Emerging Investigator: Hongwei Yu from Tianjin University of Technology, China

Emerging Investigator: Hongwei Yu

Position             Professor

Postdoc             2016–2017   Northwestern University (USA)

        2014–2016   University of Houston (USA)

Education          2009–2014   Xinjiang Technical Institute of                                                                       Physics &Chemistry, CAS        Ph.D.

                          2005–2009  Jilin University (China)              B.Eng.

ORID                 0000-0002-5607-0628

Read Hongwei Yu’s Emerging Investigator Series article on Inorganic Chemistry Frontiers and learn more about him.

     
  The exploration of new infrared nonlinear optical crystals based on the polymorphism of BaGa4S7  
Zhen Qian, Haonan Liu, Yujie Zhang, Hongping Wu, Zhanggui Hu, Jiyang Wang, Yicheng Wu and Hongwei Yu*

 

Two new polymorphism of BaGa4S7 was successfully discovered and synthesized. Among them, β-BaGa4S7 exhibits the best balance among a large phase-matching SHG response and a wide band gap, as well as the stable physicochemical property.

 

  From the themed collection: Frontiers Emerging Investigator Series  
  The article was first published on 26 Jul 2022  
  Inorg. Chem. Front., 2022, Advance Article  
  https://doi.org/10.1039/D2QI01263D  
     

My research interests

Key words: nonlinear optical crystals, solid state chemistry, crystal growth
Nonlinear optical (NLO) crystals—the unique materials capable of generating coherent radiation at various difficult-to-access wavelengths through frequency conversion technologies—are of particular importance for laser and photonic technologies. Currently, the commercial NLO crystals are mainly used in the ultraviolet (UV) and visible regions. However, in the deep-UV (λ < 200 nm) and mid-IR (3 μm < λ < 20 μm) regions, the available NLO crystals are still limited. Therefore, my research interests are to design, synthesize and grow new NLO crystals for the laser output in deep-UV and IR regions. The materials classes I am interested in include borates, phosphates, chalcogenides and some heteroanionic compounds, etc.

10 Facts about me

I published my first academic article on synthesis, structure and characterization of a new tripotassium cadmium pentaborate in Journal of Solid State Chemistry in 2011.

An accomplishment I’m particularly proud of is that I have synthesized hundreds of new inorganic crystals and determined their structures by single-crystal X-ray diffraction.

My favourite sport is mountain-climbing.  

One of my hidden talents is singing.

One thing I cannot live without is delicious food.

My favorite books were tales of mystery when I was a child.

I always believe that a good chemist would also be a good cooker.

In five years, I hope to get an excellent NLO material for achieving highly effective output of deep-UV lasers.

I chose chemistry as a career because chemistry is magical; it can create a new material world.

The best advice I have ever been given is to cherish everything around you.

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Dynamic lanthanide exchange between quadruple-stranded cages: the effect of ionic radius differences on kinetics and thermodynamics

Advances in the coordination chemistry of multinuclear compounds have been exploited to drive the self-assembly of many new discrete metallo-supramolecular motifs. Due to the nature of the metal-ligand interactions, many of these systems have a dynamic character with reversible association and dissociation able to generate complex mixtures. Unveil such dynamic behaviours, it is a priority to fully understand, control and design their functional properties. Among metallo-supramolecular systems, lanthanide (Ln) based architectures attracts much attention due to their remarkable optical and magnetic properties. However, design and control of the final supramolecule is very challenging due to the inner nature of the 4f orbitals and consequent small ligand-field effects. There is, however, a steady variation of the effective ionic radius (EIR) across the series, the so called “lanthanide contraction”. Although the radii difference (ΔEIR) is quite small (ca. 0.20 Å between La3+ and Lu3+ and ca. 0.02 Å between two consecutive lanthanides), it can have important chemical consequences on the nature and features of supramolecular complexes.

Recently, a group headed by Marzio Rancan of ICMATE-CNR (Italy) and collaborators from the University of Padova (Italy) and Dortmund University (Germany) have demonstrated that ΔEIR strongly affects the kinetics of Ln ions exchange between preassembled quadruple-stranded [Ln2L4]2 cages (Figure 1).

