School of Chemistry

Dr Leigh Fôn Jones

Name
Dr Leigh Fôn Jones
Position
Lecturer of Inorganic Chemistry
Email
leigh.jones@bangor.ac.uk
Phone
+44 (0)1248 38 2391
Location
Chemistry Tower

Overview

Our research focuses on the synthesis of inorganic magnetic materials towards applications in fields such as:

  • Molecular magnetism
  • Magnetic coolant materials
  • Coordination polymers (and MOFs)
  • Supramolecular chemistry

Career Synopsis  

  • Lecturer, Bangor University                                                   Jan. 14- present
  • Lecturer, NUI Galway                                                             Sept.08-Dec. 13
  • Postdoctoral Research Fellow, (University of Edinburgh, UK)              Aug.07-Aug.08
  • Postdoctoral Research Fellow, (University of Leeds, UK)                    Nov 05-July 07
  • ARC Fellowship (Monash University, Australia)                                    Feb.05-Oct.05
  • Royal Society International Fellow (Monash University, Australia)     Feb.04-Feb.05 
  • PhD in Inorganic Chemistry (University of Manchester, UK)               Sept.00-Dec.03
  • MChem. (Hons.) with Industrial Experience (University of Manchester, UK)   Sept.96-July 00

Research

My research is based in the field of molecular magnetism which details the design, synthesis and study of novel polynuclear paramagnetic materials whose properties are inherited from their parent mononuclear building blocks and may be tuned by structural variation at the molecular level. More detailed descriptions of my research interests are documented below:  

Single-Molecule Magnets (SMMs) and Paramagnetic complexes

An important subgroup of this large research field are Single-Molecular Magnets (SMMs), which are discrete polymetallic transition metal complexes (i.e. Fig. 1) and are distinguished by their ability to exhibit magnetic hysteresis of molecular origin. This barrier (Ueff) to magnetization reversal (Ueff = S2D) stems from possession of large ground spin states (S) and significant and negative magnetic anisotropy parameters (D). This discovery spawned a new and exciting area of research in the fields of information storage devices, quantum computing and more recently as potential molecular spintronic devices (i.e. molecular transistors and switches) and as magnetic coolant materials arising from the Magnetic Caloric Effects (MCE).


Figure 1 Crystal structure of a [Co8] cage recently produced by the Jones group

Magnetic Coolant Materials

Magnetic refrigerants are complexes / materials capable of causing a significant decrease in their temperature (mK) as a result of exposure to a large fluctuating magnetic field. Paramagnetic transition metal complexes which posses extremely large ground states (S) and negligible zero-field splitting parameters (D) may as a result exhibit the Magnetic Caloric Effect (MCE) and may be addressed as magnetic coolant materials. When a magnetic coolant complex is placed in an adiabatic bath at low temperatures (< 10 K) and introduced to a large external magnetic field, the large magnetic moment of the complex becomes polarised and results in a large drop in magnetic entropy (Sm). In an adiabatic system the total entropy (magnetic + lattice) must remain constant and therefore when the external magnetic field is removed (adiabatic demagnetisation), the spins again randomise and the magnetic entropy increases, thus resulting in an equal but opposite decrease in the lattice entropy which necessitates a substantial drop in temperature (reaching mK). Recent MCE studies on high-spin paramagnetic complexes show that they compete well with conventionally used low T magnetic refrigerant materials.


Figure 2 Crystal structure of a mixed metal [Gd2Cu9] cluster (part of a chain)

 

1, 2 and 3-D coordination polymers
 
Although the ability of SMMs to exhibit molecular magnetic hysteresis is remarkable, this phenomenon currently only functions at temperatures approaching absolute zero.  An alternative approach would be to utilise magnetic polymers, which have significantly higher operating temperatures, but lack the immediate possibility of miniaturisation to molecular scale. 1, 2 and 3-D coordination polymers (a.k.a: Metal-Organic Frameworks, MOFs) comprise metal centres (nodes) linked into extended arrays through rigid organic linker ligands. Our interest lies in utilising paramagnetic polymetallic complexes (i.e. SMMs) as building blocks in the construction of pre-designed 2 and 3-D extended architectures in order to improve their function as potential magnetic materials.

