 19

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