Figure 1. (a) Self-assembly of seven [Ln2L4]2− cages (Ln = La, Nd, Eu, Tb, Er, Tm and Lu). (b) Dynamic Ln3+ ion exchange equilibrium between two pre-assembled cages and (c) exponential trend of the kinetic constants depending on the Ln ΔEIR.

The process has been qualitatively and quantitatively characterized by time-dependent electrospray ionization mass spectrometry (ESI-MS). Mixing a series of two homonuclear [LnA2L4]2− and [LnB2L4]2− with increasing Ln3+ ΔEIR always leads to the formation of a statistical mixture of homo- and heteronuclear helicates due to the Ln exchange. All the studied systems have an equilibrium constant close to K = 4. The Ln3+ ΔEIR, hence, does not affect the thermodynamics of the process that is mainly governed by statistical factors and entropy-driven. On the other hand, they demonstrate that the rate of the dynamic ion exchange is Ln radius-dependent (Figure 1b). The kinetic constants of the forward and backward reactions revealed an exponential trend depending on the Ln3+ ΔEIR of the two homonuclear pre-assembled cages (Figure 1c): from the minimum to the maximum value of ΔEIR, the kinetic constants increase by three orders of magnitude. This fundamental study hints new tools and guidelines to study dynamic processes in metallo-supramolecular ensembles, and for the precise preparation and control of lanthanide-based mixed coordination-driven systems.

Corresponding author:

Marzio Rancan is a Research Fellow at ICMATE-CNR (Italy). He received his PhD in Molecular Sciences at the University of Padova in 2009. He did post-doctoral studies at CNR, University of Padova and spent one year in the Molecular Magnetism Group at The University of Manchester (UK).  His current research is focused on the synthesis and characterization of coordination-driven molecular and supramolecular architectures with functional properties. He is the author of about 60 articles.

WEBSITE: http://wwwdisc.chimica.unipd.it/FMNLab/index.html

ORCID: https://orcid.org/0000-0001-9967-5283

RESEARCHGATE: https://www.researchgate.net/profile/Marzio-Rancan

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Mixed-valence organo-triiron complexes as strongly cytotoxic and highly selective anticancer agents

Cancer is a major health issue worldwide, and the development of innovative and effective drugs is an ultimate demand for research. Iron compounds have aroused a great interest in the search for new metal based chemotherapics, on account of their relatively low toxicity and their redox chemistry, exportable to physiological media.

Some ferrocene derivatives have shown a promising anticancer potential, with a strong activity mostly associated with FeII to FeIII oxidation, leading to alteration of the cellular redox balance and subsequent production of toxic substances (reactive oxygen species, ROS). However, they provide a limited variability of the metal coordination set, and they need to be carefully formulated for in vivo applications due to a generally insufficient water solubility.

Since 2019, a series of cationic [FeIFeI] complexes based on the [Fe2Cp2(CO)2] core and comprising a vinyliminium bridging ligand have emerged as a novel class of potential chemotherapeutic agents. Thanks to the unique features of the bimetallic core, these complexes are easily prepared up to gram scale from a commercial precursor in a few synthetic steps. Remarkably, they are amphiphilic and appreciably water-soluble, and exhibit an antiproliferative activity against cancer cell lines which depends on the ligand substituents. The choice of the latter is virtually limitless, thanks to the generality of the synthetic procedure, and this feature allows to optimise physico-chemical properties for biological purposes. Different mechanisms, mainly ROS production but also protein interaction and weak DNA binding, may contribute to the mode of action of these dinuclear structures.

Recently, the group of Fabio Marchetti and co-workers have reported, for the first time, the conjugation of a ferrocenyl moiety with a diiron framework, as a strategy to obtain robust mixed-valence triiron compounds featured by a potent cytotoxicity and excellent selectivity towards cancer cell lines (i.e., IC50 values in the low micromolar/nanomolar range on the cancer cell lines, and up to 35 times higher values on the nontumoral cells).

Figure 1. General structure of the novel triiron complexes derived from the tethering of a ferrocenyl unit and a di-organoiron core. R=Me, aryl, Bz, allyl; R’=Me, Bz; X=CF3SO3, NO3.

A combination of stability studies, electrochemical experiments, iron cellular uptake and targeted biological studies indicate that the cationic triiron complexes synergistically combine the redox behaviour of the ferrocenyl moiety with the amphiphilicity and the versatility of the diiron vinyliminium structure, and that their powerful activity arises from the ability to disrupt the redox homeostasis of tumour cells, through the overproduction of intracellular ROS and the alteration of the thioredoxin reductase, assessed on a synthetic dodecapeptide as a simplified model of the enzyme.