Figure 3 A 1-D chain of H-bonded alternating Mn(III) (purple) and Na(I) (yellow) mononuclear units

 

Magnetic Cages as Supramolecular Hosts

The design and synthesis of self-assembled molecular flasks and containers capable of encapsulating smaller guest molecules continues to fascinate the scientific community. This is due to their potential applications in both the solution and solid state. Examples of their use in solution include anion sensing, catalytic organic transformations and medical diagnostics. In the solid state, interests lie in their potential as gas storage and separation vessels, and as containers for magnetic nanoparticles towards imaging. Recently the Jones group described the structural and magnetic characterisation of a large family of heptanuclear [M(II/III)7(OH)6(L)6](NO3)2 (M = Ni(II), Zn(II), Co(II/III)) complexes, each member comprising pseudo metallocalix[6]arene double-bowl topologies, derived from partial (pseudo) Calix[n]arene Schiff base ligands such as 2-iminomethyl-6-methoxy-phenol (Fig. 4a). More specifically these complexes possess metallic skeletons describing planar hexagonal discs. Their organic exteriors form double bowl shaped topologies which (due to their crystal packing) result in the formation of molecular cavities in the solid state. These confined spaces are shown to behave as host units in the solid state for guests including small organic molecules and charge balancing counter anions, depending on the exact ligand utilised during construction (i.e. Fig. 4b and c). We are currently extending and extrapolation upon this body of work by producing new host materials with pre-meditated molecular cavities via strategic ligand design towards the accommodation of more pertinent guests.

 


Figure 4 (a) General structure of the Schiff base ligands used to form [M7] (M = Co(II/III), Ni(II), Zn(II)) double-bowl metallocalix[6]arenes as shown in (b) and (c).

Publications

List of Peer Reviewed Publications (since 2010)
Total Publications to date: 58

2014

  • High Nuclearity Ni(II) cages from hydroxamate ligands. C. McDonald, S. Sanz, E. K. Brechin, M. K. Singh, G. Rajaraman, D. Gaynor and L. F. Jones. RSC Advances. 2014, 4(72), 38182-38191.
  • Bulking Up: Hexanuclear Oximato Fe(III) Complexes Surrounded by Sterically Demanding Co-Ligands. E. Houton, S. T. Meally, S. Sanz, E. K. Brechin and L. F. Jones. Inorg. Chim. Acta. 2014, 421, 416-422.   

2013

  • Progressive Decoration of a Pentanuclear Cu(II) 12-Metallocrown-4 Towards Targeted 1- and 2-D Extended Networks. C. McDonald, S. M. Taylor, E. K. Brechin, D. Gaynor and L. F. Jones. CrystEngComm., 2013, 15, 6672-6681.
  • Homo- and Heterometallic Planes, Chains and Cubanes. S. T. Meally, S. M. Taylor, E. K. Brechin, S. Piligkos and L. F. Jones. Dalton Trans., 2013, 42, 10315-10325.
  • Synthetic, structural, spectroscopic and theoretical study of a Mn(III)-Cu(II) dimer containing a Jahn-Teller compressed Mn(III) ion. N. Berg, T. N. Hooper, J. Liu, C. C. Beedle, S. K. Singh, G. Rajaraman, S. Piligkos, S. Hill, E. K. Brechin and L. F. Jones. Dalton Trans., 2013, 42, 207-216.

2012

  • Ferromagnetic exchange in a twisted, oxime-bridged [MnIII2] dimer. E. Houton, S. M. Taylor, C. C. Beedle, J. Cano, S. Piligkos, S. Hill, A. G. Ryder, E. K. Brechin and L. F. Jones. Dalton Trans., 2012, 41(27), 8340-8347.   
  • Investigating the Solid State Hosting Abilities of Homo- and Heterovalent [Co7] Metallocalix[6]arenes. S. T. Meally, C. McDonald, P. Kealy, S. M. Taylor, E. K. Brechin and L. F. Jones. Dalton Trans., 2012, 41(18), 5610-5616.  
  • Old Dog, New Tricks: 2,2´-Biphenol as a Bridging and Book-End Ligand in Discrete and Extended Co(II) Architectures. N. Berg, S. M. Taylor, A. Prescimone, E. K. Brechin and L. F. Jones. CrystEngComm., 2012, 14(8), 2732-2738. 
  • What controls the magnetic interaction in bis-m-alkoxo Mn(III) dimers? A combined experimental and theoretical exploration. N. Berg, T. Rajeshkumar, S. M. Taylor, E. K. Brechin, G. Rajaraman and L. F. Jones. Chem. Eur. J., 2012, 18, 5906-5918.