Corresponding Author:

Fabio Marchetti
University of Pisa

Fabio Marchetti received his Degree in Industrial Chemistry from the University of Bologna in 1999 (summa cum laude), and the PhD in Chemistry from the same University in 2003. In 2006 he obtained a researcher position at the University of Pisa, and since October 2018 he has been Full Professor in the same University. FM has co-authored over 200 scientific publications on international journals, 2 book chapters and 2 international patents. His research interests regard the synthesis, the characterization and the properties of new transition metal compounds, and the metal-mediated activation of small organic molecules.

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Emerging Investigator: Lingling Mao from Southern University of Science and Technology, China

Emerging Investigator: Lingling Mao

Position              Associate Professor

Postdoc             2018–2021  UC Santa Barbara

Education          2014–2018  Northwestern University (USA)      Ph.D.

                          2010–2014  Sun Yat-sen University (China)      B.Sc.

Group website    https://faculty.sustech.edu.cn/maoll/en/

ORID                  0000-0003-3166-8559

Read Lingling Mao’s Emerging Investigator Series article on Inorganic Chemistry Frontiers and learn more about her.

     
  “Breathing” organic cation to stabilize multiple structures in low-dimensional Ge-, Sn-, and Pb-based hybrid iodide perovskites  
Congcong Chen, Emily E. Morgan, Yang Liu, Jian Chen, Ram Seshadri and Lingling Mao*

 

By using S-(2-aminoethyl)isothiouronium (ETU) as the templating cation, five new metal iodide hybrids, (ETU)GeI4, (ETU)4Ge5I18, (ETU)PbI4 and (ETU)3Pb2I10 are reported with varied C–S–C angles in the organic cation.

 

  From the themed collection: Frontiers Emerging Investigator Series  
  The article was first published on 06 Aug 2022  
  Inorg. Chem. Front., 2022, Advance Article  
  https://doi.org/10.1039/D2QI01247B  
     

My research interest

Key words: Inorganic Chemistry; Materials Chemistry; Solid-state Chemistry
Materials chemistry: designing functional hybrid materials for optoelectronic applications

Establishing structure-property relationship in hybrid materials

10 Facts about me

I am most passionate about my work in discovering new materials. Solving a new crystal structure is the highlight of the day.

My passion besides work is enjoying great food with my friends.

I love skiing, but I have been stuck for two years without skiing due to COVID19.  

One of my hidden talents is sketching. I find it very relaxing.

One thing I cannot live without is music. I play music all the time when I’m driving or in the office.

Great papers depend not only on good results, but also on great writing. The writing reflects your thought process and whether you can deliver the essence.

A recent epiphany: work does not define who you are. Work is work.

I advise my students to take charge of their lives, have fun and do good science.

The most important quality of a mentor is to take a back seat when needed, and always be there for your mentees.

I have a cat named Schrödinger. He is an one-year-old blue/white British shorthair.

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Emerging Investigator: Yuanbin Zhang from Zhejiang Normal University, China

Emerging Investigator: Yuanbin Zhang

Position              Professor

Education           2013-2018  Zhejiang University                        Ph.D.

                           2009-2013  Nanjing University of Sci & Tech   B. Eng.

Group website    https://www.x-mol.com/groups/zhang_yuanbin

ORID                  0000-0002-8268-384X            Google Scholar

Read Yuanbin Zhang’s Emerging Investigator Series article on Inorganic Chemistry Frontiers and find more about him.

     
  A new boron cluster anion pillared metal organic framework with ligand inclusion and its selective acetylene capture properties  

 

A novel microporous boron cluster pillared metal–organic framework BSF-10 was synthesized with ligand inclusion for efficient C2H2/CO2 and C2H2/C2H4 adsorption separation.

 

  From the themed collection: Frontiers Emerging Investigator Series  
  The article was first published on 19 Jul 2022  
  Inorg. Chem. Front., 2022, Advance Article  
  https://doi.org/10.1039/D2QI00890D
 
     

My research interest

Key words: metal-organic frameworks, supramolecular organic frameworks, gas separation, porous materials, boron cluster chemistry
My research interests mainly focus on the design of new porous materials for selective gas separation (light hydrocarbon splitting, carbon dioxide capture, etc). The gas separation based on traditional distillation method is highly energy-intensive. My work is to design suitable porous adsorbent to realize energy-efficient adsorptive separation of gas mixtures and investigate the structure-property relationship by experiments and theoretical calculation. Metal-organic frameworks (MOFs) and supramolecular organic frameworks (SOFs) are two main materials that I focus on. For different gas mixtures, I design materials with customized properties to recognize the difference. The ultimate target is to achieve efficient gas separation with both high adsorption capacity and high selectivity. Boron cluster anion hybrid supramolecular metal organic frameworks (BSFs) are a new series of crystalline porous materials developed in my group, which have shown benchmark separation performance for C3H8/C2H6/CH4, C2H2/C2H4 and C2H2/CO2 separation. For gas molecules with high polarity, I introduce electronegative elements (F/O) into MOFs’s pore surface to enhance the host-guest interaction. By this strategy, our group have developed a novel MOF termed as ZNU-2 (ZNU = Zhejiang Normal University) for benchmark C3H4/C3H6 separation.

10 Facts about me

I published my first academic article in European Journal of Inorganic Chemistry in 2015. It is also the first paper of my PhD research group. I spent nearly two years to finish the work but a Germany group reported a similar results before me.

I chose chemistry as a career because I want to be a scientist since very young and my middle school science teacher piqued my interest in chemistry.

An accomplishment I’m particularly proud of is the design of the first boron cluster anion pillared supramolecular metal organic framework, which displays a new application of anionic boron clusters. This work was published in Angewandte Chemie in 2019.

One of my hidden talents is cooking. I will be a good cooker if I am not a researcher.

My favourite sport is badminton. I ever obtained 3rd Prize of badminton competition in high school.

A key experience in my education was my visiting time at UCLA. During that stay, I made the decision of changing my research field from organic chemistry to MOFs that I am still insisting on.

The biggest challenge facing me is to get funding as well as to manage the time.

The most important thing I learned from my students is that everyone has their own strengths and weaknesses. It is my job to help them become the best version of themselves.

My most important role models are the advisors Duttwyler, Spokoyny, and Xing during my PhD and postdoc study. They are all great scientists and I learned a lot of things from them.

Guaranteed to make me happy is making progress every day and having new discovery from my lab.

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Heptadentate chelates for 89Zr-radiolabelling of monoclonal antibodies

Zirconium-89 complexation chemistry is an important area of research in the context of developing radiolabelled proteins for applications in diagnostic positron emission tomography (PET) imaging. For this imaging technology, the metalloradionuclide 89Zr4+ ion needs to be sequestered by a ligand to form a coordination complex that is thermodynamically, kinetically, and metabolically stable in biological systems. In this regard, desferrioxamine B (DFO), a natural bacterial siderophore, is one of the outstanding hexadentate linear chelator for zirconium-89, used in clinical trials with 89ZrDFO-radiolabeled antibodies (mAbs). Nevertheless, preclinical studies have demonstrated that 89ZrDFO-mAbs can suffer from dissociation and metal ion release in vivo resulting in partial bone uptake in mice which could be partially due to the incomplete coordination sphere around the metallic cation. Driven by the goal of increasing the stability of the 89Zr4+ coordination complex toward demetallation in vivo, several groups around the world have explored the synthesis and coordination chemistry of novel multidentate chelates with coordination numbers from 6 to 8 but the development of heptadentate remained unexplored.

Recently, a collaborative work between the group of Prof. Dr Jason P. Holland (University of Zurich, Switzerland) and a team from the Institut Plurisdisciplinaire Hubert Curien (IPHC, CNRS, University of Strasbourg, France) have demonstrated that photoactivatable heptadentate chelates could be a new alternative for the ultra-fast, light-induced production of stable 89Zr-mAbs in vivo (Figure 1). The researchers synthesise new chelates, used density functional theory to predict the thermodynamic stability, and studied the in vitro stability of the radiolabelled complexes to find the most promising candidate for in vivo application.