2011

  • Twisted Molecular Magnets. R. Inglis, C. Milios, L. F. Jones, S. Piligkos, E. K. Brechin. Chem. Commun., (Feature Article), 2011, 48, 181-190.
  • Accidentally on purpose: construction of a ferromagnetic, oxime-based [MnIII2] dimer. R. Inglis, E. Houton, J. Liu,A. Prescimone,J. Cano,S. Piligkos,S. Hill, L. F. Jones and E. K. Brechin. Dalton Trans., 2011, 40, 9999-10006.
  • A Series of Alternating Na+ / M3+ (M = Mn, Fe) Covalent and Ionic Chains.N. Berg and L. F. Jones. CrystEngComm., 2011, 13(17), 5510–5518.

2010

  • Two Heptacopper(II) Disk Complexes with a [Cu7(μ3-OH)4(μ-OR)2]8+ Core. J. Henkelis, L. F. Jones, M. deMiranda, C. Kilner, M. A. Halcrow. Inorg. Chem., 2010, 49, 11127-11132.
  • Alternating Na/Mn Covalent and Ionic Chains. N. Berg, L. F. Jones. CrystEngComm., 2010, 12(11), 3518-3521.
  • Towards Control Over Magnetism in Metal-Organic Capsules. J. L. Atwood, E. K. Brechin, S. J. Dalgarno, R. Inglis, L. F. Jones, A. Mossine, M. J. Paterson, N. P. Power, S. J. Teat. Chem. Commun., 2010, 46, 3482-3486.
  • A Family of Double-Bowl Pseudo Metallocalix[6]arene Discs. S. T. Meally,C. McDonald,G. Karotsis,G. S. Papaefstathiou,E. K. Brechin, P. W. Dunne,P. McArdle,N. P. Power,L. F. Jones. Dalton Trans., (Special Issue on Molecular Magnetism), 2010, 39, 4809 – 4816.
  • Planar [Ni7] Discs as Double-Bowl, Pseudo Metallocalix[6]arene Host Cavities. S. T. Meally, G. Karotsis, E. K. Brechin, G. S. Papaefstathiou, P. W. Dunne, P. McArdle, L. F. Jones. CrystEngComm., 2010, 12, 59-63.   

 

Research Group

The Jones group has particular expertise in the exploration of various synthetic methodologies towards producing novel magnetic materials. If you are interested in working within the Jones group, please do not hesitate to contact me at the email address provided.

Current PhD students:

  • Mari Slater-Parry (2014-present; Dual Senior Demonstrator role)
  • Edel Houton (2010-present; Funded by the IRCSET Embark Program at NUI Galway, Ireland)
  • Cecelia McDonald (2010-present; Funded by a College of Science Fellowship at NUI Galway, Ireland)

Previous PhD students:

  • Dr. Nelly Berg (2009-12): Current profession: Research and Development position at Intel® (Leixlip, Co. Kildare, Ireland).
  • Dr Sean T. Meally (2009-12; BOC Postgraduate Award winner for best PhD thesis). Current profession: Teacher.

 

Collaborations

We have a broad range of collaborators as listed below.

  • Prof. Euan K. Brechin (University of Edinburgh)
  • Prof. Stephen Hill (Florida State University)
  • Prof. David Collison (University of Manchester)
  • Dr. Marco Evangelisti (CSIC-University of Zaragoza)
  • Dr. Stergios Piligkos (University of Copenhagen)
  • Dr Gopalan Rajaraman (Indian Institute of Technology, Mumbai)
  • Dr Declan Gaynor (RCSI-Bahrain)
  • Dr. Nicholas Power (London South Bank University)
  • Prof. Giannis S. Papaefstathiou (University of Athens)
  • Dr. Alan G. Ryder (NUI Galway)
  • Dr Patrick O`Leary (NUI Galway)
  • Dr Constantinos Milios (University of Crete)    

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