Figure 1. (A) Overview of the light-induced photoradiosynthesis to produce 89Zr-labelled monoclonal antibodies (mAbs) and structure of the ligands (13). (B) Optimised structures of the three model Zr complexes. (C) Bar chart showing the stability of the 89Zr-radiolabelled complexes (formed from chelates 14) under different challenge conditions.

The researchers also selected the most stable complex (Zr-2) and produced 89Zr-radiolabelled onartuzumab (the monoclonal antibody component of MetMAbTM which binds to the human hepatocyte growth-factor receptor c-MET) using photoradiochemical methods. Finally, the pharmacokinetic profile and c-MET targeting was evaluated in vivo and ex vivo by using PET imaging and biodistribution studies in female athymic nude mice bearing subcutaneous MKN-45 human gastric cancer xenografts (Figure 2).

 

Figure 2. (A) Coronal and axial PET images taken through the centre of the tumours showing the spatial distribution of [89Zr]Zr-2-onartuzumab over time after intravenous administration in mice bearing subcutaneous MKN-45 tumours on the right flank. T = Tumour, H = Heart, L = Liver, K = Kidneys. (B) Bar chart showing ex vivo biodistribution data (%ID g-1) for the uptake of [89Zr]Zr-2-onartuzumab (normal group, white; blocking group, blue) and the 6-coordinate control compound [89Zr]Zr-4-onartuzumab (normal group, red; blocking group, green) in mice bearing MKN-45 tumours.

Overall, the researchers proved that [89Zr]Zr-2-onartuzumab provides specific tumour targeting and high tumour-to-organ contrast on the PET pictures and from the biodisitribution analysis. The results obtained in the study confirm that heptadentate complexes of 89Zr display improved stability in vivo compared with hexadentate analogs and are promising candidates for future 89Zr-radiotracer design.

About the corresponding author

Jason P. Holland is from Yorkshire in the UK and is currently an SNSF Professor for Medicinal Radiochemistry at the University of Zurich. Research activities in the Holland group focus on advancing radiolabelling methods through novel bioconjugation approaches for labelling bioactive molecules with various radionuclides (18F, 64Cu, 67/68Ga, 86/90Y, 99mTc, 111In, 177Lu, 188Re, etc).

E-mail: jason.holland@chem.uzh; Twitter: @HollandLab_

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Best Inorganic Chemistry Frontiers Covers of 2021

We are delighted to announce the Best Inorganic Chemistry Frontiers Covers of 2021!

Read below the scientific papers.

A red-light-chargeable near infrared MgGeO3:Mn2+,Yb3+ persistent phosphor for bioimaging and optical information storage applications

Inorg. Chem. Front., 2021,8, 5149-5157
https://doi.org/10.1039/D1QI01158H

Issue 24 Volume 8 Outside Front Cover

Binuclear metal complexes with a novel hexadentate imidazole derivative for the cleavage of phosphate diesters and biomolecules: distinguishable mechanisms

Inorg. Chem. Front., 2021,8, 2684-2696
https://doi.org/10.1039/D1QI00108F

Issue 11 Volume 8 Inside Front Cover

Designing lanthanide coordination nanoframeworks as X-ray responsive radiosensitizers for efficient cancer therapy

Inorg. Chem. Front., 2021,8, 3433-3439
https://doi.org/10.1039/D1QI00442E

Issue 14 Volume 8 Inside Front Cover

Congratulations to the winners of Best Inorganic Chemistry Frontiers Covers of 2021!

We expressed our sincere appreciation for all the support and contributions from our authors, reviewers, and readers in the past 2021.

Looking forward to receiving your high-quality work in 2022.

Happy Chinese New Year!

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A highly active and E-selective Co catalyst for transfer-semihydrogenation of alkynes

The efficient semihydrogenation of internal alkynes to selectively produce either E– or Z-alkenes is one of the main challenges in homogeneous catalysis. Numerous systems were reported in the past, however, such reactions typically require either the use of gaseous hydrogen at high pressure, noble metal catalysts, or rather high catalyst loading at long reaction times, the latter resulting in alkene isomerisation or overreduction to produce alkanes. Amine boranes such as ammonia borane (H3B·NH3) are known to be well-suited for transfer hydrogenation reactions, providing stoichiometric amounts of H2 either by dehydrogenation (i.e. H2 production), followed by hydrogenation, or by stepwise hydride and proton transfer to an organic substrate. Homogeneous precatalysts based on the Co(II) oxidation state have been reported in the past, however, mechanistic insights into such systems were rather limited to date.

Recently, the groups of Jiao and Beweries at LIKAT Rostock have demonstrated that PNN(H) Co(II) complexes serve as very efficient precatalysts for the selective formation of E-alkenes at very mild conditions, suing MeOH and H3B·NH3 as the hydrogen source. This reaction is suggested to take place exclusively via the Co(II) oxidation state, which was corroborated though a combination of control experiments, EPR spectroscopy, and DFT analysis. Key feature for the high activity of this Co system is the proton responsive PNN(H) ligand, possessing a pyrazole fragment that undergoes deprotonation during catalyst activation. The results presented herein could be relevant for the design of other proton responsive ligands for non-noble metal free transfer hydrogenation reactions.

Corresponding author:

PD Dr. Torsten Beweries (Leibniz Institute for Catalysis, Rostock)

Torsten Beweries is head of the department Coordination Chemistry and Catalysis at the Leibniz Institute for Catalysis in Rostock (Germany). He received his PhD in Chemistry at LIKAT in 2008, working on the coordination chemistry of hafnocenes. He then moved to the University of York (UK) for a postdoctoral stay with Prof. Robin N. Perutz in 2009, working on late transition metal complexes for halogen bonding. He returned to LIKAT in 2010, where he established an independent research group. The research field of PD Dr. Torsten Beweries is organometallic chemistry and homogeneous catalysis with focus on new pincer ligands and complexes, main group polymers, and unusual metalacyclic systems. He is the author of 91 articles indexed by SCI and cited more than 1600 times with an index H = 23.

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Unprecedented Organometallic Rare Earth Complexes Containing a Large, Flexible Salophen Ligand

Organometallic chemistry of the rare earth and actinide elements has been a driving force for the development of novel functional materials and catalysts for decades, giving rise to impressive advances in the fields of single-molecule magnetism, luminescence, and polymer sciences. Excitingly, organometallic approaches have always been on the forefront of fundamental chemistry and allowed breakthroughs in the field, not only with the lighter metals but also some of the heaviest actinide candidates. The inherent reactivity of organometallic compounds owing to the apparent labile and reactive metal-carbon bonds renders the isolation and characterization of such molecules exceptionally challenging, especially when aiming at polymetallic rare earth complexes, and is therefore underdeveloped to this date. Consequently, the exploration of suitable synthetic routes to access bridged organometallic metallocene complexes is of great interest for the rare earth and more general inorganic chemistry community.  

Recently, the group of Selvan Demir at Michigan State University has demonstrated that two rare earth metallocene fragments are able to capture the tetradentate salophen ligand, giving rise to the first series of dinuclear salophen-bridged rare earth metallocene complexes with the metals yttrium, gadolinium and dysprosium, Figure 1. These molecules also constitute the first metallocene salophen complexes for any metal ion. Remarkably, the flexibility of the salophen bridge allows the binding pockets to face outwards upon complexation to the metal ions which is a rare, yet intriguing, coordination mode. Consequently, a substantial separation of the metal centers (7.858 – 7.895 Å) occurs leading to weak electronic or magnetic communication between the rare earths. Since the magnitude of magnetic exchange coupling between paramagnetic metal centers and/or organic radical is crucial for the generation of better-performing multinuclear single-molecule magnets,  the magnetic communication in these salophen complexes was explored. 

Figure 1. (A) Schematic view of the salophen-bridged rare earth metallocene complexes. (B) Structure of the rare earth molecules as obtained through single-crystal X-ray diffraction. (C) Arial view of the calculated highest occupied molecular orbital.

The dynamic magnetic properties of the paramagnetic dysprosium complex revealed characteristics of single-molecule magnet behavior, while the static magnetic susceptibility data collected for the paramagnetic gadolinium complex allowed quantification of the magnetic exchange, Figure 2. The determined coupling is of similar magnitude to other polynuclear rare earth complexes containing diamagnetic bridging ligands. DFT calculations on the diamagnetic yttrium conger revealed negligible orbital overlap between the metal center and the salophen ligand in the highest occupied molecular orbital, Figure 1, which may account for the weak magnetic coupling in the paramagnetic variants.

Notably, the lowest unoccupied molecular orbital might be able to be populated with an unpaired electron. Radicals, innate to unpaired electrons, promote strong exchange coupling when placed between rare earth magnetic moments and are, thus, extremely sought-after in the fields of single-molecule magnetism and spintronics. Excitingly, cyclic voltammetry measurements of the salophen

Figure 2. (A) Electron uptake of the dysprosium molecule via electrochemistry. (B) Single-molecule magnet features of the dysprosium complex.

complexes revealed a quasi-reversible feature attributed to the reduction and oxidation of the salophen bridge on the timescale of the electrochemical experiment, Figure 2. This paves the way for chemical reductions of these molecules to generate coveted metal-radical compounds in the future. Noteworthy, chemical functionalization of the salophen backbone may readily be attained which serves as an additional path to augment magnetic coupling and as such highlights the enormous potential of the salophen ligand in organometallic chemistry.

Selvan Demir is an Assistant Professor of Chemistry at Michigan State University. She earned her Dr. rer. Nat. at the University of Cologne researching on scandium solid state chemistry with Prof. Gerd Meyer and scandium organometallic chemistry with Prof. William J. Evans at the University of California, Irvine. Subsequently, she focused on lanthanide-based single-molecule magnets and porous aromatic frameworks with Prof. Jeffrey R. Long at the University of California, Berkeley, and worked on transuranics with Dr. David K. Shuh at the Lawrence Berkeley National Laboratory. Afterwards, she took up a junior professorship of inorganic chemistry at the University of Göttingen. Since 2019, she researches with her group at Michigan State University, on various areas surrounding the chemistry of the rare earth elements and actinides. The research group focuses mainly on organometallic chemistry, small molecule activation, single-molecule magnetism, and lanthanide/actinide separations. A particular emphasis is also on heavy p-block element and uranium chemistry.

 

 

 

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Enantioselective chiral sorption of 1-phenylethanol by homochiral 1D coordination polymers

Amongst the myriad uses of metal-organic frameworks (MOFs) and coordination polymers, separation of complex mixtures, either gaseous or in solution, is one of the most promising applications due to the regular array of well-defined pores. Integration of specific points of interaction that are complementary to the targeted guest species can provide highly selective materials. In particular, precise control of the 3D space within pores may provide a mechanism for enantioselective discrimination for which the exact spatial arrangement of multiple sites of interaction is paramount.

The vast majority of research in this area is driven by 3D metal-organic frameworks, often those possessing permanent porosity. However, for solution-based applications this need not be a prerequisite and materials comprising lower dimensionality coordination polymers may be just as effective is they contain solvent-filled pores.

Recently the group of David Turner at Monash University has shown that a 1D coordination polymer, with pores formed by alignment of loops within the 1D chain, is capable of sorbing 1-phenylethanol with a good degree of enantioselectivity (Figure 1). A closely related material shows no such selectivity, and a reduced uptake capacity, highlighting the importance of structural match between the host framework and the analyte. Ground samples showed higher uptake than unground crystals for the active material, suggesting an influence of surface area or ease of permeation into the solid. Both static (soaking) and dynamic (“micro-LC”) methods showed enhanced uptake of one enantiomer from a racemic solution of 1-phenylethanol, albeit not perfect separation. The group was also able to crystallographically determine the binding site of the preferred enantiomer (Figure 2), showing an array of hydrogen bonding interactions that lie behind the enhanced uptake of one enantiomer over the other.

These results highlight the potential of non-3D coordination polymers in chemical separations and demonstrate the array of host-guest interactions that are required for separations of very similar compounds.

Figure 1. The chiral material contains guest-filled pores resulting from the alignment of loops within the 1D coordination polymer.

Figure 2. The preferred enantiomer of the guest is found crystallographically within the binding pocket, highlighting the array of interactions that hold it in place and provide the enantioselectivity.

Corresponding Author:

David Turner is a Senior Lecturer in the School of Chemistry at Monash University, Australia. After receiving his PhD in 2004 from King’s College, London, he held a number of fellowships at Monash University prior to joining as a Faculty member. Research in the Turner group revolves around metallosupramolecular assemblies, exploring both coordination polymers/MOFs and coordination cages with a particular emphasis on chirality. Dr Turner has published over 130 papers, in addition to two books, attracting almost 5000 citations and an h-index of 32.

https://research.monash.edu/en/persons/david-turner

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